The Protein Kinase C Inhibitor MS-553 for the Treatment of Chronic Lymphocytic Leukemia

Introduction: Treatment of chronic lymphocytic leukemia (CLL) has been transformed by small molecule inhibitors targeting the B-cell receptor (BCR) signaling cascade. The first-in-class small molecule inhibitor of Bruton's Tyrosine Kinase (BTK), ibrutinib, is FDA approved as a frontline therapy for CLL. However, resistance to BTK inhibition has emerged in patients through acquisition of mutations in BTK or its immediate downstream target, PLCG2, emphasizing the need for alternative targets and therapies. BCR signaling remains intact in the presence of these mutations, making targeted inhibition of proteins downstream of BTK an attractive therapeutic strategy. Protein kinase C-β (PKCβ) is a downstream member of the BCR signaling pathway that we have previously demonstrated as an effective therapeutic target in CLL. MS-553 is a potent, ATP-competitive, reversible inhibitor of several PKC isoforms including PKCβ. Therefore, we evaluated the effects of MS-553 in primary CLL cells. Methods: Primary CLL cells were isolated by negative selection and treated with increasing concentrations of MS-553 to a maximum dose of 10 µM. BCR signaling changes were interrogated by change in target protein phosphorylation by immunoblot following a 24 hour drug incubation with and without phorbol ester stimulation (90 minutes) in CLL samples. Inhibition of CpG-mediated activation of CLL cells was measured using flow cytometry (CD86 and HLA-DR) in ibrutinib refractory patient samples at baseline and post-relapse due to the emergence of the p.C481S BTK mutation. CCL3 and CCL4 expression was measured by ELISA after 24 hours in primary CLL cells in the presence or absence of anti-IgM ligation. TNFα expression was also measured by ELISA in negatively selected, healthy donor T cells treated with MS-553 for 24 hours with or without anti-CD3 and anti-CD28 stimulation. Results: At 24 hours, 5 µM MS-553 inhibited downstream BCR signaling in primary CLL cells, demonstrated by 31% reduced phosphorylation of PKCβ (p=0.08, n=5) and several of its downstream targets including GSK3β (40%, p<.01, n=5) , ERK (46%, p=0.02, n=4) , and IκBα (56%, p=0.04, n=5) compared to vehicle treated, stimulated samples. CpG-mediated TLR9 stimulation increases expression of CD86 and HLA-DR in primary CLL cells. In baseline samples from ibrutinib treated patients, 10 µM MS-553 decreased expression of CD86 by 34% and HLA-DR by 91%. In matched patient samples post-relapse due to ibrutinib resistance, MS-553 (10 µM) maintained the ability to decrease expression of CD86 (49%) and HLA-DR (84%). Pro-inflammatory cytokine expression by primary CLL cells stimulated with anti-IgM decreased in the presence of 5 µM MS-553, with CCL3 decreasing by 36% (p=0.06, n=5) and CCL4 decreasing by 79% (p<.01, n=4) compared to vehicle treated, stimulated controls. TNFα expression by healthy T cells increased with anti-CD3 and anti-CD28 stimulation; 1 µM MS-553 reduced TNFα expression by 97% compared to vehicle treated, stimulated controls (p<.01, n=9). Conclusions: MS-553 is a novel and potent inhibitor of PKC demonstrating in vitro efficacy in CLL. MS-553 is able to inhibit BCR signaling by blocking phosphorylation of PKCβ and its downstream targets. CpG-mediated activation is reduced with MS-553 treatment in ibrutinib refractory patient samples both at baseline and post-relapse. Inflammatory signaling by primary CLL cells is further abrogated by MS-553 in its ability to decrease CCL3 and CCL4 cytokine expression. In an ongoing phase I clinical trial of MS-553, patient samples show a potent and dose dependent decrease in PKCβ activity as measured by a clinical biomarker assay. Together, our results suggest that MS-553 targets PKCβ in primary CLL to inhibit signaling and survival, establishing MS-553 as a potential therapeutic for treating CLL. These data justify continued preclinical and clinical work in the development of MS-553 for the treatment of CLL. Disclosures Niesman: MingSight Pharmaceuticals, Inc.: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Zhang:MingSight Pharmaceuticals, Inc.: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Byrd:BeiGene: Research Funding; Ohio State University: Patents & Royalties: OSU-2S; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Ohio State University: Patents & Royalties: OSU-2S; Ohio State University: Patents & Royalties: OSU-2S; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Acerta: Research Funding; Novartis: Other: Travel Expenses, Speakers Bureau; Genentech: Research Funding; Acerta: Research Funding; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Novartis: Other: Travel Expenses, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Genentech: Research Funding; Genentech: Research Funding; Acerta: Research Funding; Novartis: Other: Travel Expenses, Speakers Bureau; BeiGene: Research Funding; BeiGene: Research Funding. Woyach:Verastem: Research Funding; Loxo: Research Funding; Morphosys: Research Funding; Janssen: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; AbbVie: Research Funding; Karyopharm: Research Funding.

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LC-Facseq: A Novel Method for Detecting Rare Resistant Clones in Leukemia

Blood ◽

10.1182/blood-2019-126070 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 3377-3377

Author(s):

Eileen Hu ◽

Hatice Gulcin Ozer ◽

Arletta Lozanski ◽

Tzyy-Jye Doong ◽

Chi-Ling Chiang ◽

...

Keyword(s):

Tumor Cells ◽

Cell Sorting ◽

Research Funding ◽

Clonal Evolution ◽

Ohio State University ◽

Lymphocytic Leukemia ◽

State University ◽

University Patents ◽

Novel Method

Introduction: Targeted irreversible Bruton's Tyrosine Kinase (BTK) inhibitors ibrutinib and acalabrutinib, have revolutionized treatment for chronic lymphocytic leukemia (CLL). While BTK inhibition (BTKi) achieves durable responses in 90% of patients, only 10% achieve minimal residual disease (MRD) negative status. MRD positive patients have persistent residual CD5+CD19+ tumor B cells at approximately 1-5 /mm3 in peripheral blood. These cells may represent a subpopulation of B-cell lymphocytosis pre-malignant cells or may carry a BTK C481, PLCG2, or other CLL mutation that is ultimately responsible for disease relapse. Alternatively, MRD could be derived from the original clones present at initial disease presentation that are not dependent on BTK signaling. Readily available clinical DNA sequencing and MRD monitoring techniques lack the ability to characterize these cells adequately due to their rarity in peripheral blood. To address this problem, we developed a novel method for limited-cells using fluorescence activated cell sorting in tandem with next generation sequencing (LC-FACSeq) to characterize rare tumor subpopulations in the blood and bone marrow. LC-FACSeq may be useful not only for CLL but also other leukemias. Methods: LC-FACSeq uses fluorescent activated cell sorting (FACS) to isolate pure populations of rare tumor cells after which targeted deep sequencing is performed to monitor CLL-related mutations in NOTCH1, SF3B1, and TP53, as well as genes associated with BTKi relapse and resistance: BTK and PLCG2. For validation of this method, we generated libraries from DNA isolated from FACS isolated bulk (n >15000) versus n= 50, 100, 300, or 500 CD5+/CD19+ cells from CLL patients (n=5). Results: All samples analyzed had an average read depth of 1212 (SEM=56) per gene and an average coverage uniformity of 88.24% (SEM=.01). We show that showed that 300-cell LC-FACSeq libraries demonstrated comparable variant calling and minimal noise to standard libraries generated from purified DNA from bulk cells. Using samples from patients with previously identified BTK C481S mutations, we found that both sensitivity and specificity of LC-FACSeq for BTK C481S was 100%. Furthermore, LC-FACSeq reliably amplified BTK C481S signals from subclones as small as 6 in 300 total cells (2%) when mutated tumor cells were serially diluted into BTK wild type tumor cells. In using LC-FACSeq to retrospectively analyze four independent patients who developed Ibrutinib resistance, we found that we could see the emergence of small BTKi resistant subclones as early as 10 months before clinical detection. We next extended LC-FACSeq to examine the clonal architecture of long-term (> 12 months) ibrutinib-treated MRD positive patients. Median treatment time was 5 years. BTK C481S mutations were observed in the latest available on-treatment samples of only one patient. Using LC-FACSeq we observed canonical CLL-associated clonal mutations similar to those observed in previous studies. Of the 14 MRD positive patients, 7 showed subclonal changes in TP53, NOTCH1, POT1, SF3B1, and MYD88 over the course of ibrutinib treatment although we found no correlation or consensus in these clonal shifts. Conclusion: LC-FACSeq is a highly sensitive method of characterizing clonal evolution in rare cells. Our data shows that LC-FACSeq is useful for monitoring sequential acquisition of mutations conferring therapy resistance and clonal evolution in long-term ibrutinib treated chronic lymphocytic leukemia (CLL) patients. We also observe that in most cases, MRD clones after long-term ibrutinib treatment are genetically similar to disease clones from pretreatment baseline. Compared to current MRD monitoring strategies, the main advantages of LC-FACSeq are that 1) variants can be confidently called from rare sorted tumor populations and subpopulations, 2) library generation can be completed in less than a day in a diagnostic laboratory compared to the labor-intensive protocols of traditional NGS approaches, and 3) amplicon panels can be easily customized for application to other types of leukemia and lymphoma. (EH is supported by the Graduate Pelotonia Fellowship and the NIH F30) Disclosures Bhat: Janssen: Consultancy; Pharmacyclics: Consultancy. Rogers:Janssen: Research Funding; AbbVie: Research Funding; Genentech: Research Funding; Acerta Pharma: Consultancy. Woyach:AbbVie: Research Funding; Janssen: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; Karyopharm: Research Funding; Loxo: Research Funding; Morphosys: Research Funding; Verastem: Research Funding. Lozanski:Beckman Coulter: Research Funding; Stemline Therapeutics Inc.: Research Funding; Genentec: Research Funding; Boehringer Ingelheim: Research Funding. Muthusamy:Ohio State University: Patents & Royalties: OSU-2S. Byrd:Novartis: Other: Travel Expenses, Speakers Bureau; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; BeiGene: Research Funding; Ohio State University: Patents & Royalties: OSU-2S; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Ohio State University: Patents & Royalties: OSU-2S; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Novartis: Other: Travel Expenses, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Acerta: Research Funding; BeiGene: Research Funding; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Genentech: Research Funding; Genentech: Research Funding; Acerta: Research Funding.

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A Multicenter Study of Ibrutinib Resistance Development and Intervention with Venetoclax in Patients with Chronic Lymphocytic Leukemia

Blood ◽

10.1182/blood-2019-125360 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 3049-3049

Author(s):

Kerry A Rogers ◽

Lai Wei ◽

Seema A. Bhat ◽

Dan Jones ◽

Erlene K. Seymour ◽

...

Keyword(s):

Bone Marrow ◽

High Risk ◽

Research Funding ◽

Response Assessment ◽

Ohio State University ◽

Lymphocytic Leukemia ◽

State University ◽

Phase 2 ◽

University Patents ◽

Secondary Endpoints

Background: Ibrutinib (ibr) for the treatment of chronic lymphocytic leukemia (CLL) has improved progression-free survival (PFS) compared to other treatments, especially in high-risk patients (pts). However, resistance occurs and is associated with mutations in the drug binding target (BTK) and its immediate downstream target (PLCg2). These ibr resistance mutations (IRmut) are detectable months prior to developing progressive disease (PD) and predict clinical relapse. Prospectively determining the time from starting ibr to development of IRmut and from IRmut detection to PD will improve our understanding of how to manage these patients. Venetoclax (ven) is highly effective after ibr and decreases IRmut. Adding ven to ibr for ibr resistance is a rational choice as this combination is safe and effective in CLL. Adding an agent rather than stopping ibr avoids disease flare associated with ibr discontinuation. This phase 2 study was designed to follow CLL pts taking ibr and at high risk for resistance (observation cohort) and to test ven in combination with ibr for those who develop PD (intervention cohort). This will determine: the incidence of IRmut and PD in this population, the ORR with ibr/ven, and the ability of this combination to eliminate IRmut. Trial Design and Methods: This multisite study will open at 4 centers initially. Eligible pts are adults with CLL taking ibr for ≥12 months and at high risk for ibr resistance defined as having ≥2 prior treatments and del(17p)(p13.1) on FISH panel and/or a complex karyotype. Pts with known IRmut or who cannot continue ibr for any reason are excluded. Enrolled pts enter the observation cohort and are followed every 3 months with a clinic visit, blood counts, and testing for IRmut. Pts who develop IRmut will also have CT scans at their visits to detect PD. Those with IRmut who develop PD by iwCLL 2018 criteria will enter the intervention cohort. Pts in the intervention cohort will start ven in addition to ibr. Ven will be ramped-up over 5 weeks to a target dose of 400mg. Pts will take combination ibr/ven for 12 cycles of 28 days in length. After 12 cycles they will undergo response assessment and those achieving a complete remission (CR) with no detectable leukemia (uMRD) in both the blood and bone marrow will stop ven and continue ibr alone. Those who do not achieve CR with uMRD will continue ibr/ven until cycle 24 and undergo a second response assessment. If in a CR with uMRD after 24 cycles they continue on ibr alone. If a CR with uMRD is not achieved after 24 cycles patients continue ibr/ven until PD, intolerance, death, or end of study which is 30 months after the last patient enters the intervention cohort (Figure). In the intervention cohort all pts will be tested for IRmut in the blood every 3 months with bone marrow testing at response assessments. The study has co-primary endpoints of ORR to combination ibr/ven after 12 cycles and the rate of IRmut negative status at that time in the intervention cohort. ORR will be tested first using a single-stage phase 2 design with a null hypothesis that the rate is ≤50% versus the alternative hypothesis that it is ≥75%. Only if the combination is effective in ORR will the rate of IRmut negative status be formally tested. Constraining overall Type I and II errors to 0.10 using this sequential testing strategy, 26 evaluable pts are required and 28 will be accrued. Secondary endpoints for the intervention cohort are the PFS and overall survival since starting the combination ibr/ven and the incidence and type of adverse events with ibr/ven. Secondary endpoints in the observation cohort are the incidence of IRmut during ibr treatment and the PFS after developing an IRmut. We estimate that 180 pt-years of follow up for the observation cohort will be needed. The yearly rate of mutation development in this population is approximately 20%, therefore this will identify 36 pts with IRmut. Of those with IRmut, approximately 80% will remain eligible to enter the intervention cohort. Accrual to the observation cohort will stop once 28 pts enter the intervention cohort. Conclusion: This multicenter phase 2 trial examines the development of IRmut and clinical resistance to ibr in a cohort of high-risk CLL pts and will determine the efficacy of adding ven to ibr in those who develop PD. We expect to determine the natural course of molecular and clinical ibr resistance in CLL and if adding ven is an effective treatment strategy. Figure Disclosures Rogers: Acerta: Consultancy; Genentech: Research Funding; Abbvie: Research Funding; Janssen: Research Funding. Bhat:Pharmacyclics: Consultancy; Janssen: Consultancy. Stephens:Karyopharm: Research Funding; Gilead: Research Funding; Acerta: Research Funding. Ye:Janssen: Research Funding; Karyopharm: Research Funding; Portola: Research Funding; MingSight: Research Funding; Sanofi: Research Funding. Byrd:Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Acerta: Research Funding; Genentech: Research Funding; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Ohio State University: Patents & Royalties: OSU-2S; Novartis: Other: Travel Expenses, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Novartis: Other: Travel Expenses, Speakers Bureau; BeiGene: Research Funding; BeiGene: Research Funding; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Genentech: Research Funding; Ohio State University: Patents & Royalties: OSU-2S; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Acerta: Research Funding. Woyach:Janssen: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; AbbVie: Research Funding; Karyopharm: Research Funding; Loxo: Research Funding; Morphosys: Research Funding; Verastem: Research Funding. OffLabel Disclosure: This abstract discussion the use of combination ibrutinib and venetoclax in CLL.

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Role of Mutant p53 in the Progression of Chronic Lymphocytic Leukemia

Blood ◽

10.1182/blood-2019-128574 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 2526-2526

Author(s):

Janani Ravikrishnan ◽

Tzung-Huei Lai ◽

Elizabeth Muhowski ◽

Lindsey Brinton ◽

Katie Williams ◽

...

Keyword(s):

Overall Survival ◽

Research Funding ◽

Ohio State University ◽

Lymphocytic Leukemia ◽

Mutant P53 ◽

State University ◽

Rna Seq ◽

Wild Type ◽

University Patents ◽

Downstream Effectors

Patients with Chronic Lymphocytic Leukemia (CLL) have a variety of chromosomal abnormalities and mutations. At diagnosis, about 10% of CLL patients have deletions of chromosome 17 (Del17p) leading to the loss of one allele of tumor suppressor protein TP53, which increases to over 30% in relapsed/refractory disease. Additionally, 83% of patients with a Del17p acquire a mutation on their second TP53 allele at one of several sites within the DNA binding domain. While the consequence of some of these "hotspot" mutations (R175H, R179H, G245D, G248Q/W, Y220, R213X, R273H and R282H) has been described in solid tumors and AML, very little is known of their role in CLL. Clinically, patients with Del17p/Mutp53 have worse overall survival, increased disease progression and are more likely to relapse on the current targeted therapies such as ibrutinib. Although relapse to these treatments is largely due to acquired mutations in Bruton's Tyrosine Kinase (BTK) or its downstream target PLCg2, we hypothesize that the biology of mutant 53 bearing CLL is a key driver of resistance and progression. Specifically, we aim to determine the molecular signature and downstream effectors that allow mutant p53 to drive the adverse biology associated with this subtype. Conversely, we hypothesize that targeting the mutant p53 pathway will lead to better outcomes and overall survival for patients bearing this adverse prognosis marker. We performed high-throughput Sequencing of DNA from 270 CLL patients with high coverage in the exonic regions of TP53 prior to ibrutinib therapy as well as during progression. At baseline, 40% of patients had mutations found in the DNA binding region with the most frequent occurring in R248Q, R175H and R273H. We then characterized each p53 mutant (n=106) functionally in terms of their ability to ability to activate p21, PUMA, and Bax which serve as cell cycle checkpoint and apoptotic effectors of wild type p53 in response to DNA damage. Most mutants were incompetent in upregulating p21, PUMA or Bax at the transcript level. A few mutants upregulated p21 protein in a p53 independent fashion. We then evaluated the consequence of mutant p53 in CLL. We performed chromatin immunoprecipitation (ChIP-Seq), open chromatin signatures (ATAC-Seq) and expression analysis (RNA-Seq) on CLL samples with R248Q or R175H as well as in wild-type (WT) p53 samples. Integration of ChIP, ATAC and RNA Seq profiles indicated that mutant p53 activated a unique transcriptomic profile not shared by wt p53 bearing CLL. Several genes that facilitated survival or progression were downstream targets of mutant p53. Of these, we identified PRKCB (PKC-beta), BCL2L1 (Bcl-xL), EZH2, MLL and MALAT as a potential key downstream effectors of mutant p53. To determine whether mutations at R248Q and R175H in p53 were causal in the observed increases in PKC-beta, Bcl-xL, EZH2, MLL, and MALAT we used CRISPR/Cas9 editing to introduce mutations at R175H and R248Q in the p53 wildtype CLL cell lines HG-3 and PGA-1. These were accomplished by electroporating sgRNA-Cas9 ribonucleoprotein complexes (RNPs). Western blotting of mutants revealed an increase in the mRNA and protein expression of PKC-beta, and BCL-xL in mutant p53 compared to WT. Levels of EZH2 and MLL were not increased in these cells indicating that PKC-beta and Bcl-xL may be direct transcriptional targets upregulated by mutations at R248Q and R175H in p53. Ongoing efforts will characterize the transcriptional profile of all p53 mutants in our cohort to determine whether they all have a unifying transcriptomic profile that confers a gain of function phenotype to this subtype of CLL. Disclosures Byrd: Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; BeiGene: Research Funding; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Ohio State University: Patents & Royalties: OSU-2S; Novartis: Other: Travel Expenses, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Genentech: Research Funding; BeiGene: Research Funding; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Ohio State University: Patents & Royalties: OSU-2S; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Genentech: Research Funding; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Acerta: Research Funding; Ohio State University: Patents & Royalties: OSU-2S; Novartis: Other: Travel Expenses, Speakers Bureau; Acerta: Research Funding; BeiGene: Research Funding; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Acerta: Research Funding; Genentech: Research Funding; Novartis: Other: Travel Expenses, Speakers Bureau. Woyach:Janssen: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; AbbVie: Research Funding; Karyopharm: Research Funding; Loxo: Research Funding; Morphosys: Research Funding; Verastem: Research Funding.

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Rapid Dose Escalation of Venetoclax in Patients with Relapsed/Refractory Chronic Lymphocytic Leukemia Previously Treated with B-Cell Receptor Inhibitor Therapy

Blood ◽

10.1182/blood-2019-124538 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 3045-3045 ◽

Cited By ~ 1

Author(s):

Kristin Koenig ◽

Emily Dotson ◽

Shane Sheredy ◽

Seema A. Bhat ◽

John C. Byrd ◽

...

Keyword(s):

B Cell ◽

Dose Escalation ◽

Research Funding ◽

Tumor Lysis Syndrome ◽

Cell Receptor ◽

Tumor Burden ◽

Ohio State University ◽

Lymphocytic Leukemia ◽

State University ◽

University Patents

Background B-cell receptor signaling inhibition (BCRi) is an effective treatment (trtmt) for patients (pts) with chronic lymphocytic leukemia (CLL), but resistance develops. Venetoclax selectively inhibits anti-apoptotic protein B-cell lymphoma 2 (BCL-2), and has demonstrated efficacy in relapsed/refractory CLL pts, particularly after BCRi. Venetoclax is started at 20 mg daily and escalated weekly over 5 weeks to the goal dose to avoid acute tumor lysis syndrome. However, we observed that many pts with relapsed/refractory CLL relapsing on BCRi progress more quickly than this schedule allows; they may progress while still taking BCRi or vigorously after its discontinuation. Given the need to promptly attain goal venetoclax dose in this population, we developed a rapid dose escalation scheme for venetoclax and reviewed our experience to understand the feasibility, safety, and efficacy of this approach in a properly equipped university setting. Methods We retrospectively evaluated adult pts with relapsed/refractory CLL presenting to The Ohio State University who were treated with a "rapid dose escalation" of venetoclax. Charts were reviewed for previous and concomitant CLL treatments, tumor burden, prognostic factors, performance status, and co-morbidities. Venetoclax dosing was planned for a shorter time period than the 5 weeks described in the label dosing. The dose was increased as quickly as tolerated following the customary doses (20mg, 50mg, 100mg, 200mg, then 400mg). We reviewed the evaluated safety and efficacy outcomes with this approach. Results We treated 34 pts with rapid venetoclax dose escalation. Median age at venetoclax start was 54 years old and were 73.5% men. Pts had a median of 5 previous CLL trtmts (range 2-18). The most recent trtmt was single-agent BCRi in 18 cases, which overlapped with venetoclax in the majority. Only 6 pts had high tumor burden and the majority had low or medium tumor burden. Cytogenetic abnormalities at venetoclax start included: 17 (50.0%) pts with 17p deletion, 5 (14.7%) with 13q deletion, 6 (17.6%) with 11q deletion, and 3 (8.8%) with trisomy 12. Fifty percent of pts had a complex karyotype, and 76.5% had unmutated IGVH status. 24 (80%, n=30 pts that had testing done) pts had confirmed BTK/PLCу2 mutations. The mean time to goal venetoclax dose was 9.6 days (range 4-31); all but 1 pt reached goal dose. Eighteen (52.9%) pts developed tumor lysis syndrome (TLS) by lab criteria at doses from 20-400 mg, 5 pts developed TLS by clinical criteria, and 1 pt experienced grade 3 severity TLS (per Cairo-Bishop definition). Only 4 pts had an elevated uric acid requiring rasburicase. Seventy-three percent of pts achieved at least a partial remission, and 4 pts each had stable or progressive disease. Three pts died within 30 days: 1 from uncontrolled bleeding and neutropenia, 1 due to neutropenic sepsis with invasive fungal infection and gastric perforation, and 1 due to neutropenic septic shock and respiratory failure. Time to best response was mean 50.7 days (range 2-428). Median time to subsequent trtmt was 279.5 days (range 73-430). 23 pts (67.6%) had not progressed at 1 year, and 26 (76.5%) were surviving at 1 year. Conclusion/summary Rapid dose escalation of venetoclax in this pt population is safe and feasible. Despite a high percentage of patients developing TLS (52.9%), all patients recovered without lasting complications and all but one were able to achieve the goal dose of venetoclax. This dosing scheme achieved disease control with 67.6% remaining progression-free at 1 year and the majority of pts surviving. It is reasonable to implement venetoclax rapid dose escalation in the proper hospital setting with ample ancillary support. This approach may be needed for CLL patients with rapidly progressive disease on BCRi. Disclosures Dotson: Abbvie: Consultancy. Bhat:Pharmacyclics: Consultancy; Janssen: Consultancy. Byrd:Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Genentech: Research Funding; Ohio State University: Patents & Royalties: OSU-2S; Acerta: Research Funding; BeiGene: Research Funding; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Novartis: Other: Travel Expenses, Speakers Bureau; Genentech: Research Funding; Acerta: Research Funding; BeiGene: Research Funding; Ohio State University: Patents & Royalties: OSU-2S; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Novartis: Other: Travel Expenses, Speakers Bureau. Woyach:Janssen: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; AbbVie: Research Funding; Karyopharm: Research Funding; Loxo: Research Funding; Morphosys: Research Funding; Verastem: Research Funding. Awan:Genentech: Consultancy; Sunesis: Consultancy; Gilead: Consultancy; Abbvie: Consultancy, Speakers Bureau; Janssen: Consultancy; Pharmacyclics: Consultancy, Research Funding; AstraZeneca: Consultancy, Speakers Bureau. Rogers:AbbVie: Research Funding; Genentech: Research Funding; Janssen: Research Funding; Acerta Pharma: Consultancy. OffLabel Disclosure: Venetoclax- we will be suggesting a faster increase from starting to maximum/goal dose than the dosing label recommends. This is in order to achieve faster disease control.

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IKZF3 Overexpression Phenocopies Gain-of-Function Mutation in Chronic Lymphocytic Leukemia

Blood ◽

10.1182/blood-2020-137085 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 9-9

Author(s):

Shanye Yin ◽

Gregory Lazarian ◽

Elisa Ten Hacken ◽

Tomasz Sewastianik ◽

Satyen Gohil ◽

...

Keyword(s):

Gene Expression ◽

Chronic Lymphocytic Leukemia ◽

Dna Binding ◽

B Cell ◽

Board Of Directors ◽

Research Funding ◽

Lymphocytic Leukemia ◽

Advisory Committees ◽

Bcr Signaling ◽

Experimental Group

A hotspot mutation within the DNA-binding domain of IKZF3 (IKZF3-L162R) has been identified as a putative driver in chronic lymphocytic leukemia (CLL); however, its functional effects are unknown. We recently confirmed its role as a CLL driver in a B cell-restricted conditional knock-in model. IKZF3 mutation altered mature B cell development and signaling capacity, and induced CLL-like disease in elderly mice (~40% penetrance). Moreover, we found IKZF3-L162R acts as a gain-of-function mutation, altering DNA binding specificity and target selection of IKZF3, and resulting in overexpression of multiple B-cell receptor (BCR) genes. Consistent with the murine data, RNA-sequencing analysis showed that human CLL cells with mut-IKZF3 [n=4] have an enhanced signature of BCR-signaling gene expression compared to WT-IKZF3 [n=6, all IGHV unmutated] (p<0.001), and also exhibited general upregulation of key BCR-signaling regulators. These results confirm the role of IKZF3 as a master regulator of BCR-signaling gene expression, with the mutation contributing to overexpression of these genes. While mutation in IKZF3 has a clear functional impact on a cardinal CLL-associated pathway, such as BCR signaling, we note that this driver occurs only at low frequency in patients (~3%). Because somatic mutation represents but one mechanism by which a driver can alter a cellular pathway, we examined whether aberrant expression of IKZF3 could also yield differences in BCR-signaling gene expression. We have observed expression of the IKZF3 gene to be variably dysregulated amongst CLL patients through re-analysis of transcriptomic data from two independent cohorts of human CLL (DFCI, Landau et al., 2014; ICGC, Ferreira et al., 2014). We thus examined IKZF3 expression and BCR-signaling gene expression, or the 'BCR score' (calculated as the mean expression of 75 BCR signaling-associate genes) in those cohorts (DFCI cohort, n=107; ICGC cohort, n=274). Strikingly, CLL cells with higher IKZF3 expression (defined as greater than median expression) had higher BCR scores than those with lower IKZF3 expression (<median) (p=0.0015 and p<0.0001, respectively). These findings were consistent with the notion that IKZF3 may act as a broad regulator of BCR signaling genes, and that IKZF3 overexpression, like IKZF3 mutation, may provide fitness advantage. In support of this notion, our re-analysis of a gene expression dataset of 107 CLL samples (Herold Leukemia 2011) revealed that higher IKZF3 expression associated with poorer prognosis and worse overall survival (P=0.035). We previously reported that CLL cells with IKZF3 mutation appeared to increase in cancer cell fraction (CCF) with resistance to fludarabine-based chemotherapy (Landau Nature 2015). Instances of increase in mut-IKZF3 CCF upon treatment with the BCR-signaling inhibitor ibrutinib have been reported (Ahn ASH 2019). These studies together suggest an association of IKZF3 mutation with increased cellular survival following either chemotherapy or targeted treatment. To examine whether higher expression of IKZF3 was associated with altered sensitivity to ibrutinib, we performed scRNA-seq analysis (10x Genomics) of two previously treatment-naïve patients undergoing ibrutinib therapy (paired samples, baseline vs. Day 220). We analyzed an average of 11,080 cells per patient (2000 genes/cell). Of note, following ibrutinib treatment, remaining CLL cells expressed higher levels of IKZF3 transcript compared to pretreatment baseline (both p<0.0001), whereas no such change was observed in matched T cells (n ranging between 62 to 652 per experimental group, p>0.05), suggesting that cells with high expression of IKZF3 were selected by ibrutinib treatment. Moreover, we showed that ibrutinib treatment resulted in consistent upregulation of BCR-signaling genes (e.g., CD79B, LYN, GRB2, FOS, RAC1, PRKCB and NFKBIA) (n ranging between 362 to 1374 per experimental group, all p<0.0001), which were likewise activated by mutant IKZF3. Altogether, these data imply that IKZF3 mutation or overexpression may influence upregulation of BCR-signaling genes and enhance cellular fitness even during treatment with BCR-signaling inhibitors. We highlight our observation that IKZF3 mutation appears to be phenocopied by elevated IKZF3 expression, and suggest that alterations in mRNA or protein level that mimic genetic mutations could be widespread in human cancers. Disclosures Kipps: Pharmacyclics/ AbbVie, Breast Cancer Research Foundation, MD Anderson Cancer Center, Oncternal Therapeutics, Inc., Specialized Center of Research (SCOR) - The Leukemia and Lymphoma Society (LLS), California Institute for Regenerative Medicine (CIRM): Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Honoraria, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Genentech/Roche: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; VelosBio: Research Funding; Oncternal Therapeutics, Inc.: Other: Cirmtuzumab was developed by Thomas J. Kipps in the Thomas J. Kipps laboratory and licensed by the University of California to Oncternal Therapeutics, Inc., which provided stock options and research funding to the Thomas J. Kipps laboratory, Research Funding; Ascerta/AstraZeneca, Celgene, Genentech/F. Hoffmann-La Roche, Gilead, Janssen, Loxo Oncology, Octernal Therapeutics, Pharmacyclics/AbbVie, TG Therapeutics, VelosBio, and Verastem: Membership on an entity's Board of Directors or advisory committees. Wu:BionTech: Current equity holder in publicly-traded company; Pharmacyclics: Research Funding.

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Variation in Health-Related Quality of Life by Age Among Patients with Chronic Lymphocytic Leukemia

Blood ◽

10.1182/blood.v118.21.2085.2085 ◽

2011 ◽

Vol 118 (21) ◽

pp. 2085-2085

Author(s):

Chris L. Pashos ◽

Christopher R Flowers ◽

Mark Weiss ◽

Nicole Lamanna ◽

Charles M Farber ◽

...

Keyword(s):

Board Of Directors ◽

Research Funding ◽

Age Groups ◽

Lymphocytic Leukemia ◽

Age Group ◽

Employment Equity ◽

Advisory Committees ◽

Related Quality ◽

Health Related ◽

Equity Ownership

Abstract Abstract 2085 Introduction. Although advanced patient age is commonly used as a factor in selecting therapy for patients with chronic lymphocytic leukemia (CLL), based on presumed associations with functional status, limited data exist regarding the relationships between age and physical, emotional, social, and functional well being. We examined the relationships between age and these domains of health-related quality of life (HRQOL) for CLL patients treated in US community practices. Methods. Baseline data were collected as part of Connect CLL®, a prospective observational registry initiated in March 2010 involving centers in the US. Data on patient demographics and clinical characteristics were provided by clinicians. HRQOL was self-reported by patients in the clinic at enrollment. Patients completed 3 psychometrically validated instruments: the Brief Fatigue Inventory (BFI), EQ-5D, and Functional Assessment of Cancer Therapy-Leukemia (FACT-Leu). Standard analyses were conducted of each instrument given clinical characteristics at that time. Reported mean BFI, EQ-5D and FACT-Leu scores were analyzed by age group (<65, 65–74, >74). Statistical significance of score differences among sub-cohorts was ascertained by ANOVA using SAS 9.1. Results. Baseline HRQOL data were reported by 604 patients, enrolled from 161 centers. Patients were predominantly male (62%) and white (90%) with mean age at 69.9 (standard deviation [SD] 11.2) yrs. HRQOL scores by age group are presented: There were no significant differences between the age groups in fatigue as measured by the BFI, or differences in overall HRQOL as measured by the EQ-5D Visual Analogue Scale (VAS) or the FACT-G. Anxiety/depression and self care are EQ-5D domains that also did not vary by age. Although mobility was most impaired in the oldest age group compared to the two younger groups, usual activities and pain/discomfort were worse in both the younger and older cohorts compared to those 65–74 years of age. FACT-Leu results indicated that the social/family domain scores did not vary by age, but that physical, emotional, and functional domains did vary statistically with the oldest typically doing better than the 65–74 year olds, but not necessarily better than those <65. Conclusions. Initial results from the Connect CLL® Registry indicate that HRQOL does not worsen monotonically with older age. In this cohort, both the youngest and oldest age groups had worse HRQOL in certain domains, presenting an inverted v-shaped relationship. Future analyses should be conducted on: (1) how HRQOL may be affected over time with changes in disease; and, (2) how HRQOL may be influenced by alternative therapies. Results reported here should serve as a useful baseline reference. Disclosures: Pashos: Celgene: Membership on an entity's Board of Directors or advisory committees. Flowers:Genentech/Roche (unpaid): Consultancy; Celgene: Consultancy; Millennium/Takeda: Research Funding; Wyeth: Research Funding; Novartis: Research Funding. Weiss:Celgene: Membership on an entity's Board of Directors or advisory committees. Lamanna:Celgene: Membership on an entity's Board of Directors or advisory committees. Farber:Celgene: Membership on an entity's Board of Directors or advisory committees. Kipps:Igenica: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Research Funding; Abbot Industries: Research Funding; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Genentech: Research Funding; GSK: Research Funding; Gilead Sciences: Consultancy, Research Funding; Amgen: Research Funding. Lerner:Celgene: Membership on an entity's Board of Directors or advisory committees. Kay:Celgene: Membership on an entity's Board of Directors or advisory committees. Sharman:Celgene: Membership on an entity's Board of Directors or advisory committees. Grinblatt:Celgene: Membership on an entity's Board of Directors or advisory committees. Flinn:Celgene: Membership on an entity's Board of Directors or advisory committees. Kozloff:Celgene: Membership on an entity's Board of Directors or advisory committees. Swern:Celgene Corporation: Employment, Equity Ownership. Kahn:Celgene Corporation: Employment, Equity Ownership. Street:Celgene: Employment, Equity Ownership. Sullivan:Celgene: Employment, Equity Ownership. Keating:Celgene: Membership on an entity's Board of Directors or advisory committees.

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Five-Year Experience with Single-Agent Ibrutinib in Patients with Previously Untreated and Relapsed/Refractory Chronic Lymphocytic Leukemia/Small Lymphocytic Leukemia

Blood ◽

10.1182/blood.v128.22.233.233 ◽

2016 ◽

Vol 128 (22) ◽

pp. 233-233 ◽

Cited By ~ 53

Author(s):

Susan M. O'Brien ◽

Richard R. Furman ◽

Steven E. Coutre ◽

Ian W. Flinn ◽

Jan Burger ◽

...

Keyword(s):

Chronic Lymphocytic Leukemia ◽

Board Of Directors ◽

Research Funding ◽

Single Agent ◽

Lymphocytic Leukemia ◽

Advisory Committees ◽

Equity Ownership ◽

Grade 3 ◽

Over Time

Abstract Background: Ibrutinib (ibr), a first-in-class, once-daily Bruton's tyrosine kinase inhibitor, is approved by the US FDA for treatment of patients (pts) with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) including pts with del17p. The phase 1b/2 PCYC-1102 trial showed single-agent efficacy and tolerability in treatment-naïve (TN; O'Brien, Lancet Oncol 2014) and relapsed/refractory (R/R) CLL/SLL (Byrd, N Engl J Med 2013). We report efficacy and safety results of the longest follow-up to date for ibr-treated pts. Methods: Pts received 420 or 840 mg ibr QD until disease progression (PD) or unacceptable toxicity. Overall response rate (ORR) including partial response (PR) with lymphocytosis (PR-L) was assessed using updated iwCLL criteria. Responses were assessed by risk groups: unmutated IGVH, complex karyotype (CK; ≥3 unrelated chromosomal abnormalities by stimulated cytogenetics assessed by a reference lab), and in hierarchical order for del17p, then del11q. In the long-term extension study PCYC-1103, grade ≥3 adverse events (AEs), serious AEs, and AEs requiring dose reduction or discontinuation were collected. Results: Median age of the 132 pts with CLL/SLL (31 TN, 101 R/R) was 68 y (range, 37-84) with 43% ≥70 y. Baseline CK was observed in 41/112 (37%) of pts. Among R/R pts, 34 (34%) had del17p, 35 (35%) del11q, and 79 (78%) unmutated IGVH. R/R pts had a median of 4 prior therapies (range, 1-12). Median time on study was 46 m (range, 0-67) for all-treated pts, 60 m (range, 0-67.4) for TN pts, and 39 m (range, 0-67) for R/R pts. The ORR (per investigator) was 86% (complete response [CR], 14%) for all-treated pts (TN: 84% [CR, 29%], R/R: 86% [CR, 10%]). Median progression-free survival (PFS) was not reached (NR) for TN and 52 m for R/R pts with 60 m estimated PFS rates of 92% and 43%, respectively (Figure 1). In R/R pts, median PFS was 55 m (95% confidence intervals [CI], 31-not estimable [NE]) for pts with del11q, 26 m (95% CI,18-37) for pts with del17p, and NR (95% CI, 40-NE) for pts without del17p, del11q, trisomy 12, or del13q. Median PFS was 33 m (95% CI, 22-NE) and NR for pts with and without CK, and 43 m (95% CI, 32-NE) and 63 m (95% CI, 7-NE) for pts with unmutated and mutated IGVH, respectively(Figure 2). Among R/R pts, median PFS was 63 m (95% CI, 37-NE) for pts with 1-2 prior regimens (n=27, 3 pts with 1 prior therapy) and 59 m (95% CI, 22-NE) and 39 m (95% CI, 26-NE) for pts with 3 and ≥4 prior regimens, respectively. Median duration of response was NR for TN pts and 45 m for R/R pts. Pts estimated to be alive at 60 m were: TN, 92%; all R/R, 57%; R/R del17p, 32%; R/R del 11q, 61%; R/R unmutated IGVH, 55%. Among all treated pts, onset of grade ≥3 treatment-emergent AEs was highest in the first year and decreased during subsequent years. With about 5 years of follow-up, the most frequent grade ≥3 AEs were hypertension (26%), pneumonia (22%), neutropenia (17%), and atrial fibrillation (9%). Study treatment was discontinued due to AEs in 27 pts (20%) and disease progression in 34 pts (26%). Of all treated pts, 38% remain on ibr treatment on study including 65% of TN pts and 30% of R/R pts. Conclusions: Single-agent ibrutinib continues to show durable responses in pts with TN or R/R CLL/SLL including those with del17p, del11q, or unmutated IGVH. With extended treatment, CRs were observed in 29% of TN and 10% of R/R pts, having evolved over time. Ibrutinib provided better PFS outcomes if administered earlier in therapy than in the third-line or beyond. Those without CK experienced more favorable PFS and OS than those with CK. Ibrutinib was well tolerated with the onset of AEs decreasing over time, allowing for extended dosing for 65% of TN and 30% of R/R pts who continue treatment. Disclosures O'Brien: Janssen: Consultancy, Honoraria; Pharmacyclics, LLC, an AbbVie Company: Consultancy, Honoraria, Research Funding. Furman:Pharmacyclics, LLC, an AbbVie Company: Consultancy, Honoraria, Speakers Bureau. Coutre:Janssen: Consultancy, Research Funding; Pharmacyclics, LLC, an AbbVie Company: Consultancy, Research Funding; AbbVie: Research Funding. Flinn:Janssen: Research Funding; Pharmacyclics LLC, an AbbVie Company: Research Funding; Gilead Sciences: Research Funding; ARIAD: Research Funding; RainTree Oncology Services: Equity Ownership. Burger:Pharmacyclics, LLC, an AbbVie Company: Research Funding; Gilead: Research Funding; Portola: Consultancy; Janssen: Consultancy, Other: Travel, Accommodations, Expenses; Roche: Other: Travel, Accommodations, Expenses. Sharman:Gilead: Research Funding; TG Therapeutics: Research Funding; Acerta: Research Funding; Seattle Genetics: Research Funding; Pharmacyclics: Research Funding; Celgene: Research Funding. Wierda:Abbvie: Research Funding; Genentech: Research Funding; Novartis: Research Funding; Acerta: Research Funding; Gilead: Research Funding. Jones:Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics, LLC, an AbbVie Company: Membership on an entity's Board of Directors or advisory committees, Research Funding. Luan:AbbVie: Equity Ownership; Pharmacyclics, LLC, an AbbVie Company: Employment, Other: Travel, Accommodations, Expenses. James:AbbVie: Equity Ownership; Pharmacyclics, LLC, an AbbVie Company: Employment. Chu:Pharmacyclics, LLC, an AbbVie Company: Employment; AbbVie: Equity Ownership.

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Targeting PRMT5 to Circumvent Acquired Ibrutinib Resistance in Mantle Cell Lymphoma

Blood ◽

10.1182/blood-2019-128998 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 4065-4065 ◽

Cited By ~ 1

Author(s):

Shelby Sloan ◽

Fiona Brown ◽

JI Hyun Chung ◽

Alexander Prouty ◽

Esther Wheeler ◽

...

Keyword(s):

Research Funding ◽

Disease Burden ◽

Cell Lymphoma ◽

Ex Vivo ◽

Ohio State University ◽

State University ◽

University Patents ◽

Mantle Cell ◽

Ibrutinib Resistance ◽

Dimethyl Arginine

Mantle cell lymphoma (MCL) is an incurable B-cell malignancy characterized by genetic dysregulation of cyclin D1 and activation of signaling pathways driving uncontrolled MCL cell proliferation and survival. Ibrutinib is an FDA-approved irreversible inhibitor of Bruton's tyrosine kinase (BTK), a downstream target of the B-cell receptor (BCR) pathway. While ibrutinib exhibits significant single-agent therapeutic activity in patients with relapsed/refractory MCL, the vast majority of MCL patients on ibrutinib progress with aggressive disease and short survival (3-8 mo). Although ~80% of chronic lymphocytic leukemia patients with acquired ibrutinib resistance have mutations in BTK and PLCγ2, this is uncommon in MCL suggesting alternative mechanisms driving this resistant phenotype. Understanding drug-resistance mechanisms and developing effective therapies for ibrutinib resistant (IR) MCL are urgently needed. The major type II protein arginine methyltransferase enzyme, PRMT5, catalyzes symmetric dimethylation of arginine residues on histone tails (H3R8 and H4R3) and other proteins. PRMT5 regulates a vast array of biologic functions including RNA processing, DNA damage response, signal transduction, and gene expression. Amplified PRMT5 activity drives the expression and activity of key oncogenes (MYC, CYCLIND1, NOTCH1) while silencing expression and activity of tumor suppressors (ST7, RBL2, and p53). Our group has shown PRMT5 is overexpressed and dysregulated in MCL and strategies aimed at selectively targeting PRMT5 show anti-tumor activity in preclinical lymphoma models. Here we describe the development of a novel patient derived xenograft (PDX) of IR-MCL and explore PRMT5 inhibition as an alternative therapeutic option to circumvent IR. Peripheral blood mononuclear cells from a 75 yo male patient diagnosed with acquired classic IR-MCL were engrafted intravenously into NSG mice. After 5 passages, all mice engrafted with 107 MCL cells developed histologically confirmed MCL infiltrating kidney, lymph nodes, bone marrow, spleen and peripheral blood. Circulating human CD5+/CD19+ cells were detectable and quantifiable by flow cytometry by day 21 post-engraftment. Karyotype analysis confirmed the hallmark t(11;14)(q13;q32) of MCL while retaining nearly all cytogenetic abnormalities present in the patient's primary tumor including a deletion of chromosome 9, associated with deletion of MTAP, a therapeutic vulnerability for PRMT5-targeted therapy. Whole exome sequencing confirmed genomic stability with successive passages. Ex vivo cytotoxicity assays and protein pathway analysis further confirmed resistance to ibrutinib (IC50 >1 µM) with maintained hyper-phosphorylation of AKT (Ser473) and ERK (Thr202/Tyr204). Western blot analysis showed elevated levels of c-MYC, CYCLIND1, BCL2, and pERK. After validation of circulating disease at day 25 post engraftment, mice were treated with either a novel small molecule inhibitor of PRMT5 (PRT382, 10 mg/kg orally 4 days on 3 days off) or ibrutinib (75 mg/kg administered in drinking water, n=5 mice per treatment group). Treatment of this PDX model with PRT382 resulted in significantly decreased disease burden and improved median survival compared to control animals from 48 to 83 days, respectively (p=0.0045). We found no significant difference in survival (p= 0.6540) or circulating disease burden with ibrutinib therapy compared to control group. The full BTK occupancy of ibrutinib treated mice was validated using fluorescence resonance energy transfer-based assay. Ex vivo PDX MCL cells from PRT382-treated mice showed loss of symmetric dimethyl arginine with preservation of asymmetric dimethyl arginine levels, reduced H4(Sme2)R3 epigenetic marks, and elevated levels of BCL2, MYC, and pAKT/pERK. We developed a cell line (SEFA) allowing for in vitro mechanistic studies. We are currently investigating potential mechanisms responsible for circumventing IR-MCL by integrating genome-wide changes to chromatin accessibility and whole transcriptome analysis. This IR-MCL PDX mouse model serves as a useful tool to investigate mechanisms of drug resistance, provides a platform to explore novel pre-clinical therapeutic strategies to circumvent IR and demonstrates the therapeutic activity of PRMT5 targeted therapy in this aggressive disease. Disclosures Byrd: Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Ohio State University: Patents & Royalties: OSU-2S; Genentech: Research Funding; BeiGene: Research Funding; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Novartis: Other: Travel Expenses, Speakers Bureau; Genentech: Research Funding; Acerta: Research Funding; Acerta: Research Funding; Ohio State University: Patents & Royalties: OSU-2S; BeiGene: Research Funding; Genentech: Research Funding; BeiGene: Research Funding; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Novartis: Other: Travel Expenses, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Novartis: Other: Travel Expenses, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Acerta: Research Funding; Ohio State University: Patents & Royalties: OSU-2S; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau. Vaddi:Prelude Therapeutics: Employment. Scherle:Prelude Therapeutics: Employment. Baiocchi:Prelude: Consultancy.

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Sensitivity of Ibrutinib Exposed Chronic Lymphocytic Leukemia B-Cells to Inhibition of Axl Receptor Tyrosine Kinase

Blood ◽

10.1182/blood.v128.22.2020.2020 ◽

2016 ◽

Vol 128 (22) ◽

pp. 2020-2020

Author(s):

Sutapa Sinha ◽

Justin C Boysen ◽

Kari G. Chaffee ◽

Brian F Kabat ◽

Susan L. Slager ◽

...

Keyword(s):

B Cells ◽

Board Of Directors ◽

Research Funding ◽

Lymphocytic Leukemia ◽

Employment Equity ◽

Advisory Committees ◽

Mutation Status ◽

Axl Receptor Tyrosine Kinase ◽

Equity Ownership

Abstract Introduction: The use of B-cell receptor (BCR) signal inhibitors-based therapies (e.g., Ibrutinib) for B-chronic lymphocytic leukemia (CLL) was initiated just a few years ago but has rapidly escalated due to their clinical efficacy and relative ease of use. However newer therapeutic approaches are needed due to multiple issues including the continued need to improve complete responses and reduce toxicity profiles. To that end our group has discovered a novel membrane target in the ubiquitous presence of Axl receptor tyrosine kinase (Axl RTK) on CLL B-cells and has reported that the Axl RTK inhibitor TP-0903 is able to induce apoptosis of CLL B-cells at nanomolar doses (Sinha, Clin Cancer Res, 2015). Given this we assessed if TP-0903 would be effective in the induction of apoptosis of leukemic B-cells from CLL patients who are currently on Ibrutinib therapy or whom have relapsed while on Ibrutinib treatment. Methods: Relapsed/refractory CLL patients (n=22) who were placed on Ibrutinib for progressive disease provided blood samples at a median of 3.2 months after Ibrutinib therapy initiation for these studies. We also obtained sequential samples on 8 patients from initial start of ibrutinib therapy and then over a 6 month follow-up period. CLL B-cells from these blood samples were subject to Ficoll separation, purified by using a Rosette Sep B-cell enrichment kit and then studied by flow cytometry to determine Axl RTK expression levels by flow cytometric analysis. Purified CLL B-cells (CD19+/CD5+) were cultured with TP-0903 in vitroat increasing doses (0.01µM - 0.50µM) for 24 hours and the LD50 dose was determined. In addition, 3 CLL patients who had been on Ibrutinib therapy and had a documented relapse were studied in similar fashion using TP-0903. LD50-sensitivity was measured. "LD50-sensitivity" was defined as an LD50 ≤0.50µM and "insensitive" was defined as an LD50 dose >0.50µM. CLL prognostic factors (e.g., FISH, IGHV mutation status, Rai stage, CD38, and CD49d) were evaluated at the time of ibrutinib treatment. Differences in factors between sensitive and insensitive cases were computed using the Kruskal-Wallis test for continuous variables and Chi-square test for categorical variables. Results: Twenty-two CLL patients (5 female, 17 male) were included in the analysis. Fourteen (64%) patients were found to be TP-0903 LD50-sensitive. Axl expression on CLL B-cells for this cohort was heterogeneous with a median of CD19+/CD5+ cells positive for Axl at 69.9% (range of 2.7-91.3%). The sensitive subjects tended to be younger with a median age at Ibrutinib treatment initiation of 62 vs 75.5 years (p=0.004). There were no significant differences in gender, FISH, IGHV mutation status, CD38, CD49d, or Rai stage between the sensitive and insensitive LD50 groups. There were no significant differences in relation to median Axl expression on CLL B-cells (sensitive: 72.6%, range: 2.7-91.3%; insensitive: 41.5%, range: 16.5-83.1%; p=0.35). The median number of treatments prior to initiation of ibrutinib did not differ between sensitivity groups (sensitive: 2.53, range: 8-10; insensitive: 43.5, range 12-20; p=0.2833). Association for ZAP70+ CLL B-cells tended to have more apoptosis induction by TP-0903 (sensitive: 84.6% ZAP70+; insensitive: 42.9% ZAP70+; p=0.052). In 8 CLL patients that were studied sequentially while on Ibrutinib continued to express Axl or increased their Axl expression (n=2) over a 3-6 month follow-up period. Three CLL patients who had relapsed on Ibrutinib were sensitive to TP-0903 with LD50 values of ≤0.50µM. Summary: Here we find that CLL B-cells from over 60% of relapsed CLL patients on Ibrutinib therapy were highly sensitive to the high-affinity Axl inhibitor TP-0903 with induction of apoptosis at nanomolar doses (≤0.50µM). The sensitivity of CLL B-cells to TP-0903 appears to be independent of Axl expression levels and of the known CLL prognostic factors but more evident for younger patients and for ZAP70+ expression status. Given this level of activity for apoptosis induction of CLL B-cells by TP-0903 encourages the further testing of this drug in clinical trials for CLL patients. Disclosures Parikh: Pharmacyclics: Honoraria, Research Funding. Shanafelt:Pharmacyclics: Research Funding; Janssen: Research Funding; Genentech: Research Funding; GlaxoSmithKline: Research Funding; Celgene: Research Funding; Cephalon: Research Funding; Hospira: Research Funding. Warner:Tolero Pharmaceuticals: Employment, Equity Ownership, Patents & Royalties. Bearss:Tolero Pharmaceuticals: Employment, Equity Ownership, Patents & Royalties. Kay:Pharmacyclics: Research Funding; Tolero Pharmaceuticals: Research Funding; Acerta: Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees; Morpho-Sys: Membership on an entity's Board of Directors or advisory committees; Infinity Pharm: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees.

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The Bruton’s Tyrosine Kinase (BTK) Inhibitor Ibrutinib (PCI-32765) Monotherapy Demonstrates Long-Term Safety and Durability Of Response In Chronic Lymphocytic Leukemia (CLL)/Small Lymphocytic Lymphoma (SLL) Patients In An Open-Label Extension Study

Blood ◽

10.1182/blood.v122.21.4163.4163 ◽

2013 ◽

Vol 122 (21) ◽

pp. 4163-4163 ◽

Cited By ~ 5

Author(s):

Susan O'Brien ◽

Richard R. Furman ◽

Nathan Fowler ◽

Steven E. Coutre ◽

Jeff P. Sharman ◽

...

Keyword(s):

Board Of Directors ◽

Research Funding ◽

Lymphocytic Leukemia ◽

Extension Study ◽

First Year ◽

Employment Equity ◽

Advisory Committees ◽

Equity Ownership ◽

Grade 3

Abstract Background Bruton’s Tyrosine Kinase (BTK) plays a critical role in chronic lymphocytic leukemia (CLL) cell survival by modulating B-cell receptor signaling. Ibrutinib (PCI-32765), a first-in-class oral inhibitor of BTK, inhibits proliferation, migration and adhesion in CLL cells. A total of 148 patients with CLL/SLL received ibrutinib monotherapy in a Phase 1 multiple ascending dose study (PCYC-04753) or Phase 1b/2 continuous dosing study (PCYC-1102-CA), after which a long-term extension study was available for continued follow-up for safety and efficacy with daily orally-administered ibrutinib monotherapy. The studies included patients with treatment-naïve (TN) and relapsed or refractory (RR) CLL/SLL. The aims of the present analysis were to evaluate safety based on time on ibrutinib therapy (≤ 1 year and > 1 year), summarize safety findings in the TN and RR patient populations, and assess duration of response (DOR). Methods Demographics and baseline characteristics were summarized according to parent study, comprising either TN patients or RR CLL/SLL patients who had received at least one dose of ibrutinib monotherapy. Patient disposition, treatment-emergent adverse events (AEs), best response, overall response rate (ORR), and DOR were determined for the time treated (beginning in the parent studies and extending into the long-term extension study). Results At a median treatment duration of 21.5 months, 109 out of 148 patients continued treatment with ibrutinib for over a year. The percentage of patients who had a grade 3 or higher serious adverse event (SAE) declined over time from 43% within the first year of study treatment to 32% after the first year of treatment. With respect to side effects determined to be related to study drug, the number of grade 3 AEs and SAEs also declined from within the first year of treatment (24% and 8%, respectively) to after the first year of treatment (7% and 0%, respectively). AEs leading to ibrutinib discontinuation occurred in 12 patients within the first year of treatment for all 148 patients and in 6 out of 109 patients after the first year of treatment. Overall, the most frequent AEs grade 3 or higher were pneumonia (16.9%), hypertension (13.5%), neutropenia (11.5%), thrombocytopenia (7.4%), and diarrhea (5.4%), regardless of relationship to study drug. Grade 3 or higher SAEs were reported in RR patients at 62% compared to TN patients at 29%. Pneumonia was reported in TN patients at 6.5% and in RR patients at 19.7%. Within the efficacy population (n = 140), the ORR was 86.2% for TN patients and 88.3% for RR patients who achieved a partial response (PR) or better. The ORR combined with PR with lymphocytosis suggests that 93.1% of TN patients and 93.7% of RR patients achieved an objective response to ibrutinib therapy based on Cheson JCO 2012. After a median follow up of 27.2 months (range 1.9-42 months) for TN and RR responders who achieved PR or better, the median DOR has not been reached. At landmark 30 months, 76.1% of the responders were alive without progression. Conclusions Ibrutinib as a single agent demonstrates long-term safety, tolerability, and durability of response in patients with TN and RR CLL/SLL. Indeed, a decrease in the number of patients experiencing SAEs or AEs grade 3 or higher after 1 year of treatment with ibrutinib resulted in low rates of treatment-related discontinuation after that time point. Grade 3 or higher SAEs were reported at a two-fold higher rate in patients who had received prior therapies, which may be reflective of disease state rather than relationship to ibrutinib. A majority of patients remain on ibrutinib monotherapy with the median DOR not yet reached in the ongoing extension study. Disclosures: O'Brien: Pharmacyclics: Research Funding. Furman:Genentech: Consultancy, Speakers Bureau; GlaxoSmithKline: Consultancy, Speakers Bureau; Pharmacyclics: Consultancy; Gilead: Consultancy. Fowler:Pharmacyclics: Membership on an entity’s Board of Directors or advisory committees, Research Funding. Coutre:Pharmacyclics: Consultancy, Research Funding. Burger:Pharmacyclics: Consultancy, Membership on an entity’s Board of Directors or advisory committees. Jones:Pharmacyclics: Membership on an entity’s Board of Directors or advisory committees, Research Funding. Wierda:Abbott Laboratories: Research Funding; Celgene: Consultancy, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; GlaxoSmithKline: Research Funding, Speakers Bureau; Genentech/Roche: Consultancy, DSMB, DSMB Other, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; Merck: Consultancy, Membership on an entity’s Board of Directors or advisory committees; Sanofi-Aventis: Consultancy, Membership on an entity’s Board of Directors or advisory committees; Tragara: Research Funding. Flinn:Pharmacyclics: Research Funding. Advani:Pharmacyclics: Research Funding; Janssen: Research Funding. Kolibaba:Pharmacyclics: Research Funding. Shaw:Pharmacyclics: Employment, Equity Ownership. Clow:Pharmacyclics: Employment, Equity Ownership. James:Pharmacyclics: Employment, Equity Ownership. Chu:Pharmacyclics: Employment, Equity Ownership. Byrd:Celgene: Consultancy; Johnson and Johnson: Consultancy; Pharmacyclics: Research Funding.

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