Multi-Institution Review of Adult Early T-Cell Precursor Acute Lymphoblastic Leukemia/Lymphoma (ETP-ALL)

Abstract Background: The Early T-cell precursor (ETP) variant of acute lymphoblastic lymphoma/leukemia (ALL) is a recognized high risk variant, recognized by the absence of CD1a, with aberrant myeloid antigen expression (CD13, CD33, CD117, and CD34), and frequent absence of CD4 or CD8. Treatment intensification may improve outcome in this subset. We undertook a multi-center retrospective analysis to explore clinical features, treatment exposure, and outcomes in ETP ALL as compared to non-ETP variants. Methods Adult T-ALL/T-LBL cases were compiled from 3 high volume cancer centers between the years 2003-2015. Data collected included patient demographics, tumor characteristics (white count at diagnosis, flow cytometry, FISH, cytogenetics, bone marrow involvement), treatment regimens and patient outcomes. ETP cases were defined as definite (CD1a-/CD8-/myeloid+) or probable (CD1a unk/CD8-/myeloid+, or CD1a-/myeloid+ with CD4+ and/or CD8+). All other cases were defined as non-ETP. Demographic data were compared using independent t-test assuming non-equal variance. OS and PFS were calculated from diagnosis and compared by Kaplan Meier and log-rank testing. Results Among 95 cases, 33 met criteria for definite/probable ETP (35%). OS and PFS data were indistinguishable between these groups (p=0.24, p=0.34), and were subsequently analyzed as a single group. Within the ETP group, no factors were associated with OS, including histology (CD1a+ vs unk, CD3cyt vs CD3sur, CD5dim vs CD5+, CD1a+/13+ vs CD1a+/13-, or CD13, CD33, CD117, CD34, & TdT status), marrow blast burden, peripheral blast burden, white blood cell count (wbc), hemoglobin (hgb), platelet count (plt), cytogenetics/FISH status, chemotherapy choice, or allogeneic transplant (in CR1 or at any time). With regards to PFS, only the inclusion of asparaginase with induction was associated with outcome (p=0.009), while all other covariates failed to show any significance. The ETP group was compared with the non-ETP subset (table 1). ETP were more likely to abuse marijuana, possibly reflecting unrecognized pesticide exposure, and were more likely to abnormalities of chrom 5 & 7. ETP trended towards lower response and higher rate of relapse, with lower PFS. Comparison of OS was not significant, likely related to small numbers (5y OS 37% vs 22%, figure 1). Non-ETP failed to show PFS benefit with frontline asparaginase, otherwise no treatment differences were apparent. Conclusions In this muti-center cohort we were able to identify and characterize ETP cases, confirming poor outcomes. Improvement in PFS among ETP patients treated with frontline asparaginase warrants attention and prospective confirmation. Unfortunately, OS remains poor independent of treatment or receipt of allogeneic transplant, suggesting a critical need remains for development and study novel therapies. Table 1. ETP Non-ETP p-value Median Age 37.45 34.74 0.42 Male 82% 66% 0.89 FamilyHx of Lymph/Leuk 21% 8% 0.112 FamilyHx of Ca 42% 25% 0.09 THC 24% 5% 0.021 P blasts 40% 28% 0.158 >25% M blasts 30% 55% 0.0571 WBC 78.45 76.55 0.948 wbc>100 24% 24% 0.995 Hgb 10.72 11.78 0.148 hgb<12 67% 47% 0.097 plt 151.59 138.66 0.644 Chrom 5/7 40% 7% 0.005 Remission 61% 79% 0.096 Relapse 76% 58% 0.073 OS 27.00 22.00 0.595 PFS 13.00 17.00 0.048 PFS Asp ETP (asp no vs yes) 12 59 0.009 non-ETP (asp no vs yes) 17 15 0.777 Figure 1. Figure 1. Disclosures Shah: Acetylon: Membership on an entity's Board of Directors or advisory committees; Spectrum: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bayer: Honoraria; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; PLexus Communications: Honoraria; Pharmacyclics: Speakers Bureau; Rosetta Genomics: Research Funding; Seattle Genetics: Research Funding. Kota:Pfizer: Membership on an entity's Board of Directors or advisory committees; Leukemia Lymphoma Society: Research Funding. Hathaway:OnQ Health: Research Funding.

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Genetic Characteristics and Clinical Outcomes of T-Cell Acute Lymphoblastic Leukemia; Myeloid-Suppressive Therapeutic Approach Based on Allogeneic Hematopoietic Cell Transplantation May Benefit in Early T-Cell Precursor Acute Lymphoblastic Leukemia

Blood ◽

10.1182/blood-2019-129870 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1470-1470

Author(s):

Jae-Ho Yoon ◽

Han Bi Lee ◽

Gi June Min ◽

Sung-Soo Park ◽

Silvia Park ◽

...

Keyword(s):

Acute Lymphoblastic Leukemia ◽

T Cell ◽

Board Of Directors ◽

Clinical Outcomes ◽

Cell Transplantation ◽

Research Funding ◽

Hematopoietic Cell Transplantation ◽

Lymphoblastic Leukemia ◽

Cell Precursor ◽

Advisory Committees

Background: Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is a recently recognized high-risk subgroup of T-cell ALL. T-cell ALL is characterized by poorer survival outcomes compared to B-cell ALL, but the optimal treatment strategies are not well elucidated yet. Aim: We performed integrative genetic analyses and tried to find important genetic events in T-cell ALL. We also identified clinical outcomes of T-cell ALL including ETP-ALL subgroup, which were treated with myeloid-suppressive chemotherapy followed by allogeneic hematopoietic cell transplantation (allo-HCT) for post-remission therapy. Methods: We enrolled 40 adult patients with T-cell ALL for analyses of gene mutations and treatment outcomes. Integrative genetic analyses were performed with massive parallel sequencing for NOTCH1, FBXW7, DNMT3A, PHF6, RUNX1, KRAS, NRAS, PTEN, GATA3, EZH2 and SH2B3, and multiplex ligation-dependent probe amplification (MLPA) for copy number alterations of several genes. Among them, quantification of CDKN2A and CDKN2B mRNA expression was performed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). All were treated with myeloid-suppressive chemotherapy which consisted of hyper-fractionated cyclophosphamide (300 mg/BSA, every 12 h, days 1-3), vincristine (1.4 mg/BSA, maximum dose 2 mg, days 4 and 11), daunorubicin (45 mg/m2, days 4 and 11), and dexamethasone (40 mg, days 1-4 and days 11-14) for remission induction, followed by consolidation with high-dose cytarabine (2 g/BSA, every 12 h, days 1-5) and mitoxantrone (12 mg/BSA, days 1-2). Above two anthracycline-intensified regimens were alternatively used for further consolidation. For patients not in complete remission (CR), mitoxantrone (12 mg/BSA, d 1-4), cytarabine (2 g/BSA, every 12 h, d 1-4) and etoposide (100 mg/BSA, d 5-7) were used for reinduction. Our strategy for T-cell ALL in CR was to offer allo-HCT according to the donor availability. Results: We identified 16 patients with ETP-ALL presenting 1 or more stem cell or myeloid marker with absence of CD1a, CD5, and CD8 expression, and 24 patients with non-ETP-ALL. For genetic mutation profiles between ETP-ALL and non-ETP-ALL, we found DNMT3A was more frequently observed in ETP-ALL (25% vs. 12.5%), while FBXW7 (33.3% vs. 6.2%) and RUNX1 (25.0% vs. 0.0%) were more frequently observed in non-ETP-ALL. We also observed that CDKN2A expression was significantly higher in ETP-ALL (0.053 vs. 0.001, p=0.017). In total, 33 (82.5%) patients achieved CR (24 after induction, 9 after reinduction) and their estimated 5-year overall survival (OS) was 31.3% with median survival of 18.9 months. All 16 (100%) patients with ETP-ALL achieved CR (13 after induction, 3 after reinduction), while non-ETP-ALL in 17 (70.8%, 11 after induction, 6 after reinduction) patients. Estimated 5-year OS of ETP-ALL was 41.7% and non-ETP-ALL was 24.3% (p=0.135). Finally, 12 (75.0%) out of 16 ETP-ALL and 11 (45.8%) out of 24 non-ETP-ALL underwent allo-HCT in CR and their 5-year OS was 55.6% and 45.5%, respectively. Conclusion: Our data suggested different genetic predisposition between ETP-ALL and non-ETP-ALL and myeloid-suppressive chemotherapy showed a good CR rate in ETP-ALL. Myeloid-suppressive chemotherapy induced CR followed by post-remission allo-HCT can be a good solution for improving poor survival outcome of ETP-ALL. Disclosures Kim: Celgene: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Hanmi: Consultancy, Honoraria; AGP: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; SL VaxiGen: Consultancy, Honoraria; Novartis: Consultancy; Amgen: Honoraria; Chugai: Honoraria; Yuhan: Honoraria; Sanofi-Genzyme: Honoraria, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Handok: Honoraria; Janssen: Honoraria; Daiichi Sankyo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Otsuka: Honoraria; BL & H: Research Funding. Lee:Alexion: Consultancy, Honoraria, Research Funding; Achillion: Research Funding.

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Early Allogeneic Stem Cell Transplantation and Use of Asparaginase during Induction Chemotherapy Appear to Improve Otherwise Poor Outcomes in Adult T-Cell Acute Lymphoblastic Leukemia/Lymphoma (T-ALL/T-LBL) Patients: A Multi-Institutional Review

Blood ◽

10.1182/blood.v126.23.4869.4869 ◽

2015 ◽

Vol 126 (23) ◽

pp. 4869-4869 ◽

Cited By ~ 1

Author(s):

Uma Borate ◽

Amanda Redden Hathaway ◽

Deniz Peker ◽

Bradford E Jackson ◽

Vamsi K Kota ◽

...

Keyword(s):

Board Of Directors ◽

Treatment Regimen ◽

Research Funding ◽

Lymphoblastic Leukemia ◽

Rank Test ◽

P Value ◽

Advisory Committees ◽

Treatment Regimens ◽

Genetics Research ◽

Institutional Review

Abstract Background: AdultT-cell acute lymphoblastic leukemia/lymphoma (T-ALL/T-LBL) is a rare, aggressive bone marrow malignancy with a historically poor prognosis despite use of various chemotherapies. Methods: After institutional review board approval, we compiled a database of all adult T-ALL/T-LBL cases at three large cancer centers between the years 2005-2015, treated at the physician's discretion. Data collected included patient demographics, tumor characteristics (white cell count at diagnosis, blast phenotype, FISH, cytogenetics, bone marrow involvement), treatment regimens and patient outcomes. Relapse-free survival (RFS) and overall survival (OS) were examined looking at medians and interquartile ranges of times to events. Kaplan Meier curves provided a graphical representation of the survival probability. Moreover, we provided estimates of the 50th percentile along with corresponding 95% confidence intervals (CIs). We also used Univariate and Multivariable Cox Regression to estimate unadjusted and adjusted Hazard Ratios (HRs) and their 95% CIs. Stratified analysis was also performed using the Mann-Whitney U-test to compare median survival times, and the Log-rank to compare survival curses for RFS and OS. Results: The final analysis included 95 adult patients. Median age at diagnosis was 32 (range 17-75). 71.6% of patients were male. 49.5% of patients were white, 14.7% were black, 6.3% were Hispanic, 7.4% were Asian and in 22.1% of patients the race was unknown. Multiple frontline treatment regimens were used with 60% of patients treated with Hyper-CVAD, an additional 5.3% of patients received Hyper-CVAD with asparaginase, 24.2% of patients were treated on a pediatric-based protocol, 4.2% on a clinical trial, and 6.3% received other regimens. In total, 40 patients (42.1%) received asparaginase at some point during treatment regimen with 27 patients (28.4%) receiving it in the initial treatment regimen. After induction therapy, 65 patients (68.4%) achieved remission. Twenty-eight patients (29.5%) underwent transplant (8 matched-related donors, 10 matched unrelated donors, 5 mismatched unrelated donor, 2 cord transplants, 2 autologous, and 1 haplo-identical transplant). Ten patients (10.5%) underwent transplant in first complete remission (CR1) while two patients (2.1%) proceeded to transplant with minimal residual disease following induction. Despite therapy, 59 patients (62.1%) had known disease relapse or progressive disease. 16 patients (16.8%) underwent transplant after disease relapse. At time of analysis, 57 patients (60.6%) died. In the entire cohort, median RFS was 12.9 months and median OS was 19 months. In patients with a very high white count (>100 x 103/cmm at presentation) there was a trend toward earlier relapse when compared to patients presenting with white counts in the normal range (HR 2.27, p-value 0.085). Patients who received asparaginase in their initial treatment regimen have statistically improved RFS (HR 2.65, p-value = 0.014) and OS (HR 2.3, p-value=0.017). When adjusting for the presence of the covariates of age, sex, and WBC, patients who received initial asparaginase still had significant improvement in RFS (HR 3.18, p-value 0.033). In overall survival, significant benefit was seen in the addition of asparaginase in patients under 40 (HR 3.4, CI 1.22-9.5), however in patients greater than 40, asparaginase use seemed to decrease survival (HR 0.24, CI 0.03-1), although this did not reach statistical significance. All patients who underwent transplant had an improvement in OS, with median survival in the transplant group of 27 months compared to 18.2 months in the non-transplanted patients (log-rank test p-value = 0.048). Patients who received a transplant in CR1 had a trend towards improvement in RFS of 6.3 months (17.8 months versus 11.5 months in non-transplanted patients; log-rank test p-value = 0.03). Conclusion: Overall, adult T-ALL/T-LBL has a poor prognosis. Our multi-institutional retrospective review showed that OS and RFS may be improved by incorporating asparaginase use in front line therapy and by transplanting patients in first CR. Our data is limited in that actual dosing of asparaginase was not examined and that relatively few patients > 40 yrs old received asparaginase (4 pts) or SCT (5 pts). More prospective studies are needed in older adult T-ALL/LBL patients using these approaches to possibly improve their outcomes. Disclosures Borate: Gilead: Speakers Bureau; Genoptix: Consultancy; Seattle Genetics: Research Funding; Novartis: Speakers Bureau; Amgen: Speakers Bureau; Alexion: Speakers Bureau. Hathaway:OnQ Health: Research Funding. Kota:Pfizer: Membership on an entity's Board of Directors or advisory committees; Leukemia Lymphoma Society: Research Funding. Shah:DeBartolo Institute for Personlaized Medicine: Research Funding; Rosetta Genomics: Research Funding; Acetylon Pharmaceuticals, INC: Membership on an entity's Board of Directors or advisory committees; Plexus Communications: Honoraria; Pharmacyclics: Speakers Bureau; Spectrum: Speakers Bureau; Bayer: Honoraria; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Speakers Bureau; Seattle Genetics: Research Funding; SWOG: Consultancy; NCCN: Consultancy. Jillella:Leukemia Lymphoma Society: Research Funding. Heffner:Amgen: Consultancy. Erba:Novartis; Incyte; Celgene: Consultancy, Patents & Royalties; GlycoMimetics; Janssen: Other: Data Safety & Monitoring Committees; Seattle Genetics; Amgen: Consultancy, Research Funding; Millennium/Takeda; Celator; Astellas: Research Funding; Sunesis;Pfizer; Daiichi Sankyo; Ariad: Consultancy.

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T-Cell Suppression By Src/ABL Kinase Inhibitors When Combined with Blinatumomab in Ph+ Acute Lymphoblastic Leukemia

Blood ◽

10.1182/blood-2018-99-119301 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 2694-2694 ◽

Cited By ~ 1

Author(s):

Jessica Leonard ◽

Yoko Kosaka ◽

Pavani Malla ◽

Brandon Hayes-Lattin ◽

Adam J. Lamble ◽

...

Keyword(s):

T Cell ◽

Board Of Directors ◽

Research Funding ◽

Kinase Inhibitors ◽

Cell Function ◽

Lymphoblastic Leukemia ◽

Advisory Committees ◽

Abl Kinase ◽

Equity Ownership ◽

Abl Kinase Inhibitors

Abstract Introduction: Targeted ABL kinase inhibitors (TKIs) have shown great activity in Ph+ Acute Lymphoblastic Leukemia (Ph+ ALL), however relapsed disease remains an unmet need. The bispecific antibody blinatumomab was recently approved as a single agent for use in patients with Ph+ ALL and there is much interest in combining this with targeted therapies. Second generation ABL kinase inhibitors inhibit both Src and LYN in addition to ABL. This is of particular interest in Ph+ ALL as LYN is important for leukemogenesis. T cell receptor (TCR) signaling is also dependent upon Src family kinase activity, and Src inhibitors may impact the efficacy of immunotherapies reliant on native T cell function. We sought to investigate the in vitro effects of ABL specific vs dual Src/ABL kinases on blinatumomab efficacy in both healthy donor as well as primary patient samples. Methods: We isolated peripheral blood mononuclear cells (PBMC) via Ficoll-Hypaque gradient from five healthy donors as well as from two patients with de novo and one patient with relapsed Ph+ ALL who harbored a T315I mutation. PBMC were labeled with CellTrace Violet and cultured for 5 days with no stimulation, blinatumomab, or blinatumomab in combination with imatinib, dasatinib, ponatinib or nilotinib at varying concentrations. Immunophenotyping was performed using multi-parameter flow cytometry for the following cell surface markers: CD45, CD3, CD4, CD8, CD56, and CD19. Blinatumomab efficacy was assessed by comparing the numbers of CD19+ / CD3- cells in untreated samples to those that had been treated with blinatumomab in the presence or absence of TKIs. Cell division of T cells was measured by CellTrace Violet dilution. Cytokine production was assessed via LEGENDplex Human Th Cytokine Panel. Levels of total Src, phospho-Src, total LCK and phospho-LCK were assessed via immunoblot. Results: After 5 days of exposure, blinatumomab led to T-cell proliferation in both healthy donor and patient PBMCs. Proliferation was observed in both CD8+ and CD4+ T cell subsets, although the effect was more pronounced in CD8+ cells. T cell proliferation, however, was completely suppressed by either dasatinib or ponatinib at nanomolar concentrations. This effect was far less pronounced with the ABL kinase inhibitors imatinib and nilotinib. Treatment of PBMCs with blinatumomab led to increased production of the cytokines IFN-g, IL-17-a and IL-22 in patient samples and healthy donors, while levels of IL-6 were increased in the patient samples only and levels of IL-10 in healthy subjects only. Cytokine production was absent in samples treated with blinatumomab and either dasatinib or ponatinib, while levels of IFN-g, IL-17a and IL-22 were minimally affected when blinatumomab was combined with imatinib. Immunoblots confirmed that dasatinib and ponatinib but not imatinib nor nilotinib inhibited phosphorylation of total Src as well as of LCK, likely explaining the inhibitory effects of these agents. In patient samples, blinatumomab alone and the TKIs alone greatly reduced the number of CD19+ cells. However, when dasatinib and blinatumomab were combined in the sample with a T315I mutation, there was little reduction in the percentage of CD19+ cells and no amplification of CD3+ cells, suggesting that dasatinib was able to inhibit the cytotoxic effects of blinatumomab with no effect to the leukemic cells. Discussion: Our results suggest that the combination of dual Src/ABL inhibitors with blinatumomab may abrogate the effects of blinatumomab by directly inhibiting T cell function. This is likely via inhibition of LCK, a known member of the TCR signaling pathway. Although small case series have reported responses in patients treated with blinatumomab and TKIs, it is possible that the majority of the response is from the TKI rather than blinatumomab. Only a randomized trial of a TKI +/- blinatumomab would be able to discern whether there is benefit of adding a dual Src/ABL TKI to bispecific antibody therapy. While our data are limited by sample numbers and by the fact that responses in living subjects may differ according to many other complex interactions in the in vivo immune microenvironment, the potential immunomodulatory effects of targeted therapies should be taken into consideration before they are combined with immunotherapies. Disclosures Leonard: Amgen: Research Funding. Druker:McGraw Hill: Patents & Royalties; Fred Hutchinson Cancer Research Center: Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees; ARIAD: Research Funding; Monojul: Consultancy; Millipore: Patents & Royalties; Novartis Pharmaceuticals: Research Funding; Oregon Health & Science University: Patents & Royalties; Leukemia & Lymphoma Society: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Meyers Squibb: Research Funding; ALLCRON: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy; Gilead Sciences: Consultancy, Membership on an entity's Board of Directors or advisory committees; Blueprint Medicines: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Cepheid: Consultancy, Membership on an entity's Board of Directors or advisory committees; Beta Cat: Membership on an entity's Board of Directors or advisory committees; MolecularMD: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Patient True Talk: Consultancy; Vivid Biosciences: Membership on an entity's Board of Directors or advisory committees; Third Coast Therapeutics: Membership on an entity's Board of Directors or advisory committees; GRAIL: Consultancy, Membership on an entity's Board of Directors or advisory committees; Aileron Therapeutics: Consultancy; Henry Stewart Talks: Patents & Royalties; Aptose Therapeutics: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Tyner:Constellation: Research Funding; Vivid Biosciences: Membership on an entity's Board of Directors or advisory committees; Janssen: Research Funding; Gilead: Research Funding; Aptose: Research Funding; Incyte: Research Funding; Genentech: Research Funding; Array: Research Funding; Takeda: Research Funding; AstraZeneca: Research Funding. Lind:Celgene: Research Funding; Janssen Pharmaceutical R&D: Research Funding; Amgen: Research Funding; Fluidigm: Honoraria; Monojul: Research Funding.

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A Single-Arm, Open-Label Phase 2 Pilot Study of Vyxeos (CPX-351) in Adults with Relapsed or Refractory Acute Lymphoblastic Leukemia

Blood ◽

10.1182/blood-2021-151936 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 4399-4399

Author(s):

Bijal D. Shah ◽

Nicole Rozario ◽

Elyce P. Turba ◽

Celeste Bello ◽

Julio C. Chavez ◽

...

Keyword(s):

Acute Lymphoblastic Leukemia ◽

Board Of Directors ◽

Research Funding ◽

Tp53 Mutation ◽

Lymphoblastic Leukemia ◽

Pilot Trial ◽

Refractory Disease ◽

Allogeneic Transplant ◽

Advisory Committees ◽

Grade 3

Abstract Introduction: Vyxeos® is a liposomal formulation employing a 1:5 molar ratio of daunorubicin:cytarabine. Clinical trials in high risk acute myeloid leukemias demonstrated a significant benefit in CR rates and median OS, culminating in FDA approval August 2017. Emerging pediatric data suggest this benefit may extend to acute lymphoblastic leukemia (ALL). The following pilot trial was performed to better understand the activity and toxicity profile in adults with relapsed and refractory ALL. Methods: Adults with ALL or mixed phenotype leukemia were eligible if >5% lymphoblasts and/or extramedullary disease >1x1cm. Induction consisted of Vyxeos 100 units/m2 on days 1, 3 and 5. Those with clinical benefit could receive up to 3 cycles of consolidation delivered at 65 units/m2 on days 1 & 3 after recovery of neutrophils (>500 cells/uL) and platelets (>50,000 cells/uL). Response: 11 patients (pts) have been treated to date, with median age of 39y (22-74y), 9 male, and 3 Caucasian. Six pts had B-ALL, including 1 B-myeloid. Four of 5 T-ALL pts had early T-cell precursor (ETP) phenotype. NGS was available in 9 pts, and included TP53 mutation (n=4), and PH-like changes (n=2). Median prior lines of therapy was 3, with 7 pts showing primary refractory disease. Prior blinatumomab, inotuzumab, CAR-T cell therapy, and allogeneic transplant were noted in 5, 2, 1, and 3 pts. Pancytopenia was uniform during induction, with febrile neutropenia noted in 9 pts. One pt passed from pneumonia after moving to comfort measures in lieu of intubation 20 days after Vyxeos, and is non-evaluable for response. A second pt developed grade 3 sepsis. The remainder of infections were grade 1-2. One pt had grade 3 gastrointestinal bleed, and 3 pts had grade 1 spontaneous subdural bleeding. One pt developed recurrent pericarditis in setting of anterior mediastinal mass. One case of veno-occlusive disease was observed in a pt with prior allogeneic transplant and inotuzumab. Median time to ANC recovery was 33.5 days among 10 evaluable pts. Two pts with refractory disease failed to recover platelets; among the remaining pts, median time to platelet recovery was 30.5 days. Adverse events were uncommon during consolidation, and include foot cellulitis and myopericarditis, each in 1 pt. Among 10 evaluable pts, 3 achieved CR/CRi, including 2 ETP T-ALL and one B-ALL. Two pts with TP53 mutation demonstrated >50% blast reduction with hematologic recovery, allowing for prolonged time to subsequent therapy. Four pts received 1-3 cycles consolidation. One pt was bridged to donor leukocyte infusion. Responses were noted in only 2 pts after progression following Vyxeos, highlighting refractory status of those enrolled. Median PFS was 57 days (95%CI: 10, 105), time to next therapy 76 days (95%CI: 47, 105), and OS 223 days (95%CI: 144, 302). Conclusions Vyxeos in high-risk refractory adult ALL was overall well tolerated and active, with median OS of approximately 7.5 months in this pilot trial. Confirmation of benefit in a larger study is warranted, incorporating a second induction course and/or the addition of novel agents to further improve on remission rate and duration of response. Disclosures Shah: Incyte: Research Funding; Jazz Pharmaceuticals: Research Funding; Servier Genetics: Other; BeiGene: Consultancy, Honoraria; Acrotech/Spectrum: Honoraria; Pharmacyclics/Janssen: Honoraria, Other: Expenses; Kite, a Gilead Company: Consultancy, Honoraria, Other: Expenses, Research Funding; Precision Biosciences: Consultancy; Amgen: Consultancy; Novartis: Consultancy, Other: Expenses; Pfizer: Consultancy, Other: Expenses; Bristol-Myers Squibb/Celgene: Consultancy, Other: Expenses; Adaptive Biotechnologies: Consultancy. Chavez: Astra Zeneca: Research Funding; Novartis: Consultancy; Merck: Research Funding; Morphosys: Speakers Bureau; Adaptive Biotech: Research Funding; ADC Therapeutics: Consultancy, Research Funding; Beigene: Speakers Bureau; Kite/Gilead: Consultancy; karyopharm: Consultancy; Epizyme: Speakers Bureau; Abbvie: Consultancy. Sokol: Dren Bio: Membership on an entity's Board of Directors or advisory committees; Kyowa-Kirin: Membership on an entity's Board of Directors or advisory committees. Lancet: Celgene/BMS: Consultancy; Millenium Pharma/Takeda: Consultancy; Daiichi Sankyo: Consultancy; AbbVie: Consultancy; BerGenBio: Consultancy; ElevateBio Management: Consultancy; Agios: Consultancy; Astellas: Consultancy; Jazz: Consultancy. OffLabel Disclosure: Vyxeos is being evaluated in the described trial for the treatment of relapsed or refractory acute lymphoblastic leukemia in adults.

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Amino Acid Stress Response Genes Promote L-Asparaginase Resistance in Pediatric Acute Lymphoblastic Leukemia

Blood ◽

10.1182/blood-2021-152940 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 3304-3304

Author(s):

Daniel Ferguson ◽

J. Robert McCorkle ◽

Qian Dong ◽

Erik Bonten ◽

Wenjian Yang ◽

...

Keyword(s):

Board Of Directors ◽

Cell Lines ◽

Research Funding ◽

Lymphoblastic Leukemia ◽

Acid Stress ◽

Leukemia Cells ◽

P Value ◽

Newly Diagnosed ◽

Advisory Committees ◽

Primary Leukemia

Abstract Understanding the genomic and epigenetic mechanisms of drug resistance in pediatric acute lymphoblastic leukemia (ALL) is critical for further improvements in treatment outcome. The role of transcriptomic response in conferring resistance to l-asparaginase (LASP) is poorly understood, beyond asparagine synthetase (ASNS). We defined reproducible LASP response genes in LASP resistant and sensitive ALL cell lines (n = 7) as well as primary leukemia samples from newly diagnosed patients. We identified 2219 response genes (absolute log 2FC > 1.5, FDR p-value <0.05) with ~16.5% being reproduced in more than one cell line. Defining target genes of the amino acid stress response related transcription factor ATF4 in ALL cell lines using ChIP-seq revealed 25% of genes that changed expression after LASP treatment were direct targets of the ATF4 transcription factor. A total of 17,117 significantly differentially bound ATF4 sites were identified (FDR p-value <0.01) and 97.8% of these sites displayed an increase in ATF4 binding following LASP treatment. SLC7A11 was found to be a response gene in cell lines and patient samples as well as a direct target of ATF4. SLC7A11 was also one of only 2.4% of response genes with basal level gene expression that also correlated with LASP ex vivo resistance in primary leukemia cells from 212 newly diagnosed children enrolled on St. Jude Total Therapy 16. Experiments using chemical inhibition of SLC7A11 with sulfasalazine, gene overexpression, and partial gene knockout recapitulated LASP resistance or sensitivity in ALL cell lines. These findings show the importance of assessing changes in gene expression following treatment with an antileukemic agent for its association with drug resistance and highlights that many response genes may not differ in their basal expression in drug resistant leukemia cells. Disclosures Stock: Pfizer: Consultancy, Honoraria, Research Funding; amgen: Honoraria; agios: Honoraria; jazz: Honoraria; kura: Honoraria; kite: Honoraria; morphosys: Honoraria; servier: Honoraria; syndax: Consultancy, Honoraria; Pluristeem: Consultancy, Honoraria. Mullighan: Amgen: Current equity holder in publicly-traded company; Illumina: Membership on an entity's Board of Directors or advisory committees; AbbVie: Research Funding; Pfizer: Research Funding. Pui: Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; Novartis: Other: Data Monitoring Committee. Evans: Princess Máxima Center for Pediatric Oncology, Scientific Advisory Board, Chair: Membership on an entity's Board of Directors or advisory committees; BioSkryb, Inc.: Membership on an entity's Board of Directors or advisory committees; St. Jude Children's Research Hospital, Emeritus Member (began Jan 2021): Ended employment in the past 24 months.

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Clinical Efficacy of Anti-CD22 Chimeric Antigen Receptor T Cells for B-Cell Acute Lymphoblastic Leukemia Is Correlated with the Length of the Scfv Linker and Can be Predicted Using Xenograft Models

Blood ◽

10.1182/blood.v130.suppl_1.807.807 ◽

2017 ◽

Vol 130 (Suppl_1) ◽

pp. 807-807

Author(s):

Marco Ruella ◽

Shannon L Maude ◽

Boris Engels ◽

David M. Barrett ◽

Noelle Frey ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Board Of Directors ◽

T Cell Activation ◽

Research Funding ◽

Cell Activation ◽

Lymphoblastic Leukemia ◽

Advisory Committees ◽

Xenograft Models

Abstract Introduction. Anti-CD19 chimeric antigen receptor T cells (CART19 or CTL019) have shown impressive clinical activity in B-cell acute lymphoblastic leukemia (B-ALL) and are poised to receive FDA approval. However, some patients relapse after losing CD19 expression. Since CD22 remains highly expressed in relapsed/refractory (r/r) B-ALL even in these patients, anti-CD22 CART (CART22) have been developed. The National Cancer Institute (NCI) reported 4/9 complete remission (CR) in patients receiving CART22, with 100% CR at the highest T cell dose (NCT02315612)(S hah NN, ASH 2016 #650). Patients and Methods. We generated a second-generation CAR22 differing from that used by the NCI only by the use of a longer linker [4x(GGGGS); LL vs. 1x(GGGGS); SL] between the light and heavy chains of the scFv (Fig. 1 A). This construct was tested in two pilot clinical trials in adults (NCT02588456)and children with r/r-ALL (NCT02650414). CART22 cells were generated using lentiviral transduction as in our previous studies. The protocol-specified CART22 dose was 2x106-1x107 cells/kg for pediatric patients <50kg and 1-5x108 for pediatric patients ≥50kg and adult patients,. infused after lymphodepleting chemotherapy. Patient characteristics are described in Table 1. For the adult trial, 5 patients were screened, 4 enrolled (1 patient withdrew consent) and 3 infused (1 manufacturing failure). For the pediatric trial, 9 patients were screened, 8 enrolled (1 screen failure) and 6 infused (two patients were not infused for disease progression). For the preclinical studies, we generated CART22LL and CART22SL and tested them in vivo using xenograft models. NOD-SCID gamma chain deficient (NSG) mice were engrafted with either a luciferase+ standard B-ALL cell line (NALM6) or primary B-ALL cells obtained from a patient relapsing after CART19 (CHP110R). We also used 2-photon imaging to study the in vivo behavior and immune synapse formation and flow cytometry to asses T cell activation. Results. CART22 cells were successfully manufactured for 10/12 patients. In the adult cohort 3/3 patients developed CRS (gr.1-3) and no neurotoxicity was observed; in the pediatric cohort out of 5 evaluable patients (1 discontinued for lineage switch to AML on pre-infusion marrow), 3/5 developed cytokine-release syndrome (CRS) (all grade 2) and 1 patient had encephalopathy (gr.1). CART22 cells expanded in the PB with median peak of 1977 (18-40314) copies/ug DNA at day 11-18. Interestingly, in an adult patient who had previously received CART19 a second CART19 re-expansion was observed following CART22 expansion (Fig 1 B). At day 28, in the adult cohort the patient who was infused in morphologic CR remained in CR, while the other 2 had no response (NR); in the pediatric cohort 2/5 patients were in CR, 1 in partial remission (PR) that then converted to CR with incomplete recovery at 2 months, and 2 NR. No CD22-negative leukemia progression was observed. Since our results with a long linker appeared inferior compared to the previously reported CART22 trial (short linker), we performed a direct comparison of the 2 different CAR22 constructs. In xenograft models, CART22SL significantly outperformed CART22LL (Fi 1 C) with improved overall survival. Moreover, CART22SL showed higher in vivo proliferation at day 17 (Fig 1 D). Mechanistically, intravital 2-photon imaging showed that CART22SL established more protracted T cell:leukemia interactions than did CART22LL, suggesting the establishment of productive synapses (Fig 1 E). Moreover, in vivo at 24 hrs higher T cell activation (CD69, PD-1) was observed in CART22SL from the BM of NALM-6-bearing mice. Conclusions. Here we report the results of two pilot clinical trials evaluating the safety and feasibility of CART22 therapy for r/r B-ALL. Although feasible and with manageable toxicity CART22LL led to modest clinical responses. Preclinical evaluation allowed us to conclude that shortening the linker by 15 amino acids significantly increases the anti-leukemia activity of CART22, possibly by leading to more effective interactions between T cells and their targets. Finally, with the caveats of cross-trial comparison, our data suggest that xenograft models can predict the clinical efficacy of CART products and validate the use of in vivo models for lead candidate selection Disclosures Ruella: Novartis: Patents & Royalties, Research Funding. Maude: Novartis Pharmaceuticals: Consultancy, Other: Medical Advisory Boards. Engels: Novartis: Employment. Frey: Novartis: Research Funding. Lacey: Novartis: Research Funding; Genentech: Honoraria. Melenhorst: Novartis: Research Funding. Brogdon: Novartis: Employment. Young: Novartis: Research Funding. Porter: Incyte: Honoraria; Novartis: Honoraria, Patents & Royalties, Research Funding; Immunovative Therapies: Other: Member DSMB; Genentech/Roche: Employment, Other: Family member employment, stock ownship - family member; Servier: Honoraria, Other: Travel reimbursement. June: WIRB/Copernicus Group: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celldex: Honoraria, Membership on an entity's Board of Directors or advisory committees; Immune Design: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Novartis: Patents & Royalties, Research Funding; Tmunity Therapeutics: Equity Ownership, Research Funding. Grupp: Jazz Pharmaceuticals: Consultancy; Novartis Pharmaceuticals Corporation: Consultancy, Other: grant; University of Pennsylvania: Patents & Royalties; Adaptimmune: Consultancy. Gill: Novartis: Patents & Royalties, Research Funding.

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Risk Factors Affecting Outcome of Transplantation in Pediatric Acute Lymphoblastic Leukemia: Results of the International BFM ALL SCT Study

Blood ◽

10.1182/blood.v126.23.2015.2015 ◽

2015 ◽

Vol 126 (23) ◽

pp. 2015-2015

Author(s):

Adriana Balduzzi ◽

Jean-Hugues Dalle ◽

Arjan C Lankester ◽

Isaac Yaniv ◽

Akif Yesilipek ◽

...

Keyword(s):

Acute Lymphoblastic Leukemia ◽

Board Of Directors ◽

Research Funding ◽

Acute Gvhd ◽

Lymphoblastic Leukemia ◽

Chronic Gvhd ◽

Risk Profile ◽

P Value ◽

Advisory Committees ◽

Donor Type

Abstract BACKGROUND. Allogeneic hematopoietic stem cell transplantation (HSCT) is of benefit in pediatric patients with high-risk acute lymphoblastic leukemia (ALL) in first or further remission. Whether transplantation from unrelated donors could yield similar results to transplantation from HLA identical siblings is still to be assessed within countries running different frontline and relapse protocols. AIM OF THE STUDY. A prospective study was initiated within the International BFM Study Group, in order to assess whether the outcome of HSCT from a 9 or 10 out of 10 HLA allelic matched compatible donor (MD) was inferior to the outcome of HSCT from a matched sibling donor (MSD) in children or young adults with ALL carrying very high risk eligibility criteria for transplantation. Primary endpoint was event-free survival (EFS) and secondary endpoints were non-relapse mortality (NRM) and incidence of acute and chronic graft-versus-host disease (aGVHD, cGVHD). PATIENTS AND METHODS. Between 2007 and 2013, 10 countries (Czech Republic, Denmark, France, Israel, Italy, The Netherlands, Poland, Sweden, Slovakia, Turkey) participated into the ALL SCT I-BFM Study, coordinated by Peters in Vienna. 298 consecutive patients, 18 years old or younger (70% male, median age 9 years), affected with VHR ALL in complete remission (CR), were enrolled in the core arm of the Study (MD vs MSD). Of 298, 107 patients were transplanted from a MSD (50% in CR1, 47% in CR2, 4% >CR2) and 191 from a MD (44% in CR1, 48% CR2, 9% >CR2), either related (5%) or unrelated (95%), at a median of 189 and 197 days, respectively, after diagnosis/relapse. As per protocol, conditioning regimen consisted of TBI-etoposide, in patients older than 2 years, or busulfan-cyclophosphamide-melphalan, in patients 2 years or younger, and GVHD-prophylaxis consisted of cyclosporine (CSA) only for MSD and CSA/methotrexate/ATG for MD recipients. Median follow-up for alive patients was 3.1 years. RESULTS. Three-year EFS was 67% (SE 5%) for MSD vs 61% (SE 4%) for MD recipients (p-value 0.254), overall survival (OS) 76% (SE 4%) vs 69% (SE 4%) (p-value 0.207), cumulative incidence of relapse (CIR) 24% (SE 4%) vs 22% (SE 3%) (p-value 0.935) and NRM 8% (SE 3%) vs 16% (SE 3%) (p-value 0.094), respectively. There was a trend for a higher risk NRM for MD patients, although no statistical significance was reached (HR 1.94, CI 0.85-4.41; p=0.114), after adjusting for risk profile and donor type. Being transplanted in CR2 was associated with lower EFS and higher NRM (p=0.001). Grade II-IV acute GVHD occurred in 37% and grade III-IV in 16% of MSD vs 42% and 15% of MD recipients; 39% of the evaluable MSD and 19% of the MD recipients experienced chronic GVHD, which was severe in 24% and 10%, respectively. Cumulative incidence of developing chronic GVHD was 39% (SE 5%) and 17% (SE 3%), for patients grafted from MSD and MD, respectively (p=0.001). Being transplanted from a MD, compared with a MSD, was significantly associated with a reduced risk of developing chronic GVHD (HR 0.31, CI 0.18-0.54, p <0.001), despite a similar risk of relapse (HR 0.81, CI 0.47-1.39; p=0.440). Acute GVHD grade 3 or 4 had statistically significant impact on NRM (HR 4.76, CI 2.33-9.74; <0.001) and OS (HR 1.97, CI 1.14-3.42; p=0.016), after adjusting for risk profile and donor type. CONCLUSIONS. Outcome of transplantation of MD pediatric recipients with VHR ALL in CR was not inferior to the outcome of MSD recipients in terms of EFS, OS, and CIR, with probability of chronic GVHD being lower for MD versus MSD recipients, which suggests the crucial role of serotherapy, and severe acute GVHD being associated with increased NRM and lower OS but similar CIR. Disclosures Dalle: Gilead: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Macopharma: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Peters:Medac: Research Funding; Fresenius: Research Funding; Amgen: Research Funding; Jazz: Research Funding; Novartis: Research Funding; Pfizer: Research Funding; Sanovi: Research Funding; Pierre-Fabre: Research Funding.

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Different Clinical Implications of Kinase Domain BCR-ABL1 Variants Detected in Chronic Myeloid Leukemia and Acute Lymphoblastic Leukemia Patients

Blood ◽

10.1182/blood-2019-127069 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 5368-5368

Author(s):

Ricardo Sanchez ◽

Rosa Ayala ◽

Gonzalo Carreño Gomez-Tarragona ◽

Espino Maria Jose ◽

Beatriz Cuevas ◽

...

Keyword(s):

Overall Survival ◽

Board Of Directors ◽

Myeloid Leukemia ◽

Research Funding ◽

Poor Prognosis ◽

Lymphoblastic Leukemia ◽

Kinase Domain ◽

Categorical Variables ◽

P Value ◽

Advisory Committees

Background: Kinase domain (KD) mutations is a common resistance mechanism, secondary to the tyrosine-kinase inhibitors (ITKs) treatment in the case of chronic myeloid leukemia (CML) and Philadelphia (Ph)-positive acute lymphoblastic leukemia (ALL) patients. Sanger sequencing is the gold standard technique and already the currently recommended method for BCR-ABL1 KD mutation detection. However, Sanger sequencing has limited sensitivity and cannot firmly identify populations with variant allele frequencies (VAF) < 15-20%. Next-generation sequencing (NGS) allow us the screening of mutations in the whole KD with variants with a VAF greater than 1%. The aim of this study is to evaluate the clinical and prognostic implications of CML and Ph-positive ALL patients who have been studied for mutations in BCR-ABL1 by NGS. Methods: Seventy CML and Ph-pos ALL patients have been studied for BCR-ABL1 mutations between years 2015-2017. The study reason was warning or failure according to European Leukemia Net recommendations in the case of CML patients, and diagnostic or relapse in the case of ALL patients. Clinical characteristics of the patients are depicted on Table 1. Categorical variables are described as frequency, and quantitative variables as medians. Contingency tables were used to analyze associations between categorical variables (χ2). Median test was used to compare medians of continuous variables between groups. Overall survival (OS) was estimated using the Kaplan-Meier method and compared between patients using the log-rank test. Results: We have found 37 patients with mutations (51%), the most frequent being p.T315I, p.L248V and p.L387M. 28 out of 59 were found in CML (47%) vs 9 out of 13 (69%) in ALL. Of the 37 patients with mutations, double mutations have been found 10 times (27%). In the 72 analyses performed, 62 mutations were found in total, 41 of them were variants of uncertain significance (VUS) and 21 were well-known mutation. The median levels of BCR-ABL1 (IS) at the time of analysis were 3.00 (0.01-196.18) %. Regarding CML patients, we have found 12 and 16 cases with pathogenic mutations and VUS, respectively. The mean survival for CML and ALL were 75.2 months (CI 95%, 65.7-84.6) and 24.7 months (13.3-36.2), respectively. There are significant differences between the overall survival curves for patients with CML who have mutations in BCR-ABL1 compared to those who have VUS or do not (p-value = 0.024, n=59), suggesting a second role of the VUS variants in the resistance of the patients to the TKI. These two groups have no significant differences in ALL patients (p-value= 0.32, n=13). Overall survival at 10 years from the date of diagnosis is 74% for CML patients with mutations and 90% for CML patients without mutations. Data dropped significantly for ALL patients, but the number of cases is too low. Conclusions: - Mutations have been identified in 47% of CML patients studied in the case of failure or warning and 69% of the patients of ALL at diagnosis or relapse moments. - The identification of pathogenic variants has poor prognosis in patients with CML (p = 0.024), however no differences were observed in ALL. - The identification of VUS is not associated to poor prognosis and these variants could not confer resistance to ITK. Disclosures Sevilla: Rocket Pharmaceuticals, Inc.: Honoraria, Patents & Royalties: Inventor on patents on lentiviral vectors filled by CIEMAT, CIBERER and F.J.D and may be entitled to receive financial benefits from the licensing of such patents; NOVARTIS: Honoraria, Membership on an entity's Board of Directors or advisory committees; Rocket: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sobi: Membership on an entity's Board of Directors or advisory committees; Miltenyi Biotech: Honoraria. Steegmann:Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. García Gutiérrez:Novartis: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Incyte: Honoraria, Research Funding.

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Therapeutic Targeting of Mertk and BCL-2 in T-Cell and Early T-Precursor Acute Lymphoblastic Leukemia

Blood ◽

10.1182/blood-2021-151726 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 1184-1184

Author(s):

Ryan J Summers ◽

Juhi Jain ◽

Eleana Vasileiadi ◽

Brittany Smith ◽

Madison Stout ◽

...

Keyword(s):

T Cell ◽

Board Of Directors ◽

Research Funding ◽

Lymphoblastic Leukemia ◽

Xenograft Model ◽

Prolonged Survival ◽

Cell Phenotype ◽

Advisory Committees ◽

Equity Ownership

Abstract Introduction T-cell acute lymphoblastic leukemia (T-ALL) accounts for 15% of childhood ALL and is associated with inferior outcomes relative to B-cell ALL. Early T-precursor ALL (ETP-ALL) is a subset of T-ALL characterized by an immature T cell phenotype, resistance to therapy, and high rates of induction failure. MERTK receptor tyrosine kinase is ectopically expressed in 40-50% of T-ALLs, particularly those with an immature T cell phenotype, suggesting a role in ETP-ALL. Inhibition of MERTK using shRNA delayed leukemia progression and prolonged survival in a T-ALL xenograft model, implicating MERTK as a therapeutic target. MRX-2843 is an orally available dual MERTK/FLT3 inhibitor currently in phase I clinical trials. The anti-apoptotic protein B-cell lymphoma-2 (BCL-2) is specifically expressed in immature T cell precursors, is preferentially expressed in ETP-ALL compared to other T-ALLs, is essential for ETP-ALL cell survival, and is regulated downstream of MERTK in acute leukemia cells. Thus, combination therapies targeting these two proteins may be particularly effective to treat ETP-ALL. Methods Loucy and PEER ETP-ALL cell lines were cultured with vehicle or MRX-2843. Phosphorylated and total MERTK were assessed by immunoblot. Relative cell numbers were measured using Presto Blue reagent. Cells were stained with PoPro-1-iodide and propidium iodide and apoptotic and dead cells were quantitated by flow cytometry. T-ALL patient samples were cultured with UNC2025, a close analogue of MRX-2843, and relative cell numbers were assessed using MTS reagent. Orthotopic xenografts were established in NSG or NSGS mice using luciferase-expressing Jurkat cells (T-ALL), luciferase-expressing Loucy cells (ETP-ALL) or an ETP-ALL patient sample and leukemia burden was monitored by bioluminescence imaging or flow cytometry. MRX-2843 (65 mg/kg or 75 mg/kg) or saline vehicle were administered orally once daily. Differences in disease burden were assessed with the Mann-Whitney-U test or one-way ANOVA. Survival was determined by Kaplan-Meier analysis. Loucy and PEER cells were plated and screened in quadruplicate against >150 pairwise combinations of MRX-2843 and the BCL-2 inhibitor venetoclax in a high-throughput format. Synergy was calculated using the response additivity model. Results Treatment with MRX-2843 mediated a dose-dependent decrease in phosphorylated MERTK, inhibited expansion of ETP-ALL cells, and induced cell death in vitro. Fifty-four percent (21/39) of primary T-ALL patient samples were sensitive to UNC2025 with an IC 50≤550 nM, including 2/5 (40%) pediatric samples and 10/19 (53%) adolescent/young adult samples. Treatment with MRX-2843 significantly reduced leukemia burden in cell line-derived T-ALL and ETP-ALL xenograft models and prolonged survival by 50% and 13% in the T-ALL (n=10, p<0.0001) and ETP-ALL (n=10, p=0.0136) models, respectively. Similarly, in a patient-derived ETP-ALL xenograft model, treatment with MRX-2843 reduced peripheral blood disease burden by 83% and spleen weight by 64% compared to vehicle-treated mice (n=8, p<0.001) and prolonged survival by 41% (n=8, p=0.0016). MRX-2843 mediated anti-leukemia activity in combination with venetoclax and a dose ratio of 1:20 MRX-2843:venetoclax provided optimal synergy in Loucy and PEER ETP-ALL cells in vitro (Figure 1). Conclusions MRX-2843 has therapeutic activity in ETP-ALL cell culture and xenograft models and over half of T-ALL patient samples were sensitive to MERTK/FLT3 inhibition. MRX-2843 also mediated synergistic anti-leukemia activity against ETP-ALL cells in combination with venetoclax, with an optimal molar ratio of 1:20. These data demonstrate the therapeutic potential of MRX-2843 in patients with T-ALL, suggest that MRX-2843 may be particularly active alone and in combination with venetoclax in the ETP-ALL subset, and provide rationale for clinical testing of MRX-2843, with the ultimate goal to progress to trials evaluating MRX-2843 in combination with other agents. Toward this end, MRX-2843 monotherapy will be tested in patients with relapsed leukemia in an upcoming clinical trial (NCT04872478). Figure 1 Figure 1. Disclosures Wang: Meryx: Other: Equity ownership; University of North Carolina: Patents & Royalties. Frye: University of North Carolina: Patents & Royalties; Meryx: Membership on an entity's Board of Directors or advisory committees, Other: Equity ownership. Earp: Meryx: Membership on an entity's Board of Directors or advisory committees, Other: Equity ownership. Tyner: Petra: Research Funding; Incyte: Research Funding; Takeda: Research Funding; Janssen: Research Funding; Astrazeneca: Research Funding; Array: Research Funding; Constellation: Research Funding; Seattle Genetics: Research Funding; Schrodinger: Research Funding; Genentech: Research Funding; Gilead: Research Funding; Agios: Research Funding. DeRyckere: Meryx: Other: Equity ownership. Graham: Meryx: Membership on an entity's Board of Directors or advisory committees, Other: Equity ownership.

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Blinatumomab Is Well Tolerated Maintenance Therapy Following Allogeneic Hematopoietic Cell Transplantation for Acute Lymphoblastic Leukemia

Blood ◽

10.1182/blood-2019-125931 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1298-1298 ◽

Cited By ~ 4

Author(s):

Partow Kebriaei ◽

Pinaki P Banerjee ◽

Christina Ganesh ◽

Mecit Kaplan ◽

Vandana Nandivada ◽

...

Keyword(s):

Acute Lymphoblastic Leukemia ◽

T Cell ◽

High Risk ◽

Board Of Directors ◽

Research Funding ◽

Hematopoietic Cell Transplantation ◽

Checkpoint Inhibitors ◽

Lymphoblastic Leukemia ◽

Advisory Committees ◽

Active Disease

Background: Patients with high-risk or multiply relapsed B-lineage acute lymphoblastic leukemia (ALL) have a very high rate of relapse, even after allogeneic hematopoietic cell transplantation (HCT). In an effort to reduce the risk for relapse, we investigated the role of blinatumomab (Blin), a bi-specific T cell immunotherapy targeting CD19, as maintenance therapy following allogeneic HCT for adult patients with advanced B ALL. We rationalized that this is an ideal agent with little cytotoxicity, and the potential to provide immune protection against disease relapse during the first year post HCT when graft versus leukemia (GVL) is still maturing. Methods: Adult patients with B-ALL deemed high risk for relapse defined as disease stage beyond CR1, any active disease including MRD, or presence of high risk molecular mutations or karyotype at time of HCT, or patients with evidence of MRD immediately following HCT, were eligible for study enrollment; prior Blin treatment was allowed. Patients with active disease defined as >5% malignant blasts or active GVHD requiring steroid therapy post HCT were excluded. Patients were scheduled to receive 4 cycles of Blin as a continuous intravenous infusion at the dose of 28 microgram/24 hours over 4 weeks, with the first cycle to be administered within the first 3 months post HCT after count recovery; the subsequent cycles were administered at 6, 9, and 12 months following HCT (day of hematopoietic progenitor cell infusion). Dose escalation for cycle 1 and hospitalization for observation during cycles 1 and 2 followed standard FDA issued guidelines. Results: 14 patients enrolled to date with 12 patients treated with median age 30 years (range, 21-65 years); two patients did not proceed with treatment due to graft versus host disease (GVHD). Patient characteristics and outcomes are listed in Table 1. The median days to start of therapy post HCT was 84 (range, 38-105 days). The treatment was well tolerated with no reported cytokine release syndrome, GVHD, graft failure, or grade 5 adverse events (AE). A cumulative 26 cycles of Blin were administered with 7 Blin-related grade 3 or 4 AEs reported (leukopenia n=4, transaminitis n=2, rash n=1). Grade 2 neurotoxicity manifesting as confusion and dysphagia requiring temporary suspension of therapy and short course steroids noted in 1 patient. Median follow up was 8.5 months post HCT (range 2-35 months). All 4 patients who were MRD positive prior to start of Blin have progressed and 2 have died. None of the 8 patients who were MRD negative post transplant has relapsed. We performed multiparametric flow cytometry studies on serial peripheral blood patient samples collected prospectively at multiple time points to measure T cell subsets, T-cell function and cell surface expression of various checkpoint inhibitors including PD1, TIGIT, Tim3, 2B4 and CD160. Samples were studied on an X-20 Fortessa, and the data analyzed using Kaluza software. Interestingly, the 4 patients who progressed on Blin maintenance had lower CD8 to CD4 ratio compared to non-progressors (17:60 vs. 46:42) (Figure 1). Furthermore, compared to healthy controls, we observed higher levels of checkpoint molecules as multiple checkpoints per cell. PD1 and TIGIT upregulation and co-expression were more common in progressing patients compared to non-progressors (Figure 2). Conclusion: We observed that Blin maintenance following allogeneic HCT for B ALL is well tolerated. More patients need to be treated to confirm the efficacy of this approach. This approach is encouraging for high risk ALL patients who are MRD negative post transplant. Strategies to increase CD8 levels and blockade against checkpoint inhibitors may overcome resistance to therapy. Disclosures Kebriaei: Amgen: Research Funding; Jazz: Consultancy; Pfizer: Honoraria; Kite: Honoraria. Ravandi:Xencor: Consultancy, Research Funding; Selvita: Research Funding; Macrogenix: Consultancy, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Menarini Ricerche: Research Funding; Cyclacel LTD: Research Funding. Jabbour:Adaptive: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Cyclacel LTD: Research Funding; Pfizer: Consultancy, Research Funding. Kantarjian:AbbVie: Honoraria, Research Funding; Novartis: Research Funding; Jazz Pharma: Research Funding; Agios: Honoraria, Research Funding; Cyclacel: Research Funding; Daiichi-Sankyo: Research Funding; Pfizer: Honoraria, Research Funding; Takeda: Honoraria; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding; Immunogen: Research Funding; Amgen: Honoraria, Research Funding; Astex: Research Funding; Ariad: Research Funding. Champlin:Sanofi-Genzyme: Research Funding; Johnson and Johnson: Consultancy; Actinium: Consultancy.

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