Remarkable Functional Constraints on the Antigen Receptors of CLL Stereotyped Subset #2: High-Throughput Immunogenetic Evidence

Abstract Subset #2 is the largest subset carrying stereotyped B cell receptor immunoglobulin (BcR IG) in chronic lymphocytic leukemia (CLL). This particular BcR IG is composed of heavy (HC) and light (LC) chains encoded by the IGHV3-21 and the lambda IGLV3-21 gene, respectively. The clonotypic IGHV3-21 genes display a variable load of somatic hypermutation (SHM), being mostly classified as mutated (M-CLL) but also including unmutated (U-CLL) cases. Subset #2 cases, independently of the SHM status, have a particularly dismal clinical outcome similar to that of patients with TP53 aberrations, although lacking such aberrations. Subset #2 BcR IG display a series of distinctive features, including conservation at certain VH and VL CDR3 positions and recurrent SHMs; as well as a capacity for self-association leading to cell autonomous signaling that is critically dependent on a substitution of Arginine (R) for Glycine (G) introduced by SHM at the lambda VL-CL linker region. These features implicate antigen selection in CLL subset #2 ontogeny. However, the available molecular evidence derives from low throughput immunogenetic analysis, precluding comprehensive assessment of antigenic impact on (sub)clonal composition. Here, we sought to overcome this limitation by performing next-generation sequencing (NGS) of HC and LC gene rearrangements of 20 subset #2 patients. RT-PCR products amplified by the IGHV3-21/IGHJ6 and IGLV3-21/IGLC primer pairs, respectively, were subjected to NGS on the MiSeq Illumina Platform. NGS data was analyzed by a validated bioinformatics pipeline. Rearrangements with identical CDR3 amino acid (aa) sequences were defined as clonotypes, whereas clonotypes with different aa substitutions within the V-domain were defined as subclones. Starting with HCs, we obtained 3,340,508 (mean: 291,751, range: 101,231-186,055) productive reads. On average, each analyzed sample carried 92 distinct clonotypes (range: 71-152), with the dominant clonotype having a mean frequency of 96% (range: 67-99%): in all cases the dominant clonotype was identical to that determined by Sanger sequencing. The dominant clonotype displayed considerable intraclonal heterogeneity with a mean of 5,082 subclones/sample (range: 2,946-11,041). Turning to LCs, we obtained 5,094,045 (mean: 231,547, range: 38,036-507,949) productive reads. LCs carried a higher number of distinct clonotypes/sample compared to their partner HCs (mean 222, range: 156-306). The dominant clonotype had a mean frequency of 96% (range: 74-98%); similar to HCs, it was identical to that determined by Sanger sequencing. Intraclonal heterogeneity was observed in the LCs as well, with a mean of 7,382 subclones/sample (range: 1,946-11,866), hence more pronounced vs their partner HCs. Viewing the entire subset #2 VH or VL CDR3 dataset (i.e. the CDR3 aa sequences from all clonotypes of all cases) as a single entity branching through diversification enabled the identification of 2 distinct VH CDR3 sequences present at varying frequencies in 16 and 13 cases, respectively; and, 3 distinct VL CDR3 sequences present at varying frequencies in all 20 cases: these results allude to important constraints on the composition of the antigen binding site. Focusing on SHM, the following notable observations could be made. (i) The G-to-R substitution at the VL-CL linker was a clonal event in all cases with R being degenerately encoded by different nucleotide sequences; altogether, these findings underscore the seminal role of this recurrent SHM, likely due to mediating self-association. (ii) A recurrent 3-nucleotide deletion was detected in the VH CDR2 of all cases, strongly supporting functional pressure. This change, previously identified by Sanger sequencing as a recurrent SHM in subset #2 (albeit at a frequency of only 25%), was clonal in 4 cases and subclonal in the remainder, where it was present in an average of 105 subclones/sample (range: 1-369). (iii) Certain positions in both the VH and VL domain bore the same aa substitution, mostly at subclonal level: the prime example concerned the G for Serine (S) substitution within the VL CDR3, detected in all samples at a mean frequency of 44.2% (range: 6.3-87%). In conclusion, we provide compelling immunogenetic evidence for functional pressure in the ontogeny of CLL subset #2. On this evidence, subset #2 emerges as perhaps the most striking example of antigen-driven leukemogenesis reported thus far. Disclosures Gemenetzi: Gilead: Research Funding. Agathangelidis:Gilead: Research Funding. Stamatopoulos:Abbvie: Honoraria, Research Funding; Gilead: Honoraria, Research Funding; Janssen: Honoraria, Research Funding. Hadzidimitriou:Abbvie: Research Funding; Gilead: Research Funding; Janssen: Honoraria, Research Funding.

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Higher Order Restrictions of the Immunoglobulin Repertoire in CLL: The Illustrative Case of Stereotyped Subsets #2 and #169

Blood ◽

10.1182/blood-2019-128017 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 5453-5453

Author(s):

Katerina Gemenetzi ◽

Andreas Agathangelidis ◽

Fotis Psomopoulos ◽

Karla Plevova ◽

Lesley-Ann Sutton ◽

...

Keyword(s):

Research Funding ◽

High Throughput Sequencing ◽

Somatic Hypermutation ◽

Illustrative Case ◽

Gene Rearrangements ◽

Sequencing Data ◽

Bioinformatics Pipeline ◽

Mean Frequency ◽

Cdr3 Sequence ◽

Sample Range

Stereotyped subset #2 (IGHV3-21/IGLV3-21) is the largest subset in CLL (~3% of all patients). Membership in subset #2 is clinically relevant since these patients experience an aggressive disease irrespective of the somatic hypermutation (SHM) status of the clonotypic immunoglobulin heavy variable (IGHV) gene. Low-throughput evidence suggests that stereotyped subset #169, a minor CLL subset (~0.2% of all CLL), resembles subset #2 at the immunogenetic level. More specifically: (i) the clonotypic heavy chain (HC) of subset #169 is encoded by the IGHV3-48 gene which is closely related to the IGHV3-21 gene; (ii) both subsets carry VH CDR3s comprising 9-amino acids (aa) with a conserved aspartic acid (D) at VH CDR3 position 3; (iii) both subsets bear light chains (LC) encoded by the IGLV3-21 gene with a restricted VL CDR3; and, (iv) both subsets have borderline SHM status. Here we comprehensively assessed the ontogenetic relationship between CLL subsets #2 and #169 by analyzing their immunogenetic signatures. Utilizing next-generation sequencing (NGS) we studied the HC and LC gene rearrangements of 6 subset #169 patients and 20 subset #2 cases. In brief, IGHV-IGHD-IGHJ and IGLV-IGLJ gene rearrangements were RT-PCR amplified using subgroup-specific leader primers as well as IGHJ and IGLC primers, respectively. Libraries were sequenced on the MiSeq Illumina instrument. IG sequence annotation was performed with IMGT/HighV-QUEST and metadata analysis conducted using an in-house, validated bioinformatics pipeline. Rearrangements with identical CDR3 aa sequences were herein defined as clonotypes, whereas clonotypes with different aa substitutions within the V-domain were defined as subclones. For the HC analysis of subset #169, we obtained 894,849 productive sequences (mean: 127,836, range: 87,509-208,019). On average, each analyzed sample carried 54 clonotypes (range: 44-68); the dominant clonotype had a mean frequency of 99.1% (range: 98.8-99.2%) and displayed considerable intraclonal heterogeneity with a mean of 2,641 subclones/sample (range: 1,566-6,533). For the LCs of subset #169, we obtained 2,096,728 productive sequences (mean: 299,533, range: 186,637-389,258). LCs carried a higher number of distinct clonotypes/sample compared to their partner HCs (mean: 148, range: 110-205); the dominant clonotype had a mean frequency of 98.1% (range: 97.2-98.6%). Intraclonal heterogeneity was also observed in the LCs, with a mean of 6,325 subclones/sample (range: 4,651-11,444), hence more pronounced than in their partner HCs. Viewing each of the cumulative VH and VL CDR3 sequence datasets as a single entity branching through diversification enabled the identification of common sequences. In particular, 2 VH clonotypes were present in 3/6 cases, while a single VL clonotype was present in all 6 cases, albeit at varying frequencies; interestingly, this VL CDR3 sequence was also detected in all subset #2 cases, underscoring the molecular similarities between the two subsets. Focusing on SHM, the following observations were made: (i) the frequent 3-nucleotide (AGT) deletion evidenced in the VH CDR2 of subset #2 (leading to the deletion of one of 5 consecutive serine residues) was also detected in all subset #169 cases at subclonal level (average: 6% per sample, range: 0.1-10.8%); of note, the 5-serine stretch is also present in the germline VH CDR2 of the IGHV3-48 gene; (ii) the R-to-G substitution at the VL-CL linker, a ubiquitous SHM in subset #2 and previously reported as critical for IG self-association leading to cell autonomous signaling in this subset, was present in all subset #169 samples as a clonal event with a mean frequency of 98.3%; and, finally, (iii) the S-to-G substitution at position 6 of the VL CDR3, present in all subset #2 cases (mean : 44.2% ,range: 6.3-87%), was also found in all #169 samples, representing a clonal event in 1 case (97.2% of all clonotypes) and a subclonal event in the remaining 5 cases (mean: 0.6%, range: 0.4-1.1%). In conclusion, the present high-throughput sequencing data cements the immunogenetic relatedness of CLL stereotyped subsets #2 and #169, further highlighting the role of antigen selection throughout their natural history. These findings also argue for a similar pathophysiology for these subsets that could also be reflected in a similar clonal behavior, with implications for risk stratification. Disclosures Sutton: Abbvie: Honoraria; Gilead: Honoraria; Janssen: Honoraria. Stamatopoulos:Abbvie: Honoraria, Research Funding; Janssen: Honoraria, Research Funding. Chatzidimitriou:Janssen: Honoraria.

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EGR2 Mutations in Chronic Lymphocytic Leukemia: A New Bad Player

Blood ◽

10.1182/blood.v126.23.4126.4126 ◽

2015 ◽

Vol 126 (23) ◽

pp. 4126-4126

Author(s):

Daniel Noerenberg* ◽

Emma Young* ◽

Viktor Ljungström ◽

Larry Mansouri ◽

Karla Plevova ◽

...

Keyword(s):

Overall Survival ◽

General Practice ◽

Chronic Lymphocytic Leukemia ◽

Deep Sequencing ◽

Research Funding ◽

Sanger Sequencing ◽

Lymphocytic Leukemia ◽

Prognostic Impact ◽

Bcr Signaling ◽

The Uk

Abstract *Contributed equally as first authors. **Contributed equally as senior authors. Recurrent mutations within EGR2, a versatile transcription factor involved in differentiation of hematopoietic cells, were recently reported in 8% of advanced-stage chronic lymphocytic leukemia (CLL) patients, where they appear to be associated with a worse outcome. EGR2 is activated through ERK phosphorylation upon B-cell receptor (BcR) stimulation, and we have previously shown that EGR2 -mutated CLL patients display altered expression of EGR2 down-stream target genes compared to wildtype (wt) patients, thereby pointing to a pathogenic role for EGR2 mutations in dysregulating BcR signaling. To gain further insight into the incidence and prognostic impact of EGR2 mutations in CLL, we screened samples from a well-characterized series of 1430 patients, either by Sanger sequencing (n=1019) or targeted deep-sequencing (n=370), both covering the recently reported EGR2 hotspot in exon 2. In addition, whole-exome data was available for an additional 43 patients. Different cohorts were included in our analysis ranging from 'general practice' CLL (33% IGHV-unmutated (U-CLL), 6% TP53 -aberrant (TP53abn), n=693), to adverse-prognostic CLL (89% U-CLL, 26% TP53abn, n=325), patients belonging to clinically aggressive stereotyped subsets #1-3 & #5-8 (n=342), patients relapsing after FCR therapy (n=41) and Richter transformed cases (n=31), thus reflecting the heterogeneous nature of CLL. Nineteen EGR2 mutations were detected by Sanger sequencing, while 22 additional mutations were identified with deep-sequencing using a 5% variant allele frequency (VAF) cutoff (median 39%, range 5.6-63.9%, median coverage 43,000X). With the exception of one in-frame deletion, all mutations were missense alterations located within the three zinc-finger domains. Significant enrichment of EGR2 mutations was observed in adverse-prognostic (18/325, 5.5%) and FCR-relapsing (4/41, 9.8%) CLL compared to the 'general practice' cohort (18/693, 2.6%, Figure 1A). A surprisingly low frequency was observed among clinically aggressive stereotyped subsets (5/342, 1.5%), although the cause for this observation is currently unknown. Finally, 2/31 (6.5%) cases with Richter transformation carried an EGR2 mutation. Of the 4 FCR-relapsing, EGR2 -mutated cases with available overtime samples, all demonstrated a significant expansion of the EGR2 -mutated clone at relapse (VAF-increase between 15-41%). In addition, subclonal levels of EGR2 hotspot mutations (VAF 0.5-5%) were detected in an additional 13/370 (3.5%) cases by deep-sequencing. The majority of EGR2 -mutated CLL patients (32/39, 82%) concerned U-CLL and the following aberrations co-occurred: 11q-deletions (n=10), TP53abn (n=6), NOTCH1 (n=3)or SF3B1 (n=3) mutations. EGR2 -mutated patients displayed a significantly worse overall survival compared to wt patients (median survival 59 vs. 141 months, p=0.003, using a conservative 10% VAF cutoff), and a poor outcome similar to cases with TP53abn (Figure 1B). In multivariate analysis (n=583), EGR2 status remained an independent factor (p=0.038), along with stage (p=0.048) and IGHV status (p<0.0001), while TP53abn and del(11q) showed borderline significant values (p=0.069 and p=0.059, respectively). To investigate the impact of EGR2 mutations in a homogeneously treated patient cohort, EGR2 mutation analysis of the UK CLL4 trial is underway. To date, 8/247 patients have been identified as EGR2 -mutated by deep-sequencing and they show a decrease of their median overall survival (42 vs. 77 months) compared to wt patients; however, this did not reach statistical significance, probably due to the low number of EGR2 -mutated cases. Final results of the UK CLL4 trial will be presented at the ASH meeting. In summary, EGR2 -mutant cases appear to constitute a novel poor-prognostic subgroup of CLL, with mutations occurring either as disease-initiating aberrations, i.e. in cases where mutations were found in the entire clone, or as subclonal driver events linked to progressive disease. The latter is reflected by the enrichment of EGR2 mutations in aggressive CLL and the association of EGR2 mutations with an overall dismal prognosis. Considering the potential role of mutated EGR2 in altering BcR signaling, it will be particularly relevant to study the efficacy of BcR inhibitors in this patient group. Figure 1. Figure 1. Figure 2. Figure 2. Disclosures Langerak: Roche: Other: Lab services in the field of MRD diagnostics provided by Dept of Immunology, Erasmus MC (Rotterdam); InVivoScribe: Patents & Royalties: Licensing of IP and Patent on BIOMED-2-based methods for PCR-based Clonality Diagnostics.; DAKO: Patents & Royalties: Licensing of IP and Patent on Split-Signal FISH. Royalties for Dept. of Immunology, Erasmus MC, Rotterdam, NL. Schuh:Acerta Pharma BV: Research Funding. Strefford:Roche: Research Funding.

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VH CDR3-Focused Somatic Hypermutation in CLL IGHV-IGHD-IGHJ Gene Rearrangements with 100% IGHV Germline Identity

Blood ◽

10.1182/blood-2019-127979 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 4277-4277 ◽

Cited By ~ 1

Author(s):

Katerina Gemenetzi ◽

Andreas Agathangelidis ◽

Fotis Psomopoulos ◽

Kostas Pasentsis ◽

Evdoxia Koravou ◽

...

Keyword(s):

Research Funding ◽

Somatic Hypermutation ◽

Lymphocytic Leukemia ◽

Gene Rearrangements ◽

Rt Pcr ◽

Bioinformatics Pipeline ◽

Sample Mean ◽

Mean Frequency ◽

High Data ◽

Ighv Gene

Classification of patients with chronic lymphocytic leukemia (CLL) based on the immunoglobulin heavy variable (IGHV) gene somatic hypermutation (SHM) status has established predictive and prognostic relevance. The SHM status is assessed based on the number of mutations within the sequence of the rearranged IGHV gene excluding the VH CDR3. This is mostly due to the difficulty in discriminating actual SHM from random nucleotides added between the recombined IGHV, IGHD and IGHJ genes. Hence, this approach may underestimate the true impact of SHM, in fact overlooking the most critical region for antigen-antibody interactions i.e. the VH CDR3. Relevant to mention in this respect, studies from our group in CLL with mutated IGHV genes (M-CLL), particularly subset #4, have revealed considerable intra-VH CDR3 diversity attributed to ongoing SHM. Prompted by these findings, here we investigated whether SHM may also be present in cases bearing 'truly unmutated' IGHV genes (i.e. 100% germline identity across VH FR1-VH FR3), focusing on two well characterized stereotyped subsets i.e. subset #1 (IGHV clan I/IGHD6-19/IGHJ4) and subset #6 (IGHV1-69/IGHD3-16/IGHJ3). These subsets carry germline-encoded amino acid (aa) motifs within the VH CDR3, namely QWL and YDYVWGSY, originating from the IGHD6-19 and IGHD3-16 gene, respectively. However, in both subsets, cases exist with variations in these motifs that could potentially represent SHM. The present study included 12 subset #1 and 5 subset #6 patients with clonotypic IGHV genes lacking any SHM (100% germline identity). IGHV-IGHD-IGHJ gene rearrangements were RT-PCR amplified by subgroup-specific leader primers and a high-fidelity polymerase in order to ensure high data quality. RT-PCR products were subjected to paired-end NGS on the MiSeq platform. Sequence annotation was performed with IMGT/HighV-QUEST and metadata analysis was undertaken using an in-house purpose-built bioinformatics pipeline. Rearrangements with the same IGHV gene and identical VH CDR3 aa sequences were defined as clonotypes. Overall, we obtained 1,570,668 productive reads with V-region identity 99-100%; of these, 1,232,958 (mean: 102,746, range: 20,796-242,519) concerned subset #1 while 337,710 (mean: 67,542, range: 50,403-79,683) concerned subset #6. On average, 64.4% (range: 1.7-77.5%) of subset #1 reads and 49.2% (range: 0.7-70%) of subset #6 reads corresponded to rearrangements with IGHV genes lacking any SHM (100% germline identity). Clonotype computation revealed 1,831 and 1,048 unique clonotypes for subset #1 and #6, respectively. Subset #1 displayed a mean of 157 distinct clonotypes per sample (range: 74-267), with the dominant clonotype having a mean frequency of 96.9% (range: 96-98.2%). Of note, 44 clonotypes were shared between different patients (albeit at varying frequencies), including the dominant clonotype of 11/12 cases, which was present in 2-6 additional subset #1 patients. Subset #6 cases carried a higher number of distinct clonotypes per sample (mean: 219, range: 189-243) while the dominant clonotype had a mean frequency of 95.6% (range: 94.5-96.5%). Shared clonotypes (n=30) were identified also in subset #6 and the dominant clonotype of each subset #6 case was present in 3-5 additional subset #6 patients. Focusing on the VH CDR3, in particular the IGHD-encoded part, the following observations were made: (1) in both subsets, extensive intra-VH CDR3 variation was detected at certain positions within the IGHD gene; (2) in most cases, the observed aa substitutions were conservative i.e. concerned aa sharing similar physicochemical properties. Particularly noteworthy in this respect were the observations in subset #6 that: (i) the valine residue (V) in the D-derived YDYVWGSY motif was very frequently mutated to another aliphatic residue (A, I, L); (ii) in cases were the predominant clonotype carried I (also in the Sanger-derived sequence), several minor clonotypes carried the germline-encoded V, compelling evidence that the observed substitution concerned true SHM. In conclusion, we provide immunogenetic evidence for intra-VH CDR3 variations, very likely attributed to SHM, in CLL patients carrying 'truly unmutated' IGHV genes. While the prognostic/predictive relevance of this observation is beyond the scope of the present work, our findings highlight the possible need to reappraise definitions ('semantics') regarding SHM status in CLL. Disclosures Stamatopoulos: Janssen: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding. Chatzidimitriou:Janssen: Honoraria.

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Gene Mutations and Treatment Outcome in Chronic Lymphocytic Leukemia: Results From the CLL8 Trial

Blood ◽

10.1182/blood.v120.21.433.433 ◽

2012 ◽

Vol 120 (21) ◽

pp. 433-433 ◽

Cited By ~ 3

Author(s):

Stephan Stilgenbauer ◽

Raymonde Busch ◽

Andrea Schnaiter ◽

Peter Paschka ◽

Marianna Rossi ◽

...

Keyword(s):

Prognostic Factors ◽

Research Funding ◽

Sanger Sequencing ◽

Cox Regression ◽

Specific Treatment ◽

Gene Mutations ◽

Response To Therapy ◽

Lymphocytic Leukemia ◽

Prognostic Impact ◽

Multivariable Analyses

Abstract Abstract 433 Novel gene mutations have been found in CLL by next generation sequencing including mutations of NOTCH1 and SF3B1 in 5–20% of cases. In initial studies, both have been associated with advanced disease and poor outcome. We assessed the incidence and impact of gene mutations in the CLL8 trial (1st line FC vs. FCR, n=817). TP53 (exons 2–11) was analyzed by a re-sequencing chip (Amplichip, Roche Molecular Systems) with confirmatory Sanger sequencing. NOTCH1 was analyzed by Sanger sequencing exon 34, chr9:139,390,619–139,391,290 (PEST domain). SF3B1 (exons 13–16) was analyzed by DHPLC (WAVE® 3500HT, Transgenomic Inc.) with subsequent Sanger sequencing. Baseline samples were available for analysis of genetic markers in 619 (75.8%) to 645 (78.9%) patients. All markers were available for 573 (70.1%) patients and this cohort was representative of the full trial population. Mutations (mut) were found in TP53, NOTCH1, and SF3B1 in 11.5%, 10.0%, and 18.4%, respectively. At least one mutation was identified in 35.2% patients, while 30.6% had one, 4.4% had two and 0.2% had three mutations. Concurrent NOTCH1mut and SF3B1mut were found in only 0.5% patients. TP53mut was observed in 16.7% of NOTCH1mut cases (p=.528) and in 14.5% of SF3B1mut patients (p=.472). Regarding baseline characteristics, there were significant associations of TP53mut with CIRS>1, unmutated IGHV and 17p-; of NOTCH1mut with Binet A/B, no B-symptoms, unmutated IGHV, and 17p-; and of SF3B1mut with TK>10, and no +12. Regarding response to therapy, TP53mut was significantly associated with refractory disease in both arms (FCR: 25.0% vs. 1.8%, p<.001, FC: 48.4% vs. 7.8%, p<.001,); while NOTCH1mut showed only a trend in the FCR arm (FCR: 10.9% vs. 3.4%, p=.109, FC: 11.9% vs. 12.9%, p=.775); and SF3B1mut did not impact response to therapy (FCR: 3.6% vs. 3.7%, p=1.00, FC: 12.3% vs. 10.9%, p=1.00). At extended follow-up (median 69.97 months), FCR resulted into significantly improved PFS (HR 0.586, p<.001) and OS (HR 0.678, p=.001). TP53mut was associated in both treatment arms with significantly decreased PFS (FC: HR 4.295, p<.001; FCR: HR 3.173 p<.001) and OS (FC: HR 4.642 p<.001; FCR: HR 4.447, p<.001). In contrast, NOTCH1mut was only in the FCR arm associated with significantly decreased PFS (FC: HR 0.931, p=.741; FCR: HR 1.718, p=.013) and a trend to inferior OS (FC: HR 0.854, p=.605; FCR: HR 1.610, p=.112). SF3B1mut was associated in both treatment arms with significantly decreased PFS (FC: HR 1.520, p=.009; FCR: HR 1.463, p=.033) and a trend to inferior OS (FC: HR 1.338, p=.178; FCR: HR 1.305, p=.301). To evaluate the independent prognostic impact, we performed multivariable analyses by Cox regression for PFS and OS including the following variables: treatment, age, sex, stage, ECOG status, B-symptoms, WBC, TK, β2-MG, 11q-, +12, 13q-, 17p-, IGHV, TP53, NOTCH1 and SF3B1. Regarding PFS, the following independent prognostic factors were identified: FCR (HR 0.510, p<.001), TK>10 (HR 1.367, p=.019), IGHV<98% (HR 1.727, p<.001), 11q- (HR 1.536, p<.001), 17p- (HR 2.949 p<.001), TP53mut (HR 2.113 p<.001), and SF3B1mut (HR 1.348, p=.024). Regarding OS, the following independent prognostic factors were identified: FCR (HR 0.701, p=.049), ECOG>0 (HR 2.202, p<.001), TK>10 (HR 2.707, p<.001), IGHV<98% (HR 1.547, p=.055), 17p- (HR 3.546 p<.001) and TP53mut (HR 3.032 p<.001). To identify a predictive impact of gene mutations for a specific treatment effect by the addition of rituximab, we performed multivariable analyses including the treatment arms, the gene mutations and the interaction of both. Regarding PFS, FCR (HR 0.544, p<.001), TP53mut (HR 3.607, p<.001), SF3B1mut (HR 1.355, p=.012) and NOTCH1mut interaction with FCR (HR 1.652, p=.022) were identified as independent factors. Regarding OS, FCR (HR 0.654, p=.002) and TP53mut (HR 4.470, p<.001) were identified as independent factors while NOTCH1mut interaction with FCR (HR 1.331, p=.344) showed a trend. The interaction between NOTCH1mut and FCR treatment is illustrated in univariate PFS analysis, in which the addition of rituximab led to a benefit only among patients without NOTCH1mut (Figure). In conclusion, gene mutations show independent prognostic value for PFS (TP53, SF3B1) and OS (TP53) in patients receiving 1st line FC and FCR treatment. Of note, NOTCH1mut appears to identify a subset of CLL patients that does not benefit from the addition of rituximab to FC. Disclosures: Stilgenbauer: Roche: Consultancy, Honoraria, Research Funding. Patten:Roche: Employment. Wenger:Roche: Employment. Mendila:Roche: Employment. Hallek:Roche: Consultancy, Honoraria, Research Funding.

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Distinct Gene Expression Signatures in Patients with Richter's Syndrome and Chronic Lymphocytic Leukemia with Prior Exposure to Ibrutinib

Blood ◽

10.1182/blood-2020-136172 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 30-31

Author(s):

Hanyin Wang ◽

Shulan Tian ◽

Qing Zhao ◽

Wendy Blumenschein ◽

Jennifer H. Yearley ◽

...

Keyword(s):

Gene Expression ◽

B Cell ◽

Board Of Directors ◽

Research Funding ◽

Cell Activation ◽

Expression Profiles ◽

Lymphocytic Leukemia ◽

B Cell Activation ◽

Advisory Committees ◽

Upregulated Genes

Introduction: Richter's syndrome (RS) represents transformation of chronic lymphocytic leukemia (CLL) into a highly aggressive lymphoma with dismal prognosis. Transcriptomic alterations have been described in CLL but most studies focused on peripheral blood samples with minimal data on RS-involved tissue. Moreover, transcriptomic features of RS have not been well defined in the era of CLL novel therapies. In this study we investigated transcriptomic profiles of CLL/RS-involved nodal tissue using samples from a clinical trial cohort of refractory CLL and RS patients treated with Pembrolizumab (NCT02332980). Methods: Nodal samples from 9 RS and 4 CLL patients in MC1485 trial cohort were reviewed and classified as previously published (Ding et al, Blood 2017). All samples were collected prior to Pembrolizumab treatment. Targeted gene expression profiling of 789 immune-related genes were performed on FFPE nodal samples using Nanostring nCounter® Analysis System (NanoString Technologies, Seattle, WA). Differential expression analysis was performed using NanoStringDiff. Genes with 2 fold-change in expression with a false-discovery rate less than 5% were considered differentially expressed. Results: The details for the therapy history of this cohort were illustrated in Figure 1a. All patients exposed to prior ibrutinib before the tissue biopsy had developed clinical progression while receiving ibrutinib. Unsupervised hierarchical clustering using the 300 most variable genes in expression revealed two clusters: C1 and C2 (Figure 1b). C1 included 4 RS and 3 CLL treated with prior chemotherapy without prior ibrutinib, and 1 RS treated with prior ibrutinib. C2 included 1 CLL and 3 RS received prior ibrutinib, and 1 RS treated with chemotherapy. The segregation of gene expression profiles in samples was largely driven by recent exposure to ibrutinib. In C1 cluster (majority had no prior ibrutinb), RS and CLL samples were clearly separated into two subgroups (Figure 1b). In C2 cluster, CLL 8 treated with ibrutinib showed more similarity in gene expression to RS, than to other CLL samples treated with chemotherapy. In comparison of C2 to C1, we identified 71 differentially expressed genes, of which 34 genes were downregulated and 37 were upregulated in C2. Among the upregulated genes in C2 (majority had prior ibrutinib) are known immune modulating genes including LILRA6, FCGR3A, IL-10, CD163, CD14, IL-2RB (figure 1c). Downregulated genes in C2 are involved in B cell activation including CD40LG, CD22, CD79A, MS4A1 (CD20), and LTB, reflecting the expected biological effect of ibrutinib in reducing B cell activation. Among the 9 RS samples, we compared gene profiles between the two groups of RS with or without prior ibrutinib therapy. 38 downregulated genes and 10 upregulated genes were found in the 4 RS treated with ibrutinib in comparison with 5 RS treated with chemotherapy. The top upregulated genes in the ibrutinib-exposed group included PTHLH, S100A8, IGSF3, TERT, and PRKCB, while the downregulated genes in these samples included MS4A1, LTB and CD38 (figure 1d). In order to delineate the differences of RS vs CLL, we compared gene expression profiles between 5 RS samples and 3 CLL samples that were treated with only chemotherapy. RS samples showed significant upregulation of 129 genes and downregulation of 7 genes. Among the most significantly upregulated genes are multiple genes involved in monocyte and myeloid lineage regulation including TNFSF13, S100A9, FCN1, LGALS2, CD14, FCGR2A, SERPINA1, and LILRB3. Conclusion: Our study indicates that ibrutinib-resistant, RS-involved tissues are characterized by downregulation of genes in B cell activation, but with PRKCB and TERT upregulation. Furthermore, RS-involved nodal tissues display the increased expression of genes involved in myeloid/monocytic regulation in comparison with CLL-involved nodal tissues. These findings implicate that differential therapies for RS and CLL patients need to be adopted based on their prior therapy and gene expression signatures. Studies using large sample size will be needed to verify this hypothesis. Figure Disclosures Zhao: Merck: Current Employment. Blumenschein:Merck: Current Employment. Yearley:Merck: Current Employment. Wang:Novartis: Research Funding; Incyte: Research Funding; Innocare: Research Funding. Parikh:Verastem Oncology: Honoraria; GlaxoSmithKline: Honoraria; Pharmacyclics: Honoraria, Research Funding; MorphoSys: Research Funding; Ascentage Pharma: Research Funding; Genentech: Honoraria; AbbVie: Honoraria, Research Funding; Merck: Research Funding; TG Therapeutics: Research Funding; AstraZeneca: Honoraria, Research Funding; Janssen: Honoraria, Research Funding. Kenderian:Sunesis: Research Funding; MorphoSys: Research Funding; Humanigen: Consultancy, Patents & Royalties, Research Funding; Gilead: Research Funding; BMS: Research Funding; Tolero: Research Funding; Lentigen: Research Funding; Juno: Research Funding; Mettaforge: Patents & Royalties; Torque: Consultancy; Kite: Research Funding; Novartis: Patents & Royalties, Research Funding. Kay:Astra Zeneca: Membership on an entity's Board of Directors or advisory committees; Acerta Pharma: Research Funding; Juno Theraputics: Membership on an entity's Board of Directors or advisory committees; Dava Oncology: Membership on an entity's Board of Directors or advisory committees; Oncotracker: Membership on an entity's Board of Directors or advisory committees; Sunesis: Research Funding; MEI Pharma: Research Funding; Agios Pharma: Membership on an entity's Board of Directors or advisory committees; Bristol Meyer Squib: Membership on an entity's Board of Directors or advisory committees, Research Funding; Tolero Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Research Funding; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Rigel: Membership on an entity's Board of Directors or advisory committees; Morpho-sys: Membership on an entity's Board of Directors or advisory committees; Cytomx: Membership on an entity's Board of Directors or advisory committees. Braggio:DASA: Consultancy; Bayer: Other: Stock Owner; Acerta Pharma: Research Funding. Ding:DTRM: Research Funding; Astra Zeneca: Research Funding; Abbvie: Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; Octapharma: Membership on an entity's Board of Directors or advisory committees; MEI Pharma: Membership on an entity's Board of Directors or advisory committees; alexion: Membership on an entity's Board of Directors or advisory committees; Beigene: Membership on an entity's Board of Directors or advisory committees.

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

Blood ◽

10.1182/blood-2019-128871 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 2077-2077

Author(s):

Elizabeth M. Muhowski ◽

Amy M. Lehman ◽

Sean D. Reiff ◽

Janani Ravikrishnan ◽

Rose Mantel ◽

...

Keyword(s):

Research Funding ◽

Ohio State University ◽

Lymphocytic Leukemia ◽

State University ◽

Advisory Committees ◽

University Patents ◽

Kinase C ◽

Hla Dr ◽

Bcr Signaling ◽

Equity Ownership

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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Mechanisms of Adaptation to Ibrutinib in High Risk Chronic Lymphocytic Leukemia

Blood ◽

10.1182/blood-2018-99-116739 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 585-585 ◽

Cited By ~ 4

Author(s):

Valeria Spina ◽

Gabriela Forestieri ◽

Antonella Zucchetto ◽

Alessio Bruscaggin ◽

Tamara Bittolo ◽

...

Keyword(s):

High Risk ◽

Chronic Lymphocytic Leukemia ◽

Nuclear Localization ◽

Peripheral Blood ◽

Research Funding ◽

Clonal Evolution ◽

Lymphocytic Leukemia ◽

Adaptation Process ◽

Over Time ◽

Stimulation Of

Abstract Introduction. Ibrutinib inhibits the BTK molecule downstream the B-cell receptor (BCR). Though highly active in high risk chronic lymphocytic leukemia (CLL), the most typical response achievable in patients is a minimal residual disease (MRD) positive partial remission (PR) which is maintained until the development of genetically driven resistance caused by the acquisition of mutations in the BTK or PLCG2 genes. The study aims at characterizing the adaptation process allowing residual CLL cells to persist despite BTK inhibition. Methods. The IOSI-EMA-001 study (NCT02827617) is an observational study consisting in the prospective and longitudinal collection of peripheral blood samples and clinical data from high risk CLL patients treated with ibrutinib. Peripheral blood CLL cells longitudinally drawn from patients before treatment start and at fixed timepoints under ibrutinib were monitored by: i) next generation flow cytometry approaches for changes in proliferation rate, surfaceome, and pathway activation; and ii) CAPP-seq targeted deep next generation (sensitivity ~10-3) for clonal evolution. Results. The study cohort comprised 31 high risk CLL patients, including 15 treatment naïve, 16 relapsed, 80% IGHV unmutated, 42% 17p deleted and 55% TP53 mutated. Median duration of ibrutinib treatment was 45 weeks (24-72 weeks). All patients obtained a MRD positive PR that was maintained in all but one who progressed with a PLCG2 mutation (VAF 3%). Compared to baseline, under ibrutinib therapy CLL cells slowed down their proliferation, as suggested by the decreased expression of Ki-67, the reduction of the proliferating fraction (CXCR4dimCD5bright), and the increase of the resting fraction (CXCR4brightCD5dim). Compared to baseline, under ibrutinib therapy CLL cells also upregulated BCR and adhesion/homing proteins, and decreased the expression of BCR inhibitor proteins. Upon stimulation of the BCR with anti-IgM, the downstream path through pBTK and pPLCG2 was inhibited by ibrutinib, while conversely the downstream path through pAKT and pERK was still inducible throughout all the assessed timepoints. The proportion of CLL cells harboring nuclear localization of NF-kB progressively increased over time under ibrutinib. NF-kB nuclear localization was inducible throughout all the assessed timepoints by CD40L stimulation of the non-canonical NF-kB pathway, but not by anti-IgM stimulation of the BCR/canonical NF-kB pathway. Overall, 880 individual mutations were longitudinally discovered and monitored across a total of 121 sequential timepoints collected during ibrutinib treatment. Clonal evolution was observed in (67.7%) cases, a proportion rate previously documented in CLL treated with chemoimmunotherapy. Clonal evolution appeared to be heterogeneous involving different genes without a stereotypic targeting. Consistently, none of the main driver gene mutations was homogeneously selected or suppressed by ibrutinib suggesting that the biological adaptation of CLL cells under ibrutinib is not genetically driven. Clonal evolution propensity was not associated with any of the biomarkers of the disease, and it did not decrease over time under ibrutinib. Conclusions. Taken together these results suggest that residual CLL cells persisting under ibrutinib therapy adapt their phenotype by upregulating adhesion molecules, chemokine receptors and BCR molecules, and by maintaining a competence of BCR signaling through the PI3K/AKT/ERK pathway. The progressive selection of CLL cells having NF-kB in the nucleus, likely due to the BTK independent non-canonical NF-kB pathway, might explain their survival despite ibrutinib therapy. Finally, clonal evolution is not suppressed by ibrutinib chemotherapy, and despite does not seem to be directly involved in such adaptation process, may ultimately favor the acquisition of BTK and PLCG2 ibrutinib resistance mutations. Disclosures Zucca: Celltrion: Consultancy; AstraZeneca: Consultancy. Ghia:Sunesis: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; AbbVie, Inc: Honoraria, Research Funding; Acerta: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Gilead: Honoraria, Research Funding; BeiGene: Honoraria, Research Funding. Montillo:Janssen: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Speakers Bureau; AbbVie: Consultancy, Honoraria, Speakers Bureau; Roche: Consultancy, Honoraria, Research Funding. Tedeschi:Janssen: Consultancy, Speakers Bureau; Gilead: Consultancy; AbbVie: Consultancy. Gaidano:AbbVie: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Morphosys: Honoraria; Roche: Consultancy, Honoraria.

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Lenalidomide and Rituximab Maintenance Therapy after Front-Line Induction Chemoimmunotherapy in Chronic Lymphocytic Leukemia and Small Lymphocytic Lymphoma

Blood ◽

10.1182/blood-2019-124489 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 5470-5470

Author(s):

Julie E Chang ◽

Vaishalee P. Kenkre ◽

Christopher D. Fletcher ◽

Aric C. Hall ◽

Natalie Scott Callander ◽

...

Keyword(s):

Chronic Lymphocytic Leukemia ◽

Maintenance Therapy ◽

Research Funding ◽

Lymphocytic Leukemia ◽

Second Malignancies ◽

Front Line ◽

First Line ◽

11Q Deletion ◽

Line Chemotherapy

Introduction: Chronic lymphocytic leukemia (CLL) is incurable with standard therapy. With first-line chemotherapy, some patients (pts) may achieve durable remissions of many months/years. Lenalidomide (LEN) has improved progression-free survival (PFS) when given as maintenance (MNT) therapy after front-line chemotherapy (CALGB10404, CLLM1). The combination of LEN + rituximab (LR) has activity in relapsed CLL, hypothesizing benefit as MNT therapy after first-line chemotherapy. Methods: Adult pts ≥18 years with previously untreated CLL received induction bendamustine (B) 90 mg/m2 IV days 1 & 2 and rituximab (R) IV day 1 (375 mg/m2 cycle 1, then 500 mg/m2 cycles 2-6) for 6 treatment cycles (as few as 4 cycles allowed). MNT therapy with LR was initiated within 12 weeks after cycle 6, day 1 of BR. Criteria to start LR MNT included: neutrophils ≥1000/microliter (uL), platelets ≥75 K/uL, and creatinine clearance ≥40 mL/min. LEN was administered in 28-day cycles for 24 cycles, initially 5-10 mg daily continuous dosing, later modified to 5-10 mg on days 1-21 of each 28-day cycle in 6/2018 due to neutropenia and second malignancy risk. LEN was reduced to 5 mg every other day for toxicities at 5 mg/day. R 375 mg/m2 IV was given every odd cycle (total of 12 doses). Patients discontinuing LEN for any reason were allowed to continue R MNT per protocol. The primary endpoint is PFS with LR MNT therapy, calculated from the first day of MNT therapy until progressive disease (PD), death, or start of a new therapy. Secondary endpoints are response rate and overall survival. Results: Thirty-four pts have enrolled beginning 11/2013, with follow-up through 6/2019. Median age is 64 years, with 8 pts ≥70 years; 8 women and 26 men. CLL FISH panel is available on all pts: 14 with 13q (as sole abnormality), 9 with 11q deletion, 6 with trisomy 12, 4 with normal FISH panel and 1 with 17p deletion. Heavy chain mutation analysis is available on 11 pts: 8 unmutated, 2 mutated, 1 indeterminate. Thirty-one pts completed 4 (n=2) or 6 cycles of induction BR; 3 pts are receiving induction BR. Twenty-four pts have received MNT LR; 7 did not receive LR for reasons of PD during induction (n=2), infection (n=1), pt preference (n=2), renal insufficiency (n=1), and new carcinoma (n=1). MNT LR was completed in 7 pts; 9 pts are still receiving LR. Fourteen subjects have discontinued protocol therapy, 3 during induction due to PD (n=2) and infection (n=1), and 8 during MNT. Toxicities that led to discontinuation of LR were recurrent infections in 7 pts, including 2 events of PJP pneumonia; 4 pts had recurrent neutropenia with infections; 1 pt had neutropenia without infections. Response is assessable in 31 patients using the International Working Group Consensus Criteria. Best responses to treatment were: partial response 65% (22/34), complete response (CR)/unconfirmed CR 24% (8/34). The median number of MNT cycles received is 16. The dose intensity of LEN across total cycles received (n=278): 5 mg every other day (52.5%), 5 mg/day (43.9%), and 10 mg/day (3.6%). The most common reason for dose reduction or dose holding was neutropenia. Most common Gr 3/4 toxicities (reported as events Gr3/Gr4) during MNT therapy were: neutropenia (20/20), leukopenia (19/4), febrile neutropenia (3/1), and infections (11/-). The majority of Gr3 infections were pneumonia/respiratory (n=5). One event of disseminated herpes zoster occurred. Second malignancies during MNT included: basal cell CA (n=1), squamous cell carcinoma (n=5), and colon cancer (n=1). No unexpected second malignancies were observed in pts receiving LR. Two-year PFS (defined from day 1 of MNT therapy) is 90% (95% confidence interval [CI] 0.78-1), and the median follow-up for 24 patient who started maintenance therapy is 1.79 years (95% CI 1.53-2.7). There have been no deaths. Conclusion: The combination of LR is effective in sustaining remissions after a BR induction in previously untreated CLL, but with frequent neutropenia and infections even at low doses of LEN. Most patients discontinuing MNT did so due to neutropenia and/or infections. A shorter planned interval of MNT LR (i.e., 6-12 months) may confer similar benefit to extended dosing that is more tolerable. Pts at high risk for short remissions after front-line chemotherapy (e.g., unmutated heavy chain status, 11q deletion and/or failure to achieve minimal residual disease after induction) may be the populations for which LR MNT therapy is most appropriate. Disclosures Chang: Genentech: Research Funding; Adaptive Biotechnologies: Research Funding; Celgene: Research Funding. OffLabel Disclosure: Lenalidomide administered as maintenance therapy for first treatment of CLL/SLL.

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Impact of Idelalisib Treatment Interruption with or without Dose Reduction on Outcomes in Relapsed / Refractory Indolent Non-Hodgkin's Lymphoma and Chronic Lymphocytic Leukemia

Blood ◽

10.1182/blood-2019-124541 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 5468-5468

Author(s):

Shuo Ma ◽

Rebecca J Chan ◽

Lin Gu ◽

Guan Xing ◽

Nishan Rajakumaraswamy ◽

...

Keyword(s):

Overall Survival ◽

Chronic Lymphocytic Leukemia ◽

Board Of Directors ◽

Dose Reduction ◽

Clinical Outcomes ◽

Research Funding ◽

Treatment Interruption ◽

Lymphocytic Leukemia ◽

Hodgkin's Lymphoma ◽

Advisory Committees

Introduction: Idelalisib (IDELA) is the first-in-class PI3Kδ inhibitor and is approved as a monotherapy for relapsed or refractory (R/R) follicular lymphoma and in combination with rituximab for R/R chronic lymphocytic leukemia (CLL). We previously evaluated IDELA treatment interruption as a mechanism to mitigate treatment-emergent adverse events (TEAEs) and found that limited interruption with clinically appropriate re-challenging resulted in superior clinical outcomes. These findings did not comprehensively address the potential confound of interruptions inherently being associated with longer duration of therapy (DoT). Furthermore, the compound effect of IDELA dose reduction together with treatment interruption on IDELA efficacy was not assessed. Objectives: 1) To evaluate whether the benefit of IDELA interruption is retained in patients on therapy >180 days, a duration previously found to be associated with longer overall survival among patients who discontinued IDELA due to an AE; and 2) To compare clinical outcomes of patients who reduced IDELA dosing in addition to interrupting IDELA with those of patients who interrupted IDELA without additional dose reduction. Methods: Using data from Gilead-sponsored trials of patients with R/R indolent non-Hodgkin's lymphoma (iNHL) treated with IDELA monotherapy (N=125, Gopal et al., N. Engl. J. Med., 2014) or with R/R CLL treated with IDELA + anti-CD20 (N=110, Furman et al., N. Engl. J. Med., 2014; and N=173, Jones et al., Lancet Haematol., 2017), DoT, progression-free survival (PFS), and overall survival (OS) were compared between patients on IDELA therapy >180 days with vs. without interruption and between patients who experienced Interruption and Dose Reduction (IDR) vs. patients who experienced Interruption but NoDose Reduction (INoDR) at any point during IDELA treatment. Interruption was defined as missing at least one IDELA treatment day due to an AE and dose reduction could have occurred before or after the first interruption. PFS and OS were estimated using the Kaplan-Meier method and were compared using a log-rank test. Results: Sixty-nine of 125 patients with R/R iNHL (55.2%) and 222 of 283 patients with R/R CLL (78.4%) remained on IDELA therapy >180 days with 29 (42.0%) and 103 (46.4%) of them, respectively, experiencing interruption on or after day 180 (Table 1). The proportions of patients with interruption before day 180 were similar within each of these populations. Among patients on therapy >180 days, those with treatment interruption on or after 180 days had a longer median (m) DOT than patients without interruption (Table 1). Both PFS and OS were longer in CLL patients who interrupted compared to those who did not interrupt (mPFS=28.9 mos. vs. 17.3 mos. and mOS=not reached [NR] vs. 40.4 mos. for with interruption vs. without interruption, respectively, Table 1 and Figure 1). In patients with iNHL, no difference was observed in PFS or OS between patients who interrupted vs. those who did not (Table 1). Of patients who experienced at least one AE-induced interruption at any point during IDELA therapy (n=63 iNHL and n=157 CLL), 47 iNHL patients (74.6%) and 84 CLL patients (53.5%) also had dose reduction. Two iNHL patients (1.6%) and 5 CLL patients (1.8%) had IDELA dose reduction but no interruption. Both iNHL and CLL patients with IDR experienced a similar PFS compared to patients with INoDR (mPFS=16.5 mos. vs. 14.2 mos. for iNHL and 21.8 mos. vs. 22.1 mos. for CLL with IDR vs. INoDR, respectively, Table 2). However, OS was longer in both iNHL and CLL patients with IDR compared to INoDR (mOS=61.2 mos. vs. 35.3 mos. for iNHL and NR vs. 42.4 mos. for CLL, respectively, Table 2; CLL patients shown in Figure 2). Discussion: IDELA treatment interruption is not associated with rapid clinical deterioration, as observed with some B-cell receptor signaling pathway inhibitors. No clear relationship between IDELA DoT and frequency of interruption was observed. When normalized for DoT >180 days, IDELA treatment interruption retained its clinical benefit in the CLL population. When utilized together with IDELA interruption, dose reduction did not lead to inferior clinical outcomes but instead extended OS in both iNHL and CLL populations. Adherence to treatment interruption and dose reduction guidance as outlined in the IDELA USPI may optimize IDELA tolerability and efficacy for patients with iNHL and CLL. Disclosures Ma: Janssen: Consultancy, Speakers Bureau; Pharmacyclics: Consultancy, Research Funding, Speakers Bureau; Gilead: Research Funding; Abbvie: Research Funding; Juno: Research Funding; Incyte: Research Funding; Xeme: Research Funding; Beigene: Research Funding; Novartis: Research Funding; Astra Zeneca: Consultancy, Research Funding, Speakers Bureau; Kite: Consultancy; Acerta: Research Funding; Bioverativ: Consultancy; Genentech: Consultancy. Chan:Gilead Sciences, Inc.: Employment, Equity Ownership. Gu:Gilead Sciences, Inc.: Employment. Xing:Gilead Sciences, Inc.: Employment. Rajakumaraswamy:Gilead Sciences, Inc.: Employment. Ruzicka:Gilead Sciences, Inc.: Employment. Wagner-Johnston:Gilead: Membership on an entity's Board of Directors or advisory committees; ADC Therapeutics: Membership on an entity's Board of Directors or advisory committees; Jannsen: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees.

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BAX-Mutated Clonal Hematopoiesis in Patients on Long-Term Venetoclax for Relapsed/Refractory Chronic Lymphocytic Leukemia

Blood ◽

10.1182/blood-2020-137775 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 9-10

Author(s):

Piers Blombery ◽

Ella R Thompson ◽

Xiangting Chen ◽

Tamia Nguyen ◽

Mary Ann Anderson ◽

...

Keyword(s):

Advisory Committee ◽

Board Of Directors ◽

Research Funding ◽

Lymphocytic Leukemia ◽

Advisory Committees ◽

Clonal Hematopoiesis ◽

Eliza Hall Institute ◽

Hall Institute ◽

Over Time

Venetoclax (Ven) is an effective element of treatments for chronic lymphocytic leukemia (CLL) with high response rates observed in the upfront and relapsed/refractory (R/R) settings. In addition to inducing apoptosis in CLL cells, Ven also induces apoptosis within normal and malignant myeloid lineage populations (accounting for its efficacy in the treatment of acute myeloid leukemia). We investigated the effects of Ven outside the target tumor compartment in patients (pts) with CLL receiving long-term continuous Ven and make the novel observation of the development of BAX-mutated clonal hematopoiesis in this heavily pre-treated patient group. 92 pts with CLL receiving continuous non time-limited Ven have been treated at our institutions on clinical trials. Of these, 41 had sufficient (>6 mo) follow up (median 70; range 14-95 mo) and suitable samples available for further analysis. 38/41 (93%) pts had received previous treatment with alkylators and/or fludarabine. In order to assess the non-CLL compartment in these 41 pts we identified those with peripheral blood or bone marrow aspirate samples taken during deep response to Ven demonstrating either minimal (<5%) or no CLL involvement by flow cytometry (sensitivity 10-4). We initially performed unique molecular index (UMI)-based targeted next generation sequencing of apoptosis pathway genes as well a panel of 60 genes recurrently mutated in lymphoid and myeloid malignancy. From these 41 pts we identified mutations in the apoptosis effector BAX in samples from 12 (29%). 20 different BAX mutations were observed across these 12 pts at variant allele frequencies (VAF) consistent with their occurrence in the non-CLL compartment. Mutations included frameshift, nonsense, canonical splice site and missense mutations occurring in key structural elements of BAX consistent with a loss-of-function mechanism (Fig 1A). Interestingly, an enrichment of missense and truncating mutations predicted to escape nonsense mediated decay were observed at the C-terminus of the BAX protein affecting the critical α9 helix. Mutations in this region have previously been shown in cell lines to cause aberrant intracellular BAX localization and abrogation of normal BAX function in apoptosis (Fresquet Blood 2014; Kuwana J Biol Chem 2020). For comparison, NGS targeted sequencing for BAX mutations was performed on samples from cohorts of pts with (i) myeloid or lymphoid malignancy (n=80) or (ii) R/R CLL treated with BTK inhibitors (n=15) after a similar extent of preceding chemotherapy. Neither of these cohorts had previous exposure to Ven. BAX mutations were not detected in any samples from these pts. Longitudinal sampling from pts on Ven harboring BAX mutations in the non-CLL compartment was performed to further understand compartment dynamics over time (in 9 pts over 21-93 months of follow up). Multiple pts demonstrated a progressive increase in VAF of single BAX mutations over time to become clonally dominant within the non-CLL compartment and with observed VAFs consistent with their presence in the myeloid compartment. Mutations in other genes implicated in clonal hematopoiesis and myeloid malignancy including ASXL1, DNMT3A, TET2, U2AF1 and ZRSR2 were also detected in these pts samples. Targeted amplicon single cell sequencing (Mission Bio) demonstrated the co-occurrence of clonally progressive BAX mutations within the same clones as mutations in DNMT3A and ASXL1 as well as the existence of further BAX mutations at low VAF outside these dominant clones which remained non-progressive over time (Fig 1B). In addition, fluctuations in the presence and VAF of myeloid-disease associated mutations was noted with Ven exposure. In aggregate these data are consistent with the existence of a selective pressure within the myeloid compartment of these pts and an interplay of BAX with other mutations in determining survival and enrichment of these clones over time with ongoing Ven therapy. In summary, we have observed the development of BAX-mutated clonal hematopoiesis specifically in pts with CLL treated with long-term Ven. These data are consistent with a multi-lineage pharmacological effect of Ven leading to a survival advantage for clones harboring BAX mutations within the myeloid compartment during chronic Ven exposure. Finally, our data support the further investigation of BAX mutations as a potential resistance mechanism in myeloid malignancies treated with Ven. Disclosures Blombery: Invivoscribe: Honoraria; Amgen: Consultancy; Janssen: Honoraria; Novartis: Consultancy. Anderson:Walter and Eliza Hall Institute: Patents & Royalties: milestone and royalty payments related to venetoclax.. Seymour:Celgene: Consultancy, Honoraria, Research Funding; F. Hoffmann-La Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy; Mei Pharma: Consultancy, Honoraria; Morphosys: Consultancy, Honoraria; Nurix: Honoraria; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Tam:Janssen: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; BeiGene: Honoraria. Huang:Servier: Research Funding; Walter and Eliza Hall Institute: Patents & Royalties: milestone and royalty payments related to venetoclax.; Genentech: Research Funding. Wei:Janssen: Honoraria, Other; Walter and Eliza Hall Institute: Patents & Royalties; AMGEN: Honoraria, Other: Advisory committee, Research Funding; Novartis: Honoraria, Research Funding, Speakers Bureau; Astellas: Honoraria, Other: Advisory committee; Pfizer: Honoraria, Other: Advisory committee; Macrogenics: Honoraria, Other: Advisory committee; Abbvie: Honoraria, Other: Advisory committee, Research Funding, Speakers Bureau; Genentech: Honoraria, Other: Advisory committee; Servier: Consultancy, Honoraria, Other: Advisory committee; Celgene: Honoraria, Other: Advisory committee, Speakers Bureau; Astra-Zeneca: Honoraria, Other: Advisory committee, Research Funding. Roberts:Janssen: Research Funding; Servier: Research Funding; AbbVie: Research Funding; Genentech: Patents & Royalties: for venetoclax to one of my employers (Walter & Eliza Hall Institute); I receive a share of these royalties.

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