Unmutated IGHV Research Articles

Anti-PD-L1/PD-L2 therapeutic vaccination in untreated chronic lymphocytic leukemia patients with unmutated IgHV.

Chronic lymphocytic leukemia (CLL) patients with unmutated immunoglobulin heavy chain (IgHV) are at risk of early disease progression compared to patients with mutated IgHV. As a preventive strategy, we treated 19 previously untreated CLL patients with unmutated IgHV in a phase 1/2 trial (clinicaltrials.gov, NCT03939234) exploring the efficacy and toxicity of a therapeutic cancer vaccine containing peptides derived from programmed death ligand 1 (PD-L1) and ligand 2 (PD-L2), hoping to restore immunological control of the disease. According to the International Workshop on Chronic lymphocytic Leukemia (iwCLL) response criteria, no patients obtained a response; however, during follow-up, one patient had complete normalization of the peripheral lymphocyte count and remained in biochemical remission after a follow-up time of 15 months. At the end of treatment, one patient had progressed, and 17 patients had stable disease. During follow-up with a median time of 23.5 months since inclusion, seven patients had progressed, and eight patients had stable disease. The median time to first treatment (TTFT) from diagnosis was 90.3 months with a median follow-up time of 50.1 months. This apparent favorable outcome in TTFT needs to be investigated in a randomized setting, as our population may have been biased. More than 80% of patients obtained vaccine-specific immune responses, confirming the immunogenicity of the vaccine. The vaccine was generally well tolerated with only grade I-II adverse events. Although there were some signs of clinical effects, the vaccine seems to be insufficient as monotherapy in CLL, possibly due to a high tumor burden. The efficacy of the vaccine should preferably be tested in combination with novel targeted therapies or as a consolidating treatment.

Identification of Three Unique Clusters of Serum Proteins with Distinctive Functionalities in IGHV-Mutated MBL

Background. CLL-like monoclonal B-cell lymphocytosis (MBL) is considered a requisite precursor of CLL. Since MBL is also associated with inflammatory disorders, other cancers, and increased incidence of infections (Landgren et al, 2007; Moreira et al, 2013; Solomon et al, 2016), an underlying immune alteration might be at the root of the condition's onset and progression to CLL. Patients with CLL whose clone expresses mutated (M-CLL) and unmutated (U-CLL) IGHV genes differ in inflammatory profiles, with the latter exhibiting a more activated immune system, in line with the distinct capabilities of the two CLL subtypes to interact with the microenvironment with M-CLL being more anergic. Here, we studied the serum protein profiles in MBL, CLL patients, and age-matched healthy donors (HD). Since a sufficient number of MBL subjects with unmutated IGHV was not available, only MBL with mutated IGHV (M-MBL) and M-CLL patients were analyzed. Objectives. 1. Compare serum proteomic profiles of the three subsets of individuals. 2. Identify protein clusters more restricted to M-MBL. Methods. In all, 34 subjects were studied: 10 M-MBL, 12 M-CLL, and 12 HD. All individuals were treatment naive at sample collection, and all MBL subjects remained stable over a median follow-up of 53 months. Serum protein levels were quantified using a library of modified single-stranded DNA aptamers (SOMAmers) that measure 1,310 protein targets (SomaLogic). P-values <0.05 were required to consider protein levels as differentially expressed (DE) between groups. The protein-specific STRING database v11.5 was used for analyses. Functional enrichments were selected according to i) confidence > 0.4; ii) lowest significant (< 0.05) FDR P-values; iii) network description, focusing only on informative disease-related pathways. The Markov Cluster (MCL) algorithm was used to identify clusters of non-redundant, upregulated proteins related to functionally-associated networks. Serum levels of selected molecules were validated using the U-PLEX Platform (MSD) in 24 HD, 29 M-MBL and 25 M-CLL. Results: Levels of 34 proteins were DE in MBL vs. HD [19 upregulated (u), 56%; and 15 downregulated (d)]; 288 in CLL vs. HD [16u, 6%; and 272d]; and 419 in MBL vs. CLL [411u, 98%; and 8d]. U-PLEX assays validated the significantly increased levels of IL8 (P = 0.020) and CXCL11 (P = 0.038) in MBL vs. HD and IL4 (P = 0.029) in MBL vs. CLL. STRING analysis of the DE proteins between groups is shown in Table 1. Pathways related to viral infections were only highlighted in MBL vs. HD. Cytokine activity, receptor signaling, and the PI3K-Akt pathway that promotes proliferation, were detected in both MBL vs. HD (mainly upregulated) and CLL vs. HD (mostly downregulated). The last three pathways were also observed for MBL vs. CLL (upregulated in MBL). To unravel the previous comparison, the MCL algorithm was used, and this disclosed 3 main clusters of non-redundant, upregulated proteins in MBL (Table 2). Cluster #1 involved pathways related to receptor binding (including growth factor receptors such as the ErbB family) and signal transduction, with an emphasis on the PI3K-Akt pathway. The activation of these pathways promotes cell survival and migration. Cluster #2 included cell division pathways and upregulated HMGB1 and MYC, both allowing gene transcription and proliferation. Cluster #3 concerned immune system activation, in particular inflammatory responses involving innate immune cells, viral interactions, IL17, and the JAK-STAT pathway, the latter playing a major role in cytokine receptor signaling. Conclusions: The serum proteins in M-MBL suggest immune stimulation, which underwent considerable change after transition to M-CLL. This highlights an evolving serum proteome functionality with a slight activation of the immune system in MBL that declines upon transition to CLL. Clustering analysis identified 3 non-redundant, upregulated protein clusters in M-MBL compared to M-CLL. These findings suggest immune stimulation as a characteristic feature in MBL that is not operative in CLL and point out 3 groups of distinct pathological networks that may have a role in disease onset and tumor control. Future studies, focusing on specific cell subsets, will be performed to disclose the main cell orchestrators and their exact role within each cluster, to ultimately develop preemptive strategies. Acknowledgments. GB was supported by Fundación Alfonso Martín Escudero. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Molecular Landscape of Chronic Lymphocytic Leukemia Using Targeted Gene Panel Sequencing

Introduction Chronic lymphocytic leukemia (CLL) is a clinically heterogeneous disease with various genetic abnormalities that can affect the treatment and survival of patients. Recently, by the advent of next-generation sequencing (NGS) techniques recurrently mutated genes have been described in CLL. Driver gene mutations such as NOTCH1, SF3B1, TP53, and MYD88 have been considered to have prognostic impact in CLL. The aim of this study was to detect pathogenic variants of commonly mutated genes in CLL patients and to explore their associations with IGHV mutational status and cytogenetic abnormalities. Patients and Methods The samples were collected from bone marrow or peripheral blood of 124 CLL patients. Genomic DNA was isolated using QIAamp Blood Mini kit. NGS analysis was performed using Twist Custom Panel and bidirectional sequencing with a minimum coverage of 1000x on Illumina NextSeq according to the manufacturers’ instructions. Data were analyzed by NextGene software. The following 27 recurrently mutated CLL genes were studied: PIK3CD, PIK3CA, SF3B1, MYD88, FBXW7, BRAF, NOTCH1, PTEN, BIRC3, PTPN6, MAP2K1, TP53, STAT5B, STAT3, CD79B, TCF3, MAPK1, DDX3X,ATM, BCL2, BTK, KRAS, NRAS, CARD11, CXCR4, PLCG2, POT1. Variants below 5% variant allele frequency (VAF) were filtered out from the analysis. Variants were considered subclonal with 5-10% VAF and clonal when VAF was >10%. Classification of variants were performed according to the American College of Medical Genetics and Genomics (ACMG) criteria. Results Our NGS study revealed a total of 96 variants in 124 CLL patients. Overall, 63/124 patients (50.8%) harbored at least one mutation, the majority of them (60/96, 62.5%) was clonal. In 36 patients only one pathogenic variant was detected, while 88 patients carried two or more (2-4) genetic alterations. The most frequently mutated gene was the NOTCH1, followed by TP53, SF3B1, FBXW7, and BRIC3. Subclonal variants were also detected in 36/124 patients (29%), particularly in NOTCH1,FBXW7, BIRC3, and PIK3CA genes. TP53 and NOTCH1 variants occured mostly in unmutated IGHV CLL cases. Patients with mutated IGHV harbored mainly FBXW7 and BIRC3 mutationss. FBXW7 variants were detected in 9/125 (7%) patients, that is a higher frequency compared to other studies. Fluorescence in situ hybridization (FISH) was performed in 113 cases. The majority of these patients (84 cases, 74%) had one or more cytogenetic abnormality. In this cohort, 13q deletion was the most common aberration (65%, 55/84 patients), followed by 11q deletion (26%, 22/84 patients) and 17q deletion (14%, 12/84 patients). Deletion of 17p co-occured with TP53 single nucleotide variants in 10 of 12 patients. SF3B1, NOTCH1, BIRC3 and TP53 variants occured with 11q deletion in 10 cases. Trisomy 12 was detected with NOTCH1, BIRC3 and FBXW7 variants, and showed negative association with unfavorable SF3B1 mutations. Conclusions Our results confirmed the presence of high number of clonal and subclonal variants in the most frequently mutated genes (NOTCH1, TP53, SF3B1, FBXW7, BIRC3). TP53, NOTCH1 and SF3B1 mutations were enriched with unfavorable biologic factors, as they were found to be associated with unmutated IGHV and cytogenetic aberrations, such as del17p, del11q and trisomy 12. Cases with NOTCH1 variants harbored all types of the investigated cytogenetic alterations (del13q, del11q, de17p, trisomy 12) and were associated exclusively with unmutated IGHV. TP53 variants occured mostly in unmutated IGHV CLL cases together with del17p. Patients with SF3B1 variants showed del11q, del13q and mostly unmutated IGHV. FBXW7 variants enriched in both of unmutated and mutated IGHV cases and harbored del13q, de17p and trisomy 12. FBXW7 and NOTCH1 pathogenic variants have the same biological consequences in CLL, therefore presence of FBXW7 mutations may have clinical relevance regarding anti-CD20 therapy. Taken together, these NGS results complemented with the study of IGHV mutational status and cytogenetic data can contribute to better prognostic workup and management of our CLL patients.

Final Results of the Phase 1/2 Study of Acalabrutinib Monotherapy in Treatment-Naive Chronic Lymphocytic Leukemia with >6 Years of Follow-up

Background: Acalabrutinib is a next-generation, covalent Bruton tyrosine kinase inhibitor approved for the treatment of patients with treatment-naive (TN) or relapsed/refractory chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). A previous analysis of the phase 1/2, multicenter ACE-CL-001 study (NCT02029443) demonstrated durable responses and good long-term tolerability of acalabrutinib as first-line therapy in patients with CLL at a median follow-up of 53 months (Byrd et al. Blood. 2021;137:3327-38). Here, we report the final analysis in the TN cohort of that study, the longest running study of acalabrutinib, with over 6 years of follow-up. Methods: Patients included in the study were aged ≥18 years with TN CLL/SLL who met the 2008 iwCLL criteria for treatment, were inappropriate for or declined standard chemotherapy, and had ECOG performance status 0-2. All TN patients were treated in the phase 2 portion of the study and received acalabrutinib 100 mg twice daily (BID) or 200 mg once daily (QD), later switching to 100 mg BID, until progressive disease (PD) or unacceptable toxicity. The primary endpoint was safety. Secondary endpoints included investigator-assessed overall response rate (ORR), time to response (TTR), duration of response (DOR), and progression-free survival (PFS), with a post hoc analysis of event-free survival (EFS). Results: Ninety-nine patients (n=62 100 mg BID; n=37 200 mg QD) were treated. The median age was 64 years; 47% of patients had Rai stage 3-4 disease, 10% had del(17p), 14% had TP53 mutation, 17% had del(11q), 62% had unmutated IGHV, and 18% had complex karyotype. At the final data cut-off date of July 15, 2021, the median study follow-up was 73.7 months (range 0.92-82.4), and 70 (71%) patients remain on acalabrutinib treatment. The most common reasons for treatment discontinuation were adverse events (AEs) (10%) and PD (6%). The most common AEs (Table 1) were consistent with those reported in the prior update (53-month median follow-up). The only grade ≥3 AEs with a ≥50% increase in incidence since the prior update were pneumonia (4% [prior update] vs 8%) and syncope (4% [prior update] vs 6%). AEs that led to treatment discontinuation were amyotrophic lateral sclerosis, angiosarcoma, cardiac failure, cerebral hemorrhage, gastric hemorrhage, glioblastoma multiforme, non-cardiac chest pain, prostate cancer, sepsis, small cell lung cancer, and urinary tract infection (in 1 patient each). All-grade and grade ≥3 events of clinical interest included infection (87% and 19%, respectively), bleeding events (74%, 7%), major bleeding events (8%, 7%), and hypertension (29%, 13%). Atrial fibrillation/flutter occurred in 6% of patients (3% grade ≥3). Second primary malignancies excluding non-melanoma skin (all grades) occurred in 14% of patients Two deaths were reported (cardiac failure, n=1; multiple organ dysfunction syndrome, n=1); neither was considered treatment related. ORR was 97% (9% complete response; 88% partial response). Median TTR was 3.7 months (range 1.7-22.1). Median DOR was not reached; the estimated 66-month DOR rate was 89% (95% CI 80-94). ORR of 100% was seen across high-risk groups: del(17p) (9/9), del(11q) (15/15), unmutated IGHV (57/57), and complex karyotype (12/12). Median PFS was not reached; the estimated 72-month PFS rate was 87% (95% CI 77-93; Figure 1). The estimated 72-month EFS was 78% (95% CI 68-85). Reported EFS events overall included AEs (n=10/99, 10%), disease progression (n=9/99, 9%), and new anticancer therapy (n=3/99, 3%). Conclusions: The final data from ACE-CL-001 further support the long-term efficacy and safety of acalabrutinib monotherapy, with high response rates and rapid, durable responses seen in patients with TN CLL regardless of high-risk genomic features. With over 6 years of follow-up, this study firmly establishes the tolerability and safety profile of acalabrutinib seen consistently in subsequent studies, with a low incidence of atrial fibrillation/flutter seen and no new long-term safety issues identified. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Predictive and Prognostic Molecular Biomarkers in Familial Chronic Lymphocytic Leukemia: A Pilot Monocentric Study

Background: Chronic lymphocytic leukemia (CLL) is the most common leukemia in the western world and the median age at diagnosis is 70 years. Family history of hemopathies and, more consistently, of CLL is a risk factor to develop the disease. The prevalence of blood diseases, and more specifically of CLL, in relatives of patients with CLL has been estimated at 13% and 7%, respectively. Familial CLL is defined as the presence of at least one first degree relative with CLL. Previous studies hypothesize the phenomenon of anticipation, which is the earlier onset and more aggressive course of a disease in the second generation of relatives, in familial CLL. Aims: The primary end point is to determine the prevalence of familial CLL in our court of patients with CLL and to confirm the phenomenon of anticipation. The secondary endpoints involve the comparison of the prevalence of clinical features and molecular biomarkers between familial and sporadic CLL; the comparison of the impact of clinical features and molecular biomarkers on patients’ clinical course in terms of time to treatment (TTT), time to next treatment (TTNT), progression-free survival (PFS) and overall survival (OS) between familial and sporadic CLL; the evaluation of response to treatment (ORR) in familial CLL compared to sporadic cases. Patients and methods: This is a retrospective monocentric study which consists of clinical and biological data collection from all patients with familial CLL. We enrolled 500 patients, which included 46 familial CLL and 454 sporadic CLL cases, diagnosed between January 1987 and April 2022. Patients’ characteristics were described by frequency tables for qualitative variables and position indicators for quantitative variables. The associations with clinical-biological parameters were analyzed using Chi-square or Fisher's exact test for the variables qualitative and Wilcoxon or Kruskal-Wallis test for quantitative variables. Survival was estimated with the Kaplan Meier method and compared by the log rank test. Results: The prevalence of familial CLL and familiarity for any other hemopathy in our population was 9.4% and 20% respectively. The median age at diagnosis was 65 years old in sporadic and 59 years old in familial CLL (p=0.018). Focusing on patients with familial CLL, our data confirmed the phenomenon of anticipation. In the first generation of patients with familial CLL (including father, mother, and older siblings), the median age at diagnosis was 69 years old (range 50-90), while in the second generation (including children and younger siblings) the median age at diagnosis was 57 years old (range 31-83). The mean difference between the two populations was of 12.6 years (17.5 years lower limit and 7.7 years upper limit), with a 95% confidence interval (p=0.00003). Concerning the IgHV mutational status, sporadic CLL showed mutated IgHV in 65% of the cases and unmutated IgHV in 35%, while familial CLL showed mutated IgHV in 35% of the cases and unmutated IgHV in 65% (p<0.001). No statistically significant difference was instead found for FISH nor for molecular biomarkers, including TP53, NOTHC1, BIRC3 and SF3B1 (Table 1). In our cohort, the time to treatment, time to next treatment and progression free survival for familial CLL appear to be shorter than for the control group, but those results are not statistically significant at the log rank test. Moreover, the overall response rate was significantly lower in patients with familial CLL: this data has never been reported by any study and it further confirms the rather aggressive course of the disease (Table 1). Familial CLL did not show any significant difference in overall survival compared to sporadic CLL. Conclusions: We confirmed the phenomenon of anticipation in our population. Moreover, we found higher rate of unmutated IgHV in familial CLL compared to sporadic controls, which would underlie a more aggressive course of the disease in this subset of patients. To define the molecular characteristics of familial CLL and to improve the significance of the survival analysis, we need to study a larger population of patients. Our monocentric experience is meant to be a pilot study which will be extended to other centers in Italy and opens the way to a better understanding of CLL clustering in families. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Chronic Lymphocytic Leukemia Treatment: Single Center Experience

Background: Chronic lymphocytic leukemia (CLL) is relatively uncommon in the Middle East, with a younger age at diagnosis and different clinical characteristics compared to the West. There is little research on CLL in this region. This study aims to evaluate widely used prognostic markers and examine treatment outcomes of CLL patients in the Kuwait Cancer Control Center (KCCC), the only cancer center in Kuwait. Methods: This is a retrospective analysis of unselected 141 CLL patients receiving treatment in the KCCC. Diagnostic and treatment guidelines in our center were in accordance with the International Workshop on CLL criteria. Results: The median age of those patients at diagnosis was 58 years (IQR, 51-65), with 60% of patients under the age of 60. The male to female ratio in this group was 3.3:1. Median absolute lymphocyte count was 51x109/L (IQR, 51-65), and the median hemoglobin and platelet count were 11.8 g/dL (IQR, 10.1-13.8) and 170x109/L (IQR, 129-222). FISH analysis was performed in 118 patients, of which 9% (11) demonstrated del17p. Del13q and trisomy 21 were detected in 31% (36) and 26% (31) patients, respectively. IGHV mutational status was determined in 80 patients, 25% (20) were mutated, and 75% (60) were unmutated. When it comes to treatment, 47% (65) of patients were on FCR regimen, while 11% (15) and 12% (16) were receiving BR and CR, respectively. Approximately 15% (21) of patients in our study were on a BTKi. In 105 patients, the median progression-free survival (PFS) was 44.2 months [95% CI: 36-61.5], with a PFS rate of 48% and 32% at 25 and 50 months, respectively. In 121 patients with no history of progression or treatment in our study cohort, 41.5% and 21% progressed or received treatment at 25 and 50 months, respectively, with a median time to first progression or treatment around 37.6 months [95% CI: 29.1-49.5]. Examining 103 patients with prior history of progression or treatment, 34% and 13% progressed again or required a second course of treatment at 25 and 50 months, respectively, with a median time to second progression or treatment around 65.5 months [95% CI: 40.5-NA]. Those receiving chemoimmunotherapy exhibited a higher median PFS of 93 months [95% CI: 83-NA] compared to those receiving a BTKi with a median PFS of 42 months [95% CI: NA-NA]. However, the difference was not statistically significant (p=0.34). IGHV mutation status was significantly associated with OS (p=0.044) but not PFS (p=0.28). Those with unmutated IGHV had an inferior outcome compared to their mutated counterparts with OS rates at 50 months, around 15% and 25%, respectively, PFS rates were also lower in the unmutated compared to a mutated group, 21% vs. 31% at 50 months, respectively, and PFS medians around 49 [95% CI: 36.4-NA] and 94.5 [95% CI: 94.5-NA], respectively. Multivariate cox regression analysis on OS was not significant (p=0.160). None of the individual treatment regimens were significant predictors of OS compared to the reference (BR), except FCR. Treatment with FCR was associated with a hazard ratio of 0.11 (p = 0.011). Unmutated IGHV status, presence of del17p, and age greater than 60 were all associated with greater hazard ratios, but none were significant predictors of OS. Conclusion: Our CLL treatment group is younger. Unmutated IGHV was associated with a poor prognosis, consistent with the literature. However, treatment with BTKis was not associated with superior outcomes compared to CIT; however, this study is not powered to detect a difference between the two arms. Those receiving FCR had the best survival outcome compared to those receiving other therapies. Keywords: Chronic Lymphocytic Leukemia, Treatment Outcomes, Kuwait, Middle East Funding Agency: Kuwait Foundation for the Advancement of Science, Grant number: PR1713MM03 Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Early Treatment with Ofatumumab in Patients with High-Risk CLL

Introduction Early treatment initiation for patients with high-risk CLL has not been shown to be associated with clinical benefit in studies utilizing rituximab and rituximab in combination with alemtuzumab. Ofatumumab is a fully human monoclonal antibody targeting CD20. It is well-tolerated and has improved target binding and cytotoxicity compared to rituximab. We therefore sought to evaluate the efficacy of ofatumumab as early treatment in patients with high-risk CLL. Methods This was a single-arm, open label, phase II trial for treatment-naïve, watch-and-wait patients with high-risk for progression to need treatment. Based on currently available models, high-risk CLL was defined as presence of one or more of the following: Rai stage 2 disease or Rai stage 0-1 with disease related fatigue, β2M ≥ 3mg/L, ALC ≥ 25K/µL, unmutated IGHV, ZAP70-positive, CD38-positive, or FISH with del(11q) or del(17p). Patients who met 2008 iwCLL criteria for treatment were excluded. The primary objective was overall response rate (ORR) with secondary objectives of progression-free survival (PFS), time-to-next treatment (TTNT), and overall survival (OS). Treatment consisted of a total of 8 weekly doses of ofatumumab. The first weekly dose was 300mg to reduce infusion reactions, subsequently ofatumumab 1000mg was then administered weekly for 7 weeks. Results Between 04/2011 and 06/2015, 44 pts were enrolled in the study and initiated treatment. The median age at study entry was 60 years with a median time from diagnosis to study entry of 15.3 mo. The median ALC, HGB and PLT counts were 20.1K/µL, 14mg/dL, and 166K/µL, respectively. The median LDH was 481U/L (range 345 - 855). When characterized based on FISH alterations, 19(43%) pts had del(13q), 7(16%) pts had trisomy 12, 8(18%) pts had del(11q), 3(7%) pts had del(17p), and 7(16%) pts had no abnormalities. When characterized based on other high-risk features: 24(55%) pts had unmutated IGHV, 21(48%) pts were ZAP70(+), 15(34%) pts were CD38(+), 6(14%) had elevated β2M, and 21(48%) had an ALC over 25K/µL. The ORR to ofatumumab (complete + partial remission) was 63% with 3(7%) pts attaining undetectable MRD status at 10-4 sensitivity. At a median follow up of 8 years, the median PFS, TTNT, and overall survival (OS) were 16.3 mo, 42.8 mo, and not reached. Thirty (68%) pts went on to receive further treatment (19 pts on BTK based regimens, 2 pts received venetoclax monotherapy, 5 pts received combined venetoclax and ibrutinib, 3 pts received chemoimmunotherapy, and 1 pt received obinutuzumab monotherapy). This regimen of early treatment with ofatumumab was well tolerated. The most common adverse reaction was infusion reactions occurring in 16 pts (36%) with all reactions being amendable to antihistamine and/or steroid treatment. In all of these pts the infusion was restarted. One pt had to discontinue ofatumumab treatment after the second infusion due to autoimmune hepatitis. Conclusion In a population of patients with CLL at high-risk for proceeding to treatment, early treatment with ofatumumab resulted in a PFS and TTNT of 16.3 mo and 42.8 mo, respectively. The PFS was similar to that of similarly designed trials with rituximab monotherapy and rituximab in combination with alemtuzumab, respectively. Further internal matched analysis is being conducted to compare time to second treatment. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Combined Ibrutinib and Venetoclax for First-Line Treatment of Patients with Chronic Lymphocytic Leukemia (CLL): 4-Year Follow-up Data

Background: Ibrutinib (IBR) and venetoclax (VEN) combination is an effective therapy for patients (pts) with CLL. We previously reported results of the first-line cohort of a phase II trial of combined IBR and VEN for high-risk pts with CLL (Jain, NEJM 2019, JAMA Oncology 2021). Here we report updated data for 120 pts (80 pts in the original published cohort and 40 pts in an expansion cohort) with a median follow-up of 4 years. Methods: Pts with previously untreated CLL meeting IWCLL treatment criteria were enrolled. All pts had at least one high-risk feature: del(17p), mutated TP53, del(11q), unmutated IGHV, or age ≥65 years. Pts received IBR 420 mg daily for 3 cycles followed by addition of VEN (weekly dose-escalation to 400mg daily). Combined therapy was given for 24 cycles (28 days/cycle). Pts with bone marrow (BM) undetectable MRD (U-MRD) (flow cytometry; sensitivity 10-4) at 24 cycles of combined therapy discontinued both VEN and IBR; MRD+ pts continued IBR. A trial amendment allowed an additional 12 cycles of combined VEN and IBR for pts who remained BM MRD+ after Cycle 24. Response assessments included BM and CT studies (2008 IWCLL criteria). U-MRD was defined as <0.01%; low MRD+ 0.01% to <1%; high MRD+ ≥1%. Progression-free survival (PFS) was assessed as the time from the start of study drug to CLL progression, Richter transformation, or death from any cause. Blood MRD was monitored every 6 months after active therapy. Results: Between August 2016 and February 2019, a total of 120 pts were enrolled. Baseline characteristics are shown in Table 1. The median follow-up is 48.8 months. Six pts came off study during 1st 3 cycles of IBR monotherapy; 114 pts initiated VEN. After 12 cycles of the combination, 62/120 (52%) achieved BM U-MRD remission; 43/120 (36%) were BM MRD-positive (low MRD+, n=35; high MRD+, n=8). After 24 cycles of the combination, 77/120 (64%) achieved BM U-MRD remission; 24/120 (20%) were BM MRD+ (low MRD+, n=23; high MRD+, n=1). Overall, 86/120 (72%) achieved BM U-MRD as the best response. We evaluated baseline pt and disease characteristics (age, gender, IGHV mutation status, CLL FISH panel, complex karyotype, TP53 mutation, del(17p)/TP53 mutation) and rate of bone marrow U-MRD at 6 months, 12 months and at any time during the combined IBR+VEN treatment. At 6 months of combined therapy, presence of TP53 mutation was associated with a lower rate of bone marrow U-MRD (p=0.03); however, none of the aforementioned characteristics, including TP53 mutation were associated with marrow U-MRD responses at 12 months or with best MRD response at any time during the combined therapy. There was a trend towards lower U-MRD rate among pts with mutated IGHV vs. unmutated IGHV at 12 month (p=0.09) and as best response (p=0.09). The 4-year PFS is 94.5% (95% CI, 90.3%-98.9%) and 4-year OS is 96.6% (95% CI, 93.3%-99.9%). The 4-year PFS by TP53 aberrant status is shown in Figure 1. The 4-year PFS for pts with del(17p)/TP53 mutation (n=27) is 90.9% and for pts without del(17p)/TP53 mutation (n=93) is 95.5%. None of the aforementioned pt/disease characteristics were associated with PFS. Of the 77 pts who were BM U-MRD at the end of cycle 24 of the combination, 73 discontinued all therapy, 4 pts continued IBR per treating physician discretion. Among these 77 pts, with a median time of 23.9 months post Cycle 24, 11 pts had recurrence of blood MRD (defined as MRD ≥0.01% in 2 consecutive visits). Of the 11 pts with MRD recurrence, 10 are being monitored without any active therapy for CLL and without clinical disease progression; 1 pt had disease progression after 22 months of treatment-free interval and is currently receiving acalabrutinib. There were 24 pts who were BM MRD+ at the end of cycle 24 of the combination (low MRD+, n=23; high MRD+, n=1). The only pt with high-MRD+ at end of cycle 24 was noted to have Richter transformation at that time. The remaining 23 pts (all low MRD+ in BM, range 0.01-0.95%) continued IBR monotherapy. With a recent trial amendment, MRD+ pts after Cycle 24 could get 12 additional cycles of VEN; 18/23 pts have resumed VEN. 11/18 (61%) pts achieved U-MRD remission during the third year of combined therapy. Conclusions: We report long term follow-up of combined IBR and VEN in first-line CLL (n=120) with a 4-year PFS of 94.5%. MRD responses and PFS were independent of baseline pt/disease characteristics. Continuation of combined therapy among marrow MRD+ pts during the second and the third year led to achievement of U-MRD in a subset of pts. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Residual Disease Kinetics Among Patients with High-Risk Factors Treated with First-Line Fixed-Duration Ibrutinib Plus Venetoclax (Ibr+Ven) Versus Chlorambucil Plus Obinutuzumab (Clb+O): The Glow Study

Background: In the GLOW study (NCT03462719), fixed-duration Ibr+Ven demonstrated superior progression-free survival (PFS), deeper, better sustained undetectable minimal residual disease (uMRD) responses, and fewer patients (pts) requiring subsequent anti-cancer treatment versus Clb+O in older and/or comorbid pts with previously untreated chronic lymphocytic leukemia (CLL; Kater AP, et al. NEJM Evidence. 2022). Unmutated IGHV (uIGHV) and TP53 mutations are risk factors associated with worse outcomes for both chemoimmunotherapy and venetoclax plus anti-CD20 therapies for CLL. Here we investigate MRD kinetics and outcomes of Ibr+Ven in GLOW according to these risk factors. Methods: Pts aged ≥ 65 years or 18 to 64 years with cumulative illness rating scale score > 6 or creatinine clearance < 70 mL/min were enrolled and randomized 1:1 to Ibr+Ven (3 cycles of Ibr lead-in, followed by 12 cycles of Ibr+Ven) or 6 cycles of Clb+O, with a cycle defined as 28 days. Pts with del(17p) or known TP53 mutations at screening were excluded, and central evaluation of TP53 mutational status was performed during the study. The primary end point was PFS by independent review committee. Among pts with partial response or better, MRD in peripheral blood was evaluated using next-generation sequencing via clonoSEQ on-treatment and at 3-6 month intervals post-treatment. uMRD results are reported in peripheral blood (PB) at < 10-4 unless otherwise noted. Since the primary analysis, a post hoc retrospective reclassification of the IGHV status of baseline samples was conducted to reduce the number of unknowns. We used clonoSEQ data as part of CLL clonal testing (Adaptive Biotechnologies, Seattle, WA). Results: There were 106 pts randomized to Ibr+Ven and 105 to Clb+O. In the Ibr+Ven arm, uMRD rates increased from 46.2% after 6 cycles of the combination to 54.7% at 3 months after end of treatment (EOT+3), demonstrating that the majority of disease clearance in the PB occurred early, during the first 6 months of combination treatment. Post-treatment, 77.6% (45/58) of pts in the Ibr+Ven arm sustained their uMRD status from EOT+3 to EOT+18, compared with 12.2% (5/41) in the Clb+O arm. In the Ibr+Ven arm, 17/24 patients with intermediate MRD ≥ 10-4 to < 10-2 at EOT+3 did not worsen through EOT+18. Among pts with detectable MRD (≥ 10-4) at EOT+3, 6.5% (2/31) clinically progressed by EOT+18 in the Ibr+Ven arm versus 68.1% (32/47) in the Clb+O arm. After reclassification of baseline samples, uIGHV / mutated IGHV (mIGHV) / unknown status was 63.2%/30.2%/6.6% in the Ibr+Ven arm and 54.3%/33.3%/12.4% in the Clb+O arm. In the Ibr+Ven arm, rates of uMRD after 6 cycles of combination treatment and at EOT+3, respectively, were 52.2% and 59.7% in pts with uIGHV and 31.3% and 40.6% in pts with mIGHV (Fig A). On-treatment MRD kinetics differed by IGHV status in the Ibr+Ven arm, with uMRD achieved at a higher rate and earlier in pts with uIGHV. In the Ibr+Ven arm, uMRD was sustained post-treatment (from EOT+3 and EOT+18) in 80.0% (32/40) of pts with uIGHV and 76.9% (10/13) of pts with mIGHV. Among pts with detectable MRD (≥ 10-4) at EOT+3, 2/16 with uIGHV and 0/14 with mIGHV had clinically progressed by EOT+18 in the Ibr+Ven arm; corresponding rates were 83.3% (25/30) and 42.9% (6/14) in the Clb+O arm. Five of 7 pts with TP53-mutated CLL achieved uMRD at EOT+3 in the Ibr+Ven arm; TP53 variant allele frequencies ranged between 5.9% and 29.6% for these 5 pts and all maintained uMRD through EOT+18. With a median study follow-up of 34.1 months, PFS rates after IGHV reclassification were well sustained post-treatment regardless of IGHV status in the Ibr+Ven arm, while uIGHV pts in the Clb+O arm relapsed more quickly (Fig B). PFS, overall survival, and subgroup analyses with longer study follow-up will be presented. Conclusion: All-oral, once-daily, fixed-duration Ibr+Ven achieved uMRD responses that were better sustained than Clb+O during the first 18 months post-treatment. Notably, with Ibr+Ven, uMRD rates were higher and achieved earlier in pts with uIGHV CLL versus mIGHV CLL, while uMRD was similarly sustained post-treatment irrespective of IGHV status. Clinical progressions in the first 18 months post-treatment with Ibr+Ven were uncommon even among pts with detectable MRD ≥ 10-4. MRD kinetics and sustained responses demonstrate strong efficacy of the fixed-duration Ibr+Ven combination in older pts with high-risk genomic features. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Lisaftoclax (APG-2575) Safety and Activity As Monotherapy or Combined with Acalabrutinib or Rituximab in Patients (pts) with Treatment-Naïve, Relapsed or Refractory Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma (R/R CLL/SLL): Initial Data from a Phase 2 Global Study

Introduction Lisaftoclax, a specific BCL-2 inhibitor, is active in pts with R/R CLL/SLL, including pts whose disease harbored del(17p) and had progressive disease (PD) after Bruton tyrosine kinase inhibitor (BTKi) therapy. This is the first report of lisaftoclax combined with acalabrutinib or rituximab in pts with CLL/SLL (NCT04215809). Methods Pts with R/R CLL/SLL were treated daily with oral lisaftoclax (400, 600, and 800 mg) alone or combined with continuous acalabrutinib or rituximab for 6 cycles of 28-day cycles. Primary objectives were to determine recommended phase 2 dose (RP2D), safety, and efficacy, including overall response rates (ORRs) of lisaftoclax alone and combined with acalabrutinib or rituximab. Pts underwent lisaftoclax daily ramp-up over 4 to 6 days with monitoring of tumor lysis syndrome (TLS) as follows: Day 1 (D1) 20 mg; D2 50 mg; D3 100 mg; D4 200 mg; and D5 400 mg. Dose ramp-up was followed by Cycle 1 D1 of lisaftoclax target doses of 400, 600 or 800 mg. Pts in the combination groups completed ramp-up as well as an additional 7 days of lead-in of lisaftoclax at the target dose, before acalabrutinib or rituximab was added on C1D8, and then treated until PD or unacceptable toxicity was observed. Results As of July 4, 2022, 141 pts were enrolled. Median (range) age was 62 (18-80) years; 98 (70%) were male; ECOG score was 0-1 in 125 (89%) and 2 in 15 (11%). Median number of prior therapies was 2 (1-15). Seventeen (12%) pts had progressed on BTKi (n = 15) and/or after venetoclax (n = 3) therapy. β-2 microglobulin levels > 3.5 mg/L were observed in 94 (67%) pts and lymphadenopathy ≥ 5 cm in 51 (36%). In the combination cohorts (n = 95), TP53 mutation or del(17p) was seen in 39 (41%) pts, del(11q) in 27 (28%), unmutated IGHV in 36 (38%), mutated IGHV in 14 (15%), and 47% were unknown. Median exposure to lisaftoclax was 10.0 (0-30) cycles, including 16.5 in the lisaftoclax monotherapy group and 9.0 (1-15) in the rituximab and 7.0 (0-18) in the acalabrutinib combination cohorts. Three (2%) pts with bulky disease met the Cairo-Bishop and Howard criteria for TLS (2 clinical/1 laboratory). Clinical TLS pertained to 1 pt with anuria after first 600 mg dose and 1 pt with grade 1 creatinine increase after second 600 mg dose; both pts fully recovered. A total of 6 pts with bulky disease had transient phosphate levels > 3 mmol/L and/or AST levels > 150 u/L associated with rapid decline in lymphocyte count. Phosphate ≥ 3 mmol/L was managed using binders and/or delayed dose increases. No TLS was observed when acalabrutinib or rituximab was added to lisaftoclax on C1D8. Common (> 5%) any-grade AEs in all cohorts were: neutropenia (30% [26% grade 3/4]); COVID-19 infection (26%); anemia (24% [12% grade 3/4]), diarrhea (20%); thrombocytopenia (17% [5% grade 3/4]), hyperuricemia or pyrexia (9% each); nausea, headache, or fatigue (8% each); increased AST levels (7%); hyperphosphatemia (6%); and increased creatinine (6%). First onset of grade ≥ 3 cytopenias occurred during ramp-up or C1 and rarely after C2 (n = 3 [2%]). Grade ≥ 3 neutropenia was manageable with growth factor support in 13% of pts. No discontinuations were due to lisaftoclax alone or combined with the other agents. Nineteen pts discontinued due to PD (13%), of whom 18 were in the monotherapy group; 4 (3%) pts withdrew consent; 2 (1.4%) had a second primary malignancy; 2 (1.4%) an infection; and 10 (7%) died-8 due to COVID-19 infections as well as 1 multiorgan failure and 1 unknown cause, both unrelated to therapy. No dose-limiting toxicities were observed. Lisaftoclax 600 mg QD was determined as the combination therapy RP2D. No drug-drug interaction was observed in either combination group. Rapid normalization of absolute lymphocyte counts occurred in 56% of pts at the end of daily ramp-up, 58% at the end of C1, and 65% at the end of C2. A total of 43 (65%) ORRs (per 2018 iwCLL criteria) occurred in the monotherapy group, and 53 (98%) and 23 (87%) in the acalabrutinib and rituximab cohorts, respectively. Collection of complete response rate and undetectable minimal residual disease data is in progress. Conclusions The RP2D of lisaftoclax was 600 mg daily. Initiated with a daily dose ramp-up, lisaftoclax alone or combined with acalabrutinib or rituximab had a manageable safety profile and was active in pts with treatment-naïve or R/R CLL/SLL.

Real-World Outcomes of Second-Line Chronic Lymphocytic Leukemia Treatments: Retrospective Analysis of the Brazilian Registry of CLL

Introduction: Major advances in the treatment of relapsed-refractory (RR) chronic lymphocytic leukemia (CLL) patients were observed in the last decade with the adoption of targeted agents. While a shift away from chemotherapy is expected, the impact of delayed or unequal access to targeted agents in low- and middle-income countries needs to be uncovered through real-world data. Objective: To assess the clinical outcomes of second-line treatment in RR CLL patients included in the Brazilian Registry of CLL (BRCLL). Patients and Methods: This is an observational study of second-line CLL treatments started between January 2006 and December 2021. BRCLL is a prospective non-interventional data collection tool. All participant centers registered their CLL patients online, after study approval at each center's ethical review board. Diagnosis and staging of included CLL patients were performed in accordance with recommendations from the International Workshop on Chronic Lymphocytic Leukemia (IWCLL). Results: Four hundred and forty-four CLL patients in second-line were included. Median age at start of second-line treatment was 66 years (range: 23-93), and 264 were male (59%). At CLL diagnosis, Binet staging was A in 139 patients (36%), B in 139 (36%), and C in 107 (28%). High beta-2-microglobulin levels at diagnosis were found in 58%, and unmutated IGHV was observed in 61% of patients. At diagnosis, FISH was performed in 166 patients (37%), of which 33 patients had del(17p) (20%). The most commonly prescribed second-line treatments were: FC (+/- R) in 160 patients (36%); chlorambucil (+/- R) in 109 (25%); ibrutinib in 63 (14%); CHOP/CVP (+/- R) in 62 (14%); monoclonal antibodies (+/- steroids) in 33 (7%); allogeneic stem cell transplantation in 9 (2%) and venetoclax in 8 (2%). Forty patients (9%) were treated in clinical trials. Median follow-up after second-line treatment was 34 months (range: 3-176). Median time-to-next treatment (TTNT) was 28 months. TTNT was statistically longer in patients who received second-line with ibrutinib or venetoclax in comparison with FC or chlorambucil +/- anti-CD20 (not reached versus 29 months, p<0.0001) or those who received other regimens (CHOP or CVP +/- anti-CD20, monoclonal antibodies +/- steroids - 12 months, p<0.0001). Higher 3-year treatment-free survival (TFS) was also observed with ibrutinib or venetoclax (69% versus 41% and 23%, respectively, p<0.0001). Among patients included in clinical trials, 3-year TFS was also higher (70% versus 38%, p<0.0001). TFS for patients receiving allogeneic stem cell transplantation was 86% at 3 years. Overall survival (OS) probability at 3 years was 71%. OS was significantly shorter in those who received other regimens (CHOP/CVP-like or monoclonal antibodies +/- steroids - 53%), in comparison with those who received ibrutinib or venetoclax (80%, p<0.0001), or FC/chlorambucil-based chemotherapy (69%, p=0.01). Conclusion: Over the reported period, second-line CLL treatments in Brazil were mostly chemotherapy- or chemoimmunotherapy-based, with unfavorable outcomes associated with CHOP/CVP-like regimens or monoclonal antibodies +/- steroids. While the adoption of targeted therapies was associated with longer TTNT and OS, access to these agents is still very limited in the public setting.

Outcomes of Therapies and Resistance Mutations Following Non-Covalent Bruton's Tyrosine Kinase Inhibitor Treatment for Patients with Chronic Lymphocytic Leukemia and Richter Transformation

Background: Non-covalent Bruton's Tyrosine Kinase inhibitors (ncBTKi) have shown excellent clinical activity for patients (pts) with relapsed and/or refractory chronic lymphocytic leukemia (CLL) and Richter Transformation (RT). However, some pts treated with ncBTKi develop progressive disease (PD). In addition, acquired BTK mutations (mut) at the time of PD on ncBTKi were recently described, although the frequency at which these mut occur has not been reported. Currently, data regarding treatment sequencing post ncBTKi are lacking but are critical to guide further treatment selection. Methods: We conducted a retrospective, multicenter study of pts treated with any ncBTKi for CLL or RT who have discontinued ncBTKi for any reason. Using a standardized template we collected: pt and disease characteristics (including prior therapies, cytogenetic/molecular characteristics), demographics, clinical response to ncBTKi and subsequent therapies, and survival. Data on 2 lines of therapies (LOT) following ncBTKi were collected for each pt. Primary endpoint was overall response rate (ORR) for therapies following ncBTKi. Progression free survival (PFS) was estimated using the Kaplan Meier method. We also collected next generation sequencing (NGS) data for CLL pts who discontinued ncBTKi. Analyses were performed using STATA 17.0. Results: We identified 63 pts (48 CLL, 15 RT) treated with who then discontinued ncBTKi. Baseline characteristics at ncBTKi start are presented in Table 1. Median number of prior therapies was 4 (1-10), and most pts received prior covalent BTKi (93.7%) and venetoclax (57.1%). At ncBTKi start, 84.8% of patients had unmutated IGHV, 48.8% had a TP53 mut and 37.0% had a complex karyotype. ORR to ncBTKi was 58.8% for the CLL cohort (PR 54.4%, PR-L 4.4%) and 46.7% for the RT cohort (CR 6.7%, PR 40%). Median duration of ncBTKi exposure prior to discontinuation was 9 (1-27) and 4 (1-12) months for CLL and RT, respectively. Overall, 73.7% of the combined cohort progressed on ncBTKi. Specific reasons for ncBTKi discontinuation included: CLL PD (n=26, 41.2%), PD of existing RT (n=7), death not secondary to PD or toxicity (n=6), other reason (n=6), stem cell transplant (SCT, n=5), toxicity (n=4), PD of CLL to RT (n=4), MD/pt preference (n=2), CAR T (n=2), and sudden death on therapy (n=1). Following ncBTKi, 76.2% of pts (n=48) received another LOT. Therapies and responses are presented in Table 1. Common treatment strategies were: chemo+/-immunotherapy (CIT) (n=16, ORR 18.8%), CD19-directed CAR T-cell therapy (n=7, ORR 85.7%), allogeneic SCT (n=6, ORR 83.3%), and venetoclax-based therapy (n=10, ORR 70.0%). 27.3% of therapies administered post ncBTKi were administered on a clinical trial. For CLL pts, median PFS for first LOT following ncBTKi was 14 months (n=25 pts, Figure 1). For the RT cohort, the median PFS for the first LOT following ncBTKi discontinuation was 6 months (median follow-up 2.5 months). Importantly, median PFS for venetoclax following ncBTKi discontinuation for CLL pts was 14 months (8 pts, 87.5% venetoclax-naive, median follow-up 10.5 months). 49.2% of the overall cohort has died, with 58.6% of deaths due to CLL or RT (n=17 of 29 pts with available data). 15 CLL pts who discontinued ncBTKi for PD had end of treatment NGS data available. For these pts, at the start of ncBTKi, BTKC481 mut and PLCG2 mut were present in 38.5% and 33%, respectively. At end of ncBTKi treatment, novel (not C481) BTK mut were identified in 9 of 15 pts (60.0%). These included mut in BTKL528W (n=6), BTKV416L (n=2) and BTKT474I (n=2); 1 pt had mut in both BTKT474I and BTKL528W. Additionally, 4 pts had pre-existing mut in PLCG2 that persisted at PD. Overall, 11 of 15 (73.3%) of CLL pts had a novel BTK mut and/or a persistent PLCG2 mut at PD on ncBTKi. Conclusions: We report results from the first series of CLL and RT pts following ncBTKi discontinuation. CIT for RT and CLL yielded poor outcomes, while CAR T-cell therapy and allogeneic SCT had high ORR warranting further investigation. Most importantly, venetoclax has clinical activity (high ORR, durable PFS) for CLL pts following ncBTKi discontinuation suggesting CLL pts can stay within the BTKi class prior to switching to venetoclax. In addition, at PD 73% of pts had a novel BTK mut and/or the persistence of a PLCG2 mut conferring resistance to ncBTKis. Overall, these results highlight an unmet need for novel therapeutic strategies for pts who require treatment following ncBTKi. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Updated Results from a Phase I/II Study of Duvelisib and Venetoclax in Patients with Relapsed or Refractory (R/R) Chronic Lymphocytic Leukemia (CLL) or Richter's Syndrome (RS)

Background While venetoclax (VEN) in combination with rituximab is an effective combination for patients (pts) with R/R CLL, it requires 2 years (yrs) of treatment (tx) and intravenous infusions. Duvelisib (DUV) is an oral PI3K-δ/γ inhibitor (PI3Ki) approved for R/R CLL/SLL after 2 prior therapies, and preclinical data support the potential for synergy both in CLL (Patel et al., 2017) and in RS PDX models (Iannello et al., 2019). This ongoing phase I/II study is investigating an all-oral, MRD-guided, time-limited regimen of DUV + VEN. Here, we report updated outcomes, now with nearly 2 yrs median follow-up. Methods In this ongoing investigator-sponsored trial (NCT03534323), primary endpoints were DLTs, MTD, RP2D (phase 1) and best CR rate (phase 2). Key eligibility criteria for CLL pts: requiring tx by iwCLL criteria, ≥1 prior tx but no prior DUV or VEN, ECOG PS ≤2. For RS pts there was no restriction on # of prior tx, though no VEN was allowed within 1 yr. Pts receive a maximum of 12 cycles of combination DUV + VEN. Tx begins with a 7-day lead-in of DUV 25mg BID, and VEN initiation occurs on day 8. In phase 1, VEN was started at 10mg or 20mg inpatient (inpt) with weekly ramp-up outpatient (outpt) to 50mg, and then to a maximum dose of 100mg, 200mg, or 400mg using a 3+3 design. In phase 2, VEN is initiated at 10mg (outpt) or 20mg (inpt) with weekly ramp-up to 400mg daily. Pts with RS can undergo accelerated VEN ramp-up to 400mg over 5 days (inpt). After 12 cycles, pts with undetectable bone marrow MRD (BM-uMRD) can discontinue tx, with an option to reinitiate VEN at progression, and pts with detectable MRD continue VEN. Assessments: toxicities by CTCAE v5, efficacy by 2008 iwCLL criteria, MRD by central 8-color flow (10-4 sensitivity). Research funding and DUV were provided by Secura Bio. Results As of July 13, 2022, 43 pts were enrolled (n=35 CLL and n=8 RS). Median age: 69 yrs (range 50-79); 70% male. 70% unmutated IGHV. In all patients, 42% were TP53-aberrant (del(17p) or TP53 mut); 9% del(11q); 33% complex karyotype (≥ 3 abnormalities); 23% NOTCH1 mut. Median prior tx: 2 (range 1-6). 42% with prior BTKi tx (all ibrutinib). The RP2D of VEN in combination with DUV was 400mg daily. In the total population of 43 pts, all-grade all-causality heme tox included: neutropenia (64%; 57% Gr3/4), thrombocytopenia (43%; 19% Gr3/4), anemia (33%, 5% Gr3). Notable non-heme tox ≥ 20% included: diarrhea (40%; 7% Gr 3), nausea (40%, 2% Gr3), fatigue (40%, all Gr1/2), hypertension (36%, 7% Gr3), increased alkaline phosphatase (36%, all Gr1/2), headache (26%, all Gr1/2), increased AST/ALT (24%; 7% Gr3), and cough (26%, all Gr1/2). Other notable SAEs ≥ 5%: increased bilirubin (12%, 5% Gr3/4), severe infection (9% Gr3, 1 pt with Gr5 COVID-19 pneumonia). 3 pts had laboratory evidence of tumor lysis syndrome (TLS); 1 pt had clinical TLS with acute kidney injury after the 20 mg VEN dose during ramp-up that fully resolved, and the pt successfully resumed VEN monotherapy. One pt developed a Gr4 gastric perforation while on high-dose steroids to manage diarrhea and discontinued study tx. One pt with RS had Gr5 hepatic failure in the setting of biopsy-proven RS liver involvement. The median number of cycles was 13 (range 1-44). The best ORR in the pts with CLL (n=35) was 69% (43% CR/CRi, 26% PR; Figure 1A). 31% of pts with CLL achieved PB-uMRD and 31% BM-uMRD (Figure 1A). 9/35 pts (26%) achieved CR/CRi with BM-uMRD after 1 year of DUV+VEN and electively discontinued therapy in remission, including 4 pts with del(17p). In the pts with RS (n=8), 3 achieved a CR and 1 achieved a PR. In the 16 CLL pts with TP53-aberrancy, the best ORR was 50% (CR 44%, PR 6%). In 15 CLL pts with prior BTKi tx, the best ORR was 53% (CR/CRi 40%, PR 13%). Eleven pts remain on tx. Reasons for tx discontinuation include: achievement of BM-uMRD (n=12 CLL), electively moving on to allogeneic transplant (n=2 CLL, n=1 RS), PD (n=3 CLL, n=6 RS), unacceptable tox (n=4 CLL, n=1 RS), death due to COVID-19 pneumonia (n=1 CLL). The 2-year PFS for pts with CLL was 78% (95% CI: 63-96; Figure 1B) and the 2-year OS was 90% (95% CI: 80-100). Conclusion A time-limited, all oral regimen DUV + VEN is active in R/R CLL and RS, including in high-risk pts post-BTKi. Immune-mediated and infectious toxicities were observed, but were manageable for most patients. Our data support continued exploration of DUV + VEN in pts with R/R CLL and RS. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Efficacy and Safety of Nemtabrutinib, a Wild-Type and C481S-Mutated Bruton Tyrosine Kinase Inhibitor for B-Cell Malignancies: Updated Analysis of the Open-Label Phase 1/2 Dose-Expansion Bellwave-001 Study

Background: Bruton tyrosine kinase inhibitors (BTKis) have transformed the treatment landscapes of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and certain B-cell neoplasms. However, the most common mechanism of resistance is due to mutations to BTK at the cysteine binding site (C481). Nemtabrutinib (MK-1026, formerly ARQ-531) is a noncovalent, potent inhibitor of both wild-type and ibrutinib-resistant C481S-mutated BTK. Initial results from the phase 1/2 BELLWAVE-001 study (NCT03162536) showed nemtabrutinib had a manageable safety profile and promising antitumor activity in heavily pretreated patients (pts) with relapsed or refractory (R/R) CLL/SLL, including pts whose disease progressed after prior covalent BTKis (Woyach et al. Blood. 2021;138:392). We present updated efficacy for all pts with CLL/SLL treated with nemtabrutinib 65 mg and safety for all pts with hematological malignancies who were treated with nemtabrutinib at the 65-mg dose. Methods: In this open-label, single-arm, phase 1/2 study, 9 expansion cohorts were initiated after determination of the preliminary nemtabrutinib recommended phase 2 dose (RP2D). Eligible pts with CLL/SLL were enrolled in cohort A (R/R CLL/SLL, with ≥2 prior therapies, including covalent BTKis, with documented C481 mutation), cohort B (R/R CLL/SLL with ≥2 prior therapies, intolerant to a BTKi, without C481 mutation), a dose-expansion group, or cohort I (food effect). Primary end points were ORR (per 2018 IWCLL criteria, by investigator), safety, and RP2D for pts with CLL/SLL. Secondary end points were DOR (including partial response [PR] with lymphocytosis), PFS, and safety. Efficacy analysis included CLL/SLL pts treated with nemtabrutinib 65-mg once-daily dose and safety included all pts with hematological malignancies who were treated with the nemtabrutinib 65-mg dose. Results: A total of 112 pts were enrolled and were treated with nemtabrutinib 65 mg once daily: 57 had CLL/SLL, 46 had B-cell non-Hodgkin lymphoma (NHL), 6 had Waldenstrom's macroglobulinemia, and 3 had a diagnosis of "other.” Among the 57 pts with CLL/SLL enrolled and treated with nemtabrutinib 65 mg (cohort A, n = 25; cohort B, n = 10; dose escalation, n = 13; cohort I, n = 9); median age was 66.0 years; 16 pts (28%) were female, and 50 (88%) had ECOG PS ≤1. Median (range) number of prior therapies was 4 (1-18); 54 pts (95%) had prior BTKi therapy; 24 (42%) had prior BTKi and BCL2i therapy. In addition, 36 pts (63%) had C481S-mutated BTK; 18 (32%) had TP53 mutation; 19 (33%) had del(17p); and 30 (53%) had unmutated IGHV. Of pts with CLL/SLL, 39 (68%) discontinued, most commonly because of clinical disease progression [PD] and "other” causes (10 [18%] each); 8 (14%) discontinued owing to adverse events (AEs). Among the 24 pts with CLL/SLL who received prior BTKis and BCL-2is, 19 (33%) discontinued, most commonly because of clinical PD and other causes (6 [11%] each) and AEs (4 [7%]). At data cutoff (April 08, 2022), median (range) follow-up for pts with CLL/SLL was 8.1 months (0.1-38.8); 32 pts had objective response (ORR, 56% [95% CI, 42-69]; complete response, 2; PR, 15; PR with residual lymphocytosis, 15). Among the 32 pts who responded, median DOR was 24.4 months (95% CI, 13.9-not evaluable [NE]); median PFS was 26.3 months (95% CI, 10.1-NE). Efficacy by key subgroups is presented in the table. Among all pts with B-cell malignancies treated with nemtabrutinib at the 65-mg dose (N = 112) included in the safety analysis, 82 (73%) had any-grade treatment-related AEs (TRAEs), most common (≥10%) were dysgeusia (21%); decreased neutrophils (20%); fatigue (13%); nausea and decreased platelets (12%, each); and diarrhea and hypertension (10%, each). Grade 3 or 4 TRAEs occurred in 45 pts (40%); most common (≥5%) were decreased neutrophils (17%) and decreased platelets and lymphocytosis (5%, each). Treatment-related discontinuations occurred in 15 pts (13%). No deaths were attributed to treatment. Conclusion: Nemtabrutinib 65 mg continued to show promising and durable antitumor activity with a manageable safety profile in a highly relapsed/refractory population who had prior therapy with novel agents. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Treatment Patterns and Outcomes of Patients with Chronic Lymphocytic Leukemia with TP53 Mutations

Background: Aberration of the TP53 gene in chronic lymphocytic leukemia (CLL) is a well-established marker of poor prognosis and a predictor of chemorefractory disease. Identification of a TP53 gene mutation is clinically useful in determining which patients may benefit from small-molecule inhibitors such as Bruton tyrosine kinase (BTKi) and BCL2 inhibitors (BCL2i). However, the treatment patterns in routine practice and outcomes of patients harboring TP53 mutations in CLL is not well reported. We present a descriptive analysis of CLL patients treated at Mayo Clinic with TP53 mutations including their demographics, treatment patterns, and outcomes. Methods: Patients with CLL who had a TP53 mutation detected by Sanger sequencing between June 2014 and April 2021 at Mayo Clinic Rochester were identified from a hematopathology database. Patient demographics, clinical and pathologic characteristics, treatment, and follow-up information were abstracted from the Mayo Clinic CLL database and by chart review. Date of TP53 mutation test was baseline. Discrete variables were compared using Chi-square or Fisher's exact tests; continuous variables were compared using Kruskal-Wallis test. Overall survival (OS) was calculated from date of TP53 mutation test until date of death from any cause or last known date alive. Rates of Richter transformation (RT) by prior treatment exposure were estimated by cumulative incidence accounting for competing risk of death. Results: A total of 145 patients were identified; 70% were male, and the median age at diagnosis was 59 years (range: 36-92). At diagnosis, 15% of patients had Rai stage III-IV, 77% had unmutated IGHV, 38% had del17p, 92% had high or very high CLL-IPI, and 62% had ≥3 cytogenetic abnormalities (Table 1). A TP53 gene mutation was identified prior to any CLL treatment in 63 patients (43%, Group 1) and after at least one prior line of treatment in 82 patients (57%, Group 2). The median time from CLL diagnosis to the first detected TP53 mutation was 3 months in Group 1 and 96 months in Group 2. There was significant heterogeneity in types of TP53 mutations with the majority of variants (n=102) being unique to an individual. At the time of TP53 mutation detection, Group 2 patients more frequently had advanced Rai stage and unmutated IGHV status (Table 1). Del17p by FISH was present prior to or at time of TP53 mutation identification (+/- 3 months) in 54% of patients in Group 1 and 52% in Group 2. Group 1 had a median follow-up of 26 months (from TP53 mutation detection date); 46/63 patients had initiated a first-line (1L) treatment (39 BTKi-based, 1 BCL2i-based, 2 BTKi+BCL2i-based, 4 chemoimmunotherapy [CIT]). In Group 2, the median number of prior lines of therapy was 2 (range 1-16). Prior treatment exposure included 38 (46%) CIT only, 41 (50%) BTKi-based ± CIT, and 3 (4%) BTKi-based + BCL2i-based ± CIT. Median follow-up was 21 months; 56/82 patients had initiated a new line of therapy (subsequent 1L). For 38 patients with prior CIT only exposure, 28 had subsequent 1L including 21 BTKi-based, 2 BCL2i-based, and 5 CIT. For 44 patients with prior BTKi exposure, 28 had subsequent 1L including 5 BTKi-based, 5 BCL2i-based, 9 BTKi+BCL2i-based, and 9 CIT. The median OS was not reached in Group 1 and was 40.6 months (95% CI 30.1-NE) in Group 2 (HR=0.21, 95% CI=0.10-0.45) (Figure 1). In Group 2, the median OS for patients with prior CIT only exposure was 55.5 (95% CI 30.1-NE) months and for patients with prior BTKi exposure was 33.3 (95% CI 14.7-NE) months (HR=0.59, 95% CI=0.31-1.12) (Figure 1). Three patients in Group 1 and 13 patients in Group 2 (3 prior CIT only, 10 prior BTKi) developed RT during the follow-up period; the cumulative incidence rates of RT at 2- and 5-year were 1.7% and 4.6%, respectively, in Group 1, and 10.8% and 21.0%, respectively, in Group 2. Conclusions: Regardless of prior treatment exposure, enrichment for high-risk features was present at time of TP53 mutation detection. Majority of patients were treated with novel agents after known TP53 mutations. OS after TP53 mutation was inferior in patients who had been previously treated, particularly those who had BTKi exposure already prior to TP53 mutation detection, compared to previously untreated patients. Future studies are needed to understand the characteristics of clonal evolution before and after treatment and the clinical impact of specific TP53 mutations. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Phase 1/2 Study of Acalabrutinib Monotherapy in Patients with Relapsed/Refractory Chronic Lymphocytic Leukemia: Final Results with >4 Years of Follow-up

Background: Treatment with Bruton tyrosine kinase (BTK) inhibitors has remarkably improved clinical outcomes for patients with chronic lymphocytic leukemia (CLL). Acalabrutinib is a highly selective, covalent BTK inhibitor approved for the treatment of CLL. Here we report the final analysis of the phase 1/2 study of acalabrutinib (multicenter, multicohort ACE-CL-001 study; NCT02029443) with median follow-up of 53 months in patients with relapsed/refractory (R/R) CLL/small lymphocytic lymphoma (SLL). Prior analyses were reported at median follow-up durations of 14 months (Byrd et al. N Engl J Med. 2016;374:323-32) and 41 months (Byrd et al. Blood. 2020;135:1204-13). Methods: Adult patients with CLL or SLL who had received ≥1 prior treatment and had an Eastern Cooperative Oncology Group performance status (ECOG PS) ≤2 were included in the R/R cohort of the study. In the dose-escalation portion of the study, patients were enrolled into dose cohorts at acalabrutinib dosages of 100, 175, 250, and 400 mg once daily (QD) and 100 mg or 200 mg twice daily (BID). In the phase 2 portion of the study, patients received oral acalabrutinib 100 mg BID or 200 mg QD, later switching to 100 mg BID, until progressive disease or unacceptable toxicity occurred. The primary study endpoint was safety. Secondary endpoints included overall response rate (ORR), duration of response (DOR), and progression-free-survival (PFS), with post hoc analysis of event-free survival (EFS). Response rates were based on the iwCLL 2008 criteria with modification for lymphocytosis. Results: In total, 134 patients with R/R CLL/SLL received ≥1 dose of acalabrutinib (dosing information was previously reported; Byrd et al. Blood. 2020;135:1204-13). Median age was 66 years, and 97% of patients had ECOG PS ≤1, 73% unmutated IGHV, 27% del(17p), 20% del(11q), and 35% complex karyotype. The median number of prior therapies was 2 (range 1-13). At the final data cutoff date of July 15, 2021, at a median follow-up of 52.6 (range 0.56-88.8) months, 31% of patients remained on acalabrutinib. The most common reasons for discontinuing treatment were progressive disease (37%) and adverse events (AEs; 15%). The most commonly reported AEs were consistent with those reported in the previous update (Table 1); no new AEs emerged with longer term follow-up. AEs leading to discontinuation that occurred in >1 patient were pneumonia (5 patients), anemia, neutropenia, diarrhea, and thrombocytopenia (2 patients each). Events of clinical interest (all grades; grade ≥3, respectively) included atrial fibrillation/flutter (9%; 3%), hypertension (23%; 11%), infection (88%; 33%), bleeding events (71%; 6%), major bleeding events (8%; 6%), and ventricular tachyarrhythmias (2%, 1%). No cases of sudden death were reported. The ORR (partial response or better) was 90% (95% confidence interval [CI] 84-95); 4% of patients had complete response and 87% partial response (PR). The median DOR was 60.1 months (range 2.7-81.0). The 66-month estimated DOR rate was 45% (95% CI 36-55). Responses were similar regardless of high-risk features, including unmutated IGHV (n=73/81; 90%), del(17p) (n=27/31; 87%), del(11q) (n=20/23; 87%), and complex karyotype (n=17/20; 85%). The median PFS was 66.1 months (range 0.4-87.8; Figure 1), and the median EFS was 53.8 months (range 44.1-66.1). The 72-month estimated PFS was 45% (95% CI 36-54) and the 72-month estimated EFS was 37% (95% CI 29-46). Reported EFS events overall included AEs (n=18/134, 13%), death (n=5/134, 4%), disease progression (n=54/134, 40%), and new anticancer therapy (n=3/134, 2%). Conclusions: The results of this final analysis confirm the earlier reports of acalabrutinib efficacy and were later confirmed by similar outcomes of response durability and long-term tolerability in the pivotal ASCEND phase 3 trial in patients with R/R CLL/SLL (Jurczak et al. J Clin Oncol. 2022;40[suppl 16]:7538). Reported AEs indicate a tolerable and consistent safety profile, with low rates of atrial fibrillation and major bleeding events with median follow-up of 53 months (up to 7.4 years). No new safety signals were identified. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Updated Results from a Multicenter, Phase 2 Study of Acalabrutinib, Venetoclax, Obinutuzumab (AVO) in a Population of Previously Untreated Patients with CLL Enriched for High-Risk Disease

Background While venetoclax (V) plus obinutuzumab (O) is a highly effective frontline CLL regimen, outcomes remain suboptimal for high-risk patients (pts). The efficacy of ibrutinib plus VO in such pts is encouraging, but cardiac and infectious toxicities (tox) are common. We hypothesized that a time-limited triplet with the more selective BTKi acalabrutinib (A) would be active and well-tolerated. We previously published results on an initial cohort unrestricted by genetic risk (Davids et al., 2021), and now report on a new cohort with enrollment restricted to high-risk pts, as well as longer follow-up on the initial cohort. Methods Treatment (tx)-naïve pts with CLL with any genetic risk profile were initially enrolled in this investigator-sponsored, phase 2 study (cohort 1), followed by a multi-center expansion restricted to previously untreated pts with TP53-aberrant CLL (cohort 2). A starts at 100 mg BID for 28 days, followed by 2 cycles of AO (O at standard dosing), and V starts on C4D1 at 20 mg, then 50 mg on C4D2, with weekly ramp-up thereafter to 400 mg QD (total 4 week V ramp-up). AVO continues C5-7 (6 total cycles of O), and AV continues C8-15. If the primary endpoint of undetectable bone marrow MRD (BM-uMRD) CR is reached at C16D1, pts can discontinue therapy (tx); all others continue AV through C24, with the option to discontinue if BM-uMRD at C25D1. Assessments: efficacy by 2018 iwCLL criteria, toxicities (tox) by CTCAE v5, MRD by central 8-color flow (10-4 sensitivity) and NGS clonoSEQ (up to 10-6 sensitivity, Adaptive). BH3 profiling work is ongoing, performed as previously described (Ryan J et al., 2016) on peripheral blood (PB) samples after 1 and 3 cycles. Association of BCL-2 dependence with clinical response was compared by an unpaired t-test. Results As of 13 July 2022, 68 pts were enrolled (cohort 1 all-comers: n=37, cohort 2 TP53-aberrant: n=31) in this ongoing study (NCT03580928), with median follow-up of 35 mos (range 2-45). In all 68 pts, median age 63 yrs (range 36-80); 25% ≥70 yrs; 66% male; 60% TP53-aberrant (del(17p) or mut); 24% complex karyotype (≥3 abnormalities); 74% unmutated IGHV. Of the 56 pts evaluable to date at C16D1, 43% (24/56) achieved the primary endpoint BM-uMRD CR. The best ORR is 98% (48% CR, 50% PR). At C16D1, MRD by flow: 86% PB-uMRD, 86% BM-uMRD (Fig 1A). In a subset of 49 pts with available samples, 59% were PB-uMRD by NGS at 10-5 sensitivity (at 10-6, 59% of pts had indeterminate results due to low cell counts). In the 29 pts with TP53-aberrant disease evaluable at C16D1, the best ORR is 100% (52% CR, 48% PR), and 45% (13/29) achieved BM-uMRD CR, MRD by flow: 86% PB-uMRD, 83% BM-uMRD (Fig 1A). There were no differences in response or MRD based on IGHV status. 79% (19/24) of pts in BM-uMRD CR electively discontinued tx after 15 cycles; median time off tx for these pts is 22.9 mos (range 1-30). 2 of the 19 pts who discontinued tx have had MRD only recurrence, and 1 had CLL disease progression; all 3 restarted tx with AV and achieved PR. 3 pts developed Richter's syndrome: 1 with DLBCL after 15 mos on study, and 2 with Hodgkin transformation (one 13 mos after completing study tx and one 12 mos into study tx; both achieved CR to Hodgkin-directed tx). 93% of all pts (63/68) remain progression-free. In all 68 pts, all-grade heme tox included: neutropenia (75%; 37% Gr3/4), thrombocytopenia (73%; 28% Gr3/4), anemia (49%, 3% Gr3). Non-heme tox: headache (78%, 1% Gr3), fatigue (76%, 1% Gr3), bruising (66%, all Gr1/2), nausea (49%, all Gr1/2), diarrhea (40%, 4% Gr3), infusion-related reaction (30%, 4% Gr3), hypertension (27%; 9% Gr3), increased ALT (27%, 1% Gr3), arthralgia (25%, all Gr1), and infection (6% Gr3; 1 case of Gr5 COVID-19 pneumonia). 2.9% (2/68) pts had afib. 14 pts (21%) required dose-reduction of either only A (4%), only V (9%), or both drugs (7%). BH3 profiling is ongoing, and initial data suggest that pts who later went on to achieve CR may have a greater increase in BCL-2 dependence at C4D1 than pts who achieved PR as best response (p=0.05, Fig 1B). Conclusion AVO is a highly active, well-tolerated triplet in a frontline CLL population enriched for high-risk disease, with 83% of TP53-aberrant pts achieving BM-uMRD after 15 mos of tx. Responses are durable, with 93% PFS in all pts at a median follow-up of nearly 3 yrs. Low rates of cardiac and infectious tox were observed. Our data support continued investigation of the MRD-guided, time-limited AVO triplet. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Efficacy of Pirtobrutinib in Covalent BTK-Inhibitor Pre-Treated Relapsed / Refractory CLL/SLL: Additional Patients and Extended Follow-up from the Phase 1/2 BRUIN Study

Background: Covalent Bruton tyrosine kinase inhibitors (BTKi) have transformed the treatment landscape of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Despite the efficacy of covalent BTKi, treatment failure often occurs through development of resistance or intolerance. Pirtobrutinib, a highly selective, non-covalent (reversible) BTKi, inhibits both wildtype and C481-mutant BTK with equal low nM potency, and has favorable oral pharmacology that enables continuous BTK inhibition throughout the dosing interval regardless of intrinsic rate of BTK turnover. Pirtobrutinib is well tolerated and has demonstrated promising efficacy in patients (pts) with poor-prognosis B-cell malignancies following prior therapy, including prior covalent BTKi (Mato et al. Lancet, 2021). Here, we report updated CLL/SLL results from the BRUIN study (NCT03740529). Methods: Pts with previously treated B-cell malignancies, including CLL/SLL, were eligible for treatment with pirtobrutinib monotherapy in either the dose escalation or expansion portion of the multicenter BRUIN study. Key endpoints included overall response rate (ORR) per 2018 iwCLL response criteria, progression-free survival (PFS), and safety. The response evaluable cohort consisted of all CLL/SLL pts enrolled to either phase 1 or 2 who had received a prior covalent BTKi containing regimen and had undergone their first response assessment or discontinued therapy. The safety cohort consisted of all pts with B-cell malignancies who received at least one dose of pirtobrutinib monotherapy (n=725). A data cut of 31 January 2022 was utilized. Results: Among the 276 pts with CLL/SLL who had received a prior BTKi, median age was 69 (range 36-88) years and the median number of prior therapies was 3 (range 1-11). Additional prior therapies included anti-CD20 antibody (89%), chemotherapy (80%), BCL2 inhibitor (44%), PI3K inhibitor (24%), CAR-T cell therapy (6%), and stem cell transplantation (2%). High-risk features were frequent: del(17p) in 29% (58/197), mutated TP53 in 40% (91/230), and unmutated IGHV in 85% (188/220). The majority of pts (n=206, 75%) discontinued prior BTKi therapy due to disease progression. Overall, 84% (n=232) received the recommended phase 2 dose of 200 mg once daily as starting dose. In this group of heavily pretreated relapsed/refractory CLL/SLL patients, including all with prior BTKi use, the ORR by investigator assessment was 74% (95% CI, 68-79) (Table) including 3 complete responses (1%), 174 partial responses (PR; 64%), 23 PRs with lymphocytosis (PR-L; 8%), and 1 nodular PR (<1%). At a median follow up time of 13.9 months, the median PFS was 19.4 months (95% CI, 16.6-22.3) (Figure). The 12-month and 18-month estimated PFS rates were 68% (95% CI, 62-74) and 54% (95% CI, 46-61), respectively. The ORR and PFS across various patient subgroups are depicted in the Table. In the safety cohort of all pirtobrutinib treated pts with B-cell malignancies (n=725), the most common TEAEs, regardless of attribution, were fatigue (26%, n=191), diarrhea (22%, n=160), and contusion (19%, n=138). The most frequent Grade ≥3 TEAE was neutropenia (20%, n=143). Low rates of Grade ≥3 TEAEs of hypertension (3%, n=20), hemorrhage (2%, n=16), and atrial fibrillation/flutter (1%, n=7) were observed. Overall, 15 (2%) pts discontinued due to a treatment-related AE. Conclusion: In this updated analysis with additional pts and extended follow-up, pirtobrutinib continues to demonstrate promising and durable efficacy in heavily pre-treated R/R CLL/SLL pts who have been treated with a prior covalent BTKi, regardless of prior therapy, reason for prior BTKi discontinuation, age, high-risk TP53 mutations, C481 mutational status, and/or del(17p). Pirtobrutinib was well-tolerated with low-rates of discontinuation due to drug-related toxicity. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

High-Throughput Proteomics Identifies THEMIS2 As Biomarker of Inferior Treatment-Free Survival in Chronic Lymphocytic Leukemia

Background Notwithstanding advances in the prognostication of chronic lymphocytic leukemia (CLL), it remains challenging to distinguish between patients with favorable and unfavorable treatment-free survival (TFS). In addition, the downstream protein correlates of well-known genomic features of CLL are not always clear. To address this, we performed large-scale, unbiased characterization of global intracellular protein expression in a cohort of previously untreated CLL patients. Materials and methods We selected 40 CLL cases (patients in need of treatment within 24 months of sampling) and 40 age- and sex-matched CLL controls (patients without need for treatment for at least 24 months since sampling) from the Dutch natural history CLL cohort. In this cohort, we characterized global intracellular protein expression of magnetically purified B cells using tandem-mass-tagging, followed by high-performance liquid chromatography and triple tandem mass-spectrometry. In addition, recurrent cytogenetic aberrations (del13q, del11q, del17p and trisomy 12), IGHV mutational status and TP53 mutations were characterized using targeted fluorescence in situ hybridization (FISH), Sanger sequencing and next-generation sequencing, respectively. Results Expression of 3268 proteins was quantified in the cohort, allowing for a comprehensive characterization of the CLL proteome. CLL with unmutated IGHV (U-CLL) was associated with significant overexpression of 32 proteins, including ZAP70 and proteins involved in B-cell receptor signaling, such as CD79b and immunoglobulin constant regions mu and delta (adjusted P-value <0.05). CLL with mutated IGHV (M-CLL) was associated with higher intracellular expression of 7 proteins, including both subunits of ferritin (FTH1 and FTL, adjusted P-value <0.05). Trisomy 12 was associated with increased intracellular expression of 32 proteins, 13 (40%) of which are encoded by genes on chromosome 12, and decreased expression of 8 proteins. Many of these hits are concordant with the results of independently performed mass-spectrometry screens. Interestingly, the intracellular concentration of THEMIS2 was significantly higher in cases, compared to controls. THEMIS2 is an protein that is constitutively bound to Grb2, Lyn and PLCγ2 and lowers the threshold for B-cell receptor activation by low-avidity antigens. THEMIS2 protein levels were higher in both U-CLL cases (mean fold change 2, P-value <0.0001) and M-CLL cases (mean fold change 1.7, P-value <0.01), compared to controls. Concordantly, Cox proportional hazards modelling demonstrated that higher concentration of THEMIS2 was significantly associated with shorter TTFT, independent of IGHV mutational status and TP53 aberrations (standardized HR 2.79 [95%CI 1.71-4.54], P<0.0001). ROC analysis indicated a good discriminatory capacity of elevated THEMIS2 concentration, with an AUC of 0.83. THEMIS2 protein quantification by ELISA in a cohort of 40 patients confirmed that higher expression of THEMIS2 was associated with inferior TTFT (median TTFT for patients with THEMIS2 levels above versus below the mean 11 months versus 66 months, P=0.04). Gene expression analysis by qPCR confirmed higher expression of THEMIS2 in cases, compared to controls (mean fold change of 3, P<0.01). Analysis of a publicly available, independently generated mass-spectrometry dataset of 68 CLL patients confirmed the association of elevated intracellular THEMIS2 expression and TFS (median TFS 3 months versus not reached, P<0.0001). Conclusions We present a comprehensive characterization of the proteome of untreated CLL. Of note, we identify elevated gene and protein expression of THEMIS2 as putative biomarker of inferior TTFT, independent of IGHV mutational status and TP53 aberrations. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Fludarabine, Cyclophosphamide and Rituximab (FCR) As First Line Treatment in Patients with Chronic Lymphocytic Leukemia (CLL): A Long-Term Analysis of the German CLL Study Group (GCLLSG) Registry

Introduction: Large randomized trials investigating targeted agents have resulted in a markedly improved progression-free survival (PFS) when compared to standard chemoimmunotherapy. However, for small subgroups with a favorable risk profile, overall survival was not consistently superior for targeted agents. Long-term follow up on FCR suggested that favorable risk patients (pts) benefit significantly from this therapy and can expect an exceptionally long PFS. In addition, targeted first line (1L) therapies for favorable risk pts are reimbursed only in a minority of countries. Here, we report long-term efficacy data of FCR treatment obtained from pts documented within the GCLLSG registry. Methods: Documentation within the GCLLSG registry started in 2013 and included both pts from prospective trials (29.7%), most importantly of the CLL8 trial (22.6%) and CLL10 trial (62.1%) as well as retrospective data. Pts with confirmed diagnosis of CLL who received FCR as 1L treatment were included. Patient characteristics were reported in median, interquartile ranges or frequencies and percentages. Response was reported as response or non-response. Event-free survival (EFS), which was defined as the time from start of (first) FCR treatment to disease progression, initiation of subsequent treatment for CLL or death. EFS was chosen as an endpoint for this report due to concerns that PFS might give unrealistically good results due to lack of documentation. However, PFS and TTNT data will be presented at the meeting. Overall survival was calculated from initiation of 1L treatment for all pts who received 1L treatment after 2013. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated by Cox proportional hazards regression. Variables that were significantly associated with EFS in univariate analyses (significance level was set at 5%) were considered as candidates for the multivariate modelling to identify independent prognostic risk factors. Results: As of September 2021, a total of 5922 pts were enrolled in the registry of which 417 received FCR as 1L treatment between 2003 and 2021. 223 pts (53.5%) received treatment before 2013 and 194 (46.5%) after 2013. Median observation time from 1L treatment was 95.8 (interquartile range 58.7-126.8) months. Patient characteristics showed a median age of 58 (range 24-83) years. Unmutated IGHV (U-CLL) was present in 61.4% of the pts. Regarding genomic aberrations based on the hierarchical model, del(17p) was found in 1.9%, del(11q) in 15.2%, trisomy12 in 15.5%, mono-allelic del(13q) in 34.3% and none of these changes in 33.0% of the pts. 88.8% of the pts responded to first line therapy, 11.2% were documented as non-responder. Median EFS was 71.1 month, for 188 pts no event was documented at the time point of data cut-off. Age group (≤ 65 years, >65 years), del(11q), IGHV mutational status, TP53 status, and serum thymidine kinase (TK) were associated with EFS in univariate analyses. Overall, 116 pts with 67 events were included in the final multivariable model for EFS. U-CLL (HR 1.949 (95%CI: 1.170-3.247; p=0.010) and TK >10 U/l (HR 2.107 (95%CI: 1.153-3.849; p=0.015) were independent adverse prognostic risk factors for EFS. When low TK and M-CLL were combined, the median EFS was not reached, with a 5-year survival rate of 95.8%. In contrast, median EFS was 84.1 months for pts with U-CLL and high TK. In U-CLL pts, median EFS was 87.0 months for pts with TK ≤ 10 U/l, and 58.9 months for pts with TK > 10 U/l. Median overall survival was not reached with a 5-year survival rate of 92.7%. Conclusion: Within this cohort of pts with a long follow up in the GCLLSG registry, FCR treatment was associated with a long EFS especially in pts with a low risk profile exhibiting a mutated IGHV status und low TK. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal