Bruton Tyrosine Kinase Inhibitor Therapy Research Articles

Optimizing BTK Inhibition in Waldenström Macroglobulinemia.

Bruton tyrosine kinase (BTK) inhibitors have become a standard of care in the treatment of patients with Waldenström macroglobulinemia (WM) and are the only medications approved by the FDA to treat these patients. As more patients with WM are treated with BTK inhibitors in the United States and worldwide, it is essential to optimize this therapy by selecting the patients who are more likely to benefit from it, and by managing the unique adverse effects associated with these agents. Herein, we propose a genomic-driven approach to selecting patients with WM who are more likely to experience fast, deep, and durable responses to BTK inhibitors, and provide practical strategies for managing adverse effects, including BTK inhibitor dose reductions, switching to other BTK inhibitors, and abandoning BTK inhibitor therapy. Ongoing clinical trials are evaluating covalent and noncovalent BTK inhibitors alone and in combination, as well as BTK degraders, with exciting results, making the horizon for BTK-targeting therapies in WM bright and hopeful.

A prospective study of zanubrutinib, a Bruton tyrosine kinase inhibitor, in relapsed/refractory idiopathic multicentric Castleman disease.

Relapsed and refractory (R/R) idiopathic multicentric Castleman disease (iMCD) is a clinical challenge with no standard treatment. In this preliminary clinical trial, we investigated the efficacy and safety profiles of a Bruton tyrosine kinase inhibitor (BTKi), zanubrutinib, in patients with R/R iMCD. The primary endpoint was theoverall response rate at Week 12according to theCastleman Disease Collaborative Network (CDCN) response criteria. The trial was terminated early due to a lack of treatment response in the first enrolled 5 patients. Although 3 patients achieved symptomatic response, none of the 5 patients had an overall response by Week 12. One patient had progressive disease and the other 4 had stable disease. The study drug was well tolerated without grade 2 or higher adverse events. Our findings suggest that BTKi therapy is not effective for iMCD, and further attempts at single-agent therapy with zanubrutinib or other BTKis for iMCD should be consideredwith caution and probably avoided. This trial was registered at www.clinialtrials.gov as #NCT04743687.

The Impact of Pausing Bruton Tyrosine Kinase Inhibitor Therapy and Responsiveness of Vaccination in Blood Cancer Patients: Primary Outcome Result for the Randomised Improve Trial

Background: Patients with CLL have profound immunosuppression, higher mortality rates from COVID-19 infection and poorer responses to vaccination. Patients taking continuous Bruton Tyrosine Kinase inhibitor (BTKi) therapy demonstrate the poorest responses to vaccination, despite booster COVID-19 doses. BTKi therapy is taken continuously and is non-selective, inhibiting B cell receptor signalling in healthy B cells, as well as CLL cells. As covalent BTKi therapies have a short half-life and BTK receptor occupancy increases on stopping drug, a temporary pause in BTKi around the time of vaccination may improve immunity. Aim: To assess whether a temporary three-week pause of daily BTKi treatment around COVID-19 vaccination improves the immune response in people with Chronic Lymphocytic Leukaemia (CLL) whilst maintaining disease control. Methods: Patients with CLL in CR/stable PR taking either acalabrutinib or ibrutinib for 1 year or more were recruited to the open-label, prospective, 2-arm, parallel group, multicentre IMPROVE trial (ISRCTN 14197181) at 11 NHS UK hospital sites, prior to their COVID-19 booster vaccination. Participants were randomised (1:1) to either pause BTKi therapy for 3 weeks, starting 6 days before vaccination, or to continue BTKi therapy as usual. Researchers doing the laboratory analyses were blinded to group assignment. The primary outcome was SARS-CoV-2 Spike receptor binding domain (RBD) antibody titres 3 weeks after receiving the COVID-19 booster vaccine dose, assessed in the intention-to treat population. Results: Between Oct 10, 2022 and June 30, 2023, 99 participants with CLL were randomly assigned to continue BTKi (n=49) or pause BTKi (n=50). Mean age of participants was 70.5 years and 71/99 (72%) were male. 63/99 (64%) were on first line CLL therapy, and 51 (52%) were taking Ibrutinib, with the remaining participants taking Acalabrutinib. Participants had a median of 6 previous COVID-19 vaccinations prior to their booster (IQR 4-6). 84 (85%) were given the Bivalent Pfizer booster vaccination, 6 (6%) the Moderna Bivalent, 7 (7%) Sanofi, 1 (1%) unknown and 1 (1%) did not receive a vaccination. The proportion of participants deficient in IgG (<6 g/L); IgA (<0.8g/L) and IgM (<0.6g/L) were similar in both groups at baseline. At baseline, the geometric mean anti-spike RBD antibody titre was 71.6 U/mL (SD 101.3) in the suspend BTKi group and 132.9 U/mL (SD 82.2) in the continue BTKi group. The numbers of participants with no prior response to vaccination (≤ 0.4 U/mL) were 18/50 (36%) in the pause BTKi group and 14/49 (29%) in the continue BTKi group. After 3 weeks, 5/47 (11%) in the pause group and 1/48 (2%) in the continue group, seroconverted. The geometric mean anti-spike RBD antibody titre at 3 weeks was 150.4 U/mL (SD 100.9) in the suspend BTKi group and 151.8 U/mL (SD 109.6) in the continue BTKi group, with a geometric mean ratio (GMR) of 1.830 (95% CI 0.820 - 4.083; p = 0.140; mixed-effects model). There were no intervention-related serious adverse events reported. 4 patients withdrew from study. 2 patients in the pause arm and no patients in the continue arm sought NHS advice during the 3 week vaccination period. 2 patients in the pause arm and 1 patient in the continue arm commenced steroids during the 3 week period. No difference was observed in full blood count parameters between baseline and 3 weeks' in the 2 arms. LDH levels were 191.4 (SD 44.6) and 196.5 (SD 47.4) at baseline and 195.7 (SD 81.8) and 217 (SD 99.7) at 3 weeks' in continue Vs pause arm respectively. Participants self-reported no new or swollen lymph nodes at baseline in either arm, but 4 (8%) reported new or swollen lymph nodes in the pause arm compared with 0 in the continue arm. Compliance was self-reported; 48/49 in the continue group and 47/50 in suspend group confirmed compliance to allocated arm. Interpretation: A 3 week interruption in BTKi around the time of vaccination may improve seroconversion rates in people with CLL but does not boost antibody titre responses overall. Further analysis of secondary endpoints including neutralisation and cellular immunity is ongoing.

Response to Subsequent Novel Therapies and Time to Second Progression-Free Survival Event in the MURANO Trial in Patients with Relapsed/Refractory Chronic Lymphocytic Leukemia Previously Treated with Fixed-Dose Venetoclax Plus Rituximab

Background: The randomized Phase III MURANO trial (NCT02005471) assessed fixed-duration treatment with venetoclax (Ven) plus rituximab (R) in patients (pts) with relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL). Despite improved clinical outcomes (progression-free survival [PFS], overall survival [OS] and time-to-next-treatment [TTNT], as well as minimal residual disease conversion and progressive disease [PD] association [Seymour et al. Blood 2022]) for pts randomized to VenR compared with bendamustine-R (BR), most pts will ultimately require subsequent therapies. However, the efficacy of subsequent treatment after relapse remains largely unexplored. This study was conducted prior to the widespread availability of other targeted therapies, so pts were not previously exposed to targeted therapies prior to MURANO treatment allocation. Here we report response rates to follow-up therapy with Ven-based regimens, or Bruton tyrosine kinase inhibitor (BTKi) therapy, as well as time to the second PFS events from the final analysis of the MURANO trial. Methods: Overall, 389 pts were randomized to VenR (2 years of Ven, with R for the first 6 months) or 6 months of BR. Pts in either arm with PD were followed for disease response to any subsequent anti-CLL therapeutic regimens, PFS and OS. A sub-study, introduced in 2018, allowed pts who developed PD following treatment with VenR or BR to receive the MURANO VenR regimen. Pts who initiated new anti-CLL therapy without a response assessment reported by the investigator, were considered unevaluable. Results : At the final clinical cutoff date of August 3, 2022, all pts had ceased study-specified treatment and the median follow-up of the main study was 85.7 (range: 0-99.2) months. PFS and OS benefits were maintained at the 7-year follow-up (Kater et al. EHA 2023). Overall, 73/194 (37.6%) pts in the VenR arm had not received a next-line therapy at the final cutoff, and 26 pts had died without subsequent therapy. Median TTNT or death with VenR was 63.0 months vs 24.0 months with BR (hazard ratio: 0.30). Following PD, 95/194 (49.0%) pts randomized to VenR and 131/195 (67.2%) pts randomized to BR had received subsequent anti-CLL therapy; the median (range) time off therapy in these pts was 28.3 months (-0.1-68.6) and 17.9 months (0.7-82.4), respectively. Of the 95 VenR pts receiving subsequent anti-CLL therapy, 30 (32.3%) received BTKi therapy (ibrutinib [n=25], acalabrutinib [n=4] and zanubrutinib [n=1]), with 18 ongoing at the time of the final cutoff; 47 (51.6%) received Ven-based therapy, with 12 ongoing at the time of the final cutoff; and 16 (17.2%) received chemoimmunotherapy (CIT). Two pts received a non-CLL therapy for another malignancy so were excluded from the subsequent analysis. Of the 131 BR pts receiving subsequent therapy, 79 (60.3%) received BTKi therapy (ibrutinib [n=69], acalabrutinib [n=6] and zanubrutinib [n=4]), with 20 ongoing at the time of the final cutoff; 17 (13.0%) received Ven-based therapy, with 3 ongoing at the time of the final cutoff; 24 (18.3%) received CIT; and 11 (8.4%) received other novel agents. Median time from randomization to second PFS event was 85.9 months (95% confidence interval [CI]: 81.8-88.2) in pts randomized to VenR and 48.4 months (95% CI: 44.5-56.6) in pts randomized to BR; p<0.0001 ( Figure). Best overall response (BOR; defined as complete remission [CR], CR with incomplete count recovery, partial remission [PR] and nodular PR) rates to first subsequent anti-CLL therapy for pts with evaluable responses were 75/93 (80.6%) for VenR and 85/107 (79.4%) for BR. Among evaluable pts previously treated with VenR and BR, the BOR rate to subsequent BTKi therapy was 19/22 (86.4%) and 51/65 (78.5%), respectively, while BOR rate to subsequent Ven-based therapies was 32/42 (76.2%) and 15/17 (88.2%), respectively. Conclusions: Final data from MURANO demonstrate that, despite the majority of BR pts receiving novel therapies after relapse on MURANO, there was a significantly prolonged time to second PFS event observed in favor of the VenR arm. Pts who had relapsed and received retreatment or crossed over to Ven-based regimens or subsequent BTKi therapy also demonstrated high response rates. These results indicate that early intervention with fixed-duration VenR in R/R CLL is an effective approach and does not compromise subsequent therapy response.

Incidence of Pneumonia Among Bruton Tyrosine Kinase Inhibitors in Chronic Lymphocytic Leukemia: A Systematic Review and Meta-Analysis of Clinical Trials

Introduction: Bruton tyrosine kinase (BTK) signaling is critical for the proliferation and survival of malignant B lymphocytes in chronic lymphocytic leukemia (CLL). BTK inhibitors (BTKi) are used in the front-line setting as well as for relapsed/refractory (R/R) CLL. Three BTKi are currently approved by the United States Food and Drug Administration (US FDA) for CLL - ibrutinib, acalabrutinib, and zanubrutinib. However, there are some uncertainties on the risk of infections, especially pneumonia, from BTKi due to its potential off-target effects and its immunomodulatory effects on innate and adaptive immune response. The newer second-generation BTKi, acalabrutinib and zanubrutinib, have attenuated off-target effects compared to ibrutinib. We hereby evaluate the incidence of pneumonia, including Pneumocystis jirovecii pneumonia (PJP) and other fungal pneumonia, from BTKi monotherapy in patients with treatment naïve as well as relapsed CLL and compare the incidence among different BTKi. Methods: This systematic review identified clinical trials from MEDLINE, Embase, and CENTRAL databases from the inception to 30 June 2023. The number of cases with any grade and at least grade 3 lung infection/pneumonia, PJP and other fungal pneumonia, along with the total number of patients in the arms with BTKi monotherapy were extracted from each trial per the Common Terminology Criteria for Adverse Events (CTCAE) v5.0. The incidence meta-analysis was performed using “meta” package version 6.5-0 of R version 4.2.2, via random-effects model. Pooled incidence and its associated 95% confidence interval (CI) were reported for each outcome .I² statistic was used to determine the heterogeneity of the studies. Subgroup analyses by type of BTKi (ibrutinib, acalabrutinib, and zanubrutinib) and treatment history (treatment-naïve and R/R) were performed. Results: After two rounds of review, eighteen clinical trials containing twenty arms of BTKi monotherapy were eligible for the meta-analysis. Among these, four trials reported the incidences of PJP and three reported on fungal pneumonia. The pooled incidence of any grade pneumonia in patients with CLL on BTKi therapy was 0.13 (95% CI, 0.10-0.16, I2 = 80%) [Figure (Fig) 1a]. The pooled incidence of grade 3 or higher pneumonia was 0.08 (95% CI, 0.06-0.10, I2 = 68%) [Fig 1b]. There were no differences in the incidences of any grade (p = 0.61) or grade 3 and higher pneumonia (p = 0.30) among patients treated with ibrutinib, acalabrutinib, or zanubrutinib in the subgroup analyses [Fig 1c and 1d respectively]. However, the pooled incidences of any grade and grade 3 or higher pneumonia were greater in R/R CLL patients compared to those who were treatment-naïve (0.15 vs 0.07, p<0.01 and 0.10 vs 0.05, p = 0.04, respectively) [Fig 1e and 1f respectively]. The pooled incidences of PJP and other fungal pneumonia were 0.01 (95% CI, 0.00-0.02, I2 = 10%) and 0.01 (95% CI, 0.00-0.02, I2 = 0%), respectively. Conclusion: Our study showed no significant differences in the incidence of pneumonia of any grade or at least grade 3 among patients treated with newer second-generation BTKi vs first-generation BTKi. Risk of pneumonia should not be a factor to choose among BTKi. Of note, the incidence of pneumonia was higher in R/R CLL patients on BTKi therapy when compared to treatment naïve CLL. R/R CLL are likely to have increased infections due to complement dysfunction and progressive immunodeficiency (decreased IgG and IgA levels). Fungal pneumonia, including PJP, are uncommon in CLL, and the subgroup analyses were not able to distinguish any differences among different BTKi. PJP prophylaxis is still considered during BTKi therapy in treatment naïve and R/R CLL, but true risk vs benefit is unknown.

Impact of Real-World Treatment Sequencing Patterns on Time to Next Treatment among Patients with Chronic Lymphocytic Leukemia in the United States

Background: The treatment landscape for chronic lymphocytic leukemia (CLL) is evolving at a rapid pace, with development of several targeted therapies. The real-world applicability of clinical trial effectiveness is markedly influenced by treatment choices, the specific characteristics of patients' diseases, their overall health, and individual preferences. However, there is limited evidence to understand the impact of multiple treatment options on real-world effectiveness in CLL in routine clinical practice. This study aimed to characterize recent real-world treatment sequencing patterns and associated time to next treatment among patients with CLL in the United States. Methods: This retrospective observational study included patients diagnosed with CLL (≥18 years at diagnosis) from January 1, 2018, through January 1, 2023, who received ≥1 treatment after initial diagnosis. Patients were sourced from the ConcertAI RWD360 dataset, a real-world de-identified dataset >6 million patients from across the United States derived from various electronic health record systems and integrated with a large administrative open claims dataset. Patients were followed through the end of the record or death, whichever occurred first. Patients were classified into the following treatment categories: chemotherapy (including bendamustine-based and other chemotherapy), anti-CD20-based, Bruton tyrosine kinase inhibitor (BTKi)-based (ibrutinib, acalabrutinib, or zanubrutinib), and venetoclax-based therapy. Demographic and clinical characteristics, treatment sequencing pattern, and time to next treatment were examined across lines of therapy for each treatment category. Kaplan-Meier analysis was used to estimate median time to next treatment. Results: The study included 3,431 patients with CLL (median age: 69 years; male: 63.8%). There was a significant variation in average age among the 4 treatment groups ( P<0.0001). Compared with the overall population, patients who received anti-CD20-based therapy were slightly older (median age: 71 years), while patients who received venetoclax-based therapy were relatively younger (median age: 67 years). Patients were primarily treated in community rather than academic settings (76.4% vs 21.3%). First-line patients were most commonly treated with BTKi (60.1%), venetoclax (16.0%), and anti-CD20 (15.4%) regimens. Among patients who initiated BTKi therapies, zanubrutinib use (2.6%) was limited; this may be due to the recent approval date (January 2023). Among CLL patients, 35.0% received second-line treatment and BTKi stayed dominant (35.7%), followed by anti-CD20 (29.6%) and venetoclax (25.8%) therapies. From first- to second-line therapy, the prevailing sequencing pattern was from either one BTKi to another BTKi (23.5%), venetoclax to anti-CD20 (13.2%), or BTKi to an anti-CD20 (9.7%). From second- to third-line therapy, patients most frequently switched from anti-CD20 to venetoclax (24.6%), anti-CD20 to BTKi (13.3%), or one BTKi to another BTKi (12.6%). From third- to fourth-line therapy, the predominant sequencing pattern was from venetoclax to anti-CD20 (21.3%), anti-CD20 back to venetoclax (20.6%), or one BTKi to another BTKi (11.6%). Median time to next treatment in first line was significantly longest for patients receiving BTKi (53.9 months) and shortest for patients treated with venetoclax (7.7 months) ( P<0.0001) (Figure 1). Median time to next treatment in second line was not reached among patients using BTKi, while it was significantly shorter for those on venetoclax and anti-CD20 (10.4 months and 1.5 months, respectively; P<0.0001) (Figure 2). Conclusions: This studydemonstrated unique treatment sequencing patterns among patients with CLL in the real-world setting.As the most commonly used regimen, BTKi therapy was shown to have significantly improved time to next treatment compared with other treatment regimens in first and second lines of therapies. Future studies with extended follow-up are needed to allow for assessment of newer treatments and enable evaluation of long-term clinical outcomes.

Real-World Treatment Patterns, Discontinuation and Clinical Outcomes in Patients with B-Cell Lymphoproliferative Diseases Treated with BTK Inhibitors in China

Bruton tyrosine kinase inhibitor (BTKi) has demonstrated substantial efficacy in treating B-cell lymphoproliferative diseases (BLPD). Nonetheless, the significant discontinuation rates due to toxicity or financial reasons cannot be overlooked. In China, empirical evidence on the usage of BTKi remains scarce. To address this, a retrospective cohort study was conducted focused on 673 Chinese patients with BLPD who underwent at least one month of BTKi therapy. Median age at BTKi initiation was 60 years. The median duration on BTKi treatment of the whole cohort was 36.4 months. The median post-BTK survival was not reach. BTKi-based treatment was permanently discontinued in 288 (43.8%) patients during follow-up, mostly attributed to progressive disease. Within the first 6 months of BTKi treatment, 76 patients (26.3%) had early treatment discontinuation. Patients with early discontinuation had extreme worse outcome with a median post-discontinuation survival of only 6.9 months. On multivariate analysis, withdrawal BTKi by toxicity and withdrawal BTKi within 6 months retained to be independent predictors of post-BTK survival, after taking account of the response depth, lines of therapy and baseline cytogenetics including 17p deletion. The decision between BTKi monotherapy and combination therapy, along with the preference for first or second-generation BTKi, exerted no significant impact on survival. These observations contribute valuable real-world insights into the utilization of BTKi in China. We concluded that BTKi is an effective and well-tolerated treatment for long-term use in Chinese patient population. However, it is imperative to stress that a proportion of patients discontinue BTKi early, leading to suboptimal outcomes. This study underscores the importance of adherence to BTKi therapy for improved clinical outcomes in real-world patients.

Fixed Duration Mosunetuzumab Plus Polatuzumab Vedotin Has Promising Efficacy and a Manageable Safety Profile in Patients with BTKi Relapsed/Refractory Mantle Cell Lymphoma: Initial Results from a Phase Ib/II Study

Background: New treatment options are needed for patients (pts) with relapsed/refractory (R/R) mantle cell lymphoma (MCL), especially for pts with progressive disease (PD) after Bruton's tyrosine kinase inhibitor (BTKi) therapy. Outcomes for R/R MCL pts with PD after the BTKi ibrutinib are very poor, demonstrated by a median overall survival of 2.9 months (Martin et al. Blood 2016). While chimeric antigen receptor (CAR) T-cell therapies are approved for pts with R/R MCL; treatment is associated with high toxicity and difficulty with accessibility. Mosunetuzumab (Mosun) is a CD20xCD3 T-cell engaging bispecific antibody that engages and redirects T cells to eliminate malignant B cells. Polatuzumab vedotin (Pola) is a CD79b-targeted antibody-drug conjugate that inhibits cell division and induces apoptosis in B cells. This ongoing Phase Ib/II study (NCT03671018) is investigating Mosun in combination with Pola (M-Pola) in pts with R/R B cell non-Hodgkin lymphoma. Here, we report initial safety and efficacy data from an ongoing Phase II expansion cohort of pts with R/R MCL who had received prior BTKi therapy. Methods: Eligiblepts had histologically confirmed R/R MCL and had received ≥2 prior regimens (including an anti-CD20 agent, BTKi, and anthracycline- or bendamustine-based therapy). Mosun was administered subcutaneously (SC) by step-up dosing on Days (D) 1 (5mg), 8 (45mg), and 15 (45mg) of Cycle (C) 1, then 45mg on D1 of every cycle from C2D1, every 3 weeks for a total of 17 cycles. Pola (1.8mg/kg intravenous [IV] infusion) was administered on D1 of C1-6. All pts received corticosteroid premedication prior to C1 of treatment. From C2, premedication was optional for pts who did not experience cytokine release syndrome (CRS) in the previous cycle. Response was assessed by investigators using Lugano 2014 criteria (Cheson et al. J Clin Oncol 2014). Results: As of October 27, 2022, 20 pts had received M-Pola (n=10 active on treatment, n=1 completed treatment, n=9 discontinued Mosun treatment). Median age of all pts was 68.0 (range: 44-82) years, 75% were male, 95% had Ann Arbor stage III/IV disease, and 40% had a MIPI score ≥6 at study entry. Median number of prior lines of therapy (LOT) was 3 (range: 2-9). All pts had received prior BTKi therapy; 7 pts (35%) had received prior CAR T-cell therapy; and 85% (17/20) of pts were refractory to their last LOT. Median time since last LOT was 1.6 (range: 0-39) months. The proportions of pts with high-risk MCL factors at baseline were: 65% of pts with Ki-67 proliferation index ≥50%; 50% with blastoid/pleomorphic variants; and 20% with TP53 mutation. The overall median time on study was 7.2 (range: 0.4-17.5) months. The most common (≥25%) Mosun and/or Pola-related adverse events (AEs) in all pts (n=20) were CRS (50%), injection site reaction (50%), fatigue (45%), dyspnea (35%), paresthesia (30%), diarrhea (30%), myalgia (30%), infusion-related reaction (25%), and nausea (25%). Two (10%) Grade (Gr) 5 AEs occurred, both of which were due to COVID-19 pneumonia; neither were deemed treatment-related by the investigator. Ten pts (50%) experienced CRS events; 9 pts experienced Gr 1 events, and 1 pt experienced a Gr 2 event, which was managed with tocilizumab and low-flow oxygen. One pt was managed with corticosteroids and no pts required pressors or ICU admission. All CRS events resolved by the data cut-off. Treatment-related neurologic AEs, potentially consistent with ICANs, occurred in 3 pts (15%; Gr 1 confusional state and Gr 2 amnesia, 1 pt; Gr 1 agitation, 1 pt; and Gr 2 memory impairment, 1 pt). Neuropathy occurred in 3 pts (15%); all events were Gr 1. Four pts (20%) had AEs leading to treatment discontinuation: 1 pt with Gr 3 uveitis (related to M-Pola); 1 pt with Gr 3 pneumonitis (related to M-Pola); and 2 pts with Gr 5 COVID-19 pneumonia (both unrelated to M-Pola). Overall response rate (ORR) and complete response (CR) rates were 75% and 70%, respectively (Figure). Best ORR and CR rates were generally consistent in high-risk MCL subgroups (Figure). Median duration of CR was not evaluable (NE; 95% confidence interval: 3.8-NE). Conclusions: Fixed-duration Mosun SC in combination with Pola IV induced high CR rates in pts with R/R MCL who had previously received BTKi therapy, including those in high-risk subgroups and those who had received prior CAR T-cell therapy. CRs were observed early and persisted during the follow up period. M-Pola had a manageable safety profile, and all CRS events were low grade.

Assessing Adoption of Standard of Care and Comparing Clinical and Demographic Differences in First-Line (1L) Treatment (Tx) of Chronic Lymphocytic Leukemia (CLL)

Assessing Adoption of Standard of Care and Comparing Clinical and Demographic Differences in First-Line (1L) Treatment (Tx) of Chronic Lymphocytic Leukemia (CLL)

GLOBRYTE: A Phase III, Open-Label, Multicenter, Randomized Trial Evaluating Glofitamab Monotherapy in Patients with Relapsed or Refractory Mantle Cell Lymphoma

Background and Significance: There is currently no standard of care for patients (pts) with relapsed or refractory (R/R) mantle cell lymphoma (MCL). Although Bruton tyrosine kinase inhibitors (BTKi) have improved clinical outcomes in R/R MCL, there is a high unmet need for new treatment options for pts who do not respond to, or progress through, BTKi therapy. Chimeric antigen receptor (CAR) T-cell therapies, such as brexucabtagene autoleucel, have shown promising outcomes, but alternative systemic therapies are still needed in this pt population. Glofitamab is a CD20xCD3 T-cell-engaging bispecific antibody that redirects T cells to eliminate B cells. A Phase I/II trial of glofitamab monotherapy with step-up dosing (SUD) and obinutuzumab pretreatment (Gpt; 1000 or 2000mg) to mitigate the risk of cytokine release syndrome (CRS) showed high and durable complete response (CR) rates (73.0%) and manageable, mostly low-grade CRS in heavily pretreated pts with R/R MCL (n=37), most of whom had failed prior BTKi therapy (Phillips et al. ASH 2021, Phillips et al. ASH 2022). Study Design and Methods : The GLOBRYTE study (GO43878; EU CT: 2023-503206-37-00) is a Phase III, open-label, multicenter, randomized, controlled trial that will evaluate the efficacy, safety, pharmacokinetics (PK), and pharmacodynamics (biomarkers) of glofitamab monotherapy in pts with R/R MCL, in comparison with an investigator's choice of rituximab + bendamustine (BR) or rituximab + lenalidomide (R-Len). Pts with histologically confirmed R/R MCL who have received ≥1 prior line of systemic therapy (including a BTKi) and have an Eastern Cooperative Oncology Group performance status of 0-2 are eligible for enrollment. Exclusion criteria include leukemic, non-nodal MCL; prior CAR T-cell therapy or CD20xCD3 bispecific antibodies; primary or secondary central nervous system (CNS) lymphoma or history of CNS lymphoma; and current or prior CNS disease (including stroke or transient ischemic attack in the past 2 years and residual neurologic deficits, epilepsy, or CNS vasculitis). Eligible pts will be randomly assigned (1:1) to receive glofitamab or investigator's choice of BR or R-Len stratified by line of therapy (1 vs ≥2) and response to last therapy (relapsed vs refractory). Pts will receive intravenous (IV) Gpt (2000mg) on Day (D) 1 of Cycle (C) 1, 7 days prior to the first glofitamab dose (Gpt may be split over 2 days as 1000mg doses if needed: the second 1000mg dose must be administered ≥1 day before initial glofitamab treatment). Pts will receive glofitamab for a fixed duration of 12 cycles, unless progressive disease (PD) or unacceptable toxicity occurs earlier. Glofitamab IV SUD will be given on C1D8 (2.5mg), C1D15 (10mg), and then the target dose (30mg) on D1 of C2-12 (21-day cycles). Pts randomized to the investigator's choice will receive 375mg/m 2 IV rituximab on D1 in combination with either 90mg/m 2 IV bendamustine on D1-2 of each cycle (BR for six cycles) or 20mg/day oral lenalidomide on D1-21 of each cycle (R-Len until PD); the cycle length for BR or R-Len is 28 days. Crossover to glofitamab from the investigator's choice is permitted in pts with radiologic confirmation of PD ( Figure). The primary endpoint is progression-free survival (PFS) determined by independent review committee (IRC). Treatment comparisons will be made with a 2-sided, level 0.05 stratified log-rank test. Secondary endpoints include overall survival (OS); IRC- and investigator-assessed CR rate, objective response rate, duration of response, and duration of CR; PFS (investigator-assessed); safety; health-related quality of life including time to deterioration in physical functioning or fatigue evaluated by the EORTC QLQ-C30; glofitamab PK; and immune response to glofitamab (including presence of anti-drug antibodies). Response will be determined according to Lugano criteria (Cheson et al. J Clin Oncol 2014). Stratified hazard ratios with 95% confidence intervals (95% CI) will be calculated for PFS and OS, and odds ratios (95% CI) will be calculated for the difference in CR rate and overall response rate between treatment arms. Predictive and prognostic biomarkers (to characterize high-risk subgroups and minimal residual disease kinetics) will also be explored. An estimated 80 sites globally will enroll approximately 182 pts with R/R MCL (glofitamab n=91; BR or R-Len n=91 total) starting in Oct-Nov 2023 (APAC, US, and EU regions).

Comparison of Dietary Intake and Dietary Inflammatory Index in Patients with Chronic Lymphocytic Leukemia By Treatment Status to Cohabitating Controls

Chronic lymphocytic leukemia (CLL) is an incurable disease with a varied presentation ranging from indolent and asymptomatic to morbid and life-limiting. As tumor biology insufficiently explains this variability, we hypothesized that behavioral and environmental factors including diet and the gut microbiome, where diet is a key influence, may influence CLL pathogenesis and response to therapy. We performed a cross-sectional sample and survey collection study of the gut microbiome, blood, and diet in patients with CLL treated at the University of Nebraska Medical Center between 2021-2023. Eligible subjects included 1) untreated CLL with Rai stage 2-4 disease (untreated CLL), 2) CLL treated with a Bruton's tyrosine kinase inhibitor (BTKi), and 3) individuals without cancer cohabitating with enrolled CLL subjects (control). All subjects provided stool samples for microbial analysis, and subjects with CLL provided blood for serum cytokine analysis. All subjects completed the Diet History Questionnaire version 3.0 (DHQ-3). The DHQ-3 is a self-administered food frequency questionnaire, where participants complete 135 questions on food/beverages and 26 on dietary supplements consumed in the past month. A total and component healthy eating index (HEI) score was derived from the DHQ-3 and represents how well diet intake corresponds to the dietary guidelines recommended by the United States Department of Agriculture and Health and Human Services. The HEI is based on 13 individual components (Figure 1) and scored from 0-100, where higher scores indicate healthier diets. Inflammatory capacity of the diet was assessed by the Dietary Inflammatory Index (DII) (Shivappa et al, Public Health Nutrition, 2013), a measure of dietary components associated with serum markers of inflammation. The DII has a range of scores up to 7.98 suggestive of greater systemic inflammation (median DII score 0.23), and a minimum of -8.87, suggestive of consumption of anti-inflammatory foods. The DII was calculated and compared between each cohort. Statistical analysis was performed using ANOVA. A total of 58 subjects enrolled on the study, 42 with CLL and 16 cohabitating controls. A total of 27 subjects were included in the analysis after data cleaning. Fifteen subjects (56%) were treated with a BTKi, 5 (19%) had untreated Rai stage 2 disease, and 7 (26%) were cohabitating controls. Median ages (72 vs 67 vs 71 for BTKi, untreated, control, respectively) were similar. Median absolute lymphocyte count was 3.2 cells x10^3/µL (1.3 - 131 range) in the BTKi and 55 cells x10^3/µL (13-134 range) in the untreated cohort. There were 5/15 (33%) with 17p deletion and/or p53 mutation in the BTKi cohort and 2/5 (40%) in the untreated cohort. Median time from diagnosis to study entry was 30 months (range 3-151 months) in the untreated cohort, and median time on BTKi therapy was 30 months (range 2-92 months). Within the BTKi cohort, 33% received ibrutinib, 20% received zanubrutinib, and 47% received acalabrutinib. Overall dietary habits were largely similar between the 3 cohorts (Table 1). The mean total HEI score was higher in the untreated (66) and control (66) populations compared to the BTKi cohort (59) ( p = 0.23), although not significantly different. These scores are similar to the 2020 median score of 61 for Americans 60 years and above. Added sugar intake was highest in the untreated cohort (HEI component score of 9.6, 6.3, 8.6 untreated, BTKi, control p = 0.005, respectively) (Figure 1). After calculating the DII for each cohort, no statistically significant differences were observed (Table 1). The range of DII scores across subjects was -5.2 - 4.0, within the expected range for DII calculations. DII scores were 0.44, 0.2, 0.82 p = 0.89 for BTKI, untreated CLL, and control cohorts respectively. To our knowledge, this study is the first to analyze dietary patterns in well-defined homogenous CLL populations (BTKi vs Rai stage 2+ CLL cohort) and compare them to cohabitating individuals. Although overall dietary patterns and DII were similar across cohorts, slight differences in added sugar intake was observed between the cohorts, suggestive that subtle yet important dietary differences may be observed. These data provide a baseline to study personalize dietary approaches to patients with CLL, who increasingly ask clinicians for nutritional interventions as part of their comprehensive cancer care.

Pre-Existing Cardiovascular Disease Increases the Risk of Cardiovascular Adverse Events during Bruton Tyrosine Kinase Inhibitor Therapy

Background Bruton tyrosine kinase inhibitors (BTKis) have revolutionized the treatment of B-cell neoplasms. BTKi treatment has been associated with a higher incidence of cardiovascular adverse events (CVAE), which contribute significantly to morbidity and mortality in this population. Ibrutinib has been more strongly associated with CVAE compared to more selective 2 nd-generation BTKis. Although predisposing factors are not clear, pre-existing cardiovascular disease (CVD) appears to increase the risk of atrial arrhythmias and mortality during BTKi treatment. Our primary objective was to evaluate and compare the rate of CVAE during BTKi therapy, in individuals with and without pre-existing CVD. In addition, we aimed to compare the outcomes of patients treated with 1 st vs. 2 nd generation BTKis and characterize management decisions. Methods A retrospective review was conducted on patients treated with BTKis for hematologic malignancies from 2013 to 2022 at Beth Israel Deaconess Medical Center. Exclusion criteria included prior treatment with anthracyclines and BTKis, prescription of BTKi therapy without administration, prior BTKi treatment for graft-vs-host disease, and loss to follow-up. CVAE were defined as new-onset or worsening atrial fibrillation (AF), new-onset or worsening hypertension (HTN), supraventricular or ventricular arrhythmias, and sudden cardiac death. Pre-existing CVD included coronary artery disease, congestive heart failure, cerebrovascular disease, and pulmonary HTN. Student's t-test and Fisher's exact test were performed to compare the differences in continuous and categorical variables between patients with and without pre-existing CVD, respectively. Logistic regression analyses were performed to evaluate the association between pre-existing CVD and CVAE. All statistics were performed using R version 4.3. Results We identified 274 patients and 180 met inclusion criteria. Primary indications were Chronic Lymphocytic Leukemia (CLL) in 106 patients (60%), Mantle Cell Lymphoma (MCL) in 31 (17.2%), Diffuse Large B-Cell Lymphoma (DLBCL) in 17 (9.4%), and Waldenström Macroglobulinemia (WM) in 16 (8.9%). In terms of BTKi selection, 141 patients (78.3%) received ibrutinib, 35 (19.4%) acalabrutinib, and 4 (2.2%) zanubrutinib. Prevalent comorbidities were HTN in 103 patients (57%), dyslipidemia in 80 (44%), and diabetes in 26 (14%). Overall, 49 patients (27.2%) had preexisting CVD, and 21 (11.6%) experienced CVAE during BTKi therapy. In our cohort, (11/49) patients with pre-existing CVD developed CVAE, compared to (10/131) patients without pre-existing CVD, (22% vs 8% respectively), OR 3.38 (95%CI = [1.3, 8.5], p-value= 0.01). The OR remained robust ranging from 3.4 to 4.1 (p < 0.05) in multiple adjusted logistic regression models, accounting for imbalances in gender, comorbidities, type of BTKi, and baseline medications. Patients with pre-existing CVD had significantly higher odds of developing new or worsening AF, (16% vs. 5% respectively), OR = 3.94, (95%CI = [1.3, 12.0], p-value= 0.02) (Table 1). In subgroup analysis, patients treated with 1 st generation BTKis had a numerically higher rate of CVAE than those treated with 2 nd generation BTKis, OR = 6.28 (95%CI = [0.8, 48.3], p-value= 0.08) (Table 2). Regarding management, BTKi treatment was discontinued in 13 patients (62%) and continued in 8 (38%). Medical interventions were required in 17 patients (80%). In contrast, the event resolved in 4 patients (19%) with only BTKi discontinuation. Following CVAE, 3 patients (14%) were transitioned to a 2 nd generation BTKi with complete resolution. Conclusions CVAE remain significant contributors to treatment discontinuation. Patients treated with 1st-generation BTKis and pre-existing CVD had significantly higher odds of developing CVAE. Our study is the first to evaluate the impact of pre-existing CVD on CVAE during treatment with 2nd-generation BTKis. Patients on Ibrutinib developed more CVAE compared to patients on 2nd-generation BTKis, though differences were not statistically significant. This study was limited due to its retrospective and single-centered nature. Results highlight the need for structured approaches to prevent and promptly detect CVAE, particularly in patients with pre-existing CVD.

Treatment Effectiveness with Venetoclax-Based Therapy after Bruton Tyrosine Kinase Inhibitors in Chronic Lymphocytic Leukemia: An International Real-World Study

Introduction: Venetoclax has demonstrated consistent efficacy and manageable toxicity in patients with previously untreated or relapsed/refractory (R/R) chronic lymphocytic leukemia/small lymphocytic leukemia (CLL/SLL). However, evidence on venetoclax use in patients previously treated with Bruton tyrosine kinase inhibitors (BTKi) is limited. This real-world evidence (RWE) study assessed clinical outcomes of patients who received venetoclax after covalent BTKi (cBTKi) therapy, i.e., response rates, time to next treatment or death (TTNT-D), and progression-free survival (PFS), overall and stratified by line of therapy. Methods: The CLL Collaborative Study of Real-World Evidence (CORE), a retrospective, international, observational study (23 centers) provided data for this analysis. Adult patients diagnosed with CLL/SLL were included if they received a venetoclax-based regimen after discontinuation of a cBTKi-based regimen. Baseline characteristics at venetoclax initiation were summarized using descriptive statistics. Overall response rate (ORR) was calculated as the proportion of patients with complete response (CR) or partial response (PR) among patients with documented responses as recorded in the patients' medical charts based on physician assessment. TTNT-D was measured from date of venetoclax initiation to change of treatment/death (event) or end of follow-up, while PFS was measured from date of venetoclax initiation to disease progression/death (event) or end of follow-up. Outcomes were reported for the overall population and stratified by line of therapy (1L→2L and 2L→3L) and also by with and without CT/CIT exposure prior to cBTKi for 2L→3L. Results: Of the 2,020 patients included in CORE, 1,287 (63.7%) received a cBTKi-based regimen in ≥1 line of therapy; 184 patients (14.3%) discontinued cBTKi (intolerance: 83 [45.1%], progression: 78 [42.4%]) and initiated venetoclax-based therapy (115 venetoclax monotherapy; 69 venetoclax combined with rituximab or obinutuzumab). Mean age at venetoclax initiation was 68.6 (median: 68.2) years old, 69.0% were male, and 31.0% had Medicare. Among tested patients, 41/61 (67.2%) had unmutated IGHV, and 28/109 (25.7%) had 17p deletion or TP53 mutation at venetoclax initiation. Average follow-up time from initiation of venetoclax therapy was 19.6 months (median: 16.6). Of the 127 patients (69.0%) with a documented response, the ORR was 78.0% (CR: 43.3%, PR: 34.6%). The median TTNT-D for these patients was 39.5 months (95% CI: 30.4, not reached [NR]) with 12- and 18-month rates of 82.3% and 72.4%, respectively. The median PFS was 43.2 months (95% CI: 31.9, NR), with 12- and 18- month PFS rates of 82.8% and 75.1%, respectively. Among patients who started venetoclax-based therapy post-cBTKi as 1L→2L (n=65), the ORR was 84.1% (CR: 54.5%, PR: 29.5%, out of 44 documented). The median TTNT-D for these patients was NR (95% CI: 31.9, NR) but the 12- and 18-month rates were 85.0% and 73.9%, respectively. The median PFS was 43.2 months (95% CI: 39.5, NR) with 12- and 18- month rates of 86.4% and 81.8%, respectively. Among patients who started venetoclax-based therapy post-cBTKi as 2L→3L (n=67), the ORR was 78.3% (CR: 41.3%, PR: 37.0%, out of 46 documented). The median TTNT-D for these patients was 44.2 months (95% CI: 37.0, NR) with 12- and 18-month rates were 83.1% and 76.5%, respectively. The median PFS for these patients was 44.1 months (95% CI: 31.8, NR) with 12- and 18- months rates were 85.2% and 80.4%, respectively. The results for ORR, TTNT-D, and PFS were also similar for those with and without CT/CIT exposure prior to cBTKi. Conclusions: In this multicenter real-world study, results demonstrate that venetoclax is effective overall and also when used either in 2L or 3L following cBTKi therapy. Additionally, even with prior CT/CIT exposure, results support that venetoclax-based therapy remains effective as a therapeutic option. Thus, this study demonstrates that venetoclax-based therapy post-cBTKi is associated with durable remission. These results are especially timely as the CLL treatment paradigm continues to evolve with multiple treatment options available, providing clinicians with valuable evidence to inform modern clinical practice. Further analysis of this study with larger cohorts and longer follow-up time will be undertaken as part of future work to grow this body of evidence.

Multicenter Study to Assess the Outcomes and Prognosis of Richter's Transformation in the Era of Novel Agents and Cell Therapy

INTRODUCTION: Richter's transformation (RT) is the transformation of chronic lymphocytic leukemia or small lymphocytic lymphoma (CLL/SLL) into an aggressive lymphoma, most commonly diffuse large B-cell lymphoma (DLBCL). RT occurs in 2-10% of CLL patients, usually between 2-5 years after CLL diagnosis. The prognosis of RT is poor and the historical median overall survival (OS) after diagnosis is about 8-14 months. However, with the development of novel therapeutic agents including Bruton tyrosine kinase inhibitors (BTKi) and anti-CD19 CAR T-cell therapy, the natural history and prognosis of RT have evolved. To date there is limited data on the prognosis and management of RT in the era of novel therapies. To better understand the prognosis, impact of new therapeutics, and survival for RT in the modern era we performed a multicenter retrospective study to assess the outcomes of RT. METHODS: We performed a multicenter retrospective study including 4 US centers evaluating patients who were diagnosed with RT between 2012-2022 with the current analysis limited to those patients with large B-cell lymphoma transformation. Statistical analyses include descriptive statistics, t-tests for normally distributed continuous variables, non-parametric tests for skewed variables, and chi-square for categorical variables. Overall survival (OS) was calculated using Kaplan-Meier estimates. RESULTS: We analyzed 78 patients with DLBCL transformation from underlying CLL. The median age at RT diagnosis was 66 years (43-84 years). Most patients had advanced stage III-IV disease 92% (n=72). Extranodal disease was present in 68% (n=53). Among 31 patients with 17p deletion or p53 mutational data available at the time of CLL diagnosis, one of these findings was present in 18 patients. Patients had 2 median lines (range 0-7) of treatment for CLL prior to RT diagnosis. 49% (n=38) had BTKi exposure and 28% (n=22) had Venetoclax exposure before RT diagnosis. 24% (n=19) had no prior treatment for CLL before RT. The median time from CLL to RT diagnosis was 42.5 (0-332) months. Median lines of therapy for RT were 2 (range 1-8). The most common frontline regimens for RT included R-CHOP/ R-CHOP-like backbone in 58% (n=45) or high intensity chemoimmunotherapy regimens (R-EPOCH/CVAD) in 14% (n=11). Overall response rate (ORR) to frontline treatment was 56% (complete response (CR)=32/partial response (PR)=12). Of the patients who received 1 st line treatment and achieved a CR/PR (n=44), the 1-year duration of response (DOR) was 50% and the median DOR was 14 months. Fifty-one patients either relapsed or had refractory/progressive disease after frontline treatment and 48 patients received further treatment. Among these 48 patients, 29% (n=14) received a covalent or a non-covalent BTKi in the 2 nd or higher line setting, with an ORR of 43% (CR=4, PR=2). 23% (n=11) received venetoclax with/without other agents in the 2 nd or higher line setting, with an ORR of 36% (CR=3, PR=1). In total, 17 patients received CD19 based CAR T-cell therapy as part of treatment for RT, all in a second or later line of treatment. The ORR and CR rate to this therapy was 82% (n=14). Of these 14 responding patients, the 1-year DOR was 57% and the median DOR was not reached. 12 patients underwent allogeneic transplant (alloHCT), 11/12 as a consolidative treatment option. At first disease assessment after allo-HCT, the ORR was 92% (CR=11). Of the 11 responders, the 1-year DOR was 73% and the median DOR was 42 months. For the entire cohort (n=78), the 1-year OS was 62% and the median OS was 31 months (95% CI 22-NR), which suggest improvement compared to historical reports. CONCLUSION Although RT has a poor prognosis, with the use of novel therapies such as BTKi and CAR T-cell therapy, the overall survival of these patients has improved in the current era. The overall response to chemoimmunotherapy in the first line setting remains poor. Despite this, advances in the management of RT with incorporation of targeted and cellular therapies has improved clinical outcomes of RT. Incorporating these agents either alone or in combination with chemoimmunotherapy in the earlier setting may further improve outcomes in patients with this aggressive disease.

Real-World Switching Pattern, Persistence, and Associated Healthcare Resource Utilization of Bruton Tyrosine Kinase Inhibitors for the Treatment of Mantle Cell Lymphoma in the United States

Introduction: Mantle cell lymphoma (MCL) is an aggressive form of B-cell non-Hodgkin's lymphoma. While incurable, MCL can be controlled for a prolonged period of time, but typically becomes refractory or relapsed and requires additional treatment. Bruton tyrosine kinase inhibitors (BTKi) are approved for relapse/refractory MCL and recommended by the National Comprehensive Cancer Network (NCCN ®); However, it is unclear how BTKi are being utilized and switched in the real-world patient populations. This study aimed to examine treatment patterns, persistence, and associated healthcare resource utilization of BTKi use in patients with MCL in the US. Methods: A retrospective observational study was conducted using Symphony Integrated Dataverse (IDV ®), a comprehensive, longitudinal, open-claims database and integrated Electronic Medical Record (EMR) data. Patients aged ≥18 years with ≥1 diagnosis for MCL and initiated a BTKi between 1/1/20 and 12/31/22 were included in the study. Patients were required to be continuously enrolled for 365 days leading up to the index date and ≥90 days following the index date (date of BTKi initiation). The full patient history in the database was used to identify previous BTKi use and analyze switching patterns for each patient. Three mutually exclusive cohorts (ibrutinib, acalabrutinib, zanubrutinib) were developed based on first-initiated BTKi. Patients were followed until the end of the study period (3/31/23) or lost to follow-up. Treatment switching pattern, duration, persistence, time to discontinuation (TTD), and healthcare resource utilization (HCRU) were examined by each BTKi cohort. Treatment duration was defined as time from BTKi initiation to the end date of last BTKi prescription. TTD was defined as time from BTKi initiation to the end date of the BTKi prescription that had a gap of >60 days with a subsequent BTKi prescription. Treatment persistence was evaluated as the proportion of patients that were continually prescribed BTKi (≥80% proportion of days covered) across 30-day intervals. HCRU was measured by number of outpatient visits and inpatient services, per patient per month (PPPM), during the treatment regimen. Results: BTKi switching patterns were analyzed for the 1,674 patients that initiated any BTKi therapy during study period (acalabrutinib [n= 697]; ibrutinib [n=693]; zanubrutinib [n=284]). Switching rates were 23.8% for ibrutinib, 5.6% for acalabrutinib, and 2.8% for the zanubrutinib cohort. In the ibrutinib cohort, the majority of patients switched to acalabrutinib (72.7%). Of those who switched from acalabrutinib, more than half (59.9%) switched to zanubrutinib. Of those who switched in zanubrutinib cohort, they were equally switched to ibrutinib and acalabrutinib (Table 1). Mean outpatient visits PPPM were 1.39 for patients who initiated with ibrutinib then switched to zanubrutinib, and 1.49 for those who switched to acalabrutinib. Mean inpatient services PPPM were 0.39 for patients who switched from ibrutinib to zanubrutinib, and 0.59 for those who switched to acalabrutinib. The 3 BTKi cohorts were similar across sociodemographic characteristics. The zanubrutinib cohort had higher median TTD (days) (188.5) compared to ibrutinib (161.5) and acalabrutinib (179), as well as higher median treatment duration (200) compared to ibrutinib (171) and acalabrutinib (194). Among MCL patients continuously enrolled for ≥ 360 days, zanubrutinib patients consistently had higher persistence rates (p=0.0079. Figure 1). Persistence at 90-days was 66.9% for zanubrutinib compared to 56.3% for ibrutinib and 62.7% for acalabrutinib. After 360 days, zanubrutinib continued to have the highest persistence (16.9%) compared to ibrutinib (10.8%) or acalabrutinib (13.2%). Zanubrutinib had the least number of mean inpatient services PPPM (0.56) compared to ibrutinib (0.83) and acalabrutinib (0.71) and mean outpatient visits-zanubrutinib (1.53), ibrutinib (1.81), acalabrutinib (1.59). Conclusions: This real-world study suggested that US patients with MCL receiving zanubrutinib showed longer treatment persistence, treatment duration and TTD, as well as lower switching rates and HCRU compared to those receiving acalabrutinib and ibrutinib.

Molecular Analysis at Relapse of Patients Treated on the Ibrutinib and Rituximab Arm of the National Multi-Centre Phase III FLAIR Study in Previously Untreated CLL Patients

Background The NCRI FLAIR trial confirmed ibrutinib + rituximab (IR) improved progression free survival (PFS) over FCR in untreated CLL. Durable responses are achieved on continuous Bruton's tyrosine kinase inhibitor (BTKi) therapy, but acquired resistance mutations in BTK, and PLCG2 are reported in up to 80% of relapsed/refractory patients (pts) failing BTKi often detected at low variant allele frequencies (VAF) several months before relapse. Their frequency, evolutionary dynamics, and relevance to progression in the upfront-treatment setting are poorly characterised. We present the observed clonal evolution in standard risk pts with disease progression (DP) on IR, integrating next generation sequencing (NGS) with serial measurable disease monitoring by flow cytometry, and tracking individual BTK mutations ( BTKmt) by digital droplet PCR (ddPCR) from initial detection to DP. Methods 771 randomised pts to FCR (n=385) or IR (n=386). Pts treated with IR received rituximab at 375 mg/m 2 on D1/C1 and 500 mg/m 2 on D1/C 2-6 of every 28-days. I was given orally at 420 mg/day for up to 72 mo. All 61 DP pts on IR were included in the analysis. DNA from baseline and progression peripheral blood (PB) samples were processed for sequencing of 33 genes recurrently mutated in lymphoid malignancies including BTK (exon 15) and PLCG2 (exons 19-20) with an Illumina MiSeq. Variants were reported down to minimum VAF of 3-5% and coverage of 100X. Low VAF (3-6%) BTKmt were validated by ddPCR using the QX200 ddPCR protocol (sensitivity 1-0.1%). ddPCR was used for the individual serial analysis at baseline and 6 monthly in pts with confirmed BTKhot spot mutations (p.C481S (c.1441T>A, c.1442G>C)), p.C481R (c.1441T>C), p.T474I (c.1421C>T) and presented with concurrent PB MRD monitoring using highly sensitive flow cytometry with a detection limit of one CLL cell in 100,000leukocytes (0·001%). Results 61/386 pts progressed after a median follow up of 44 mo. on I with 50/61 pts progressing after >24 mo. No deaths were recorded before DP. 47/61 IR DP samples were sequenced by MiSeq, 10 further samples with low disease burden were only analysed by ddPCR for hotspot BTKmt. 7/47 sequenced at baseline and DP, developed new isolated mutations in ATM, SF3B1, NOTCH1, BIRC3, BRAF, KLF2, CDKNB1 or TRAF2. The most frequently mutated gene at DP was BTK. From 57/61 sequenced samples at DP, 7 were found to have hotspot BTKmt most with multiple mutations (Fig/Table). No BTKmt detected at DP were detected at baseline by NGS or ddPCR. One pt had a PLCG2 mutation at DP (VAF 33.3%). The 8 BTKmt/ PLCG2 mt IR progressions were mostly in late DP pts (median 60.3 mo.) compared to a median time to DP of 54.3 mo in BTKwt/ PLCG2wt pts. The majority of BTKmt IR DP (5/7) were reported after stopping therapy at 72 mo. 6 monthly samples during I were studied for BTKmt. Evolution of BTKmt in the context of increasing disease burden on I, shows a steady rise in the VAF preceding frank DP (Fig). 148/386 (38.3%) IR pts were 100% homologous to germline IGHV unmutated and 31/148 (20.9%) progressed. 12/15 pts, who acquired additional mutations at DP were IGHV unmutated and 9/12 were 100% homologous to germline including 6/8 with acquired BTK/PLCG2 mutations. Conclusion In upfront IR treated standard risk CLL pts 15.8% progressed (61/386), the majority late. Only 13% of the IR DP cohort (8/61) had a BTK/PLCG2 mutation, suggesting other non- BTK/PLCG2 mutations or disease related factors as contributors to DP after initial response in the upfront setting. Interestingly, the background mutation profile did not change from baseline in those who acquired BTK/PLCG2 mutations at DP, but 7/15 acquired non- BTK/ PLCG2mutations at DP. The majority of IR DP with BTK/PLCG2 mutations (6/8), were 100% homologous to germline IGHV unmutated, suggesting an inherent higher risk disease profile as a risk factor for acquiring BTKmt with prolonged BTKi therapy. BTK/PLCG2 mutations were enriched amongst very late progressors with 6/8 pts progressing shortly after stopping therapy at 72 mo., which is later than previously reported for relapsed/refractory CLL pts.

Narazaciclib, a Differentiated CDK4/6 Antagonist, Prolongs Cell Cycle Arrest and Metabolomic Reprogramming, Enabling Restoration of Ibrutinib Sensitivity in Btki-Resistant Mantle Cell Lymphoma

Bruton tyrosine kinase inhibitors (BTKi) have transformed the therapeutic landscape of mantle cell lymphoma (MCL); however, primary and acquired resistance to these agents remains a challenge. Previous studies have suggested that narazaciclib (ON123300), a second-generation, orally bioavailable and clinical-stage CDK4/6 inhibitor (CDKi), may trigger cell cycle arrest and significant tumor growth inhibition (TGI) in BTKi-resistant MCL. We compared the efficacy and safety profiles of narazaciclib with three health authority-approved CDKi (palbociclib, abemaciclib or ribociclib) in association with covalent (ibrutinib, acalabrutinib) and non-covalent (pirtobrutinib, ARQ-531) BTKi, across a panel of 10 MCL cell lines with distinct sensitivity to the first-in-class BTKi, ibrutinib. We integrated RNA sequencing and gene set enrichment analysis (GSEA) coupled to phospho-proteomics and kinase-substrate enrichment analysis (KSEA) to unravel the molecular bases of BTKi-CDKi drug interaction in MCL. CellTiter-Glo proliferation assay, FACS-mediated quantification of cell cycle and apoptosis, RT-PCR and western blot approaches followed by Seahorse-mediated metabolic assays were carried out for validation purposes. Finally, we evaluated the safety and efficacy of narazaciclib/ibrutinib combo in vivo in three immune-competent chicken embryo chorioallantoic membrane (CAM) MCL xenograft models. We found that narazaciclib exhibited the highest antitumor activity among MCL cell lines (mean IC 50: 3.61 ± 2.1 µM), regardless of the sensitivity of these to ibrutinib. Although there was no correlation between CDKi sensitivity and direct repression of the CDK4/CDK6-pRb pathway in MCL, transcriptomic and phenotypic analyses revealed a predominant downregulation of E2F target genes and G2/M checkpoint response upon narazaciclib treatment. This feature was linked to intracellular accumulation of p21, p16, and phospho-p27, decreased mitotic index, G1 cell cycle blockade, and apoptosis onset. When combined with ibrutinib, but not with the second-generation acalabrutinib, narazaciclib achieved significant synergistic antitumor activity in both BTKi-sensitive and BTKi-resistant cells. The combination was not associated with improved apoptosis, but rather with a slight but constant augmentation in G1 phase blockade and the down-modulation of cell cycle-associated transcriptome, although similar features were found when substituting narazaciclib with abemaciclib. The integration of transcriptomic and phospho-proteomic synergistic signatures further revealed that narazaciclib-ibrutinib combo modulated signatures related to DNA repair, P53 signaling, and glycolytic activity. Accordingly, in this model, narazaciclib/ibrutinib-exposed cells underwent a metabolic switch from glycolytic to oxidative phosphorylation (OxPhos) phenotype accompanied by intracellular accumulation of mitochondria and increased mtDNA copy number. This switch appeared to be specific to MCL cells rendered refractory to ibrutinib upon activation of alternative NFkB signaling, as it was not found in MCL-BTKmut cells. In vivo, while narazaciclib single agent achieved a moderate TGI in the CAM model, the narazaciclib/ibrutinib combo reduced tumor spreading by 65% and allowed a 50% reduction in malignant B cell infiltration into host bone marrow, with no detectable toxicity. In conclusion, our findings demonstrate that narazaciclib is safe and effective as a single agent in preclinical models of MCL, including BTKi-resistant cases. Its combination with ibrutinib achieved a synergistic tumoricidal effect in vitro and in vivo, accelerating cell cycle blockade and reverting the metabolic reprogramming characterizing MCL refractoriness to BTKi therapy.

Real-World Effectiveness and Safety Outcomes of Acalabrutinib Treatment By Line of Therapy in Patients with Chronic Lymphocytic Leukemia and/or Small Lymphocytic Lymphoma

Background: Acalabrutinib is a second-generation Bruton tyrosine kinase inhibitor (BTKi) approved by the Food and Drug Administration for the treatment of chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL). Data from phase 3, randomized, controlled trials of acalabrutinib, as monotherapy or in combination with obinutuzumab, in patients with treatment-naive (TN) and relapsed/refractory (R/R) CLL with long-term follow-up, including ELEVATE-TN, ELEVATE-RR, and ASCEND, have demonstrated sustained improvement vs comparators in progression-free survival and overall survival (OS) with cardiovascular (CV) and bleeding events consistent with previous reports (Sharman et al. J Clin Oncol. 2021; Byrd et al. J Clin Oncol. 2021; Ghia et al. Blood. 2022). As real-world evidence of the acalabrutinib effectiveness and safety profile is limited in CLL/SLL patients, this study aimed to describe time to next treatment (TTNT), OS, and CV and bleeding events in patients receiving first-line (1L) and later-line (2L+) acalabrutinib for the treatment of CLL/SLL in the real-world setting. Methods: A retrospective, observational analysis was conducted utilizing the Optum Clinformatics © Data Mart claims and electronic medical record database to identify patients aged ≥18 years with TN or R/R CLL/SLL who initiated acalabrutinib in any line of therapy (LoT) on or after November 21, 2019 (FDA approval date for acalabrutinib). Patients with CLL/SLL were required to have ≥6 months of continuous enrollment in the Optum database system prior to acalabrutinib treatment initiation. Patients were followed until the earliest of last day of data availability, death, or end of study period (September 30, 2022). Treatment effectiveness was described as TTNT (time from acalabrutinib initiation to next LoT or death of any cause) and OS (time from acalabrutinib initiation to date of death from any cause or end of study period). The Kaplan-Meier (KM) method was used to estimate TTNT and OS. Patients who continued treatment at the last follow-up were censored. CV and bleeding events were assessed in all patients who initiated acalabrutinib. All outcomes were evaluated in patients who received 1L or 2L+ acalabrutinib therapy. Results: A total of 530 patients were identified and included in the analysis. Of these patients, 63% (n=334) received 1L acalabrutinib and 37% (n=196) received 2L+ acalabrutinib. At acalabrutinib initiation, the mean age was 72.8 years in the 1L cohort and 74.2 years in the 2L+ cohort; 61.7% (121/196) of patients treated with 2L+ acalabrutinib had prior BTKi therapy prior to acalabrutinib initiation (ibrutinib, n=120; zanubrutinib, n=1). Distributions of gender and race were similar between the cohorts. At baseline, 18.1%, 75.3%, and 16.0% of patients had atrial fibrillation/flutter, hypertension, and bleeding episodes, respectively. With a median follow-up of 8.9 months in the 1L cohort and 12.4 months in the 2L+ cohort, the median TTNT and OS were not reached in either cohort. At 18 months, the proportion of patients remaining on treatment was 82% in the 1L cohort and 78% in the 2L+ cohort ( Figure 1). Of the patients that progressed, the median TTNT was 4.0 months in the 1L cohort (n=33) and 4.2 months in the 2L cohort (n=31). The 18-month OS rate was 90% and 85% for the 1L and 2L+ cohorts, respectively ( Figure 2). After initiation of acalabrutinib treatment, the incidence rates of atrial fibrillation/flutter, hypertension, and bleeding events were 2.7%, 8.9%, and 2.7% of patients in the 1L cohort and 7.4%, 2.4%, and 3.3% of patients in the 2L+ cohort, respectively, who had no history of these events prior to treatment with acalabrutinib. Conclusions: This is the first study demonstrating real-world effectiveness (OS and TTNT) and safety data of acalabrutinib treatment in first-line and later-line therapy. While clinical trial and clinical practice settings may differ, overall, the survival findings in this study were similar to those of acalabrutinib trials. The observed incidence rates of CV and bleeding events were not inconsistent with those observed in published acalabrutinib trials.

A CD5 Gene Signature Identifies Diffuse Large B-Cell Lymphomas Sensitive to Brutonʼs Tyrosine Kinase Inhibition

Introduction: Diffuse large B-cell lymphomas (DLBCLs) with a non-germinal center B cell-like (non-GCB) cell-of-origin are frequently driven by genetic alterations that culminate in constitutive B-cell receptor (BCR) signaling, which has inspired the exploration of Bruton's tyrosine kinase inhibitors (BTKi) in these lymphomas. However, the phase III PHOENIX study that randomized untreated, non-GCB DLBCL patients to R-CHOP plus placebo or ibrutinib failed to meet its primary endpoint of event-free survival (Younes et al. 2019), which suggests that cell-of-origin alone is an insufficient biomarker to predict BTKi sensitivity in DLBCL. More recently, a DLBCL genetic classifier termed LymphGen has identified distinct subtypes (MCD and N1) of non-GCB DLBCL that benefit from the addition of BTKi to R-CHOP (Wilson et al. 2021). However, genetic classifiers are complex and difficult to implement in routine clinical settings and may fail to capture all DLBCLs that benefit from BTKi. Therefore, we sought to identify a straightforward biomarker of BTKi responsiveness in DLBCL with greater precision than cell-of-origin but with broader inclusivity than current genomic platforms, such as LymphGen. We hypothesized that CD5 - a surrogate marker of BCR activation - may effectively identify BCR-driven, non-GCB DLBCLs that are sensitive to BTKi therapy, and evaluated the extent to which CD5 protein expression and a transcriptionally defined CD5 gene signature could accurately identify BCR-activated DLBCLs with potential susceptibility to BTKi-based therapies. Methods: CD5 immunohistochemistry (IHC) was performed on a cohort of 406 diagnostic DLBCL samples, which were considered CD5+ if >=30% of lymphoma cells exhibited unequivocal membranous staining. A majority of DLBCL samples had available RNA-sequencing and targeted mutational sequencing data. A comparison of differentially expressed genes between CD5+ and CD5- DLBCLs was performed in order to construct a 60-gene CD5 signature (CD5sig), which was applied to large genomic DLBCL datasets, including pre-treatment biopsies from patients enrolled on PHOENIX (n = 584) to evaluate the utility of the CD5sig in identifying DLBCLs that benefitted from the addition of ibrutinib to R-CHOP. Results: Twenty-six of 406 DLBCLs were identified as CD5+ by IHC (6% of all DLBCLs; 12% of non-GCB DLBCLs). CD5 IHC+ DLBCLs were majority non-GCB cell-of-origin and were associated with inferior progression-free survival (PFS) to R-CHOP (50% 3-year PFS), compared with CD5 IHC- DLBCLs, consistent with previous reports. Gene set enrichment analysis revealed that CD5 IHC+ DLBCLs exhibited transcriptional features of BCR activation, and mutational analysis demonstrated that CD5 IHC+ DLBCLs were enriched for CD79B BCR-activating mutations known to correlate with BTKi sensitivity. Many CD5 IHC+ DLBCLs, however, lacked canonical BCR-activating mutations or were classified as “Other” by LymphGen. A CD5 gene signature (CD5sig; Figure 1A) was developed that recapitulated these findings in independent DLBCL datasets (NCI, Duke), where ~13% of non-GCB DLBCLs were classified as CD5sig+. Together, these results suggest that CD5 signature expression captures DLBCLs with both a genetic and non-genetic basis for BCR dependence. Supporting this notion, CD5sig+ DLBCL patients (< 60 years) derived a selective and striking event-free and overall survival advantage from the addition of ibrutinib to R-CHOP in the PHOENIX study ( Figure 1B), independent of LymphGen classification. Conclusions: We demonstrate that CD5 IHC and a novel CD5 gene signature identify high-risk, BCR-driven DLBCLs. Importantly, the CD5 signature also identifies DLBCL patients with a selective survival advantage to BTK inhibitor-based therapy, independent of LymphGen classification. In conclusion, the CD5 signature expands upon LymphGen classification as a biomarker of BTKi response by accurately identifying DLBCLs with both genetic and non-genetic bases for BTKi response. The CD5 signature and/or CD5 IHC should be prospectively evaluated in BTKi-based clinical trials for non-GCB DLBCLs.

A Single Center Real World Study of Outcome and Resistance of Bruton Tyrosine Kinase Inhibitors (BTKi) in Chinese Patients with Chronic Lymphocytic Leukeima/Small Lymphocytic Lymphoma

Introduction Acquired BTK/PLCG2 mutations remain to be the driver of Bruton Tyrosine Kinase inhibitor (BTKi) resistance. But the underlying mechanisms need to be further explored. In this study, we retrospectively analyzed clinical and biological characteristics of BTKi-treated CLL patients and report the outcome and resistance in our center (the First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital). Method 262 patients treated with single BTKis continuously were collected and follow up the outcome in our center. Progression-free survival (PFS) was defined as from BTKi initiation to disease progression on BTKi. Next-generation sequencing (NGS) and High sensitivity droplet digital PCR (ddPCR) acquired at treatment initiation /or at the time of disease progression were used to describe mutational landscape. Kaplan-Meier method and the log-rank test were used for analysis. Results A total of 262 patients were enrolled from January 2014 to March 2023, and the median age was 63 (range 28-88) years. Ibrutinib, Zanubrutinib, Orelabrutinib were administered in 55.3%,18.3% and 17.9% of patients respectively, in addition to 6 patients with Acalabrutinib and one with Loxo-305, among them 47.7% (125/262) received BTKi as first line treatment. With a median follow up of 27.3 months, 208 patients were in durable remission while 54 patients relapsed, the median exposure of BTKi was 26.8 (range, 1-73.8) sand 27.7 (range, 3-69.8) months respectively. The median PFS was 5.8 years (5.0-NA, 95% CI) for the whole cohort. Clinical and biological characteristics of both cohorts at initiation of BTKi treatment were described and compared in Table 1. Higher proportion of bulky disease (50.0% vs 23.5%), IGHV unmutated status (84.3% vs 50.5%), del(17p) (44.7% vs 12.9%), TP53 mutation (37.8% vs 15.2%), TP53 aberrations (62.5% vs 24.3%) and complex karyotype (40.5% vs 21.1%) were shown in the BTKi relapsed cohort as compared to responsive cohort. Inferior PFS was observed in patients with TP53 aberration vs without TP53 aberration ( 45.6 mos vs not reached, p<0.0001), unmutated IGHV vs mutated IGHV (56.2 mos vs not reached, p=0.0005), with del(17p) vs without del(17p) (36.1 mos vs not reached, p<0.0001), with complex karyotype and without complex karyotype (69.8 mos vs not reached, p=0.0401), bulky disease vs no bulky disease (45.6 mos vs 69.8 mos, p=0.0006) and elevated LDH vs normal LDH (66.5 mos vs not reached, p=0.0083). Moreover, patients with del(11q) or BTKi given as second or greater line showed a tendency of inferior PFS ( p= 0.1963, p= 0.0735, respectively). Regarding the relapsed cohort, 43 patients displayed CLL progression while 11 patients displayed Richter transformation (RT, including 1 Hodgkin lymphoma [HL]) , the median time from initiation to progression were 33.7 months and 9.5 months, respectively（p<0.0001). BTK/PLCG2 mutations were the most common mutation at the timepoint of disease progression. By integrating NGS and ddPCR results, 54.9% (28/51) relapsed patients acquired BTK/PLCG2 mutation. BTKC481S mutation was the dominant hotspot mutation in all kinds of BTKi relapsed cases. Other mutations at the C481 site included C481R, C481Y, C481F. However, BTKT474 mutation was only detected in Orelabrutinib-resistant cases (Figure 1). 6 patients presented with multi-hit mutations. Treatment after disease progression on BTKis is still challenging. In our relapsed cohort, the median PFS was 5.7 months and poorer in RT as compared with CLL progression (3.0 months vs 6.7 months, p= 0.0874). Venetoclax-based regimen might be an effective salvage therapy which could showed a benefit trend in PFS as compared to other post BTKi therapy (10.1 months vs 3.1 months, p= 0.1818). Conclusion In our real world study, patients with IGHV unmutated status, TP53 aberrations, bulky disease and elevated LDH showed inferior PFS. Acquired BTK/PLCG2 mutations remained to be key drivers of BTKis resistance and BTKC481S mutation was the dominant mutation, while BTKT474 mutation was only detected in Orelabrutinib-resistant patients. The prognosis was rather poor for relapsed patients especially for RTs, treatment strategy after disease progression remains to be optimized.