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Bruton tyrosine kinase inhibitors (BTKi) have transformed the treatment of B-cell malignancies, but intolerance has often led to their discontinuation. The phase 1/2 BRUIN study evaluated pirtobrutinib, a highly selective non-covalent (reversible) BTKi, in patients with R/R B-cell malignancies (NCT03740529). Pirtobrutinib was investigated in 127 patients with intolerance to at least one prior BTKi therapy in the absence of progressive disease. The most common adverse event (AE) leading to BTKi discontinuation was cardiac disorders (n=40, 31.5%), specifically atrial fibrillation (n=30, 23.6%). The median follow-up was 17.4 months and the median time on pirtobrutinib was 15.3 months. The most common reasons for pirtobrutinib discontinuation were progressive disease (26.8%), AE (10.2%), or death (5.5%). The most frequent treatment-emergent AEs were fatigue (39.4%) and neutropenia (37.0%). Among patients who discontinued a prior BTKi for a cardiac issue, 75% had no recurrence of their cardiac AE. No patient discontinued pirtobrutinib for the same AE that led to discontinuation of the prior BTKi. In 78 CLL/SLL and 21 MCL patients intolerant to prior BTKi, ORR to pirtobrutinib was 76.9% and 81.0%, respectively. Median PFS for CLL/SLL was 28.4 months and was not estimable for MCL. These results suggest that pirtobrutinib was safe, well-tolerated, and an efficacious option in patients with prior BTKi-intolerance.

Clinical bleeding events are reported here from 773 patients with B-cell malignancies receiving pirtobrutinib monotherapy from the phase 1/2 BRUIN study (ClinicalTrials.gov identifier: NCT03740529), either in the presence or absence of antithrombotic therapy (antithrombotic exposed [AT-E], n  = 216; antithrombotic nonexposed [AT-NE], n  = 557). Among the AT-E cohort, 51.9% received platelet aggregation inhibitors, 36.6% received direct factor Xa inhibitors, 18.5% received heparins, 5.6% received salicylic acid for indications other than platelet aggregation inhibition, and 2.3% received thrombolytics. Warfarin was not permitted. Any-grade bleeding/bruising events occurred in 97 patients (44.9%; 95% confidence interval [CI], 38.3-51.5) in the AT-E cohort and 181 patients (32.5%; 95% CI, 28.6-36.4) in the AT-NE cohort. Most bleeding/bruising events in both cohorts began within the first 6 months of treatment (AT-E: 65.4%; AT-NE: 72.5%). Contusion was the most common bleeding/bruising event in both cohorts (AT-E: 22.7%; AT-NE: 18.1%). Grade ≥3 bleeding/bruising events were reported in six patients (2.8%) in the AT-E cohort and 11 patients (2.0%) in the AT-NE cohort. Bleeding/bruising events requiring or prolonging hospitalization were reported in 2.3% and 1.6% of patients in the AT-E and AT-NE cohorts, respectively. No bleeding/bruising events led to pirtobrutinib dose reduction or permanent discontinuation in the AT-E cohort, and one patient (0.2%) in the AT-NE cohort experienced an event requiring dose reduction. These data support the safety of pirtobrutinib in patients requiring antithrombotic therapies., Competing Interests: NL reports research funding from Genentech, TG Therapeutics, BeiGene, AstraZeneca, AbbVie, MingSight, Eli Lilly and Company/Loxo@Lilly, Oncternal Therapeutics, and Octapharma, and consulting fees/honoraria from Genentech, Pharmacyclics, BeiGene, AstraZeneca, AbbVie, Adaptive Biotechnologies, Eli Lilly and Company/Loxo@Lilly, and Janssen. CST reports honoraria from Loxo@Lilly. JAW reports grants from the National Cancer Institute, Leukemia and Lymphoma Society, and CLL Global Society; consulting fees from AbbVie, AstraZeneca, BeiGene, Genentech, Janssen, Loxo@Lilly, Merck, Newave, and Pharmacyclics; and is on the advisory board of Gilead. AJA reports honoraria from Dr. Reddy's; is on advisory boards for Genentech, Eli Lilly and Company, Amgen, TG Therapeutics, Incyte, BeiGene, Janssen, Epizyme, and SeaGen; and reports research funding from Eli Lilly and Company, Incyte, and BeiGene. MLP reports participation on a data safety monitoring board or advisory board at Bristol‐Myers Squibb, Cellectar Biosciences, MustangBio, and Synthekine. PLZ reports membership on an entity's board of directors or advisory committee at AstraZeneca, Sandoz, Celltrion Healthcare, MSD, Secura Bio, Gilead, Janssen‐Cilag, Bristol‐Myers Squibb, Takeda, Roche, Servier Pharma, Kyowa Kirin, EUSA Pharma, Novartis, ADC Therapeutics, Incyte, and BeiGene; is on the speakers bureau of AstraZeneca, Celltrion Healthcare, MSD, Gilead, Janssen‐Cilag, Bristol‐Myers Squibb, Takeda, Roche, Servier Pharma, Kyowa Kirin, EUSA Pharma, Novartis, Incyte, and BeiGene; and has consultancy roles at MSD, EUSA Pharma, and Novartis. IWF reports consultancy roles at Genmab, BeiGene, Genentech, Secura Bio, Hutchison MediPharma, Kite Pharma, InnoCare Pharma, AbbVie, Novartis, Myeloid Therapeutics, Servier Pharma, Century Therapeutics, TG Therapeutics, and Vincerx Pharma. BF reports consultancy roles and membership on an entity's board of directors or advisory committee at BeiGene, AstraZeneca, ADC Therapeutics, AbbVie, Bristol‐Myers Squibb/Juno, Genentech, Genmab/AbbVie, Loxo@Lilly, and Pharmacyclics; and research funding from Genentech, Genmab/AbbVie, Loxo@Lilly, and Pharmacyclics. JBC reports research funding from Bristol‐Myers Squibb/Celgene, Novartis, Genentech, BioInvent, LAM Therapeutics, Takeda, ADC Therapeutics, AbbVie, and Loxo/Lilly; and consultancy roles at AstraZeneca, Janssen, BeiGene, and Loxo/Lilly. WJ reports research funding from Eli Lilly and Company; grants from AstraZeneca and BeiGene; and is on the advisory board for Eli Lilly and Company, AstraZeneca, and BeiGene. AK, HK, AC, and DET report full‐time employment with Loxo Oncology during the conduct of the study. ASR, RS, and LC report full‐time employment with Eli Lilly and Company during the conduct of the study., (© 2024 The Author(s). eJHaem published by British Society for Haematology and John Wiley & Sons Ltd.)

Abstract: Pirtobrutinib is a highly selective, noncovalent (reversible) Bruton tyrosine kinase inhibitor (BTKi). Patients with relapsed or refractory (R/R) chronic lymphocytic leukemia (CLL) were treated with fixed-duration pirtobrutinib plus venetoclax (PV) or pirtobrutinib plus venetoclax and rituximab (PVR) in this phase 1b trial. Prior covalent BTKi therapy was allowed, but not prior treatment with venetoclax. Patients were assigned to receive PV (n = 15) or PVR (n = 10) for 25 cycles. Most patients (68%) had received prior covalent BTKi therapy. At the data cutoff date, the median time on study was 27.0 months for PV and 23.3 months for PVR. Overall response rates were 93.3% (95% confidence interval [CI], 68.1-99.8) for PV and 100% (95% CI, 69.2-100.0) for PVR, with 10 complete responses (PV: 7; PVR: 3). After 12 cycles of treatment, 85.7% (95% CI, 57.2-98.2) of PV and 90.0% (95% CI, 55.5-99.7) of PVR patients achieved undetectable minimal residual disease (<10-4) in peripheral blood. Progression-free survival at 18 months was 92.9% (95% CI, 59.1-99.0) for PV patients and 80.0% (95% CI, 40.9-94.6) for PVR patients. No dose-limiting toxicities were observed during the 5-week assessment period. The most common grade ≥3 adverse events (AEs) for all patients included neutropenia (52%) and anemia (16%). AEs led to dose reduction in 3 patients and discontinuation in 2. In conclusion, fixed-duration PV or PVR was well tolerated and had promising efficacy in patients with R/R CLL, including patients previously treated with a covalent BTKi. This trial was registered at www.clinicaltrials.gov as #NCT03740529., (© 2024 American Society of Hematology. Published by Elsevier Inc. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Abstract: Chronic lymphocytic leukemia (CLL) progression during Bruton tyrosine kinase (BTK) inhibitor treatment is typically characterized by emergent B-cell receptor pathway mutations. Using peripheral blood samples from patients with relapsed/refractory CLL in ELEVATE-RR (NCT02477696; median 2 prior therapies), we report clonal evolution data for patients progressing on acalabrutinib or ibrutinib (median follow-up, 41 months). Paired (baseline and progression) samples were available for 47 (excluding 1 Richter) acalabrutinib-treated and 30 (excluding 6 Richter) ibrutinib-treated patients. At progression, emergent BTK mutations were observed in 31 acalabrutinib-treated (66%) and 11 ibrutinib-treated patients (37%; median variant allele fraction [VAF], 16.1% vs 15.6%, respectively). BTK C481S mutations were most common in both groups; T474I (n = 9; 8 co-occurring with C481) and the novel E41V mutation within the pleckstrin homology domain of BTK (n = 1) occurred with acalabrutinib, whereas neither mutation occurred with ibrutinib. L528W and A428D comutations presented in 1 ibrutinib-treated patient. Preexisting TP53 mutations were present in 25 acalabrutinib-treated (53.2%) and 16 ibrutinib-treated patients (53.3%) at screening. Emergent TP53 mutations occurred with acalabrutinib and ibrutinib (13% vs 7%; median VAF, 6.0% vs 37.3%, respectively). Six acalabrutinib-treated patients and 1 ibrutinib-treated patient had emergent TP53/BTK comutations. Emergent PLCG2 mutations occurred in 3 acalabrutinib-treated (6%) and 6 ibrutinib-treated patients (20%). One acalabrutinib-treated patient and 4 ibrutinib-treated patients had emergent BTK/PLCG2 comutations. Although common BTK C481 mutations were observed with both treatments, patterns of mutation and comutation frequency, mutation VAF, and uncommon BTK variants varied with acalabrutinib (T474I and E41V) and ibrutinib (L528W and A428D) in this patient population. The trial was registered at www.clinicaltrials.gov as #NCT02477696., (© 2024 American Society of Hematology. Published by Elsevier Inc. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Background: Richter transformation usually presents as an aggressive diffuse large B-cell lymphoma, occurs in up to 10% of patients with chronic lymphocytic leukaemia, has no approved therapies, and is associated with a poor prognosis. Pirtobrutinib has shown promising efficacy and tolerability in patients with relapsed or refractory B-cell malignancies, including those who progress on covalent Bruton tyrosine kinase (BTK) inhibitors. This study aims to report the safety and activity of pirtobrutinib monotherapy in a subgroup of patients with Richter transformation from the multicentre, open-label, phase 1/2 BRUIN study., Methods: This analysis included adult patients (aged ≥18 years) with histologically confirmed Richter transformation, an Eastern Cooperative Oncology Group performance status score of 0-2, and no limit of previous therapies, with patients receiving first-line treatment added in a protocol amendment (version 9.0, Dec 15, 2021). Pirtobrutinib 200 mg was administered orally once a day in 28-day cycles. The primary endpoint of phase 1 of the BRUIN trial as a whole, which has been previously reported, was to establish the recommended phase 2 dose for pirtobrutinib monotherapy and the phase 2 primary endpoint was overall response rate. Safety and activity were measured in all patients who received at least one dose of pirtobrutinib monotherapy. This BRUIN phase 1/2 trial was registered with ClinicalTrials.gov and is closed to enrolment (NCT03740529)., Findings: Between Dec 26, 2019, and July 22, 2022, 82 patients were enrolled, of whom five were enrolled during phase 1 and 77 during phase 2. All but one patient received a starting dose of 200 mg pirtobrutinib once a day as the recommended phase 2 dose. The remaining patient received 150 mg pirtobrutinib once a day, which was not escalated to 200 mg. The median age of patients was 67 years (IQR 59-72). 55 (67%) of 82 patients were male and 27 (33%) were female. Most patients were White (65 [79%] of 82). 74 (90%) of 82 patients received at least one previous Richter transformation-directed therapy. Most patients (61 [74%] of 82) had received previous covalent BTK inhibitor therapy for chronic lymphocytic leukaemia or Richter transformation. The overall response rate was 50·0% (95% CI 38·7-61·3). 11 (13%) of 82 patients had a complete response and 30 (37%) of 82 patients had a partial response. Eight patients with ongoing response electively discontinued pirtobrutinib to undergo stem-cell transplantation. The most common grade 3 or worse adverse event was neutropenia (n=19). There were no treatment-related deaths., Interpretation: Pirtobrutinib shows promising safety and activity among patients with Richter transformation, most of whom received previous Richter transformation-directed therapy, including covalent BTK inhibitors. These data suggest that further investigation is warranted of pirtobrutinib as a treatment option for patients with relapsed or refractory Richter transformation after treatment with a covalent BTK inhibitor., Funding: Loxo Oncology., Competing Interests: Declaration of interests WGW reports research funding from Numab Therapeutics, Loxo Oncology–Lilly, Janssens Biotech, NIH P30 CA016672/MDACC Cancer Center Support Grant, GlaxoSmithKline, AbbVie, Cyclacel, Nurix Therapeutics, Juno Therapeutics, Bristol Myers Squibb (Juno & Celgene), AstraZeneca–Acerta Pharma Miragen, Oncternal Therapeutics, Janssens Biotech, Accutar Biotechnology, Sunesis, KITE Pharma, Gilead Sciences, Genentech, Pharmacyclics, GlaxoSmithKline–Novartis; consultancy fees from AbbVie, Cyclacel Nurix Therapeutics, Bristol Myers Squibb (Juno & Celgene), AstraZeneca–Acerta Pharma; a non-relevant financial relationship with the National Comprehensive Cancer Network; support from the National Institutes of Health and National Cancer Institute under award number P30 CA016672; and use of MDACC Cancer Center Support Grant shared resources. NNS reports consultancy fees from Umoja, Janssen, Bristol Myers Squibb–Juno, LOXO Oncology–Lilly, TG therapeutic, Novartis, Seattle Genetics, Gilead–Kite, Incyte, AbbVie, Lilly Oncology, and Miltenyi Biotec; research funding from Miltenyi Biotec and Lilly Oncology; having stock options in a privately-held company with Tundra Therapeutics; and travel support from Epizyme and Miltenyi Biotec. CYC reports consultancy fees, honoraria, and having an advisory role for Roche, Janssen, Gilead, AstraZenecca, Eli Lilly, BeiGene, AbbVie, Menarini, Daizai, and Genmab, and research funding from Roche, MSD, Eli Lilly, Bristol Myers Squibb, and AbbVie. DL reports consultancy fees from Kite, BeiGene, Roche, Eli Lilly, and Janssen and membership on an entity's board of directors or advisory committees with Kite, BeiGene, Roche, Eli Lilly, and Janssen. MSH reports consultancy fees and honoraria from Pharmacyclics. CCC reports consultancy fees from LOXO Oncology–Eli Lilly, BeiGene, AstraZeneca, Genentech, AbbVie, Octapharma, Allogene, Janssen, TG Therapeutics, MEI Pharma, and Mingsight; honoraria from LOXO Oncology–Eli Lilly, BeiGene, AstraZeneca, Genentech, AbbVie; research funding paid to an institution from LOXO Oncology–Eli Lilly, AbbVie, and CarnaBio; membership on an entity's board of directors or advisory committees with BeiGene, AstraZeneca, Genentech, and AbbVie; being an equity holder in a publicly-traded company with Bluebird Bio, Geron, and Pfizer; and receiving travel support from LOXO Oncology–Eli Lilly. NL reports consultancy fees from Genentech, Pharmacyclics, BeiGene, AstraZeneca, AbbVie, Adaptive Biotechnologies, Janssen, and research funding from Genentech, TG Therapeutics, BeiGene, AstraZeneca, AbbVie, MingSight, LOXO Oncology–Eli Lilly, Oncternal, and Octapharma. SM reports consultancy fees from AstraZeneca, Juno–Bristol Myers Squibb, AbbVie, Genentech, Janssen Pharmaceuticals, BeiGene; membership on a board of directors or advisory committee with AstraZeneca, Juno–Bristol Myers Squibb, Janssen Pharmaceuticals, Eli Lilly, Loxo Oncology, and BeiGene; research funding from AstraZeneca, Juno–Bristol Myers Squibb, AbbVie, Janssen Pharmaceuticals, Eli Lilly–Loxo Oncology, BeiGene; and speakers bureau with AstraZeneca, Eli Lilly–Loxo Oncology, and BeiGene. DJ reports research funding from Seagen, Trillium Pharmaceuticals, Regeneron Pharmaceuticals, MEI Pharma, Loxo Oncology, Debio Pharma, ATARA Biotherapeutics, AstraZeneca and membership on a board of directors or advisory committees with Affimed and Daiichi Sankyo. TM reports consultancy fees from BeiGene, Alexion, Sobi, Roche, AstraZeneca, Janssen, and AbbVie; honoraria from BeiGene, Alexion, Sobi, Roche, AstraZeneca, Janssen, and AbbVie; membership on a board of directors or advisory committees on BeiGene, Alexion, Sobi, Roche, AstraZeneca, Janssen, Abbvie; research Funding from Janssen, AbbVie; and speakers bureau for BeiGene, Alexion, Sobi, Roche, AstraZeneca, Janssen, and AbbVie. YW reports research funding from Incyte, InnoCare, LOXO Oncology, Eli Lilly, MorphoSys, Novartis, Genentech, Genmab, and AbbVie; membership on an advisory board with Eli Lilly, LOXO Oncology, TG Therapeutics, Incyte, InnoCare, Kite, Jansen, BeiGene, AstraZeneca, and Genmab; consultancy fees from Innocare and AbbVie; and honoraria from Kite. TAE reports membership on an entity's Board of Directors or advisory committees from Loxo Oncology, Incyte, BeiGene, AstraZeneca, KITE, AbbVie, Roche, Gilead, Secura Bio; speakers bureau from Loxo Oncology, Eli Lilly, Incyte, BeiGene, AstraZeneca, KITE, AbbVie, Loxo Oncology, Roche, Medscape, Janssen, Gilead, PeerView; research funding from BeiGene and AstraZeneca; consultancy fees from Eli Lilly, Incyte, Beigene, Autolus, AstraZeneca, KITE, AbbVie, Loxo Oncology, Roche, Janssen, and Gilead; and honoraria from Eli Lilly, BeiGene, AstraZeneca, KITE, AbbVie, Loxo Oncology, Roche, Janssen, and Gilead. JMR reports consultancy fees from Pharmacyclics, Jannsen, Genentech, GenMab, AstraZeneca, Morphosys, ADC Therapeutics, Epizyme, BeiGene, and AbbVie; research funding from Pharmacyclics, Velosbio, Loxo Oncology, Acerta, Oncternal Pharmaceuticals, Epizyme, and AbbVie; and honoraria from SeaGen. MM reports consultancy from Bayer, ADC therapeutics, Epizyme, Genentech, F Hoffmann-La Roche, and Incyte; research funding from BeiGene, Janssen, F Hoffmann-La Roche– Genentech, Celgene–Bristol Myers Squibb, and Incyte; and speakers bureau with ADC therapeutics, BeiGene, and Kite–Gilead. CT reports honoraria from Loxo Oncolgy. WJ reports consultancy fees from AbbVie, AstraZeneca, BeiGene, Eli Lilly, Pfizer, Roche, SOBI, and Takeda and research funding from AbbVie, AstraZeneca, Bayer, BeiGene, Celgene, Janssen, Eli Lilly, Roche, SOBIm, and Takeda. KI reports honoraria from Eli Lilly, SymBio Pharmaceuticals, Meiji Seika, Nihon Kayaku, Takeda, AstraZeneca, Janssen, Genmab, MSD, Pfizer, AbbVie, Ono Pharmaceuticals, Daiichi Sankyo, Novartis, Bristol Myers Squibb, Chugai Pharma, and Kyowa Kirin; consultancy fees from Takeda, AstraZeneca, Genmab, AbbVie, Otsuka, Eisai, Ono Pharmaceuticals, Nippon Shinyaku, Mitsubishi Tanabe Pharma, and Zenyaku Kogyo; and research funding from AstraZeneca, Genmab, MSD, Pfizer, AbbVie, Otsuka, Eisai, Regeneron, Loxo Oncology, BeiGene, Daiichi Sankyo, Yakult, Novartis, Bristol Myers Squibb, Incyte, Astellas Amgen, Chugai Pharma, Kyowa Kirin. AA reports membership on a board of directors or advisory committees with Genentech, Eli Lilly and Company, Amgen, TG Therapeutics, Incyte, BeiGene, Epizyme, Janssen, and SeaGen; research funding from Eli Lilly, Incyte, and BeiGene; and honoraria from Dr Reddy. MP reports consulting fees from Kura, Accutar, Mitsubishi; participating on a data safety monitoring board or advisory board with lema, Nurix, Daiichi, Kura, and Janssen; leadership with ION Pharma; honoraria from Janssen Oncology; and participating in a consulting or advisory role with Olema Pharmaceuticals, Daiichi Sankyo–UCB Japan, Kura Oncology, Accutar Biotech, and Kura. JFS reports honoraria from Hoffmann-La Roche, AbbVie, AstraZeneca, Janssen, Bristol Myers Squibb, Gilead, and BeiGene; consultancy fees from Hoffmann-La Roche, TG Therapeutics, Bristol Myers Squibb; participating on a data safety monitoring board or advisory board with Genor Bio, Hoffmann-La Roche, AbbVie, AstraZeneca, Janssen, Bristol Myers Squibb, Gilead, and BeiGene; speakers bureau with Hoffmann-La Roche, AbbVie, and BeiGene; and research funding from F Hoffmann-La Roche and AbbVie. JAW reports consultancy from Newave, Loxo Oncology, BeiGene, AstraZeneca, AbbVie, Janssen, and Pharmacyclics and research funding from Schrodinger, Morphosys, Karyopharm, Janssen, and Pharmacyclics. PAT reports consultancy and honoraria from AbbVie, Adaptive Biotechnologies, Ascentage AstraZeneca, BeiGene, Genentech, Genmab, Janssen, Lilly, Merck, Pharmacyclics; speakers bureau from AbbVie, Adaptive Biotechnologies, AstraZeneca, Janssen, and Merck; research funding from AbbVie, Pharmacyclics, Genentech, Lilly, and Adaptive Biotechnologies; and travel support from Merck. PA is a current employee of and equity holder in Eli Lilly. CH reports being an equity holder in Eli Lilly and Foundation Medicine and travel support from Eli Lilly. SCM reports current employment with, being an equity holder in, and travel support from Eli Lilly. NM reports being a current equity holder in Eli Lilly and current employment with Loxo Oncology. BN, CW, BCN, and DET reports current employment with and current equity holder in Eli Lilly. ASR reports current employment with and being equity holder in Eli Lilly and consultancy work with Telios Pharma. HL reports current employment with Loxo Oncology. LER reports serving as a consultant for AbbVie, Ascentage, AstraZeneca, BeiGene, Janssen, Loxo Oncology, Pharmacyclics, Pfizer, and TG Therapeutics; membership of a data safety monitoring committee for Ascentage; serving as a CME speaker for DAVA, Curio, Medscape, and PeerView; holding minority ownership interest in Abbott Laboratories; having received travel support from LOXO Oncology; and having received research funding (paid to the institution) from Adaptive Biotechnologies, AstraZeneca, Genentech, AbbVie, Pfizer, Loxo Oncology, Aptose Biosciences, Dren Bio, and Qilu Puget Sound Biotherapeutics. PG reports consultancy, fees, honoraria, and research funding from Janssen, Eli Lilly–Loxo Oncology, MSD, Roche, AbbVie, BMS, BeiGene, and AstraZeneca., (Copyright © 2024 Elsevier Ltd. All rights reserved, including those for text and data mining, AI training, and similar technologies.)

Patients with chronic lymphocytic leukemia (CLL) respond well to initial treatment with the Bcell lymphoma 2 (BCL2) inhibitor venetoclax. Upon relapse, they often retain sensitivity to BCL2 targeting, but durability of response remains a concern. We hypothesize that targeting both BCL2 and B-cell lymphoma-extra large (BCLXL) will be a successful strategy to treat CLL, including for patients who relapse on venetoclax. To test this hypothesis, we conducted a pre-clinical investigation of LP-118, a highly potent inhibitor of BCL2 with moderate BCLXL inhibition to minimize platelet toxicity. This study demonstrated that LP-118 induces efficient BAK activation, cytochrome C release, and apoptosis in both venetoclax naïve and resistant CLL cells. Significantly, LP-118 is effective in cell lines expressing the BCL2 G101V mutation and in cells expressing BCLXL but lacking BCL2 dependence. Using an immunocompetent mouse model, Eμ-TCL1, LP-118 demonstrates low platelet toxicity, which hampered earlier BCLXL inhibitors. Finally, LP-118 in the RS4;11 and OSU-CLL xenograft models results in decreases in tumor burden and survival advantage, respectively. These results provide a mechanistic rationale for the evaluation of LP-118 for the treatment of venetoclax responsive and relapsed CLL.

Abstract: Before targeted therapies, patients with higher-risk chronic lymphocytic leukemia (CLL), defined as del(17p) and/or TP53 mutation (TP53m), unmutated immunoglobulin heavy chain variable region genes (uIGHV), or complex karyotype (CK), had poorer prognosis with chemoimmunotherapy. Bruton tyrosine kinase inhibitors (BTKis) have demonstrated benefit in higher-risk patient populations with CLL in individual trials. To better understand the impact of the second-generation BTKi acalabrutinib, we pooled data from 5 prospective clinical studies of acalabrutinib as monotherapy or in combination with obinutuzumab (ACE-CL-001, ACE-CL-003, ELEVATE-TN, ELEVATE-RR, and ASCEND) in patients with higher-risk CLL in treatment-naive (TN) or relapsed/refractory (R/R) cohorts. A total of 808 patients were included (TN cohort, n = 320; R/R cohort, n = 488). Median follow-up was 59.1 months (TN cohort) and 44.3 months (R/R cohort); 51.3% and 26.8% of patients in the TN and R/R cohorts, respectively, remained on treatment at last follow-up. In the del(17p)/TP53m, uIGHV, and CK subgroups in the TN cohort, median progression-free survival (PFS) and median overall survival (OS) were not reached (NR). In the del(17p)/TP53m, uIGHV, and CK subgroups in the R/R cohort, median PFS was 38.6 months, 46.9 months, and 38.6 months, respectively, and median OS was 60.6 months, NR, and NR, respectively. The safety profile of acalabrutinib-based therapy in this population was consistent with the known safety profile of acalabrutinib in a broad CLL population. Our analysis demonstrates long-term benefit of acalabrutinib-based regimens in patients with higher-risk CLL, regardless of line of therapy., (© 2024 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Introduction: Therapeutic antibodies have become a major strategy to treat oncologic diseases. For chronic lymphocytic leukemia, antibodies against CD20 are used to target and elicit cytotoxic responses against malignant B cells. However, efficacy is often compromised due to a suppressive microenvironment that interferes with cellular immune responses. To overcome this suppression, agonists of pattern recognition receptors have been studied which promote direct cytotoxicity or elicit anti-tumoral immune responses. NOD2 is an intracellular pattern recognition receptor that participates in the detection of peptidoglycan, a key component of bacterial cell walls. This detection then mediates the activation of multiple signaling pathways in myeloid cells. Although several NOD2 agonists are being used worldwide, the potential benefit of these agents in the context of antibody therapy has not been explored., Methods: Primary cells from healthy-donor volunteers (PBMCs, monocytes) or CLL patients (monocytes) were treated with versus without the NOD2 agonist L18-MDP, then antibody-mediated responses were assessed. In vivo, the Eµ-TCL1 mouse model of CLL was used to test the effects of L18-MDP treatment alone and in combination with anti-CD20 antibody., Results: Treatment of peripheral blood mononuclear cells with L18-MDP led to activation of monocytes from both healthy donors and CLL patients. In addition, there was an upregulation of activating FcγR in monocytes and a subsequent increase in antibody-mediated phagocytosis. This effect required the NF-κB and p38 signaling pathways. Treatment with L18-MDP plus anti-CD20 antibody in the Eµ-TCL model of CLL led to a significant reduction of CLL load, as well as to phenotypic changes in splenic monocytes and macrophages., Conclusions: Taken together, these results suggest that NOD2 agonists help overturn the suppression of myeloid cells, and may improve the efficacy of antibody therapy for CLL., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Merchand-Reyes, Bull, Santhanam, Valencia-Pena, Murugesan, Chordia, Mo, Robledo-Avila, Ruiz-Rosado, Carson, Byrd, Woyach, Tridandapani and Butchar.)

Purpose: Outcomes for Richter transformation (RT) are poor with current therapies. The efficacy and safety of anti-CD19 chimeric antigen receptor T-cell therapy (CAR-T) for RT are not established., Methods: We performed an international multicenter retrospective study of patients with RT who received CAR-T. Patient, disease, and treatment characteristics were summarized using descriptive statistics, and modeling analyses were used to determine association with progression-free survival (PFS) and overall survival (OS). PFS and OS were estimated from the date of CAR-T infusion., Results: Sixty-nine patients were identified. The median age at CAR-T infusion was 64 years (range, 27-80). Patients had a median of four (range, 1-15) previous lines of therapy for CLL and/or RT, including previous Bruton tyrosine kinase inhibitor and/or BCL2 inhibitor therapy in 58 (84%) patients. The CAR-T product administered was axicabtagene ciloleucel in 44 patients (64%), tisagenlecleucel in 17 patients (25%), lisocabtagene maraleucel in seven patients (10%), and brexucabtagene autoleucel in one patient (1%). Eleven patients (16%) and 25 patients (37%) experienced grade ≥3 cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome, respectively. The overall response rate was 63%, with 46% attaining a complete response (CR). After a median follow-up of 24 months, the median PFS was 4.7 months (95% CI, 2.0 to 6.9); the 2-year PFS was 29% (95% CI, 18 to 41). The median OS was 8.5 months (95% CI, 5.1 to 25.4); the 2-year OS was 38% (95% CI, 26 to 50). The median duration of response was 27.6 months (95% CI, 14.5 to not reached) for patients achieving CR., Conclusion: CAR-T demonstrates clinical efficacy for patients with RT.

Introduction: Pirtobrutinib, a highly selective, noncovalent (reversible) Bruton tyrosine kinase inhibitor, has demonstrated promising efficacy in B-cell malignancies and is associated with low rates of discontinuation and dose reduction. Pirtobrutinib is administered until disease progression or toxicity, necessitating an understanding of the safety profile in patients with extended treatment., Methods: Here we report the safety of pirtobrutinib in patients with relapsed/refractory B-cell malignancies with extended (≥12 months) drug exposure from the BRUIN trial. Assessments included median time-to-first-occurrence of adverse events (AEs), dose reductions, and discontinuations due to treatment-emergent AEs (TEAEs) and select AEs of interest (AESIs)., Results: Of 773 patients enrolled, 326 (42%) received treatment for ≥12 months. In the extended exposure cohort, the median time-on-treatment was 19 months. The most common all-cause TEAEs were fatigue (32%) and diarrhea (31%). TEAEs leading to dose reduction occurred in 23 (7%) and discontinuations in 11 (3%) extended exposure patients. One patient had a fatal treatment-related AE (COVID-19 pneumonia). Infections (73.0%) were the most common AESI with a median time-to-first-occurrence of 7.4 months. Majority of TEAEs and AESIs occurred during the first year of therapy., Conclusions: Pirtobrutinib therapy continues to demonstrate an excellent safety profile amenable to long-term administration without evidence of new or worsening toxicity signals., (© 2024 The Author(s). Published by S. Karger AG, Basel.)

Inhibitors of Bruton's tyrosine kinase (BTK) are among the most widely used therapies for chronic lymphocytic leukemia (CLL) and established a new expectation for efficacy and safety in the treatment of this disease. Currently there are 3 covalent inhibitors of BTK approved for the treatment of CLL: ibrutinib, acalabrutinib, and zanubrutinib. The first-in-class covalent BTK inhibitor is ibrutinib, which as monotherapy has excellent efficacy in the front-line setting with a 7-year progression free survival (PFS) of 59%. Ibrutinib-based therapies have also demonstrated superiority over standard chemoimmunotherapy in the front-line and the relapsed/refractory setting. Acalabrutinib is a second-generation BTK inhibitor that has higher selectivity to BTK. Acalabrutinib has efficacy in both frontline and relapsed CLL and is associated with a decreased incidence of atrial fibrillation and hypertension when compared to ibrutinib. Like acalabrutinib, zanubrutinib was designed to be more selective for BTK than ibrutinib and to maximize BTK inhibition in tissues. Zanubrutinib has demonstrated clinical efficacy in first line and relapsed/refractory setting. These agents are indicated as monotherapy, with dosing until disease progression or intolerable toxicity, and are mainly differentiated by safety profile, although efficacy differences may exist as well. Combination with CD20 monoclonal antibodies and/or BCL2 inhibitors are alternative options for use. Here we will review efficacy and safety considerations with these agents., Competing Interests: Disclosure JAW: Consulting: Abbvie, AstraZeneca, Beigene, Genentech, Janssen, Loxo/Lilly, Merck, Newave, Pharmacyclics. The other authors have stated that they have no conflicts of interest., (Copyright © 2024. Published by Elsevier Inc.)

Abstract: Patients with chronic lymphocytic leukemia (CLL) who develop Richter transformation (RT) have a poor prognosis when treated with chemoimmunotherapy regimens used for de novo diffuse large B-cell lymphoma. Venetoclax, a BCL2 inhibitor, has single-agent efficacy in patients with RT and is potentially synergistic with chemoimmunotherapy. In this multicenter, retrospective study, we evaluated 62 patients with RT who received venetoclax-based treatment outside of a clinical trial, in combination with a Bruton tyrosine kinase inhibitor (BTKi; n=28), rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone (R-CHOP) (n=13), or intensive chemoimmunotherapy other than R-CHOP (n=21). The best overall and complete response rates were 36%/25%, 54%/46%, and 52%/38%, respectively. The median progression-free and overall survival estimates for the same treatment groups were 4.9/14.3 months, 14.9 months/not reached, and 3.3/9 months, respectively. CLL with del(17p) was associated with a lower complete response rate in the total cohort (odds ratio [OR] 0.15; 95% confidence interval [CI] 0.04-0.6; p=0.01) and venetoclax-naïve subgroup (OR 0.13; 95%CI 0.02-0.66; p=0.01). TP53 mutated CLL was associated with a lower complete response rate (OR 0.15; 95%CI 0.03-0.74; p=0.02) and shorter progression-free survival (hazard ratio 3.1; 95%CI 1.21-7.95; p=0.02) only in venetoclax-naïve subgroup. No other clinical or baseline characteristics, including prior venetoclax treatment for CLL, showed statistically significant association with outcomes. Grade 3-4 neutropenia and thrombocytopenia events were most frequent with intensive chemoimmunotherapy + venetoclax; grade 3-4 infection rates were similar across treatment groups. In this difficult-to-treat RT patient population, venetoclax-based combination regimens achieved high response rates, with durable remission and survival observed in a subset of patients., (© 2024 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Abstract: A041202 (NCT01886872) is a phase 3 study comparing bendamustine plus rituximab (BR) with ibrutinib and the combination of ibrutinib plus rituximab (IR) in previously untreated older patients with chronic lymphocytic leukemia (CLL). The initial results showed that ibrutinib-containing regimens had superior progression-free survival (PFS) and rituximab did not add additional benefits. Here we present an updated analysis. With a median follow-up of 55 months, the median PFS was 44 months (95% confidence interval [CI], 38-54) for BR and not yet reached in either ibrutinib-containing arm. The 48-month PFS estimates were 47%, 76%, and 76% for BR, ibrutinib, and IR, respectively. The benefit of ibrutinib regimens over chemoimmunotherapy was consistent across subgroups of patients defined by TP53 abnormalities, del(11q), complex karyotype, and immunoglobulin heavy chain variable region (IGHV). No significant interaction effects were observed between the treatment arm and del(11q), the complex karyotype, or IGHV. However, a greater difference in PFS was observed among the patients with TP53 abnormalities. There was no difference in the overall survival. Notable adverse events with ibrutinib included atrial fibrillation (afib) and hypertension. Afib was observed in 11 patients (pts) on BR (3%) and 67 pts on ibrutinib (18%). All-grade hypertension was observed in 95 pts on BR (27%) and 263 pts on ibrutinib (55%). These data show that ibrutinib regimens prolong PFS compared with BR for older patients with treatment-naïve CLL. These benefits were observed across subgroups, including high-risk groups. Strikingly, within the ibrutinib arms, there was no inferior PFS for patients with abnormalities in TP53, the highest risk feature observed in CLL. These data continue to demonstrate the efficacy of ibrutinib in treatment-naïve CLL.

Chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL) are essentially different manifestations of the same disease that are similarly managed. A number of molecular and cytogenetic variables with prognostic implications have been identified. Undetectable minimal residual disease at the end of treatment with chemoimmunotherapy or venetoclax-based combination regimens is an independent predictor of improved survival among patients with previously untreated or relapsed/refractory CLL/SLL. The selection of treatment is based on the disease stage, presence or absence of del(17p) or TP53 mutation, immunoglobulin heavy chain variable region mutation status, patient age, performance status, comorbid conditions, and the agent's toxicity profile. This manuscript discusses the recommendations outlined in the NCCN Guidelines for the diagnosis and management of patients with CLL/SLL.

Aberrant signal transduction through the B cell receptor (BCR) plays a critical role in the pathogenesis of chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). BCR-dependent signaling is necessary for the growth and survival of neoplastic cells, making inhibition of down-stream pathways a logical therapeutic strategy. Indeed, selective inhibitors against Bruton's tyrosine kinase (BTK) and phosphoinositide 3-kinase (PI3K) have been shown to induce high rates of response in CLL and other B cell lymphomas. In particular, the development of BTK inhibitors revolutionized the treatment approach to CLL, demonstrating long-term efficacy. While BTK inhibitors are widely used for multiple lines of treatment, PI3K inhibitors are much less commonly utilized, mainly due to toxicities. CLL remains an incurable disease and effective treatment options after relapse or development of TKI resistance are greatly needed. This review provides an overview of BCR signaling, a summary of the current therapeutic landscape, and a discussion of the ongoing trials targeting BCR-associated kinases., Competing Interests: Declaration of competing interest JTP has no conflicts of interest to disclose. JAW consults for Abbvie, AstraZeneca, Beigene, Genentech, Janssen, Loxo/Lilly, Merck, Newave, and Pharmacyclics, and research funding from Abbvie, Janssen, and Schrodinger., (Copyright © 2024. Published by Elsevier Inc.)

Acute myeloid leukemia (AML) is a highly aggressive hematologic cancer with poor survival across a broad range of molecular subtypes. Development of efficacious and well-tolerable therapies encompassing the range of mutations that can arise in AML remains an unmet need. The bromo- and extra-terminal domain (BET) family of proteins represents an attractive therapeutic target in AML due to their crucial roles in many cellular functions, regardless of any specific mutation. Many BET inhibitors (BETi) are currently in pre-clinical and early clinical development, but acquisition of resistance continues to remain an obstacle for the drug class. Novel methods to circumvent this development of resistance could be instrumental for the future use of BET inhibitors in AML, both as monotherapy and in combination. To date, many investigations into possible drug combinations of BETi with CDK inhibitors have focused on CDK9, which has a known physical and functional interaction with the BET protein BRD4. Therefore, we wished to investigate possible synergy and additive effects between inhibitors of these targets in AML. Here, we describe combination therapy with the multi-CDK inhibitor dinaciclib and the BETi PLX51107 in pre-clinical models of AML. Dinaciclib and PLX51107 demonstrate additive effects in AML cell lines, primary AML samples, and in vivo. Further, we demonstrate novel activity of dinaciclib through inhibition of the canonical/β-catenin dependent Wnt signaling pathway, a known resistance mechanism to BETi in AML. We show dinaciclib inhibits Wnt signaling at multiple levels, including downregulation of β-catenin, the Wnt co-receptor LRP6, as well as many Wnt pathway components and targets. Moreover, dinaciclib sensitivity remains unaffected in a setting of BET resistance, demonstrating similar inhibitory effects on Wnt signaling when compared to BET-sensitive cells. Ultimately, our results demonstrate rationale for combination CDKi and BETi in AML. In addition, our novel finding of Wnt signaling inhibition could have potential implications in other cancers where Wnt signaling is dysregulated and demonstrates one possible approach to circumvent development of BET resistance in AML., (© 2024. The Author(s).)

Genetic and gene expression heterogeneity is an essential hallmark of many tumors, allowing the cancer to evolve and to develop resistance to treatment. Currently, the most commonly used data types for studying such heterogeneity are bulk tumor/normal whole-genome or whole-exome sequencing (WGS, WES); and single-cell RNA sequencing (scRNA-seq), respectively. However, tools are currently lacking to link genomic tumor subclonality with transcriptomic heterogeneity by integrating genomic and single-cell transcriptomic data collected from the same tumor. To address this gap, we developed scBayes, a Bayesian probabilistic framework that uses tumor subclonal structure inferred from bulk DNA sequencing data to determine the subclonal identity of cells from single-cell gene expression (scRNA-seq) measurements. Grouping together cells representing the same genetically defined tumor subclones allows comparison of gene expression across different subclones, or investigation of gene expression changes within the same subclone across time (i.e., progression, treatment response, or relapse) or space (i.e., at multiple metastatic sites and organs). We used simulated data sets, in silico synthetic data sets, as well as biological data sets generated from cancer samples to extensively characterize and validate the performance of our method, as well as to show improvements over existing methods. We show the validity and utility of our approach by applying it to published data sets and recapitulating the findings, as well as arriving at novel insights into cancer subclonal expression behavior in our own data sets. We further show that our method is applicable to a wide range of single-cell sequencing technologies including single-cell DNA sequencing as well as Smart-seq and 10x Genomics scRNA-seq protocols., (© 2024 Qiao et al.; Published by Cold Spring Harbor Laboratory Press.)

Nemtabrutinib is an orally bioavailable, reversible inhibitor of Bruton tyrosine kinase (BTK) and C481S mutant BTK. We evaluated the safety, pharmacology, and antitumor activity of nemtabrutinib in relapsed/refractory hematologic malignancies. Forty-eight patients with chronic lymphocytic leukemia (CLL), B-cell non-Hodgkin lymphoma (NHL), or Waldenström macroglobulinemia (WM), relapsed/refractory after ≥2 prior therapies were enrolled in the open-label, single-arm, phase I MK-1026-001 study (NCT03162536) to receive nemtabrutinib 5 to 75 mg once daily in 28-day cycles. Dose finding progressed using a 3 + 3 dose escalation design. Primary endpoints were safety and the recommended phase II dose (RP2D). Among 47 treated patients, 29 had CLL, 17 had NHL, and 1 had WM. Grade ≥3 treatment-emergent adverse events occurred in 37 (89%), most commonly neutropenia (11; 23.4%), febrile neutropenia (7; 14.9%), and pneumonia (7; 14.9%). The RP2D was 65 mg daily. An overall response rate of 75% was observed in patients with CLL at 65 mg daily., Significance: This first-in-human phase I study demonstrates the safety and preliminary efficacy of nemtabrutinib in patients with relapsed/refractory B-cell malignancies. These data support further exploration of nemtabrutinib in larger clinical studies. This article is featured in Selected Articles from This Issue, p. 5., (©2023 American Association for Cancer Research.)

Chronic lymphocytic leukemia (CLL) is a disease characterized by the accumulation of mature CD19 + CD5 + CD23 + B cells in the bloodstream and in lymphoid organs. It usually affects people over 70 years of age, which limits the options for treatments. The disease is typically well-managed, but to date is still incurable. Hence, the need for novel therapeutic strategies remains. Nurse-like cells (NLCs) are major components of the microenvironment for CLL, supporting tumor cell survival, proliferation, and even drug resistance. They are of myeloid lineage, guided toward differentiating into their tumor-supportive role by the CLL cells themselves. As such, they are analogous to tumor-associated macrophages and represent a major therapeutic target. Previously, it was found that a mushroom extract, Active Hexose-Correlated Compound (AHCC), promoted the death of acute myeloid leukemia cells while preserving normal monocytes. Given these findings, it was asked whether AHCC might have a similar effect on the abnormally differentiated myeloid-lineage NLCs in CLL. CLL-patient PBMCs were treated with AHCC, and it was found that AHCC treatment showed a direct toxic effect against isolated CLL cells. In addition, it significantly reduced the number of tumor-supportive NLCs and altered their phenotype. The effects of AHCC were then tested in the Eµ-TCL1 mouse model of CLL and the Mll PTD/WT Flt3 ITD/WT model of AML. Results showed that AHCC not only reduced tumor load and increased survival in the CLL and AML models, but it also enhanced antitumor antibody treatment in the CLL model. These results suggest that AHCC has direct and indirect effects against CLL and that it may be of benefit when combined with existing treatments.

Competing Interests: RM, BC, SM, and AHS are AbbVie employees and may hold stock or options. SG, AAS, and SYK were employed at AbbVie when this work was conducted and may hold AbbVie stock or options. TL is a Genentech employee and may own stock. APK receives research funding from Janssen, AbbVie, Roche/Genentech, Astra Zeneca, and BMS and is a member of advisory boards for Janssen, AbbVie, Roche/Genentech, and BMS. APK also receives speaker fees from AbbVie. SS receives honoraria for consultancy, speaker honoraria, research grants, and travel support from AbbVie, Amgen, AstraZeneca, Celgene, Gilead, GSK, Hoffman La-Roche, Janssen, and Novartis and is an advisory board member for AbbVie, Amgen, AstraZeneca, Celgene, Gilead, Glaxo-Smith Kline, Hoffman La-Roche, Janssen, and Novartis. JFS receives research funding from AbbVie, Celgene, Janssen, and Roche, provides expert testimony for Celgene and Roche, is on the speakers’ bureau for AbbVie, Celgene, and Roche, and is an advisory board member for AbbVie, Astra Zeneca, Celgene, Genentech, Gilead, Janssen, Mei Pharma, Morphosys, Roche, Sunesis, and Takeda. AWR is an employee of the Walter and Eliza Hall Institute which has received venetoclax-related milestone and royalty payments in which he shares. AWR received research funding from Abbvie and holds a patent related to venetoclax. JAW is a consultant for AbbVie, Pharmacyclics, Janssen, Astra Zeneca, Beigene, and Arqule.

ELEVATE-RR demonstrated noninferior progression-free survival and lower incidence of key adverse events (AEs) with acalabrutinib vs ibrutinib in previously treated chronic lymphocytic leukemia. We further characterize AEs of acalabrutinib and ibrutinib via post hoc analysis. Overall and exposure-adjusted incidence rate was assessed for common Bruton tyrosine kinase inhibitor-associated AEs and for selected events of clinical interest (ECIs). AE burden scores based on previously published methodology were calculated for AEs overall and selected ECIs. Safety analyses included 529 patients (acalabrutinib, n = 266; ibrutinib, n = 263). Among common AEs, incidences of any-grade diarrhea, arthralgia, urinary tract infection, back pain, muscle spasms, and dyspepsia were higher with ibrutinib, with 1.5- to 4.1-fold higher exposure-adjusted incidence rates. Incidences of headache and cough were higher with acalabrutinib, with 1.6- and 1.2-fold higher exposure-adjusted incidence rate, respectively. Among ECIs, incidences of any-grade atrial fibrillation/flutter, hypertension, and bleeding were higher with ibrutinib, as were exposure-adjusted incidence rates (2.0-, 2.8-, and 1.6-fold, respectively); incidences of cardiac events overall (the Medical Dictionary for Regulatory Activities system organ class) and infections were similar between arms. Rate of discontinuation because of AEs was lower for acalabrutinib (hazard ratio, 0.62; 95% confidence interval, 0.41-0.93). AE burden score was higher for ibrutinib vs acalabrutinib overall and for the ECIs atrial fibrillation/flutter, hypertension, and bleeding. A limitation of this analysis is its open-label study design, which may influence the reporting of more subjective AEs. Overall, event-based analyses and AE burden scores demonstrated higher AE burden overall and specifically for atrial fibrillation, hypertension, and hemorrhage with ibrutinib vs acalabrutinib. This trial was registered at www.clinicaltrials.gov as #NCT02477696., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Purpose: Acquired mutations in Bruton's tyrosine kinase (BTK) or phospholipase C-γ2 (PLCG2) genes are associated with clinical progressive disease (PD) in patients with chronic lymphocytic leukemia (CLL) treated with BTK inhibitors. Data on mutation rates in patients without PD on ibrutinib treatment are limited., Experimental Design: We evaluated frequency and time to detection of BTK and PLCG2 mutations in peripheral blood samples from 388 patients with previously untreated (n = 238) or relapsed/refractory (n = 150) CLL across five clinical trials., Results: With median follow-up of 35 months (range, 0-72) without PD at last sampling, mutations in BTK (3%), PLCG2 (2%), or both genes (1%) were rare in previously untreated patients. With median follow-up of 35 months (range, 1-70) without PD at last sample, mutations in BTK (30%), PLCG2 (7%), or both genes (5%) were more common in patients with relapsed/refractory CLL. Median time to first detection of BTK C481S mutation was not reached in previously untreated patients and was >5 years in patients with relapsed/refractory CLL. Among patients evaluable at PD, previously untreated patients (n = 12) had lower rates than those with relapsed/refractory disease (n = 45) of BTK (25% vs. 49%) and PLCG2 mutations (8% vs. 13%). Time from first detection of BTK C481S mutation to PD was 11.3 months in 1 previously untreated patient and median 8.5 months (range, 0-35.7) among 23 patients with relapsed/refractory CLL., Conclusions: This systematic investigation describes development of mutations over time in patients without PD and informs the potential clinical opportunity to optimize ongoing benefits for such patients., (©2023 The Authors; Published by the American Association for Cancer Research.)

Background: Patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) have poor outcomes after the failure of covalent Bruton's tyrosine kinase (BTK) inhibitor treatment, and new therapeutic options are needed. Pirtobrutinib, a highly selective, noncovalent (reversible) BTK inhibitor, was designed to reestablish BTK inhibition., Methods: We conducted a phase 1-2 trial in which patients with relapsed or refractory B-cell cancers received pirtobrutinib. Here, we report efficacy results among patients with CLL or SLL who had previously received a BTK inhibitor as well as safety results among all the patients with CLL or SLL. The primary end point was an overall response (partial response or better) as assessed by independent review. Secondary end points included progression-free survival and safety., Results: A total of 317 patients with CLL or SLL received pirtobrutinib, including 247 who had previously received a BTK inhibitor. Among these 247 patients, the median number of previous lines of therapy was 3 (range, 1 to 11), and 100 patients (40.5%) had also received a B-cell lymphoma 2 (BCL2) inhibitor such as venetoclax. The percentage of patients with an overall response to pirtobrutinib was 73.3% (95% confidence interval [CI], 67.3 to 78.7), and the percentage was 82.2% (95% CI, 76.8 to 86.7) when partial response with lymphocytosis was included. The median progression-free survival was 19.6 months (95% CI, 16.9 to 22.1). Among all 317 patients with CLL or SLL who received pirtobrutinib, the most common adverse events were infections (in 71.0%), bleeding (in 42.6%), and neutropenia (in 32.5%). At a median duration of treatment of 16.5 months (range, 0.2 to 39.9), some adverse events that are typically associated with BTK inhibitors occurred relatively infrequently, including hypertension (in 14.2% of patients), atrial fibrillation or flutter (in 3.8%), and major hemorrhage (in 2.2%). Only 9 of 317 patients (2.8%) discontinued pirtobrutinib owing to a treatment-related adverse event., Conclusions: In this trial, pirtobrutinib showed efficacy in patients with heavily pretreated CLL or SLL who had received a covalent BTK inhibitor. The most common adverse events were infections, bleeding, and neutropenia. (Funded by Loxo Oncology; BRUIN ClinicalTrials.gov number, NCT03740529.)., (Copyright © 2023 Massachusetts Medical Society.)

Introduction: Chronic lymphocytic leukemia (CLL) commonly affects older adults. However, few studies have examined the relationship between baseline geriatric domains and clinical outcomes in this population. Here, we aim to evaluate the use of a comprehensive geriatric assessment in older (>65 years) untreated patients with CLL to predict outcomes., Materials and Methods: We conducted a planned analysis of 369 patients with CLL age 65 or older treated in a phase 3 randomized trial of bendamustine plus rituximab versus ibrutinib plus rituximab versus ibrutinib alone (A041202). Patients underwent evaluations of geriatric domains including functional status, psychological status, social activity, cognition, social support, and nutritional status. We examined associations among baseline geriatric domains with grade 3+ adverse events using multivariable logistic regression and overall survival (OS) and progression-free survival (PFS) using multivariable Cox regression models., Results: In this study, the median age was 71 years (range: 65-87). In the combined multivariable model, the following geriatric domains were significantly associated with PFS: Medical Outcomes Study (MOS) - social activities survey score (hazard ratio [HR] [95% confidence interval (CI)] 0.974(0.961, 0.988), p = 0.0002) and nutritional status (≥5% weight loss in the preceding six months: (HR [95% CI] 2.717[1.696, 4.354], p < 0.001). MOS - social activities score [HR (95% CI) 0.978(0.958, 0.999), p = 0.038] was associated with OS. No geriatric domains were significantly associated with toxicity. There were no statistically significant interactions between geriatric domains and treatment., Discussion: Geriatric domains of social activity and nutritional status were associated with OS and/or PFS in older adults with CLL. These findings highlight the importance of assessing geriatric domains to identify high-risk patients with CLL who may benefit from additional support during treatment., Competing Interests: Declaration of Competing Interest PCJ has consulted for AstraZeneca, ADC Therapeutics, and Seagen. JAW has consulted for Abbvie, AstraZeneca, Beigene, Genentech, Janssen, Pharmacyclics, Loxo/Lilly, Merck, and Newave. RAN received equity stock payment from TimeDoc. CO has consulted for Janssen, Beigene, AbbVie, Astrazeneca, Merck and Roche. WD has consulted for Merck, BeiGene, MEI pharama, Alexion and Octapharma. DMS has consulted for Pharmacyclics/Janssen, Karyopharm Therapeutics, Beigene, Innate, AstraZeneca, Abbvie, CSL Behring, Celegene, TG Therapeutics, and Innate Pharma. ASR served on a DSMC for Telios and is an employee of Eli Lilly, although employment began after this work was completed. RS has consulted for GlaxoSmithKline, Hermavant, Takeda, Abbvie, Amgen, AvenCell, BerGenBio, Cellularity, CTI pharma, Jazz, Kura Onc, Rigel, Syros, Novartis, Actinium, Arog, BMS, Boston Pharmaceuticals, and Janssen., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Importance: Ibrutinib has been associated with serious cardiotoxic arrhythmias. In preclinical models, these events are paralleled or proceeded by diffuse myocardial injury (inflammation and fibrosis). Yet whether this is seen in patients or has implications for future cardiotoxic risk is unknown., Objective: To assess the incidence and outcomes of myocardial injury among patients with ibrutinib-related cardiotoxicity., Design, Setting, and Participants: This cohort study included consecutive patients treated with ibrutinib from 2012 to 2019, phenotyped using cardiovascular magnetic resonance (CMR) from a large US Comprehensive Cancer Center registry., Exposures: Ibrutinib treatment for cancer control., Main Outcomes and Measures: The primary outcome was the presence of late gadolinium enhancement (LGE) fibrosis. The secondary outcome was the occurrence of major adverse cardiac events (MACE), defined as atrial fibrillation, heart failure, symptomatic ventricular arrhythmias, and sudden death of probable or definite ibrutinib association after CMR. We also assessed parametric-mapping subclinical fibrosis (native-T1, extracellular volume fraction) and inflammation/edema (max-T2) measures. Cardiovascular magnetic resonance measures were compared with those obtained in similar consecutive patients with cancer without ibrutinib treatment (pretreatment controls). Observed measures were also compared with similar-aged broad population rates (general-population controls) and a broader pool of cardiovascular disease (CVD) risk-matched cancer controls. Multivariable regression was used to assess the association between CMR measures and MACE., Results: Overall, 49 patients treated with ibrutinib were identified, including 33 imaged after treatment initiation (mean [SD] age, 65 [10] years, 9 [27%] with hypertension, and 23 [69.7%] with index-arrhythmias); median duration of ibrutinib-use was 14 months. The mean (SD) pretreatment native T1 was 977.0 (73.0) ms, max-T2 56.5 (4.0) ms, and 4 (13.3%) had LGE. Posttreatment initiation, mean (SD) native T1 was 1033.7 (48.2) ms, max-T2 61.5 (4.8) ms, and 17 (54.8%) had LGE (P < .001, P = .01, and P < .001, respectively, pre- vs post-ibrutinib treatment). Native T12SDs was elevated in 9 (28.6%), and max-T22SDs in 21 (63.0%), respectively. Cardiovascular magnetic resonance measures were highest in those with suspected toxic effects (P = .01 and P = .01, respectively). There was no association between traditional CVD-risk or cancer-treatment status and abnormal CMR measures. Among those without traditional CVD, 16 (58.6%) had LGE vs 38 (13.3%) in matched-controls (relative-risk, 4.8; P < .001). Over a median follow-up of 19 months, 13 (39.4%) experienced MACE. In multivariable models inclusive of traditional CVD risk factors, LGE (hazard ratio [HR], 4.9; P = .04), and native-T12SDs (HR, 3.3; P = .05) associated with higher risks of MACE., Conclusions and Relevance: In this cohort study, myocardial injury was common in ibrutinib users, and its presence was associated with higher cardiotoxic risk.

We assessed vaccine-induced antibody responses to the SARS-CoV-2 ancestral virus and Omicron variant before and after booster immunization in 57 patients with B cell malignancies. Over one-third of vaccinated patients at the pre-booster time point were seronegative, and these patients were predominantly on active cancer therapies such as anti-CD20 monoclonal antibody. While booster immunization was able to induce detectable antibodies in a small fraction of seronegative patients, the overall booster benefit was disproportionately evident in patients already seropositive and not receiving active therapy. While ancestral virus- and Omicron variant-reactive antibody levels among individual patients were largely concordant, neutralizing antibodies against Omicron tended to be reduced. Interestingly, in all patients, including those unable to generate detectable antibodies against SARS-CoV-2 spike, we observed comparable levels of EBV- and influenza-reactive antibodies, demonstrating that B cell-targeting therapies primarily impair de novo but not preexisting antibody levels. These findings support rationale for vaccination before cancer treatment.

Primary results from the phase 3 RESONATE-2 study demonstrated superior efficacy and tolerability with ibrutinib versus chlorambucil in patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). Here, we describe characteristics and outcomes of patients who received ibrutinib treatment for ≥5 years in RESONATE-2. Patients aged ≥65 years with previously untreated CLL/SLL, without del(17p), were randomly assigned 1:1 to once-daily ibrutinib 420 mg until disease progression/unacceptable toxicity (n = 136) or chlorambucil 0.5−0.8 mg/kg for ≤12 cycles (n = 133). Baseline characteristics in ibrutinib-randomized patients (n = 136) were generally similar between patients on ibrutinib treatment for ≥5 years (n = 79) versus those on treatment for <5 years (n = 57). In patients on ibrutinib treatment for ≥5 years, complete response rates improved over time, reaching 42% by 5 years. Estimated 7-year progression-free survival and overall survival rates were 82% and 94%, respectively. Adverse events (AEs) led to dose reductions in 16/79 patients (20%); these AEs were resolved for 13/16 patients (81%). AEs led to dose holds (≥7 days) in 45/79 patients (57%); these AEs were resolved for 43/45 patients (96%). More than half (58%) of ibrutinib-randomized patients benefitted from ibrutinib treatment for ≥5 years regardless of baseline characteristics. Dose modification resolved AEs for most patients, thereby facilitating continued treatment.

Chronic lymphocytic leukemia (CLL) transformation to aggressive lymphoma, known as Richter's Transformation (RT), has a dismal prognosis. There are limited data evaluating risk of RT in patients treated with ibrutinib. We performed a retrospective analysis to determine prognostic variables associated with development of RT and overall survival (OS) at progression after treatment with ibrutinib. We identified 559 patients with CLL treated with ibrutinib from 2010-2019. After a median follow-up of 44.5 months from ibrutinib start, 179 patients progressed and were included in our analysis. After a median follow-up of 20.8 months from progression, 54 out of 179 patients developed RT. Progression on treatment (hazard ratio [HR] 4.01 [1.60-10.00], p = .003), higher LDH (HR 1.80 for 2-fold increase [1.33-2.43], p = .0001), and lymphadenopathy without lymphocytosis (HR 2.88 [1.15-7.20], p = .02) were independent prognostic variables for the development of RT at progression. Progression with lymphadenopathy without lymphocytosis continued to be an independent prognostic variable of worse OS post-progression. In a subset analysis of 50 patients who obtained a PET-CT at progression, the median SUV max for patients who would develop RT was 15.2 (n = 30, range: 4.0-46.3) versus those patients who did not develop RT with a SUV max of 7.7 (n = 20, range: 2.3-27.2) (p = .0030). Median OS from date of RT was 4.0 months, suggesting that prognosis for RT remains poor. A lymph node biopsy to rule out RT should be considered in patients who received ibrutinib who progress on treatment, have an elevated LDH, or progress with lymphadenopathy without lymphocytosis., (© 2022 Wiley Periodicals LLC.)

The therapeutic landscape for chronic lymphocytic leukemia (CLL) has changed dramatically over the past decade as our understanding of the biology of CLL has advanced, allowing the development of oral therapies targeting key drivers of CLL. Currently, inhibitors of Bruton's Tyrosine Kinase and the BH3 mimetic venetoclax are standards of care for both frontline and relapsed/refractory CLL. Sequencing of available therapies, therefore, has become a major challenge of therapy. In this review, we will focus on the current landscape for the treatment of relapsed/refractory CLL. We will also discuss important considerations when sequencing these available treatments. The recent advances in this disease are significant steps forward, and raise new questions of how these available drugs should be given as well as how we can continue to improve the treatment of CLL., (© 2022 The Author. American Journal of Hematology published by Wiley Periodicals LLC.)

Successes with anti-CD20 antibodies in chronic lymphocytic leukemia (CLL) and enhanced activity of Fc-engineered vs unmodified antibody therapy suggest a potentially impactful role for natural killer (NK) cells and other innate immune cells in controlling this disease. Stimulated NK cells have shown promise as a cellular therapy, but their application has been constrained by limited expansion capacity and low cytotoxic activity against CLL cells. Here, we demonstrate that both healthy donor-derived and CLL patient-derived NK cells expand rapidly when stimulated with feeder cells expressing membrane-bound interleukin-21 (mbIL-21) and have potent cytotoxic activity against allogeneic or autologous CLL cells. Combination with anti-CD20 antibodies significantly enhances NK recognition and killing of CLL targets. As any CLL immune therapy would likely be given in combination, we assess commonly used treatments and demonstrate that ibrutinib has mixed suppressive and protective effects on expanded NK cells, whereas expanded NKs are highly resistant to venetoclax. We demonstrate efficacy in vivo in 2 xenograft mouse models of human CLL that support building upon a regimen of venetoclax and obinutuzumab with mbIL-21-expanded NK cells. Collectively, these data support development of mbIL-21-expanded NKs combined with the CD20 antibody obinutuzumab and venetoclax in the treatment of CLL., (© 2022 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Cytotoxic T lymphocyte antigen 4 (CTLA4) is a major immune checkpoint and target for cancer immunotherapy. Although originally discovered and primarily studied on T cells, its role on other cell types has also been recognized in recent years. Here we describe an unexpected interaction between ibrutinib (a targeted inhibitor of Bruton tyrosine kinase [BTK]) and CTLA4 expression on malignant chronic lymphocytic leukemia (CLL) cells. Although BTK itself does play a role in CTLA4 expression in CLL, we demonstrate that ibrutinib's main suppressive effect on CTLA4 protein expression and trafficking occurs through non-BTK targets influenced by this drug. This suppression is not seen in T cells, indicating a different mechanism of CTLA4 regulation in CLL vs T cells. Appreciating this distinct mechanism and the beneficial non-BTK effects of ibrutinib may contribute to understanding the immune benefits of ibrutinib treatment and lead to therapeutic approaches to improve immune function in patients with CLL by suppressing CTLA4 expression., (© 2022 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia, but, despite advances in treatment, many patients still experience relapse. CLL cells depend on interactions with supportive cells, and nurse-like cells (NLCs) are the major such cell type. However, little is known about how NLCs develop. Here, we performed DNA methylation analysis of CLL patient-derived NLCs using the 850K Illumina array, comparing CD14 + cells at day 1 (monocytes) versus day 14 (NLCs). We found a strong loss of methylation in AP-1 transcription factor binding sites, which may be driven by MAPK signaling. Testing of individual MAPK pathways (MEK, p38, and JNK) revealed a strong dependence on MEK/ERK for NLC development, because treatment of patient samples with the MEK inhibitor trametinib dramatically reduced NLC development in vitro. Using the adoptive transfer Eµ-TCL1 mouse model of CLL, we found that MEK inhibition slowed CLL progression, leading to lower WBC counts and to significantly longer survival time. There were also lower numbers of mouse macrophages, particularly within the M2-like population. In summary, NLC development depends on MEK signaling, and inhibition of MEK leads to increased survival time in vivo. Hence, targeting the MEK/ERK pathway may be an effective treatment strategy for CLL., (Copyright © 2022 by The American Association of Immunologists, Inc.)

Purpose: Dual blockade of Bruton's tyrosine kinase with ibrutinib and selinexor has potential to deepen responses for patients with chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL)., Patients and Methods: In this phase I study (clinicaltrials.gov: NCT02303392), adult patients with CLL/NHL, relapsed/refractory to ≥1 prior therapy were enrolled. Patients received weekly oral selinexor and daily oral ibrutinib in 28-day cycles until progression or intolerance. Primary objective was to determine MTD., Results: Included patients had CLL (n = 16) or NHL (n = 18; 9 Richter transformation, 6 diffuse large B-cell lymphoma, and 3 mantle cell lymphoma). Median prior therapies were 4 (range = 1-14) and 59% previously received ibrutinib. The established MTD was 40 mg of selinexor (days 1, 8, 15) and 420 mg daily ibrutinib. Common nonhematologic adverse events were fatigue (56%), nausea (53%), anorexia (41%), and diarrhea (41%) and were mostly low grade. Overall response rate was 32%. An additional 47% achieved stable disease (SD), some prolonged (up to 36 months). Median progression-free survival for patients with CLL and NHL was 8.9 [95% confidence interval (CI), 3.9-16.1] and 2.7 (95% CI, 0.7-5.4) months, respectively. For patients with CLL who did not receive prior ibrutinib, only 20% (1/5) progressed. Estimated 2-year overall survival was 73.7% (95% CI, 44.1-89.2) and 27.8% (95% CI, 10.1-48.9) for patients with CLL and NHL, respectively., Conclusions: The selinexor and ibrutinib combination has demonstrated tolerability in patients with relapsed/refractory CLL/NHL. Responses were durable. Notable responses were seen in patients with CLL with minimal prior therapy. Future study of this combination will focus on efforts to deepen remissions in patients with CLL receiving ibrutinib therapy., (©2022 American Association for Cancer Research.)

The existence of "leukemia-initiating cells" (LICs) in chronic lymphocytic leukemia (CLL) remains controversial due to the difficulty in isolating and identifying the tumor-initiating cells. Here, we demonstrate a microchannel electroporation (MEP) microarray that injects RNA-detecting probes into single live cells, allowing the imaging and characterization of heterogeneous LICs by intracellular RNA expression. Using limited-cell FACS sequencing (LC-FACSeq), we can detect and monitor rare live LICs during leukemogenesis and characterize their differential drug sensitivity. Disease-associated mutation accumulation in developing B lymphoid but not myeloid lineage in CLL patient hematopoietic stem cells (CLL-HSCs), and development of independent clonal CLL-like cells in murine patient-derived xenograft models, suggests the existence of CLL LICs. Furthermore, we identify differential protein ubiquitination and unfolding response signatures in GATA2 high CLL-HSCs that exhibit increased sensitivity to lenalidomide and resistance to fludarabine compared to GATA2 low CLL-HSCs. These results highlight the existence of therapeutically targetable disease precursors in CLL., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2022. Published by Elsevier Inc.)