Bruton's Tyrosine Kinase Inhibitor Research Articles

BELLWAVE-010: A phase 3 study of nemtabrutinib plus venetoclax versus venetoclax plus rituximab (VR) in previously treated patients (pts) with relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL).

TPS7089 Background: VR is a standard of care option for pts with CLL/SLL who have relapsed after ≥1 line of prior therapy. However, there is an unmet need for more effective treatments. Bruton tyrosine kinase (BTK) plays an important role in the pathogenesis of CLL. Nemtabrutinib is a BTK inhibitor that targets both wild type and C481-mutant forms of BTK. In the ongoing BELLWAVE-001 study, nemtabrutinib demonstrated manageable safety and durable antitumor activity in pts with R/R CLL/SLL with and without C481 mutations. The randomized, open-label, phase 3 BELLWAVE-010 study (NCT05947851) is designed to evaluate the efficacy and safety of nemtabrutinib + venetoclax versus VR as second-line or later treatment for pts with R/R CLL/SLL. Methods: Eligible pts are aged ≥18 years with active R/R CLL/SLL after ≥1 prior therapy per iwCLL 2018 criteria and an ECOG PS of 0-2. Approximately 720 pts will be enrolled in 2 parts. Part 1 is an open-label, nonrandomized dose escalation and confirmation phase to evaluate safety and determine the optimal dose of nemtabrutinib + venetoclax. Part 1 will enroll 30 pts to establish the dose of nemtabrutinib using a modified toxicity probability interval design. Pts will receive nemtabrutinib at 2 dose levels (45 mg PO QD starting dose, escalating to 65 mg PO QD) for 28 days, followed by nemtabrutinib + venetoclax (20-400 mg PO QD ramp up over 4 weeks). Part 2 is an open-label, parallel-group, randomized phase comparing the efficacy and safety of nemtabrutinib + venetoclax with VR. In part 2, approximately 690 pts will be randomly assigned 1:1 to receive either nemtabrutinib at the recommended dose for 28 days followed by the nemtabrutinib + venetoclax or venetoclax + rituximab (or rituximab biosimilar; 375 mg/m2 at week 6, followed by 500 mg/m2 every 4 weeks starting at week 10 until week 26 [total 6 doses]). Study treatment will continue for approximately 2 years or until unacceptable toxicity, disease progression, or other discontinuation criteria are met. Randomization will be stratified by BTK-C481 mutation status (detected vs not detected), geographic region (US/Canada vs Europe vs rest of world) and risk (high risk [del(17p) and/or TP53-mutated and/or IGHV-unmutated] vs low risk [absence of high-risk factors]). The primary end point for part 2 is progression-free survival by blinded independent central review (BICR) per iwCLL 2018 criteria. Secondary end points for part 2 are undetectable minimal residual disease in bone marrow at month 14 by central laboratory assessment, objective response rate (ORR), and duration of response by BICR per iwCLL 2018 criteria, overall survival, and safety. Exploratory end points are ORR including partial response with lymphocytosis, pharmacokinetics, and health-related quality of life. Recruitment is ongoing. Clinical trial information: NCT05947851 .

A retrospective observational study of rapid titration of venetoclax (VEN) in patients with mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL).

e19018 Background: CLL and MCL can present with rapid disease progression that requires quick control. VEN is an oral, small-molecule inhibitor of BCL-2 that requires careful dose titration to avoid TLS. However, standard outpatient titration of VEN takes 29 days to reach max dose, with the low doses achieving little disease control. A common practice at our site is to rapidly titrate VEN to 100mg within 1 week with hospitalization for careful TLS monitoring and management. We present the safety and outcomes of 39 identified patients treated as such. Methods: The rapid VEN titration plan was: VEN 20mg x 2 days, 50mg x 2 days, then 100mg daily with q6-q8 hour monitoring of TLS labs plus ongoing IV hydration and allopurinol with or without rasburicase per clinical judgment. Most patients were treated in such manner if TLS did not occur. Clinically stable patients were typically discharged after 2 days of VEN 100mg, then continued weekly outpatient dose escalation to the 200mg and then the 400mg dose levels. If a patient was progressing on a Bruton's Tyrosine Kinase inhibitor, the inhibitor was often given concurrently with the early doses of VEN. Results: Patient characteristics are listed in the table. 23% (5 of 22) of patients with CLL and 35% (6 of 17) of patients with MCL had laboratory TLS (Howard SC, NEJM2011). In the patients with CLL, 2/5 were low risk for TLS, and in the patients with MCL, 3/6 were low risk for TLS. Only 4.5% (1 of 22) of CLL patients and no MCL patients had clinical TLS (Grade 2 creatinine elevation). In that specific patient, considered low risk for TLS, the elevated creatinine did not recover but was subsequently deemed secondary to Richter’s transformation involving the kidneys. No unexpected toxicity was observed outside of those typically associated with VEN and anti-CD20 antibody, when used. The mean number of days to reach 100mg was 6.5 days (quartile [Q] 1:5d; Q3: 10d), and the mean number of days to reach the planned VEN target dose was 18.8 with range (Q1:14d; Q3: 25d). Sixty-four percent of patients achieved the 400mg dose level. Conclusions: This single-institution retrospective analysis highlights the low rate of clinical TLS when using VEN with rapid titration in a controlled environment for high-risk patients needing rapid disease control. However, lab TLS occurred in low-risk patients treated in this manner, necessitating hospitalization despite low risk. No unexpected or additional toxicity was observed. [Table: see text]

Glofitamab monotherapy in patients with heavily pretreated relapsed/refractory (R/R) mantle cell lymphoma (MCL): Updated analysis from a phase I/II study.

7008 Background: Glofitamab, a bispecific antibody with a novel 2:1 (CD20:CD3) format, engages and redirects T cells to eliminate malignant B cells. In a Phase I/II study (NCT03075696), fixed-duration glofitamab monotherapy showed high, durable complete responses (CR) and manageable safety in patients (pts) with heavily pretreated R/R MCL (Phillips et al. ASH 2022). We report updated efficacy and safety data for pts with R/R MCL. Methods: Pts received obinutuzumab pretreatment (Gpt; 1000mg or 2000mg) 7 days before their first glofitamab dose. Glofitamab step-up dosing was given on Cycle (C) 1 Day (D) 8 (2.5mg) and D15 (10mg), and target dose (16mg or 30mg) from C2D1 to C12 as a fixed-duration therapy. Efficacy endpoints were CR, overall response rate (ORR), duration of CR (DOCR), duration of response (DOR) and progression-free survival (PFS). Post-hoc PFS and overall survival (OS) landmark analyses were performed in pts with a CR at end of treatment (EOT). Results: As of Sept 4, 2023, 61 pts were enrolled; 60 received study treatment (1000mg Gpt, n=16; 2000mg Gpt, n=44). Median number of prior lines of therapy was 2 (range: 1–5); 73.3% were refractory to the last line of prior therapy. Median duration of glofitamab therapy was 7.4 months; median number of cycles was 12. Of the 31 pts (51.7%) who received prior Bruton’s tyrosine kinase inhibitor (BTKi) therapy, 29 (93.5%) were BTKi refractory; median number of prior lines of therapy was 3 (range: 1–5); 90.0% were refractory to the last line of prior therapy. At a median PFS follow-up of 17.2 months, ORR and CR rate were 85.0% and 78.3%, respectively. Median DOCR was 15.4 months; the majority of CRs (28/47; 59.6%) were ongoing at data cut-off. Of 19 pts with a CR, 9 had disease progression and 10 died (fatal adverse event [AE], n=8; COVID, n=7; septic shock, n=1). Estimated 12-month DOCR and DOR rates were 71.0% and 66.6%, respectively. Median PFS was 16.8 months. Landmark analyses indicated that most pts with a CR at EOT were alive and progression free 15 months post-EOT (OS rate, 72.7%; PFS rate, 59.2%). Observed efficacy data were consistent across both Gpt cohorts. In post-BTKi pts after a median PFS follow-up of 26.1 months, ORR and CR rate were 74.2% and 71.0%, respectively. Median DOCR was 12.6 months; median PFS was 8.6 months. No new safety signals were observed. Cytokine release syndrome (CRS) remained the most common AE (42/60, 70.0%; Grade 1/2, 58.3%) and was lower in the 2000mg (63.6%) vs the 1000mg (87.5%) Gpt cohort. Glofitamab monotherapy (2000mg Gpt) is currently under investigation in the Phase III GLOBRYTE study (NCT06084936). Conclusions: Fixed-duration glofitamab continues to demonstrate compelling response rates that are maintained beyond EOT, with long-term durability observed in heavily pretreated pts with R/R MCL, including pts with prior BTKi therapy. The safety profile was manageable and CRS mainly low grade. Clinical trial information: NCT03075696 .

Comparative efficacy of Bruton tyrosine kinase inhibitors in the treatment of relapsed/refractory chronic lymphocytic leukemia: A network meta-analysis (NMA).

7048 Background: Next-generation Bruton’s tyrosine kinase inhibitors (BTKis) have led to changes in the treatment algorithm for patients with high-risk relapsed/refractory (R/R) CLL; defined based on the presence of genetic mutations and a high unmet need. Given the lack of head-to-head trials comparing these treatments in R/R CLL, a NMA was performed to estimate the relative efficacy of BTKis used to treat high-risk patients. Methods: Randomized controlled trials ALPINE (zanubrutinib vs. ibrutinib), ELEVATE-RR (acalabrutinib vs. ibrutinib), and ASCEND (acalabrutinib vs. bendamustine + rituximab/idelalisib + rituximab [BR/IR]) were included in the NMA. High-risk populations were defined based on the pre-specified subgroups within each trial, including patients with del17p and/or TP53 mutations in ALPINE (zanubrutinib: 75/327 and ibrutinib: 75/325), ASCEND (acalabrutinib: 44/155 and BR/IR: 42/155), and del17p/del11q in ELEVATE-RR (acalabrutinib: 268/268 and ibrutinib: 265/265). Bayesian NMAs were used to estimate hazard ratios (HRs) or odds ratios (ORs) with 95% credible intervals (CrIs), and probability better (PB) for zanubrutinib versus all other treatments. Outcomes analysed included investigator-assessed progression-free survival (PFS), overall survival (OS), overall response (ORR), and complete response (CR). Given the timing of the included trials in relation to the COVID-19 pandemic, ALPINE data were analyzed with and without adjustment for COVID-19 related deaths. Results: The NMA found a statistically significant improvement in PFS for zanubrutinib over acalabrutinib in high-risk patients and a trend towards improvement in OS, ORR, and CR (Table). Zanubrutinib led to statistically significant improvements in PFS versus ibrutinib (HR [95% CrI]: 0.49 [0.30, 0.78], PB: 99.9%) and BR/IR (0.12 [0.05, 0.26], PB: 100.0%). For OS, zanubrutinib showed a trend towards improvement versus ibrutinib (0.59 [0.31, 1.12] PB: 94.8%) and BR/IR (0.64 [0.24, 1.74] PB: 80.7%). Conclusions: This NMA found zanubrutinib to be the most efficacious BTKi for patients with high-risk R/R CLL, offering significantly delayed disease progression, and favourable survival and response vs. alternative BTKi treatments. [Table: see text]

Comparison of zanubrutinib (zanu) and acalabrutinib (acala) in B-cell malignancies: An adverse event (AE)-based analysis.

e19049 Background: Acala and zanu are 2nd generation Bruton tyrosine kinase inhibitors (BTKis) that have demonstrated improved safety profiles vs 1st generation BTKi ibrutinib in clinical trials. While head-to-head comparison of zanu vs acala is lacking, a recent meta-analysis of clinical trials provided a comprehensive, indirect comparison of the AE profiles in B-cell malignancies (Hwang, Hemasphere. 2023;7(S3):1134). This study aims to evaluate costs and impacts on quality of life (QoL) for zanu vs acala using their AE profiles. Methods: A health economic model was developed to determine cost and QoL associated with AE management for zanu and acala. The incidence rates ( IRs) of all grade and grade ≥3 AEs of interest (n=21, including bleeding events, hypertension, atrial fibrillation, cytopenias, infections, headache, arthralgia, diarrhea) were taken from the meta-analysis. Additional model inputs, such as disutility, average duration of AE, and unit cost of each AE were sourced from published literature and publicly available cost databases in consultation with clinical experts. The model was developed from the US perspective, considering Medicare costs, inflated to 2023 USD. Model outcomes were AE management cost (= IR * unit cost) and quality-adjusted life years (QALYs) lost due to AE (= IR * Disutility * Duration/365.25). Results: In the base-case scenario (considering all AEs), treating a hypothetical cohort of 1000 patients (pts) with zanu instead of acala yielded cost savings of $124K and 3.7 QALY gains (i.e., 3.7 years extra in full health). Subgroup analysis for severe (grade ≥3) and non-severe AEs (grade 1-2) demonstrated similar trends. A sensitivity analysis limited to AEs significantly different between zanu and acala (n=13) yielded consistent results. Additionally, a probabilistic sensitivity analysis, conducted with 1000 iterations to account for uncertainty in model parameters, confirmed robustness of the model, indicating stable conclusions across a wide range of parameter uncertainties. Conclusions: This analysis suggested that zanu is cost-saving and associated with added health benefits compared to acala in terms of AE management in pts with B-cell malignancies. Should these results derived from meta-analysis of clinical trial data be applicable to real-world pt populations across different indications, the potential cost savings could be considerable. These results could be further improved if the differences in efficacy of zanu vs acala are also incorporated. [Table: see text]

Real-world Bruton tyrosine kinase inhibitor (BTKi) treatment patterns and outcomes among patients with chronic lymphocytic leukemia or small lymphocytic lymphoma (CLL/SLL) in US community oncology practices.

e19020 Background: BTKi therapies are standard of care for CLL/SLL, with acalabrutinib (acala) and zanubrutinib (zanu) having improved safety profiles vs ibrutinib (ibru). This study assessed real-world clinical characteristics, treatment patterns, and adverse events (AEs) among BTKi-treated patients with CLL/SLL. Methods: This is a retrospective observational study, updated with 5 months of additional data from a previous analysis. Adults in the US community oncology setting initiated BTKi treatment between Jan 1, 2020, and Jul 31, 2023, and were followed to Oct 31, 2023. De-identified structured electronic health records were analyzed from the Integra Connect-PrecisionQ real-world database. Cardiovascular (CV) AEs (based on ICD codes), time to treatment discontinuation (TTD), and time to next treatment (TTNT) were reported. Results: A total of 3064 patients initiated BTKi therapies during the index period (1L n=2815; 2L+ n=249). Median age (range) was 72 years (33-90) in 1L and 72 years (42-89) in 2L+. There were 63.1% and 65.5% males in 1L and 2L+, respectively. In 1L, 49.3% of patients were treated with ibru, 43.4% with acala, and 7.2% with zanu. Similar trends were observed for 2L+. More patients experienced CV AEs among those who received 1L ibru vs acala or zanu; 12.1%, 7.6%, and 7.3% at month 6 ( P<0.05) and 14.6%, 9.4%, and 8.5% at month 9 ( P<0.05). With longer follow-up, there was a trend for a more favorable CV safety profile for zanu. Of patients treated with 1L ibru, 12.7% discontinued ibru and switched to acala or zanu. Median TTD in 1L was shorter for ibru than acala or zanu (Table). The associated probability of remaining on treatment was higher with zanu vs ibru or acala at months 6 and 12 (Table). Median TTNT was not reached for zanu, while it was 30.2 months for ibru and 35.8 months for acala. Conclusions: While zanu had relatively smaller sample size and shorter follow-up, this study demonstrated better real-world safety and efficacy outcomes for acala and zanu vs ibru. Additional research is needed to explain and validate observed differences favoring zanu over acala. [Table: see text]

CELESTIAL-TNCLL: An ongoing, open-label, multiregional, phase 3 study of sonrotoclax (BGB-11417) + zanubrutinib vs venetoclax + obinutuzumab for treatment-naïve (TN) CLL.

TPS7087 Background: The combination of venetoclax (ven), the first-generation BCL2 inhibitor, and ibrutinib, a BTK inhibitor, has demonstrated efficacy in patients with CLL (Wierda et al. J Clin Oncol. 2021); however, the toxicity profile of this regimen suggests a need for a more tolerable BTK/BCL2 inhibitor combination. Sonrotoclax, a next generation BCL2 inhibitor, is a more selective and more pharmacologically potent inhibitor of BCL2 than venetoclax. In a phase 1 study in patients with TN CLL treated with sonrotoclax + zanubrutinib, efficacy data was promising with ORR and 1-year progression-free survival (PFS) rates of 100% and deep responses based on undetectable measurable residual disease at <10-4 sensitivity (uMRD4). The most common grade ≥3 TEAE was neutropenia, and no tumor lysis syndrome or cardiac toxicity was observed (Tam et al. Blood. 2023). Zanubrutinib, a next-generation BTK inhibitor, significantly improved PFS and had a more tolerable safety profile, including fewer cardiac adverse events vs ibrutinib in a randomized, head-to-head study of patients with CLL/SLL (Brown et al. N Engl J Med. 2023). Presented here is the design of a phase 3 trial aimed at comparing the efficacy of sonrotoclax + zanubrutinib vs ven + obinutuzumab (obi) in patients with TN CLL. Methods: CELESTIAL-TNCLL (BGB-11417-301; NCT06073821) is a randomized, open-label, phase 3 study. Eligible patients must have previously untreated CLL that requires treatment per 2018 iwCLL criteria, measurable disease by CT/MRI, an ECOG performance score of 0-2, and adequate hematologic and organ function. Approximately 640 patients will be randomized 1:1 to receive either 3 cycles of zanubrutinib monotherapy (320 mg total daily dose, orally), followed by zanubrutinib + sonrotoclax for 12 cycles, or standard ven + obi treatment for 12 cycles. Randomization will be stratified by age (<65 vs ≥65 years) and IGHV and del(17p)/ TP53 mutation status. The primary endpoint is PFS as assessed by independent review committee (IRC) according to 2018 iwCLL guidelines with modifications for treatment-related lymphocytosis for patients with CLL (Cheson et al. 2012). Key secondary endpoints include complete response rate (CRR), defined as CR or CR with incomplete hematopoietic recovery, assessed by IRC; rates of uMRD4 in bone marrow and peripheral blood at the first post-treatment follow-up visit based on next-generation sequencing by clonoSEQ; and overall survival. Other secondary endpoints include PFS as assessed by investigator (INV); CRR by INV; rate of uMRD4 based on flow cytometry; overall response rate by IRC and INV; duration of response by IRC and INV; patient-reported outcomes; and safety and tolerability. Recruitment is ongoing. Clinical trial information: NCT06073821 .

Glofitamab combined with poseltinib and lenalidomide for relapsed/refractory diffuse large B cell lymphoma: Interim analysis of GPL study.

7066 Background: Despite advanced treatments, including chimeric antigen receptor therapy (CAR-T), a significant proportion of patients succumb to relapsed and refractory diffuse large B cell lymphoma (R/R DLBCL). In vitro experiments suggest synergism between BTK inhibitor (BTKi) and T-cell engager, we initiated a multicenter trial of poseltinib and glofitamab in combination with lenalidomide in R/R DLBCL. Methods: This is a phase II, open label, single arm study aiming to enroll 76 participants with adult R/R DLBCL patients (NCT05335018). Patients refractory to frontline therapy or those who failed more than two lines of therapies were enrolled. Previous anti-CD19 CAR-T was allowed, while previous CD20 T-cell engager was not permitted. Participants received glofitamab (In cycle 1, dose is increased weekly from 2.5mg to 10mg, and after cycle 2, 30mg is administered on Day 1), lenalidomide (20mg daily from Day 1-14), and poseltinib (40mg twice daily from Day 1-21) (GPL) every 3 weeks for a total of 12 cycles(induction). Maintenance with poseltinib and lenalidomide for 17 cycles were given to patients after induction period. The primary endpoint is overall response rate (ORR), with secondary endpoints including duration of response (DoR), complete response rate (CRR), progression free survival (PFS), overall survival (OS), and incidence of treatment related adverse events. Results: No safety signals were observed in the safety cohort (n=6, 3+3 design). As of November 2023, 37 patients (median age 71) have been treated with GPL, with a median follow up duration of 3.6 months. In prior lines of therapy, 13 patients (35.1%) received treatment more than 2, and 26 patients (70.3%) were with Ann Arbor stage III/IV and 7 patients (18.9%) were refractory to frontline treatment. Previously, 3 patients (8.1%) received CAR-T. Out of 28 evaluable patients, ORR was 89.3%, with CRR of 42.9%. Six-month OS and PFS rate were 81% and 55%. DoR at 6 months was 66%. Neutropenia (45.9%) was the most common grade(gr) 3-4. Three patients (8.1%) died of gr5. There was 1 case (2.7%) of gr3 atrial fibrillation and gr1 bleeding. No incidence of gr3 or above liver/renal toxicity were observed. Overall, 3 patients (8.1%) discontinued GPL treatment due to toxicity, and cytokine release syndrome was observed in 7 patients (18.9%) and only 2 patients (5.4%) were gr3-4. Conclusions: Interim analysis indicates that the GPL regimen is an effective and safe regimen for R/R DLBCL patients. High response rates observed support further investigation of GPL for potential synergism between T-cell engagers and BTKi. This multicenter study is actively recruiting patients and is set to complete enrollment within this year. Clinical trial information: NCT05335018 . [Table: see text]

Risk assessment of cardiovascular adverse events with BTK inhibitors in hematological malignancies: Insights from FAERS.

12145 Background: Burton tyrosine Kinase inhibitors (BTKi) have revolutionized the care of chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphomas (NHL) – including relapsed/refractory mantle cell, ABC diffuse large B cell lymphoma and and lymphoplasmacytic lymphoma. Ibrutinib was the first BTKi to be approved. The newer covalent BTKi include acalabrutinib and zanubrutinib, both of which are approved for frontline and relapsed CLL as well as relapsed NHL. All these agents have cardiovascular adverse events. We aimed to assess the pharmacovigilance (PV), reporting rate, severity, and reaction outcomes of different approved BTKi in the CLL as cancer reported to the United States Food and Drug Administration Adverse Event Reporting System (FAERS). Methods: We analyzed cardiovascular events in 86,370 patients on BTKi. Cardiovascular event reports were submitted to FAERS between 2004-2023 and analyzed using the AERS Mine framework. We compared these incidences within different BTKI. We divided cardiovascular events to three categories: cardiac arrythmia, major coronary or vascular event (MACE) and pericardial complication including effusion or hemorrhage. Our primary composite endpoint was the PV of cardiovascular events caused by BTKI. To mitigate confounding, BTKI were analyzed as mutually exclusive cohorts: Ibrutinib (n = 79,278), acalabrutinib (5200), and zanubrutinib (1354). Two-way ANOVA testing was done to evaluate for statistical significance across the different groups. Results: Across the 86,370 patients on BTKI, we identified 8500 reports of cardiovascular events – ibrutinib (10.15%), acalabrutinib (5.73%), and Zanubrutinib (4.72%). Arrythmia risk was higher with ibrutinib (6.6%) compared to acalabrutinib (3.12%) and zanubrutinib (2.29%). The major difference in the groups was driven by atrial fibrillation (5.1% vs 2.1% vs 1.8%). The MACE rate was 2.79% vs. 2.4% vs. 2%, and pericardial events were 0.72% vs. 0.21% vs. 0.44% in the ibrutinib, acalabrutinib, and zanubrutinib groups, respectively. All the AEs were to have statistical significance (p = 0.011) across all the BTKI as mentioned in table 1. Conclusions: We report the prevalence rate of BTKI-related cardiovascular events in a large cohort of patients. Ibrutinib has demonstrated a higher incidence of toxicity, especially in cardiac arrythmias, while smaller but significant differences exist in other toxicities, including major cardiovascular events and pericardial effusion or hemorrhage. Patient selection and toxicity monitoring are important aspects of the care of these patients, who stay on these therapies for indefinite periods. [Table: see text]

Comparative CNS Pharmacology of the Bruton's Tyrosine Kinase (BTK) Inhibitor Tolebrutinib Versus Other BTK Inhibitor Candidates for Treating Multiple Sclerosis.

Tolebrutinib is a covalent BTK inhibitor designed and selected for potency and CNS exposure to optimize impact on BTK-dependent signaling in CNS-resident cells. We applied a translational approach to evaluate three BTK inhibitors in Phase 3 clinical development in MS with respect to their relative potency to block BTK-dependent signaling and exposure in the CNS METHODS: We used in vitro kinase and cellular activation assays, alongside pharmacokinetic sampling of cerebrospinal fluid (CSF) in the non-human primate cynomolgus to estimate the ability of these candidates (evobrutinib, fenebrutinib, and tolebrutinib) to block BTK-dependent signaling inside the CNS. In vitro kinase assays demonstrated that tolebrutinib reacted with BTK 65-times faster than evobrutinib, while fenebrutinib, a classical reversible antagonist with a Ki value of 4.7 nM and slow off-rate (1.54 x 10-5 s-1), also had an association rate 1760-fold slower (0.00245 μM-1 * s-1). Estimates of cellular potency were largely consistent with the in vitro kinase assays, with an estimated IC50 of 0.7 nM for tolebrutinib against 33.5 nM for evobrutinib and 2.9 nM for fenebrutinib. We then observed that evobrutinib, fenebrutinib, and tolebrutinib achieved similar levels of exposure in non-human primate CSF after oral doses of 10 mg/kg. However, tolebrutinib CSF exposure (4.8 ng/mL) (kp,uu CSF=0.40) exceeded the IC90 (the estimated concentration inhibiting 90% of kinase activity) value, while evobrutinib (3.2 ng/mL) (kp,uu CSF=0.13) and fenebrutinib (12.9 ng/mL) (kp,uu CSF=0.15) failed to reach the estimated IC90 values. Tolebrutinib was the only candidate of the three that attained relevant CSF exposure in non-human primates.

BELLWAVE-011: Phase 3 randomized trial of nemtabrutinib versus ibrutinib or acalabrutinib in untreated chronic lymphocytic leukemia/small lymphocytic lymphoma.

TPS7088 Background: Bruton tyrosine kinase (BTK) inhibitors have significantly improved survival in patients (pts) with chronic lymphocytic leukemia (CLL). Nemtabrutinib is a reversible noncovalent inhibitor of wild-type and C481-mutated BTK that has shown promising antitumor activity in pts with CLL (Woyach JA et al. Cancer Discovery 2023). In this ongoing trial, we evaluate the efficacy and safety of nemtabrutinib versus investigator’s choice of ibrutinib or acalabrutinib in pts with untreated CLL/small lymphocytic lymphoma (SLL) requiring therapy (NCT06136559). Methods: This randomized, open-label, parallel group, active-controlled phase 3 trial will enroll approximately 1200 pts aged ≥18 years. Eligible pts will have confirmed CLL/SLL with active disease based on the IWCLL criteria, which include one of the following: 1) progressive marrow failure or lymphocytosis, 2) massive, progressive, or symptomatic splenomegaly or lymphadenopathy, 3) autoimmune complications, 4) extranodal involvement, or 5) disease-related symptoms. The study will enroll patients who are treatment naïve, with an ECOG performance status 0-2, adequate organ function, and provide blood, bone marrow, and/or a lymph node sample. Pts are excluded if they have Richter Transformation, central nervous system (CNS) involvement by CLL/SLL, an active second malignancy, or a severe bleeding disorder. Pts will be randomized 1:1 to receive oral nemtabrutinib 65 mg QD, or investigator’s choice of oral ibrutinib 420 mg QD or acalabrutinib 100 mg BID. Randomization will be stratified by TP53aberration, clinical stage, investigator’s choice of comparator, and region. Treatment will continue on both arms until unacceptable toxicity, disease progression, or withdrawal. Disease response assessments by physical examination, constitutional symptoms, imaging, and evaluation of blood and bone marrow will be performed Q12W up to week 97, and Q24W thereafter. Primary efficacy endpoints are objective response (OR) and progression free survival (PFS) by BICR per iwCLL 2018 criteria. Secondary endpoints are overall survival (OS), duration of response (DOR) by BICR per iwCLL 2018, and safety. OR will be tested via a non-inferiority comparison, while PFS and OS will be tested for superiority. Adverse events will be monitored throughout the trial and graded per NCI CTCAE v5.0 and iwCLL scales. Enrollment in this trial is ongoing. Clinical trial information: NCT06136559 .

Combination of pirtobrutinib and lentiviral transduced bispecific anti-CD20/CD19 (LV20.19) CAR T-cell therapy to improve outcomes in patients with relapsed/refractory lymphoma.

7043 Background: Combination trials of BTK inhibitors (BTKi) with CAR-T have suggested potential synergistic benefit by improving CAR-T immunophenotype and clinical outcomes but are limited by increased toxicity. We report immunophenotype, cytokine profile, and patient outcomes with the new non-covalent BTKi, pirtobrutinib (pirto) when given prior to LV20.19 CAR-T and compare the final CAR product to pts who did not receive pirtobrutinib prior to CAR. Methods: Pts received LV20.19 CAR-T as part of a phase 1/2 trial (NCT04186520). Only pts who received pirto £4 weeks prior to apheresis were included. To determine the impact of pirto on LV20.19 CAR-T, we calculated both polyfunctionality (PFA) and polyfunctional strength index (PSI) for each product using the Isoplexis. Descriptive statistics, t-tests and Kaplan-Meier method were used as appropriate. Results: 11 pts received pirto prior to LV20.19 CAR-T (Table). Median age was 65 (50-80) yrs and median prior lines of therapy were 4 (2-8). There were 4 MCL pts, 5 Richter’s (RT)/CLL, 1 MZL and 1 DLBCL. Median duration of pirto was 4 (1-20) mo. Pts were on pirto for a median of 12 (1-22) days prior to apheresis. All except 1 pts received target CAR-T dose. The day 28 ORR was 82% (CR=7, PR=2). After a median follow up of 13 mo, 3 pts died (PD, Covid, Guillain Barre). The median PFS and OS were both 30.8 mo while the 1-year PFS and OS rates were 9 and 15 mo respectively. 9 pts had CRS and 2 had ICANS, all grades 1-2, while 4 had IEC-HS. One pt had afib recurrence and 1 pt had CMV viremia within 30 days of CAR-T. Among the pts with immunophenotypic data (n=10), there were no differences in naïve or more differentiated T-cell percentages in apheresis and final CAR-T products when compared to pts who did not receive pirto before LV20.19 CAR-T (n=57). Although not statistically significant, both PFA (CD4=61.8 vs 59, CD8= 49.8 vs 46.9) and PSI (CD4= 1752 vs 1608, CD8=1299 vs 1079) were higher with pirto pre-treated pts, suggesting a potential trend towards improved CAR-T functionality. Conclusions: These data represent the largest experience of pirto prior to CAR-T apheresis and demonstrate that pirto can be safely used as a bridge to LV20.19 CAR-T without negatively impacting their immunophenotype and potentially improving functionality. These data support our planned phase 1 clinical trial to assess the safety of pirto as bridging and maintenance therapy with LV20.19 CAR-T (NCT05990465). [Table: see text]

A single-cell multiomics analysis of IRF4 in mediating treatment resistance in ibrutinib-treated chronic lymphocytic leukemia (CLL).

7051 Background: The Bruton tyrosine kinase (BTK) inhibitor ibrutinib (ibr) has revolutionized the treatment of CLL, showing efficacy in the majority of patients. Nevertheless, resistance occurs in a subset of patients, often with dismal clinical outcomes. Ibr resistance occurs through several mechanisms, including mutations affecting BTK or PLCG2, or upregulation of alternative survival pathways. We investigated at the single-cell level the molecular mechanisms that underlie ibr resistance in CLL cells and their interactions with non-malignant tumor microenvironment (TME) cell populations. Methods: We retrospectively identified 7 CLL patients with ibr resistance (as second line therapy). Samples were obtained before ibr treatment and at progression. Chromium Single Cell Multiome ATAC + Gene Expression (GEX) (10x Genomics) was applied to a mixture of CD19+CD5+ and CD19- cells to jointly analyze DNA accessibility and gene expression in the same single nuclei of CLL B and TME cells. An average of 4,800 cells (range 2,600-15,000) per sample was retained after QC filtering. Principal component analysis (PCA) was performed on GEX counts. ATAC peaks were called with MACS2, and latent semantic indexing was used for dimensionality reduction. We then computed a weighted nearest neighbour graph, identified clusters using the SLM algorithm and performed cell type assignment with established marker genes. Results: We identified 28 distinct cell clusters, representing CLL B-cells or cell types that constitute the TME, including CD4+ and CD8+ T cells, monocytes, dendritic and NK cells. CLL B-cell clusters were patient and timepoint-specific, while TME clusters were occupied by cells from multiple patients. Five patients showed multiple distinct CLL B-cell clusters pre-treatment or at progression, reflecting cellular heterogeneity within the tumor compartment. Interestingly, some clusters that were dominated by post-treatment CLL B-cells also included cells from pre-treatment samples, suggesting pre-existence of the clone giving rise to the relapse. For each patient, we performed pairwise differential expression between CLL B-cell clusters. Gene ontology analysis revealed increased activation of IRF4 and MHC-related pathways in CLL B-cells at progression compared to pre-treatment in 6 and 4 out of 7 patients, respectively. The elevated IRF4 pathway activity was underpinned by increased chromatin accessibility in IRF4 signature genes. Conclusions: Differential blockade of B-cell receptor signaling by ibr has been reported to downregulate activity of IRF4, a key transcription factor in B-cell activation. Our results suggest that CLL B-cells that are resistant to ibrutinib have re-activated IRF4 activity beyond pre-treatment levels, implying a potential role for IRF4 in ibrutinib resistance.

An open label, single arm, multicenter phase II study of the efficacy and safety of LP-168 monotherapy for relapsed or refractory mantle cell lymphoma.

TPS7098 Background: Targeting Bruton’s tyrosine kinase (BTK) has demonstrated impressive efficacy in relapsed or refractory mantle cell lymphoma (R/R MCL). Covalent BTK inhibitors (cBTKi) have produced extended disease remission and durable responses in R/R MCL. However, patients with continuous cBTKi treatment tend to develop selection or outgrowth of resistant clones, which triggers disease relapse. Non-covalent binding BTKi has become a treatment option for patients who progressed on cBTKi. LP-168 is a highly selective next-generation inhibitor of BTK that can bind wild-type BTK covalently and C481-mutated BTK non-covalently (reversibly) Here, we propose to evaluate the safety and efficacy of LP-168 monotherapy in patients with R/R MCL. Methods: NCT05716087 is an open-label, multicenter, single-arm, phase II study to assess the efficacy, safety, tolerability, and pharmacokinetics of LP-168 in Chinese patients with R/R MCL who have failed prior cBTKi treatment. Responses were evaluated using Lugano 2014 criteria. Eligible patients with R/R MCL must show evidence of disease progression or intolerance to at least a prior cBTKi. Patients are also required to have adequate bone marrow, liver function, kidney function, and heart function, and an ECOG performance status of 0-2. Moreover, patients must have at least one measurable lesion. Key exclusion criteria include previous non-covalent BTKi or BTK proteolysis-targeting chimeras (PROTAC) treatment, uncontrolled systemic disease, active infection, central nervous system (CNS) involvement, prior history of other malignancies within two years, and current pregnancy or breastfeeding. Concomitant use of strong or moderate CYP3A4 inducers and inhibitors or OATP1B1/OATP1B3 sensitive substrates is prohibited. LP-168 is orally administered at 150mg once daily in 28-day/cycle until progressive disease (PD), unacceptable toxicity, withdrawal of consent, death, or other reasons for treatment discontinuation. In this study, the primary endpoint was ORR according to an independent review committee (IRC) assessment based on the best overall response (BOR) of PR or better per Lugano 2014 criteria. Secondary endpoints include safety evaluation, quality of life assessment, PK parameters, ORR by investigator’s assessment, and other efficacy parameters, such as complete response ratio (CRR), progression-free survival (PFS), overall survival (OS), duration of response (DOR), and time to response (TTR). First patient was enrolled on May 12, 2023. Currently 41 study sites across China are actively enrolling patients. ClinicalTrials.gov Identifier: NCT05716087. Clinical trial information: NCT05716087 .

Frontline treatment with zanubrutinib plus rituximab (ZR) followed by short course R-DHAOx in patients with mantle cell lymphoma (MCL): Results of the phase II CHESS clinical trial.

7062 Background: Combining Bruton’s tyrosine kinase (BTK) inhibitor and rituximab showed favourable efficacy as first-line therapy for mantle cell lymphoma (MCL). Zanubrutinib, a next-generation, highly-selective BTK inhibitor, achieved promising antitumor activity in MCL. In this multicenter phase II trial (CHESS - chemo-less), we aimed to investigate the efficacy and toxicity of zanubrutinib plus rituximab (ZR) combination, followed by short course cytarabine-based chemotherapy, then zanubrutinib maintenance as frontline therapy for MCL (NCT04624958). Methods: Previously untreated MCL patients enrolled and received induction therapy of ZR until complete response (CR) or to a maximum of 12 cycles, and followed by 4 cycles of R-DHAOx regimen (rituximab, dexamethasone, cytarabine and oxaliplatin). Patients achieving CR after chemotherapy would receive maintenance therapy with zanubrutinib for a maximum of 1 year. The primary endpoint was CR rate after induction therapy with ZR regimen. Minimal residual disease (MRD) of bone marrow and peripheral blood were evaluated by flow cytometry. Results: From Oct 2020 to Nov 2023, a total of 42 patients were enrolled and the enrollment was finished. The median age was 57 years (IQR, 51-64). Stage III-IV accounted for 92.8%, and 42.8% were intermediate or high risk simplified MIPI. Thirty-four patients (81.0%) were classic histological subtype. The median cycle of ZR was 4 (range, 2-6). As of Jan 2024, among 37/42 patients with post-treatment PET evaluation, the best CR rate of ZR regimen was 91.9% (34/37), and 94.1% (32/34) obtained CR after 2-4 cycles. The bone marrow MRD negative CR rate was 92.0% (23/25). The other 5/42 patients were still receiving ZR treatment, and PET evaluation would be performed subsequently. Among 27 patients who finished chemotherapy and were evaluable for response, only one patient experienced disease progression. With a median follow up of 11.6 months, the 1-year progression-free survival and overall survival was 90.1% and 96.7%, respectively. Two patients died due to lymphoma (n=1) and COVID-19 (n=1). Grade 3-4 adverse events on ZR regimen were neutropenia (n=3), fatigue (n=2), and aminotransferase (n=1). During chemotherapy, grade 3-4 thrombocytopenia was observed in 75.8% of patients. Conclusions: Induction treatment with ZR followed by short-course R-DHAOx chemotherapy yielded promising antitumor efficacy. This strategy might reduce the toxicity of cytarabine-based chemotherapy without weakening the therapeutic efficacy. Clinical trial information: NCT04624958 . [Table: see text]

Rituximab, chidamide, and zanubrutinib (ZCR) ± CHOP as a regimen for treatment naive (TN) double-expressor DLBCL (DE-DLBCL).

e19053 Background: DLBCL patients with co-expression of MYC (≥40%) and BCL2 (≥50%) by immunohistochemistry are considered as DE-DLBCL. The prognosis of DE-DLBCL is usually worse than DLBCL-NOS. The Smart Start trial had established the feasibility of chemotherapy-free targeted therapy before 1L chemotherapy. The BTK inhibitor Zanubrutinib (Z) or epigenetic drug Chidamide (C) with R-CHOP regimen has a potential synergistic effect in the treatment of DE-DLBCL. Under the inspiration of Smart Start, this trial aim to explore the feasibility of ZCR±CHOP regimen in TN DE-DLBCL. Methods: This is a multicenter, open-label, single-arm phase 2 study (NCT05527912) conducted in China. If patients achieve complete response (CR) after cycle-2 (C2), ZCR will be continued for up to 8 cycles. Otherwise, ZCR-CHOP will be given for another 6 cycles. The primary endpoint is CR rate at the end of treatment (CRR-EOT); secondary endpoints included ORR (overall response rate) ,2y-PFS, and 2y-OS. Plasma samples were collected at baseline, C2 and the EOT. In evaluable samples, circulating tumor DNA (ctDNA) assays were performed. Results: From February 2023 till now, 34 TN DE-DLBCL patients were enrolled, with 32 patients evaluable. The median age was 52y (range: 22-68), 55.9% were male, 79.4% were Non-GCB (Table 1). 12 patients who achieved CR by C2 were continued with RCZ chemo-free therapy, and CHOP were added to the 14 PR and 3 SD patients. In the 32 evaluable patients, ORR after C2 of RCZ was 81.25% (26/32, CR 37.5%, PR 43.75%, SD 9.4%, PD 9.4%). Up to now, 12 patients have completed 8 courses (C8) and all of them have achieved CR, both ORR and CR are 100% (12/12). 3 patients withdrew due to PD. For safety information in the trial, 64.3% patients reported grade (G)-3/4 AEs. In the Chemo-Free subgroup, only 4 patients (36.4%, 4/11) reported G-3/4 AEs. the majority of G-3/4 AEs is hematological events, including leukopenia, neutropenia and thrombocytopenia. The CR rate at C2 was 66.7% (6/9) in patients with negative baseline ctDNA results. The patients with BCL6 fusion of ctDNA at baseline were more prone to PD (3/4, 75.0%). Compared to baseline, plasma ctDNA levels decreased significantly after C2. 29 patients were evaluable for ctDNA after C2, 100% (12/12) of C2-CR patients and 58.8% (10/17) of non-C2-CR patients were negative, P=0.023. Compared with Non-C2-CR patients, the number of detected mutations and average VAF level were decreased in C2-CR patients. Conclusions: This trial demonstrates ZCR±CHOP could be a promising regimen with active antitumor effect and acceptable toxicity in TN DE-DLBCL patients. Clinical trial information: NCT05527912 .

Financial toxicity (FT), quality of life (QoL), and medication adherence patient-reported outcomes (PROs) in CLL on first-line (1L) oral oncolytics.

e23157 Background: While oral oncolytics have transformed CLL treatment, high costs may cause significant FT adversely impacting patients beyond direct out-of-pocket (OOP) costs. The association of FT with QoL and medication adherence has not been characterized with oral oncolytics in CLL. Methods: Electronic PRO surveys were longitudinally administered to patients initiating any 1L oral oncolytic therapy for CLL within the last 6 months at two academic centers. PROs included FACIT-COST (significant FT: score < 26), FACT-LEU QoL, MARS-5 (suboptimal adherence: score < 25) and PROMIS PMAS to assess medication adherence. PROs were administered at baseline, 3 months, and 6 months after enrollment. Pearson’s correlation ( r) was calculated between PRO domains. Semi-structured, qualitative interviews were conducted after 3-month timepoints and analyzed. Results: 34 patients were enrolled: median age 65 yrs (range 33-80), 59% male, 6% Black, 9% Hispanic. Majority received BTK inhibitors (56%, acalabrutinib/zanubrutinib) followed by venetoclax (44%); 50% received concurrent obinutuzumab. Most had private insurance (50%) followed by Medicare (44%). Median time from 1L initiation to study enrollment: 1.5 months. PRO completion rates: 100% (baseline), 85% (3 mo) and 74% (6 mo). Summarized PRO and interview outcomes are displayed below. Conclusions: Patients with CLL on 1L oral oncolytics experienced worsening FT associated with poor medication adherence and worse QoL over time. PROs were discordant with qualitative interviews and suggested that FT may be driven by factors other than OOP costs. Although funding and patient assistance programs were beneficial, uncertainty over losing funding may be a long-term driver of FT and merits further study. [Table: see text]

Emavusertib (CA-4948) in combination with ibrutinib in patients with relapsed/refractory primary central nervous system lymphoma (R/R PCNSL).

2087 Background: PCNSL is a rare and aggressive form of NHL in the central nervous system or vitreoretinal space. Despite high initial rates of responses to HD-MTX-based induction chemotherapies, most patients relapse in two years. R/R PCNSL is associated with poor prognosis, representing a clear unmet medical need, as there are no currently approved treatments for this disease. IRAK4 kinase activity is required for TLR and IL-1R signaling in a variety of myeloid and lymphoid cell types, including PCNSL. Recruitment of IRAK4 to these receptors and subsequent activation is facilitated by the MyD88 adaptor protein, which is mutated in ~70% of PCNSL. This leads to constitutive activation of the NF-κB signaling pathway, increased inflammation, and tumor growth. Emavusertib is a novel and potent oral inhibitor of IRAK4 and FLT3, which has demonstrated the ability to cross the blood-brain barrier in PCNSL xenografts. In preclinical studies, the combination of emavusertib with ibrutinib overcomes resistance to BTK inhibitors. This combination has an acceptable safety profile across a broad population of R/R NHL patients, including PCNSL. Here we present updated safety and efficacy data for emavusertib in combination with ibrutinib in patients with R/R PCNSL. Methods: The safety, clinical activity, and potential biomarkers of emavusertib in R/R PCNSL are being investigated in the ongoing open-label, Phase 1/2 TakeAim Lymphoma trial (NCT03328078). The eligible patients with R/R PCNSL received emavusertib (100-300 mg BID) in combination with ibrutinib (560 mg QD) in a 21-day cycle until tumor progression or unacceptable toxicity. Results: Here, we present updated data from R/R PCNSL patients with prior ibrutinib exposure who were treated with emavusertib in combination with ibrutinib. The median number of prior lines of anti-cancer therapies was 3 (range: 2-5), all patients were R/R to both frontline therapy and subsequent ibrutinib regimens. Prior responses to ibrutinib based regimens included only 1 CR. Here, we report a higher CR rate when these patients are subsequently treated with emavusertib in combination with ibrutinib.Results revealed no dose-limiting toxicities. Conclusions: Emavusertib in combination with ibrutinib was well tolerated with an acceptable safety profile and promising efficacy in R/R PCNSL patients with previous exposure to ibrutinib (BTKi). Enrollment in this trial is ongoing (NCT03328078). Clinical trial information: NCT03328078 .

Survival benefit of autologous transplant (ASCT) for mantle cell lymphoma (MCL) in the California Cancer Registry (CCR).

e19043 Background: Extended follow up of the prospective Nordic MCL2 cohort shows ASCT in CR1 confers a median OS (mOS) of 12.7 y (Eskelund, BJH 2016). Incorporation of BTK inhibitors in 1L MCL is challenging the role of ASCT in an ongoing prospective trial (TRIANGLE, ASH 2022). The present study aims to evaluate the role of ASCT and the impact of social determinants of health (SDH) in a diverse real-world population of MCL patients. Methods: Adult MCL patients diagnosed from January 1, 2000 to December 31, 2020 in the CCR were identified with ICD-O-3 code 9673. The study was approved by UCLA IRB. OS was estimated using KM statistics, calculated from diagnosis to death/last follow-up. Univariate Cox proportional hazards modeling for lymphoma-specific survival (LSS) was performed for variables of interest; those significant at p ≤ 0.10 were incorporated in a stepwise multivariable regression excluding patients with missing data. Socioeconomic status (SES) variables were reported using census-block group data at diagnosis. Results: 5740 ethnically diverse patients were included (NH Whites, n=4038; NH Black, n=175; Hispanic, n=1057; Asian/Pacific Islanders, n=400). Median age at diagnosis was 69 y (IQR 61–68) and 71% were males. 4096 (71%) and 1346 (23%) patients received chemoimmunotherapy and were treated at an NCI/NCCN center, respectively. With a median follow-up of 33 m (IQR 9–76), mOS of the entire cohort was 4.4 y. ASCT patients (n=652, 11%) had improved mOS compared to non-ASCT (14.2 y vs 3.7 y, respectively p<0.001), and 100-day TRM was 2.5%. In the univariable model for all subjects, age, Charlson Comorbidity Index (CCI), married, chemoimmunotherapy, ASCT, NCI/NCCN center, insurance, period of diagnosis, and community SES, poverty, and education were prognostic for LSS. Race, sex, and rural residence were not associated with LSS. Multivariable analysis of 4148 subjects showed significant predictors of LSS were age ≥ 70 y (HR 1.71, p<0.001), ASCT (HR 0.54, p<0.001), diagnosis after 2013 (HR 0.78, p<0.001), CCI (Ref 0; 1-2 HR 1.22, p<0.001; 3+ HR 1.94, p<0.001), married (HR 0.86, p=0.003), NCI/NCCN treatment center (HR 0.77, p=0.001), higher education (top 40% with high school diploma vs. bottom 20%, HR 0.70, p<0.001), higher overall SES (medium vs. low SES tertile, HR 0.81, p=0.003), and increased community poverty (middle 40% vs. bottom 20%, HR 1.14, p=0.043). Conclusions: Our data represent the largest real-world cohort describing the role of ASCT and SDH in MCL. A minority of patients received ASCT and had improved OS compared to non-ASCT patients. While follow-up of ongoing prospective studies will clarify the role of ASCT using contemporary 1L regimens, the present data suggest ASCT in select patients results in durable response with low TRM. Socially disadvantaged patients should be identified and offered supportive programs early in the disease course to mitigate inferior outcomes.

Orelabrutinib, rituximab, temozolomide and high-dose methotrexate (RMOT) in newly diagnosed primary central nervous system lymphoma (PCNSL): A retrospective analysis on efficacy and safety.

e19041 Background: PCNSL is a rare, aggressive malignant tumor and has a poor prognosis. HD-MTX-based regimen is the first-line treatment of PCNSL. Orelabrutinib is a novel, potent, highly selective BTK inhibitor with a high CSF concentration. Recent evidence has shown the efficacy and safety of orelabrutinib in PCNSL. Therefore, we conducted a retrospective study of clinical outcomes in newly diagnosed PCNSL patients (pts) treated with RMOT regimen in routine clinical care. Methods: This retrospective cohort included the pts (aged 18-80 years) with newly diagnosed PCNSL who received 6 cycles of RMOT regimen (rituximab 375 mg/m2 iv day 1; MTX 3.5 g/m2 iv day 1; temozolomide 150 mg/m2 po day 1 to day 5; orelabrutinib 150 mg qd po; 4 weeks per cycle) as the first-line induction therapy between Nov. 2021 and Aug. 2023. All the pts were proposed to receive orelabrutinib monotherapy as maintenance after RMOT therapy. We recommend to receive autologous stem cell transplantation (ASCT) or whole brain radiation therapy (WBRT) as consolidation after RMOT therapy. Efficacy was assessed by MRI/PET per the International PCNSL Collaborative Group (IPCG) criteria. The primary endpoint was overall response rate (ORR); secondary endpoints were CR rate, progression-free survival (PFS), overall survival (OS), and safety. Results: Ten pts (6 males) with PCNSL were included, with a median age of 61 years (range, 45-77). All pts had a histologically confirmed diffuse large B-cell lymphoma. 4 pts (40%) underwent WBRT after induction therapy. As of the cut-off date (December 31, 2023), the median follow-up time was 9.7 (range, 4.8-25.7) month. All pts were evaluated for the treatment response. An interim evaluation after 4 cycles was available for 10 pts, showing complete remission (CR) rate of 80% (8/10), partial response (PR) rate of 20% (2/10), giving an ORR of 100.0% (10/10, Table). At data cutoff, the best ORR was 100.0% (10/10), with all pts achieved CR. Of 10 responders, 9 had an ongoing response, and 1 died of covid-19 infection. Median PFS/OS was not reached (NR) (95% CI NR-NR). The most common AEs were anemia, other include white blood cell or platelet count decreased. Reported AEs were generally manageable and resolved soon after supportive treatment. Only 1 (10%) pts experienced ≥grade 3 AEs—acute kidney injury. No treatment-related death occurred. Conclusions: This retrospective data suggested that RMOT had an encouraging anti-tumor activity in newly diagnosed PCNSL pts, with a toleratable safety profile. This orelabrutinib-containing regimens may provide a potential treatment strategy for pts with PCNSL. [Table: see text]