Roos-Weil, Damien

Abstract Waldenström macroglobulinemia (WM) is characterized by recurrent MYD88 and CXCR4 mutations, whose prognostic value in patients treated with chemoimmunotherapy remains unclear. Moreover, the typically prolonged progression-free survival (PFS) correlates inconsistently with overall survival (OS), underscoring the importance of examining other surrogates. Progression of disease within 24 months (POD24), an established early end point, delineates functionally high-risk patients in other indolent lymphomas. This international study evaluated 253 patients receiving frontline fixed-duration bendamustine-rituximab (BR), a common chemoimmunotherapy for WM. At a median follow-up of 5.9 years, 5-year PFS and OS were 65% and 87%, respectively; 5-year PFS was similar between MYD88L265P (90%) and MYD88wild-type (WT) subcohorts (64% each; P = .4). Among 89 patients with known CXCR4 status, the subcohort with CXCR4mutation (28%) had shorter PFS (median 3.3 vs 8.8 years; hazard ratio [HR], 2.8; P = .0036) and OS (HR, 2.6; P = .036) compared with CXCR4WT. POD24 occurred in 11.5% of patients who demonstrated inferior subsequent OS (5-year OS, 71% vs 86%; HR, 3.1; P = .005) and higher mortality (standardized mortality ratio [SMR], 3.7), unlike the non-POD24 group, whose mortality was comparable to the matched general population (SMR, 1.1). In conclusion, BR is effective irrespective of the MYD88 status, but CXCR4 mutations and POD24 portend worse outcomes. Patients without POD24 represent a cohort with distinctly favorable outcome.

Abstract Introduction: The prognosis of patients (pts) with histological transformation (HT) of Waldenström macroglobulinemia (WM) remains dismal with standard chemoimmunotherapy. CD19-targeted chimeric antigen receptor T-cell therapies (CAR-T) can lead to durable responses in relapsed/refractory (R/R) large B-cell lymphoma (LBCL) and are approved in the second or third line settings. Pts with HT-WM were largely excluded from CAR-T trials. We previously reported high response rates in a series of 23 pts. The aim of the present study was to evaluate a larger cohort of pts with R/R HT-WM treated with CAR-T with a longer follow-up. Methods: We performed a multicenter retrospective study of pts with biopsy-proven transformed WM/lymphoplasmacytic lymphoma treated with CAR-T in the French DESCAR-T registry (NCT04328298), 4 centers from ECWM and 4 US centers. This study includes updated data from previously published cases (Durot et al, Blood, 2024). Responses were assessed according to the Lugano 2014 criteria. Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) were graded according to the ASTCT 2019 consensus criteria. Hematological toxicity and infections were graded according to the NCI CTCAE (version 5.0). Progression-free survival (PFS) and overall survival (OS) were calculated from the date of CAR-T infusion and estimated using the Kaplan-Meier method. Results: 50 pts were included (39 from DESCAR-T centers, 7 from US centers and 4 from ECWM centers). Median age was 60 (range: 32-72) and 68 (range: 42-82) years at WM diagnosis and CAR-T infusion, respectively. MYD88L265P and CXCR4 mutations were present in 79% (23/29) and 15% (2/13) of patients with available data, respectively. The median time from WM to HT diagnosis was 5.3 years (range: 0-32). Median prior lines of therapy was 1 (range: 0-9) for WM and 2 for HT (range: 0-4). Twenty (40%) pts previously received a BTK inhibitor for WM or HT, 12 (24%) underwent prior autologous SCT and 1 pt allogeneic SCT. 40% of pts presented primary refractory disease and 44% were refractory to last treatment before CAR-T. 40 pts (80%) received bridging therapy, of whom 17 (44%) responded (7 complete responses (CR)). 35 (70%), 10 (20%), and 5 (10%) pts received axicabtagene ciloleucel (axi-cel), tisagenlecleucel (tisa-cel), and lisocabtagene maraleucel (liso-cel), respectively. The best overall response rate (ORR) was 94%, with 44 (88%) pts reaching CR. With a median follow-up of 25.7 months (range: 1-69) from CAR-T infusion, the median PFS was 1.2 years (95% CI: 0.5-4.5) and median OS was 4.2 years (95% CI: 1.2-not reached). Median duration of response was 1.5 years (95% CI: 0.4-4.4), with a median of 4 years (95% CI: 1.5-NR) for pts still in CR at 6 months after CAR-T. 22 pts experienced relapse/progression after CAR-T, 19 related to LBCL and 3 to WM. Median survival after relapse was 7.9 months (95% CI: 3.8-25.3). At LBCL relapse after CAR-T, salvage therapy consisted of CD20xCD3 bispecific antibodies for 9 pts, lenalidomide +/- anti-CD20 or anti-CD19 antibody for 6 pts, and BTKi for 3 pts. Among 19 pts who died, 14 (74%) were due to progressive disease and 5 (26%) from infections. 37 (76%) pts experienced CRS, including 2 (4%) grade 3 events, and 22 (45%) had ICANS, with 2 (4%) ≥ grade 3 events. 17 (35%) pts presented infections, including 12 ≥ grade 3. 21 (43%) pts developed ≥ grade 3 prolonged cytopenias (ie, not resolved within 30 days post infusion). CNS involvement due to LBCL was present in 11 pts (22%) at the time of CAR-T. 6 of them had ICANS, with 1 grade 4. The best ORR was 91% (best CR 91%). Only 1 patient did not obtain a response, with stable disease at 1 month and progression at 3 months. The median PFS was 1.2 year (95% CI: 0.2-NR) and median OS was NR (95% CI: 0.5-NR). On univariate analysis, only elevated LDH was correlated with worse PFS (HR 2.5, p=0.04) and OS (HR 3.3, p=0.04). Other variables, including number of prior lines of therapy, MYD88 mutation status, primary refractory disease, refractory to last treatment, CNS involvement before CAR-T, response after bridging therapy and type of CAR-T received, were not associated with inferior PFS or OS. Conclusion: This cohort represents the largest series of pts with transformed WM treated with anti-CD19 CAR-T. We confirm the high efficacy previously reported with an acceptable safety profile, including for pts with CNS involvement due to LBCL at CAR-T infusion.

Abstract Introduction: BGB-16673 is an orally available protein degrader that blocks BTK signaling by tagging BTK for degradation through the cell's proteasome pathway, leading to tumor regression. CaDAnCe-101 (BGB-16673-101; NCT05006716) is an ongoing open-label, phase 1/2 study evaluating BGB-16673 monotherapy in patients with B-cell malignancies. Here, updated safety and efficacy results of BGB-16673 are presented in patients with WM in the phase 1 portion of the study. Methods Eligible patients had confirmed relapsed/refractory (R/R) WM (≥2 prior therapies), an ECOG performance status of 0-2 (0-1 in the EU), and previous treatment with an anti-CD20 antibody and, in the US, Japan, and EU, a covalent BTK inhibitor. BGB-16673 was dosed once daily orally. The primary objectives of this phase 1 study were to evaluate safety and tolerability (NCI-CTCAE v5.0) and establish the maximum tolerated dose and recommended dose for expansion. A secondary objective was to evaluate the overall response rate (ORR; modified IWWM-6 consensus criteria), with the first assessment after 4 weeks of treatment. Results As of May 23, 2025, 42 patients with WM were enrolled and treated (100 mg, n=15; 200 mg, n=14; 350 mg, n=13). Median age was 72.0 years (range, 46-81 years), and the median number of prior therapies was 3 (range, 2-11), including prior covalent BTK inhibitors (n=42 [100%]), BCL2 inhibitors (n=10 [23.8%]), noncovalent BTK inhibitors (n=7 [16.7%]), anti-CD20 monoclonal antibodies (n=42 [100%]), and chemotherapy (n=39 [92.9%]). In total, 33.3% of patients (12/36) had WM with BTK mutations, 85.7% (36/42) with MYD88 mutations, 51.3% (20/39) with CXCR4 mutations, 52.8% (19/36) with TP53 mutations, and 5.6% (2/36) with PLCG2 mutations. Median follow-up was 8.8 months (range, 0.8-31.0 months). Overall, 97.6% of patients experienced treatment-emergent adverse events (TEAEs) of any grade (grade ≥3, 59.5%; serious TEAEs, 35.7%). The most common (≥20% incidence) TEAEs (any grade; grade ≥3) were neutropenia (38.1%; grade ≥3, 33.3%, most common grade ≥3 TEAE), diarrhea (26.2%; no grade ≥3), contusion/bruising (26.2%; no grade ≥3), and thrombocytopenia (21.4%; grade ≥3, 7.1%). No atrial fibrillation was observed. Grade 3 febrile neutropenia and major hemorrhage (grade 3 hematemesis caused by concurrent gastritis/duodenitis unrelated to treatment) occurred in 1 patient (2.4%) each. Seven patients (16.7%) had a grade ≥3 infection, including 2 patients with fungal infections. Three patients (7.1%) had TEAEs that led to treatment discontinuation (anemia, cerebral aspergillosis, pericardial effusion/pleural effusion; n=1 each), and 2 patients (4.8%) had a TEAE that led to dose reduction. Two patients (4.8%) died due to TEAEs (septic shock in the context of progressive disease [PD] and cerebral aspergillosis; n=1 each). All 42 patients were response-evaluable and the ORR (minor response [MR] or better) was 83.3% (n=35), the major response rate (partial response [PR] or better) was 64.3% (n=27), and the very good partial response (VGPR) rate was 26.2% (n=11). Median time to first overall response was 1.0 months (range, 0.9-3.8 months) and to best overall response was 1.9 months (range, 0.9-7.4 months). Responses deepened over time: of 9 patients with stable disease at first disease assessment, 3 transitioned to MR and 2 to PR; of 20 patients with initial MR, 10 transitioned to PR and 2 to VGPR; and of 13 patients with initial PR, 7 transitioned to VGPR. Thirty patients (71.4%) remain on treatment. Two deaths were due to PD. Responses were seen in patients previously treated with a covalent BTK inhibitor (35/42 [83.3%]) and a noncovalent BTK inhibitor (7/7 [100%]) and in patients who discontinued a prior BTK inhibitor due to PD (28/35 [80%]). Responses were independent of mutations in BTK (with, 12/12; without, 17/24), MYD88 (with, 30/36; without, 5/6), CXCR4 (with, 18/20; without, 14/19), TP53 (with, 16/19; without, 13/17), and PLCG2 (with, 1/2; without, 28/34). The 9-month duration of response rate was 84.1% (95% CI, 63.1%-93.7%). Conclusions Data from this ongoing phase 1 study demonstrate that the novel BTK degrader BGB-16673 was well tolerated and continued to show substantial antitumor activity in patients with heavily pretreated BTK inhibitor–exposed R/R WM, including those with BTK, MYD88, CXCR4, and TP53 mutations. Enrollment is ongoing in the phase 2 portion of the study.

Abstract Introduction: BTK inhibitors are effective treatments for CLL/SLL; however, treatment intolerance and resistance to BTK inhibitors are major clinical challenges for many patients. BGB-16673 is an orally available protein degrader that blocks BTK signaling by tagging BTK for degradation through the cell's proteasome pathway, leading to tumor regression. CaDAnCe-101 (BGB-16673-101; NCT05006716) is an ongoing open-label, phase 1/2 study evaluating BGB-16673 monotherapy in patients with B-cell malignancies. Here, updated phase 1 safety and efficacy data are reported for patients with relapsed/refractory (R/R) CLL/SLL. Methods: Eligible patients must have confirmed R/R CLL/SLL (≥2 prior therapies), an ECOG performance status of 0-2 (0-1 in the EU), and adequate organ function. In the US, EU, and Australia, patients must have previously received a covalent BTK inhibitor (cBTKi). Patients received BGB-16673 once daily orally. The primary phase 1 objectives were to assess safety/tolerability (NCI-CTCAE v5.0; iwCLL hematologic toxicity criteria) and to establish the maximum tolerated dose and recommended dose for expansion. A secondary objective was to assess overall response rate (ORR) per iwCLL 2018 criteria with partial response with lymphocytosis (PR-L) modification and per 2014 Lugano criteria for SLL, with the first response assessment after 12 weeks of treatment. Results: As of May 23, 2025, 67 patients with CLL/SLL were enrolled and treated (50 mg, n=1; 100 mg, n=22; 200 mg, n=17; 350 mg, n=15; 500 mg, n=12). Patients had a median age of 70 years (range, 47-91 years) and a median of 4 prior lines of therapy (range, 2-10), including cBTKis (n=63 [94.0%]), BCL2is (n=55 [82.1%]), and noncovalent BTK inhibitors (ncBTKis; n=14 [20.9%]). At study baseline, 65.7% (44/67) of patients had CLL/SLL with del(17p) and/or TP53 mutation, 77.6% (38/49) with unmutated IGHV, 38.1% (24/63) with BTK mutation, and 15.9% (10/63) with PLCG2 mutation. Median study follow-up was 18.0 months (range, 0.3-31.0 months); 39 patients (58.2%) remained on treatment at the data cutoff. Overall, 95.5% of patients had any-grade treatment-emergent adverse events (TEAEs); any-grade TEAEs in ≥25% of patients were fatigue (37.3%), contusion/bruising (31.3%), diarrhea (28.4%), and neutropenia (28.4%). Grade ≥3 TEAEs occurred in 62.7% of patients; grade ≥3 TEAEs in ≥5% of patients were neutropenia (23.9%), pneumonia (10.4%), and thrombocytopenia (6.0%). Eight patients (11.9%) had a TEAE leading to dose reduction. TEAEs led to treatment discontinuation in 12 patients (17.9%), three (4.5%) of whom had treatment-related TEAEs (subdural hemorrhage, maculopapular rash, and disseminated aspergillosis). Four patients (6.0%) had TEAEs that led to death (all due to infections, including 1 fungal infection); no deaths were deemed related to treatment. In 66 response-evaluable patients (1 patient on treatment did not reach the first assessment by the data cutoff), ORR (PR-L or better) was 86.4% (n=57), with a 4.5% (n=3) complete response (CR)/CR with incomplete marrow recovery rate. At 200 mg, ORR was 93.8% (15/16), including 1 CR. The median time to first response was 2.8 months (range, 2.0-19.4 months). Thirty-three patients (49.3%) remained on treatment for ≥12 months. Responses deepened over time: of 22 patients with initial PR-L, 15 transitioned to partial response (PR); of 16 patients with initial stable disease, 1 transitioned to PR-L and 10 to PR. Responses were seen in patients previously treated with a cBTKi (53/62 [85.5%]) or ncBTKi (10/14 [71.4%]), with double (cBTKi and BCL2i; 39/42 [92.9%]) and triple exposure (cBTKi, BCL2i, and ncBTKi; 9/12 [75.0%]), with (18/24 [75.0%]) and without (36/39 [92.3%]) BTK mutations, with del(17p) and/or TP53 mutation (35/43 [81.4%]), and with PLCG2 mutation (9/10 [90.0%]). The 12-month progression-free survival rate was 79.2%; 15 patients (22.4%) had progressive disease (2 associated with Richter transformation to diffuse large B-cell lymphoma), and 4 (6.0%) died. Further exploratory analyses will be presented at the meeting.Conclusions: Data from the ongoing CaDAnCe-101 study demonstrate that the novel BTK degrader BGB-16673 has a tolerable safety profile and shows robust and deepening responses in patients with heavily pretreated R/R CLL/SLL, including those with prior BTK inhibitor treatment and BTK mutations. The 200-mg dose of BGB-16673 is being evaluated in phase 2 and 3 studies in patients with R/R CLL/SLL.