Background
Final analysis of the randomized phase of phase 3 SYMPATICO (median follow-up 61.3 mo; primary analysis previously summarized). N=267 relapsed/refractory MCL after 1–5 prior lines, randomized 1:1, double-blind. Tests adding BCL2 inhibition to BTK inhibition.
Results
Interventions and follow up: Arm A: ibrutinib 560 mg QD + venetoclax (5-wk ramp-up to 400 mg QD) ×24 mo, then ibrutinib until PD
Arm B: ibrutinib 560 mg QD + placebo ×24 mo, then ibrutinib until PD
Primary endpoint: PFS (investigator-assessed)
mFollow up: 61.3 mo
Results: PFS: median 31.9 vs 22.1 mo; HR 0.63 (95% CI 0.47–0.85), P=.0024
CR rate: 54% vs 32%; rate ratio 1.66, P=.0004
ORR: 82% vs 74%, P=.1279 (NS)
TTNT: median not reached vs 35.4 mo; HR 0.54, P=.0013
OS: median 44.9 vs 38.6 mo; HR 0.83 (95% CI 0.60–1.15), P=.2669 (NS)
TP53-mutated subgroup PFS: 19.8 vs 10.9 mo
Arm B: ibrutinib 560 mg QD + placebo ×24 mo, then ibrutinib until PD
Primary endpoint: PFS (investigator-assessed)
mFollow up: 61.3 mo
Results: PFS: median 31.9 vs 22.1 mo; HR 0.63 (95% CI 0.47–0.85), P=.0024
CR rate: 54% vs 32%; rate ratio 1.66, P=.0004
ORR: 82% vs 74%, P=.1279 (NS)
TTNT: median not reached vs 35.4 mo; HR 0.54, P=.0013
OS: median 44.9 vs 38.6 mo; HR 0.83 (95% CI 0.60–1.15), P=.2669 (NS)
TP53-mutated subgroup PFS: 19.8 vs 10.9 mo
Adverse events
Grade ≥3 (any): 84% vs 76%
Hematologic G≥3: neutropenia 31% vs 11%, thrombocytopenia 13% vs 8%, anemia 10% vs 3%
Infections: pneumonia G≥3 13% vs 11%
GI: diarrhea any-grade 64% vs 36%
Discontinuation for AEs: 32% vs 36%; dose reduction 37% vs 22%
Hematologic G≥3: neutropenia 31% vs 11%, thrombocytopenia 13% vs 8%, anemia 10% vs 3%
Infections: pneumonia G≥3 13% vs 11%
GI: diarrhea any-grade 64% vs 36%
Discontinuation for AEs: 32% vs 36%; dose reduction 37% vs 22%
Conclusions
With ~5 years of follow-up, ibrutinib + venetoclax maintained superior PFS, CR rate, and time to next treatment over ibrutinib alone in R/R MCL, including TP53-mutated disease, with no new safety signals. OS difference remained non-significant.
Key Limitations
No OS benefit (HR 0.83, NS). Comparator is ibrutinib monotherapy, no longer a US option (voluntarily withdrawn for MCL 2023) — relevance vs pirtobrutinib, brexu-cel, or 1L BTKi-treated patients is unclear (see accompanying BJH commentary). Continuous ibrutinib design; largely pre-CAR-T sequencing era.
Clinical Context
Ibrutinib + venetoclax is not FDA-approved in MCL; the combination's future likely lies with next-generation BTKis (e.g., acalabrutinib/zanubrutinib + venetoclax). In the US, R/R MCL standards center on covalent BTKis, pirtobrutinib post-BTKi, and brexucabtagene autoleucel. This entry supplements the previously filed SYMPATICO primary analysis.