Background
Phase 3, double-blind, placebo-controlled randomized controlled trial (HELIOS). N=578 patients with R/R CLL/SLL after ≥1 prior line (idelalisib- and ibrutinib-naive). All received bendamustine + rituximab (BR) backbone. Randomized 1:1 to ibrutinib vs placebo added to BR for 6 cycles, then ibrutinib/placebo monotherapy until progression. Required ECOG PS ≤2, adequate organ function; del(17p) patients excluded from primary cohort.
Interventions and follow up
Arm A: Ibrutinib 420 mg PO daily + bendamustine 70 mg/m² days 1–2 + rituximab 375 mg/m² cycle 1 then 500 mg/m² cycles 2–6 → ibrutinib maintenance until progression
Arm B: Placebo + bendamustine + rituximab → placebo maintenance
Primary endpoint: PFS (investigator-assessed)
Median follow-up: 17 months
Arm B: Placebo + bendamustine + rituximab → placebo maintenance
Primary endpoint: PFS (investigator-assessed)
Median follow-up: 17 months
Results
PFS: Not reached vs 13.3 months, HR 0.203, P<.001
ORR: 82.7% vs 67.8%, P<.001
CR/CRi: 10.4% vs 2.8%
OS: HR 0.628 (95% CI 0.385–1.024) — not significant at interim (crossover permitted)
PFS (del17p subgroup): HR 0.24 — consistent benefit
ORR: 82.7% vs 67.8%, P<.001
CR/CRi: 10.4% vs 2.8%
OS: HR 0.628 (95% CI 0.385–1.024) — not significant at interim (crossover permitted)
PFS (del17p subgroup): HR 0.24 — consistent benefit
Adverse events
Hematologic: Grade ≥3 neutropenia 54% vs 44%; febrile neutropenia 14.5% vs 12.1%; overall grade ≥3 AEs 67% vs 60%
Cardiovascular: AFib any grade 7.3% vs 2.4%; major hemorrhage 4.5% vs 2.1%
GI: Diarrhea grade ≥3 3.8% vs 1.4%
Discontinuation due to AEs: 21% vs 14%
Cardiovascular: AFib any grade 7.3% vs 2.4%; major hemorrhage 4.5% vs 2.1%
GI: Diarrhea grade ≥3 3.8% vs 1.4%
Discontinuation due to AEs: 21% vs 14%
Conclusions
Ibrutinib added to bendamustine-rituximab significantly improved PFS in R/R CLL/SLL versus placebo-BR (HR 0.203), with benefit across all prespecified subgroups including del(17p). However, BR as a backbone is increasingly anachronistic in the venetoclax era.
Key Limitations
The BR backbone is rarely used in R/R CLL today, where venetoclax ± anti-CD20, BTKi monotherapy, or non-covalent BTKi (pirtobrutinib) are preferred, limiting contemporary relevance. OS data were immature with crossover. No head-to-head comparison with venetoclax + rituximab (MURANO) or novel BTKi combinations. Short follow-up (17 months). The ibrutinib + BR combination has not been widely adopted.
Clinical Context
HELIOS supported FDA approval of ibrutinib + BR for R/R CLL in 2016, but this combination has been largely supplanted by continuous ibrutinib monotherapy, venetoclax + rituximab (MURANO), and venetoclax + obinutuzumab. In BTKi-intolerant or BTKi-refractory patients, ASCEND and MURANO offer alternative strategies, and pirtobrutinib (BRUIN CLL-321) is now standard for BTKi-pretreated R/R CLL. ESMO-MCBS: not assigned.