Background
Phase 3, open-label, randomized controlled factorial trial (UK Myeloma Research Alliance). N=2042 newly diagnosed multiple myeloma patients from the United Kingdom. Two factorial randomizations: (1) induction therapy (thalidomide-based vs cyclophosphamide-based), and (2) maintenance: lenalidomide maintenance vs observation after induction ± ASCT, including an optional intensification randomization for transplant-eligible patients (carfilzomib vs no intensification).
Interventions and follow up
Arm A: Lenalidomide 10 mg PO daily (days 1–21 of a 28-day cycle), continuous maintenance until progression or unacceptable toxicity, following induction and optional ASCT
Arm B: Active observation/no maintenance following induction and optional ASCT
Primary endpoint: Progression-free survival (lenalidomide maintenance vs observation)
Median follow up: 31 months (primary analysis); longer with updated analyses
Arm B: Active observation/no maintenance following induction and optional ASCT
Primary endpoint: Progression-free survival (lenalidomide maintenance vs observation)
Median follow up: 31 months (primary analysis); longer with updated analyses
Results
PFS (maintenance comparison): HR 0.44 (95% CI 0.36–0.54), P<.0001; median PFS ~39 mo vs ~20 mo
OS (updated analysis): HR 0.78 (95% CI 0.62–0.98), P=.03
Response deepening: 52% vs 33% achieved a deeper response on maintenance vs observation
OS (updated analysis): HR 0.78 (95% CI 0.62–0.98), P=.03
Response deepening: 52% vs 33% achieved a deeper response on maintenance vs observation
Adverse events
Hematologic/infection (grade ≥3): Neutropenia 25.6% vs 6.5%; infections 18.6% vs 7.6%
Second primary malignancies/discontinuation: SPM 5.2% vs 2.2% (haematological SPM increased); discontinuation for toxicity ~23%
Second primary malignancies/discontinuation: SPM 5.2% vs 2.2% (haematological SPM increased); discontinuation for toxicity ~23%
Conclusions
Continuous lenalidomide maintenance significantly improved PFS (HR 0.44) and, at extended follow-up, demonstrated an OS benefit (HR 0.78) in both transplant-eligible and transplant-ineligible NDMM patients, cementing lenalidomide maintenance as a standard of care after induction ± ASCT.
Key Limitations
The factorial design, while efficient, complicates interpretation of individual treatment effects. The trial was open-label. Lenalidomide maintenance was given indefinitely until progression, raising questions about cumulative toxicity and impact on subsequent therapy. The observed increase in second primary malignancies (particularly haematological) is a clinically relevant concern. Results from this UK-based trial may have different generalizability compared with US populations.
Clinical Context
Myeloma XI confirms the OS benefit of lenalidomide maintenance seen in IFM 2005-02 and CALGB 100104. Current ESMO guidelines recommend lenalidomide maintenance post-ASCT for eligible patients. The optimal duration (2 years vs continuous) remains debated, with data from multiple trials supporting at least 2 years. For transplant-ineligible patients, the maintenance benefit persisted across subgroups in this trial.