Factors associated with second-line triplet therapy in routine care in relapsed/refractory multiple myeloma.

What is known and objectiveSecond-line therapy (SLT) trials in relapsed/refractory multiple myeloma (RRMM) report superior outcomes with triplet combinations. We sought to determine factors associated with triplet SLT in routine practice. MethodsA retrospective cohort with claims for MM between 01/01/2008 and 03/31/2015 was grouped by 1-2 (doublet) or 3+ (triplet) agent therapy. Charlson comorbidity index (CCI) and disability status; CRAB symptoms (hypercalcaemia, renal/bone disease, anaemia); and relapse risk were determined. ResultsAmong 623 patients, the triplet group (n=146 [23%]) was younger (65.2 vs 69.8years) and more likely to have high-risk relapse (67% vs 50%), CRAB symptoms (94.5% vs 81.1%), triplet first-line treatment (75% vs 51%) and frontline stem cell transplant (38% vs 20%) (P<0.001 for all). In multivariate analyses, CRAB symptoms (OR: 3.22, 95% CI: 1.47, 7.10), high-risk relapse (OR: 1.71, 95% CI: 1.12, 2.62) and prior triplet therapy (OR: 2.16, 95% CI: 1.38, 3.40), but neither CCI nor disability, were associated with triplet SLT. A trend towards triplets among younger patients (<65 vs >75years, OR: 1.73, 95% CI: 0.99, 3.04) was observed. What is new and conclusionThe majority of patients did not receive triplet regimens. Treatment selection with triplet therapy for RRMM should carefully consider comorbidities and patient-specific characteristics.