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

Second-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.

A 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.

Among 623 patients, the triplet group (n=146 [23%]) was younger (65.2 vs 69.8 years) 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 >75 years, OR: 1.73, 95% CI: 0.99, 3.04) was observed.

The majority of patients did not receive triplet regimens. Treatment selection with triplet therapy for RRMM should carefully consider comorbidities and patient-specific characteristics.