Real World Treatment Patterns and Toxicity Among Elderly Patients with Multiple Myeloma

Introduction: Multiple Myeloma (MM) is a disease of the elderly; with approximately two-thirds of cases diagnosed at ages older than 65 years. However, this population has been underrepresented in clinical trials. Hence, there are no evidence-based guidelines to select the most appropriate treatment that would balance effectiveness against risk for side effects in the real world. Currently, guidelines advise that doublet regimens should be considered for frail, elderly patients; but more detailed recommendations are lacking. This study aims to describe treatment patterns in older patients with MM and compare treatment response and side effects between doublet and triplet regimens.

Methods: Patients diagnosed with MM at 70 years or older and treated at Montefiore Medical Center between 2000 and 2017 were identified using Clinical Looking Glass, an institutional software tool. Recipients of autologous stem cell transplant were excluded. We collected demographic data and calculated comorbidity burden based on the age-adjusted Charlson Comorbidity Index (CCI). Laboratory parameters included cell blood counts, renal function, serum-protein electrophoresis and free kappa/lambda ratio pre and post first-line treatment. Treatment was categorized into doublet [bortezomib/dexamethasone (VD) and lenalidomide/dexamethasone (RD)] or triplet regimens [lenalidomide/bortezomib/dexamethasone (RVD) and cyclophosphamide/bortezomib/dexamethasone (CyborD)]. Disease response was reported as VGPR, PR, SD or PD using pre-established criteria. Side effects included cytopenias, diarrhea, thrombosis and peripheral neuropathy. Clinical and laboratory data were obtained by manual chart review. Event-free survival was defined as time to treatment change, death or disease progression. Data were analyzed by treatment group using Stata 14.1

Results: A total of 97 patients were included, of whom 46 (47.4%) were males, 47 (48.5%) were Non-Hispanic Black and 23 (23.7%) were Hispanic. Median age at diagnosis was 77 years (range: 70-90). Median baseline hemoglobin was 9.4 (8.5-10.5) and 14 (16.1%) had grade 3/4 anemia. Baseline thrombocytopenia and neutropenia of any grade were less common (18.4% and 17.7%, respectively) and 11 patients (20%) had GFR ≤30. Treatment regimens included VD (51, 52.6%), CyborD (18, 18.6%), RD (15, 15.5%) and RVD (13, 13.4%).

Overall, doublets were more commonly used than triplets (66, 68% vs 31, 32%). Baseline characteristics were similar among treatment regimen groups. There was no difference in treatment selection among patients with baseline anemia or baseline neutropenia; however, doublets were preferred for those with underlying thrombocytopenia compared to triplets (93.8% vs 6.2%, p<0.01). Median first-line treatment duration was 4.1 months and did not differ among treatment groups (3.9 vs. 4.3 months; p=0.88 for doublets and triplets, respectively). At least a partial response was achieved in 47 cases (63.5%) and it did not differ between doublets and triplets (61.7% vs 66.7%). In general, first line treatment was changed in 50 (51.5%) patients and the change frequency was higher for triplets than doublets (71% vs 42.4%, p<0.01). Among patients that changed treatment, 17(34.7%) switched from a doublet to a triplet; 15 (30.6%) from a triplet to a doublet and 17 (34.7%) changed the regimen remaining as doublet or triplet, respectively. There was no difference in frequency of cytopenias, diarrhea, thrombosis or peripheral neuropathy among groups. Median event-free survival was longer in patients receiving doublet vs. triplet therapy, although the difference was not statistically significant (7.3 vs 4.3 months; p=0.06).

Conclusions: We show a real-world experience of an inner city, elderly MM cohort, ineligible for autologous transplantation. A doublet combination and specifically the VD regimen was the treatment of choice in the majority of cases. In this cohort, triplet regimens did not show better response rates and led to treatment change more often than doublets. Among patients requiring treatment, approximately a third switched from doublet to triplet or viceversa which suggest that current evaluation of patient frailty at diagnosis is suboptimal. Despite similar frequency of side effects among groups, there was a trend towards longer event-free survival in patients receiving doublets. Larger retrospective studies are needed to confirm these results.