Pb2010: retrospective study of relapsed/refractory myeloma patients from an indian tertiary centre: response matters!!

Background: Treatment paradigm of relapsed multiple myeloma (MM) has changed in the last decade. We report treatment outcomes among relapsed MM patients in the era of proteasome inhibitors (PI) and newer immunomodulatory drugs (IMiDs) in an Indian cohort. Aims: The primary objective was to determine the progression free survival (PFS) of relapsed patients. Secondary objectives include complete response rates (CR) & objective response rates (ORR), (≥ partial response (PR)). Methods: The study is a retrospective review of relapsed MM patients treated at a North Indian tertiary cancer referral center between January 2014 to December 2019 and were subsequently followed till October 2021 for outcomes. Patients who relapsed after atleast one prior line of therapy were included. Records of 300 patients were screened and 195 (65%) patients were included in the study. 105(35%) patients with incomplete treatment details and significant missing data were excluded. Results: Median age was 58 years (range; 51 to 65 years). 108 (55.4%) patients had an IgG subtype. High risk features observed were renal failure in 16% patients, extramedullary disease in 9% patients. Bortezomib based triplet in 27.6% of patients followed by combination of bortezomib with IMiD based triplet in 25.1% patients followed by pomalidomide based regimen (without PI) in 15.3% and doublet regimen were used in 15.3%. Responses were evaluable in 176 patients. ORR in the entire cohort was seen in 98/176 (55.6%) patients. Among the individual regimens, it was 66% with bortezomib based triplet, 58% with bortezomib & IMiD based regimen. Complete response (CR) was seen in 19/176 (10.8%) patients. After a median follow up of 11.5 months (range; 5.5-25.6 months), 143 (73.3%) patients progressed. Median PFS of the entire cohort was 8 months (range, 0-55.0 months). Median PFS did not differ by type of salvage treatment used (p-value= 0.7). Multivariate cox proportion analysis suggested that patients achieving CR had better PFS (median 31.2 months [95% CI 10.1-55.9] vs 6·9 months [1.61, 36.2]; hazard ratio (HR) 3.07 [95% CI 1.34,7.01], two-sided p=0·005). Similarly achieving a response 5.09 v 11.4 months, ([HR], 95% CI; 15.1 (5.59, 41.0), p value <0.001). Median OS was not reached during the study duration. Toxicities were managable with serious adverse events noted in 2% of patients. Image:Summary/Conclusion: In relapsed myeloma patients we suggest that depth of response, and acheiving a CR irrespective of drugs used in salvage regimen predict a better PFS. To date this is the largest retrospective series from an Indian center. However, these findings require validation by a randomized control trial.