Treatment Efficacy in Relapsed/Refractory Multiple Myeloma: Outcomes Based on Racial Disparity
Authors: Jabbour Hiba , Ramo Aula Rita , Donthireddy Vijayalakshmi 
Published: October 2019

Abstract
Introduction:
There have been major advances in the diagnosis, staging, risk-stratification, and management of multiple myeloma (MM). Novel triplet regimens containing drugs such as Carfilzomib, Elotuzumab, Daratumumab, or Ixazomib have improved the median progression-free survival rates at first relapse to approximately two years. This retrospective study analyzes the responses and survivals of treatment regimens used at first relapse in the real world setting and attempts to evaluate any differences in outcomes based on race.
Methods:
We reviewed the charts of all patients with relapsed/refractory or progressive multiple myeloma who were treated for first relapse or progression at Henry Ford Hospital in Michigan. Patients who received a combination regimen with any of the following medications: Bortezomib, Lenalidomide, Pomalidomide, Ixazomib, Carfilzomib, Daratumumab, and Elotuzumab between 1/1/2015 and 4/24/2018 were included. Baseline characteristics data using the electronic medical record was retrieved for age, sex, race, performance status, cytogenetics, previous treatment, progression free survival and compared based on race. Patients were excluded if they did not receive treatment for relapse, expired prior to initiating relapse treatment or were lost to follow up.
Results:
A total of 300 patients were treated with systemic therapy for multiple myeloma, 140 of whom had relapsed/refractory or progressive disease. We excluded 28 patients who did not meet inclusion criteria. The remaining 112 patients were treated for first relapse or progression of myeloma and were included in our study cohort. Patients characteristics are shown in table 1.
Out of those 112 patients, 26 (23.2% of the cohort) received a novel triplet regimen for their first relapse, 21 (18.8%) received an older triplet regimen, 14 (12.5%) received a novel doublet regimen, 44 (39.3%) received an older doublet regimen and the remainder 7 patients (6.3%) received other regimens as detailed in table 2.
Of the 26 patients who received a novel triplet regimen, 11 were African American and 15 were White. Ten patients had disease progression or death at the time of data analysis and qualified for progression free survival (PFS) calculation. The remaining 16 patients were still receiving their treatment regimen at the time of analysis. Progression free survivals comparing novel triplet regimens based on patients race are shown in table 2. Of note, median PFS for Carfilzomib, lenalidomide, dexamethasone (KRd) regimen was 26.3 months in the ASPIRE trial and 20.6 months for Ixazomib, lenalidomide, dexamethasone regimen in the TOURMALINE-MM1 trial. The 12-month rate of PFS for Daratumumab, bortezomib, dexamethasone (DVd) regimen was 60.7% in the CASTOR trial, 83.2% for Daratumumab, lenalidomide, dexamethasone (DRd) regimen in the POLLUX trial and 68% for Elotuzumab, lenalidomide, dexamethasone regimen in the ELOQUENT-2 trial.
Of the 21 patients who received an older triplet regimen, 9 were African American, 11 were White and 1 was Hispanic. All of them had disease progression or death and qualified for PFS calculation.
Of the 44 patients who received an older doublet regimen, 27 were African American, 15 were White and 2 were Hispanic. Thirty two patients had disease progression or death at the time of data analysis.
Of the 14 patients who received a novel doublet regimen, 9 were African American and 5 were White. Eight had disease progression or death at the time of data analysis. These results are shown in table 2.
Conclusion:
Our retrospective cohort study shows a distribution of the treatment regimens used for the management of relapsed multiple myeloma. Progression free survivals for a novel triple drug regimen for myeloma at first relapse seems to be shorter in the real world setting than published data. Specifically, when compared based on race, African American patients had worse outcome overall with shorter progression free survival period. However, data is limited due to the small number of patients. Stratification based on race or focused trials for certain populations such as African American are needed to manage this challenging disease.

Disclosures
No relevant conflicts of interest to declare.