Characteristics and Outcome Of Multiple Myeloma (MM) In African Americans (AA) Receiving Novel Agents and Autologous Stem Cell Transplantation (ASCT)

African Americans (AAs) have a higher incidence of MM, about twice as much as Caucasians, and present at a younger age. Several studies have shown that presentation and outcomes of AA are similar to Caucasians treated with standard and high dose chemotherapy. The impact of induction with novel agents (IMIDs and proteosome inhibitors) and prognostic markers such as cytogenetics on different ethnic groups has not been fully evaluated.

We analyzed MM patients (AA=174 and Caucasians= 279) who underwent auto-SCT over fifteen years (1998-2013). Baseline characteristics are summarized in table below. Patients received induction therapy with standard chemotherapy (n=33) or dexamathesone (n=43) before 2001 or IMIDs or protesome inhibitors in addition to either chemotherapy (n=72) or dexamethasone (n=203) when treated after 2001. All patients received high-dose melphalan followed by auto-SCT. Response criteria were assessed according to the International Uniform Response criteria.

Table.

Patients' Characteristics at diagnosis

*≥ VGPR/PR/PD; more than very good partial response, PR; partial response, PD; progressive disease.

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AA were significantly younger but with no differences in disease stage or CRAB criteria at MM diagnosis with the exception of anemia. More AA women were referred and underwent auto-SCT relative to AA men. The subtype distribution was significantly different between AA and Caucasians (P <0.001). FISH and cytogenetics data for hyperdiploidy, hypodiploidy, deletions in chromosome 13q, 17p and 1p and IgH translocations were available for 271 patients. Approximately two-thirds of the patients had normal or favorable cytogenetics with more hyperdiploidy present in AA, although the population of patients with hyperdiploidy (43) is small for definitive conclusions. Response to induction was similar between AA and Caucasians, however response to novel agents plus dexamethasone was significantly better in Caucasians (p = 0.02). There was no difference in PFS between AA and Caucasians (median of 2.6 years; 95% CI: 2-3); In contrast, OS was significantly better in AA (median 7.7; 95% CI: 6.5-9.8) versus Caucasians (median 6.2; 95% CI: 5.5-7.5).

MM is heterogeneous disease. AA disease characteristics are different from Caucasians (subtype and cytogenetics). AA have inferior responses to novel agents, despite comparable and probably better survival to Caucasians, suggesting a favorable disease biology. Future studies focusing on AA patients are urgently needed to validate these observations prospectively.

No relevant conflicts of interest to declare.