Differences in Presentation and Survival Outcomes for African American Patients with Newly Diagnosed Multiple Myeloma

Background: Though the incidence of MM is two- to threefold higher in the African American (AA) population compared to Caucasians, reported long term outcomes are less favorable presumably due to inequities in access to healthcare. Little is known about the biology or disease presentation among AAs. We have conducted a retrospective analysis of our institutional data of 1000 patients treated with RVD induction therapy, specifically assessing differences in presentation, disease biology, and outcomes in AA patients.

Methods: A total of 1000 newly diagnosed MM patients were treated with RVD induction therapy [R - 25 mg/day (days 1-14), V - 1.3 mg/m2 (days 1, 4 8, 11) and D - 40 mg once/twice weekly as tolerated every 21 days] from January 1^st 2005 until August 31^st 2016. Dose-adjustments were made based on the treating physician's discretion and patient tolerability. Demographic and outcomes data for the patients were obtained from our IRB approved myeloma database and responses were evaluated per IMWG Uniform Response Criteria.

Results: Of the 1000 patients included in the analysis, 564 (56.4%) of patients were white (W), and 339 (33.9%) were AA, consistent with the demographic representation of the state of GA and our institutional referral population. Median age of this cohort was 61 years (range 16-83), 57 for AA patients (range, 24-83) compared to 62 (range, 16-81) in white patients, suggesting the onset is earlier among AA which has been previously reported in population based studies. Other notable characteristics include: 42.5%M/57.5% F for AA cohort and 61.7%M/38.3%F for white cohort. In regard to stage, AA: 73.9% stage I/II, 26.1% stage III; W: 77.1% stage I/II, 22.9% stage III, showing no difference in prognostic staging at presentation. There was no statistically significant difference in the presenting labs between AA and whites except for hemoglobin, with more AA patients presenting with Hgb≤9.9 g/dL (45.7% AA vs 32.5% W, p <.0001).

In terms of prevalence of high-risk cytogenetics, there was no significant difference between the two cohorts in: complex karyotype 16% white/14.4% AA; t(14;16) 2.4% W/2.8% AA; t(4;14) 4.7% W/5.0% AA; t(11;14) 11.7% W/15.9% AA; or del1p 6.5%W/7.8%AA. However, there were significant differences found in the rates of: amp 1q 19.2% W/10.6% AA, (p<.0001), del13 28.3% W/19.6% AA (p=.003), and del17p 11.7% W/7.2% AA (p=.019), all three significantly less frequent in AAs.

Median time to transplant for the entire cohort was 5 months (range, 1-124), and median time to best response was 3 months (range, 0-39). There was no significant difference in the number of patients who underwent ASCT (84% W vs 82% AA, p=.241), nor in ≥VGPR rates post-induction and 100 days post-ASCT: 69.9% W vs 64.5% AA (p=.056) and 88.1% W vs 86.7% in AA patients (p=.317), respectively.

Median PFS for the entire cohort was 63 months, 62 months (54-69.9) for white patients versus 65 months (53-76.9) for AA patients (p=0.403). At a median follow up of 38 months, median OS has not yet been reached.

Conclusions: This is the largest reported cohort of myeloma patients treated with RVD induction, with one-third of the patients representing the AA population. In our dataset, AAs are diagnosed 5 years younger, with lower hemoglobin at presentation and lower rates of amp1q, del13 and del17p when compared to whites. When offered the same induction regimen and opportunity for ASCT, AAs tend to experience the same survival benefits as their white counterparts. The lack of significant difference in PFS or OS suggests standardization and improved access to care could lead to better long-term outcomes in the AA population.

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