Study Summary: The Role of Race and Ethnicity in Disease and Outcome Disparities in Multiple Myeloma

Ailawadhi S, Jacobus S, Sexton R, et al. Disease and outcome disparities in multiple myeloma: exploring the role of race/ethnicity in the Cooperative Group clinical trials. Blood Cancer J. 2018;8(7):67. doi: 10.1038/s41408-018-0102-7.

Each year, approximately 30,000 Americans are diagnosed with multiple myeloma (MM), making it the second most commonly diagnosed hematological malignancy in the United States. Over time, the prevalence of MM has increased, with a progressively younger median age of diagnosis. Rapidly improving treatment options for MM has improved survival rates over the past 10 years, with 5-year survival rates approaching approximately 50%. However, questions abound regarding the role of race and ethnicity in MM, particularly with respect to survival rates.

The analysis reported below evaluates patient-level data from published Eastern Cooperative Oncology Group (ECOG)-ACRIN/South West Oncology Group (SWOG) and sought to further investigate these racial differences.1

Study Design
This analysis included data from 9 previously published ECOG-ACRIN/SWOG clinical trials. Data collected on the patients enrolled in these trials included baseline demographics, clinical features, and MM characteristics. Clinical trials were grouped pertaining to fixed duration versus treatment given until progression, with or without stem cell transplantation, and treatment with a novel agent (ie, proteasome or immunomodulatory drug). Patients were separated into the following race-ethnicity categories: non-Hispanic whites, non-Hispanic African Americans, non-Hispanic others, and Hispanics. Investigators evaluated the relationship between race-ethnicity, and clinical outcomes, including progression and death.1

Baseline Characteristics
The final cohort included 2896 patients. The majority of patients were male (58.5%) and the median age was 61.4 years. Additionally, 81.9% were non-Hispanic whites, 13.5% were non-Hispanic African Americans, 2.6% were Hispanics, and 1.9% were non-Hispanic others. International Staging System (ISS) stage was only available for 2427 patients. Of these patients, 71.4% were stage I–II and 28.6% were stage III. A total of 63.9% of patients had lytic bony lesions. With regard to common laboratory parameters, 96.2% did not have hypercalcemia and 86.8% did not have any critical elevations in serum creatinine. Overall, 39.4% of patients had significant anemia. The number of patients who had an available body-mass index was 1261, and of those patients, 40.7% were overweight and the remaining 25.4% obese.1

Patient Characteristics by Race. Significant differences among race-ethnicity groups were observed with regard to median age at diagnosis (P <.001), gender (P = .002), overweight/obese (P = .0018), significant anemia (P <.001), and lactate dehydrogenase (P = .011). In regard to ECOG performance status, there were no serious differences with ISS stage, presence of absence of lytic bony lesions, bone marrow plasmacytosis, serum calcium, or creatine levels.1

Patient Participation in Clinical Trials by Race-Ethnicity. Significant differences among racial-ethnic subgroups for all clinical trial characteristics were observed with regard to enrollment in clinical trials (P <.001), treatment with novel anti-MM products (P = .047), stem cell transplantation trials (P = .034), and fixed duration treatment versus treatment to progression trials (P = .001).1

Outcomes by Patient Characteristics Other Than Race-Ethnicity. The study cohort was censored at 6 years and yielded 2375 progression events and 1782 deaths. Progression-free survival (PFS) was moderately stronger for females versus males and was significantly worse for patients ≥70 years, those having an ECOG performance status >0, and patients who were ISS stage III. With regard to laboratory parameters, PFS was much worse for patients with hemoglobin ≤10 g/dL and for those with serum creatinine ≥2 mg/dL. All of these parameters were also associated with significant differences in overall survival (OS), except with more profound results.1

Outcomes by Patient Race-Ethnicity. There were no significant results noted for response rates for the primary endpoints of clinical trials. Median PFS for the entire study population was 2 years and the median OS was 4.2 years.1

Among patients in the analysis, only 18% were non-white and the enrollment of minorities were found to decrease in most recent years. Overall, African-Americans were younger and included frequent poor-risk markers (eg, anemia and increased lactate dehydrogenase). Hispanics had the fewest number of patients enrolled in the trials that utilize novel therapeutic agents. Although certain demographic and clinical factors (ie, increased age, ECOG performance status, ISS stage, presence of anemia, and kidney dysfunction) were compared with decreased survival, patient race-ethnicity did not significantly effect response rates, PFS, or OS. The authors noted that “improved minority accrual in therapeutic clinical trials” needed to be a priority.1

1. Ailawadhi S, Jacobus S, Sexton R, et al. Disease and outcome disparities in multiple myeloma: exploring the role of race/ethnicity in the Cooperative Group clinical trials. Blood Cancer J. 2018;8(7):67. doi: 10.1038/s41408-018-0102-7.
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