Racial and ethnic differences in safety, efficacy, and outcomes among patients who were treated with idecabtagene vicleucel (ide-cel) were reviewed by Lauren C Peres, PhD, MPH, and colleagues at the 64^th American Society of Hematology Annual Meeting and Exposition during their presentation “Racial and Ethnic Differences in Clinical Outcomes Among Multiple Myeloma Patients Treated with CAR T Therapy.”

Their study was prompted by the recent FDA approval of the chimeric antigen receptor (CAR) T-cell therapy ide-cel for treatment of relapsed/refractory multiple myeloma (RRMM). While treatment responses to ide-cel were notable in the KarMMa clinical trial, racial and ethnic minorities were underrepresented in the trial population.

"KarMMa showed remarkable overall response rates – 73% overall response rate, 33% complete response. Now that CAR T-cell is available as standard of care, these therapies are offering renewed hope to this patient population which had few treatment options remaining,” Dr Peres said. “There remains a question as to whether all racial and ethnic groups experience the same benefit from ide-cel and it’s hard to know from what has been published because race and ethnicity were not reported consistently in key clinical trials. And when they were reported, it seems that racial and ethnic minority patients have been largely underrepresented in clinical trials.”

The researchers used data from 207 RRMM patients across 11 sites who were treated with standard of care (SOC) ide-cel; they then investigated differences in patient and clinical characteristics, standard inflammatory laboratory values, immune-mediated toxicities, cytopenias, and treatment responses using chi-square and Kruskal-Wallis rank sum tests. Overall survival (OS) and progression-free survival (PFS) were examined by race and ethnicity using Kaplan-Meier survival curves and log-rank tests.

The data showed that the median age at infusion was 64 years (range, 36-83 years); 34% of patients presented with high-risk cytogenic abnormalities; 45% had extramedullary disease; 43% had penta-refractory disease; and six prior lines of therapy was the median (range 3-19) before ide-cel infusion.

Of the 215 RRMM patients treated with SOC ide-cel, 150 (70%) self-identified as non-Hispanic White individuals, 36 (17%) as non-Hispanic Black individuals, and 21 (10%) as Hispanic. Additionally, 8 (3%) self-identified as Asian, Pacific Islander, American Indian, or Alaskan Native, though this group was excluded from the study due to limitations in the sample size.

Black patients were more likely to be female compared to non-Hispanic White patients and Hispanic patients (58% vs 38% vs 29%, respectively, P = .04) and were more likely to have higher levels of baseline inflammatory markers. Additionally, compared to non-Hispanic White patients and Hispanic patients, non-Hispanic Black patients were more likely to develop cytokine release syndrome of any grade, have longer hospital stays, and experience Grade ≥3 prolonged cytopenias.

Compared to non-Hispanic White patients, those who self-identified as Hispanic and non-Hispanic Black combined showed a worse PFS (median PFS 9.0 vs 5.9 months; P = .08).

“Non-Hispanic Black individuals have two times the incidence of multiple myeloma compared to all other racial and ethnic groups,” Dr Peres said. “In population-based data, we see that survival is actually a little bit better for non-Hispanic Black patients, but the same population-based data shows that non-Hispanic White patients have benefitted from these survival improvements due to these novel therapies but not as much for Black patients.

“Non-Hispanic Black and Hispanic patients are less likely to receive transplant and novel therapies, they have a longer time from diagnosis to treatment initiation, and they’re underrepresented in clinical trials.”

No racial or ethnic differences were found in OS, nor were other differences observed by race and ethnicity in patient and clinical characteristics, standard inflammatory laboratory values, immune-mediated toxicities, and treatment responses.

While the small sample size and newness of ide-cel are limitations of the study, Dr Peres said continued studies are planned.

“Our patient population was 207 and 28% were racial and ethnic minorities. It’s critical that we re-evaluate these findings as more patients are treated with ide-cel and as follow-up time matures,” she said. “And we plan to do exactly that. Early in 2023, we’re going to have a consortium database update where we’re going to re-evaluate these findings. We also plan on looking at other factors that might be important contributors to disparities, such as looking at area-level measures of socio-economic status and other characteristics that might contribute to disparities as well.”

Peres L, Oswald L, Dillard C, et al. Racial and Ethnic Differences in Clinical Outcomes Among Multiple Myeloma Patients Treated with CAR T Therapy. Presented at: 64th ASH Annual Meeting and Exposition; December 10-13, 2022. Abstract 252.