Black race linked to inferior outcomes among younger patients receiving CAR-T for ALL
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Younger Black patients who received tisagenlecleucel for acute lymphoblastic leukemia had significantly poorer outcomes than those of other races or ethnicities, according to results presented at TCT Meetings Digital Experience.
Results of the retrospective study also showed that younger Black patients more often did not receive a planned infusion of tisagenlecleucel (Kymriah, Novartis) — an autologous, gene-edited, CD19-directed chimeric antigen receptor T-cell therapy — due to manufacturing failure or other conditions.
“Our group was interested in collecting data because we know historically there have been outcome disparities based on race and ethnicity — particularly among Black and Hispanic patients,” Christina Baggott, RN, PhD, PPCNP-BC, CPON, clinical trials nurse practitioner in the cancer clinical trials office at Stanford University School of Medicine, told Healio. “Once we were able to compile data from Black patients and compare it with all others, that's when we saw some significant findings.”
Those findings included Kaplan-Meier survival curves that showed Black patients had “dramatically” inferior survival rates compared with other patients, she added.
Baggott and colleagues used data compiled by the Pediatric Real World CAR Consortium, which includes 15 centers nationwide that provide CAR T-cell therapy. The researchers collected data on children and adolescents with relapsed or refractory ALL who had apheresed cells shipped for commercial tisagenlecleucel manufacturing.
Examining outcomes of younger Black patients with ALL who received the therapy served as the study’s objective.
The study cohort included 200 patients, of whom 46.5% were “non-Hispanic white.” The remainder were Hispanic (37.5%), Black (5.5%), Asian (4.5%), multiracial (2.5%), or unknown race or ethnicity (3.5%).
The low representation of Black patients highlights one of the study’s limitations, Baggott said.
“This may indicate that these patients are not being referred for CAR-T as often or that Black patients may not be accepting of CAR-T as a treatment option,” she said.
Black patients had more previous lines of therapy (median, 5 vs. 2; P < .0001), more relapses before CAR-T (median, 2 vs. 1; P = .0105) and a higher rate of prior stem cell transplantation (71% vs. 24%; P = .0122) than other patients in the study. They also appeared more likely to be diagnosed when they were infants (27% vs. 7%; P = .0468).
Fifteen patients did not undergo infusion of tisagenlecleucel after apheresis. They included 36.4% of Black patients in the cohort (four of 11), compared with only 5.8% of patients (11 of 189) of other races and ethnicities (P = .005). Two of the Black patients did not undergo infusion because of manufacturing failure after apheresis.
The efficacy analysis showed a complete response rate of 57% among Black patients compared with 86% for all other patients who received tisagenlecleucel (P = .007).
OS rates among Black patients were significantly lower at 6 months (43% vs. 86%) and 1 year (43% vs. 73%) compared with all other patients in the study (P for both = .026).
Multivariate analysis identified Black race as a predictor of OS (HR = 3.36, P = .05). Variables in the analysis included age at diagnosis, previous hemopoietic stem cell transplant, disease burden at the time of infusion, and time from diagnosis until infusion.
Black patients had lower leukemia-free survival rates at 6 months (43% vs. 64%) and 1 year (29% vs. 52%) than the rest of the cohort (P = .081).
“Knowing that disparities typically exist among Hispanic patients, we did an analysis of that cohort and did not find a significant difference in survival after CAR-T therapy,” Baggott told Healio.
This lack of an association for Hispanic patients was “intriguing” and should be a point of emphasis for further study, she said.
In addition to the low representation of Black patients in the study, Baggott acknowledged that race data were taken from electronic medical records, which could introduce a level of cultural bias. When trying to determine relationships between race/ethnicity and treatment outcomes, she said it is important to obtain the demographic information directly from the patient.
“Race can often have cultural differences that affect outcomes; it's not always about the biological aspects that lead to disparities based on race and ethnicity,” she said.
Given the size of the cohort and its limitations, no concrete conclusions can be made about the association between race and outcomes, Baggott said. However, she said these results provide a launch point for further study of its validity, as well as cytogenetic and cultural factors that may contribute to disparities in treatment and outcomes.
The data Baggott and colleagues collected may lack equitable geographic distribution because of the location of the 15 member institutions, which tends to underrepresent rural areas and the Southern region of the United States. A prospective trial being planned includes 25 centers thus far, she said.
“Hopefully that study will be more representative of the U.S. population,” she added.
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Baggott C, et al. Abstract LBA7. Presented at: The 2021 TCT Meetings Digital Experience (virtual meeting); Feb. 8-12, 2021.
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