The study also found, however, that transplant outcomes appear to be worse for Black African American patients who have primary myelofibrosis (PMF), although the study utilized a small sample size.
Black African American patients with primary myelofibrosis (PMF) have similar survival rates compared with non–African American patients, according to the findings from a new study published in Blood Advances. However, they also appear to have worse outcomes following allogeneic stem cell transplantation (ASCT) and are more likely to relapse.
This study is believed to be the first to compare the clinical phenotype, genotype, and outcomes of African American patients and non–African American patients with PMF.
The authors noted that myelofibrosis is a type of myeloproliferative neoplasm that can progress to acute myeloid leukemia (AML). Previous evidence suggests that Black patients with AML had a higher risk of death vs White patients, and an analysis of Medicare data shows the survival of Black patients with 2 other types of myeloproliferative neoplasms—essential thrombocythemia and polycythemia vera—was inferior to that of non-Black patients, although the same was not true for PMF. Other studies comparing White patients and non-White patients have had conflicting conclusions regarding survival outcomes.
For these reasons, the investigators wanted to better characterize the clinical phenotype and genotype of Black African Americans with PMF and to see how the long-term survival of African-American patients compared with non–African American patients.
To find out, they looked at the cases of 88 consecutive African American patients who were treated at 3 United States cancer centers between March 1998 and March 2022. Recruitment was retrospective, but the investigators updated patient follow-up in October 2022. They then compared those patients with a cohort of 1266 non–African American patients from a Mayo Clinic study published in 2019. Patients were screened for common mutations and categorized based on prognosis score, risk profile, and karyotype.
The 88 African American patients had a median age of 61, and 52% were female. Among the non–African American patient cohort, the median age was 65 years and just 37% were female. Patients in the Black African American cohort were also more likely to have palpable splenomegaly and to be in the low- or intermediate-1 risk categories according to Dynamic International Prognostic Scoring System (DIPSS) and DIPSS-plus scoring.
Among the 63 African American patients for whom driver mutation information was available, 68% had JAK2 mutations, 19% had CALR mutations, 8% had MPL mutations, and 5% of patients were triple-negative, meaning they had none of those mutations. Of 70 patients for whom karyotype categorization was possible, 80% had a favorable karyotype, 14% had an unfavorable karyotype, and 6% were categorized as very high risk.
The most common therapies for the 70 African American patients for whom data were available were hydroxyurea (31 patients) and ruxolitinib (Jakafi; 28 patients). Nine patients (10%) in the Black African American cohort underwent ASCT compared with 67 patients (5%) in the non–African American cohort. However, posttransplant survival was worse in the African American cohort, with a median of just 1.3 years vs 11.3 years in the non–African American cohort. Moreover, 4 of the 9 African American patients who received transplants experienced a relapse compared with 15% of the patients in the non–African American cohort.
At a median follow-up of 3.2 years, the median overall survival (OS) for African American patients was 4.8 years, which was not significantly different from the 4.4 years in the non–African American cohort.
“Overall survival was found to be similar between African American and non–African American patients,” the study authors wrote. “On the other hand, posttransplant outcomes were inferior in the African American cohort likely due to differences in donor source, with significantly greater utilization of haplo-identical or mismatched transplants in African American patients.”
The investigators noted, however, that they had a small sample size of African American patients who underwent ASCT, so is not possible to draw definitive conclusions.
They added that their study is the first of its kind to examine differences in characteristics and outcomes between African American patients and other patients with PMF.
“Additional studies on race-related discrepancies in transplant outcomes with a focus on conditioning regimens, incidence of graft versus host disease, and relapse are warranted,” they concluded.
Gangat N, Kuykendall AT, Al Ali NH, et al. Black African-American patients with primary myelofibrosis: a comparative analysis of phenotype and survival. Blood Adv. Published online February 13, 2023. doi:10.1182/bloodadvances.2022009611