FROM BIOLOGY OF BLOOD AND MARROW TRANSPLANTATION
Undergoing a second allogeneic bone or marrow transplant (BMT) is a feasible strategy for patients who have relapsed after their first transplantation, according to findings reported in Biology of Blood and Marrow Transplantation .
Specifically, there may be an advantage to selecting a donor with a new mismatched haplotype after a failed HLA-matched allograft. Among patients who had a second graft transplanted that did not harbor a new mismatched haplotype, median survival was 552 days (95% CI, 376-2,950+). But median survival was not reached in the cohort whose allograft contained a new mismatched haplotype (hazard ratio, 0.36; 95% confidence interval, 0.14-0.9; P = .02).
“In the case of a failed HLA-matched transplantation, when haplotype loss would not be favored through selective pressure and thus would not provide a mechanism of relapse, switching to a different haploidentical donor may be beneficial by increasing major histocompatibility mismatch,” Philip H. Imus, MD , of the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, and colleagues wrote.
For this retrospective review, the researchers examined 40 consecutive patients who underwent a second BMT for a relapsed hematologic malignancy at a single institution between 2005 and 2014. In all, 21 patients had their first allograft from a haploidentical donor, with 14 of these patients receiving a second haploidentical transplant (8 from a donor sharing the same shared haplotype as the first donor and 6 from a second donor sharing the other haplotype).
The other 19 patients received their first allograft from a fully matched donor, with 14 patients receiving a haploidentical allograft at the second transplantation and 5 receiving a second matched allograft. Overall, a total of 20 patients had a second allograft with a new mismatched haplotype.
The median overall survival for the six patients who were retransplantated with an HLA-haploidentical donor sharing the different haplotype from the first haploidentical donor had not been reached, compared with 502 days (95% CI, 317-2,950+) for the eight patients with a second haplo allograft that shared the same haplotype (HR, 0.37; 95% CI, 0.08 to 1.7; P = .16).
The median event free survival was also superior among those retransplanted with a new mismatched haplotype (not reached vs. 401 days; HR, .50; 95% CI, .22-1.14, P = .09).
A higher risk of mortality was observed in patients who had relapsed within 6 months of their first transplantation (HR, 2.49; 95% CI, 1.0-6.2; P = .07), as well as in those who had progressive or refractory disease prior to their second alloBMT (HR, 2.56; 95% CI, 1.03-6.25; P = .06).
“For patients who relapse more than 6 months after a BMT and who achieve remission with salvage therapy, results are very encouraging,” the researchers wrote. “Although a randomized trial to study selecting donors with a new mismatched haplotype may be impractical, larger numbers should provide additional information on the effectiveness of such an approach.”
The researchers reported having no financial disclosures.
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SOURCE: Imus P et al. Biol Blood Marrow Transplant. 2017;23:1887-94 .
