Results of phase 2 trial suggest that the use of abatacept in patients receiving unrelated-donor (URD) hematopoietic cell transplantation (HCT) was associated with improvements in acute graft-versus-host disease (aGVHD) and severe aGVHD-free survival (SGFS). Trial results were reported in the Journal of Clinical Oncology.

In this phase 2 trial (ABA2; ClinicalTrials.gov identifier: NCT01012492) examining use of abatacept, patients of all ages with hematologic malignancies were enrolled into 1 of 2 study cohorts. All patients received a calcineurin inhibitor and methotrexate in addition to their study treatment, and day +100 grade 3 or 4 aGVHD was the primary study endpoint for both cohorts.

One cohort of 148 patients was randomized 1:1 to receive either abatacept or a placebo control. This cohort consisted of patients who received 8/8 human leukocyte antigen (HLA)-matched URD HCT. In the second cohort, 43 patients received abatacept in a single study arm, with results compared to those of a separate, prespecified control cohort not given abatacept. The single-arm cohort consisted of patients who received URD HCT with a 7/8 level of HLA matching.


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In the randomized cohort, 73 patients received abatacept, and 69 received the placebo. The rates of grade 3 or 4 aGVHD in this cohort were 6.8% for patients who received abatacept and 14.8% for those given a placebo (P =.13) at day 100. In the single-arm cohort, at day 100 the rate of grade 3 or 4 aGVHD with abatacept was 2.3% in the intention-to-treat population, compared with a rate of 30.2% from the prespecified control cohort (P <.001).

The rate of SGFS (at day 180) was 93.2% for patients receiving abatacept in the randomized cohort, and it was 82% for those receiving the placebo (P =.05). For patients receiving abatacept in the single-arm cohort, the SGFS rate was 97.7%, compared with the rate of 58.7% for the prespecified control cohort (P <.001).

The study investigators concluded that use of abatacept appeared safe while showing improved rates of aGVHD and SGFS, especially for patients with 7/8 URD HCT, about whom they wrote “the addition of abatacept could be clinical practice-changing for these otherwise high-risk transplants.”

Disclosures: Some authors declared affiliations with or received funding from the pharmaceutical industry. Please refer to the original article for a full list of disclosures.

Reference

Watkins B, Qayed M, McCracken C, et al. Phase II trial of costimulation blockade with abatacept for prevention of acute GVHD. J Clin Oncol. Published online January 15, 2021. doi:10.1200/JCO.20.01086