Phase I Trial of Brentuximab Vedotin for Steroid-Refractory Chronic Graft-Versus-Host Disease after Allogeneic Hematopoietic Cell Transplantation

Abstract We conducted a phase I study of brentuximab vedotin (BV), an antibody-drug conjugate targeting CD30, for the treatment of steroid-refractory chronic graft-versus-host disease (cGVHD). A modified 3+3 study design was used with the primary endpoint to determine the maximum tolerated dose (MTD) of BV in this population. Escalating doses of BV were planned, starting with 0.6 mg/kg q3weeks (dose level 0) and increasing by 0.3 mg/kg per dose level. BV was administered in 21-day cycles for up to 16 cycles of therapy. Nineteen patients were enrolled on the study, with 2 withdrawing consent prior to dosing. The median number of cycles of therapy was 4 (range, 1-16). Reasons for stopping therapy prematurely included toxicities (n=9), patient decision (n=3), lack of response (n=2), and death (n=1). There were 2 DLTs observed: PRES (cohort 4, grade 3) and sepsis (cohort 4, grade 4). The MTD was not reached as the trial was prematurely closed due to toxicity. Seven patients (41%) developed grade 3 or 4 adverse events that were attributed to therapy, including 4 patients who developed moderate or severe peripheral neuropathy that led to cessation of treatment in each case. According to NIH cGVHD Response Criteria, 8 patients (47%) experienced a partial response while 9 patients (53%) had a lack of response. There were no complete responses observed. Eleven patients (65%) were able to decrease their systemic corticosteroid dose by ≥50% by 6 months after initiation of BV, including 3 patients who were able to stop corticosteroids completely. The median soluble CD30 level prior to therapy was 61.5 ng/mL (range, 7.8-474.9), however, we did not observe any association between soluble CD30 level and cGVHD severity at enrollment or clinical responses to BV. In conclusion, BV may have activity in treatment of steroid-refractory cGVHD, yet its use is limited by treatment-emergent toxicities, including peripheral neuropathy. Continued efforts to investigate targeted approaches to cGVHD that do not cause broad immunosuppression are needed.