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

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 of BV in this population. Escalating doses of BV were planned, starting with .6 mg/kg every 3 weeks (dose level 0) and increasing by .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 before dosing. The median number of cycles of therapy was 4 (range, 1 to 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 dose-limiting toxicities observed: posterior reversible encephalopathy syndrome (cohort 4, grade 3) and sepsis (cohort 4, grade 4). The maximum tolerated dose was not reached because 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 National Institutes of Health cGVHD response criteria, 8 patients (47%) experienced a partial response, whereas 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 before therapy was 61.5 ng/mL (range, 7.8 to 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.