Pharmacyclics LLC today announced interim results from the ongoing Phase Ib/II PCYC-1129 study suggesting that ibrutinib (IMBRUVICA®) may be a safe and effective treatment for patients with chronic graft-versus-host-disease (cGVHD) who were either refractory to steroid treatment or were steroid-dependent. The data will be presented today at the 51st American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, IL at 8:00 a.m. CT. IMBRUVICA is jointly developed and commercialized by Pharmacyclics and Janssen Biotech, Inc.
Lead investigator David Miklos, M.D., Ph.D., Stanford University, Stanford, CA, presented the data in full in a poster session.
cGVHD is a life-threatening condition in which newly transplanted cells attack the patient's body. Patients may develop this common complication after undergoing allogenic stem cell or bone marrow transplantation. There are currently no therapies specifically approved for this condition.
The ongoing Phase Ib/II study evaluated the safety and efficacy of ibrutinib for the treatment of patients with steroid-dependent or refractory cGVHD. The Phase Ib portion of the study was open-label and designed to determine the recommended Phase II dose of ibrutinib, starting at 420 mg. Six patients (median age 56 years, median Karnofsky score 85) were enrolled in the Phase Ib portion. The median time from transplant was 23 months and the median time on ibrutinib was 19.3 weeks. The Phase II study is currently ongoing.
"Patients and physicians alike have long been searching for safe and effective non-steroidal options to treat this condition," said Danelle James, M.D., M.S., Head of Oncology at Pharmacyclics. "The initial data presented today provide compelling results that support the potential of ibrutinib as a promising therapy for chronic GVHD."
In a preliminary analysis, data show all five evaluable patients who had received at least three months of ibrutinib achieved a partial response (PR), and two patients who were evaluable at six months maintained a PR. Improvements in clinician-assessed GVHD-score, skin erythema (4 PRs at three months and one complete response [CR]) and mouth score (4 PRs at three months and 1 case of stable disease) were observed in patients during the initial analysis. Early pharmacokinetic data in the patients were within range with exposure in indications currently included in the IMBRUVICA product label. Overall, ibrutinib showed early clinical activity in the reduction of cGVHD based on the NIH consensus cGVHD Activity Assessment. As a result of the preliminary evaluation of the available data, researchers determined the Phase II dose of ibrutinib to be 420 mg.
The most common treatment-emergent adverse events (AEs) in this study included fatigue (n=5), diarrhea (n=4), ecchymosis or bruising (n=3) and stomatitis (n=2), all of which were Grade 1 or 2. Serious AEs (SAEs) occurred in two patients and included Grade 3 pneumonia, as well as pyrexia and fungal brain abscess; the latter was the only event leading to ibrutinib discontinuation, which occurred at 10.9 weeks. No dose-limiting toxicities were reported in Phase Ib.