A Phase I Study of Pelabresib (CPI-0610), a Small-Molecule Inhibitor of BET Proteins, in Patients with Relapsed or Refractory Lymphoma.

Purpose: NF-κB, a transcription factor essential for inflammatory responses, is constitutively activated in many lymphomas. In preclinical studies, pelabresib (CPI-0610), an investigational (BET) bromodomain inhibitor, downregulated NF-κB signaling and demonstrated antitumor activity in vitro. Here we report the safety, pharmacokinetics, pharmacodynamics, and preliminary clinical activity from the first-in-human phase I study of pelabresib in patients with relapsed/refractory lymphomas (NCT01949883). Experimental Design: Sixty-four patients with relapsed/refractory lymphoma (median of 4 prior lines of therapy) were treated with either capsule (6, 12, 24, 48, 80, 120, 170, 230, 300 mg) or tablet (125, 225 mg) doses of pelabresib orally once daily on a 14 days on, 7 days off schedule. Results: The MTD was determined as the 225 mg tablet daily. The most frequent adverse events were fatigue, nausea, and decreased appetite. Thrombocytopenia, a class effect for all BET inhibitors, was dose-dependent, reversible, and noncumulative. Pelabresib exhibited dose-proportional increases in systemic exposure, rapid absorption, and a half-life of approximately 15 hours (supporting once daily dosing). The bioavailability of the tablet formulation was 60% greater than the capsules. Pelabresib suppressed IL8 and CCR1 mRNA at doses above 120 and 170 mg, respectively. Four patients (6.2%) had an objective response (2 complete response and 2 partial response) and 5 patients had prolonged stable disease. Conclusions/Discussion: Pelabresib is capable of BET target gene suppression in an exposure-dependent manner with an acceptable safety profile leading to the recommended phase II dose of the 125 mg tablet once daily. Significance: BET proteins inhibition can potentially modify the pathogenic pathways which contribute to many diseases including malignancies. Pelabresib (CPI-0610), a potent and selective small molecule BET proteins inhibitor, has a MTD of 225 mg once daily for 14 days with a 7-day break, clear pharmacokinetic/pharmacodynamic relationship, and manageable clinical safety profile. These findings are part of the foundation for the ongoing pivotal study of pelabresib in patients with myelofibrosis.

Randomized, Ascending Dose, Phase 2 Study of KHK4083, an Anti-OX40 Monoclonal Antibody, in Moderately Active Ulcerative Colitis.

Background: OX40 (CD134) plays a role in the maintenance of late T-cell proliferation and survival. KHK4083 is a monoclonal antibody directed against OX40. We aimed to assess the safety and preliminary efficacy of KHK4083 in patients with moderately active ulcerative colitis (UC). Methods: In this multicenter, double-blind, parallel-group, phase 2 study, patients with moderately active UC patients were randomized to ascending doses of intravenous KHK4083 (1, 3, or 10 mg/kg) or placebo every 2 weeks for 12 weeks. The primary endpoint was safety. The primary efficacy end point was the change from baseline in mean modified Mayo endoscopy subscore at week 12. Treatment with KHK4083 or placebo was continued every 4 weeks for up to 52 weeks in responders. Results: Long-term treatment with KHK4083 was well tolerated, with treatment-related adverse events being predominantly transient mild-to-moderate infusion-related reactions. Exploratory analysis of biopsy samples showed the virtually complete elimination of OX40+ cells in colon mucosa after 12 weeks of KHK4083 treatment. There were no significant differences between any of the randomized KHK4083 dose groups and placebo for the mean change in Mayo endoscopy subscore from baseline to week 12. Conclusions: KHK4083 can be safely administered intravenously at doses up to 10 mg/kg every 2 or 4 weeks for up to 52 weeks. Proof of pharmacodynamic action was confirmed by depletion of the elevated levels of the OX40+ cells associated with UC at all tested doses. Clinical response and mucosal healing (endoscopic improvement) in this population was not correlated with ablation of OX40+ T cells.

Corrigendum to: Randomized, Ascending Dose, Phase 2 Study of KHK4083, an Anti-OX40 Monoclonal Antibody, in Moderately Active Ulcerative Colitis.

[This corrects the article DOI: 10.1093/crocol/otaa049.].