Phase I Dose Escalation Trial Of Tremelimumab (Cp-675,206) Administered In Combination With Pf-3512676 In Patients With Melanoma Or Other Advanced Cancers

3046 Background: Tremelimumab, a fully human monoclonal antibody specific for cytotoxic T-lymphocyte antigen 4 (CTLA4), and PF-3512676, an oligodeoxynucleotide toll-like receptor 9 agonist, are both novel, targeted immune modulators that can elicit durable antitumor responses in patients with advanced cancer. The tolerability of the combination of these two agents was investigated. Methods: Eligibility criteria included advanced melanoma or other advanced cancer, ECOG performance status of 0 or 1, and no history of autoimmune disease. Patients received intravenous tremelimumab (6.0, 10.0, or 15.0 mg/kg) every 12 weeks plus 0.05 mg/kg subcutaneous PF-3512676 weekly. Further escalation of PF-3512676 (to 0.1 mg/kg and 0.2 mg/kg) was planned once the MTD of tremelimumab had been determined. Primary endpoint was safety of the treatment combination; secondary endpoints included clinical activity, pharmacokinetics (PK), and immunologic measurements. Results: To date, 15 patients (melanoma, n = 12; mesothelioma, n = 2; prostate, n = 1) have been treated in this study: 3 at dose level 1 (6 mg/kg tremelimumab + 0.05 mg/kg PF-3512676); 6 at dose level 2 (10 mg/kg tremelimumab + 0.05 mg/kg PF-351276); and 6 at dose level 3 (15 mg/kg tremelimumab + 0.05 mg/kg PF-3512676). There were two DLTs at dose level 3: G3 diarrhea (n=1) and G3 nausea and vomiting associated with biopsy-proven duodenitis (n=1). One DLT, G3 hypophysitis, occurred at dose level 2. Patients with DLTs responded to corticosteroid therapy. Common adverse events included mild to moderate PF-3512676 injection site reactions (n=14), mild to moderate flu-like symptoms (n=9), G1/2 diarrhea (n=9), and G1/2 nausea (n=8). Presently, there are 2 PRs (13%) and 5 SDs among the 15 patients. Updated safety, efficacy, and PK data will be reported. Conclusions: At dose levels tested to date, the combination of tremelimumab and PF-3512676 has been tolerable and showed evidence of antitumor activity in patients with advanced melanoma. The MTD for this combination has yet to be determined, and a fourth intermediate dose level (10 mg/kg tremelimumab + 0.1 mg/kg PF-3512676) is currently being explored. [Table: see text]