Randomized Phase 2/3 Trial of CpG Oligodeoxynucleotide PF-3512676 Alone or With Dacarbazine for Patients With Unresectable Stage III and IV Melanoma

BACKGROUND: The primary objective of this phase 2 study was to assess the objective response rate (complete response [CR] þ partial responses [PR]), by Response Evaluation Criteria in Solid Tumors, of PF3512676, a CpG oligodeoxynucleotide, alone in 2 doses or in combination with dacarbazine (DTIC) in patients with unresectable stage IIIB/C or stage IV malignant melanoma, with the aim of selecting an arm to take forward to a phase 3 portion of the study. METHODS: A total of 184 patients were randomized to 1 of 4 treatments: PF-3512676 10 mg (low dose), at 40 mg (high dose), 40 mg plus DTIC (850 mg/m 2 ), or DTIC (850 mg/m 2 ) alone. Patients received PF-3512676 subcutaneously weekly in a 3-week cycle and received DTIC intravenously on the first week of the cycle. RESULTS: The objective response rate (PR or CR, confirmed or unconfirmed) in the 40 mg þ DTIC arm was 16% (7 patients) compared with 8% (3 patients) with DTIC alone. One (2%) patient in the 10-mg and 0 patients in the 40-mg arms achieved an objective response. Best response of CR or PR or stable disease (SD), with no minimum duration defined for SD, was achieved by 15 (33%) patients in the 40 mg þ DTIC arm, 15 (38%) patients in the DTIC-only arm, 8 (17%) patients in the 10-mg arm, and 9 (20%) patients in the 40-mg arm. The most frequently reported adverse events were classified as local injection site reactions or systemic flu-like symptoms, specifically fatigue, rigors, and pyrexia. CONCLUSIONS: PF-3512676 at the doses used was generally well tolerated. The modest objective response rates observed in all arms did not warrant continuation to the phase 3 portion of the study. Cancer 2009;115:3944–54. V C 2009 American Cancer Society.