A phase II study of ARQ 501 in patients with advanced squamous cell carcinoma of the head and neck

16509 Background: ARQ 501 is a DNA damage checkpoint pathway activator whose effect is to induce selective cell death in cancer cells, independent of the tumor cell's p53 status. Current evidence implicates a rapid and sustained increase of the pro-apoptotic protein E2F-1 by ARQ 501 as the mechanism of action. Cancer cells are selectively affected due to their pre-existing DNA damage. In initial clinical trials, there was evidence of activity in some patients with head and neck cancer and pre-clinical investigations also supported this application. Therefore, a phase 2 trial is warranted in this patient population. Methods: A phase 2 study in patients with locally advanced, recurrent or metastatic squamous cell carcinoma of the head and neck who had received up to 3 prior systemic therapies was initiated to assess overall response rate, progression free survival at six months, and to further characterize safety. Cycles consist of four weekly administrations of ARQ 501 at a dose of 450 mg/m2. Dose escalation is allowed if a patient successfully completed a full cycle of therapy and had no related grade 2 adverse events. Results: 59 patients have been enrolled to date and 47 have received at least one infusion of ARQ 501. Data is available for 34 patients (27M / 7F, median age, 57 years). Of the 47 patients treated, 11 patients did not reach a post baseline assessment (2 deaths, 8 PD prior to week 8 and 1 withdrew consent). Although at the current date, most patients have not reached their first tumor evaluation, 5 have been assessed for response per RECIST at eight weeks and one patient is demonstrating stable disease. The drug has been well tolerated with the most common adverse event being anemia (11% ) with corresponding edema, fatigue (both 5%), dyspnea (4%), and hyperbilirubinemia (2%). Conclusions: ARQ 501 is well tolerated in patients with advanced, recurrent or persistent squamous cell carcinoma of the head and neck. Enrollment is ongoing and further results will be presented. No significant financial relationships to disclose.