A single institution experience of EGFR inhibitors in patients with advanced squamous cell anal carcinomas (SCAC).

Abstract

623 Background: Although SCAC are relatively rare, their incidence has been increasing steadily. Because of limited data, treatment of metastatic disease is a major therapeutic challenge. Recent data has demonstrated a low rate of KRAS and EGFR mutations, suggesting a potential target of EGFR inhibitors. In this study, we report the safety and efficacy of EGFR inhibitors in patients (pts) with advanced SCAC. Methods: A retrospective analysis was conducted using the Moffitt Cancer tumor registry from 1/2009 to 1/2014. Eligible pts had advanced SCAC and received an EGFR inhibitor as part of their treatment. Results: 13 pts were identified for analysis. Median age was 59 years (range: 41-68). All pts received concurrent chemoradiation (Nigro regimen) as initial treatment and subsequently had recurrence. Upon diagnosis of recurrent disease, 5 pts received 2 lines of systemic chemotherapy, 5 pts received 1 line and 3 did not receive any treatment prior to receiving EGFR inhibitors. 5 pts received single agent cetuximab (4) or panitumumab (1) and the others received cetuximab or panitumumab with irinotecan or FOLFIRI. Pts received a median EGFR inhibitor dose of 8 (range: 2-45). Objective response rates were 30.8% (1 CR, 3 PR) and disease control rates were 46.2%. 1 pt with CR was on single agent cetuximab as second line therapy and 3 pts with PR were on cetuximab plus chemotherapy as front-line. With a median follow-up of 9.6 months (mo), the median PFS and median OS were 4.4 mo (95% confidence interval (CI) 2.99-5.81) and 11.4 mo (95% CI 7.93-14.87), respectively. No KRAS mutation was detected in 8 pts and KRAS testing was not done on 5 other pts. Grade 3 toxicities included anemia (n = 2), fatigue (n = 1), depression (n = 1), dyspnea (n = 1), anorexia (n = 1), nausea (n = 1) and diarrhea (n = 1). No grade 4 toxicities were observed. Conclusions: Our analysis suggests that EFGF inhibitors have potential efficacy and are reasonably well tolerated in patients with SCAC. These findings warrant further evaluation in a large prospective trial.