Phase II study of erlotinib in metastatic or unresectable malignant peripheral nerve sheath tumors (MPNST)

Abstract

9518 Background: MPNSTs are rare soft tissue tumors (STS) that are relatively resistant to chemotherapy. 26% have epidermal growth factor receptor (EGFR) amplification. In preclinical studies, NF1/p53 murine MPNSTs in vitro are stimulated by EGF and inhibited by EGFR inhibitors. We proposed to assess response rate (RR) to erlotinib in adult patients with unresectable or metastatic MPNST. Methods: Patients (pts) were required to have measurable disease, Zubrod performance status (PS) <3, adequate organ function, no prior EGFR therapy, and centrally reviewed confirmation of diagnosis. Treatment was erlotinib 150 mg by mouth daily, in continuous 28 day cycles. Disease evaluation was performed every 2 cycles. Results: 24 pts enrolled in 22 months, from 13 institutions. 20 pts were deemed eligible. Median age was 45.3 years; 50% had neurofibromatosis. At enrollment, 15 had a PS of 0–1, 18 had metastatic disease, and 19 had unresectable disease. Pts were heavily pretreated: 9 pts had ≥ 2 prior regimens, 6 pts had 1 prior regimen, and 4 pts had no prior chemotherapy (1 unknown). 19 of 20 pts were assessable for toxicity: 6 pts had grade 3 toxicities; only 1 was hematologic (anemia). Mild rash (in 15 pts) and fatigue (in 8 pts) were the most common side effects. 20 pts were evaluable for response: 1 had stable disease after first evaluation and 19 had no response. Median progression-free survival was 2 months. 14 patients have died; median overall survival was 4 months. Because no objective responses were observed in the first stage of the study, it was closed to further accrual. Conclusions: We were able to accrue pts with a rare STS to a phase II histology specific study through a single adult cooperative group. In spite of preclinical promise of EGFR inhibition, erlotinib does not appear to be active in MPNSTs. To further understand the role of EGFR in MPNST, we are assessing EGFR expression immunohistochemically and performing quantitative PCR for genes altered by EGFR stimulation/inhibition on pt tumors. No significant financial relationships to disclose.