Erlotinib demonstrated an improvement in clinical benefit. Future directions should include evaluating its use in less advanced prostate cancer.

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15569 Background: The human epidermal growth factor receptor (HER1/EGFR) is known to be over expressed in a variety of cancers, including prostate cancer. Erlotinib is an orally active small molecule tyrosine kinase inhibitor (TKI) targeted against HER1/EGFR (ErbB1). Methods: Pts with advanced or metastatic prostate cancer, adequate organ function and Karnofsky performance status (KPS) ≥ 50% were enrolled in a phase II single institution study. Pts were required to have documented PSA progression before study entry. The primary objective was to determine the efficacy of erlotinib defined as a decrease or stabilization of PSA. Pts received erlotinib 150 mg/day; if no acceptable toxicity was reported in the first 3 weeks, the dose was increased to 200 mg at week 4, and continued until disease progression or unacceptable toxicity. Results: Thirty patients were treated between April 2004 and February 2006, Median age was 69 years (range 51–77) median KPS was 80 (70–100). Median PAL was 85 UI/L (range 33–732), median LDH 224 UI/L (144–1,016) and PSA 102 ng/ml (3, 4–1213). Twenty-eight pts had metastatic disease, 2 had PSA relapse only and 29 were androgeno-independant. Twenty three had received prior chemotherapy (median 2 lines, range (1–7)). Dose escalation was possible in 16 (55%) pts and median duration of treatment was 60 days (14–99). The most common grade 3 toxicities were fatigue (3 ), anaemia (2), diarrhea (2) vomiting (2) cutaneous toxicity (1); one pt. had grade 4 anemia. Median PFS was 29 days (IC 95 [28–33]), median OS 17,38 months. PSA stabilization was observed in 4 pts; no pt had a decrease in PSA. Clinical benefit evaluation based on KPS and pain was achieved in 8 of 20 evaluable pts (40%). Conclusion: Erlotinib demonstrated some activity in advanced prostate cancer with 14% of pts achieving PSA stabilization and 40% a clinical benefit. Erlotinib was well tolerated. Future directions might include evaluating its use in less advanced disease and in pts with EGFR kinase domain mutations. Understanding which biomarkers predict response to erlotinib will likely be important in its application in the metastatic setting. No significant financial relationships to disclose.