703 POSTER A phase I and pharmacokinetic (PK) study of BIBW 2992, an oral irreversible dual EGFR/HER2 inhibitor

A phase II study of afatinib (BIBW 2992), an irreversible ErbB family blocker, in patients with HER2-positive metastatic breast cancer progressing after trastuzumab

Afatinib is an oral, ErbB family blocker, which covalently binds and irreversibly blocks all kinase-competent ErbB family members. This phase II, open-label, single-arm study explored afatinib activity in human epidermal growth factor receptor 2 (HER2)-positive breast cancer patients progressing after trastuzumab treatment. Patients had stage IIIB/IV HER2-positive metastatic breast cancer, with progression following trastuzumab or trastuzumab intolerance and an Eastern Cooperative Oncology Group (ECOG) performance status of 0–2. Patients received 50 mg afatinib once-daily until disease progression. Primary endpoint was objective response rate (Response Evaluation Criteria in Solid Tumors 1.0), with tumor assessments every 8 weeks. Forty-one patients were treated. Patients had received a median of three prior chemotherapy lines (range, 0–15) and 68.3% had received trastuzumab for >1 year. Four patients (10% of 41 treated; 11% of evaluable patients) had partial response. Fifteen patients (37% of 41) had stable disease as best response and 19 (46% of 41) achieved clinical benefit. Median progression-free survival was 15.1 weeks (95% confidence interval [CI]: 8.1–16.7); median overall survival was 61.0 weeks (95% CI: 56.7–not evaluable). Most frequent common terminology criteria for adverse events grade 3 treatment-related adverse events were diarrhea (24.4%) and rash (9.8%). Afatinib monotherapy was associated with promising clinical activity in extensively pretreated HER2-positive breast cancer patients who had progressed following trastuzumab treatment.

Phase I study of continuous afatinib (BIBW 2992) in patients with advanced non-small cell lung cancer after prior chemotherapy/erlotinib/gefitinib (LUX-Lung 4)

PURPOSE

This Phase I study determined the maximum-tolerated dose (MTD) of afatinib (Afatinib is an investigational compound and its safety and efficacy have not yet been established) (BIBW 2992; trade name not yet approved by FDA), an irreversible inhibitor of epidermal growth factor receptor (EGFR)/human epidermal growth factor receptor (HER)1 and 2, up to a dose of 50 mg/day in advanced non-small cell lung cancer (NSCLC), to establish the recommended dose for Phase II.

METHODS

Patients with advanced NSCLC who had received prior platinum-doublet chemotherapy and/or erlotinib/gefitinib therapy, or who were ineligible for, or not amenable to, treatment with established therapies, received oral afatinib once daily. The MTD was determined based on dose-limiting toxicities (DLTs); other assessments included safety, pharmacokinetic profile, antitumour activity according to response evaluation criteria in solid tumours and EGFR/HER1 mutation analysis where possible.

RESULTS

Twelve evaluable patients were treated at doses of 20-50 mg/day. One DLT was observed at 50 mg/day in Course 1 (Grade 3 mucositis). The most frequent drug-related adverse events were diarrhoea, dry skin, stomatitis, rash, paronychia and anorexia; most were Grade 1 or 2. Six out of 12 patients had tumour size reductions; durable stable disease was achieved in three patients including one with EGFR/HER1 exon 19 and T790 M mutations. Peak plasma concentrations of afatinib were reached 3-4 h after administration and declined with a half-life of 30-40 h. Afatinib 50 mg/day was well tolerated with an acceptable safety profile during Phase I.

CONCLUSION

Recommended dose for Phase II was defined as 50 mg/day for Japanese patients; the same as for non-Japanese patients.