Ligand Pharmaceuticals has exceeded its 600-patient enrollment goal in the second of two pivotal Phase III studies of Targretin (bexarotene) capsules in front-line combination therapy to treat advanced non-small cell lung cancer (NSCLC), the company announced.

The second randomized trial is known as SPIRIT II (Studies Providing Investigational Research in Targretin) and is being conducted at 165 sites worldwide, more than 80% of which are in North America. The study is designed to evaluate whether adding Targretin to front-line carboplatin/paclitaxel chemotherapy extends the lives of patients with advanced (stage IIIB with pleural effusion or stage IV) NSCLC. Ligand expects survival data from the study to be available in about one year. Targretin is currently approved to treat cutaneous T-cell lymphoma (CTCL).

"The SPIRIT studies of Targretin in non-small cell lung cancer are the largest Phase III clinical trials Ligand has ever conducted, and completing enrollment of both trials ahead of schedule represents an important milestone for the company," said Andres Negro-Vilar, Ligand's executive vice president and chief scientific officer. "The early completion of enrollment demonstrates growing interest among oncologists in applying Targretin's unique mechanism of action to the treatment of lung cancer."

Ligand's first Phase III study of Targretin in advanced NSCLC (called SPIRIT I) is an international trial being conducted at 94 sites worldwide, more than 70% of which are outside North America. SPIRIT I is examining Targretin in front-line combination therapy with a different chemotherapy regimen, cisplatin and vinorelbine. Patient enrollment in that study concluded in August, also ahead of schedule.

The primary endpoint of both Phase III studies is overall survival. The studies are powered to show approximately a 30% improvement in median survival among Targretin-treated patients compared to patients who receive combination chemotherapy only. The secondary endpoint is two-year survival.