A Phase I trial of the farnesyltransferase inhibitor L-778,123 and radiotherapy for locally advanced lung and head and neck cancer.

Purpose: Preclinical data have demonstrated that farnesyltransferaseinhibitors (FTIs) are radiation sensitizers in selected cell lines. The objective of this Phase I trial was to determine the maximally tolerated dose of the FTI L-778,123 in combination with radiotherapy in non-small cell lung cancer (NSCLC) and head and neck cancer (HNC). Experimental Design: L-778,123 was given by continuous i.v. infusion and dose escalated in conjunction with standard radiotherapy. The presence of a ras mutation was not required for study entry. Results: Nine patients (six NSCLC patients and three HNC patients) were enrolled on two dose levels of FTI. No dose-limiting toxicities were observed at the first dose level of 280 mg/m 2 /day during weeks 1, 2, 4, and 5 of radiotherapy. One episode of dose-limiting toxicity, grade IV neutropenia, was observed in one of three patients treated at 560 mg/m 2 /day during weeks 1, 2, 4, 5, and 7. No episodes of dose-limiting mucositis, esophagitis, or pneumonitis were observed. Of the four patients with NSCLC with evaluable disease, three patients had a complete response to treatment and one patient had a partial response. A complete clinical response to treatment was observed in two patients with HNC. In vitro studies in tumor cells obtained from a NSCLC patient on this trial showed radiosensitization with FTI and that tumor cells accumulated in G 2 -M after L-778,123 treatment. Conclusions: The combination of L-778,123 and radiotherapy at dose level 1 is associated with acceptable toxicity. Local responses have been observed in four NSCLC patients without a clear increase in radiotherapy-associated toxicities.