Double-blind randomized study of lonidamine and radiotherapy in head and neck cancer

Preclinical studies showed lonidamine to potentiate the effects of x-irradiation by inhibiting the repair of potentially lethal damage. This Phase III double blind, placebo-controlled study was performed to evaluate whether lonidamine can increase the tumor control of radiotherapy in the treatment of advanced head and neck cancer without any synergistic toxic effects on the exposed normal tissues.

Ninety-seven patients with Stages II-IV squamous cell carcinoma of the head and neck were enrolled. Separate analyses were done on the 96 eligible patients and the 90 patients who completed the prescribed treatment regimen. Patients received radiotherapy up to a planned total of 60-66 Gy, in 2 daily fractions of 1.5 Gy each and either lonidamine (450 mg p.o. in three divided daily doses) or placebo, given continuously for 3 months or up to 1 month after the end of radiotherapy.

The rate of tumor clearance was 66% (32/48) in the lonidamine group and 65% (31/48) in the placebo group, while the subsequent failure rate was 50% and 77%, respectively (p < 0.05). The 3 and 5 year locoregional control rates in the adequately treated patients achieving complete tumor clearance were 66% and 63% for lonidamine vs. 41% and 37% for placebo. The disease-free survival in adequately treated patients was significantly better in the lonidamine group (p < 0.03), with 3 and 5 year rates of 44% and 40%, respectively, vs. 23% and 19% in the placebo group. The overall survival rate for all eligible patients at both 3 and 5 years was 44% in the lonidamine group and 44% and 31%, respectively, in the placebo group. Both acute and late radiation reactions were similar in the two groups. Myalgia and testicular pain were the most frequent side effects of lonidamine with an incidence of 8.5% and 4.2%, respectively.

The addition of lonidamine to hyperfractionated radiotherapy was correlated with a statistically and clinically significant proportion of long-term disease-free patients. The toxicity of radiotherapy was not aggravated by the drug and the overall tolerance of the combined regimen was acceptable.