Raltitrexed (Tomudex) concomitant with radiotherapy as adjuvant treatment for patients with rectal cancer: preliminary results of phase I studies.

Radiotherapy, either alone or in combination with chemotherapy, may reduce local recurrence of rectal cancer following surgery and improve survival of patients with operable and advanced/recurrent/inoperable disease. Chemotherapy with 5-fluorouracil in combination with radiotherapy has been used both before and after surgery; however, the optimum schedule is unclear. In addition, alternative chemotherapy with raltitrexed (Tomudex) may be more convenient and better tolerated. The preliminary results of three phase I dose-finding studies are described, combining escalating doses of raltitrexed with radiotherapy as pre- or postoperative treatment for operable rectal cancer or as treatment for advanced/inoperable/recurrent rectal cancer. The recommended dose of raltitrexed when combined with adjuvant radiotherapy is likely to be 2.6 mg/m2. This is a small dose reduction compared with the dose of raltitrexed for the treatment of advanced colorectal cancer (3.0 mg/m2); however, toxicity appears to be lower using the pre-operative approach. Neo-adjuvant therapy with raltitrexed plus radiotherapy also demonstrated clinical activity in the pre-operative study, which showed that 22% of patients achieved a complete response and 56% a partial response. Once the recommended dose has been defined in each setting, large-scale studies will be undertaken as appropriate.