Raltitrexed plus radiotherapy for the treatment of unresectable/recurrent rectal cancer: a phase I study

Raltitrexed and Radiotherapy as Adjuvant Treatment for Stage II-III Rectal Cancer: A Feasibility Study

Aims and Background

Adjuvant 5-FU chemotherapy plus radiotherapy represents the standard treatment for radically resected rectal cancer at high risk of relapse according to the NIH Consensus Conference. The therapeutic gain was obtained with a high rate of severe treatment-related toxicity and a sub-optimal patient compliance with this regimen. Raltitrexed is a specific thymidylate synthase inhibitor with a convenient administration schedule, acceptable toxicity and radiosensitizing properties, as the published phase I trials in combination with radiotherapy have shown. The aim of this prospective multicenter phase II study was to evaluate the feasibility, gastrointestinal and hematological acute toxicity of raltitrexed in combination with radiotherapy in rectal cancer patients.

Methods

From September 2000 to June 2004, 50 patients with radically resected stage II-III rectal adenocarcinoma were treated. All patients were evaluable for compliance and acute toxicity. Within 45-60 days of surgery, each patient underwent concomitant adjuvant radiochemotherapy. Radiotherapy was administered to the pelvis (plus perineum after abdominoperineal resection) with photon beam energy exceeding 5 MV, 3-4 fields, 45 Gy/25 fractions/5 weeks plus a boost delivered to the site of resected disease with 3-4 fields, 9 Gy/5 fractions/1 week to a total dose of 54 Gy. The boost dose was administered after complete exclusion of the small bowel from the treatment volumes; if this was not possible a total dose of 50.4 Gy was given. Raltitrexed was administered intravenously at a dose of 3 mg/m2 as a bolus injection on days 1 and 22 of radiotherapy one hour before treatment, for a total of two cycles. Each patient underwent weekly clinical evaluation and laboratory tests. Toxicity was assessed by the WHO scale.

Results

Forty-five (90%) patients completed the established treatment. Acute severe toxicity included grade III proctitis in 4/50 (8%), grade III-IV diarrhea in 4/50 (8%), grade III perineal dermatitis in 4/50 (8%) and grade III leukopenia in 2/50 (4%) patients; five patients (10%) experienced a transient grade III increase in their liver biochemistry values.

Conclusions

Our data related to acute toxicity and patient compliance proved the feasibility of this adjuvant radiochemotherapy treatment. A longer follow-up is necessary to evaluate the effectiveness of this new regimen in terms of disease-free and overall survival.

Phase I study of concomitant chemoradiation with raltitrexed in locally advanced head and neck cancer

In patients with non-resectable head and neck cancer concomitant chemoradiotherapy is increasingly used, especially in cases of oropharyngeal and hypopharyngeal tumours. Most chemoradiotherapy regimes contain cisplatin as a single agent or in combination with fluorouracil. However, not all patients are fit enough for a cisplatin-containing regime or they refuse hospital admission. Raltitrexed is a specific thymidylate synthase inhibitor that has been studied as a radiosensitiser in rectal cancer. Raltitrexed can be administered easily in an outpatient setting and has few short-term effects. We studied raltitrexed at escalating doses combined with standard radiotherapy in advanced head and neck cancer patients. Seventeen patients with locally advanced head and neck cancers were enrolled in the study. Raltitrexed was administered at dose levels of 1.5, 2.0, 2.5 and 3.0 mg/m(2) intravenously (i.v), once every 3 weeks, for two doses. Radiotherapy consisted of 70 Gy given over 7 weeks in five fractions of 2 Gy per week. In general, treatment toxicity (DLT), complicated febrile neutropenia, was observed at 3.0 mg/m(2) in two of four patients. The dose of 2.5 mg/m(2) was extended thereafter with additional patients without major toxicity. Radiotherapy had to be interrupted in one patient. Five patients had a clinical complete response(CR) and eleven a partial response (PR) six weeks after the last fraction of radiotherapy. Twelve out of 17 patients remained free of locoregional recurrence after a median follow-up of 24(+) months (range 3-60+ months). Raltitrexed, at a dose of 2.5 mg/m(2) given twice 3 weeks apart, can be administered in combination with 70 Gy of radiotherapy in locally advanced head and neck cancer patients with a manageable tolerability profile. The clinical results and convenience of the schedule make raltitrexed an attractive drug to explore further in patients considered unfit for cisplatin-containing chemoradiation regimens.

Combined-Modality Therapy of Rectal Cancer with Oxaliplatin-Based Regimens

There are 2 conventional treatments for clinically resectable rectal cancer. First is surgery and, if the tumor is stage T3 and/or N1/2, this is followed by postoperative combined modality therapy. The second is preoperative combined modality therapy followed by surgery and postoperative combined modality therapy if the tumor is stage uT3/4 and/or node-positive. There are a number of new chemotherapeutic agents that have been developed for the treatment of patients with colorectal cancer. Phase I/II trials examining the use of these new chemotherapeutic agents in combination with pelvic radiation therapy, most commonly in the preoperative setting are in progress and suggest higher complete response rates. There is considerable interest in integrating oxaliplatin into preoperative combined modality therapy regimens for rectal cancer. Based on results from phase I/II trials, the recommended regimen for patients who receive oxaliplatin-based combined modality therapy is continuous infusion 5-fluorouracil or capecitabine with pelvic radiation.