Background: Cisplatin (CDDP) is among the most active single agents against squamous cell carcinoma of the head and neck (SCCHN), and it is still the reference drug in the induction chemotherapy setting, when used in combination with infusional 5-fluorouracil (5-FU). Raltitrexed has been shown to be devoid of clinical activity against SCCHN when used alone; however, both preclinical and early clinical data regarding the combination raltitrexed-CDDP hold promise. Thymidylate synthase is the target enzyme of both raltitrexed and 5-FU; however, the two drugs have distinct sites of action on the enzyme and the combination of the two agents may be synergistic. We have previously shown that the combination of raltitrexed, levofolinic acid (LFA) and 5-FU has clinical activity against SCCHN; in a subsequent phase I study, cisplatin was added, and the combination of CDDP plus raltitrexed on day 1, followed by LFA and 5-FU on day 2, was judged feasible and active, since a 67% response rate was shown across all dose levels, with a 100% response rate at the recommended dose for phase II.
Methods: Patients with inoperable locally advanced or metastatic SCCHN, not pretreated with chemo- or radiotherapy were randomized to receive either CDDP 60 mg/m2 and raltitrexed 2.5 mg/m2 on day 1 and LFA 250 mg/m2 and 5-FU 900 mg/m2 on day 2 (arm A) or CDDP 65 mg/m2 and methotrexate 500 mg/m2 on day 1, and LFA 250 mg/m2 and 5-FU 800 mg/m2 on day 2 (arm B). Both treatments were repeated every 2 weeks. Evaluation for tumor response was performed after four cycles. According to Simon two-stage design, with a target complete response (CR) rate (p1) of 35%, at least 7 CR among the first 31 treated patients and 16 CR among the final sample size of 52 patients were required.
Results: An interim analysis was performed when 36 patients were evaluable in each arm. In arm A, 10 CR (28%) and 19 partial responses (PR) (53%) were observed, for an overall response rate of 81%. In arm B, 3 CR (8%) and 12 PR (34%) were observed, for an overall response rate of 42%. The difference in both CR and overall response rate between the two arms was statistically significant (p = 0.03 and <0.001, respectively). Therefore, the accrual was stopped in arm B and continued only in arm A. Overall, 13 CR (21%) and 34 PR (56%) were observed among the 61 patients who were accrued in arm A, for an overall response rate of 77% (95% confidence interval 64-87%). Neutropenia was the main side effect in both arms (grade 3-4 in 45 and 23 patients in arm A and B, respectively). Extrahematologic toxicity was mild in both arms; however, 2 patients in arm B died due to toxicity (grade 4 mucositis in one case, grade 4 renal toxicity in the other).
Conclusions: Although response data for our experimental treatment look encouraging, the hypothesis of a 35% activity, expressed as capability to induce a CR, cannot be accepted. The results obtained in this study are not substantially different from those of other trials of CDDP-5-FU-based regimens, and our combination is unlikely to represent a major breakthrough when used in this setting.
Copyright 2002 S. Karger AG, Basel