A phase I clinical and pharmacokinetic study of flavopiridol administered concurrently with 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX) for advanced solid tumors

13515 Background: Flavopiridol, a potent cyclin-dependent kinase inhibitor, enhances oxaliplatin-induced apoptosis in HCT116 colon cancer cells in vitro, especially with concurrent therapy. Significant tumor regressions were also observed in HCT116 xenografts treated with flavopiridol and oxaliplatin therapy versus either therapy alone. Methods: Therefore, an ongoing phase I trial in advanced solid tumors was designed in which flavopiridol at a fixed dose (40 mg/m2 over 1 hour) was administered concurrently with escalating doses of oxaliplatin (60 mg/m2 -> 80 mg/m2 over 2 hours), given as part of a modified FOLFOX6 regimen at standard doses every 14 days. Patients then received escalating doses of infusional 5-fluorouracil over 48 hours (900 mg/m2/day -> 1200 mg/m2/day). Standard phase I eligibility criteria apply. Prior FOLFOX or oxaliplatin was allowed. Results: Median characteristics of nineteen evaluable patients: age 54 (39–77), KPS 80% (70–90), 9 males/10 females, 3 prior regimens (range 1 to 10). The combination has been well-tolerated, with 1 dose limiting toxicity occurring with oxaliplatin at 85 mg/m2 and infusional 5-fluorouracil at 1200 mg/m2/day (grade 3 hyponatremia and grade 3 syncope). Pharmacokinetic studies for flavopiridol indicate no appreciable difference in Cmax despite escalation of oxaliplatin dose. We have observed 1 partial response to treatment in pancreatic cancer. Stable disease has been seen in 5 patients, including 1 breast cancer (3 months), 1 gastric cancer (2 months), 1 anal cancer (7 months) and 2 colorectal cancers (5+ months), with one patient previously treated with oxaliplatin. Conclusions: The combination of flavopiridol and modified FOLFOX6 can be given safely without a significant increase in toxicity. The pharmacokinetic data for flavopiridol remains unchanged despite escalating doses of oxaliplatin. Activity has been observed in several tumor types, with promising activity noted for colorectal cancers even with prior oxaliplatin chemotherapy. Therefore, further dose escalation of flavopiridol is currently planned. No significant financial relationships to disclose.