Phase I-II evaluation of cyclocytidine

Area of Science:

• Oncology
• Pharmacology

Background:

• Metastatic solid tumors and acute leukemia present significant treatment challenges.
• Cyclocytidine is an antineoplastic agent evaluated for its therapeutic potential.

Purpose of the Study:

• To evaluate the safety and efficacy of cyclocytidine in patients with advanced solid tumors and acute leukemia.

Main Methods:

• A Phase I-II clinical trial involving 102 patients with metastatic solid tumors or acute leukemia.
• Cyclocytidine was administered intravenously or subcutaneously in 5- or 10-day courses at doses ranging from 100-675 mg/m²/day.
• Patient response, duration of response, disease stabilization, and adverse events were meticulously recorded.

Main Results:

• Two complete and six partial responses were observed in evaluable solid tumor patients, particularly those with malignant melanoma or gastrointestinal adenocarcinoma.
• The median response duration was 6 months, with seven additional patients achieving disease stabilization for ≥2 months.
• No responses were noted in acute leukemia patients. Common side effects included nausea, vomiting, postural hypotension, and parotid pain at doses >200 mg/m²/day.
• Myelosuppression was absent at lower doses (100-200 mg/m²/day for 5 days) but increased with higher doses and longer durations, potentially linked to prior chemotherapy.

Conclusions:

• Cyclocytidine demonstrates activity against certain metastatic solid tumors, including melanoma and gastrointestinal cancers.
• The drug's efficacy in acute leukemia appears limited.
• Dose-dependent toxicities, including myelosuppression, necessitate careful administration, especially in patients with prior chemotherapy exposure.