Phase II trial of 9-beta-D-arabinofuranosyl-2-fluoroadenine 5'-monophosphate in non-Hodgkin's lymphoma: prospective comparison of response with deoxycytidine kinase activity.

A phase II study of 9-beta-D-arabinofuranosyl-2-fluoroadenine 5'-monophosphate was done in non-Hodgkin's lymphoma with a loading dose/continuous intravenous infusion schedule, consisting of a 20 mg/m2 loading dose followed by a continuous i.v. infusion of 30 mg/m2/24 h for 48 h. The loading dose was held constant while the continuous i.v. dose was escalated or decreased as appropriate for toxicity. Twenty-six patients were entered on the study; 25 are evaluable for response. The patients' median age was 61 years (range 25 to 73); their mean performance status was 1.1. They had received a mean of 2.6 prior chemotherapeutic regimens, and six also had prior radiation therapy. There was one complete response lasting 9+ months, and there were seven partial responses lasting 20, 13, 11, 11, 10, 5, and 2 months (response rate 32%). Toxicity was acceptable and consisted mainly of myelosuppression. 9-beta-D-arabinofuranosyl-2-fluoroadenine 5'-monophosphate is dephosphorylated in vivo and then is thought to be activated intracellularly to 9-beta-D-arabinofuranosyl-2-fluoroadenine 5'-triphosphate. The rate-limiting enzyme is deoxycytidine kinase. Deoxycytidine kinase activity was determined on pretreatment tumor samples for correlation with response. There was no difference between the values for responders and nonresponders. There was a trend for higher values in more malignant histological subtypes.