Phase I clinical trials of tezacitabine [(E)-2'-deoxy-2'-(fluoromethylene)cytidine] in patients with refractory solid tumors.
OBJECTIVE
To evaluate safety, tolerability, and pharmacokinetics of a new nucleoside analogue, tezacitabine [(E)-2'-deoxy-2'-(fluoromethylene)cytidine (FMdC)] in patients with refractory solid tumors.


METHODS
Seventy patients were enrolled in four separate Phase I trials. Patients had metastatic or relapsed cancer of the colon, breast, pancreas, gastrointestinal tract, lung, and other sites. FMdC was administered by i.v. infusion over 30 min in one of four dose schedules--from once every 3 weeks to twice a week for 3 weeks, with dose escalation in each. Maximum doses ranged from 630 to 16 mg/m(2).


RESULTS
Myelotoxicity, especially neutropenia, was the dominant toxicity and was generally dose-related. Grade 3 or 4 neutropenia occurred in 53% of patients but was of relatively short duration (1-8 days) in all of the patients. One patient experienced grade 3 thrombocytopenia and one patient grade 4 (duration 15 and 11 days, respectively). Transient febrile episodes were reported in 82% of patients with drug administration but were easily controlled. Drug-related gastrointestinal events were mild and appeared unrelated to dose. Pharmacokinetics were linear with dose, not appreciably affected by schedules, and not different after single or multiple doses. Terminal half-life was 3-4 h, and 23% of the administered drug was recovered in the urine as unchanged drug. The uridine analogue (FMdU), the deaminated metabolite of FMdC, was the primary metabolite. Objective antitumor activity was observed in eight patients: one exhibited a partial response and seven exhibited stable disease.


CONCLUSIONS
In general, FMdC was well tolerated. On the basis of the time to recovery from neutropenia, the recommended schedule for Phase II studies is one treatment every 2 weeks, at a minimum dose of 270 mg/m(2).
Rodriguez
Gladys I
GI
Cancer Therapy and Research Center, San Antonio, Texas 78207, USA. grodrigu@saci.org
Jones
Richard E
RE
Orenberg
Elaine K
EK
Stoltz
Maxine L
ML
Brooks
Donald J
DJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D003841:Deoxycytidine / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives / Q000493:pharmacokinetics / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D019008:Drug Resistance, Neoplasm; D005260:Female; D006207:Half-Life; D006801:Humans; D007239:Infections / Q000209:etiology; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D015394:Molecular Structure; D009362:Neoplasm Metastasis; D009364:Neoplasm Recurrence, Local / Q000188:drug therapy; D009369:Neoplasms / Q000188:drug therapy* / Q000401:mortality / Q000473:pathology; D009503:Neutropenia / Q000139:chemically induced; D013921:Thrombocytopenia / Q000139:chemically induced
D000964:Antimetabolites, Antineoplastic; D003841:Deoxycytidine; C086432:tezacitabine