Evaluation of intravenous 6-thioguanine as first-line chemotherapy in women with metastatic breast cancer

James N. Ingle, Donald I. Twito, Vera J. Suman, James E. Krook, James A. Mailliard, Harold E. Windschitl, Robert F. Marschke

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


6-Thioguanine (6-TG) is a purine analog that has marked variability in plasma concentration after oral administration. Following the development of a multiple-day i.v. regimen, we performed a phase II trial of this agent as first-line chemotherapy in women with metastatic breast cancer. Forty-one patients with measurable (31 patients) or evaluable (10 patients) disease were entered into this trial. 6-TG was administered i.v. over a 10 min period daily for 5 consecutive days, with a planned cycle length of 35 days. The daily dosage level was 55 mg/m2 in the first 15 patients, but this was increased to 65 mg/m2 in the remaining patients due to inadequate myelosuppression at the lower dose. Six patients, all with measurable disease, achieved a complete response (CR) (two patients) or a partial response (PR) (four patients). Three responses occurred at the 55 mg/m2 level and three at the 65 mg/m2 level. The 95% confidence interval (CI) for the true response rate among patients with measurable disease was 6-39%. The median time to progression was 140 days and median survival time was 460 days. The regimen was well tolerated. We conclude that 6-TG, as given in this study, has limited activity as first-line chemotherapy for women with metastatic breast cancer.

Original languageEnglish (US)
Pages (from-to)69-72
Number of pages4
JournalAmerican Journal of Clinical Oncology: Cancer Clinical Trials
Issue number1
StatePublished - Feb 1997


  • 6-Thioguanine
  • Chemotherapy
  • Metastatic breast cancer
  • Phase II clinical trial

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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