Single-agent pulse dactinomycin has only modest activity for methotrexate-resistant gestational trophoblastic...

To determine the effectiveness of single-agent pulse dactinomycin for methotrexate-resistant low-risk gestational trophoblastic neoplasia (GTN).

Ten patients with low-risk GTN (WHO/FIGO score <8) previously treated with uterine evacuation and single-agent methotrexate were treated with pulse dactinomycin 1.25 mg/m(2) every 2 weeks.

Patients had antecedent pregnancies of complete mole (7), partial mole (1), missed abortion (1), and choriocarcinoma (1). One patient underwent hysterectomy during methotrexate treatment. The mean hCG level and WHO score before dactinomycin was 1476 and 4.1, respectively. Six of 10 (60%) patients achieved complete remission with single-agent pulse dactinomycin. Two others responded to a 5-day regimen of dactinomycin, 1 responded to a multidrug regimen, and 1 had chemo-resistant disease dying of metastatic choriocarcinoma. After median follow-up of 11.9 months, 9 of 10 patients remain without relapse. A mean of 3.3 (1-6) cycles were given-4.5 (3-6) for responders and 1.5 (1-2) for nonresponders. In 33 cycles of chemotherapy administered, there were 46 toxicity events: all events were graded as 1. While WHO scores were comparable between responders and nonresponders (mean 3.8 vs. 4.5), hCG levels were lower in responders (mean 37 vs. 3634) but the sample size was too small to reach statistical significance.

Although remission rates of 80-90% have been reported for pulse dactinomycin, patients with methotrexate-resistant GTN had only a 60% remission rate. Prediction of remission may be more closely associated with hCG levels than with WHO score alone.