Strontium 89 Combined with Gemcitabine in Androgen-Resistant Prostate Cancer: Results of a Phase I-II Study

ABSTRACT

Background: Strontium 89 (Sr89), a beta-emitter particle that precipitates in bone, has a palliative role in the treatment of painful bony metastases in androgen-resistant prostate cancer (ARPC) patients. Questionable additional benefit has been reported when it was combined with chemotherapy.

Aim: To evaluate the efficacy of Sr89 given in combination with gemcitabine in ARPC patients with painful bony metastases.

Methods: Gemcitabine was given at a loading dose of 1000 mg/m2 on day 1. A single dose of strontium-89 (4mCi) was administered on day 8. On day 29, gemcitabine at a dose of 100 (dose level 1), 200 (dose level 2) and 400 (dose level 3) mg/m2 was delivered for once weekly for 7 weeks. The evaluated parameters included (a) PSA levels, (b) pain relief and change in ECOG performance status, and (c) bone scan findings.

Results: Nine patients were entered into this study. Four patients each completed dose levels 1 and 2. One patient received dose level 3. Seven (78%) patients achieved an improvement in their bone scan findings (complete response in one patient, improvement in two, and stable disease in four) that led to pain relief and an improvement in quality of life. PSA decreased (>50%) in four (44%) patients and <50% in one patient. Median survival was 19.4 months. One patient on dose level 3, who had coronary artery disease, developed chest pain that required hospitalization. No further therapy on dose level 3 was given. No grades 3 or 4 side effects occurred in patients on dose levels 1 or 2.

Conclusions: The combination of Sr89 and gemcitabine was well tolerated at the doses of 4 mCi and 200 mg/m2 (dose level 2), respectively. The treatment was associated with improvement in bone scan findings, improved quality of life and a decrease of PSA. Further studies investigating this regimen are warranted.