Phase II screening study of an LHRH analog, dexamethasone and somatostatin analog versus LHRH analogue with dexamethasone in HRPC

Abstract

15579 Background: As far as prostatic cancer is concerned, we know that somatuline (SMS) blocks GH, PRL, tissular growth factors (TGF) and that it has a direct antiproliferative cellular growth effect. The simultaneous administration of depot forms of SMS and LHRH analogues induced the greatest decrease in tumor growth. Methods: A randomised Phase II trial was carried out in M0 (PSA ≥ 20 ng/ml) and M1 patients with hormone refractory prostate cancer to simultaneously screen decapeptyl and dexamethasone, both with and without SMS (120 mg every 4 weeks), with respect to the PSA response rate, time to PSA progression, duration of survival and toxicity. Results: 72 patients with a median PSA of 77 ng/ml were randomised by 3 centers, 35 to decapeptyl, dexamethasone, both with and without SMS (DDS) and 37 to decapeptyl and dexamethasone (DD). 18 of 33 (54%) patients on DDS and 13 of 32 on DD (43%) had a PSA response (a decrease of at least 50% as compared to baseline). The median time to PSA was 5.5 months in the SMS group and 1.9 months in the group without SMS. At 6 months, 45.7% were PSA progression free in the SMS group versus 35.1% in the goup without SMS. The median time to PSA progression in PSA responders was 10.6 months in the SMS group and 13.9 months in the group without SMS. At 6 months, 73.7% of the PSA responders were progression free in the SMS group versus 81.3% in the group without SMS. 45 patients died (62.5%), 22 (62.9%) in the SMS group and 23 (62.2%) in the group without SMS. 15 and 19 of the deaths respectively were due to prostate cancer. The median duration of survival is 1.65 years in the SMS group and 1.48 years in the group without SMS. At 6 months, 85.7% were alive in the SMS group vs 78.1% in the group without SMS. At 12 months, 77.1% were alive in the SMS group vs 69.4% in the group without SMS. Conclusions: There is no evidence that SMS may have increased the incidence of side effects. The PSA response rate was slightly higher in the SMS group, 54% vs 43% and the median time to PSA progression in all patients appears to have been slightly longer in the SMS group. Fewer objective progressions were also observed in the SMS arm, 4 vs 12. These results suggest that SMS may add to the activity of decapeptyl and dexamethasone and thus have a role in the treatment of hormone refractory prostate cancer. No significant financial relationships to disclose.