Aims
An analysis of 177 pts from 3 phase I/II IPI studies conducted at NCI demonstrated 5-yr survival rates of 13-25%. In other phase II trials, IPI monotherapy was associated with long-term survival of 4+ yrs in some pts with MM. IPI in combination with DTIC in previously untreated MM patients significantly improved OS in phase III study CA184-024. Safety data from study 024 has been previously published. Here we report 4-yr survival data from study 024, the longest IPI survival follow-up from a phase III study.

Methods
Pts with treatment-naive MM were randomized to receive either IPI (10 mg/kg) + DTIC (850 mg/m2) or placebo + DTIC (850 mg/m2) given at Wks 1, 4, 7, 10 followed by DTIC q 3 wks through Wk 22. Pts with stable disease or better then received IPI or placebo q 12 wks as maintenance. This analysis reports OS with updated last known alive date or death date based on data collected through April 2012.

Results
Median OS for was 11.2 m [95% CI, 9.4-13.6] for IPI + DTIC (N=250) and 9.1 m [95% CI, 7.8-10.5] for placebo + DTIC (N=252). The 4-yr overall survival rates in the current analyses were 19.0% [95% CI, 14.2-24.2] for IPI + DTIC and 9.6% [95% CI, 6.1-13.5] for placebo + DTIC.

Conclusions
The 4-yr survival rates observed in an extended follow-up of a completed phase III trial suggests that IPI 10 mg/kg in combination with DTIC continues to demonstrate a survival benefit compared to the control arm. The continued survival of some patients at 4 yrs suggests that prolonged survival may indeed be obtained in some pts with treatment-naive MM. This observation of long-term survival benefit in a phase III RCT is consistent with observations from phase I/II studies of IPI in patients with advanced melanoma.