Novartis announced that the Phase 3 RELAX-AHF study has shown that investigational RLX030 (serelaxin) improved symptoms and reduced deaths by one-third at the end of six months in patients with acute heart failure (AHF); most of these deaths were due to cardiovascular causes. RLX030 is a recombinant form of the human hormone relaxin-2 which occurs naturally in both men and women; RLX030 is believed to act through multiple mechanisms on the heart, kidneys and blood vessels.

RELAX-AHF was an international randomized, double-blind study involving 1,161 patients and was designed to compare the efficacy and safety profile of RLX030 to placebo in addition to standard therapy for the treatment of AHF. RLX030 was given upon hospitalization in the form of an intravenous infusion (30mcg/kg/day) for 48 hours in addition to conventional therapy for AHF, ie, loop diuretics and other medicines.

The study had two primary endpoints using different scales to measure reduction in dyspnea. The visual analog scale (VAS) showed a significant benefit up to Day Five (P=0.0075), whereas the Likert scale (a baseline-related short-term assessment of dyspnea relief) did not reach significance at 6, 12 and 24 hours (P=0.702). As one of the primary endpoints was met the study was positive according to protocol criteria. The study did not meet its secondary efficacy endpoints, namely days alive and out of hospital up to Day 60 (P=0.37), and cardiovascular death or re-hospitalization due to heart or kidney failure up to Day 60 (P=0.89).

Results showed that 7.3% of patients died from all causes in the RLX030 group compared to 11.3% in the placebo group (P=0.02) at 180 days of follow-up. All-cause mortality up to Day 180 was a safety endpoint of the study. The number of deaths due to cardiovascular causes to Day 180 (an additional pre-specified efficacy endpoint) was also significantly lower with RLX030 than placebo (6.1% vs. 9.6%, P=0.028). RLX030 was therefore associated with a 37% reduction in all-cause and cardiovascular mortality at the end of six months.

In addition to its effects on mortality and symptoms, RLX030 met several other efficacy endpoints including significantly reducing the worsening signs and symptoms of heart failure up to Day 14 (P=0.024), thereby decreasing the need for intensified heart failure treatment. RLX030 also reduced the mean length of stay in hospital by 0.9 days (P=0.039) and in the intensive/cardiac care unit by 0.4 days (P=0.029).

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