Myovant now has two phase 3 trials supporting its relugolix candidate for uterine fibroids, setting up a regulatory filing in the US before the end of the year.
The company, part of the Swiss Roivant group headed by Vivek Ramaswamy, says the LIBERTY 2 trial showed a 71.2% response rate for once-daily relugolix in women with uterine fibroids and heavy menstrual bleeding, in line with the outcome of its LIBERTY 1 trial reported in May.
Women saw an average 84% reduction in menstrual blood loss when GnRH antagonist relugolix was added to hormonal therapy with oestradiol and norethindrone acetate, as well as a significant drop in pain, said the biotech.
There was also a low incidence of side effects such as hot flushes and what appeared to be little impact on bone mineral density, which can drop with hormonal therapies for uterine fibroids.
The results are a close match to the first phase 3 trial, setting up what should be a smooth path through regulatory review, but Myovant’s shares didn’t depart from an inexorable downwards creep in the last few months.
Why? Because the jury is still out on whether Myovant can compete in the marketplace with AbbVie and its rival drug elagolix, which has already been approved as Orilissa for endometriosis and was due to be filed for the uterine fibroids indication right about now, giving it a few months’ head start.
Myovant is banking on the convenience of once-daily dosing with relugolix, and hopes this will make it more popular among patients than twice-daily elagolix.
It reported additional data this week, which backed the bioequivalence of a new formulation – that includes relugolix and the two hormonal drugs in a single tablet – to the drugs given in two separate tablets in the LIBERTY trials programme. That single-tablet version will be taken forward into a regulatory filing.
There are also questions about the willingness of women to add either of the new drugs to their existing therapies because of the risk of additional side effects like hot flushes and bone mineral density reductions, although both Myovant and AbbVie insist the additional risk is modest.
Uterine fibroids are non-cancerous tumours that form in the muscle walls of the uterus and affect between 20% and 80% of women by the age of 50. In many cases they cause no symptoms, but around a quarter of women experience pain, abnormal bleeding and other symptoms, and may experience fertility problems.
“Millions of women suffer from heavy bleeding, pain, anaemia, lost productivity, or pregnancy complications resulting from uterine fibroids,” said Andrea Lukes, founder of the Carolina Women’s Research and Wellness Center and a member of the LIBERTY trials steering committee.
“The data from the two pivotal LIBERTY studies suggest we have a medicine that could offer meaningful improvement in symptoms without sacrificing safety and tolerability.”
Analysts suggest that uterine fibroids could be a $1bn-plus market for GnRH antagonists. The big question is whether AbbVie’s marketing muscle or Myovant’s more patient-friendly dosing will win out in the jostle for market share.