ObsEva Plunges 47%- But Gains After-Hours- On Uterine Fibroid Data

Shares in biopharma ObsEva SA (OBSV) plunged 47% in Monday’s trading despite the company announcing positive top-line results from the PRIMROSE 1 and 2 studies of Yselty (linzagolix) in women with heavy menstrual bleeding due to uterine fibroids (UF). The stock subsequently gained 7% in after-hours trading.

Indeed, PRIMROSE 1 met the primary endpoint at week 24, and showed that women receiving linzagolix experienced a statistically significant and clinically meaningful reduction in menstrual blood loss (≤80 mL and a ≥50% reduction from baseline) compared to placebo.

Women receiving 200 mg with ABT (1 mg estradiol and 0.5 mg norethindrone acetate daily) achieved a 75.5% (P<0.001) responder rate and those receiving 100 mg without ABT achieved a 56.4% (P=0.003) responder rate. 

The pooled week 24 data from these two Phase 3 studies showed a responder rate of 84.7% in women receiving linzagolix 200 mg with ABT, and 56.6% in women receiving linzagolix 100 mg without ABT.

In addition, PRIMROSE 2 demonstrated that continued treatment with linzagolix for 52 weeks provides sustained efficacy and is well tolerated. Responder rates of 91.6% and 53.2% were observed in women receiving 200 mg with ABT and 100 mg without ABT, respectively.

Across both studies, women receiving linzagolix experienced statistically significant improvements across a number of clinically relevant secondary endpoints, including reduction in pain, improvement in anemia and quality of life.

“We are extremely pleased by the overall performance of Yselty in addressing heavy menstrual bleeding, a major symptom of uterine fibroids. These data definitively confirm our belief that Yselty, with and without add-back therapy, has the potential to be an effective treatment for addressing the broad needs of women suffering from uterine fibroids,” said Dr. Ernest Loumaye, ObsEva CEO.

In PRIMROSE 1, the incidence of adverse events was similar between placebo and active treatment. The most frequently observed adverse events, with an incidence >5%, were headache and hot flushes. In addition, a minimal mean percentage change in lumbar spine bone mineral density (BMD) from baseline was observed in both treatment arms at week 24.

In PRIMROSE 2, the most frequently observed adverse events, with an incidence >5%, were headache, hot flushes and anemia. In addition, a small incremental change in BMD was observed at week 52 compared to week 24.

ObsEva is now preparing its regulatory submissions to the European Medicines Agency in 4Q 2020 and the U.S. Food and Drug Administration in 1H 2021.

“We understand that the investors are focused on the placebo-adjusted response rate observed in both PRIMROSE trials and minimized the importance of having a treatment for UF without having to add back estrogen to reduce bone loss” commented Wedbush analyst Liana Moussatos following the results.

She has a buy rating on the stock and $30 price target- indicating massive upside potential from the current share price of under $5.

“Of note, the Linzagolix 100 mg dose is the only oral GnRH dosing regimen being developed for UF without the need for ABT – a key differentiator. The Company’s analysis of CDC data suggests that hormonal ABT may be contraindicated in up to 50% of U.S. women with uterine fibroids, highlighting the urgent need for a low-dose GnRH antagonist that comes without add-back therapy” says Moussatos.

Net-net the analyst considers OBSV to be a buying opportunity right now due to transiently negative investor sentiment. Overall the stock has a cautiously optimistic Moderate Buy Street consensus with a $23.33 average analyst price target, indicating upside potential of over 600%. (See ObsEva stock analysis on TipRanks)

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