-PROLONG data demonstrating ebopiprant was well tolerated and showed 
early evidence of efficacy selected for presentation- 
 
   - Phase 2b/3 adaptive dose-ranging study planned to initiate in Q4:21- 
 
 
 
   GENEVA, Switzerland and BOSTON, MA -- June 10, 2021 -- ObsEva SA 
(NASDAQ: OBSV) (SIX: OBSN), a biopharmaceutical company developing and 
commercializing novel therapies to improve women's reproductive health, 
today announced the presentation of clinical data from the PROLONG Phase 
2a proof-of-concept study of ebopiprant for the treatment of spontaneous 
preterm labor at the Royal College of Obstetricians and Gynecologists 
(RCOG) Virtual World Congress 2021. As previously disclosed, the PROLONG 
data demonstrated that ebopiprant was well tolerated and showed early 
evidence of efficacy in pregnant women with spontaneous preterm labor 
and supports the advancement into a Phase 2b/3 adaptive study. 
 
   "We are encouraged by the positive data generated to date, highlighting 
the unique mechanism of action and the potential clinical benefit of 
ebopiprant for the treatment of preterm labor to reduce the incidence of 
preterm birth," said Ben Mol, Ph.D., M.D., Professor of Obstetrics and 
Gynaecology, Monash Medical Centre, Melbourne Australia and a leading 
Key Opinion Leader in preterm labor therapeutics. "A key objective in 
the treatment of preterm labor is to delay delivery for at least 48 
hours, as this allows for the transfer of women to centers with neonatal 
intensive care facilities and for the peak effect of corticosteroids 
given to accelerate fetal lung maturation. Building on the effects seen 
at 48 hours and in earlier gestations at 7 days, the next clinical study 
will explore a range of doses to fully define and optimize the full 
therapeutic potential of ebopiprant. We look forward to leveraging 
important learnings from PROLONG in this next phase of development." 
 
   "These positive data play a critical role in our development plans for 
ebopiprant, and we are excited to build on this momentum," said Brian 
O'Callaghan, CEO of ObsEva. "Preparations are ongoing to initiate a 
Phase 2b/3 clinical study in Q4:21. We believe this adaptive study has 
the potential to support an accelerated registration program in Europe, 
and we look forward to providing additional updates on our progress 
later this year. We also plan to engage the FDA in discussions regarding 
the US clinical program for ebopiprant. With no other known compounds 
under development for the treatment of preterm labor, ebopiprant has the 
potential to be an important advancement in the prevention of preterm 
birth." 
 
   The abstract, titled "A Randomised, Placebo-Controlled, Proof-of-Concept 
Trial of Ebopiprant for Spontaneous Preterm Labor (PROLONG)," will be 
presented today during an oral session by Dr. Ben Mol (Abstract #601). 
 
   Summary of the data: 
 
 
   -- Ebopiprant, when administered with atosiban infusion to women with 
      preterm labor, reduced delivery in singleton pregnancies at 48 hours 
      after the start of dosing by over 50% compared to atosiban alone. 
 
   -- Overall, 7/56 (12.5%) of women receiving ebopiprant on top of atosiban 
      delivered within 48 hours of starting treatment compared to 12/55 (21.8%) 
      receiving atosiban plus placebo (OR 90% CI: 0.52 (0.22, 1.23)). 
 
   -- In singleton pregnancies, 5/40 (12.5%) of women receiving ebopiprant plus 
      atosiban delivered within 48 hours compared to 11/41 (26.8%) receiving 
      atosiban plus placebo (OR 90% CI: 0.39 (0.15, 1.04)). 
 
   -- This difference was observed for singletons (12.5% vs 26.8%) but not for 
      twins (12.5% vs 7.1 %). 
 
   -- The treatment effect for the overall population was more modest at 7 days, 
      however in younger gestational ages, the percentage of women who 
      delivered within 7 days was lower in women receiving ebopiprant on top of 
      atosiban (23.8%) compared to women who received placebo plus atosiban 
      (14.3%) (OR 90% CI: 0.53 (0.14, 2.01)). 
 
   -- The incidence of maternal, fetal and neonatal adverse events was 
      comparable between the treatment groups. 
 
 
   The presentation is available through the RCOG conference portal, and 
the link to the session is also available under the "Events Calendar" in 
the Investors section of ObsEva's website at www.ObsEva.com 
 
   About PROLONG 
 
   The randomized, double-blind, placebo-controlled, parallel-group trial 
was designed to assess the efficacy, safety and pharmacokinetics of 
ebopiprant. In this study, 113 women (83 singletons, 30 twins) with 
spontaneous preterm labor (gestational age between 24 and 34 weeks) were 
randomized and treated with atosiban (ex-U.S. standard of care) plus 
ebopiprant or atosiban plus placebo for 7 days. There were 83 (73%) 
women with singleton pregnancies and 30 (27%) with twin pregnancies. One 
hundred and forty-one neonates were born. Ebopiprant or placebo was 
administered orally, with 1000 mg as a starting dose (within 24 hours 
after starting the atosiban infusion), then 500 mg twice a day for 7 
days. Women were assessed up to 14 days (unless delivery occurred 
sooner) and then again at delivery and up to 28 days after delivery. 
Follow-up of infants at 6, 12 and 24 months after birth. The efficacy 
endpoints assessed were delivery within 48 hours of starting treatment, 
delivery within 7 days of starting treatment, delivery before 37 weeks 
of gestation, and time to delivery. Safety assessments included maternal, 
fetal and neonatal safety. Infants are being followed-up at 6, 12 and 24 
months. For additional information on this trial (NCT03369262), please 
visit www.clinicaltrials.gov. 
 
   About Ebopiprant and PGF(2ALPHA>) 
 
   ObsEva is developing ebopiprant, a potential first-in-class, once daily, 
oral and selective prostaglandin F(2ALPHA>)  receptor antagonist, which 
is designed to control preterm labor by reducing inflammation, 
decreasing uterine contractions, preventing cervical changes and fetal 
membrane rupture without causing the potentially serious side effects to 
the fetus seen with non-specific prostaglandin synthesis inhibitors 
(NSAIDs). PGF(2ALPHA>)  is believed to induce contractions of the 
myometrium and also upregulate enzymes causing cervix dilation and 
membrane rupture. In nonclinical studies, ObsEva has observed that 
ebopiprant markedly reduces spontaneous and induced uterine contractions 
in pregnant rats without causing the fetal side effects seen with 
non-specific prostaglandin inhibitors such as indomethacin. Ebopiprant 
(OBE022) was licensed from Merck KGaA, Darmstadt, Germany, in 2015. 
ObsEva retains worldwide, exclusive, commercial rights. 
 
   About ObsEva 
 
   ObsEva is a biopharmaceutical company developing and commercializing 
novel therapies to improve women's reproductive health and pregnancy. 
Through strategic in-licensing and disciplined drug development, ObsEva 
has established a late-stage clinical pipeline with development programs 
focused on treating endometriosis, uterine fibroids and preterm labor. 
ObsEva is listed on the Nasdaq Global Select Market and is trading under 
the ticker symbol "OBSV" and on the SIX Swiss Exchange where it is 
trading under the ticker symbol "OBSN". For more information, please 
visit www.ObsEva.com. 
 
   About RCOG 
 
   The RCOG is a medical charity that champions the provision of 
high-quality women's healthcare in the UK and beyond. It is dedicated to 
encouraging the study and advancing the science and practice of 
obstetrics and gynaecology. It does this through postgraduate medical 
education and training and the publication of clinical guidelines and 
reports on aspects of the specialty and service provision. If you would 
like to request a Press pass to the congress please email 
pressoffice@rcog.org.uk 
https://www.globenewswire.com/Tracker?data=xaVY_X80ns-zdwvOoQB-hZg-stFWHjGRvZoEBcBwktSpcXmhXbGwTTSEJCw5q-u_JVho_PQ2vHmwJ9Mxr6bdAuDuuTriW6pCTt1Jlz7C4-A= 
. 
 
   Cautionary Note Regarding Forward Looking Statements 
 
   Any statements contained in this press release that do not describe 
historical facts may constitute forward-looking statements as that term 
is defined in the Private Securities Litigation Reform Act of 1995. 
These statements may be identified by words such as "believe", "expect", 
"may", "plan", "potential", "will", and similar expressions, and are 
based on ObsEva's current beliefs and expectations. These 
forward-looking statements include expectations regarding the clinical 
development of and commercialization plans for ObsEva's product 
candidates, expectations regarding regulatory and development milestones, 
including the potential timing of regulatory submissions to the EMA and 
FDA and ObsEva's ability to obtain and maintain regulatory approvals for 
its product candidates, and the results of interactions with regulatory 
authorities. These statements involve risks and uncertainties that could 
cause actual results to differ materially from those reflected in such 
statements. Risks and uncertainties that may cause actual results to 
differ materially include uncertainties inherent in the conduct of 
clinical trials and clinical development, including the risk that the 
results of earlier clinical trials may not be predictive of the results 
of later stage clinical trials, related interactions with regulators, 
ObsEva's reliance on third parties over which it may not always have 
full control, the impact of the ongoing novel coronavirus outbreak, and 
other risks and uncertainties that are described in the Risk Factors 
section of ObsEva's Annual Report on Form 20-F for the year ended 
December 31, 2020 filed with Securities and Exchange Commission (SEC) on 
March 5, 2021 and other filings ObsEva makes with the SEC. These 
documents are available on the Investors page of ObsEva's website at 
http://www.ObsEva.com. Any forward-looking statements speak only as of 
the date of this press release and are based on information available to 
ObsEva as of the date of this release, and ObsEva assumes no obligation

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