March 21, 2019

Gelesis Announces Three Presentations at Annual Endocrine Society Meeting

BOSTON, Massachusetts, March 21, 2019 — Gelesis, a biotechnology company developing first-in-class mechanotherapeutics to treat obesity and other chronic diseases related to the gastrointestinal (GI) tract, today announced the Company will deliver three poster presentations at ENDO, the Endocrine Society Annual Meeting, held in New Orleans from March 23-26.

Two of the presentations will share expanded clinical data from the pivotal study of Gelesis100, an oral, non-systemic approach to weight loss. A third will highlight preclinical data suggesting a different product candidate derived from Gelesis’ proprietary hydrogel platform can restore gut barrier function in mice with severe gut wall injury.

“We are pleased to share expanded clinical data which seeks to address crucial public health issues associated with overweight and obesity. We are also excited to present our latest research on leveraging our hydrogel technology in chronic diseases of the GI system,” said Harry L. Leider, M.D., MBA, FACPE, Chief Medical Officer of Gelesis. “We look forward to discussing our findings with the scientific community.”

Details of the presentations are as follows:

Poster Title: Gelesis100 Reduces Insulin Resistance in Patients Who Are Overweight or Have Obesity with High Insulin Resistance: Results of the GLOW Study
Poster Session: P50. Obesity Mechanisms and Treatments Potpourri
Date and Time: March 25, 2019, (1:00 – 3:00 PM)

Poster Location: Poster Board #MON-112, ENDO Expo Hall, Ernest N. Morial Convention Center

Poster Title: Elevated Fasting Plasma Glucose Predicts Higher Odds for Becoming a Super-Responder with Gelesis100 in the GLOW Pivotal Weight-Loss Study
Poster Session: P05. Obesity Comorbidities and Therapies
Date and Time: Saturday, March 23, 2019 (1:00 – 3:00 PM)

Poster Location: Poster Board # SAT-LB023, ENDO Expo Hall, Ernest N. Morial Convention Center

Poster Title: Gelesis Novel, Non-Systemic, Superabsorbent Hydrogel Improves Intestinal Barrier Function in Intestinal Injury Pre-Clinical Model
Poster Session: P50. Obesity Mechanisms and Treatments Potpourri
Date and Time: Monday, March 25, 2019 (1:00 – 3:00 PM)

Poster Location: Poster Board # MON-LB022, ENDO Expo Hall, Ernest N. Morial Convention Center

About Gelesis 100

Gelesis100 is a non-systemic, superabsorbent hydrogel in development for the potential treatment of overweight or obesity. It is made from two naturally derived building blocks, modified cellulose cross- linked with citric acid, that create a three-dimensional matrix. Orally administered in capsules with water before a meal, Gelesis100 particles rapidly absorb water in the stomach and homogenously mix with ingested foods. When hydrated, Gelesis100 occupies about one-fourth of the average stomach volume. Rather than forming one large mass, it creates thousands of small individual gel pieces with the elasticity (firmness) of solid ingested foods (e.g., vegetables) without caloric value. Gelesis100 maintains its three- dimensional structure and mechanical properties during transit through the small intestine. Once it arrives in the large intestine, the hydrogel is partially broken down by enzymes and loses its three-dimensional structure along with most of its absorption capacity. The released water is reabsorbed in the large intestine, and the remaining cellulosic material is expelled in the feces. Gelesis100 is considered a medical

device because it achieves its primary intended purpose through mechanical modes of action consistent with mechanobiology constructs. Gelesis100 received a Non-Significant Risk (NSR) designation by the FDA.

This investigational product has been studied in more than 450 patients (excluding patients treated by placebo) across five clinical studies throughout the United States, Canada, and Europe. Other than an increase in overall gastrointestinal adverse events (AEs), most of which were assessed as mild, there was no difference in the incidence and severity of AEs between the Gelesis100 and placebo groups. In both treatment groups, most AEs were mild or moderate in intensity. No serious adverse events were observed in the Gelesis100 group. Gelesis100 is pending De Novo clearance and is not available for sale in the United States.

About Gelesis

Gelesis is developing a novel mechanobiology platform technology to treat obesity and other chronic diseases related to the GI pathway. Gelesis’ proprietary approach is designed to act mechanically in the GI pathway to potentially alter the course of chronic diseases. In September 2017, Gelesis completed a pivotal trial for weight loss evaluating its lead investigational product candidate Gelesis100. Additionally, Gelesis is conducting a proof-of-concept study for its second candidate, Gelesis200, which is optimized for weight loss and glycemic control in patients with type 2 diabetes and prediabetes. Novel hydrogel mechanotherapeutics based on the Gelesis platform technology are also being advanced through a pipeline with preclinical studies in other GI-related conditions such as non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), and inflammatory bowel disease (IBD).

The Gelesis executive and advisory team includes some of the world’s leading experts in obesity, chronic disease research, and materials science. Gelesis was co-founded by PureTech Health (LSE: PRTC), an advanced, clinical-stage biopharmaceutical company. For more information, visit www.gelesis.com or connect with us on Twitter @GelesisInc.

Contact:

Investors
Kathryn McNeil
+1 347 204 4226 kmcneil@gelesis.com

U.S. media
Tom Donovan
+1 857 559 3397 tom@tenbridgecommunications.com