Tessera Therapeutics Appoints Joseph Romanelli as President and Chief Executive Officer

Veteran pharmaceutical executive to lead Tessera's next phase of growth as the company advances Gene Writing from platform innovation toward a broad clinical pipeline of genetic medicines

SOMERVILLE, Mass., July 23, 2026 /PRNewswire/ -- Tessera Therapeutics ("Tessera"), the biotechnology company pioneering a new approach to genetic medicine known as Gene Writing™, today announced the appointment of Joseph Romanelli as President and Chief Executive Officer. Romanelli succeeds Michael Severino who has led the company since June 2022. Romanelli will join Tessera's board of directors and also join Tessera's founder, Flagship Pioneering, as a CEO-Partner.

The leadership transition comes as Tessera has advanced its first in vivo gene editing program, TSRA-196, into the clinic and is poised to progress a growing pipeline of Gene Writing medicines, including a development candidate for sickle cell disease and efforts towards in vivo chimeric antigen receptor (CAR)-T for oncology and autoimmune diseases. TSRA-196 is being jointly developed and commercialized with Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) for the treatment of alpha-1 antitrypsin deficiency (AATD). In addition, Tessera has received an investment of up to $50 million from the Gates Foundation to develop a globally accessible in vivo gene editing therapy for sickle cell disease.

"Over the past several years, Tessera has established the scientific and technological foundation for Gene Writing. The company's next chapter is translating that foundation into a broad portfolio of medicines and Joe is the right leader to guide that transition," said Geoff von Maltzahn, Ph.D., co-founder, founding CEO, and Chairman of Tessera and General Partner at Flagship Pioneering. "Joe has spent more than three decades building teams, forging partnerships, and commercializing innovative medicines across global markets. His experience scaling organizations, leading international businesses, and bringing breakthrough therapies to patients makes him exceptionally well suited to lead Tessera as it evolves from a company focused primarily on platform innovation and preclinical development into one capable of realizing the full potential of Gene Writing."

Von Maltzahn continued: "We are deeply grateful to Mike Severino for his leadership over the past four years and wish him every success in the future as he embarks on a new role leading a commercial stage biotech company."

Romanelli joins Tessera from Merck & Co., Inc. (NYSE: MRK) where he most recently served as President, Human Health International, and a member of the company's Executive Team. In that role, he was responsible for Merck's more than $25 billion international human health business, leading teams across 75 markets outside the United States. From 2016 through 2021, he led Merck's business in China, where the company became one of the fastest growing multinational pharmaceutical businesses in the country and China became Merck's second-largest market. During his nearly 30-year career at Merck, Romanelli held a series of strategic and operational positions of increasing responsibility, including multiple roles that culminated in leadership of the company's investor relations function. He received his bachelor's degree from the University of Delaware and MBA from Fordham University's Gabelli School of Management.

"With its Gene Writing technologies and pipeline, Tessera has an exceptional opportunity to help shape the next era of medicine where it may be possible to not only alleviate symptoms, but to address the underlying genetic cause of disease," said Romanelli. "Tessera has built a remarkable scientific platform and assembled an outstanding team. I'm excited to work alongside them to advance a broad pipeline of Gene Writing medicines through clinical development with the goal of ultimately delivering these therapies to patients around the world."

About Tessera Therapeutics

Tessera Therapeutics is a clinical-stage biotechnology company pioneering an innovative approach to genome engineering through the development of its Gene Writing™ and delivery platforms, with the goal of advancing in vivo genetic medicines. Our Gene Writing platform utilizes all-RNA constructs and is designed to write therapeutic messages into the genome by leveraging a process known as target-primed reverse transcription (TPRT) to efficiently change single or multiple DNA base pairs or add exon-length sequences or whole genes. Our proprietary lipid nanoparticle delivery platform is designed to enable the in vivo delivery of RNA to targeted cell types. We believe our Gene Writing and delivery platforms position us to advance differentiated in vivo genetic medicines designed to not only cure monogenic diseases but also create engineered cells to fight cancer and autoimmune disease and modify inherited risk factors to treat common diseases. Tessera Therapeutics was founded in 2018 by Flagship Pioneering, a life sciences innovation enterprise that invents and builds platform companies, each with the potential for multiple products that transform human health, sustainability, and beyond.

For more information about Tessera, please visit www.tesseratherapeutics.com.

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SOURCE Tessera Therapeutics