Microbiome Targeted Therapeutics May Have Role in COVID-19 Fight

Prior to its COVID-19 efforts, the San Diego-based startup Persephone Biosciences, Inc., was tackling cancer and immunotherapy

Persephone Biosciences/Instagram

Some companies might be looking for an army of one to take on their tasks, startup Persephone Biosciences Inc. is looking at an army of trillions as it taps the human biome — the collection of microbes that reside in the gastrointestinal tract — with its up to 100 trillion individual cells to develop an immune boosting microbiome therapeutic to help fight coronavirus (SARS-CoV-2) as well as other illnesses including the flu and cancer.

Persephone, with its headquarters in San Diego’s JLABS’ incubator, envisions using the treatment to prevent infection, taken at the onset of symptoms, or with a vaccine or antiviral drug in order to mount an effective immune response with long-lasting immunity and also used to boost the immune system of those exposed to the virus.

The 80%

“Eighty percent of immune cells reside in the gastrointestinal tract,” said Persephone Biosciences CEO Stephanie Culler. “The microbiome is critical to promoting immune function to prevent and fight disease. Specifically, in terms of viral infections, it is really there to mount an appropriate immune response.”

Prior to its COVID-19 efforts, Persephone was tackling cancer.

“We worked in cancer and immunotherapy, primarily developing gut microbiome therapeutics to enhance efficacy of checkpoint inhibitors,” Culler said. “About two years ago, papers came out showing that gut microbiomes can very much modulate the efficacy of checkpoint inhibitors. It found 70% to 80% of those cancer patients not responding to checkpoint inhibitors had damaged mircrobiomes, low diversity and as a consequence poor immune function.”

Persephone set up a tech platform to bring together AI, patients' stool samples and blood to understand what microbes are important to patients’ immune response.

Delivered in Capsule Form

“We developed that into an orally delivered capsule that is taken with checkpoint inhibitor therapy,” Culler said. "For COVID-19, we are leveraging that treatment."

Persephone is building a big database.

The company has gotten a lot of data from Decode.Design.Cure technology platform. It collects and analyzes gut microbiome (stool) samples.

The company is also collaborating to get coronavirus stool samples. Persephone also uses next-generation genome sequencing technologies to develop novel microbiome therapeutics and diagnostics.

Culler said the company’s AI algorithm gives it a therapeutic that works on a wide variety of people tapping data from around the world.

“We believe our antiviral microbiome therapeutics have the potential to save thousands of lives by enabling robust immune responses to fight COVID-19 infection, help vaccines to have long-lasting immunity and help with future pandemics,” Culler said. “Long term we see the possibility for similar microbiome-focused therapeutics to treat multiple strains of influenza in addition to other respiratory viral infections which impact millions worldwide on a seasonal basis.”


Culler, A UC San Diego graduate who previously worked for more than six years at Genomatica, said the company raised $6 million in seed round led by Y Combinator and joined by other investors, and is looking forward to a Series A round.

Culler said she is unaware of any similar companies to Persephone doing this kind of work.

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