Plexium adds industry vet Mike Grey to the brain trust with new investor cash funding its protein degradation play
About 15 months since closing a $28 million Series A, a San Diego protein-degradation upstart returned to the venture well Thursday with an extension of that round and some new hires, including one of the city’s best-connected biotech execs.
Plexium has bagged an additional $35 million in financing, the biotech said, money that will push undisclosed oncology and immuno-oncology programs into the clinic. In addition, longtime industry vet Mike Grey is jumping on as chairman of the board, and two others from Thursday’s leads — Adam Goulburn from Lux Capital and Rob Hopfner from Pivotal bioVentures — joined the board too.
“Mike Grey has a long history in the pharmaceutical industry, as an entrepreneur, as an executive, as a multiple-time CEO,” CEO Swamy Vijayan told Endpoints News. “More specifically, he has led and has been CEO of platform companies, utilizing technology to derive therapeutic programs and advancing them into the clinic. He brings that perspective.”
Since the company’s founding in 2018, Vijayan has focused on what he says is an atypical approach to protein degradation. Where most big players in the field like Arvinas and Kymera focus on small molecules that bind to a protein’s active site, Vijayan said, Plexium researchers put their efforts toward “monovalent” protein degraders that bind either to a cell’s machinery or the cell itself.
The previous financing was mainly used to scale up the biotech’s screening platform, which builds on DNA encoded libraries and integrates cell-based assays to allow for deeper exploration of the tests. Vijayan said it amounts to an entire drug discovery infrastructure in a bench-top device, allowing for anywhere between 150,000 to 1 million experiments to take place at once.
“It’s not a traditional pharma where you have chemistry and biology; you actually have an engineering team … to allow drug discovery at this scale,” Vijayan said of the platform.
Thursday’s raise helps advance their in-house monovalent candidates, however, utilizing a method Vijayan said goes after targets many consider undruggable and opens the door to using protein degradation as a modality. By running so many experiments in the screening process, Plexium is able to predict how proteins might react to certain compounds.
“Basically you want to push the protein into a conformation it normally doesn’t exist in,” Vijayan said. Plexium’s programs “push and perturb” protein surfaces into a new conformation, ultimately leading to degradation because “the cell now doesn’t know what to do with it” and registers the protein as misfolded.
In the context of cancer, Plexium claims its programs can tamp down on the overexpression of certain transcription factors that cause tumor growth. Rather than creating a drug to influence this process, Vijayan’s goal is to degrade the proteins here altogether.
With the new funding Thursday, Plexium will have enough cash for the next two years, allowing the company to nominate a program for clinical development by the end of 2021 and hopefully wrap up IND-enabling studies as 2022 comes to a close.
Thursday’s funding was led by Lux Capital and Pivotal bioVentures, with participation from The Column Group, DCVC Bio and other current investors.