Monte Rosa Therapeutics is capping off a fundraising spree with a $222.3 million IPO to get two of its “molecular glue” treatments into the clinic and advance its other discovery-stage programs.
The company raised $96 million in September 2020 to develop its drug discovery platform and expand its pipeline into diseases beyond cancer. It followed up with another $95 million six months later, ending the first quarter of 2021 with $168.4 million, according to a securities filing. Of course, drug development is an expensive business, and Monte Rosa filed in early June to raise up to $100 million in its IPO.
Despite being a preclinical biotech with much to prove, it bumped that IPO goal up to $213 million earlier this week, eventually collecting $222.3 million by offering 20% more shares than originally planned. But seeing a biotech go public without any human data isn’t unusual these days; even before the COVID-19 pandemic spurred interest and investment in the sector, companies had been hitting Wall Street at increasingly earlier stages of development.
Molecular glues are small molecules designed to treat disease by commandeering the body’s own protein degrading process. As their name suggests, they work by sticking proteins to each other.
Monte Rosa earmarked about $47 million to $57 million for a cancer treatment that targets GSPT1, which plays a role in cancers driven by the Myc family of transcription factors. The cash should get it through a phase 1/2 study.
Beyond GSPT1, Monte Rosa will use between $120 million and $130 million to get a second program into phase 1, a third program to an IND filing and a fourth to IND-enabling studies, according to the filing. Another $65 million to $75 million will bankroll the development of its drug discovery platform.
“[Molecular glues] work by allosterically changing the receptor surface of E3 ligases to attract a protein target,” said Monte Rosa CEO Markus Warmuth, M.D., referring to enzymes that tag proteins with ubiquitin for degradation by a protein complex called a proteasome, in a previous interview. "We have a singular focus on finding these molecules that reshape the surface of an E3 ligase and thereby attract otherwise undruggable targets.”
The best-known molecular glue medicines are thalidomide and its successor molecule lenalidomide—aka Bristol Myers Squibb’s blood cancer drug Revlimid—which both reshape an E3 ligase receptor called cereblon. However, this class of drugs hasn’t been hunted in a systematic way in the past, which is exactly what Monte Rosa’s technology allows it to do.
Monte Rosa isn’t alone in the protein degradation field, but it believes molecular glues can go where other approaches cannot. Other players are working on the hypothesis that eliminating disease driving proteins is a better approach than inhibiting them. They’re “redrugging the druggable,” Warmuth said, developing degraders for targets that can be inhibited by traditional drugs.
Arvinas, for example, is developing drugs called proteolysis targeting chimeras, or PROTACs, to degrade the androgen and estrogen receptors, which are major drivers of prostate cancer and breast cancer, respectively. And Kymera Therapeutics is working on degraders of scaffolding kinase IRAK4 and transcription factor STAT3, both of which play a role in cancer.
Monte Rosa wants to go after targets like GSPT1 that haven’t been accessible because drug developers didn’t have the technology to handle them.