Ribon Therapeutics is looking to break the mold for PARP inhibitors and has a slate of Big Pharma backers on board
Ribon Therapeutics broke three years of radio silence back in early 2019 to spread the word of its $65 million Series B round. Now, two and a half years later, the company’s lead PARP inhibitor has investors reaching a little deeper into their pockets.
CEO Victoria Richon unveiled a $65 million Series B1 round on Wednesday, which she described as an extension of the B round closed at the end of 2018. The latest round, led by Deerfield Management and US Venture Partners, brings the Cambridge, MA-based biotech’s total raise up to about $175 million. A slate of Big Pharma players also chipped in, including AbbVie Ventures, Bristol Myers Squibb, Johnson & Johnson Innovation, Takeda Ventures and the Novartis Venture Fund.
When asked if a public debut is in Ribon’s future, Richon, a Sanofi vet, responded: “This financing enables us to move our current programs forward, and we’re always going to be evaluating all opportunities available to us to continue to advance Ribon on as a company, and to bring our programs to as many patients as we can, and as quickly as possible.”
For now, the extra cash will support the company’s two lead programs: a Phase I PARP7 inhibitor dubbed RBN-2397 in cancer, and a preclinical PARP14 inhibitor called RBN-3143 in inflammation.
The growing class of PARP inhibitors on the market includes AstraZeneca and Merck’s Lynparza, Pfizer’s Talzenna, Clovis’ Rubraca and GlaxoSmithKline’s Zejula. They all primarily target PARP1 (with some also inhibiting PARP2 and PARP3), which is a protein used by damaged cells to initiate repair. Unlike those drugs, RBN-2397 targets PARP7, a different protein similarly activated by stress and cellular response mechanisms. By blocking PARP7, the candidate is designed to enable tumor cells to secrete interferon, restoring Type I interferon signaling.
“We look at ourselves as pioneers,” Richon told Endpoints News upon announcing the Series B in early 2019.
At #ASCO21, Ribon presented interim Phase I data that showed RBN-2397 was well-tolerated and showed preliminary antitumor activity in patients with solid tumors. In the heavily pretreated population, one partial response was observed in a patient with HR+ breast cancer, and nine others achieved stable disease after four months, according to Ribon.
Richon says the team has completed the dose-escalation portion of that trial and is just now getting into expansion cohorts. RBN-3143, on the other hand, is anticipated to enter clinical testing next year.
“We know that cellular stress plays a major role in many diseases,” Richon said. “And so we’re pioneering the development of first-in-class small molecule inhibitors against this extended PARP family of enzymes, and really have found very important new biology as now shown with RBN-2397 and RBN-3143.”
Avego BioScience Capital, GV (formerly Google Ventures), Monashee Investment Management, Peregrine Ventures, Euclidean Capital, Osage University Partners and The Column Group also chipped into the Series B1 round.