Ribon Therapeutics Snags $65 Million to Advance Lead Candidates


With a fresh $65 million infusion of cash, Ribon Therapeutics continues to blaze a trail in the development of therapeutics that target novel enzyme families activated under cellular stress conditions.

The Lexington, Mass.-based company is focused on monoPARP inhibitors, a subclass of PARP enzymes that have been key players in regulating stress responses that can enable cancer cells to proliferate and avoid detection. 

Cancer cells are devious and can hijack alternative pathways that are not required by healthy cells and ultimately use them as stress support highways, Ribon said on its website. This allows cancer cells to proliferate and evade an antitumor response from the immune system. By focusing on the stress support pathways, Ribon believes this provides a novel approach to targeting cancer. 

Ribon’s lead oncology asset, RBN-2397, is an inhibitor of PARP7, which is upregulated in response to cellular stress. Chief Executive Officer Victoria Richon, who formerly oversaw the discovery and preclinical research in oncology at Sanofi, told BioSpace in an interview that RBN-2397 plays a role in regulating interferon signaling in the tumor. PARP7, which is overexpressed in multiple solid tumors, including squamous cell carcinoma of the lung, acts as a brake on the cellular stress response by negatively regulating the Type I interferon response. 

In preclinical studies, inhibition of PARP7 has been shown to directly impact cellular proliferation, which leads to the restoration of interferon signaling. That, in turn, stimulates an innate and adaptive antitumor immune response. RBN-2397 is currently in Phase 1 clinical trial as a monotherapy in patients with advanced solid tumors. 

At the American Society of Clinical Oncology meeting last month, Ribon presented Phase I data showing RBN-2397 is well-tolerated. Additionally, in a heavily pre-treated heterogeneous population, the data showed preliminary antitumor activity was observed in some patients.

RBN-2397 is currently being assessed as a monotherapy, but Ribon has plans to pair the asset with Merck’s vaunted checkpoint inhibitor, Keytruda, as a potential treatment for solid tumors. 

The company’s second lead asset is RBN-3143, a PARP14 inhibitor, which regulates the IL4 signaling pathway. Richon said they understand this pathway to play a key signaling role in inflammatory disease. RBN-3143 is currently in preclinical development, but Ribon hopes to move this asset into human trials early next year. 

Ribon’s drug candidates were developed with its proprietary BEACON (Blocking the Enzyme Activity Component of NAD+) platform. 

The latest financing round was led by Deerfield Management and U.S. Venture Partners. New investors who took part in the round include Avego BioScience Capital, GV (formerly Google Ventures), Monashee Investment Management and Peregrine Ventures. Existing investors, including AbbVie Ventures, Bristol Myers Squibb, Euclidean Capital, Johnson & Johnson Innovation – JJDC, Inc., Novartis Venture Fund, Osage University Partners, Takeda Ventures and The Column Group, also participated in the financing round. 

Richon expressed her excitement about the investor support the company has received. She said the financing will help the company realize its goal of developing novel, first-in-class treatments that provide help to patients in need.

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