G1 Therapeutics Hauls in $47M for Lung, Breast Cancer Trials

Xconomy Raleigh-Durham — 

[Updated, 5/12/16, 10:25 a.m. See below.] Buoyed by promising early clinical trial results and the market traction of a similar cancer drug, G1 Therapeutics has raised $47 million to advance its lead program and start clinical trial work on another.

New investor Cormorant Asset Management led the Series C investment in Research Triangle Park, NC-based G1, and was joined by additional new investors Aju IB Investment, Cowen Private Investments, Franklin Templeton Investments, and Rock Springs Capital. Previous investors Eshelman Ventures, Hatteras Venture Partners, Lumira Capital, MedImmune Ventures, Mountain Group Capital, RA Capital, and Tavistock Life Sciences also participated in the round.

G1 is currently testing its lead drug, G1T28, in small cell lung cancer. G1 developed the intravenous drug as a way to make chemotherapy safer. The G1 drug is what’s called a CDK4/6 inhibitor, and it works by impeding the activity of a pair of enzymes (cyclin-dependent kinases 4 and 6). Blocking those enzymes pauses the cell division of healthy cells, which has the effect of protecting them from chemo, G1 says. The company reported preliminary data from Phase 1b and Phase 2a trials last month; with the funding, CEO Mark Velleca says G1 will be able to fully enroll both studies.

The capital will also enable G1 to start clinical trials on a second compound, G1T38, which Velleca says the company will study as a potential treatment for breast cancer, and later, prostate cancer. The G1 drug wouldn’t be the first CDK4/6 inhibitor for breast cancer. Pfizer (NYSE: PFE) last year won FDA approval for its CDK4/6 drug palbociclib (Ibrance). But the approval and market uptake of the Pfizer drug offers validation for the approach that G1 is taking. Novartis (NYSE: NVS) and Eli Lilly (NYSE: LLY) are also pursuing CDK4/6 inhibitor drugs in breast cancer. [Paragraph updated to clarify the cancers G1 is targeting.]

Compared with these other CDK drugs, Velleca says G1T38 could offer patients fewer side effects. The company will need to demonstrate that in clinical trials, of course. But even as G1 aims to show how its technology might bring advantages over compounds from larger pharma companies, the company is also exploring partnerships with big pharma. The G1 drugs are combination therapies meant to work with other cancer drugs. Velleca says G1 is talking with companies that are developing so-called checkpoint inhibitors, treatments that block the proteins that stop the immune system. Blocking these proteins allows the immune system to target cancer.

“There might be some synergies there with a checkpoint combo trial,” he says.

G1, a spinout from the University of North Carolina at Chapel Hill, closed a $33 million Series B round last year. Velleca says the latest round should carry the company for two years. He expects the trials will start reporting data in 2017.