G1 pitches IPO to advance lung and breast cancer candidates

Biotech is hoping to raise around $115 million

G1 Therapeutics thinks it has a winner on its hands with CDK4/6 inhibitor trilaciclib and is embarking on an initial public offering to give it the resources it needs to bring it to market.

The Research Triangle Park biotech says it is hoping to raise around $115 million from the IPO, which comes a little over a year after G1 raised $47 million in a venture round on the strength of some early-stage data for its lead drug.

Going public signals G1's increasing confidence  in trilaciclib (G1T28), which is in the same class as Pfizer's Ibrance (palbociclib)—the first drug of this type to reach the market in 2015 and already a $2 billion-a-year blockbuster—and Novartis' new entrant Kisqali (ribociclib). Eli Lilly is also nipping at the CDK4/6leaders' heels with its abemaciclib prospect, due to report late-stage data shortly.

G1 is walking a very different path with trilaciclib compared to its rivals, however, positioning its intravenously-administered drug as a means of protecting bone marrow and other healthy cells in the body from the damaging effects of chemotherapy, rather than targeting tumors dependent on the CDK4/6 pathway to proliferate and grow.

The rationale behind the drug is that it stops bone marrow cells from dividing while chemotherapy is being delivered – protecting them from its damaging effects – with the cells resuming their normal activity after the round of chemotherapy is completed. G1 also says the drug enhances immune system function by activating T cells.

The biotech's chief executive Mark Velleca, M.D., Ph.D., sees the short-acting drug as a first-in-class CDK4/6 inhibitor that sits apart from the current crop of oral drugs, although G1 is also developing its own oral candidate—G1T38—which he reckons could be a best-in-class rival to Ibrance et al and is just starting a phase 1b/2a trial.

G1 says it will use the net proceeds from the IPO to fund the development of trilaciclib and G1T38, as well as a preclinical-stage product candidate for breast cancer due to start trials around the turn of the year.

Trilaciclib is being developed for CDK4/6-independent tumors, namely small cell lung cancer (SCLC) and triple-negative breast cancer (TNBC), while G1T38 will be targeted at non-small cell lung cancer. For the moment, Ibrance and Kisqali are approved for breast cancer only but both Pfizer and Novartis are looking at extending the use of their drugs into multiple other solid tumors.

G1 has three phase 2 trials ongoing in SCLC and one phase 2 study in TNBC, with results due in the next 12 to 18 months.