G1 Therapeutics CEO Mark Velleca knows that three large pharmaceutical companies are researching the same cancer target as his tiny startup. But even though Velleca concedes those companies are ahead for now, he believes G1 can eventually stand out against those bigger, better-financed counterparts by taking a different approach.
Now the Research Triangle Park, NC-based company has some additional cash to try to prove it. G1 plans to announce Thursday the closing of a $33 million Series B round of financing that the company will use to study its experimental drug in additional clinical trials. Eshelman Ventures and RA Capital Management led the round, joined by new investors Lumira Capital and Boxer Capital of Tavistock Life Sciences. Existing investors Hatteras Venture Partners, MedImmune Ventures, and Mountain Group Capital also participated in the round.
G1’s approach is to intervene in the process by which cells divide and replicate. Its lead drug candidate, G1T28, pauses cell replication by inhibiting the activity of a pair of enzymes, cyclin-dependent kinases 4 and 6 (CDK4/6).
There are other CDK4/6 inhibitor drugs that work by targeting cancer cells in the process of dividing. One such drug, Pfizer’s (NYSE: PFE) palbociclib (Ibrance), this week received FDA accelerated approval to treat advanced breast cancer. Novartis’s (NYSE: NVS) LEE011 in mid-stage clinical trials and Eli Lilly’s (NYSE: LLY) abemaciclib in late-stage trials, are also CDK4/6 inhibitors.
G1’s drug can target cancer cells directly in the same way as other CDK4/6 inhibitors do. But the company also aims to address tumors such as small cell lung cancer and triple-negative breast cancer that don’t use those enzymes to divide and grow. In patients with those cancers, the G1 drug might instead be used alongside chemotherapy drugs to protect the bone marrow during treatment, as my colleague Ben Fidler explained in this profile about G1. Indeed, collateral damage to healthy marrow cells is one of the main causes of the side effects that many patients experience when undergoing chemo.
The G1 drug, administered intravenously just before chemotherapy, would pause cell division of those healthy cells, leaving the chemo, which works by killing cells that are dividing, to target only the cancer cells, Velleca explains. Once the chemotherapy was finished, the G1 drug would wash away and the marrow cells could return to dividing normally.
“The piece that’s unique to G1, and none of the competitors are pursing this, is the bone marrow protection piece,” Velleca says.
G1 is a spinout from the University of North Carolina at Chapel Hill, based on the research of Norman Sharpless, associate director for translational research at UNC’s Lineberger Comprehensive Cancer Center, and Kwok-Kin Wong, an oncologist at Dana Farber and Harvard. G1 took its first steps toward demonstrating its technology in humans with a Phase 1 clinical trial started last September, enrolling more than 40 patients. A full report of results from that study will be presented later this year at the annual meeting of the American Society of Clinical Oncology but early results suggest that the G1 drug could offer a safer and more targeted approach than the Pfizer and Novartis drugs, Velleca says.
With a drug that can work to kill cancer cells or protect the bone marrow from chemo, depending on the genetics of the tumor, Velleca says that G1 has the potential to address the majority of cancer patients. But realizing that potential will depend on the outcome of the clinical trials. With the new financing, G1 plans to start a Phase 1B trial of the intravenous form of G1T28 evaluating the compound as a chemo protectant. Velleca says that trial is expected to start by the end of the second quarter. A pill version of the G1 compound intended to target cancer cells directly could enter clinical trials toward the end of the year.