G1 Vets Launch Arc Therapeutics to Take on New Cancer Target

Xconomy Raleigh-Durham — 

Three early employees of G1 Therapeutics have launched a new oncology-focused company and raised $6 million to move a preclinical program licensed from their former employer into the clinic.

The startup, Research Triangle Park, NC-based Arc Therapeutics, is headed by Patrick Roberts (pictured above), who most recently served as the head of translational medicine at G1 Therapeutics (NASDAQ: GTHX). He started Arc with Jay Strum, its chief scientific officer, and John Bisi, senior vice president of research and development. Strum was also CSO at G1; Bisi served as senior director of preclinical R&D.

Financing for Arc, in addition to the scientific team and its assets, also comes from a source with G1 ties: Eshelman Ventures, whose founder Fred Eshelman, sits on its board of directors, is Arc’s founding investor.

The trio’s work at G1, which is also based in Research Triangle Park, set the firm up to ask the FDA to review its lead drug candidate, trilaciclib, in small cell lung cancer—a submission the company made in June. A kind of drug known as a CD4/6 inhibitor, it is designed to block activity of two enzymes (cyclin-dependent kinases 4 and 6) that play a role in cell proliferation. However, unlike existing CD4/6 inhibitors, G1’s potential treatment is intended to be given to patients whose tumors aren’t driven by CD4/6 before they begin chemotherapy. The drug temporarily reduces division among healthy cells, which protects them from becoming collateral damage when chemotherapy is administered. The idea is that by temporarily halting those cells’ growth, chemotherapy would home in more precisely on cancer cells, reducing side effects.

Arc, however, plans a more traditional path for the assets it licensed from G1. The startup in May inked a $2.1 million cash and equity deal to license rights to small-molecule inhibitors of a related kinase, CDK2, to treat advanced and resistant cancers. Under the deal terms G1 is eligible for an additional milestone payment and, if Arc decides to dump the assets, the first crack at negotiating their reacquisition. If the pact leads to any commercialized drugs, G1 will be eligible for royalties.

With the additional funds from Eshelman, Arc plans to select a lead compound and next year, begin the studies it will need to advance it into human testing, the company tells Xconomy.

The Arc team is going after CDK2 because of its involvement, like that of CD4/6, in driving cancer growth. It aims to develop a potential treatment for patients whose tumors don’t respond to CDK4/6 inhibition or have developed resistance to drugs designed to inhibit them.

Three CDK4/6 inhibitors have been approved for patients with certain types of breast cancer: Eli Lilly’s abemaciclib (Verzenio), Pfizer’s palbociclib (Ibrance), and Novartis’s ribociclib (Kisqali). But not all cancers rely on those enzymes; other CDK family members are also believed to drive the uncontrolled growth of cancer cells, which put Arc on the path to developing drugs that can block CDK2, according to the startup.

Strum, in a prepared statement, said while other companies have tried unsuccessfully to develop a drug that can target CDK2, the experience the Arc team gained at G1 gives it an edge.

“The rational design approach we used to develop inhibitors selective for CDK4/6 versus CDK2 at G1 Therapeutics led to a keen understanding of key structural features within the CDK2 binding pocket that can be exploited to develop a potent and selective CDK2 inhibitor,” he said.

G1 has been on a licensing streak this year. Recently it inked deals with EQRx and Genor Biopharma for the investigational cancer drug lerociclib giving the companies development and commercialization rights in the US, Europe, Japan, and all markets outside Asia-Pacific and Asia-Pacific, excluding Japan, respectively. The company also struck up a partnership with Nanjing, China-based Simcere to develop and commercialize trilaciclib, its lead drug candidate, in mainland China, Hong Kong, Macau, and Taiwan.