G1 Therapeutics Reports Positive Results for Cancer Therapy
A potential drug for helping cancer patients withstand the side effects of chemotherapy showed positive results in a recent Phase 2 clinical trial involving small cell lung cancer, according to its developer, G1 Therapeutics of Research Triangle Park.
The drug, trilaciclib, achieved both of its primary endpoints: reductions in the duration and occurrence of Grade 4 neutropenia, a low count of neutrophils, a type of white blood cell.
However, the drug did not outperform placebo in various measures of efficacy. The objective response rate – the proportion of patients with a certain reduction in tumor size over a set time – was well below the placebo rate (13.3 percent versus 23.1 percent). Also, the clinical benefit rate – the percentage of patients who achieve a partial or complete response and stable disease – and the median progression-free survival period were similar to placebo.
Investors apparently focused on the efficacy data, sending the company’s stock price down to a 52-week low.
The trial paired trilaciclib with the chemo drug topotecan as a treatment for second- and third-line small cell lung cancer. It was the third Phase 2 trial of trilaciclib in small cell lung cancer showing significant reductions in the duration and occurrence of Grade 4 neutropenia. Trilaciclib also lessened the need for red blood cell transfusions and granulocyte-colony stimulating factor (G-CSF) administrations – two rescue therapies for restoring blood and immune functions after chemotherapy.
“Small cell lung cancer is difficult to treat, particularly in later lines of therapy, and trilaciclib has shown potential to improve outcomes for these patients,” said Raj Malik, M.D., G1’s chief medical officer and senior vice president of R&D. “We now have four randomized Phase 2 trials showing trilaciclib’s multi-lineage myelopreservation benefits.”
Myelopreservation is the ability to protect blood cells that are created in the bone marrow.
One stock analyst reminded investors that myelopreservation, not efficacy, was the primary endpoint in the latest trial, and other analysts said they also remained bullish on trilaciclib as an under-appreciated asset.
Malik said company would meet with U.S. and European regulatory authorities in 2019 “to discuss the totality of trilaciclib data and pathways to approval.”
Trilaciclib is a short-acting inhibitor of CDK4 and CDK6, two enzymes involved in cancer formation. Inhibiting these enzymes temporarily stops hematopoietic stem cells and progenitor cells from dividing, protecting them from chemotherapy drugs that target dividing cells.
Trilaciclib, given intravenously prior to chemotherapy, is establishing its versatility. Data from the four randomized Phase 2 trials have shown myelopreservation benefits in multiple cell lines across different tumor types and in various chemotherapy regimens, said Mark Velleca, M.D., Ph.D., chief executive officer of G1.
“The totality of the data demonstrates trilaciclib’s potential to become a standard of care with chemotherapy and improve patient outcomes,” he said.
G1 is a clinical-stage oncology company with three clinical-stage programs – trilaciclib, lerociclib and G1T48 – that are designed to enable more effective combination treatment strategies and improve patient outcomes across multiple cancers.
G1 is a 2008 spin-out of the University of North Carolina at Chapel Hill. The company raised $108 million in an initial public offering of stock in 2017 after raising more than $95 million in three rounds of venture capital funding. The North Carolina Biotechnology Center provided two early-stage loans totaling $500,000.
G1 is named for the Gap 1 phase, the first of four phases of cell division in humans, plants and animals.