Discussing the Benefits of Trilaciclib Plus Topotecan for Treatment of Extensive-stage SCLC

Lowell L. Hart, MD, FACP, scientific director of clinical research, Florida Cancer Specialists, and associate professor of medicine, Wake Forest University School of Medicine, discusses the effect of CDK4/6 inhibitor, trilaciclib (G1T28) on myelosuppression in patients with previously treated extensive-stage small cell lung cancer receiving topotecan. Hart presented the phase II results from the blinded, multicenter study during the 2019 ASCO Annual Meeting.

CDK4/6 inhibition prevents sensitive cells from going through the cell cycle, says Hart. Patients with small cell lung cancer lose the ability to utilize retinoblastoma, a protein that suppresses tumors. Since bone marrow cells are sensitive, the idea behind the study was to pause bone marrow cell growth with CDK4/6 inhibition to make the cells dormant until chemotherapy was administered.

For years, the standard of care for patients with small cell lung cancer was topotecan-based chemotherapy. However, because of extreme cell growth in these patients, oncologists struggled to find the right dosage that could keep blood counts normal. These patients then developed myelosuppression.

Patients in the study showed less severe chemotherapy-induced myelosuppression when the standard of care, topotecan, was combined with trilaciclib. Additionally, the trial met its primary endpoint by showing that the combination decreases the occurrence and duration of severe neutropenia. Hart and other authors of the study consider these result to be clinically significant.

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