G1 Therapeutics Unveils Positive Mid-Stage Data for Myelopreservation in SCLC Patients


A mid-stage program aimed at treating myelosuppression in lung cancer patients undergoing chemotherapy is yielding positive results.

North Carolina-based G1 Therapeutics said its Phase IIa short-acting CDK4/6 inhibitor trilaciclib preserved bone marrow and immune system function in some patients undergoing chemotherapy for first-line small cell lung cancer (SCLC). Trilaciclib is being developed to preserve hematopoietic stem cells and enhance immune system function (myelopreservation) during chemotherapy. Founded in 2008 as a spinout from the University of North Carolina, G1 Therapeutics is developing cyclin-dependent kinases (CDKs), with a particular focus on CDK4 and CDK6.

Trilaciclib is administered intravenously prior to chemotherapy. G1’s Chief Medical Officer Raj Malik said the myelopreservation effects demonstrated by trilaciclib during the Phase IIa trial improved patient outcomes.

“Chemotherapy continues to be a cornerstone of cancer treatment, and trilaciclib has the potential to benefit many of these patients,” Malik said in a statement.

Trilaciclib is being evaluated in four Phase II clinical trials: a trial in newly diagnosed, treatment-naive SCLC patients, a trial in previously treated SCLC patients, a trial in patients with triple-negative breast cancer and a trial in combination with AstraZeneca’s Tecentriq and chemotherapy in SCLC patients.

Data from the Phase IIa trial showed trilaciclib reduced “clinically relevant consequences of chemotherapy-induced myelosuppression” in comparison to placebo. G1 said rrilaciclib was well tolerated, with no Grade 3/4 trilaciclib-related treatment-emergent adverse events reported. Trilaciclib showed favorable trends versus placebo for overall response rate (ORR), duration of response (DOR), and progression-free survival (PFS), the company said.

Key hematological results indicated a nearly 93 percent reduction in patients with Grade 4 Neutropenia in Cycle 1. Patients with febrile neutropenia saw a 67.9 percent hematological reduction. The lowest hematological reduction was at 41.6 percent in patients with chemotherapy cycle delays, according to the company’s data. The company plans to share these data with U.S. and European regulatory authorities this year and discuss next steps for the development of trilaciclib. The company also plans to present results from this trial, including updated data from the Phase 1b portion, at a medical meeting later this year.

G1 Chief Executive Officer Mark Velleca said the strength of the Phase IIa dataset provides the company with a “solid foundation” to advance the development of trilaciclib through Phase III and into commercialization. Velleca said there is “significant interest” from companies in combining trilaciclib with checkpoint inhibitor/chemotherapy regimens. 

“We believe that trilaciclib has the potential to become backbone therapy for multiple chemotherapeutic regimens across a variety of cancer types, delivering significant benefits to patients and creating a substantial long-term commercial opportunity,” Velleca said in a statement.

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