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Trade namesCosela
  • 4-[[5-(4-methylpiperazin-1-yl)pyridin-2-yl]amino]spiro[1,3,5,11-tetrazatricyclo[,7]trideca-2,4,6,8-tetraene-13,1'-cyclohexane]-10-one
Clinical data
Drug classCyclin-dependent kinase (CDK) inhibitor
Main usesPrevention of chemotherapy-induced bone marrow suppression[1]
Side effectsTiredness, low calcium, low potassium, low phosphate, headache, pneumonia[1]
Routes of
Typical dose240 mg/m2[1]
External links
License data
Legal status
Chemical and physical data
Molar mass446.559 g·mol−1
3D model (JSmol)
  • InChI=1S/C24H30N8O/c1-30-9-11-31(12-10-30)18-5-6-20(25-15-18)28-23-26-14-17-13-19-22(33)27-16-24(7-3-2-4-8-24)32(19)21(17)29-23/h5-6,13-15H,2-4,7-12,16H2,1H3,(H,27,33)(H,25,26,28,29)

Trilaciclib, sold under the brand name Cosela, is a medication used to reduce chemotherapy-induced bone marrow suppression.[1] Specifically it is used before platinum and etoposide or topotecan treatment for small cell lung cancer.[1] It is given by injection into a vein.[1]

Common side effects include tiredness, low calcium, low potassium, low phosphate, headache, and pneumonia.[1] Other side effects may include allergic reactions, pain at the site of injection, and pneumonitis.[1] Use in pregnancy may harm the baby.[1] It works by temporarily blocking CDK4 and CDK6.[1]

Trilaciclib was approved for medical use in the United States in 2021.[1] It is not available in Europe or the United Kingdom as of 2022.[3] In the United States it costs about 1,600 USD for 300 mg as of 2022.[4]

Medical uses

Trilaciclib is indicated to reduce the frequency of chemotherapy-induced bone marrow suppression in adults receiving certain types of chemotherapy for extensive-stage (when the cancer has spread beyond the lungs) small cell lung cancer.[1][2]


It is used at a dose of 240 mg/m2 within 4 hours of chemotherapy.[1]

Mechanism of action

Chemotherapy drugs are designed to kill cancer cells but can damage normal tissues as well.[2] The bone marrow is particularly susceptible to chemotherapy damage.[2] The bone marrow makes red blood cells, white blood cells, and platelets (small fragments in the blood) that transport oxygen, fight infection, and stop bleeding.[2] When damaged, the bone marrow produces fewer of these cells, leading to fatigue, increased risk of infection, and bleeding, among other problems.[2] Trilaciclib may help protect the normal bone marrow cells from the harmful effects of chemotherapy.[2]


The effectiveness of trilaciclib was evaluated in three randomized, double-blind, placebo-controlled studies in participants with extensive-stage small cell lung cancer.[2] Combined, these studies randomly assigned 245 participants to receive either an infusion of trilaciclib in their veins or a placebo before chemotherapy.[2] The studies then compared the two groups for the proportion of participants with severe neutropenia (a very low count of white blood cells called neutrophils) and the duration of severe neutropenia in the first cycle of chemotherapy.[2] In all three studies, participants who received trilaciclib had a lower chance of having severe neutropenia compared to participants who received a placebo.[2] Among those who had severe neutropenia, participants who received trilaciclib, on average, had it for a shorter time than participants who received a placebo.[2]

The U.S. Food and Drug Administration (FDA) granted the application for trilaciclib priority review and breakthrough therapy designations.[2] The FDA granted the approval of Cosela to G1 Therapeutics, Inc.[2]


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 "Cosela- trilaciclib injection, powder, lyophilized, for solution". DailyMed. Archived from the original on 24 June 2021. Retrieved 17 June 2021.
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 "FDA Approves Drug to Reduce Bone Marrow Suppression Caused by Chemotherapy". U.S. Food and Drug Administration (FDA) (Press release). 12 February 2021. Archived from the original on 14 June 2021. Retrieved 12 February 2021. Public Domain This article incorporates text from this source, which is in the public domain.
  3. "Trilaciclib". SPS - Specialist Pharmacy Service. 21 August 2020. Archived from the original on 2 February 2022. Retrieved 31 October 2022.
  4. "Cosela Prices, Coupons, Copay & Patient Assistance". Retrieved 31 October 2022.

 This article incorporates public domain material from the United States Department of Health and Human Services website

External links

External sites:
  • Clinical trial number NCT03041311 for "Carboplatin, Etoposide, and Atezolizumab With or Without Trilaciclib (G1T28), a CDK 4/6 Inhibitor, in Extensive Stage Small Cell Lung Cancer (SCLC)" at
  • Clinical trial number NCT02499770 for "Trilaciclib (G1T28), a CDK 4/6 Inhibitor, in Combination With Etoposide and Carboplatin in Extensive Stage Small Cell Lung Cancer (SCLC)" at
  • Clinical trial number NCT02514447 for "Trilaciclib (G1T28), a CDK 4/6 Inhibitor, in Patients With Previously Treated Extensive Stage SCLC Receiving Topotecan Chemotherapy" at