Abemaciclib in combination with therapies for patients with metastatic breast cancer: a phase 1b study

BackgroundThe oral, selective, and potent small molecule cyclin-dependent kinases (CDK) 4/6 inhibitor (CDK4/6i) abemaciclib has demonstrated efficacy in advanced breast cancer and high-risk early breast cancer. This Phase 1b study evaluated the safety, tolerability, pharmacokinetics, and antitumor a...

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Main Authors: Sara M. Tolaney, Komal Jhaveri, Teresa Helsten, Shannon L. Puhalla, Alison Conlin, E. Claire Dees, Muralidhar Beeram, Sonya C. Chapman, Andrew Lithio, Lacey M. Litchfield, Matthew P. Goetz
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Language:English
Published: Frontiers Media S.A. 2025-03-01
Series:Frontiers in Oncology
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Online Access:https://www.frontiersin.org/articles/10.3389/fonc.2025.1555921/full
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author Sara M. Tolaney
Komal Jhaveri
Teresa Helsten
Shannon L. Puhalla
Alison Conlin
E. Claire Dees
Muralidhar Beeram
Sonya C. Chapman
Andrew Lithio
Lacey M. Litchfield
Matthew P. Goetz
author_facet Sara M. Tolaney
Komal Jhaveri
Teresa Helsten
Shannon L. Puhalla
Alison Conlin
E. Claire Dees
Muralidhar Beeram
Sonya C. Chapman
Andrew Lithio
Lacey M. Litchfield
Matthew P. Goetz
author_sort Sara M. Tolaney
collection DOAJ
description BackgroundThe oral, selective, and potent small molecule cyclin-dependent kinases (CDK) 4/6 inhibitor (CDK4/6i) abemaciclib has demonstrated efficacy in advanced breast cancer and high-risk early breast cancer. This Phase 1b study evaluated the safety, tolerability, pharmacokinetics, and antitumor activity of abemaciclib in combination with endocrine therapies (Parts A–D), exemestane + everolimus (Part E), or fulvestrant + LY3023414 (a PI3K/mTOR inhibitor; Part G) in patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC), or trastuzumab (Part F), or trastuzumab + pertuzumab (Part H) in patients with HER2-positive (HER2+) MBC.Patients and methodsThis study enrolled women aged ≥18 years old with either HR+, HER2- (Parts E and G), or HER2+ (Parts F and H) MBC. Additional requirements included measurable disease or non-measurable but evaluable bone disease (Parts E and F), or measurable disease (Parts G and H), an Eastern Cooperative Oncology Group performance status of 0–1, and no prior treatment with CDK4/6i (Parts E, F, and H). Adverse events were graded, and tumor response was assessed.ResultsNineteen patients in Part E received abemaciclib (150 mg, n=15; 200 mg, n=4) with exemestane + everolimus, 24 patients in Part F received abemaciclib (150 mg, n=18; 200 mg, n=6) with trastuzumab, 12 patients in Part G received 150 mg abemaciclib with fulvestrant + LY3023414 (100 mg, n=7; 150 mg, n=5), and four patients in Part H received abemaciclib (100 mg) with trastuzumab + pertuzumab (with prophylactic loperamide). The most common treatment-emergent adverse events (TEAEs) were diarrhea, fatigue, neutropenia, and nausea. Grade ≥3 TEAEs were reported in 16, 18, 10, and 4 patients in Parts E–H, respectively. Abemaciclib had no effect on the pharmacokinetics of the combination study drugs. The objective response rates for patients with measurable disease were 46.2%, 10.0%, 66.7%, and 25.0% in Parts E–H, respectively. A recommended Phase 2 dose was not established for Parts E, G, and H at the dose levels evaluated, and was determined to be 150 mg Q12H in Part F.ConclusionsOverall, our results demonstrate safety profiles consistent with those previously established for abemaciclib and provide preliminary data for these combination therapies in the treatment of HR+, HER2- or HER2+ MBC.
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spelling doaj-art-e103c481c50146c49f246016e0728d6d2025-08-20T02:47:52ZengFrontiers Media S.A.Frontiers in Oncology2234-943X2025-03-011510.3389/fonc.2025.15559211555921Abemaciclib in combination with therapies for patients with metastatic breast cancer: a phase 1b studySara M. Tolaney0Komal Jhaveri1Teresa Helsten2Shannon L. Puhalla3Alison Conlin4E. Claire Dees5Muralidhar Beeram6Sonya C. Chapman7Andrew Lithio8Lacey M. Litchfield9Matthew P. Goetz10Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, United StatesDepartment of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, United StatesMoores Cancer Center, University of California San Diego, San Diego, CA, United StatesUPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, United StatesProvidence Cancer Center, Portland, OR, United StatesLineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United StatesSouth Texas Accelerated Research Therapeutics, San Antonio, TX, United StatesEli Lilly and Company, Indianapolis, IN, United StatesEli Lilly and Company, Indianapolis, IN, United StatesEli Lilly and Company, Indianapolis, IN, United StatesDepartment of Oncology, Mayo Clinic, Rochester, MN, United StatesBackgroundThe oral, selective, and potent small molecule cyclin-dependent kinases (CDK) 4/6 inhibitor (CDK4/6i) abemaciclib has demonstrated efficacy in advanced breast cancer and high-risk early breast cancer. This Phase 1b study evaluated the safety, tolerability, pharmacokinetics, and antitumor activity of abemaciclib in combination with endocrine therapies (Parts A–D), exemestane + everolimus (Part E), or fulvestrant + LY3023414 (a PI3K/mTOR inhibitor; Part G) in patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC), or trastuzumab (Part F), or trastuzumab + pertuzumab (Part H) in patients with HER2-positive (HER2+) MBC.Patients and methodsThis study enrolled women aged ≥18 years old with either HR+, HER2- (Parts E and G), or HER2+ (Parts F and H) MBC. Additional requirements included measurable disease or non-measurable but evaluable bone disease (Parts E and F), or measurable disease (Parts G and H), an Eastern Cooperative Oncology Group performance status of 0–1, and no prior treatment with CDK4/6i (Parts E, F, and H). Adverse events were graded, and tumor response was assessed.ResultsNineteen patients in Part E received abemaciclib (150 mg, n=15; 200 mg, n=4) with exemestane + everolimus, 24 patients in Part F received abemaciclib (150 mg, n=18; 200 mg, n=6) with trastuzumab, 12 patients in Part G received 150 mg abemaciclib with fulvestrant + LY3023414 (100 mg, n=7; 150 mg, n=5), and four patients in Part H received abemaciclib (100 mg) with trastuzumab + pertuzumab (with prophylactic loperamide). The most common treatment-emergent adverse events (TEAEs) were diarrhea, fatigue, neutropenia, and nausea. Grade ≥3 TEAEs were reported in 16, 18, 10, and 4 patients in Parts E–H, respectively. Abemaciclib had no effect on the pharmacokinetics of the combination study drugs. The objective response rates for patients with measurable disease were 46.2%, 10.0%, 66.7%, and 25.0% in Parts E–H, respectively. A recommended Phase 2 dose was not established for Parts E, G, and H at the dose levels evaluated, and was determined to be 150 mg Q12H in Part F.ConclusionsOverall, our results demonstrate safety profiles consistent with those previously established for abemaciclib and provide preliminary data for these combination therapies in the treatment of HR+, HER2- or HER2+ MBC.https://www.frontiersin.org/articles/10.3389/fonc.2025.1555921/fullabemaciclibmetastatic breast cancerCDK4CDK6everolimusexemestane
spellingShingle Sara M. Tolaney
Komal Jhaveri
Teresa Helsten
Shannon L. Puhalla
Alison Conlin
E. Claire Dees
Muralidhar Beeram
Sonya C. Chapman
Andrew Lithio
Lacey M. Litchfield
Matthew P. Goetz
Abemaciclib in combination with therapies for patients with metastatic breast cancer: a phase 1b study
Frontiers in Oncology
abemaciclib
metastatic breast cancer
CDK4
CDK6
everolimus
exemestane
title Abemaciclib in combination with therapies for patients with metastatic breast cancer: a phase 1b study
title_full Abemaciclib in combination with therapies for patients with metastatic breast cancer: a phase 1b study
title_fullStr Abemaciclib in combination with therapies for patients with metastatic breast cancer: a phase 1b study
title_full_unstemmed Abemaciclib in combination with therapies for patients with metastatic breast cancer: a phase 1b study
title_short Abemaciclib in combination with therapies for patients with metastatic breast cancer: a phase 1b study
title_sort abemaciclib in combination with therapies for patients with metastatic breast cancer a phase 1b study
topic abemaciclib
metastatic breast cancer
CDK4
CDK6
everolimus
exemestane
url https://www.frontiersin.org/articles/10.3389/fonc.2025.1555921/full
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