G1T38, a CDK 4/6 Inhibitor, in Combination With Fulvestrant in Hormone Receptor-Positive, HER2-Negative Locally Advanced or Metastatic Breast Cancer
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ClinicalTrials.gov Identifier: NCT02983071 |
Recruitment Status :
Active, not recruiting
First Posted : December 6, 2016
Last Update Posted : February 15, 2023
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This is a study to investigate the potential clinical benefit of G1T38 as an oral therapy in combination with fulvestrant in patients with hormone receptor-positive, HER2-negative metastatic breast cancer.
The study is an open-label design, consists of 2 parts: dose-finding portion (Part 1), and expansion portion (Part 2). Both parts include 3 study phases: Screening Phase, Treatment Phase, and Survival Follow-up Phase. The Treatment Phase begins on the day of first dose with study treatment and completes at the Post-Treatment Visit. Approximately, 102 patients will be enrolled in the study.
Condition or disease | Intervention/treatment | Phase |
---|---|---|
Carcinoma, Ductal, Breast Breast Cancer Breast Neoplasm | Drug: G1T38 Drug: Fulvestrant | Phase 1 Phase 2 |
Study Type : | Interventional (Clinical Trial) |
Estimated Enrollment : | 102 participants |
Allocation: | Non-Randomized |
Intervention Model: | Parallel Assignment |
Masking: | None (Open Label) |
Primary Purpose: | Treatment |
Official Title: | Phase 1/2 Safety, Pharmacokinetic, and Antitumor Activity Study of G1T38 in Combination With Fulvestrant in Patients With Hormone Receptor-Positive, HER2-Negative Locally Advanced or Metastatic Breast Cancer After Endocrine Failure |
Study Start Date : | January 2017 |
Estimated Primary Completion Date : | June 2023 |
Estimated Study Completion Date : | October 2023 |

Arm | Intervention/treatment |
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Experimental: Once-Daily G1T38 Dosing
G1T38 (lerociclib) orally (once daily) in combination with fulvestrant.
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Drug: G1T38
Other Name: lerociclib Drug: Fulvestrant Other Name: Faslodex |
Experimental: Twice-Daily G1T38 Dosing
G1T38 (lerociclib) orally (twice daily) in combination with fulvestrant.
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Drug: G1T38
Other Name: lerociclib Drug: Fulvestrant Other Name: Faslodex |
- Dose Limiting Toxicity [ Time Frame: Week 1 Day 1-Week 5 Day 1 ]
- Recommended Phase 2 dose [ Time Frame: 14 months ]
- Recommended Phase 2 dose interval [ Time Frame: 14 months ]Twice-Daily or Once-Daily dosing
- Number of Treatment Related Adverse Event, including Abnormal Laboratory Events [ Time Frame: 36 months ]All AEs, including clinical laboratory, vitals signs, physical examinations and ECGs will be analyzed in all patients receiving study drug from the signing of the informed consent until 30 days after the last dose of study medication up to 36 months
- Tumor response based on RECIST, Version 1.1 [ Time Frame: 30 months ]
- Pharmacokinetics of G1T38, Fulvestrant, and Goserelin: Maximum Plasma Concentration (Cmax) [ Time Frame: Week 1 Day 1-Week 9 Day 1 ]
- Pharmacokinetics of G1T38, Fulvestrant, and Goserelin: Area under Curve - plasma concentration (AUC) [ Time Frame: Week 1 Day 1-Week 9 Day 1 ]
- Pharmacokinetics of G1T38, Fulvestrant, and Goserelin: Plasma: terminal half life (T1/2) [ Time Frame: Week 1 Day 1-Week 9 Day 1 ]
- Pharmacokinetics of G1T38, Fulvestrant, and Goserelin: Plasma - Volume of distribution [ Time Frame: Week 1 Day 1-Week 9 Day 1 ]
- Progression free survival (PFS) [ Time Frame: 36 months ]
- Overall survival (OS) [ Time Frame: 48 months ]

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.
Ages Eligible for Study: | 18 Years and older (Adult, Older Adult) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | No |
Inclusion Criteria:
- Confirmed diagnosis of HR-positive, HER2-negative breast cancer, not amenable to curative therapy
- Pre- or perimenopausal women can be enrolled if amenable to be treated with goserelin
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Patients must satisfy 1 of the following criteria for prior therapy:
- Progressed during treatment or within 12 months of completion of adjuvant therapy with an aromatase inhibitor or tamoxifen
- Progressed during treatment or within 2 months after the end of prior aromatase inhibitor therapy for advanced/metastatic breast cancer, or prior endocrine therapy for advanced/metastatic breast cancer
- Received ≤ 2 chemotherapy regimens (Part 1) or ≤ 1 chemotherapy regimen (Part 2) for advanced/metastatic disease
- For Part 1, evaluable or measurable disease (bone only disease eligible for Part 1 only)
- For Part 2, measurable disease as defined by RECIST, Version 1.1
- ECOG performance status 0 to 1
- Adequate organ function
Exclusion Criteria:
- For Part 1, prior treatment with fulvestrant
- For Part 2, prior treatment with any CDK inhibitor or fulvestrant
- Active uncontrolled/symptomatic CNS metastases, carcinomatous meningitis, or leptomeningeal disease
- Chemotherapy within 21 days of first G1T38 dose
- Investigational drug within 28 days of first G1T38 dose
- Concurrent radiotherapy, radiotherapy within 14 days of first G1T38 dose, previous radiotherapy to the target lesion sites, or prior radiotherapy to > 25% of bone marrow
- Prior hematopoietic stem cell or bone marrow transplantation

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02983071
Bulgaria | |
MHAT for Womens Health - Nadezhda OOD | |
Sofia, Bulgaria, 1330 | |
Special Hospital For Active Treatment In Oncology | |
Sofia, Bulgaria, 1756 | |
Georgia | |
ARENSIA Exploratory Medicine LLC | |
Tbilisi, Georgia, 0112 | |
Moldova, Republic of | |
The Institute of Oncology | |
Chisinau, Moldova, Republic of, 2025 | |
United Kingdom | |
Cambridge University | |
Cambridge, United Kingdom, CB2 0QQ | |
University College London Hospital (UCLH) | |
London, United Kingdom, NW1 2BU | |
Sarah Cannon Research Institute | |
London, United Kingdom, W1G 6AD | |
The Christie NHS Foundation | |
Manchester, United Kingdom, M20 4BX |
Study Director: | Clinical Contact | G1 Therapeutics, Inc. |
Responsible Party: | G1 Therapeutics, Inc. |
ClinicalTrials.gov Identifier: | NCT02983071 |
Other Study ID Numbers: |
G1T38-02 2016-001485-29 ( EudraCT Number ) |
First Posted: | December 6, 2016 Key Record Dates |
Last Update Posted: | February 15, 2023 |
Last Verified: | February 2023 |
Breast Cancer CDK 4/6 Inhibitor HER2-Negative HR-Positive |
HR+ HER2- HER2 -ve HER2 +ve |
Breast Neoplasms Carcinoma, Ductal Carcinoma, Ductal, Breast Neoplasms by Site Neoplasms Breast Diseases Skin Diseases Adenocarcinoma Carcinoma Neoplasms, Glandular and Epithelial |
Neoplasms by Histologic Type Neoplasms, Ductal, Lobular, and Medullary Fulvestrant Antineoplastic Agents, Hormonal Antineoplastic Agents Estrogen Receptor Antagonists Estrogen Antagonists Hormone Antagonists Hormones, Hormone Substitutes, and Hormone Antagonists Physiological Effects of Drugs |