A Phase 1/2 interventional study of GVV858 and Fulvestrant in Advanced HR+/HER2- Breast Cancer, Advanced CCNE1-amplified Solid Tumors and Metastatic Castration-resistant Prostate Cancer, sponsored by Novartis Pharmaceuticals. Recruiting at 15 sites in 10 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-07-30.
Sponsored by Novartis Pharmaceuticals · Phase 1/2, Interventional, and Treatment
Phase I: Characterize safety and tolerability of GVV858 as a single agent and in combination with fulvestrant or letrozole. Identify dose range for optimization/recommended dose for further clinical evaluation.
Phase II: Further characterize the safety and tolerability of GVV858 in combination with fulvestrant in patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer.
This is a first-in-human, open-label, phase I/II, multi-center study consisting of a GVV858 single agent treatment arm in patients with advanced HR+/HER2- breast cancer, other advanced solid tumors harboring CCNE1 amplification, and metastatic castration-resistant prostate cancer, and a combination treatment arm of GVV858 with fulvestrant or letrozole in patients with advanced HR+/HER2- breast cancer. Single agent escalation may be followed by an expansion part stratified by disease indication. The escalation of the fulvestrant combination arm may continue into a randomized, open label, Phase II with optional dose optimization in advanced HR+/HER2- breast cancer patients.
12,544 studies on the registry are indexed under Breast Neoplasms; 2,892 are open to participants now.
This study's planned enrollment of 205 is above the median of 72 across 9,303 interventional studies indexed under Breast Neoplasms.
Browse Breast Neoplasms studies →Novartis Pharmaceuticals is the lead sponsor of 2,673 studies on the registry; 228 are open to participants now.
Of its 576 completed or terminated interventional studies of FDA-regulated products, 431 (75%) have results posted.
Counted across the registry records on this site, refreshed daily.
Phase I (patients with one of the following cancers, from whom no standard therapy is available or appropriate in the judgment of the investigator):
Phase II:
HR+/HER2- aBC with disease progression on or after an endocrine therapy in combination, with a CDK4/6 inhibitor for advanced disease with no more than 2 lines of endocrine therapy and no prior cytotoxic chemotherapy or antibody-drug-conjugate for advanced disease.
- Measurable disease as determined by RECIST v1.1.
Exclusion Criteria:
Other protocol-defined inclusion/exclusion criteria may apply.
Phase I
Drug: GVV858
Phase I
Drug: GVV858 · Drug: Fulvestrant
Phase I
Drug: GVV858 · Drug: Letrozole
Phase II, recommended dose regimen 1
Drug: GVV858 · Drug: Fulvestrant
Phase II, recommended dose regimen 2, optional dose optimization
Drug: GVV858 · Drug: Fulvestrant
Experimental
Approved medication
Also known as: Faslodex
Approved medication
Also known as: Femara
Phase I: Incidence and severity of dose-limiting toxicities (DLTs)
Number of participants with DLTs. A DLT is defined as an adverse event or abnormal laboratory value of Common Terminology Criteria for Adverse Events (CTCAE) grade 3 or higher, unless clearly and inconvertibly assessed as due to disease progression, inter-current illness/injury, concomitant medications, or extraneous causes, that occurs within the first 28 days of treatment in the Phase 1 part. Other clinically significant toxicities may be considered to be DLTs, even if not CTCAE grade 3 or higher.
Time frame: 28 days
Phase I and phase II: Incidence and severity of adverse events (AEs) and serious adverse events (SAEs)
Number of participants with AEs and SAEs, including changes in vital signs, electrocardiograms (ECGs) and laboratory values qualifying and reported as AEs.
Time frame: Up to approximately 2 years
Phase I and phase II: Frequency of dose interruptions, reductions and discontinuations
Number of participants with dose adjustments (reductions, interruption, or permanent discontinuation) as a measure of tolerability.
Time frame: Up to approximately 2 years
Phase I and phase II: Dose intensity
The dose intensity of each study drug is computed as the ratio of actual cumulative dose received and actual duration of exposure.
Time frame: Up to approximately 2 years
Phase I and II: Peak plasma concentration (Cmax) of GVV858
Pharmacokinetic (PK) parameters calculated based on GVV858 plasma concentrations.
Time frame: Cycle 1 Day 1 and/or Day 21: From pre-dose up to maximum 24 hours post dose. The duration of one cycle is 28 days.
Phase I and II: Time to reach peak plasma concentration (Tmax) of GVV858
PK parameters calculated based on GVV858 plasma concentrations.
Time frame: Cycle 1 Day 1 and/or Day 21: From pre-dose up to maximum 24 hours post dose. The duration of one cycle is 28 days.
Phase I and II: Area under the plasma concentration-time curve (AUC) of GVV858
PK parameters calculated based on GVV858 plasma concentrations.
Time frame: Cycle 1 Day 1 and/or Day 21: From pre-dose up to maximum 24 hours post dose. The duration of one cycle is 28 days.
Phase I and Phase II: Overall response rate (ORR)
Tumor response assessed by the investigator based on Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1), or Prostate Cancer Working Group 3 (PCWG3) criteria including PCWG3-modified RECIST v1.1. (only for patients with prostate cancer). ORR per RECIST v1.1 is defined as the proportion of patients with a best overall response of Complete response (CR) or Partial response (PR) according to RECIST v1.1 as per local review.
Time frame: Up to approximately 2 years
Phase I and Phase II: Best overall response (BOR)
Tumor response assessed by the investigator based on based on RECIST v1.1, or PCWG3 criteria including PCWG3-modified RECIST v1.1. (only for patients with prostate cancer). BOR per RECIST v1.1 is defined as the best overall confirmed response recorded from the start of the treatment until progressive disease (PD), death, start of new therapy, withdrawal of consent or end of study, whatever comes first.
Time frame: Up to approximately 2 years
Phase I and Phase II: Disease control rate (DCR)
Tumor response assessed by the investigator based on based on RECIST v1.1, or PCWG3 criteria including PCWG3-modified RECIST v1.1. (only for patients with prostate cancer). DCR per RECIST v1.1 is defined as the proportion of patients with a BOR of CR, PR, or Stable disease (SD) according to RECIST v1.1 as per local review.
Time frame: Up to approximately 2 years
Phase I and Phase II: Clinical benefit rate (CBR)
Tumor response assessed by the investigator based on based on RECIST v1.1, or PCWG3 criteria including PCWG3-modified RECIST v1.1. (only for patients with prostate cancer). CBR per RECIST v1.1 is defined as the proportion of patients with a BOR of CR, PR, or an overall lesion response of SD or Non-CR/Non-PD which lasts for at least 24 weeks according to RECIST v1.1 as per local review.
Time frame: Up to approximately 2 years
Phase I and Phase II: Progression free survival (PFS)
Tumor response assessed by the investigator based on based on RECIST v1.1, or PCWG3 criteria including PCWG3-modified RECIST v1.1. (only for patients with prostate cancer). PFS per RECIST 1.1 is defined as the time from the date of start of study treatment (phase I) or the date of randomization (Phase II) to the date of the first documented progression or death due to any cause.
Time frame: Up to approximately 2 years
Phase II: Duration of response (DOR)
Tumor response assessed by the investigator based on based on RECIST v1.1, or PCWG3 criteria including PCWG3-modified RECIST v1.1. (only for patients with prostate cancer). DOR per RECIST v1.1 is the time between the first documented response (CR or PR) and the date of progression by local review as applicable or death due to any cause.
Time frame: Up to approximately 2 years
Plan to share: Yes — Novartis is committed to sharing with qualified external researchers, access to patient-level data and supporting clinical documents from eligible studies. These requests are reviewed and approved by an independent review panel on the basis of scientific merit. All data provided is anonymized to respect the privacy of patients who have participated in the trial in line with applicable laws and regulations. This trial data availability is according to the criteria and process described on https://www.clinicalstudydatarequest.com/.
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