NCT07666555 Fulvestrant PIK3CA mutation/HR-positive/HER2-negative Breast Cancer Clinical Landscape Report 2026: Design, Endpoints, Sponsor and Readout Outlook
Turn a newly registered trial into a decision-ready clinical landscape. This report examines NCT07666555 using PatSnap Clinical Trials MCP for protocol design and endpoint evidence, with Drug & Asset MCP and Company & Deal Intelligence MCP used as the companion asset and sponsor enrichment workflow. Explore PatSnap MCP Servers to reproduce the research sequence inside an AI workflow.
MCP evidence snapshot: 4 August 2026. Trial records, recruitment status and projected dates can change after the snapshot and should be rechecked before operational decisions.
Why NCT07666555 is a hot trial to watch
PIK3CA mutation/HR-positive/HER2-negative Breast Cancer is being segmented by mechanism, treatment setting, geography and endpoint architecture. NCT07666555 is notable because it evaluates Fulvestrant in a Phase 2 design sponsored by Fudan University. The main development question is whether the protocol can translate its rationale into a clinically interpretable and operationally credible readout.
Trial landscape snapshot
| Field | Indexed detail |
|---|---|
| Registration | NCT07666555 |
| Official title | A Phase II Clinical Study of the Efficacy and Safety of Culmerciclib Rechallenge in HR-positive, HER2-negative Breast Cancer Patients With Resistance to First-line Endocrine Therapy. |
| Phase / status | Phase 2 / Recruiting |
| Intervention | Fulvestrant |
| Sponsor | Fudan University |
| Geography | China |
| Enrollment | [object Object] |
| Primary endpoint | PFS |
| Endpoint time frame | Randomization until the first occurrence of disease progression or death from any cause, which ever occurs first, through the end of study (approximately 1 years) |
| Primary completion / readout proxy | [object Object] |
Protocol design and endpoint interpretation
To evaluate the efficacy and safety of Culmerciclib combined with fulvestrant compared with investigator-selected CDK4/6 inhibitors combined with fulvestrant in patients with HR-positive/HER2-negative breast cancer who have progressed after first-line endocrine therapy
Allocation is Randomized, masking is None (Open Label), and the intervention model is Parallel Assignment. Planned enrollment of [object Object] participants across China shapes statistical precision, execution risk and external validity. Interpretation should account for baseline risk, prior therapy, assessment schedule, missing-data handling and clinical relevance—not only statistical significance.
- PFS (Randomization until the first occurrence of disease progression or death from any cause, which ever occurs first, through the end of study (approximately 1 years)) — time to progressive disease (according to RECIST1.1)
Readout outlook and evidence gap
The current protocol points to [object Object] as the best available readout proxy. Because this is an active or newly posted study, a trial-specific result citation is not included until a normalized clinical-trial-result record becomes available. That gap is itself operationally important: teams should monitor first result indexing, conference abstracts, protocol amendments and changes to the primary-completion date.
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Asset and sponsor context
Drug & Asset MCP profile: Fulvestrant is indexed as No normalized modality returned, with target No normalized target returned, mechanism No normalized mechanism returned, and global highest development status No normalized global status returned.
Company & Deal Intelligence MCP profile: Fudan University is resolved to a normalized organization record in Shanghai Shi, China. The organization workflow adds identity, location, portfolio and partnering context where available.
The sponsor profile matters because scientific rationale alone does not determine development value. Manufacturing readiness, portfolio fit, geographic reach, partnering capacity and the ability to fund confirmatory development can determine whether a positive signal becomes a competitive asset.
White space around this program
- Sharper patient selection: prospective biomarker or phenotype definitions that identify who is most likely to benefit.
- Clinically interpretable endpoints: outcomes connecting activity with function, symptoms, survival or treatment burden.
- Comparator relevance: evidence against the most decision-relevant contemporary standard of care.
- Broader external validity: evidence across additional geographies, demographic groups and real-world settings.
- Operational differentiation: a development path that closes the readout gap without sacrificing safety or durability.
What to monitor next
Monitor recruitment, enrollment changes, protocol amendments, endpoint hierarchy, primary-completion timing, first result indexing, asset ownership and sponsor partnerships. A change in endpoint, population or ownership can alter the probability of success before a headline data release.
Bottom line
NCT07666555 provides a focused lens on PIK3CA mutation/HR-positive/HER2-negative Breast Cancer development. Its value will be determined by whether Fulvestrant can convert the current Phase 2 design into evidence that is clinically meaningful, operationally credible and differentiated from competing programs.
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