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May 29, 2026

Capivasertib plus fulvestrant in Chinese patients with HR+/HER2− advanced breast cancer: Interim analysis of CAPItrue.

Key Points

This research aims to evaluate the efficacy and safety of capivasertib plus fulvestrant in Chinese patients with advanced breast cancer after prior treatment failure.
Conducted an interim analysis in an ongoing phase IIIb study (CAPItrue) of capivasertib plus fulvestrant in 195 Chinese patients with HR+/HER2− advanced breast cancer.
All patients received oral capivasertib (400 mg BID, 4 days on, 3 days off) and intramuscular fulvestrant after progression on endocrine therapy with or without cdk4/6 inhibitors.
Evaluated baseline characteristics, biomarker profiles, and preliminary objective response rate (ORR) after at least 4 months of follow-up.
Overall ORR was 35.6% (37/104), with a 43.1% ORR (25/58) in the PIK3CA/AKT1/PTEN-altered group.
At a median follow-up of 4.1 months, 92.8% of patients experienced at least one adverse event; 34.9% had grade ≥3 adverse events.
No new safety signals were identified, with a similar safety profile in both overall and altered groups.

Abstract

1088 Background: After disease progression on cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) plus endocrine therapy (ET), patients (pts) with HR+/HER2- advanced breast cancer (ABC) face limited treatment options and poor prognosis, particularly those with PI3K/AKT pathway tumor alterations, which are major drivers of disease progression and treatment resistance mediated centrally by AKT. Targeting the PI3K/AKT pathway represents a mechanism-driven precision strategy to overcome CDK4/6i/ET resistance, with potential to maximize ET benefit and delay subsequent chemotherapy. In the phase III CAPItello-291 trial, capivasertib (CAPI) plus fulvestrant (FUL) improved progression free survival (7.3 vs 3.1 months, HR 0.50) versus placebo plus FUL in pts with PIK3CA/AKT1/PTEN -altered tumors. CAPItrue (NCT06635447) is an ongoing phase IIIb study of CAPI plus FUL in Chinese pts with HR+/HER2- ABC progressing on ET, with a focus on PIK3CA/AKT1/PTEN-altered disease, aiming to inform precision 2 nd line treatment following CDK4/6i progression. Methods: CAPItrue enrolled Chinese pts with HR+/HER2- ABC progressing on ET±CDK4/6i. All pts received oral CAPI (400 mg BID, 4 days on, 3 days off) and intramuscular FUL. This pre-specified interim analysis was performed in the cohort (C1) without prior FUL (conducted after the last C1 pt received ≥1 dose of study treatment). Baseline characteristics, biomarker profiles, preliminary efficacy (interim objective response rate ORR was evaluated in pts with ≥4 months of follow-up) and safety were summarized. Results: By Aug 20, 2025, 195 pts were enrolled in C1 and received study treatment. PIK3CA/AKT1/PTEN alterations were detected in 115 (59.0%) pts (altered group). The median age was 55.0 yrs; 64.1% were post-menopausal. Prior therapy for ABC included: 75.4%/8.7% 1/2 prior lines of ET; 65.1% CDK4/6i, 17.9% chemotherapy. The altered group showed similar characteristics. In patients with ≥4 months of follow-up, ORR was 35.6% overall (37/104, 1 complete and 36 partial responses PR) and 43.1% in the altered group (25/58, 25 PR). Overall, at a median follow-up of 4.1 months,92.8% had ≥1 adverse event (AE); 88.7% had AEs possibly related to CAPI; and 34.9%/11.8% had grade ≥3/serious AEs (SAE). A similar safety profile was seen in the altered group (any AE: 92.2%, grade ≥3 AE: 30.4%, SAE: 11.3%). No new safety signal was observed. Conclusions: In Chinese pts with PIK3CA/AKT1/PTEN -altered HR+/HER2- ABC previously treated with ET±CDK4/6i, CAPI plus FUL showed encouraging preliminary efficacy and safety. Follow-up is ongoing. Clinical trial information: NCT06635447 .

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