Clinical Report: 2026 ASCO Breast Cancer Highlights: HER2CLIMB-05

Overview

Harold Burstein, MD, PhD, and Adrienne Waks, MD, discuss HER2CLIMB-05 and its relevance to treatment of HER2-positive metastatic breast cancer. The trial evaluated tucatinib added to trastuzumab and pertuzumab as first-line maintenance after taxane-based induction; the primary analysis found significantly longer investigator-assessed progression-free survival with tucatinib.

Background

HER2CLIMB-05 addresses treatment after initial taxane-based induction with trastuzumab and pertuzumab in patients with HER2-positive metastatic breast cancer who have no evidence of progression. The phase III study compared continued trastuzumab and pertuzumab with or without tucatinib during maintenance. The supplied 2026 guidance context describes HER2-targeted regimens as the basis of first-line systemic therapy and lists tucatinib, trastuzumab, and capecitabine as an option in subsequent lines. The FDA approved tucatinib with trastuzumab and pertuzumab as maintenance therapy after induction on October 7, 2026, based on HER2CLIMB-05.

Data Highlights

Key Findings

• HER2CLIMB-05 studied tucatinib or placebo added to trastuzumab and pertuzumab as first-line maintenance after 4–8 cycles of taxane-based induction.
• Eligible patients had no evidence of disease progression after induction, according to the supplied trial summary.
• At primary analysis, tucatinib significantly improved investigator-assessed progression-free survival, with an 8.6-month absolute benefit (hazard ratio 0.641; P < .0001).
• The reported safety profile was consistent with known effects of the agents.
• In the tucatinib arm, grade 3 or higher diarrhea occurred in 6.1%; grade 3 or higher ALT and AST elevations occurred in 13.5% and 7.1%, respectively.
• The supplied web research context reports FDA approval of tucatinib with trastuzumab and pertuzumab for maintenance after induction on October 7, 2026, based on HER2CLIMB-05.

Clinical Implications

The trial evaluates a maintenance option for patients with HER2-positive metastatic breast cancer who have no progression after taxane-based induction with trastuzumab and pertuzumab. The supplied context reports FDA approval of the tucatinib-containing maintenance regimen and identifies diarrhea and transaminase elevations among the reported grade 3 or higher adverse events.

Conclusion

HER2CLIMB-05 found significantly longer investigator-assessed progression-free survival when tucatinib was added to trastuzumab and pertuzumab as first-line maintenance. The supplied context also reports FDA approval of this maintenance combination after induction.

Related Resources & Content

1. The ASCO Post, 2026 — Adding Tucatinib to First-Line Maintenance Therapy Delays Disease Progression in HER2-Positive Metastatic Breast Cancer
2. Guideline Central, 2026 — ASCO Systemic Therapy for Advanced Human Epidermal Growth Factor Receptor 2–Positive Breast Cancer Guideline Summary
3. The ASCO Post — SABCS 2025: High-Level Review of Select Data
4. The ASCO Post — SABCS 2025: High-Level Review of Select Data
5. The ASCO Post — SABCS 2025: High-Level Review of Select Data
6. The ASCO Post — SABCS 2025: High-Level Review of Select Data
7. Adding Tucatinib to First-Line Maintenance Therapy Delays Disease Progression in HER2-Positive Metastatic Breast Cancer
8. ASCO Systemic Therapy for Advanced Human Epidermal Growth Factor Receptor 2–Positive Breast Cancer Guideline Summary
9. ASCO Systemic Therapy for Advanced Human Epidermal Growth Factor Receptor 2–Positive Breast Cancer Guideline Summary - Guideline Central
10. Adding Tucatinib to First-Line Maintenance Therapy Delays Disease Progression in HER2-Positive Metastatic Breast Cancer - The ASCO Post
11. Tucatinib and trastuzumab emtansine for patients with previously treated HER2-positive locally advanced and metastatic breast cancer: primary analysis of the randomized phase III trial HER2CLIMB-02 - PubMed