Tucatinib Combination in HER2-Positive Metastatic Breast Cancer: HER2CLIMB Trial

On December 11, 2019, Rashmi K. Murthy and colleagues published the results of the HER2CLIMB Phase 2 clinical trial in The New England Journal of Medicine. The study evaluated the efficacy and safety of Tucatinib, an oral HER2-specific tyrosine kinase inhibitor, in combination with Trastuzumab and Capecitabine for patients with pretreated HER2-positive metastatic breast cancer.

Study Design: HER2CLIMB Trial

The trial randomized 612 patients with pretreated HER2-positive metastatic breast cancer in a 2:1 ratio:

1. Tucatinib Group (N=410): Tucatinib (300 mg twice daily) + Trastuzumab + Capecitabine.
2. Placebo Group (N=202): Placebo + Trastuzumab + Capecitabine.

A unique feature of this trial was the inclusion of patients with stable or active/progressing brain metastases.

Key Survival Results

Total Population

• Median Progression-Free Survival (PFS): 7.8 months for the Tucatinib group vs. 5.6 months for the placebo group (Hazard Ratio [HR] = 0.54).
• 1-Year PFS Rate: 33.1% (Tucatinib) vs. 12.3% (Placebo).
• Median Overall Survival (OS): 21.9 months (Tucatinib) vs. 17.4 months (Placebo) (HR = 0.66).

Patients with Brain Metastases

• Median PFS: 7.6 months (Tucatinib) vs. 5.4 months (Placebo).
• Risk Reduction: The addition of Tucatinib reduced the risk of disease progression or death by 52% in patients with brain metastases.

Safety Profile

The incidence of Grade 3 or higher adverse events was 55.2% in the Tucatinib group and 48.7% in the placebo group. Common side effects in the Tucatinib group included diarrhea (80.9%), palmar-plantar erythrodysesthesia (hand-foot syndrome, 63.4%), and nausea (58.4%). Most were manageable with supportive care or dose modifications.

Conclusion

The HER2CLIMB trial results establish that the combination of Tucatinib, Trastuzumab, and Capecitabine significantly improves both progression-free and overall survival in patients with pretreated HER2-positive metastatic breast cancer, including those with brain metastases, providing a vital new treatment option for this population.

Source: The New England Journal of Medicine - HER2CLIMB Trial Results

#BreastCancer #HER2Positive #Tucatinib #BrainMetastases #HER2CLIMB #CancerResearch

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