Phase 3 Trial Investigates T-DM1 and Pertuzumab in HER2+ Breast Cancer

Julie Gralow, MD, the clinical director of Breast Medical Oncology at the Seattle Cancer Care Alliance, professor of Medical Oncology at the University of Washington School of Medicine, and professor of the Clinical Research Division at the Fred Hutchinson Cancer Research Center, discusses the primary analysis of trastuzumab emtansine (T-DM1; Kadcyla) plus pertuzumab (Perjeta) versus trastuzumab (Herceptin), pertuzumab, and taxane, after anthracyclines as adjuvant therapy in patients with high-risk HER2-positive early breast cancer in the of the KAITLIN study (NCT01966471).

At the 2020 American Society of Clinical Oncology Virtual Meeting, the trial showed that there was no difference between the 2 regimens. The T-DM1 and pertuzumab group did not do better than those receiving classic chemotherapy as well, according to Gralow. During the chemotherapy phase, the adverse events (AEs) and quality of life was better with T-DMI and pertuzumab. After patients were done with chemotherapy and completed a year of treatment, the T-DM1 arm had more patients dropping out than the arm receiving trastuzumab, pertuzumab, and taxane.

Patients who didn’t complete therapy could cross over to trastuzumab monotherapy or trastuzumab and pertuzumab. Gralow thinks that this allowance of crossing over is interesting because when giving chemotherapy, T-DM1 and pertuzumab is better; when patients are only on trastuzumab and pertuzumab portion for the year-long therapy, T-DM1 had more AEs. Gralow says it’s a reasonable regimen, although it didn’t meet the primary end point.

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