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Novel T-DM1 Prolongs Remission in Metastatic Breast Cancer: A New “Smart Bomb”

August 2012 Vol 5, No 5, Special Issue ASCO 2012 Payers' Perspective - Breast Cancer

Chicago, IL—The media darling at ASCO 2012 was a novel agent some called a “smart bomb,” because of its highly targeted and potent effect that spares surrounding healthy tissue.

Trastuzumab emtansine, better known as T-DM1, the antibody-drug conjugate linking trastuzumab to a cytotoxic agent, delivers its punch directly into the tumor of patients with HER2-positive metastatic breast cancer, and this agent is associated with little toxicity. T-DM1 is one of an entirely new class of agents that could have a major impact on the disease.

Early results from EMILIA, an international phase 3 clinical trial presented at the meeting’s plenary session, showed an increase of approximately 30% in progression-free survival (PFS) with T-DM1 compared with a standard treatment regimen.

“For patients facing metastatic breast cancer, this is a breakthrough,” said lead author Kimberly L. Blackwell, MD, of Duke Cancer Institute at Duke University, Winston-Salem, NC.

Louis Weiner, MD, Director, George­town-Lombardi Cancer Center in Washington, DC, the invited discussant for the study, commented, “Stated simply, T-DM1 really works in this patient population. It is an important new weapon in the therapeutic armamentarium for breast cancer.”

The EMILIA Study
EMILIA included 991 HER2-positive patients who had locally advanced or metastatic breast cancer and who had previously received a taxane and trastuzumab. Patients were randomized to receive intravenous T-DM1 or capecitabine plus lapatinib (XL) every 3 weeks, until progression.

The median PFS for the T-DM1 arm was 9.6 months compared with 6.4 months for XL, representing a 35% reduction in the risk of progression (P <.001), Dr Blackwell reported.

Median overall survival (OS) was not reached with T-DM1 and was 23.3 months with XL, for a 38% reduction in mortality risk (hazard ratio, 0.621; 95% confidence interval, 0.475-0.813; P <.005). This result, however, did not meet the prespecified threshold for statistical significance for this end point at the first analysis. Never­theless, after 2 years, 65.4% of the patients receiving T-DM1 were alive compared with only 47.5% of those receiving the XL regimen.

Dr Weiner predicted that a significant improvement in OS will eventually be observed, and this will be “particularly notable, since effective palliative treatment has rarely been associated with improved survival in the metastatic setting.”

Dose reductions were required for 16.3% of the patients receiving T-DM1 compared with 53.4% of those in the capecitabine arm and 27.3% in the lapatinib arm. Diarrhea, vomiting, hand-foot syndrome, and alopecia were reported with the chemotherapy regimen but not with T-DM1.

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Last modified: August 30, 2021