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

While future confirmatory studies will be important, especially to elucidate the mechanisms of tumor control with T-DM1, he maintained that “the very clean design and institution of this study, coupled with the compelling results, make it unlikely that additional studies will fail to confirm these important findings.” 

Dr. Weiner predicted that a statistically significant improvement in overall survival will eventually be observed, which he said would be “particularly notable since effective palliative treatment has rarely been associated with improved survival in the metastatic setting.”

Looking Ahead

Looking to the future, Dr. Weiner predicted that pairing T-DM1 with different classes of agents will broaden the range of treatment efficacy. “And this is happening,” he reported, noting that 17 T-DM1–based clinical trials are accruing or in progress, some with chemotherapy and others with targeted agents.

“Needless to say, T-DM1 merits evaluation for previously untreated HER2-overexpressing metastatic breast cancer and ultimately may find utility in adjuvant and neoadjuvant management, and perhaps in other HER2-overexpresssing cancers,” he added. “Such trials are planned or in progress.” ■

Disclosure: Dr. Weiner reported serving in a consulting or advisory role for Abbott Laboratories, Celldex, Johnson and Johnson, Merrimack, Samsung Advanced Institute of Technology, Symphogen; owning stock in Celldex and Merrimack; receiving honoraria from Bristol-Myers Squibb; and receiving research funding from Samsung Advanced Institute of technology.