T-DM1 Shows Encouraging Results in Women With Advanced HER2-Positive Breast Cancer

Strategic Insights -

In a phase II study, the investigational antibody-drug conjugate, T-DM1, demonstrated promising results in women with advanced HER2-positive breast cancer who had received multiple prior medications. The study, conducted by Genentech, showed that T-DM1 shrank tumors in 33% of the participants, who had an average of seven previous treatments, including chemotherapy and other targeted therapies. The results, presented at the San Antonio Breast Cancer Symposium, indicate that T-DM1 may offer a new treatment option for women with HER2-positive breast cancer that has progressed after standard therapies.

Key Takeaways:

  • T-DM1 shrank tumors in 33% of participants, as assessed by independent review, in a single-arm phase II study.
  • Women in the study had received an average of seven prior treatments, including chemotherapy, trastuzumab, and lapatinib.
  • No new or unexpected safety signals were observed in the study.
  • 45% of women experienced a clinical benefit, defined as a complete or partial tumor response, or stable disease maintained for at least six months.
  • Adverse events were similar to those observed in previous trials of T-DM1, with fatigue and nausea being the most common side effects.
  • T-DM1 is a novel antibody-drug conjugate that combines the anti-cancer activity of the trastuzumab antibody with the targeted delivery of the cytotoxic DM1.
  • Genentech has initiated a phase III study, EMILIA, to evaluate T-DM1 in women with advanced HER2-positive breast cancer.

Statistics:

  • 33% of participants experienced a tumor shrinkage (objective response rate) in the study.
  • 45% of women experienced a clinical benefit (complete or partial tumor response, or stable disease maintainted for at least six months).
  • 5.5% of participants experienced severe thrombocytopenia (low platelet count) as a side effect.
  • 3.6% of participants experienced severe back pain as a side effect.
  • Fatigue (59.1%) and nausea (37.3%) were the most common adverse events.

Sources:

  • Genentech Press Release, "Genentech Announces Positive Results from Phase II Study of Trastuzumab-DM1 (T-DM1)" [Source: Genentech]
  • The San Antonio Breast Cancer Symposium, Abstract #710 [Source: San Antonio Breast Cancer Symposium]