Trastuzumab Deruxtecan in Previously Treated HER2-Low Advanced Breast Cancer

Shanu Modi1, William Jacot1, Toshinari Yamashita1

  • 1From the Memorial Sloan Kettering Cancer Center, New York (S.M.); Institut du Cancer de Montpellier, Université Montpellier, INSERM Unité 1194, Montpellier (W.J.), and Institut Curie, Université Paris Cité, Paris (J.-Y.P.) - both in France; Kanagawa Cancer Center, Yokohama (T.Y.), Kyushu Cancer Center, National Hospital Organization, Fukuoka (E.T.), Showa University Hospital, Tokyo (J.T.), and Tokai University School of Medicine, Isehara-shi (N.N.) - all in Japan; Yonsei Cancer Center, Yonsei University Health System (J. Sohn), Samsung Medical Center (Y.H.P.), Seoul National University Hospital, Cancer Research Institute, Seoul National University College of Medicine, Seoul National University (S.-A.I.), and Asan Medical Center, University of Ulsan College of Medicine (S.-B.K.), Seoul, Kyungpook National University Chilgok Hospital, Daegu (Y.S.C.), and the National Cancer Center, Goyang-si (K.S.L.) - all in South Korea; the Department of Medical Oncology, Hospital Clínic de Barcelona (M.V., A.P.), Translational Genomics and Targeted Therapies in Solid Tumors, Institut d'Investigacions Biomèdiques August Pi i Sunyer (A.P.), the Department of Medicine, University of Barcelona (A.P.), the Breast Cancer Unit, Institute of Oncology (IOB)-Quirón Salud (A.P.), Institut Catala d'Oncologia l'Hospitalet-Hospital Duran i Reynals (M.G.-G.), and Vall d'Hebron University Hospital, Vall d'Hebron Institute of Oncology (C.S.) - all in Barcelona; the University of Texas M.D. Anderson Cancer Center, Houston (N.T.U.); Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing (B.X.), Zhejiang Cancer Hospital, Hangzhou (X.W.), the First Hospital of Jilin University, Changchun (W.L.), Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou (Q.L.), West China Hospital, Sichuan University, Chengdu (T.L.), and Liaoning Cancer Hospital and Institute, Shenyang (T.S.) - all in China; the Cleveland Clinic Foundation, Cleveland (H.C.F.M.); the University of California, San Francisco, Helen Diller Family Comprehensive Cancer Center, San Francisco (H.S.R.); Rabin Medical Center, Petah Tikva, Tel Aviv University, Tel Aviv, Israel (R.Y.); Alexandra Regional General Hospital, Athens (F.Z.); Institut Jules Bordet, Brussels (A.G.); Queen Mary University of London, London (P.S.), and Edinburgh Cancer Centre, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh (D.A.C.) - both in the United Kingdom; Daiichi Sankyo, Basking Ridge, NJ (D.G., L.Y., Y.W., J. Singh, P.V., G.M.); and the Breast Center, Department of Obstetrics and Gynecology, and Comprehensive Cancer Center Munich, Ludwig Maximilian University Hospital, Munich, Germany (N.H.).

Abstract

Insights

Trastuzumab deruxtecan significantly improved progression-free and overall survival for patients with HER2-low metastatic breast cancer. This targeted therapy offers a new option for patients previously lacking effective treatments.

Area of Science:

  • Oncology
  • Medical Research
  • Clinical Trials

Background:

  • A significant subset of breast cancers exhibit low levels of human epidermal growth factor receptor 2 (HER2), termed HER2-low.
  • Existing HER2-directed therapies have shown limited efficacy in HER2-low metastatic breast cancer patients.
  • HER2-low breast cancers represent a distinct subtype requiring targeted therapeutic strategies.

Purpose of the Study:

  • To evaluate the efficacy and safety of trastuzumab deruxtecan in patients with HER2-low metastatic breast cancer.
  • To compare trastuzumab deruxtecan against physician's choice chemotherapy in a pre-treated patient population.
  • To assess progression-free survival (PFS) and overall survival (OS) as primary and secondary endpoints.

Main Methods:

  • A phase 3, randomized trial enrolled patients with HER2-low metastatic breast cancer who had received prior chemotherapy.
  • Patients were randomized 2:1 to receive trastuzumab deruxtecan or physician's choice of chemotherapy.
  • HER2-low status was defined by immunohistochemical scores of 1+ or 2+ with negative in situ hybridization.

Main Results:

  • Trastuzumab deruxtecan demonstrated significantly longer median progression-free survival (10.1 months vs. 5.4 months) in the hormone receptor-positive cohort.
  • Overall survival was also significantly improved with trastuzumab deruxtecan (23.9 months vs. 17.5 months) in the hormone receptor-positive cohort.
  • Similar significant improvements in PFS and OS were observed across all patients, irrespective of hormone receptor status.

Conclusions:

  • Trastuzumab deruxtecan significantly enhances progression-free and overall survival compared to chemotherapy in HER2-low metastatic breast cancer.
  • This finding establishes trastuzumab deruxtecan as a new standard of care for this patient population.
  • The study highlights the importance of targeting HER2-low breast cancer with specific therapeutic agents.

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