The Australian Therapeutic Goods Administration (TGA) has approved Seattle Genetics’ Tukysa (tucatinib), when given alongside trastuzumab and Xeloda (capecitabine), for the treatment of patients with advanced inoperable or metastatic HER2-positive breast cancer, who received at least one anti-HER2-based treatment for metastatic disease.
The approval also includes those in whom cancer has already spread to the brain (brain metastases). With this approval, Australia joins the list of countries, including the U.S., Canada, Switzerland, and Singapore, where Tukysa has been approved for the same indication under Project Orbis.
Project Orbis was created by the U.S. Food and Drug Administration‘s Oncology Center of Excellence to allow simultaneous submission and review of cancer medications among international regulatory partners.
“The rapid approval of concurrent global reviews under FDA’s Project Orbis for Tukysa will allow for accelerated market entry of this new best-in-class treatment to HER2-positive breast cancer patients in need,” Clay Siegall, PhD, CEO of Seattle Genetics, said in a press release. “As our company continues to expand globally, we look forward to bringing Tukysa to patients around the world.”
Tukysa is an oral small molecule that blocks the activity of HER2, a protein receptor that is known to promote the growth of certain types of breast cancer. The medication can also be used to treat patients with brain metastases, due to its ability to cross the blood-brain barrier — a semi-permeable barrier that protects the brain and spinal cord from the surrounding environment.
The TGA’s decision to approve the combination therapy for this indication was based on data from the Phase 2 HER2CLIMB trial (NCT02614794).
HER2CLIMB was designed to investigate if adding Tukysa to a combination therapy of trastuzumab and Xeloda would be beneficial to prolong the time patients with HER2-positive breast cancer lived without the disease worsening.
The study enrolled a total of 612 patients with locally inoperable or metastatic disease, who had previously been treated with trastuzumab (sold under the brand name Herceptin, among others), Perjeta (pertuzumab), and/or Kadcycla (ado-trastuzumab emtansine).
During the trial, patients were randomly assigned to receive a combination therapy containing Tukysa or a placebo, given alongside trastuzumab and Xeloda.
The combination therapy containing Tukysa extended the time patients lived without disease worsening from a median of 5.6 months to 7.8 months, lowering the risk of disease progression or death by 46%, according to data published in the New England Journal of Medicine.
In the subset of patients with brain metastases, which made up 48% of the participants, the combination therapy containing Tukysa prolonged the time they lived without disease progression from a median of 5.4 to 7.6 months, reducing the risk of death or disease worsening by 52%.
In all patients in the trial, the Tukysa combo therapy was also found to increase their overall survival from a median of 17.4 to 21.9 months, lowering the risk of death by 34%.
The combination therapy was deemed safe and generally well-tolerated by patients. Treatment-related deaths or discontinuations were rare in both treatment groups.
Seattle Genetics is now planning to explore the therapeutic potential of Tukysa in patients at an earlier stage of HER2-positive breast cancer, and for other types of solid tumors.
The company is also awaiting feedback from European regulators that are currently reviewing an application for the approval of the triple combo therapy to treat advanced HER2-positive breast cancer.