American biotechnology company Seagen (formerly Seattle Genetics) has received accelerated approval from the US Food and Drug Administration (FDA) for the company’s oral drug Tukysa (tucatinib) in combination with trastuzumab.

Tukysa in combination with trastuzumab is indicated for the treatment of adult patients with RASwild-type, HER2-positive unresectable or metastatic colorectal cancer, which has advanced following fluoropyrimidine-, oxaliplatin- and irinotecan-based chemotherapy treatment.

The clearance marks the first FDA-approved treatment in HER2-positive metastatic colorectal cancer.

The FDA has granted accelerated approval based on the tumor response rate and durability of response from the phase 2 MOUNTAINEER clinical trial.

John Strickler — MOUNTAINEER trial lead investigator said: “Historically, patients with HER2-positive metastatic colorectal cancer who have progressed following frontline therapy have had poor outcomes.

“The FDA approval of a chemotherapy-free combination regimen that specifically targets HER2 is great news for these patients.”

In the phase 2 MOUNTAINEER study of 84 patients, Tukysa in combination with trastuzumab demonstrated a 38% overall response rate while three patients experienced complete responses and 29 patients experienced partial responses.

Patients received Tukysa (300 mg) twice per day orally with trastuzumab administered at a loading dose of 8 mg/kg intravenously, then 6 mg/kg every three weeks thereafter until disease progression or unacceptable toxicity.

The continued approval for RASwild-type, HER2-positive unresectable or metastatic colorectal cancer may be contingent upon verification and description of clinical benefit in confirmatory trials.

Merck secured exclusive rights through $4.4bn worth oncology deals with Seattle Genetics in 2020 to market Tukysa in Asia, the Middle East, and Latin America and other regions outside of the US, Canada, and Europe.

In April 2020, the FDA approved Tukysa in combination with trastuzumab and capecitabine for the treatment of adult patients with advanced unresectable or metastatic HER2-positive breast cancer.

Seagen, citing The American Cancer Society, said around 153,000 people will be diagnosed with colorectal cancer in the US in 2023.

  Colorectal cancer, John Strickler, Merck, Metastatic colorectal cancer, Oncology, Seattle Genetics, trastuzumab, Tucatinib, TUKYSA, US FDA, US Food and Drug Administration, USA