Seagen Inc. announced that the U.S. Food and Drug Administration (FDA) has granted accelerated approval to TUKYSA (tucatinib) in combination with trastuzumab for adult patients with RAS wild-type, HER2-positive unresectable or metastatic colorectal cancer that has progressed following treatment with fluoropyrimidine-, oxaliplatin- and irinotecan-based chemotherapy.
TUKYSA is approved under the FDA’s Accelerated Approval Program based on tumor response rate and durability of response from the phase 2 MOUNTAINEER clinical trial. Continued approval for this indication may be contingent upon verification and description of clinical benefit in confirmatory trials. This is the first FDA-approved treatment in HER2-positive metastatic colorectal cancer. The FDA previously granted Breakthrough Therapy Designation and Priority Review for TUKYSA in this setting.
Results from the MOUNTAINEER trial showed a 38% overall response rate (ORR) (95% Confidence Interval [CI]: 28, 49) per blinded independent central review (BICR) in the patients who received TUKYSA in combination with trastuzumab (N=84 with a median age of 55.0 years [range: 24 to 77]). Complete responses were observed in 3.6% of patients (n=3), and partial responses were observed in 35% of patients (n=29). The median duration of response (DOR) per BICR was 12.4 months (95% CI: 8.5, 20.5). At study entry, 64% and 70% of these patients had liver or lung metastases, respectively.
The Prescribing Information for TUKYSA includes warnings and precautions for diarrhea, hepatotoxicity and embryo-fetal toxicity, some of which may be severe or fatal. In MOUNTAINEER, serious adverse reactions occurred in 22% of patients; the most common (in ≥2% of patients) were intestinal obstruction (7%), urinary tract infection (3.5%), pneumonia, abdominal pain and rectal perforation (2.3% each). The most common adverse reactions (≥20%) in patients treated with TUKYSA and trastuzumab were diarrhea, fatigue, rash, nausea, abdominal pain, infusion-related reactions and pyrexia. Adverse reactions leading to permanent discontinuation of TUKYSA occurred in 6% of patients; the most common (in ≥2% of patients) was increased alanine aminotransferase (ALT) (2.3%). Please see additional Important Safety Information below.
