The FDA has approved Phesgo (pertuzumab + trastuzumab + hyaluronidase–zzxf), from Genentech/Roche, for injection under the skin to treat adult patients with HER2-positive breast cancer that has spread to other parts of the body, and for treatment of adult patients with early HER2-positive breast cancer. Patients should be selected based on an FDA-approved companion diagnostic test. Phesgo contains a fixed-dose combination of pertuzumab and trastuzumab with hyaluronidase for injection under the skin. The therapeutic components in Phesgo are the same as those in FDA-approved intravenous (IV) pertuzumab and IV trastuzumab.
The FDA’s approval was based on the results of a non-inferiority study in patients with HER2-positive early breast cancer, which demonstrated Phesgo had comparable efficacy and safety as IV pertuzumab and IV trastuzumab, except for administration-related reactions, which were higher with Phesgo due to the subcutaneous route of administration. The most common side effects for patients taking Phesgo were alopecia (hair loss), nausea, diarrhea, anemia (reduced number of red blood cells) and asthenia (lack of energy).