The Food and Drug Administration (FDA) has approved Phesgo™ (pertuzumab, trastuzumab, hyaluronidase-zzxf; Genentech), in combination with chemotherapy, for the treatment of early and metastatic HER2-positive breast cancer.

Phesgo is a fixed-dose combination of pertuzumab (Perjeta®) and trastuzumab (Herceptin®), HER2/neu receptor antagonists, and hyaluronidase, an endoglycosidase used to increase the dispersion and absorption of coadministered drugs via subcutaneous drug delivery. The product is indicated for:

  • Use in combination with chemotherapy as neoadjuvant treatment of patients with HER2-positive, locally advanced, inflammatory, or early stage breast cancer (either greater than 2cm in diameter or node positive) as part of a complete treatment regimen for early breast cancer.
  • Use in combination with chemotherapy as adjuvant treatment of patients with HER2-positive early breast cancer at high risk of recurrence.
  • Use in combination with docetaxel for treatment of patients with HER2– positive metastatic breast cancer (MBC) who have not received prior anti-HER2 therapy or chemotherapy for metastatic disease. 

Phesgo is administered subcutaneously (SC) into the thigh by a healthcare professional at either a treatment center or in a patient’s home. It is administered over approximately 8 minutes for the initial loading dose and approximately 5 minutes for each subsequent maintenance dose. In comparison, the administration of Perjeta and Herceptin via intravenous (IV) infusion is approximately 150 minutes for the loading dose and 60-150 minutes for subsequent maintenance infusions. 

The approval of Phesgo was based on data from previous studies conducted with IV pertuzumab and IV trastuzumab administered in combination, as well as an open-label phase 3 study (FeDeriCa) that compared the efficacy and safety of Phesgo SC to IV pertuzumab and trastuzumab plus chemotherapy in 500 adults with HER2-positive early breast cancer in the neoadjuvant/adjuvant setting. Results showed that Phesgo met the primary end point demonstrating noninferior levels of pertuzumab in the blood during a given dosing interval (Ctrough) compared with IV administration of pertuzumab. 

“The fixed-dose combination of trastuzumab and pertuzumab offers a simpler, faster and easier treatment experience for patients with HER2-positive breast cancer,” said Antoinette R. Tan, MD, MHSc, Chief of Breast Medical Oncology at Levine Cancer Institute, Atrium and an investigator of the FeDeriCa study. “This development is exciting because it makes the treatment process more efficient for patients, to be able to receive a drug subcutaneously instead of intravenously. A home administration protocol for this subcutaneous formulation is an area of current research and can be advantageous for patients and infusion centers, especially during the current pandemic.”

Additionally, data from the phase 2 PHranceSCa study showed that 85% of patients (n=136 out of 160) preferred Phesgo SC due to less time in the clinic and more comfortable administration compared with IV formulations of pertuzumab and trastuzumab.

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Phesgo is supplied in 15mL single-dose vials containing pertuzumab 1200mg, trastuzumab 600mg, and hyaluronidase 30,000 Units and 10mL single-dose vials containing pertuzumab 600mg, trastuzumab 600mg, and hyaluronidase 20,000 Units.

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