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Women with HER2-positive breast cancer will soon have a more convenient option for a widely used treatment, currently available only by infusion, as a result of FDA approval of the fixed-dose combination Phesgo.

Phesgo consists of pertuzumab (Perjeta), trastuzumab (Herceptin), and hyaluronidase-zzxf for subcutaneous injection. Initially administered along with chemotherapy, Phesgo maintenance treatment could continue at home with the assistance of a qualified healthcare professional.

"Currently, most patients with HER2-positive breast cancer receive trastuzumab and pertuzumab at infusion centers," Richard Pazdur, MD, of the FDA Office of Oncologic Diseases, said in a statement. "With a new administration route, Phesgo offers an outpatient option for patients to receive trastuzumab and pertuzumab."

"As part of the FDA's ongoing commitment to address the novel coronavirus pandemic, we continue to keep a strong focus on patients with cancer, who constitute a vulnerable population at risk of contracting the disease. At this critical time, we continue to expedite oncology product development. This application was approved about four months ahead of the FDA goal date."

Supporting data for the approval came from the FeDeriCa randomized trial comparing subcutaneous Phesgo with conventional intravenous infusion of pertuzumab and trastuzumab in 500 women with early-stage HER2-positive breast cancer. Patients in both arms received anti-HER2 therapy concurrently with chemotherapy during both neoadjuvant and adjuvant treatment.

The trial had a pharmacokinetic primary endpoint: noninferiority of the subcutaneous fixed-dose combination versus IV drugs for the cycle 7 trough level of pertuzumab. Secondary endpoints included cycle 7 trastuzumab trouble level, pathologic complete response (pCR), and safety.

The trial met the primary endpoint, demonstrating noninferior cycle 7 trough levels for both pertuzumab and trastuzumab. The pCR rates were virtually identical: 59.7% with Phesgo and 59.5% with the intravenous drugs. The safety profile was similar between the treatment arms with the exception of injection-site reactions, which occurred more often with Phesgo.

Adverse events (all grades) occurring in more than 30% of patients treated with Phesgo were alopecia, nausea, diarrhea, anemia, and asthenia.

The FDA granted the approval to Genentech.

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