Should I continue Phesgo (pertuzumab and trastuzumab) as adjuvant therapy if a pathologic complete response (pCR) was not achieved?

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Last updated: June 12, 2025View editorial policy

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From the Guidelines

You should continue Phesgo (pertuzumab and trastuzumab) as adjuvant therapy even if a pathologic complete response (pCR) was not achieved after neoadjuvant therapy. The standard recommendation is to complete a total of one year (18 cycles) of HER2-directed therapy regardless of pCR status, as stated in the 2021 study 1. Phesgo is typically administered every three weeks as a subcutaneous injection.

Key Points to Consider:

  • Patients who did not achieve pCR may actually derive greater benefit from completing the full course of therapy, as residual disease indicates a higher risk of recurrence.
  • The dual HER2 blockade provided by pertuzumab and trastuzumab works through complementary mechanisms to more completely inhibit HER2 signaling pathways, potentially eliminating microscopic disease that may remain after surgery.
  • Treatment decisions should be individualized based on your specific situation, tolerance of therapy, and cardiac function monitoring, so discuss with your oncologist if you experience significant side effects or have concerns about continuing treatment. Some studies, such as the one published in 2018 1, provide additional context but do not alter the primary recommendation for completing the full course of Phesgo as adjuvant therapy.

Important Considerations:

  • The 2021 study 1 emphasizes the importance of risk-based decision-making in the treatment of HER2-positive early breast cancer, highlighting the role of pertuzumab and trastuzumab in both neoadjuvant and adjuvant settings.
  • The choice to continue Phesgo should be made in consultation with an oncologist, taking into account the patient's overall health, the presence of any residual disease, and the potential benefits and risks of continuing therapy.

From the Research

Adjuvant Therapy with Phesgo

  • Phesgo, a combination of pertuzumab and trastuzumab, is used as adjuvant therapy for HER2-positive early breast cancer 2.
  • The decision to continue Phesgo as adjuvant therapy if a pathologic complete response (pCR) was not achieved should be based on individual patient factors and overall treatment plan.

Pathologic Complete Response

  • Achieving a pCR is associated with improved outcomes in breast cancer patients 3.
  • However, the lack of pCR does not necessarily indicate a poor prognosis, and treatment decisions should be made on a case-by-case basis.
  • A study found that patients who did not achieve pCR still benefited from adjuvant therapy, including trastuzumab and pertuzumab 4.

Treatment Benefits

  • The combination of pertuzumab and trastuzumab has been shown to improve progression-free survival and overall survival in patients with HER2-positive breast cancer 4.
  • Continuing Phesgo as adjuvant therapy may still provide benefits, even if pCR was not achieved, as it can help reduce the risk of recurrence and improve overall survival.

Considerations

  • The treatment plan should be individualized, taking into account the patient's overall health, tumor characteristics, and response to treatment.
  • The decision to continue Phesgo should be made in consultation with a healthcare provider, considering the potential benefits and risks of continued treatment 2, 4.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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