PHERGain: Some HER2+ Patients Don't Need Chemotherapy

The current standard of treatment for those with HER 2 +, early stage breast cancers is dual HER2 blockade (which means the combination of the drugs trastuzamab and pertuzamab, both of which are types of HER2 targeted therapies) combined with chemotherapy.

The PHERGain phase II clinical trial tested whether or not chemotherapy is necessary for everyone with early stage, HER2+ breast cancers.

The Trial

This clinical trial randomly assigned participants with either:

Dual HER2 blockade (trastuzamab and pertuzamab) AND chemotherapy

OR

ONLY dual HER2 blockade (trastuzumab and pertuzamab)

In order to test and see if the patients who received only dual HER2 blockade were responding to their treatment, patients were administered CAT scans.

-the patients in the dual HER2 blockade only group who were responding to the drug stayed on their treatment course

-the patients in the dual HER2 blockade group who's cancer was not responding were switched over to the dual HER2 blockade + chemotherapy group.

Results

-almost 40% of the HER2-blockade only group had a complete response to the treatment; they were essentially cured, and therefore never needed chemotherapy after surgery.

-those who never received chemotherapy had less severe side effects that those who did, showcasing the benefit of forgoing chemotherapy if possible (only possible in patients who's cancer responded to the chemo-free treatment path)

-the PHERGain trial showcased the promise of a response adapted strategy (in this case, using PET scans to determine if the treatment is working, and adjusting treatment paths based on the results) in the treatment of breast cancers.

References: Breast Cancer Research Foundation. (2023). ASCO 2023: Updates from Major Breast Cancer Clinical Trials. https://www.bcrf.org/blog/bcrf-asco-2023-clinical-trials-news-updates/

The ASCO Post. (2023). PHERGain: Adapted-Response Trial Guides Treatment With Dual HER2 Blockade Alone. https://ascopost.com/issues/august-25-2023/phergain-adapted-response-trial-guides-treatment-with-dual-her2-blockade-alone/