MEDSIR has reported data from the PHERGain and PHERGain-2 trials, which focused on targeted therapies in early human epidermal growth factor receptor 2 (HER2)-positive breast cancer.
These studies aim to identify patients who may safely forgo conventional chemotherapy, reducing treatment toxicity and improving quality of life.
Results from both multi-centre, international Phase II trials were presented at the ESMO Breast 2026 scientific congress.
PHERGain enrolled 356 patients from 45 hospitals across seven European countries, including Spain, and included five-year survival data.
The study’s objective was to further validate a therapeutic de-escalation approach for patients with HER2-positive early breast cancer, utilising positron emission tomography (PET) imaging and tailored to pathological complete response (pCR), thereby enabling the omission of chemotherapy without compromising disease management or survival.
It showed that a combination of trastuzumab and pertuzumab within this adaptive model enabled approximately 30% of patients to avoid chemotherapy. Nearly 90% of participants remained recurrence-free five years after surgery.
A translational analysis of PHERGain also found that circulating tumour DNA measured by liquid biopsy offers a precise, rapid, non-invasive way to identify those likely to remain disease-free long term.
PHERGain-2 enrolled 396 patients across 47 sites in Bulgaria, Denmark, Hungary, Italy, Poland, and Spain.
It evaluated a de-escalation strategy for selected low-risk patients with tumour size between 5mm and 30mm, no nodal involvement, and high HER2 protein expression.
Focusing on chemotherapy-free, pCR-guided therapy with trastuzumab, pertuzumab, and trastuzumab emtansine (T-DM1), PHERGain-2 measured quality of life as the main safety objective.
More than half of the patients maintained a satisfactory quality of life in the first year, suggesting that avoiding chemotherapy can reduce long-term adverse effects. The observed pCR rate was 60%, though the primary efficacy endpoint remains pending.
International Breast Cancer Center Madrid and Barcelona director and the study’s principal investigator Dr Javier Cortés said: “In addition to the clinical outcomes, with nearly 90% of patients free from relapse five years after surgery, we see that the analysis of circulating tumour DNA in blood is emerging as a key tool to enable early identification of patients with a better prognosis and those who may benefit from more intensive treatment.”
