On May 7, 2026 MEDSIR, an international company and a leader in oncology research, reported the results of the PHERGain and PHERGain-2 studies at the ESMO (Free ESMO Whitepaper) Breast 2026 scientific congress. Both studies evaluate de-escalation strategies based on targeted therapies in HER2-positive early breast cancer, with the aim of identifying which patients could safely avoid standard chemotherapy without compromising therapeutic benefit. Taken together, these studies reinforce a more personalized approach focused on reducing treatment-related toxicity while better preserving patients’ quality of life.
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PHERGain is an international, multicenter, phase II clinical trial in which 356 patients were enrolled across 45 hospitals in seven European countries, including Spain. Following publication of the primary results in leading scientific journals such as The Lancet, MEDSIR has now presented the five-year survival outcomes at ESMO (Free ESMO Whitepaper) Breast 2026. The objective of the study was to further validate a therapeutic de-escalation strategy in patients with HER2-positive early breast cancer, based on PET imaging and adapted to pathological complete response (pCR), allowing chemotherapy to be omitted without compromising disease control or survival.
The study demonstrated the efficacy of the combination of trastuzumab and pertuzumab within this adaptive strategy, showing that approximately 30% of patients with localized HER2-positive early breast cancer could avoid chemotherapy. The results presented at the congress confirm the robustness of this approach, with close to 90% of patients remaining recurrence-free five years after surgery. These findings support the validity of this adaptive therapeutic strategy as a safe and durable alternative over time, prioritizing patient well-being by avoiding conventional chemotherapy and its associated toxicities.
In addition, the company presented a translational analysis of the PHERGain study showing that circulating tumor DNA detected through liquid biopsy represents a precise, rapid, and non-invasive tool with the potential to identify patients who will remain disease-free in the long term.
As highlighted during the congress by Dr. Javier Cortés, principal investigator of the study and Director of the International Breast Cancer Center in Madrid and Barcelona: "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 tumor 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."
PHERGain-2: De-escalation with a focus on quality of life
PHERGain-2, presented at ESMO (Free ESMO Whitepaper) Breast 2026 and published simultaneously in Annals of Oncology, is an international, multicenter, phase II trial that enrolled 396 patients across 47 centers in Spain, Italy, Denmark, Hungary, Poland, and Bulgaria. The study aims to demonstrate the efficacy of a de-escalation strategy in HER2-positive early breast cancer in selected low-risk patients. Specifically, it focuses on patients with tumors measuring between 5 and 30 mm, with no nodal involvement at diagnosis and high HER2 protein expression.
The trial explores a chemotherapy-free, pCR-guided strategy based on the targeted therapies trastuzumab and pertuzumab, incorporating T-DM1 within the treatment regimen. In addition, quality of life is established as the primary safety objective, placing patient-reported outcomes at the center of treatment evaluation. The results presented suggest that more than half of the patients maintain a satisfactory quality of life throughout the first year of treatment, reinforcing the notion that avoiding chemotherapy contributes to a reduction in long-term adverse effects.
With regard to efficacy, the primary endpoint is still pending. Nevertheless, the observed pCR rate of 60% is encouraging, particularly considering that treatment is initiated without chemotherapy. These findings support the clinical potential of this strategy in this patient population.
As stated by Dr. Antonio Llombart-Cussac, principal investigator of the study and Head of the Medical Oncology Department at Hospital Arnau de Vilanova in Valencia: "The results of PHERGain-2 reinforce the idea that it is possible to offer patients a therapeutic alternative that prioritizes quality of life by avoiding side effects that negatively impact physical and emotional well-being, such as fatigue, hair loss, or other health problems associated with chemotherapy."
(Press release, MedSIR, MAY 7, 2026, View Source [SID1234665357])