Chicago, Jun 3 (EFE).- Adapting breast cancer therapy based on patient response can eliminate the need for chemotherapy in a significant number of treatments that currently default to it, according to a study suggesting that a third of patients can successfully avoid this technique.
The phase II PHERGain clinical trial, spearheaded by Spanish-American oncology research company MEDSIR, shared its findings in Chicago on Friday, the first day of the annual meeting of the American Society of Clinical Oncology (ASCO). The event, which is the sector’s leading gathering, convening around 40,000 professionals, runs until Tuesday.
Between June 2017 and April 2019, the study involved 356 patients over 18 with operable HER2+ breast cancer in its initial stage, from I to III. This aggressive subtype traditionally opts for chemotherapy as the standard treatment.
Group A patients received a combination of chemotherapy and the drugs trastuzumab and pertuzumab, while Group B’s treatment was adaptive, designed to bypass chemotherapy based on individual progress.
The latter group began with two cycles of pertuzumab, trastuzumab, and endocrine therapy. If the Positron Emission Tomography (PET) scan showed a response, they underwent another six cycles without chemotherapy.
After six treatment cycles, Group A patients underwent surgery, while Group B patients did so after eight cycles. Post-surgery, those who showed no signs of cancer (known as complete pathological response or pCR) continued treatment without chemotherapy. The rest had it added.
Led by Drs. Javier Cortés, Antonio Llombart-Cussac, and José Pérez, the study aimed to assess both the percentage of pCR in the breast and axilla at the time of surgery in those responding well to the PET scan, as well as disease-free survival after three years.
In 2021, The Lancet reported that 37.9% of Group B patients who responded to treatment achieved a complete pathological response. On Friday, at the Chicago conference, the second criterion, survival rates, were unveiled.
In Group B, as Cortés emphasized during the presentation, both patients who eventually received chemotherapy and those who managed to continue without it were included. 95.4% of patients (255) in this group had no relapse three years later, and among those who managed to avoid chemotherapy throughout the trial, nearly 30%, that percentage rose to almost 99%.
Researchers from 45 centers across seven European countries – Spain, France, Belgium, Germany, Italy, Portugal, and the UK – participated in the study. The team stresses that it is the first to gradually adjust treatment based on response, deviating from the standard chemotherapy option.
MEDSIR, co-founded in 2012 by Cortés and Llombart-Cussac among others, notes that about one in five breast cancers have cancer cells with additional copies of the gene producing the HER2 protein. This type of cancer tends to be more aggressive than others.
The typical treatment combines chemotherapy, trastuzumab, and pertuzumab. But the promising results obtained with the latter two drugs alone now question the mandatory recourse to chemotherapy, a more toxic technique with greater side effects.
The findings are therefore encouraging, demonstrating that in certain patients with early-stage or less advanced tumors, it’s possible and safe to avoid chemotherapy without jeopardizing the final outcome.
“I would like to thank the patients and their families, the researchers, and the entire team for trusting us and allowing us to carry out this independent research,” concluded Cortés, a professor at the Universidad Europea de Madrid and director of the International Breast Cancer Center in Barcelona and Madrid. EFE