The combination of hormone therapy, trastuzumab and palbociclib reduces the risk of breast cancer progression by 48%

SOLTI, a reference group for clinical cancer research in Spain, presented the results of its PATRICIA-Cohort C study during the American Society of Clinical Oncology (ASCO) 2024 Congress, which took place from May 31 to June 4 in Chicago, USA. The data presented demonstrate that the combination of hormonal therapy, trastuzumab and palbociclib is a more effective and better tolerated option than conventional treatment consisting of chemotherapy and trastuzumab in patients with advanced ER+/HER2+ breast cancer. In this group of patients with advanced breast cancer, molecularly selected as Luminal A and B, a new combination reduces the risk of disease progression by 48 percent.

Of the group of patients with HER2+ breast cancer, approximately 50 percent also exhibit estrogen receptor positivity (ER+). However, this group exhibits molecular heterogeneity that may explain differences in patient prognosis and development. Therefore, it is important to improve the molecular characterization of these tumors (ER+/HER2+) through specific expression analysis of certain genes. Thus, patients whose tumors express estrogen receptor-related genes (Intrinsic subtype Luminal A or B) are those that benefit significantly from the combination of hormone therapy, trastuzumab, and palbociclib, reducing the risk of progression by nearly half compared with traditional treatment with chemotherapy and/or anti-HER2 drugs.

“This is the first study to demonstrate that molecular selection of patients with HER2+/ER+ advanced breast cancer has prognostic value and allows for novel chemotherapy-free treatment combinations,” he explained. Eva Ciruelos, Vice President of SOLTI and Coordinator of the Breast Cancer Unit of the 12 October Hospital in Madrid and HM Hospitales, and Principal Investigator of the PATRICIA Study. “These combinations not only demonstrate greater efficacy than traditional treatments, but also offer the opportunity to improve patient tolerability and quality of life. With this therapeutic alternative, the average time to progression for patients with experimental treatment is 9.1 months, compared to 7.5 months with conventional treatment,” he added.

PATRICIA Studio

The PATRICIA study is a phase II clinical trial. In the first phase, the efficacy and safety of the combination of palbociclib and trastuzumab with or without hormonal therapy was assessed in previously treated postmenopausal patients with HER2+ metastatic breast cancer. Results from cohorts A and B in ER+/HER2+ advanced breast cancer showed that the combination of hormonal therapy, trastuzumab and palbociclib was safe and showed promising results in terms of survival. for tumors molecularly classified as Luminal A or B subtypes. Based on these results, the study was expanded to Cohort C, prospectively recruiting triple-positive patients with Luminal A or B molecular subtype. A total of 73 patients were enrolled in the PATRICIA II trial. . This study, promoted by the academic research group SOLTI, was supported by Pfizer, PAS to PAS and grants from the Spanish Society of Medical Oncology (SEOM).

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