Investigating the Correlation Between Long-Term Response in Patients with Metastatic HER2+ Breast Cancer and the Activity of Regulatory T Cells: A Retrospective Study

Mustafa Degirmenci,1 Gulden Diniz,2 Dudu Solakoglu Kahraman,3 Mustafa Sahbazlar,4 Lokman Koral,5 Umut Varol,6 Ruchan Uslu7 1Department of Medical Oncology, Health Sciences University, Izmir, Turkey; 2Department of Pathology, Izmir Democracy University, Izmir, Turkey; 3Department of Pathology, University of Health Sciences, Izmir, Turkey; 4Department of Medical Oncology, Celal Bayar University, Manisa, Turkey; 5Department of Medical Oncology, Canakkale Onsekiz Mart University, Canakkale, Turkey; 6Department of Medical Oncology, Izmir Democracy university, Izmir, Turkey; 7Department of Medical Oncology, izmir Medicana Hospital, Izmir, TurkeyCorrespondence: Mustafa Degirmenci, Medical Oncology Department of Health Sciences University, Kazım Dirik Mah. Fatih Sultan Mehmet Cad. No: 29/1 Seyhan Sitesi C blok D:10 35040, Bornova, Izmir, Turkey, Email [email protected]: Trastuzumab is commonly utilized in the management of metastatic HER2-positive breast cancer. Our main goal was to examine the clinical outcomes and immune markers of patients who received trastuzumab and chemotherapy treatment.Methods: Between 1995 and 2012, a total of 98 patients diagnosed with metastatic HER2-positive breast cancer were retrospectively analyzed at Ege University Hospital and Tepecik Training and Research Hospital. The clinicopathological characteristics and clinical outcomes of the patients were assessed, and the associations between response rates, survival and the immune profiles of tumor infiltrating lymphocytes were statistically evaluated.Results: The average age of patients at the time of diagnosis was 50.1± 10.3 (ranging from 30 to 79) years. The mean follow-up period for all patients was 97.9± 53.8 months. Among the patients, complete response was observed in 24.5%, partial response in 61.2%, and stable disease in 8.2% of cases. The average progression-free survival was 50.3± 26.9 months (ranging from 1 to 163 months), and the average overall survival was 88.8± 59.4 months (ranging from 12 to 272 months). After analyzing all cases, it was found that patients who were younger (p=0.006), exhibited higher CD3-positivity (p=0.041), presented with higher FOXP3-positivity (p=0.025), showed complete or at least partial response to treatment (p=0.008), and experienced a long-term response to trastuzumab (and chemotherapy) treatment had longer survival (p=0.001).Conclusion: Patients with HER2-positive breast cancer, who initially respond positively to palliative trastuzumab and chemotherapy treatment, can achieve long-term tumor remission lasting for several years.Keywords: metastatic breast cancer, trastuzumab, forkhead box p3, long-term response