The dynamics of adjuvant therapy selection for HER2-positive breast cancer in real clinical practice: the third consecutive analysis of physicians’ preferences in the Russian Federation

Neoadjuvant chemotargeted therapy for HER2 positive breast cancer, incorporating two monoclonal antibodies (trastuzumab and pertuzumab), enables achieving the maximum rate of pathologic complete responses (pCR), which significantly improves the prognosis and long term treatment outcomes. According to our data, even in a patient population “enriched” with locally advanced inoperable tumours (T4 or N 2–3), the use of the TCHP regimen ensures a pCR rate exceeding 60 %. Based on the findings of the phase 3 randomized clinical trial KATHERINE, in cases where residual tumour of any size is detected (RCB I, II, and III), administration of post neoadjuvant therapy with trastuzumab emtansine (T-DM1) significantly improves survival. However, in the Russian Federation, the indication for adjuvant therapy with T-DM1 is limited to RCB II and III only. In contrast, for RCB I (minimal residual tumour), adjuvant therapy with trastuzumab – which is part of the NACHTT regimen – is recommended. To assess real-world clinical practice in the Russian Federation and identify trends in physicians’ preferences for adjuvant targeted therapy, the third consecutive survey study “Therapy for HER2-Positive Breast Cancer” (conducted in 2021, 2023, and 2025) was carried out. The survey included questions addressing the post-neoadjuvant phase. Fifty oncology specialists from six regions of the country (Central, Northwestern, Siberia/Far East, Southern, Ural, and Volga regions) participated in the survey. These specialists either independently or as part of a tumor board prescribe treatment for patients diagnosed with HER2-positive breast cancer. This publication presents the results of assessing specialists’ preferences in prescribing adjuvant and post-neoadjuvant therapy. In 2025, neoadjuvant chemotargeted therapy (NACTT) was prescribed/planned for only 75 % of patients with early-stage (M0) HER2+ BC, which is slightly lower compared to previous surveys. According to the respondents, the pCR rate after NACHTT was 49 %; RCB I was reported in another 23 % of cases, while pathological response assessment was not performed in 2 % of cases. Thus, the proportion of patients with moderate to severe residual tumour (RCB II–III) after NACHTT significantly decreased in 2025, reaching only 26 %, compared to 35 % in 2023. The vast majority of patients with RCB II–III (88 %) received post-neoadjuvant T-DM1 adjuvant therapy in 2025, compared to 68 % in 2023 and 24 % in 2021. Additionally, T-DM1 was occasionally prescribed in the Russian clinical practice for RCB I cases as well. Analyzing adherence to the post-neoadjuvant T-DM1 therapy plan, high patient compliance and good drug tolerability were noted: 82.2 % completed the full course of 14 cycles, while another 17.4 % received 7 to 13 cycles. Overall, when selecting a drug treatment regimen for early operable and locally advanced inoperable HER2-positive BC in the Russian Federation, the priority is given to therapy efficacy and safety. The significance of the issue of drug availability is steadily decreasing.

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