Current therapies for HER2-positive breast cancer have limited efficacy in patients with triple-positive breast cancer (TPBC). We conduct a multi-center single-arm phase 2 trial to test the efficacy and safety of an oral neoadjuvant therapy with pyrotinib, letrozole and dalpiciclib (a CDK4/6 inhibitor) in patients with treatment-naïve, stage II–III TPBC with a Karnofsky score of ≥70 (NCT04486911). The primary endpoint is the proportion of patients with pathological complete response (pCR) in the breast and axilla. The secondary endpoints include residual cancer burden (RCB)−0 or RCB-I, objective response rate (ORR), breast pCR (bpCR), safety and changes in molecular targets (Ki67) from baseline to surgery. Following 5 cycles of 4-week treatment, the results meet the primary endpoint with a pCR rate of 30.4% (24 of 79; 95% confidence interval (CI), 21.3–41.3). RCB-0/I is 55.7% (95% CI, 44.7–66.1). ORR is 87.4%, (95% CI, 78.1–93.2) and bpCR is 35.4% (95% CI, 25.8–46.5). The mean Ki67 expression reduces from 40.4% at baseline to 17.9% (P < 0.001) at time of surgery. The most frequent grade 3 or 4 adverse events are neutropenia, leukopenia, and diarrhoea. There is no serious adverse event- or treatment-related death. This fully oral, chemotherapy-free, triplet combined therapy has the potential to be an alternative neoadjuvant regimen for patients with TPBC.

Background Mastoscopic surgery is proven to have lower incidence of postoperative complications and better postoperative recovery than traditional breast cancer surgery. This study aimed to examine the feasibility of mastoscopic modified radical mastectomy (MRM) with skin nipple-areola preservation under air cavity-free suspension hook and stage I silicone prosthesis implantation (SMALND) compared with routine MRM. Methods This was a retrospective study of patients who underwent MRM for breast cancer at the Shengjing Hospital Affiliated to China Medical University between January 1, 2019, and June 30, 2019. Surgical outcomes, complications, satisfaction, and quality of life (Functional Assessment of Cancer Therapy-Breast [FACT-B] [Chinese version]) were compared between the two groups. Results A total of 87 patients were enrolled, with 30 underwent SMALND and 57 underwent routine MRM. The intraoperative blood loss in the SMALND group was lower than in the control group (165.3±44.1 vs. 201.4±52.7 ml, P=0.001), the operation time was longer (220.5±23.9 vs. 155.6±9.2 min, P<0.001), daily axillary drainage volume was smaller (20.2±3.6 vs. 24.1±3.0 ml, P<0.001), daily subcutaneous drainage volume was smaller (15.5±2.3 vs. 19.3±3.5 ml, P<0.001), the discharge time was shorter (7.5±1.6 vs. 9.0±1.8 days, P<0.001), and FACT-B scores were higher (83.8±5.6 vs. 72.1±4.6, P<0.001). The overall satisfaction was higher in the SMALND group than in the controls (76.7% vs. 54.4%, P=0.041). Compared with the controls, the occurrence rates of nipple and flap necrosis, upper limb edema, and paraesthesia in the SMALND group were lower within 6 months (all P<0.05). Conclusions Compared with traditional MRM, SMALND had better surgical outcomes, higher satisfaction, higher quality of life, and lower complication rates.

588 Background: Despite the use of multiple lines of targeted therapy has revolutionized treatment for HER2-positive breast cancer, these methods still have limited efficacy for triple-positive breast cancer (TPBC), which calls for persistent exploration for optimized treatment strategy. This MUKDEN-01 prospective trial aimed to evaluate the efficacy of oral, chemo-sparing neoadjuvant therapy with pyrotinib, letrozole and dalpiciclib, which also meet the need for treatment convenience under COVID-19 pandemic, for patients with TPBC. Methods: The MUKDEN 01 was an investigator-initiated, multicentre, single arm, prospective phase II trial, which was performed at twelve hospitals in China(NCT04486911). Treatment-naïve patients with stage II-III tumors that according to the AJCC 8th edition criteria were eligible. Patients were treated with each cycle of 4 weeks with oral administration of pyrotinib 320 mg, and letrozole 2.5mg once daily for 4 weeks, and dalpiciclib 125 mg once daily for three weeks, followed by one week off, for five cycles. The primary endpoint was pathological complete response (pCR) in the breast and axilla (ypT0/is ypN0). Secondary endpoints included pCR in the breast (ypT0/is). residual cancer burden (RCB) score, Ki67 index change at surgery compared with baseline, and safety. Safety was analyzed in all patients, who received treatment. The study is still ongoing, and the enrollment has been completed. Results: Between June 20, 2020 and Sep. 6, 2021, 68 patients were screened for eligibility and 61 patients were recruited into this first stage of study. After surgery, 18 (29.5%, 95% CI 18.5-42.6) out of 61 patients achieving tpCR(ypT0/is ypN0), 21 (34.4%, 95% CI 22.7-47.7) patients achieved bpCR(ypT0/is). The patients with excellent pathologic response (RCB 0-1) to the combined therapy accounted for 54.1% (33/61, 95% CI 40.9-66.9). Mean Ki67 expression was reduced from 38.7% (95%CI: 31.3-46.0) at baseline to 19.3% (95% CI:13.6-25.0; p=0.0001) in the surgical samples. The most frequent grade 3 AE were neutropenia (35 [57%]), leukopenia (13 [21%]), diarrhea (9 [15%]) and oral mucositis (4 [7%]). There were five grade 4 neutropenia (8%) and one grade 4 increased AST (2%), but without other SAE and death throughout the study. Conclusions: Neoadjuvant therapy with pyrotinib, letrozole and dalpiciclib yielded a pCR rate comparable to standard chemotherapy plus dual HER2 blockade in TPBC patients. The combined therapy was also well-tolerated and provided a chemo-sparing neoadjuvant approach for TPBC patients. To our knowledge, this is the first study to evaluate the therapeutic efficacy of a chemo-free neoadjuvant treatment with HER2 TKI pyrotinib and letrozole plus CDK4/6 inhibitor dalpiciclib for TPBC patients. Further validation in a large-scale randomized controlled trial is warranted. Clinical trial information: NCT04486911.

Background. To explore the effect of age on the prognosis of patients with early stage breast cancer after breast-conserving surgery (BCS) and to provide references for young patients. Methods. All clinical data of patients with early breast cancer undergoing BCS who were treated at Shengjing Hospital of China Medical University from January 2011 to May 2016 were obtained. The primary endpoints were local recurrence (LR) and distant recurrence, and the secondary endpoint was breast cancer-specific survival (BCSS). Chi-squared tests and Fisher’s exact tests were used for statistical analysis. Disease-free survival (DFS) and BCSS were calculated by Kaplan–Meier survival analysis and compared using log-rank tests. Logistic regression was used for multivariable analysis of the effect of age in different subgroups. Propensity score matching (PSM) was used to reduce the bias confounding factors on oncological outcomes. Results. Younger patients had higher Ki-67 expression ( P = 0.048 ) and larger tumors ( P = 0.042 ) compared to older patients. No other clinical features were significantly different between age groups. There was no significant difference between the two groups in BCSS ( P = 0.186 ); however, DFS was significantly different before PSM ( P = 0.012 ). Triple-negative breast cancer and Ki-67 positivity combined with younger age at diagnosis were associated with a higher risk of recurrence ( P = 0.018 and P = 0.046 , respectively). After PSM, there were no significant differences in BCSS nor DFS between the two age groups ( P = 0.559 and P = 0.261 , respectively). Conclusion. BCS for young patients is not associated with increased DFS nor BCSS. However, young patients with triple-negative breast cancer and/or Ki-67 positivity have a poor prognosis. In sum, BCS may be appropriate for a subgroup of young patients.

e12617 Background: Both neoadjuvant chemotherapy and endocrine therapy only result in trivial pathological complete response rates and moderate objective response rate (ORR) in hormone receptor (HR)-positive, HER2-negative breast cancer, more promising alternatives are urgently needed. Tucidinostat is an oral subtype-selective histone deacetylase inhibitor that has shown efficacy and safety when used in combination with exemestane in patients with advanced HR+ breast cancer. This MUKDEN 05 study aimed to assess the efficacy and toxicity of the combination of tucidinostat and EC-T as a neoadjuvant strategy in patients with HR+/HER2-, stage II-III breast cancer. Methods: This study is a multicenter, single-arm, phase II study. Eligible patients received 20 mg tucidinostat orally twice a week (on days 1, 4, 8, and 11), 2 weeks on, 1 week off. The dose and administration schedule of EC-T were as follows: 4 cycles of epirubicin 90 mg/m2 and cyclophosphamide 600 mg/m2 every 3 weeks, followed by 4 cycles of docetaxel 100 mg/m2 every 3 weeks. The primary endpoint was the proportion of residual cancer burden (RCB) 0-I. Key secondary endpoints included pathological complete response (pCR), objective response rate (ORR), and safety. Results: Between May 2022 and August 2022, a total of 35 patients were enrolled. 27 patients were pathologically evaluable. The remaining 8 patients have completed neoadjuvant treatment and wait for operation. The ratio of RCB 0-I was 37% (95% CI, 23.2-53.7%). ORR was 86% (95% CI, 70.6-93.7%). Four (15%; 95% CI, 5.91-32.5%) patients achieved bpCR, and one (4%; 95% CI, 0.67-18.3%) patients achieved tpCR. Most adverse events (AEs) were grade 1 or 2. Grade 3/4 AEs included neutropenia (21.1%), and thrombocytopenia (15.8%). Conclusions: The combination of Tucidinostat and EC-T had an acceptable safety profile and encouraging clinical responses, offering a neoadjuvant treatment option for patients with early HR+/HER2- breast cancer. Further research is required to validate these findings. Clinical trial information: NCT05400993 .