Total Pathologic Complete Response Research Articles

Abstract PO1-03-11: Camrelizumab in Combination with Nab-Paclitaxel and Carboplatin versus Nab-Paclitaxel and Carboplatin as Neoadjuvant Therapy for Triple Negative Breast Cancer: A Multicenter, Open-Label, Randomized Controlled Study

Abstract Background: Triple-negative breast cancer (TNBC) is recognized for its aggressive nature and unfavorable prognosis. Immune checkpoint inhibitors have demonstrated promising antitumor activity in both neoadjuvant and metastatic settings. This study aimed to assess the efficacy and safety of camrelizumab, an anti-PD-1 antibody, in conjunction with chemotherapy as a neoadjuvant treatment for early-stage TNBC. Methods: This two-phase prospective, multicenter, randomized controlled study was initiated with the enrollment of previously untreated stage II-III TNBC patients in the first phase. They received neoadjuvant therapy comprising six 3-week cycles of camrelizumab (200 mg, q3w), along with nab-paclitaxel (220 mg/m2, q3w) and carboplatin (AUC 5, q3w). In the second phase, patients were enrolled and randomized 1:1 to either the camrelizumab plus nab-paclitaxel and carboplatin group or the nab-paclitaxel plus carboplatin group. The present report covers the data from the first phase of the study. The primary endpoint was the total pathological complete response (tpCR, ypT0/is ypN0) rate. Secondary endpoints included breast pathological complete response (bpCR, ypT0/is) rate, objective response rate (ORR), event-free survival (EFS), residual cancer burden (RCB), and safety. This study is registered with ClinicalTrials.gov, under the identifier NCT04907344. Results: Between September 2021 and March 2023, 39 patients were enrolled in the first phase. A total of 35 (89.7%) were node-positive. Among the 32 patients with evaluable efficacy, the tpCR rate was 59.4% (19/32), and the bpCR rate was 68.8% (22/32). The ORR at the end of neoadjuvant treatment stood at 87.2% (34/39). Among the 39 patients, 11 (28.2%) experienced grade 3 or higher treatment-related adverse events, the most common of which were thrombocytopenia (6 [15.4%]), leucopenia (5 [12.8%]), neutropenia (5 [12.8%]), alanine aminotransferase increased (2 [5.1%]), aspartate aminotransferase increased (1 [2.6%]), and hypothyroidism (1 [2.6%]). Adverse events leading to discontinuation of any agent occurred in 5 (12.8%) patients, while adverse events leading to delay in treatment occurred in 7 (17.9%) patients. Serious treatment-related adverse events were reported by 4 (10.4%) patients. Conclusions: In patients with early TNBC, the neoadjuvant treatment of camrelizumab in combination with nab-paclitaxel and carboplatin demonstrated a high pCR rate with an acceptable safety profile. The second phase of the study is currently in progress to validate these findings. Citation Format: Weipeng Zhao, Xin Wang, Bin Zhang, Yehui Shi, Chen Wang, Xu Wang, Shufen Li, Chunfang Hao, Ning Lu, Yongsheng Jia, Li Zhang, Lan Zhang, Weixin Sun, Xuchen Cao, Zhongsheng Tong. Camrelizumab in Combination with Nab-Paclitaxel and Carboplatin versus Nab-Paclitaxel and Carboplatin as Neoadjuvant Therapy for Triple Negative Breast Cancer: A Multicenter, Open-Label, Randomized Controlled Study [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-03-11.

Abstract PO2-02-05: CDK4/6 inhibitor dalpiciclib combined with letrozole as neoadjuvant therapy in postmenopausal patients with hormone receptor-positive, HER2-negative stage II-III breast cancer: a single-arm exploratory trial

Abstract Background: Patients with HR-positive, HER2-negative breast cancer respond poorly to neoadjuvant chemotherapy. The phase 3 DAWNA-1 and DAWNA-2 studies have proved that adding dalpiciclib (a CDK4/6 inhibitor) to endocrine therapy can significantly improve progression-free survival in patients with hormone receptor (HR)-positive, HER2-negative advanced breast cancer. However, the evidence of dalpiciclib in the neoadjuvant setting is limited. This study aimed to explore the efficacy and safety of dalpiciclib plus letrozole as neoadjuvant therapy in in patients with HR-positive, HER2-negative stage II-III breast cancer. Methods: In this multicenter, single-arm exploratory trial (NCT05512780), adult postmenopausal women with HR-positive (estrogen receptor >10%), HER2-negative stage II-III invasive breast cancer were enrolled. Patients received oral dalpiciclib (150 mg on days 1-21 of each 28-day cycle) and oral letrozole (2.5 mg once daily) for 4 cycles, followed by surgery. The primary endpoint was objective response rate (ORR), assessed by investigator according to the Response Evaluation Criteria In Solid Tumors version 1.1. Secondary endpoints included complete cell cycle arrest (CCCA, defined as Ki-67 < 2.7% on day 15 of the first cycle) rate, total pathological complete response (tpCR; ypT0/is ypN0) rate, residual cancer burden (RCB) 0-I rate, and safety. Results: Between June 2022 and January 2023, 41 patients were screened at 9 sites, and 35 patients were enrolled and received at least one dose of study drug. The median age was 66 years (range, 52-83), and the median baseline Ki-67 level was 20% (range, 4%-40%). The majority of patients had T2 disease (65.7%), lymph node-positive disease (88.6%), and stage II disease (IIA: 45.7%; IIB: 40.0%). The ORR was 35.5% (11/31) at 8 weeks and 51.7% (15/29) at 16 weeks in patients with evaluable response. The CCCA rate was 70.0% (21/30) in patients with available data. Four patients refused surgery and chose to continue the drug therapy. Of 27 patients who had undergone surgery, one (3.7%) patient had tpCR and RCB 0. Of 35 patients, the most common adverse events were neutrophil count decreased (74.3%), white blood cell decreased (68.6%), anemia (34.3%), and fatigue (31.4%). The most common grade 3 or higher adverse event was neutrophil count decreased (45.7%). No febrile neutropenia or treatment-related deaths occurred. Conclusions: This is the first prospective study of neoadjuvant dalpiciclib in patients with HR-positive, HER2-negative breast cancer. The findings suggest the promising tumor response to neoadjuvant dalpiciclib plus letrozole in postmenopausal patients with HR-positive, HER2-negative breast cancer, with a manageable safety profile. This combination can effectively suppress the tumor cell proliferation, as reflected by change in Ki-67 level. Citation Format: Lina Zhang, Chao Yang, Jie Ma, Yuntao Li, Ruizhen Luo, Jianjun Han, Xiaochun Wang, Zhisheng Zhang, Li Ma, Haifeng Cai, Xiangshun Kong, Zunyi Wang, Xinping Zhou, Yueping Liu, JiaJie Shi, Yanshou Zhang, Meiqi Wang, Jiaxing Wang, Cuizhi Geng. CDK4/6 inhibitor dalpiciclib combined with letrozole as neoadjuvant therapy in postmenopausal patients with hormone receptor-positive, HER2-negative stage II-III breast cancer: a single-arm exploratory trial [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-02-05.

Abstract PO1-27-01: Comparing the Efficacy and Safety of TQB2440 versus the Reference Pertuzumab for the Treatment of HER2-Positive Early or Locally Advanced Breast Cancer: A Multicenter, Randomized, Double-Blind, Parallel-Controlled Phase 3 Trial

Abstract Background: Pertuzumab is a recombinant humanized monoclonal antibody targeting the extracellular dimerization domain II of HER2. On September 30, 2013, the FDA have granted accelerated approval of a pertuzumab regimen for neoadjuvant treatment of patients (pts) with high-risk, HER2-positive early stage breast cancer. TQB2440 is a pertuzumab (Perjeta®, Roche) biosimilar. This study aimed to compare the efficacy and safety of TQB2440 and the reference pertuzumab combined with trastuzumab and docetaxel in pts with HER2-positive early or locally advanced breast cancer. Methods: In this multicenter, randomized, double-blind phase 3 study, eligible pts were aged 18-75 with operable HER2-positive (IHC 3+ or ISH+) clinical stage II-IIIC breast cancer negative for ER/PR and had an ECOG PS of 0-1. The pts were randomly assigned to receive either TQB2440 or the reference pertuzumab (Perjeta®) (840 mg on day 1, cycle 1, followed by 420 mg on cycle 2-4, q3w) added to trastuzumab (8 mg/kg on day 1, cycle 1, followed by 6 mg/kg for cycles 2-4, q3w) + docetaxel (75 mg/m2, cycle 1-4, q3w). The pts then underwent surgery followed by adjuvant treatment with FEC regimens (fluorouracil 600 mg/m², epirubicin 90 mg/m², cyclophosphamide 600 mg/m², cycle 5-7, q3w), then TQB2440 (840 mg on day 1, cycle 8, followed by 420 mg on cycle 9-20, q3w) + trastuzumab (8 mg/kg on day 1, cycle 8, followed by 6 mg/kg for cycles 9-20, q3w) or until disease progression or intolerable toxicity. The primary endpoint was total pathologic complete response (tpCR) by independent review committee (IRC). Equivalence was established if the 90% confdence intervals (CIs) of the relative ratio [RR] within the interval of 0.76 to 1.32. Secondary endpoints included breast pathologic complete response (bpCR) by IRC, tpCR & bpCR by investigator, breast conserving surgery (BCS) rates, objective response rate (ORR), event-free survival (EFS), disease-free survival (DFS), OS and safety. Results: Between October 21, 2020, and November 21, 2022, 412 pts were enrolled (TQB2440 group, n=207; the reference pertuzumab group, n=205). Data cutoff was November 30, 2022. In the intention-to-treat (ITT) population, the tpCR by IRC of the TQB2440 group and the reference drug group were 58.94% and 58.05%, respectively. The RR was 1.02 (90% CI, 0.89, 1.16), which was within the predefined equivalence interval of 0.76 to 1.32. There was no statistically significant difference in the bpCR by IRC between the TQB2440 group and the reference pertuzumab group (67.63% [95% CI, 60.80%, 73.95%] vs. 63.90% [95% CI, 56.92%, 70.48%], P=0.4249). The BCS rate also comparable between the two groups with 13.04% (95% CI, 8.77%, 18.41%) vs. 13.17% (95% CI, 8.86%, 18.58%) (P=0.9695). Additionally, the results of the PP (per-protocol) population were similar to those of the ITT population. The incidence of treatment-related adverse events (TRAEs) and grade ≥3 TRAEs were similar between the TQB2440 group and the reference pertuzumab group with 79.71% vs. 75.98% and 49.28% vs. 41.67%, respectively. Conclusion: In patients with HER2-positive early or locally advanced breast cancer, TQB2440 demonstrated equivalent efficacy and similar safety to the reference pertuzumab. Clinical trial information: NCT05985187. Research Sponsor: Chia Tai Tianqing Pharmaceutical Group Co., Ltd Citation Format: Qingyuan Zhang, Shusen Wang, Nanlin Li, Qiao Cheng, Yu ren, Xuchen Cao, Jianjun Huang, Caigang Liu, Hongwei Yang, Limin Wei, Zhangjun Song, Huadong Zhao, Fangling Ning, Xiaojia Wang, Dehong Zou, Xiaohua Zeng, Jie Hao, Yunjiang Liu, Huijuan Wang, Nie Jianyun, Liang Li, Lina Liu, Tao Sun, Xiaobo Hu, Zhenhua Zhai, Huihua Xiong, Yuanqi Zhang, Enxiang Zhou, Jing Sun, Zhenhai Cai, Antai Zhang, Shui Wang, Junyang Mo, Qun Su, Xiuheng Qi, Guoren Zhou, Shuqun Zhang, Guozhong Cui, Wei Wang, Mingjiang Fan, Xinyu Qian, Xinhong Wu, Zhihong Wang, Jiuda Zhao, Yonghui Luo, Yanming Zhang, Fuguo Tian, Jiye Zhang, Dongning Chai, Qingshan Li. Comparing the Efficacy and Safety of TQB2440 versus the Reference Pertuzumab for the Treatment of HER2-Positive Early or Locally Advanced Breast Cancer: A Multicenter, Randomized, Double-Blind, Parallel-Controlled Phase 3 Trial [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-27-01.

Abstract PO1-01-02: Final analysis of neoadjuvant chemotherapy with pegylated liposomal doxorubicin/cyclophosphamide followed by taxanes with full-course trastuzumab/pertuzumab for HER2-positive breast cancer: a single-arm, phase II study

Abstract Background: The optimal neoadjuvant treatment regimen for HER2-positive breast cancer remains unclear, especially regarding the use of anthracycline. We conducted a prospective phase II study to evaluate sequential neoadjuvant chemotherapy with pegylated liposomal doxorubicin (PLD)/cyclophosphamide followed by taxanes in the presence of full-course trastuzumab/pertuzumab in HER2-positive early breast cancer patients. Methods: In this single-arm, open-label, multicenter, phase II study, eligible patients with confirmed HER2-positive early breast cancer were recruited from four independent hospitals. Patients received four cycles of PLD (35 mg/m2) and cyclophosphamide (600 mg/m2), followed by four cycles of taxanes (docetaxel, 100 mg/m2 or nab-paclitaxel, 260 mg/m2), concomitant with eight cycles of trastuzumab (8 mg/kg loading dose, then 6 mg/kg) and pertuzumab (840 mg loading dose, then 420 mg) every 3 weeks. The primary endpoint was total pathological complete response (ypT0/is ypN0, tpCR). Secondary endpoints included breast pCR (bpCR), objective response rate (ORR), disease control rate, the proportion of patients requiring breast-conserving surgery, and safety. For biomarkers analysis, tumor tissues were collected at baseline and evaluated for Topoisomerase 2 Alpha (TOP2A) expression assessed prospectively with immunohistochemistry (IHC) assay by independent pathologists. Results: Between May 27, 2020 and May 11, 2022, 78 eligible patients were treated and underwent surgery, of whom 42 (53.8%) patients underwent breast-conserving surgery. After neoadjuvant therapy, 47 (60.3%, 95% CI, 48.5%-71.2%) patients achieved a tpCR in the breast and axilla. The bpCR was observed in 49 (62.8%) patients. ORRs were 76.9% (95% CI, 66.0%-85.7%) and 93.6% (95% CI, 85.7%-97.9%) after 4-cycle and 8-cycle neoadjuvant therapy, respectively. All (100%) patients achieved disease control since the end of the first cycle. No correlations between clinicopathological variables and pathological response were observed. Grade 3 or worse AEs occurred in 35 (44.9%) patients. Nine (11.5%) patients experienced asymptomatic LVEF reduction (≥10% from baseline), but all with a minimum value of >55%. No treatment-related surgical delay or death occurred. For biomarkers analysis, the status of TOP2A was not found to be associated with pCR or 4th-cycle ORR. Conclusions: This dual HER2-blockade plus polychemotherapy as sequential neoadjuvant regimen demonstrates promising anti-tumor activity and acceptable tolerability for patients with HER2-positive breast cancer. Citation Format: Yaping Yang, Liang Jin, Yudong li, Fengxia Gan, Nanyan Rao, Jun Zhang, Ruifa Feng, Zhenzhen Liu, Qiang Liu. Final analysis of neoadjuvant chemotherapy with pegylated liposomal doxorubicin/cyclophosphamide followed by taxanes with full-course trastuzumab/pertuzumab for HER2-positive breast cancer: a single-arm, phase II study [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-01-02.

Neoadjuvant–adjuvant pertuzumab in HER2-positive early breast cancer: final analysis of the randomized phase III PEONY trial

The randomized, multicenter, double-blind, placebo-controlled, phase III PEONY trial (NCT02586025) demonstrated significantly improved total pathologic complete response (primary endpoint) with dual HER2 blockade in HER2-positive early/locally advanced breast cancer, as previously reported. Here, we present the final, long-term efficacy (secondary endpoints: event-free survival, disease-free survival, overall survival) and safety analysis (62.9 months’ median follow-up). Patients (female; n = 329; randomized 2:1) received neoadjuvant pertuzumab/placebo with trastuzumab and docetaxel, followed by adjuvant 5-fluorouracil, epirubicin, and cyclophosphamide, then pertuzumab/placebo with trastuzumab until disease recurrence or unacceptable toxicity, for up to 1 year. Five-year event-free survival estimates are 84.8% with pertuzumab and 73.7% with placebo (hazard ratio 0.53; 95% confidence interval 0.32–0.89); 5-year disease-free survival rates are 86.0% and 75.0%, respectively (hazard ratio 0.52; 95% confidence interval 0.30–0.88). Safety data are consistent with the known pertuzumab safety profile and generally comparable between arms, except for diarrhea. Limitations include the lack of ado-trastuzumab emtansine as an option for patients with residual disease and the descriptive nature of the secondary, long-term efficacy endpoints. PEONY confirms the positive benefit:risk ratio of neoadjuvant/adjuvant pertuzumab, trastuzumab, and docetaxel treatment in this patient population.

Two Hematological Markers Predicting the Efficacy and Prognosis of Neoadjuvant Chemotherapy Using Lobaplatin Against Triple-Negative Breast Cancer.

Our previous work indicated that the addition of lobaplatin to combined therapy with taxane and anthracycline can improve the pathological complete response rate of neoadjuvant therapy for triple-negative breast cancer (TNBC) and lengthen long-term survival significantly, but the therapeutic markers of this regimen are unclear. Eighty-three patients who met the inclusion criteria were included in this post hoc analysis. We analyzed the association between platelet-to-lymphocyte ratio (PLR) and neutrophil-to-lymphocyte ratio (NLR) before neoadjuvant chemotherapy with the efficacy and prognosis after treatment with docetaxel, epirubicin, and lobaplatin neoadjuvant chemotherapy regimen. χ2 test and Cox regression were used to analyze the association between PLR and NLR with total pathologic complete response (tpCR), as well as the association between PLR and NLR with event-free survival (EFS) and overall survival (OS), respectively. The tpCR rate in the PLR- group was 49.0% (25/51), which was significantly higher than that in the PLR+ group (25.0% [8/32], P = .032). The tpCR rate in the NLR- group was 49.1% (26/53), which was significantly higher than that in the NLR+ group (23.3% [7/30], P = .024). The tpCR rate of the PLR-NLR- (PLR- and NLR-) group was 53.7% (22/41), which was significantly higher than that of the PLR+/NLR+ (PLR+ or/and NLR+) group (26.1% [11/42]; P = .012). EFS and OS in the NLR+ group were significantly shorter than those in the NLR- group (P = .028 for EFS; P = .047 for OS). Patients in the PLR-NLR- group had a longer EFS than those in the PLR+/NLR+ group (P = .002). PLR and NLR could be used to predict the efficacy of neoadjuvant therapy with the taxane, anthracycline, and lobaplatin regimen for patients with TNBC, as patients who had lower PLR and NLR values had a higher tpCR rate and a better long-term prognosis.

Short-term efficacy and safety of neoadjuvant pyrotinib plus taxanes for early HER2-positive breast cancer: a single-arm exploratory phase II trial.

The effectiveness and safety of pyrotinib have been substantiated in human epidermal growth factor receptor 2 (HER2)-positive advanced breast cancer (BC). However, the role of pyrotinib as a single HER2 blockade in neoadjuvant setting among BC patients has not been studied. The objective of this study was to evaluate the efficacy and tolerability of pyrotinib plus taxanes as a novel neoadjuvant regimen in patients with HER2-positive early or locally advanced BC. In this single-arm exploratory phase II trial, patients with treatment-naïve HER2-positive BC (stage IIA-IIIC) received pyrotinib 400 mg once daily and taxanes [docetaxel 75 mg/m2 or nanoparticle albumin-bound (nab)-paclitaxel 260 mg/m2 every 3 weeks, or paclitaxel 80 mg/m2 weekly] for a total of four 21-day cycles before surgery. Efficacy assessment was based on pathological and clinical measurements. The primary endpoint of this study was the total pathological complete response (tpCR) rate. The secondary endpoints included breast pCR (bpCR) rate, investigator-assessed objective response rate (ORR) and adverse events (AEs) profiles. From 1 September 2021 to 30 December 2022, a total of 31 patients were enrolled. One patient was withdrawn due to unbearable skin rash after the second cycle of neoadjuvant therapy. The majority of the intention-to-treat (ITT) population was premenopausal (54.8%), had large tumors (90.3%) and metastatic nodes (58.1%) at diagnosis and hormone-receptor positive tumors (64.5%). Most participants used nab-paclitaxel (74.2%) and received mastectomy (67.7%) after neoadjuvant treatment. The tpCR and bpCR rates were 48.4% [95% confidence interval (CI): 30.8-66%] and 51.6% (95% CI: 34-69.2%), respectively. Grade ≥3 treatment-related AEs were observed in 16.1% (5/31) of the ITT population, including diarrhea (n=2, 6.5%), hand and foot numbness (n=1, 3.2%), loss of appetite (n=1, 3.2%), and skin rash (n=1, 3.2%). AE related dose reduction or pyrotinib interruption was not required. In female patients with HER2-positive non-metastatic BC, neoadjuvant pyrotinib monotherapy plus taxanes appears to show promising clinical benefit and controllable AEs [Chinese Clinical Trial Registry (ChiCTR2100050870)]. The long-term efficacy and safety of this regime warrant further verification.

A pilot trial of neoadjuvant pyrotinib plus trastuzumab, dalpiciclib, and letrozole for triple-positive breast cancer.

Triple-positive breast cancer (TPBC) poorly responds to current standard neoadjuvant therapy (trastuzumab plus pertuzumab and chemotherapy). Our previous MUKDEN 01 study showed a promising total pathological complete response (tpCR) rate of 30.4% with neoadjuvant pyrotinib (pan-human epidermal growth factor receptor tyrosine kinase inhibitor) plus dalpiciclib (cyclin-dependent kinase 4/6 inhibitor) and letrozole, but the efficacy remains suboptimal. This pilot study (NCT05228951) explored adding trastuzumab to this triplet neoadjuvant regimen in patients with stage II-III TPBC. The primary endpoint was tpCR (ypT0/is, ypN0) rate. Between February 2022 and June 2022, 12 patients were enrolled, and seven (58%; 95% confidence interval [CI], 27.7%-84.8%) patients achieved tpCR. The rate of residual cancer burden (RCB) 0-I was 75% (95% CI, 46.8%-91.1%). The objective response rate (ORR) was 92% (95% CI, 64.6%-98.5%). Mean Ki-67 level was significantly reduced from 45.0% (95% CI, 19.5%-70.5%) at baseline to 17.2% (95% CI, 0.7%-33.7%) after neoadjuvant therapy (p=0.03). The most common grade 3 adverse events were diarrhea (four [33%]) and decreased neutrophil count (three [25%]). No grade 4 adverse events or treatment-related deaths occurred. This four-drug neoadjuvant regimen shows promising pathological response with an acceptable safety profile in patients with TPBC. A randomized controlled trial (NCT05638594) of this regimen is being conducted.

Sequential neoadjuvant chemotherapy using pegylated liposomal doxorubicin and cyclophosphamide followed by taxanes with complete trastuzumab and pertuzumab treatment for HER2-positive breast cancer: A phase II single-arm study.

Despite cardiotoxicity overlap, the trastuzumab/pertuzumab and anthracycline combination remains crucial due to significant benefits. Pegylated liposomal doxorubicin (PLD), a less cardiotoxic anthracycline, was evaluated for efficacy and cardiac safety when combined with cyclophosphamide and followed by taxanes with trastuzumab/pertuzumab in human epidermal growth factor receptor-2 (HER2)-positive early breast cancer (BC). In this multicenter, phase II study, patients with confirmed HER2-positive early BC received four cycles of PLD (30-35 mg/m2) and cyclophosphamide (600 mg/m2), followed by four cycles of taxanes (docetaxel, 90-100 mg/m2 or nab-paclitaxel, 260 mg/m2), concomitant with eight cycles of trastuzumab (8 mg/kg loading dose, then 6 mg/kg) and pertuzumab (840 mg loading dose, then 420 mg) every 3 weeks. The primary endpoint was total pathological complete response (tpCR, ypT0/is ypN0). Secondary endpoints included breast pCR (bpCR), objective response rate (ORR), disease control rate, rate of breast-conserving surgery (BCS), and safety (with a focus on cardiotoxicity). Between May 27, 2020 and May 11, 2022, 78 patients were treated with surgery, 42 (53.8%) of whom had BCS. After neoadjuvant therapy, 47 [60.3%, 95% confidence interval (95% CI), 48.5%-71.2%] patients achieved tpCR, and 49 (62.8%) achieved bpCR. ORRs were 76.9% (95% CI, 66.0%-85.7%) and 93.6% (95% CI, 85.7%-97.9%) after 4-cycle and 8-cycle neoadjuvant therapy, respectively. Nine (11.5%) patients experienced asymptomatic left ventricular ejection fraction (LVEF) reductions of ≥10% from baseline, all with a minimum value of >55%. No treatment-related abnormal cardiac function changes were observed in mean N-terminal pro-BNP (NT-proBNP), troponin I, or high-sensitivity troponin. This dual HER2-blockade with sequential polychemotherapy showed promising activity with rapid tumor regression in HER2-positive BC. Importantly, this regimen showed an acceptable safety profile, especially a low risk of cardiac events, suggesting it as an attractive treatment approach with a favorable risk-benefit balance.

Neoadjuvant pyrotinib plus trastuzumab and chemotherapy for HER2-positive breast cancer: a prospective cohort study

BackgroundThis prospective study aims to investigate the efficacy and safety of pyrotinib (P) combined with 4 cycles of epirubicin and cyclophosphamide followed by 4 cycles of taxane and trastuzumab (P + EC-TH) regimen as neoadjuvant therapy for human epidermal growth factor receptor 2 (HER2) positive breast cancer and to investigate the predictive value of p53, p63, and epidermal growth factor receptor (EGFR) status for neoadjuvant efficacy.MethodsA total of 138 HER2-positive breast cancer patients who received neoadjuvant therapy and underwent surgery were included. Case group: 55 patients received P + EC-TH regimen. Control group: 83 patients received EC-TH regimen. The chi-square test, Fisher’s exact test, and logistic regression analysis were applied. The primary endpoint was total pathologic complete response (tpCR), and the secondary endpoints were breast pathologic complete response (bpCR), overall response rate (ORR), and adverse events (AEs).ResultsIn the case group, the tpCR rate was 63.64% (35/55), the bpCR rate was 69.09% (38/55), and the ORR was 100.00% (55/55). In the control group, the tpCR rate was 39.76% (33/83), the bpCR rate was 44.58% (37/83), and the ORR was 95.18% (79/83). The case group had significantly higher tpCR and bpCR rates than those of the control group (P < 0.05), but there was no significant difference in ORR (P > 0.05). The tpCR was associated with the status of estrogen receptor (ER), progesterone receptor (PR), and androgen receptor (AR), and the patients with any negative ER, PR, AR, or combined, were more likely to achieve tpCR than those with positive results (P < 0.05). The p53-positive patients were more likely to achieve tpCR and bpCR than p53-negative patients (P < 0.05). The incidence of hypokalemia and diarrhea in the case group was higher than that in the control group (P < 0.05). The AEs developed were all manageable, and no treatment-related death occurred.ConclusionThe efficacy and safety of the P + EC-TH regimen were verified by this study. The HER2-positive breast cancer patients treated with the EC-TH neoadjuvant regimen were more likely to achieve tpCR or bpCR if pyrotinib was administered simultaneously.

A multicenter single‐arm trial of neoadjuvant pyrotinib and trastuzumab plus chemotherapy for HER2‐positive breast cancer

AbstractThe objective of this multicenter, single‐arm trial (ChiCTR1900022293) was to explore the efficacy and safety of neoadjuvant therapy with epirubicin, cyclophosphamide, and pyrotinib followed by docetaxel, trastuzumab, and pyrotinib (ECPy‐THPy) in the treatment of patients with stage II–III HER2‐positive breast cancer. The present study enrolled patients with stage II–III HER2‐positive breast cancer. Epirubicin and cyclophosphamide were administrated for four 21‐day cycles, followed by four cycles of docetaxel and trastuzumab. Pyrotinib was taken orally once per day throughout the treatment period. The primary endpoint was total pathological complete response (tpCR, ypT0/is ypN0) rate in the modified intention‐to‐treat (mITT) population. In total, 175 patients were included. The tpCR rate was 68.6% (95% CI, 60.7–75.8%), while the objective response rate was 89.1%. In the post‐hoc subgroup analysis, no association between clinical characteristics and the tpCR rate was observed. The most common grade ≥3 adverse events were diarrhea (54.3%), followed by white blood cell count decreased (5.1%), and neutrophil count decreased (4.6%). In conclusion, the neoadjuvant regimen with ECPy‐THPy showed promising pathological response and clinical benefits with an acceptable safety profile in patients with stage II–III HER2‐positive breast cancer.

Nodal pCR and overall survival following neoadjuvant chemotherapy for node positive ER+/Her2- breast cancer.

The role of neoadjuvant chemotherapy (NAC) in node-positive (N+) ER+/HER2- breast cancer (BC) is debated, given low total pathologic complete response (pCR) rates. However, the rate and impact of nodal pCR is unknown. We sought to evaluate nodal pCR rates and the impact on overall survival (OS). Further, we sought to validate the association between nodal pCR with age and Ki67. We queried the National Cancer Database for cN + ER+/HER2- BC patients treated with NAC and surgery. Data from 2010 to 2018 were used to evaluate nodal pCR and OS, with multivariable Cox proportional hazards modeling for OS, as well as Ki67 for the years 2018-2019. From 2010 to 2018, we identified 19,611 cN + ER+/HER2- BC patients treated with NAC. While total pCR occurred in only 7.4%, nodal pCR rates were nearly double (14.3%). Nodal pCR (+/- breast pCR) was seen in 21.7% and associated with 5-year OS rate of 86.1% (95% CI: 84.9-87.4%) versus 77.1% (95% CI: 76.3-77.9%) in patients without nodal pCR (p < 0.001). On multivariable analysis, nodal pCR had better OS (adjusted HR 0.57, 95%CI 0.52-0.63, p < 0.001) across all age groups. Of 2,444 patients with available Ki67, those with age < 50 and Ki67 ≥ 20% had the highest nodal pCR at 31.6%. In cN + ER+/HER2- BC treated with NAC, nodal pCR is common, associated with age and Ki67, and prognostic for OS. These data strongly suggest that for cN + patients, eradication of nodal disease is critical for OS, and total pCR may not be the optimal measure of NAC benefit.

Efficacy comparisons of solvent-based paclitaxel, liposomal paclitaxel, nanoparticle albumin-bound paclitaxel, and docetaxel after neoadjuvant systemic treatment in breast cancer

PurposeThere are four kinds of taxanes: solvent-based paclitaxel (Sb-P), liposomal paclitaxel (Lps-P), nanoparticle albumin-bound paclitaxel (Nab-P), and docetaxel. This study aims to retrospectively evaluate the efficacy of different taxanes on neoadjuvant systemic treatment (NST) in breast cancer. MethodsPatients who were diagnosed with breast cancer and had received integral NST from August 2013 to April 2022 were enrolled. The efficacy was divided into total pathological complete response (total-pCR), breast pathological complete response (breast-pCR), and axillary pathological complete response (axillary-pCR) for in-depth analysis and discussion. ResultsThe choice of taxane was an independent risk factor for total-pCR and breast-pCR rates. The highest total-pCR and breast-pCR rates were found in the Nab-P group. The difference was not significant among all the taxanes in the axillary-pCR rate. ConclusionNab-P significantly improved the total-pCR and breast-pCR rates. It should be the first choice among taxanes in NST for breast cancer.

Neoadjuvant Pyrotinib plus Trastuzumab, Docetaxel, and Carboplatin in Early or Locally Advanced Human Epidermal Receptor 2-Positive Breast Cancer in China: A Multicenter, Randomized, Double-Blind, Placebo-Controlled Phase 2 Trial

Introduction: This multicenter, randomized, double-blind, placebo-controlled phase 2 trial compared the efficacy, and safety of adding pyrotinib to trastuzumab, docetaxel, and carboplatin versus placebo, trastuzumab, docetaxel, and carboplatin in Chinese patients with human epidermal receptor 2 (HER2)-positive early or locally advanced breast cancer (<ext-link ext-link-type="uri" xlink:href="http://ClinicalTrials.gov" xmlns:xlink="http://www.w3.org/1999/xlink">ClinicalTrials.gov</ext-link> identifier: NCT03756064). Methods: Sixty-nine women with HER2-positive early (T1-3, N0-1, M0) or locally advanced breast cancer (T2-3, N2 or N3, M0; T4, any N, M0) were recruited from October 1, 2019, to June 1, 2021. Before surgery, patients received 6 cycles of orally pyrotinib (400 mg once per day), trastuzumab (8-mg/kg loading dose and 6-mg/kg maintenance doses), docetaxel (75 mg/m²), and carboplatin (AUC = 6 mg/mL·min) or orally placebo, trastuzumab, and docetaxel, and carboplatin every 3 weeks. The primary end point was independent review committee-assessed total pathologic complete response rate. The 2-sided Cochran-Mantel-Haenszel test, stratified by age, hormone receptor status, tumor stage, nodal status, cTNM stage, and Ki-67 level was used to compare rates between treatment groups. Results: In total, 69 female patients were randomized (pyrotinib, 36; and placebo, 33; median age, 53 [31–69] years). In the intention-to-treat population, total pathologic complete response rates were 65.5% (19/29) in the pyrotinib group and 33.3% (10/30) in the placebo group (difference, 32.2%, p = 0.013). Diarrhea was been reported in 86.1% of patients (31/36) in the pyrotinib group as the most common adverse events (AEs) and 15.2% of patients (5/33) in the placebo group. But no grade 4 or 5 AEs were reported. Conclusion: Treatment with pyrotinib, trastuzumab, docetaxel, and carboplatin resulted in a statistically significant improvement in the total pathologic complete response rate versus placebo, trastuzumab, docetaxel, and carboplatin for the neoadjuvant treatment of HER2-positive early or locally advanced breast cancer in Chinese patients. Safety data were in line with the known pyrotinib safety profile and generally comparable between treatment groups.

Use of PLR and NLR to evaluate the efficacy and prognosis of neoadjuvant chemotherapy with lobaplatin in triple-negative breast cancer.

594 Background: Previously, we showed that addition of lobaplatin (L) to taxane (T) combined with anthracycline (E) could improve the pathological complete response (pCR) rate of neoadjuvant therapy for triple-negative breast cancer (TNBC) and lengthen long-term survival significantly, but the therapeutic markers of this regimen are not known. We investigated if the platelet/lymphocyte ratio (PLR) and neutrophil/lymphocyte ratio (NLR) could be used to predict the efficacy of the TEL regimen. Methods: Eighty-three patients with TNBC (stage I–III) who received TEL (docetaxel (T) at 75 mg/m2, epirubicin (E) at 80 mg/m2, and lobaplatin (L) at 30 mg/m2) from January 2014 to August 2019 were recruited. They received four cycles before surgery and two cycles after surgery. Patients were divided into four groups according to the mean values of the PLR (145.71) and NLR (2.74): high PLR (PLR+), low PLR (PLR−), high NLR (NLR+), and low NLR (NLR−). Differences in the total pathologic complete response (tpCR) rate, event-free survival (EFS), and overall survival (OS) were analyzed in different groups of patients using the TEL protocol. Results: The tpCR rate in the PLR− group was 49.0% (25/51), which was significantly higher than that in the PLR+ group (25.0% (8/32); odds ratio (OR) = 2.885, 95% confidence interval (CI) = 1.093–7.612, P = 0.032). The tpCR rate in the NLR− group was 49.1% (26/53), which was significantly higher than that in the NLR+ group (23.3% (7/30); OR = 3.164, 95% CI = 1.161–8.626, P = 0.024). The tpCR rate of the PLR−NLR− group was 53.7% (22/41), which was significantly higher than that of the PLR+/NLR+ group (26.1% (11/42), with a high proportion of any index (OR = 3.263, 95% CI = 1.298–8.204, P = 0.012). The median duration of follow-up was 69 months. EFS and OS in the NLR− group were significantly longer than those in the NLR+ group (hazard ratio (HR) = 5.946, 95% CI = 1.526–23.169, P = 0.010 for EFS; HR = 7.803, 95% CI = 1.565–38.907, P = 0.012 for OS). Five-year EFS was 95.1% for the PLR−NLR− group, 91.0% for the PLR+NLR− group, 76.0 for the PLR+NLR+ group, and 59.1% for the PLR−NLR+ group. Compared with the PLR+/NLR+ group, patients in the PLR-NLR- group had the longest EFS (P = 0.002). Conclusions: PLR and NLR could be used to predict the efficacy of neoadjuvant therapy with taxane, anthracycline, and lobaplatin regimen in TNBC, and the low-proportion group had a higher tpCR rate and a better long-term prognosis. Clinical trial information: ChiCTR-TRC-14005019 .

Taxane combined with lobaplatin or anthracycline for neoadjuvant treatment of triple-negative breast cancer: A single-center, randomized, controlled, phase-II clinical study.

593 Background: Previously, we showed that addition of lobaplatin (L) to taxane combined with anthracycline could improve the pathologic complete response (pCR) rate and lengthen survival significantly if employed as neoadjuvant therapy in patients with triple-negative breast cancer (TNBC). We evaluated the efficacy and safety of neoadjuvant chemotherapy of taxane (T) combined with lobaplatin (L) or anthracycline (E) for patients with TNBC. Methods: Ninety-five patients with TNBC (stage I–III) who had not undergone any type of treatment were divided randomly into two groups: TL (docetaxel at 75 mg/m2 and lobaplatin at 30 mg/m2, D1, one cycle = 21 days, a total of six cycles) or TE (docetaxel at 75 mg/m2 and epirubicin at 80 mg/m2, D1, one cycle = 21 days, a total of 6 weeks or epirubicin at 80 mg/m2 and cyclophosphamide at 600 mg/m2, sequential docetaxel at 75 mg/m2, D1, one cycle = 21 days, a total of eight cycles). Efficacy was evaluated every two cycles. The final surgical procedure was completed after fulfillment of neoadjuvant chemotherapy. The primary endpoint was the total pathologic complete response (tpCR) rate. The secondary endpoints were the objective response rate (ORR), safety, event-free survival (EFS), and overall survival (OS). The exploratory endpoint was biomarker analysis. Results: From June 2019 to November 2022, 97 patients were screened. Finally, 95 patients were enrolled. The median age of the study cohort was 49 years. Nine patients (9.5%) had stage-I disease, 61 patients (64.2%) had stage II, and 25 patients (26.3%) had stage III. Sixty-five patients (68.4%) had Ki67 ≥40% and 30 patients (31.6%) had Ki67 &lt; 40%. Seventy patients (73.7%) were cytokeratin (CK)5/6+ and 25 patients (26.3%) were CK5/6−. Of 95 patients, 47 were in the TL group and 48 in the TE group. The tpCR rate in the TL group was 46.8% (22/47), which was significantly higher than that in the TE group (22.9% (11/48); odds ratio (OR) = 2.960, 95% confidence interval (CI) = 1.223–7.164, P = 0.016). The ORR in the TL group was 95.7% (45/47), which was significantly higher than that in the TE group (75.0% (36/48); OR = 27.500, 95% CI = 1.576–35.683, P = 0.011). The prevalence of grade III/IV neutropenia in the TE group was 41.0% (9/22), which was significantly higher than that in the TL group (7.7% (2/26); OR = 8.308, 95% CI = 1.557–44.320, P = 0.013). There was no significant difference in the prevalence of other adverse reactions between the two groups. Conclusions: In the neoadjuvant treatment of TNBC, the TL regimen had a higher tpCR rate and ORR than those of the TE regimen, and was safer. Clinical trial information: ChiCTR1900023776 .

Neoadjuvant pyrotinib plus trastuzumab, dalpiciclib, and letrozole for triple-positive breast cancer: A pilot trial.

e12603 Background: Our previous MUKDEN 01 study showed a promising total pathological complete response (tpCR) rate of 30.4% with neoadjuvant pyrotinib plus dalpiciclib (cyclin dependent kinase 4/6 inhibitor) and letrozole in patients with triple-positive breast cancer (TPBC), but the efficacy still needs improvement. This pilot study explored the efficacy and safety of adding trastuzumab to this neoadjuvant regimen in TPBC. Methods: Patients received five 28-day cycles of pyrotinib (320 mg once daily), dalpiciclib (125 mg once daily on days 1-21) and letrozole (2.5 mg once daily), plus six 21-day cycles of trastuzumab (8 mg/kg loading dose followed by 6 mg/kg maintenance dose on day 1), followed by surgery. The primary endpoint was tpCR (ypT0/is, ypN0) rate. Secondary endpoints were objective response rate (ORR), breast pathological complete response (bpCR; ypT0/is) rate, residual cancer burden (RCB), change in Ki-67 level from baseline to surgery, and safety. Results: Between February 16, 2022 and June 2, 2022, 12 patients were enrolled. Seven (58%; 95% CI, 27.7-84.8) patients achieved tpCR and bpCR. The rate of RCB 0-I was 75% (95% CI, 46.8-91.1%). ORR was 92% (95% CI, 64.6-98.5%). Mean Ki-67 level was significantly reduced from 45.0% (95% CI, 19.5% - 70.5%) at baseline to 17.2% (95% CI, 0.7% - 33.7%) after neoadjuvant therapy (P&lt;0.05). The most common grade 3 adverse events were diarrhea (4 [33%]) and decreased neutrophil count (3 [25%]). No grade 4 events or treatment-related deaths occurred. Conclusions: This four-drug neoadjuvant regimen shows promising pathological response in patients with TPBC, with an acceptable safety profile. The results warranted further validation. Clinical trial information: NCT05228951 .

Total neoadjuvant therapy in rectal cancer: a network meta-analysis of randomized trials.

To assess the efficacy of total neoadjuvant therapy (TNT) for rectal carcinoma in comparison with conventional chemoradiotherapy (CRT). A systematic review was performed according to the PRISMA guidelines. A Bayesian network meta-analysis was done using NetMetaXL and WinBUGS. This study was registered in PROSPERO on March 3, 2022 (No. CRD-42022307867). Outcomes of 2,719 patients from 10 randomized trials between 2010 and 2022 were selected. Of these 1,191 (44%) had conventional long-course CRT (50-54 Gy) and capecitabine, 506 (18%) had induction chemotherapy followed by CRT (50-54 Gy) and capecitabine (iTNT), 230 (9%) had long-course CRT (50-54 Gy) followed by consolidation chemotherapy (cTNT), and 792 (29%) undergone modified short-course radiotherapy (25 Gy) with subsequent chemotherapy (mTNT). Total pathologic complete response (pCR) was 20% in the iTNT group, 21% in the mTNT group, 22% in the cTNT group, and 12% in the CRT group. Statistically significant difference in pCR rates was detected when comparing iTNT with CRT (odds ratios [OR], 1.76; 95% credible interval [CrI], 1.06-2.8), mTNT with CRT (OR, 1.90; 95% CrI, 1.25-2.74), and cTNT with CRT groups (OR, 2.54; 95% CrI, 1.26-5.08). No differences were found in R0 resection rates. No significant difference was found in long-term outcomes. The early administration of systemic chemotherapy in the TNT regimen has improved short-term outcomes, though long-term results are underreported. Randomized trials with survival as the endpoint are necessary to evaluate the possible advantages of TNT modes.

Abstract P2-01-07: Combination of pyrotinib with trastuzumab, taxanes and platinum as neoadjuvant therapy in patients with HER2-positive early or locally advanced breast cancer: a multicenter phase II trial

Abstract Background: Pyrotinib (an irreversible pan-ErbB inhibitor) plus capecitabine have shown clinically and statistically meaningful progression-free survival and overall survival benefits with acceptable tolerability in patients with HER2-positive metastatic breast cancer in phase 3 trials. In this study, we assessed the efficacy and safety of neoadjuvant pyrotinib plus trastuzumab, taxanes and platinum in women with HER2-positive early or locally advanced breast cancer. Methods: In this multicenter, single-arm, phase II trial (ChiCTR2000039286), treatment-naive patients with early or locally advanced (T2-3, N0-3, M0) breast cancer received pyrotinib 400 mg once daily, plus trastuzumab (8 mg/kg loading dose and 6 mg/kg maintenance dose), docetaxel (75 mg/m2) or nab-paclitaxel (125 mg/m2), and carboplatin (AUC=5-7) on day 1 of each 21-day cycle for 6 cycles before surgery. All patients also received 1-year adjuvant pyrotinib combined with trastuzumab after surgery. The primary endpoint of the study was total pathological complete response (tpCR, ypT0/is ypN0) rate. The secondary endpoints were breast pathological complete response (bpCR) rate, objective response rate, adverse events (AEs) and invasive disease-free survival. Results: Between October 2020 and March 2022, a total of 35 patients were enrolled from 7 sites. By the data cut-off date on June 29, 2022, two patients withdrew from the study, and one received other anti-tumor therapies. Thirty-two patients received neoadjuvant therapy and surgery (modified intention-to-treat [mITT] population), and 30 of whom completed the 6-cycle neoadjuvant therapy (per-protocol [PP] population). The local pathologist-assessed tpCR rate was 59.4% (19/32) and 60.0% (18/30) in the mITT and PP populations, and bpCR rate was 65.6% (21/32) and 66.7% (20/30) in the mITT and PP populations, respectively. The tpCR rate was 68.8% (11/16) among patients with hormone receptor-negative disease and 50.0% (8/16) among those with hormone receptor-positive disease in the mITT population. Of 30 patients with preoperative imaging assessments, 26 (86.7%) achieved an objective response. Treatment-related AEs (TRAEs) were reported in 34 (97.1%) of 35 patients, with the most common being diarrhea (82.9%) and platelet decreased (48.6%). The most common grade ≥3 TRAEs were diarrhea (25.7%), platelet decreased (8.6%), neutropenia (8.6%), vomiting (5.7%), and alanine aminotransferase increased (5.7%). No grade 4 or 5 diarrhea events occurred. Conclusions: This study showed similar efficacy with previous reports, neoadjuvant pyrotinib plus trastuzumab-based chemotherapy exhibits promising efficacy and manageable toxicity in patients with HER2-positive early or locally advanced breast cancer. Citation Format: Hao Zhou, Lei Wang, Lei Wang, Zhaoji Guo. Combination of pyrotinib with trastuzumab, taxanes and platinum as neoadjuvant therapy in patients with HER2-positive early or locally advanced breast cancer: a multicenter phase II trial [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-01-07.

Abstract OT2-22-01: Epirubicin, cyclophosphamide and pyrotinib followed by docetaxel, trastuzumab and pyrotinib as neoadjuvant therapy for stage II-III HER2-positive breast cancer: a single-arm, multicenter phase 2 trial

Abstract Background: Dual HER2 targeted therapy with pyrotinib (a tyrosine kinase inhibitor targeting HER1, HER2, and HER4) and trastuzumab plus chemotherapy has been approved as neoadjuvant therapy for patients with HER2-positive breast cancer in China based on the results from phase 3 PHEDRA study. However, the optimal chemotherapy partner still needs exploration. This multicenter phase 2 trial (ChiCTR1900022293) aimed to investigate the efficacy and safety of epirubicin, cyclophosphamide and pyrotinib followed by docetaxel, trastuzumab and pyrotinib (ECP-THP) as neoadjuvant therapy for patients with stage II-III HER2-positive breast cancer. Methods: Patients received intravenous epirubicin (90 mg/m2) and cyclophosphamide (600 mg/m2) on day 1 of each cycle for four 21-day cycles, followed by intravenous docetaxel (75 mg/m2) and trastuzumab (8 mg/kg loading dose, followed by 6 mg/kg) on day 1 for 4 cycles. Pyrotinib 400 mg was given orally once daily throughout the neoadjuvant therapy period. Surgery was performed within 16-20 days after the last neoadjuvant therapy. The primary endpoint was total pathological complete response (tpCR, ypT0/is ypN0) rate. Results: Between May 2020 and May 2022, a total of 175 patients enrolled. As of May 31, 2022, 144 patients had undergone surgery; the median age was 51 years (range, 26-67). Sixty-seven (46.5%) of 144 patients had hormone receptor (HR)-negative disease, and 77 (53.5%) had HR-positive disease. The tpCR rate was 67.4% (97/144; 95%CI, 59.3%-74.5%). Patients with HR-negative disease had numerically higher tpCR rate than those with HR-positive disease (73.1% [95%CI, 61.5%-82.3%] vs. 62.3% [95%CI, 51.2%-72.3%]), but without statistical significance (P=0.230). Miller-Payne grade 4 and 5 pathological responses were found in 22 (15.3%) and 97 (67.4%) of 144 patients, respectively. Regarding clinical response to neoadjuvant therapy before surgery, 31 (21.5%) of 144 patients achieved complete response and 99 (68.8%) achieved partial response, with an objective response rate of 90.3% (95%CI, 84.3%-94.1%). Of 161 patients with available safety data, the most common grade ≥3 adverse events included diarrhea (57.1%), white blood cell count decreased (8.7%), and neutrophil count decreased (5.6%). No treatment-related deaths occurred. Conclusions: Patients with stage II-III HER2-positive breast cancer show favorable clinical and pathological response to this ECP-THP neoadjuvant regimen, with an acceptable safety profile. Citation Format: Qiyun Shi, Xiaowei Qi, Peng Tang, Linjun Fan, Li Chen, Shushu Wang, Guozhi Zhang, Mengyuan Wang, Hongying Che, Pengwei Lv, Dejie Chen, Jinhui Hu, Qiuyun Li, Yanwu Zhang, Qiao Yu, Kunxian Yang, Yuan Zhong, Chuang Chen, Zemin Zhou, Liyuan Qian, Jingwei Zhang, Mingde Ma, Yi Sun, Jiangbo Liu, Yi Zhang, Jun Jiang. Epirubicin, cyclophosphamide and pyrotinib followed by docetaxel, trastuzumab and pyrotinib as neoadjuvant therapy for stage II-III HER2-positive breast cancer: a single-arm, multicenter phase 2 trial [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT2-22-01.