Background To evaluate whether the depth of response (DepRe) and early tumor shrinkage (ETS) are predictive factors of clinical outcomes in HER2-positive metastatic breast cancer (mBC) patients treated with trastuzumab. Methods We performed a retrospective study of 100 HER2-positive mBC patients who received trastuzumab combined with chemotherapy as first-line treatment. ETS and DepRe were calculated. We employed Youden’s index to determine the optimal cutoff value of ETS and DepRe for predicting progression-free survival (PFS) and overall survival (OS). We used Kaplan–Meier analysis, Log-rank tests, and Cox proportional hazards regression models to evaluate the impacts of ETS and DepRe on clinical outcomes. Results The optimal cutoff values were 30% for ETS and 40% for DepRe; ETS and DepRe were observed in 51.0% (51/100) and in 56.0% (56/100) of patients, respectively. Both ETS≥30% and DepRe≥40% were significant tumor-size metrics for predicting PFS (ETS: median 1.43 vs 0.69 years, hazard ratio [HR] = 0.384; 95% confidence interval [CI]: 0.245 to 0.601; P =0.000030; DepRe: median 1.43 vs 0.59 years, HR = 0.390; 95% CI: 0.250 to 0.609; P =0.0000034), but only DepRe≥40% was a significant predictor for OS (median 4.02 vs 3.07 years, HR = 0.484; 95% CI: 0.255 to 0.919; P = 0.027). Multivariate analyses also identified DepRe as an independent prognostic factor for PFS (HR = 0.52; 95% CI: 0.29 to 0.93; P = 0.028) and OS (HR=0.37; 95% CI:0.15 to 0.90; P = 0.029). Conclusion ETS≥30% and DepRe≥40% were significant predictors of better clinical outcomes in mBC patients treated with first-line trastuzumab-based chemotherapy. Further validation in prospective trials with larger patient populations is needed.

e12602 Background: Triple negative breast cancer (TNBC) has the traits of early onset, high malignancy and no effective molecular targets to act on, neoadjuvant chemotherapy is recommended as the preferred treatment for locally advanced TNBC with highly recurrence risk. The addition of platinum-based agents to conventional taxanes regimens in locally advanced TNBC can significantly improve pathological complete response (pCR) rate. Anti-angiogenic drugs are currently one of the few targeted therapies that have achieved efficacy in TNBC. Apatinib, an inhibitor of VEGFR2, shows significant antitumor activity in the patients with breast cancer. Methods: Pathologically confirmed TNBC patients with clinical stage I-IIIC (per AJCC 8th ed) with no previous surgery or radio-chemotherapy treatment were enrolled in our center from September 2018 to June 2020. Enrolled patients received 4-8 neoadjuvant treatment cycles of apatinib 250mg per day + paclitaxel 175mg/m2 d1 + carboplatin AUC = 4 d2 q14d (Apa+TC), followed by sequential surgery. Enrolled patients who underwent surgery were matched with TNBC patients received paclitaxel and carboplatin intense regimen (TC) contemporarily in our center by propensity score matching (PSM). pCR in breast and axilla (ie. ypT0/Tis ypN0) was the primary endpoint. Objective response rate (ORR), disease control rate (DCR), event-free survival (EFS), overall survival (OS) and adverse events (AEs) are secondary endpoints. Results: 25 locally advanced TNBC patients were enrolled for neoadjuvant therapy of Apa+TC. In radiological evaluation, 2 patients achieved CR, 20 patients achieved PR, 3 patients achieved SD, which indicated an ORR of 88% and a DCR of 100%. 23 of 25 enrolled patients underwent surgery, with a pCR rate of 60.87% (95%CI: 38.54%-80.29%). 69 patients who were treated by TC before surgery were matched by PSM based on baseline stage T and stage N features. A significant higher pCR rate was achieved in Apa+TC arm compared with TC alone (60.87% vs. 30.43%, respectively, P = 0.009). Similar incidence of AEs was observed between two arms. The main AEs were hematologic toxicities fatigue, digestive canal symptoms, transaminase elevation and peripheral neurotoxicity in Apa+TC arm. Grade III-IV AEs included granulocytopia (14/25), thrombocytopenia (4/25), anaemia (3/25), fatigue (1/25), hypertension (1/25) and arrhythmia (1/25). Meanwhile, apatinib-related AEs, including hypertension, proteinuria, and hand-and-foot syndrome, were mild. Due to the limited time, the survival follow-up is still in progress. Conclusions: Apatinib combined with paclitaxel and carboplatin intensive regimen achieved a better efficacy and manageable adverse events in neoadjuvant chemotherapy for locally advanced TNBC, which might be a promising strategy in the treatment of locally advanced TNBC. Clinical trial information: NCT03735082.

BackgroundCurrently, there are no standard regimens for metastatic breast cancer patients (MBC) who have failed ≥ 3 chemotherapy treatments. The aim of this study was to assess whether weekly low‐dose bevacizumab‐based regimens were well tolerated and would improve efficacy in MBC patients who had failed numerous therapies.MethodsSeventeen patients with MBC who were heavily pretreated with a median of five regimens of therapy (range 1–10) between 2012 and 2016 were included in the analysis. Bevacizumab was administered at a dose of 100 mg intravenously once a week combined with one or two types of chemotherapeutic drugs until confirmed disease progression or an intolerable adverse event was observed. Patient characteristics, objective response rate, clinical benefit rate, progression‐free survival, and toxicity were assessed.ResultsAll 17 patients had been pretreated with taxane‐based and anthracycline‐based chemotherapy. Weekly low‐dose bevacizumab combined with one or two types of chemotherapeutic drugs, which had usually not been previously used (e.g. etoposide, irinotecan, pemetrexed, methotrexate, and nab‐paclitaxel), was administered. Three patients achieved a partial response, while one had stable disease for > 24 weeks, and the clinical benefit rate was 23.5%. Median progression‐free survival was 3.4 months (95% confidence interval 2.0–4.8). The most common hematological adverse events were neutropenia, anemia, and thrombocytopenia. Bevacizumab‐related adverse events included grade 1 bleeding (17.6%) and grade 2 hypertension (5.9%).ConclusionsWeekly low‐dose bevacizumab combined with chemotherapy shows a relatively favorable clinical response and tolerable toxicity, providing a feasible option for heavily pretreated MBC patients.