In cancer patients, tumor gene mutations contribute to drug resistance and treatment failure. In patients with metastatic breast cancer (MBC), these mutations increase after multiline treatment, thereby decreasing treatment efficiency. The aim of this study was to evaluate gene mutation patterns in MBC patients to predict drug resistance and disease progression. A total of 68 MBC patients who had received multiline treatment were recruited. Circulating tumor DNA (ctDNA) mutations were evaluated and compared among hormone receptor (HR)/human epidermal growth factor receptor 2 (HER2) subgroups. The baseline gene mutation pattern (at the time of recruitment) varied among HR/HER2 subtypes. BRCA1 and MED12 were frequently mutated in triple negative breast cancer (TNBC) patients, PIK3CA and FAT1 mutations were frequent in HR+ patients, and PIK3CA and ERBB2 mutations were frequent in HER2+ patients. Gene mutation patterns also varied in patients who progressed within either 3 months or 3-6 months of chemotherapy treatment. For example, in HR+ patients who progressed within 3 months of treatment, the frequency of TERT mutations significantly increased. Other related mutations included FAT1 and NOTCH4. In HR+ patients who progressed within 3-6 months, PIK3CA, TP53, MLL3, ERBB2, NOTCH2, and ERS1 were the candidate mutations. This suggests that different mechanisms underlie disease progression at different times after treatment initiation. In the COX model, the ctDNA TP53 + PIK3CA gene mutation pattern successfully predicted progression within 6 months. ctDNA gene mutation profiles differed among HR/HER2 subtypes of MBC patients. By identifying mutations associated with treatment resistance, we hope to improve therapy selection for MBC patients who received multiline treatment.

Background: Pyrotinib, an irreversible pan-ERBB inhibitor, has shown promising antitumour activity, and acceptable tolerability. This research was conducted to evaluate the actual use and effectiveness of pyrotinib in China, therefore, contributed to solve the problem of real-world data scarcity.Methods: In this retrospective study, 168 patients who received pyrotinib treatment for HER2-positive metastatic breast cancer (MBC) in Hunan Province from June 2018 to August 2019 were included. Progression-free survival (PFS), tumor mutation burden (TMB), and drug-related adverse events (AEs) after pyrotinib administration were analyzed.Results: The median PFS (mPFS) time in the 168 participants was 8.07 months. The mPFS times in patients with pyrotinib in second-line therapy (n = 65) and third-or-higher-line therapy (n = 94) were 8.10 months and 7.60 months, respectively. Patients with brain metastases achieved 8.80 months mPFS time. In patients with pyrotinib in third-or-higher-line therapy, patients who had previously used lapatinib still got efficacy but showed a shorter mPFS time (6.43 months) than patients who had not (8.37 months). TMB was measured in 28 patients, K-M curve (P = 0.0024) and Multivariate Cox analysis (P = 0.0176) showed a significant negative association between TMB and PFS. Diarrhea occurred in 98.2% of participants (in any grade) and 19.6% in grade 3–4 AEs.Conclusion: Pyrotinib is highly beneficial to second-or-higher-line patients or HER2-positive MBC patients with brain metastases. Pyrotinib seems to be a feasible strategy both in combination of chemotherapeutic drugs or as a replacement of lapatinib if diseases progressed. TMB could be a potential predictor for evaluating pyrotinib's effectiveness in HER2-positive MBC.

Circulating tumor DNA (ctDNA) has good clinical guiding value for metastatic breast cancer (MBC) patients. This study aimed to apply a novel genetic analysis approach for therapeutic prediction based on ctDNA alterations. This nonrandomized, multicenter study recruited 223 MBC patients (NCT05079074). Plasma samples were collected for target-capture deep sequencing of ctDNA at baseline, after the 2nd cycle of treatment, and when progressive disease (PD) was evaluated. Samples were categorized into four levels according to the number of ctDNA alterations: level 1 (no alterations), level 2 (1–2 alterations), level 3 (3–4 alterations) and level 4 (≥5 alterations). According to ctDNA alteration level and variant allele frequency (VAF), a novel ctDNA-level Response Evaluation Criterion in Solid Tumors (ctle-RECIST) was established to assess treatment response and predict progression-free survival (PFS). The median PFS in level 1 (6.63 months) patients was significantly longer than that in level 2–4 patients (level 2: 5.70 months; level 3–4: 4.90 months, p < 0.05). After 2 cycles of treatment, based on ctle-RECIST, the median PFS of level-based disease control rate (lev-DCR) patients was significantly longer than that of level-based PD (lev-PD) patients [HR 2.42 (1.52–3.85), p < 0.001]. In addition, we found that ctDNA level assessment could be a good supplement to radiologic assessment. The median PFS in the dual-DCR group tended to be longer than that in the single-DCR group [HR 1.41 (0.93–2.13), p = 0.107]. The ctDNA alteration level and ctle-RECIST could be novel biomarkers of prognosis and could complement radiologic assessment in MBC.

Eribulin mesylate is a novel, nontaxane, microtubule dynamics inhibitor. In this study, we assessed the efficacy and safety of eribulin versus eribulin plus the oral small-molecule tyrosine kinase inhibitor anlotinib in patients with locally recurrent or metastatic breast cancer. In this single-center, open-label, phase II clinical study (NCT05206656) conducted in a Chinese hospital, patients with human epidermal growth factor receptor 2 (HER2)-negative, locally recurrent or metastatic breast cancer previously treated with anthracycline- or taxane-based chemotherapy were randomized (1 : 1) to receive eribulin alone or in combination with anlotinib. The primary efficacy endpoint was investigator-assessed progression-free survival (PFS). From June 2020 to April 2022, a total of 80 patients were randomly assigned to either eribulin monotherapy or eribulin plus anlotinib combination therapy, with 40 patients in each group. The data cut-off was 10 August 2022. The median PFS was 3.5 months [95% confidence interval (CI) 2.8-5.5 months] for eribulin and 5.1 months (95% CI 4.5-6.9 months) for eribulin plus anlotinib (hazard ratio = 0.56, 95% CI 0.32-0.98; P = 0.04). The objective response rates were 32.5% versus 52.5% (P = 0.07), respectively, and disease control rates were 67.5% versus 92.5% (P = 0.01), respectively. Patients <50 years of age, with an Eastern Cooperative Oncology Group performance status score of 0, visceral metastasis, number of treatment lines of four or more, hormone receptor negative (triple-negative), and HER2 low expression appeared to benefit more from combined treatment. The most common adverse events in both groups were leukopenia (n = 28, 70.0%, patients in the eribulin monotherapy group versus n = 35, 87.5%, patients in the combination therapy group), aspartate aminotransferase elevations (n = 28, 70.0%, versus n = 35, 87.5%), neutropenia (n = 25, 62.5%, versus n = 31, 77.5%), and alanine aminotransferase elevations (n = 25, 62.5%, versus n = 30, 75.0%). Eribulin plus anlotinib can be considered an alternative treatment option for HER2-negative locally advanced or metastatic breast cancer.

Objective: We aimed to investigate the pharmacokinetics, safety, efficacy, and immunogenicity of different dosing regimens (weekly and every three weeks) of inetetamab in combination with vinorelbine in human epidermal growth factor receptor 2 (HER2)+ patients with metastatic breast cancer who had received one or more chemotherapy regimens. Methods: HER2+ patients with metastatic breast cancer who had received one or more chemotherapy regimens were included. Eligible patients received inetetamab administered weekly or every three weeks in combination with vinorelbine injection chemotherapy. Pharmacokinetics, safety, efficacy, and immunogenicity were compared between the groups. Results: Sixty HER2+ patients were randomized into a single-week administration group ( n = 29) and a three-week administration group ( n = 31). After the final dose in the single-week administration group and the three-week administration group, the mean C_max values were 79.773 μg/mL and 146.083 μg/mL; the mean C_min values were 30.227 μg/mL and 11.926 μg/mL; the mean AUC_tau values were 7328.443 μg·h/mL and 22647.101 μg·h/mL; and the mean C_av values were 43.622 μg/ mL and 44.935 μg/mL, respectively. The best overall response (BOR) rates at 24 weeks and unconfirmed BOR rates at 24 weeks were both 40.7% in the single-week dosing group and 40.7% in the three-week dosing group, and the 24-week confirmed disease control rates (DCRs) were 88.9% and 81.5%, respectively. The incidence of adverse events (AEs) was generally consistent across all levels. Conclusion: There were slight differences in the mean C_max, C_min, AUC_tau and C_av between the three-week dosing group and the single-week dosing group, and the mean steady-state concentrations of C_av were comparable; however, there were no differences in efficacy, safety or immunogenicity between the two groups.

Background: Human epidermal growth factor receptor 2 (HER2) targeted therapy combined with endocrine therapy has been recommended as an alternative treatment strategy for patients with hormone receptor (HR)-positive, HER2-positive metastatic breast cancer (MBC). This study aimed to evaluate the role of pyrotinib, an oral pan-HER irreversible tyrosine kinase inhibitor, in combination with letrozole for patients with HR-positive, HER2-positive MBC. Methods: In this multi-center, phase II trial, HR-positive and HER2-positive MBC patients who were not previously treated for metastasis disease were enrolled. Patients received daily oral pyrotinib 400 mg and letrozole 2.5 mg until disease progression, unacceptable toxicity, or withdrawal of consent. The primary endpoint was the clinical benefit rate (CBR) assessed by an investigator according to the Response Evaluation Criteria in Solid Tumors version 1.1. Results: From November 2019 to December 2021, 53 patients were enrolled and received pyrotinib plus letrozole. As of August 2022, the median follow-up duration was 11.6 months (95% confidence interval [CI], 8.7–14.0 months). The CBR was 71.7% (95% CI, 57.7–83.2%), and the objective response rate was 64.2% (95% CI, 49.8–76.9%). The median progression-free survival was 13.7 months (95% CI, 10.7–18.7 months). The most common treatment-related adverse event of grade 3 or higher was diarrhea (18.9%). No treatment-related deaths were reported, and one patient experienced treatment discontinuation due to adverse event. Conclusions: Our preliminary results suggested that pyrotinib plus letrozole is feasible for the first-line treatment of patients with HR-positive and HER2-positive MBC, with manageable toxicities. Trial registration: ClinicalTrials.gov, NCT04407988.