A proof-of-concept study of LXP5268 as an add-on neoadjuvant chemotherapy in patients with early-stage triple-negative breast cancer.

Abstract

e12607 Background: Triple-negative breast cancer (TNBC) is a heterogeneous and aggressive subtype characterized by a high risk of mortality and a poor prognosis. The 2019 ASCO and St. Gallen International Consensus Guidelines strongly recommend neoadjuvant chemotherapy (NACT) for early-stage TNBC. Previous studies indicated that NACT improved overall and disease-free survival in early-stage TNBC. LXP5268, a drug in the 505(b)(2) category, has demonstrated efficacy in reducing tumor size in animal models. Our study aims to assess whether combining LXP5268 with NACT enhances anti-tumor efficacy and tumor shrinkage rates in early-stage TNBC patients. Methods: Enrolled patients had untreated stage II-III TNBC. NACT consisted of docetaxel every 3 weeks for four cycles, followed by epirubicin plus cyclophosphamide every 3 weeks for an additional four cycles (24 weeks total). In the LXP5268 add-on NACT (LXP5268+NACT) group, patients took LXP5268 orally once daily with NACT. After treatment, we analyzed tumor objective response rate (ORR), shrinkage rate by CT images, and adverse events (AEs) diagnosed by the principal investigator. Whole-exome sequencing (WES) was performed on 6 subjects in the LXP5268+NACT group, identifying potential germline variants and biomarkers, clinically interpreted following ACMG/AMP 2015 guidelines. Results: Both groups had similar baseline characteristics. LXP5268+NACT subjects (54.8 ± 7.2 years) and NACT subjects (59.3 ± 9.8 years) showed significant age differences ( p<0.001). The ORR was 100% in both the LXP5268+NACT group (3 pathological complete response, pCR and 4 pathological partial response, pPR) and NACT group (6 pPR). The tumor shrinkage rate was significantly higher in the LXP5268+NACT group at 77.3% ± 21.8 compared to 43.4% ± 12.8 in the NACT group ( p< 0.001). Moreover, subjects in the LXP5268+NACT group with a tumor reduction exceeding 50% surpassed those in the NACT group. AEs included neutropenia (85.7%), constipation (66.7%), and insomnia (66.7%), all grade 1. Interestingly, mutation in XIRP2 correlated with higher tumor shrinkage rate. Conclusions: LXP5268 combined with NACT was more effective than NACT alone for early-stage TNBC, without increasing AEs. These results highlight LXP5268's potential in TNBC therapy. Previous studies indicated XIRP2 mutations in metastatic breast cancer. LXP5268+NACT achieved pCR in XIRP2-mutated patients. Future clinical trials will expand to enhance result verification accuracy. Clinical trial information: CMUH106-REC3-145.