The efficiency of anlotinib in osteosarcoma with chemoresistance: Exploratory therapy based on PDX models and next-generation sequencing.

Abstract

11527 Background: It’s urgent to find a new approach for the treatment of progressed osteosarcoma in neoadjuvant chemotherapy. Using patient-derived xenograft (PDX) models and next-generation sequencing (NGS), we have explored the efficiency of anlotinib in these patients. Methods: Frozen osteosarcoma tissues were used to establish PDX models. Ten samples of each PDX model were randomized to treatment or control group. The treatment group were gavaged at a volume of 0.1 ml/10g body weight for 4 weeks, while the control group were administered with vehicle at the same dose orally. Tumor volume and body weight were measured every 3 days, and the tumour were removed and weighed after 28 days. The number of mitotic cells and tumor necrosis rate were detected by Hematoxylin-Eosin (HE) staining. Immunohistochemistry (IHC) was used to evaluate the number of apoptotic cells and the expression of VEGFR-2, PDGFR-β, FGFR-1, c-Kit and their phosphorylated proteins, CD 31. Additionally, patients who had progressed during neoadjuvant chemotherapy (NAC) were treated with combination of anlotinib. After four cycles NAC, we performed salvage surgery and maintained with anlotinib. The change of tumor size was evaluated for tumor response. We used IHC and NGS to analyze the expression of drug targets. Results: 21 PDX models were established successfully from 43 samples. Tumor specimens from patients, who had pulmonary metastasis, local recurrence or chemoresistance, were easier to establish PDX models (P < 0.001, P = 0.046, P = 0.013). Six models were selected randomly for anlotinib. After anlotinib administration, the tumor inhibition rates were 18.82%, 45.98%, 85.86%, 83.38%, 84.57% and 86.42%. Anlotinib could not only inhibit the mitosis, induce tumor cell apoptosis and necrosis, but also decrease the expression of drug targets. The expression of VEGFR-2, PDGFR-β and CD31 were positively associated with tumor response. Five patients had received anlotinib during NAC. Four patients had tumor regression (69.4%, 28%, 19%, 8.7%), including two with high expression of VEGFR-2 mRNA or/and PDGFR-β and one with medium expression. Conclusions: Based on the results of PDX models and NGS, we suggested that osteosarcoma with high expression of VEGFR-2 or/and PDGFR-β was sensitive to anlotinib, which was alternative for patients progressed during NAC.