Safety and Clinical Activity of SHR7390 Monotherapy or Combined With Camrelizumab for Advanced Solid Tumor: Results From Two Phase I Trials.

BACKGROUND: SHR7390 is a novel, selective MEK1/2 inhibitor. Here, we report results from two phase I trials conducted to evaluate the tolerability, safety and antitumor activity of SHR7390 monotherapy for advanced solid tumors and SHR7390 plus camrelizumab for treatment-refractory advanced or metastatic colorectal cancer (CRC). PATIENTS AND METHODS: Patients received SHR7390 alone or combined with fixed-dose camrelizumab (200 mg every 2 weeks) in an accelerated titration scheme to determine the maximum tolerated dose (MTD). A recommended dose for expansion was determined based on the safety and tolerability of the dose-escalation stage. The primary endpoints were dose limiting toxicity (DLT) and MTD. RESULTS: In the SHR7390 monotherapy trial, 16 patients were enrolled. DLTs were reported in the 1.0 mg cohort, and the MTD was 0.75 mg. Grade ≥3 treatment-related adverse events (TRAEs) were recorded in 4 patients (25.0%). No patients achieved objective response. In the SHR7390 combination trial, 22 patients with CRC were enrolled. One DLT was reported in the 0.5 mg cohort and the MTD was not reached. Grade ≥3 TRAEs were observed in 8 patients (36.4%), with the most common being rash (n=4). One grade 5 TRAE (increased intracranial pressure) occurred. Five patients (22.7%) achieved partial response, including one of 3 patients with MSS/MSI-L and BRAF mutant tumors, one of 15 patients with MSS/MSI-L and BRAF wild type tumors, and all 3 patients with MSI-H tumors. CONCLUSIONS: SHR7390 0.5 mg plus camrelizumab showed a manageable safety profile. Preliminary clinical activity was reported regardless of MSI and BRAF status.

Aberrant Wnt/ß-catenin signaling and elevated expression of stem cell proteins are associated with osteosarcoma side population cells of high tumorigenicity.

According to the cancer stem cell theory, the presence of a small sub­population of cancer cells, termed cancer stem cells (CSCs), have a significant implication on cancer treatment and are responsible for tumor recurrence. Previous studies have reported that alterations in the Wnt/ß­catenin signaling are crucial in the maintenance of CSCs. In the present study, the characteristic features and activation of Wnt/ß­catenin signaling in CSCs from osteosarcoma, an aggressive human bone tumor, were investigated. In total, ~2.1% of the cancer stem­like side population (SP) cells were identified in the osteosarcoma samples. The results of subsequent western blot and reverse transcription­quantitative polymerase chain reaction analyses revealed that the protein levels of ß­catenin and cyclin D1 were markedly upregulated in the fluorescence­activated cell sorted osteosarcoma SP cells. In addition, the elevated expression levels of stem cell proteins, including CD133, nestin Oct­4, Sox­2 and Nanog were significantly higher in the SP cells, which contributed to self­renewal and enhanced the proliferation rate of the SP cells. Furthermore, the SP cells were found to be highly invasive and able to form tumors in vivo. Taken together, these data suggested that the identification of novel anticancer drugs, which suppress the Wnt/ß­catenin signaling and its downstream pathway may assist in eradicating osteosarcoma stem cells.