MTL-CEBPA, a Small Activating RNA Therapeutic Upregulating C/EBP-α, in Patients with Advanced Liver Cancer: A First-in-Human, Multicenter, Open-Label, Phase I Trial.

PURPOSE: Transcription factor C/EBP-α (CCAAT/enhancer-binding protein alpha) acts as a master regulator of hepatic and myeloid functions and multiple oncogenic processes. MTL-CEBPA is a first-in-class small activating RNA oligonucleotide drug that upregulates C/EBP-α. PATIENTS AND METHODS: We conducted a phase I, open-label, dose-escalation trial of MTL-CEBPA in adults with advanced hepatocellular carcinoma (HCC) with cirrhosis, or resulting from nonalcoholic steatohepatitis or with liver metastases. Patients received intravenous MTL-CEBPA once a week for 3 weeks followed by a rest period of 1 week per treatment cycle in the dose-escalation phase (3+3 design). RESULTS: Thirty-eight participants have been treated across six dose levels (28-160 mg/m2) and three dosing schedules. Thirty-four patients were evaluable for safety endpoints at 28 days. MTL-CEBPA treatment-related adverse events were not associated with dose, and no maximum dose was reached across the three schedules evaluated. Grade 3 treatment-related adverse events occurred in nine (24%) patients. In 24 patients with HCC evaluable for efficacy, an objective tumor response was achieved in one patient [4%; partial response (PR) for over 2 years] and stable disease (SD) in 12 (50%). After discontinuation of MTL-CEBPA, seven patients were treated with tyrosine kinase inhibitors (TKIs); three patients had a complete response with one further PR and two with SD. CONCLUSIONS: MTL-CEBPA is the first saRNA in clinical trials and demonstrates an acceptable safety profile and potential synergistic efficacy with TKIs in HCC. These encouraging phase I data validate targeting of C/EBP-α and have prompted MTL-CEBPA + sorafenib combination studies in HCC

Novel therapeutic approaches with small activating RNA

Oligonucleotide therapeutics is a major platform for drug discovery with great potential for diseases where endogenous gene expression is downregulated. In 2016, MTL-CEBPA was the first RNA activating oligonucleotide drug targeting CEBPA to enter clinical development for patients with advanced hepatocellular carcinoma (HCC). The aim of this PhD project is to develop new therapeutic small activating RNAs (saRNAs) for genes which are suppressed in the pathology of inflammation, Non-alcoholic Fatty Liver Disease (NAFLD) and Non-Alcoholic Steato-Hepatitis (NASH). saRNAs for three different targets namely Sirtuin 1 (SIRT1), Hepatocyte Nuclear Factor 1-Alpha (HNF1A) and Fibroblast Growth Factor 21 (FGF21) are investigated. SIRT1 is a protein with anti-apoptotic, anti-ageing and anti-inflammatory properties. SIRT1-PR57 saRNA is identified as the most promising candidate to upregulate SIRT1 mRNA and protein levels. The therapeutic potential of SIRT1-PR57 saRNA is experimentally explored in cell models of lipid metabolic disorders as well as inflammatory diseases and is the central theme of this thesis. Other targets touched upon but not fully explored include HNF1A and FGF21. HNF1A is a liver enriched transcription factor involved in Maturity Onset Diabetes of the Young (MODY), pancreatic ductal adenocarcinoma (PDAC) and HCC. HNF1A-PR1 saRNA is shown to successfully upregulate the mRNA levels of the HNF1A(A) isoform, while protein levels still require further validation. Investigation in relation to FGF21, a metabolic hormone regulating lipid metabolism, demonstrated that the FGF21 transcript is not present in hepatocytes. FGF21 saRNA candidates might yield more promising results in other liver cell lines with the potential to reverse the pathology of NAFLD and NASH. Finally, SIRT1 saRNA could have therapeutic effect as an anti-inflammatory regulatory component within macrophages.Open Acces

Upregulation of C/EBPα Inhibits Suppressive Activity of Myeloid Cells and Potentiates Antitumor Response in Mice and Patients with Cancer.

PURPOSE: To evaluate the mechanisms of how therapeutic upregulation of the transcription factor, CCAAT/enhancer-binding protein alpha (C/EBPα), prevents tumor progression in patients with advanced hepatocellular carcinoma (HCC) and in different mouse tumor models. EXPERIMENTAL DESIGN: We conducted a phase I trial in 36 patients with HCC (NCT02716012) who received sorafenib as part of their standard care, and were given therapeutic C/EBPα small activating RNA (saRNA; MTL-CEBPA) as either neoadjuvant or adjuvant treatment. In the preclinical setting, the effects of MTL-CEBPA were assessed in several mouse models, including BNL-1ME liver cancer, Lewis lung carcinoma (LLC), and colon adenocarcinoma (MC38). RESULTS: MTL-CEBPA treatment caused radiologic regression of tumors in 26.7% of HCC patients with an underlying viral etiology with 3 complete responders. MTL-CEBPA treatment in those patients caused a marked decrease in peripheral blood monocytic myeloid-derived suppressor cell (M-MDSC) numbers and an overall reduction in the numbers of protumoral M2 tumor-associated macrophages (TAM). Gene and protein analysis of patient leukocytes following treatment showed CEBPA activation affected regulation of factors involved in immune-suppressive activity. To corroborate this observation, treatment of all the mouse tumor models with MTL-CEBPA led to a reversal in the suppressive activity of M-MDSCs and TAMs, but not polymorphonuclear MDSCs (PMN-MDSC). The antitumor effects of MTL-CEBPA in these tumor models showed dependency on T cells. This was accentuated when MTL-CEBPA was combined with checkpoint inhibitors or with PMN-MDSC-targeted immunotherapy. CONCLUSIONS: This report demonstrates that therapeutic upregulation of the transcription factor C/EBPα causes inactivation of immune-suppressive myeloid cells with potent antitumor responses across different tumor models and in cancer patients. MTL-CEBPA is currently being investigated in combination with pembrolizumab in a phase I/Ib multicenter clinical study (NCT04105335)

Upregulation of C/EBP alpha Inhibits Suppressive Activity of Myeloid Cells and Potentiates Antitumor Response in Mice and Patients with Cancer

To evaluate the mechanisms of how therapeutic upregulation of the transcription factor, C/EBP\u3b1, prevents tumor progression in patients with advanced hepatocellular carcinoma (HCC) and in different mouse tumor models