Abstract 2491: Engineering and preclinical activity of MM-201, a best-in-class TRAIL receptor agonist
Authors: Sawyer Andrew J. , Ghassemifar Sara , Wong Christina , Richards Jennifer , Grabow Stephanie , Suchy James , Koshkaryev Alexander , Razlog Maja , Tam Eric , Drummond Daryl C. 
Published: August 2019

Abstract
Early attempts at using TNF superfamily members for anticancer therapies, TNF and FAS, led to serious systemic toxicities. However, the discovery of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) introduced an agonist capable of killing tumor cells via apoptosis without the side effects observed with TNF and FAS agonists. First generation TRAIL agonists included a recombinant version of human TRAIL (dulanermin), as well as multiple DR4 and DR5 agonist antibodies. Despite some isolated responders, the initial clinical results were poor. The first-generation TRAIL agonists were limited by poor pharmacokinetics (the half-life for dulanermin was between 30 and 60 minutes) or by poor agonist activity and the need for Fc-mediated cross linking. Here we present the development and evaluation of two second generation TRAIL agonists, MM-201a and MM-201b. Both versions are composed of an IgG1 Fc fused to a single chain TRAIL trimer (Fc-scTRAIL). Mutations within the TRAIL domains, selected from a random mutagenesis library, were introduced to improve stability, expression, and DR5 binding. MM-201a has 5 mutations in each monomeric unit (R130G/N228S/I247V/Y213W/S215D) and MM-201b has 3 mutations in each monomer (R130G/N228S/I247V). In a panel of 27 colorectal carcinoma and sarcoma cell lines, both versions of MM-201 were observed to be significantly more active than all comparators, including the TRAIL cytokine and both DR4 and DR5 antibodies. MM-201a had a level of activity similar to ABBV-621, a single chain TRAIL fused to the N-terminus of an IgG1 Fc that is currently the subject of a Phase 1 trial. However, MM-201b was significantly more active than both MM-201a and ABBV-621, with up to 11-fold lower IC50 across a panel of 12 CRC cell lines. MM-201b treatment reduced cell viability to less than 20% in 10 out 12 colorectal cancer cell lines and in 8 of these cell lines, this was achieved at concentrations less than 1 nM. MM-201 also induced complete cell death at 1 nM or less in 3 of 8 synovial sarcoma and chondrosarcoma cell lines tested. For example, MM-201b reduced the viability of the SW-982 synovial sarcoma cell line to 17% at a dose of 1.5 pM, which is nearly twice the reduction in viability from the same dose of ABBV-621. We next evaluated both versions of MM-201 in multiple colorectal cancer and sarcoma patient-derived xenograft (PDX) models. In the Ewing’s sarcoma PDX model TM01617, MM-201b treatment resulted in 90% tumor growth inhibition. In the same model, treatment with 10 mg/kg docetaxel resulted in 73% growth inhibition; however, in combination with MM-201a, the same dose resulted in a 100% complete response rate. Similar results were observed in the SK-UT1 uterine sarcoma xenograft. Based on this evidence, we believe that MM-201b is best in class and, when combined with an appropriate patient selection strategy, has significant potential for the treatment of sarcomas and colorectal cancer in patients.
Citation Format: Andrew J. Sawyer, Sara Ghassemifar, Christina Wong, Jennifer Richards, Stephanie Grabow, James Suchy, Alexander Koshkaryev, Maja Razlog, Eric Tam, Daryl C. Drummond. Engineering and preclinical activity of MM-201, a best-in-class TRAIL receptor agonist [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2491.