We have designed and developed novel and selective TLR7 agonists that exhibited potent receptor activity in a cell-based reporter assay. In vitro, these agonists significantly induced secretion of cytokines IL-6, IL-1 beta, IL-10, TNFa, IFNa, and IP-10 in human and mouse whole blood. Pharmacokinetic and pharmacodynamic studies in mice showed a significant secretion of IFN alpha and TNF alpha cytokines. When combined with aPD1 in a CT-26 tumor model, the lead compound showed strong synergistic antitumor activity with complete tumor regression in 8/10 mice dosed using the intravenous route. Structure-activity relationship studies enabled by structure-based designs of TLR7 agonists are disclosed.

Small molecule toll-like receptor (TLR) 7 agonists have gathered considerable interest as promising therapeutic agents for applications in cancer immunotherapy. Herein, we describe the development and optimization of a series of novel TLR7 agonists through systematic structure-activity relationship studies focusing on modification of the phenylpiperidine side chain. Additional refinement of ADME properties culminated in the discovery of compound 14, which displayed nanomolar reporter assay activity and favorable drug-like properties. Compound 14 demonstrated excellent in vivo pharmacokinetic/pharmacodynamic profiles and synergistic antitumor activity when administered in combination with aPD1 antibody, suggesting opportunities of employing 14 in immuno-oncology therapies with immune checkpoint blockade agents.

A comprehensive SAR study of a putative TLR 3/8/9 agonist was conducted. Despite the excitement surrounding the potential of the first small molecule TLR3 agonist with a compound that additionally displayed agonist activity for TLR8 and TLR9, compound 1 displayed disappointing activity in our hands, failing to match the potency (EC 50 ) reported and displaying only a low efficacy for the extent of stimulated NF-κB activation and release. The evaluation of >75 analogs of 1 , many of which constitute minor modifications in the structure, failed to identify any that displayed significant activity and none that exceeded the modest activity found for 1 .

A short, scalable total synthesis of meayamycin is described by an approach that entails a longest linear sequence of 12 steps (22 steps overall) from commercially available chiral pool materials (ethyl l-lactate, BocNH-Thr-OH, and d-ribose) and introduces the most straightforward preparation of the right-hand subunit detailed to date. The use of the approach in the divergent synthesis of a representative series of O-acyl analogues is exemplified.

The synthesis of a 1,2,9,9a-tetrahydrocyclopropa[c]benz[e]indol-4-one (CBI)-adenine adduct via regioselective N-3 alkylation of adenine with a 1-(iodomethyl)-2,3-dihydro-1H-benzo[e]indol-5-ol (I-seco-CBI)-containing precursor is described. Spectroscopic analyses of the unlabeled and adenine-C8 carbon-13 labeled adducts utilizing ROESY NMR techniques allowed structural assignment of the alkylation product as the adenine N-3 substituted regioisomer. A stable-isotopically labeled version of the N-3 adduct incorporating six carbon-13 labels was also prepared by this method for use as an LC-MS internal standard. The cyclized CBI-containing compound was also found to alkylate adenine at elevated temperatures to produce the N-3 adduct albeit at a significantly slower rate than that observed for the I-seco-CBI precursor. Adenine alkylation with an I-seco-CBI precursor offers scalable and facile access to a CBI-adenine adduct facilitating its use as an efficacy marker for the development of duocarmycin-based ADCs.