ABSTRACT
Immunocytokines hold great potential as anticancer agents, as they use a specific antitumor antibody to deliver an immune-activating cytokine directly to the immunosuppressive tumor microenvironment (TME). We have developed a novel immunocytokine (KD033) composed of a fully human, high-affinity antiprogrammed death-ligand 1 (PD-L1) linked to the sushi-domain of the human IL-15/IL-15 receptor alpha (IL-15/IL-15Rα) complex. A murine PD-L1 cross-reactive KD033 surrogate (srKD033) and a nontargeting antibody (ntKD033) were also developed to investigate mechanism of action in murine tumor models. Efficacy analyses showed a robust antitumor effect of single-dose srKD033 in several diverse syngeneic murine tumor models. In a CT26 murine colon tumor model, single-dose srKD033 produced durable antitumor immunity as evidenced by resistance to subsequent tumor rechallenges. Mice responding to srKD033 treatment showed increased retention of PD-L1/IL-15 in the TME which likely facilitated prolonged IL-15-induced expansion of cytotoxic cells. Importantly, target-based PD-L1/IL-15 delivery via srKD033 was well-tolerated and induced significant antitumor activity in murine carcinoma models that are non- or minimally responsive to IL-15 or anti-PD-L1/PD-1 monotherapy.
Subject(s)
B7-H1 Antigen/antagonists & inhibitors , Drug Synergism , Immunotherapy/methods , Interleukin-15/metabolism , Oncogene Proteins, Fusion/metabolism , Animals , Cell Line, Tumor , Disease Models, Animal , Humans , MiceABSTRACT
A generic activation mode for asymmetric LUMO-lowering catalysis has been developed using the long-established principles of oxy-allyl cation chemistry. Here, the enantioselective conversion of racemic α-tosyloxy ketones to optically enriched α-indolic carbonyls has been accomplished using a new amino alcohol catalyst in the presence of electron-rich indole nucleophiles. Kinetic studies reveal that the rate-determining step in this S(N)1 pathway is the catalyst-mediated α-tosyloxy ketone deprotonation step to form an enantiodiscriminant oxy-allyl cation prior to the stereodefining nucleophilic addition event.
