Antigen-independent tumor targeting by CBX-12 (alphalex™-exatecan) induces long-term antitumor immunity.

Aims: To determine whether antigen-independent targeting of the TOP1 inhibitor exatecan to tumor with a pH-sensitive peptide (CBX-12) produces superior synergy with immunotherapy compared with unconjugated exatecan. Materials & methods: In vitro and ex vivo functional assays were performed via FACS and ELISA assays. In vivo efficacy was evaluated in the syngeneic CT26 model. Results: CBX-12 combined with anti-PD-1 or anti-CTLA4 results in delayed tumor growth and complete response, with cured animals displaying long-term antitumor immunity. CBX-12 stimulates expression of MHC 1 and PD-L1 and is an inducer of immunogenic cell death, producing long-term immune recognition of tumor cells and resultant antitumor immunity. Conclusion: The authors' data provide the rationale for exploring immunotherapy combinations with CBX-12 in clinical trials.

Although combinations of chemotherapy and immunotherapy have shown great promise for cancer treatment, they have also demonstrated significant safety concerns that require dose reductions. Targeting chemotherapy to the tumor can avoid these safety issues, thereby enhancing efficacy of combination therapies. CBX-12 is a novel peptide-drug agent targeting the TOP1-inhibiting drug exatecan to tumor via pH-sensitive peptide. Unlike tumor targeting via antibody, CBX-12 universally targets all solid tumors. CBX-12 avoids the immune cell toxicity of nontumor-targeted exatecan and safely synergizes with immunotherapies. CBX-12 treatment causes tumor cells to express and secrete molecules that result in activation of immune components to recognize and eliminate tumor cells. These data support the upcoming clinical trials of CBX-12 in combination with immunotherapy.

Correction to 'Tumor-selective, antigen-independent delivery of a pH sensitive peptide-topoisomerase inhibitor conjugate suppresses tumor growth without systemic toxicity'.

[This corrects the article DOI: 10.1093/narcan/zcab021.].

Tumor-selective, antigen-independent delivery of a pH sensitive peptide-topoisomerase inhibitor conjugate suppresses tumor growth without systemic toxicity.

Topoisomerase inhibitors are potent DNA damaging agents which are widely used in oncology, and they demonstrate robust synergistic tumor cell killing in combination with DNA repair inhibitors, including poly(ADP)-ribose polymerase (PARP) inhibitors. However, their use has been severely limited by the inability to achieve a favorable therapeutic index due to severe systemic toxicities. Antibody-drug conjugates address this issue via antigen-dependent targeting and delivery of their payloads, but this approach requires specific antigens and yet still suffers from off-target toxicities. There is a high unmet need for a more universal tumor targeting technology to broaden the application of cytotoxic payloads. Acidification of the extracellular milieu arises from metabolic adaptions associated with the Warburg effect in cancer. Here we report the development of a pH-sensitive peptide-drug conjugate to deliver the topoisomerase inhibitor, exatecan, selectively to tumors in an antigen-independent manner. Using this approach, we demonstrate potent in vivo cytotoxicity, complete suppression of tumor growth across multiple human tumor models, and synergistic interactions with a PARP inhibitor. These data highlight the identification of a peptide-topoisomerase inhibitor conjugate for cancer therapy that provides a high therapeutic index, and is applicable to all types of human solid tumors in an antigen-independent manner.

The CD40 agonist antibody CP-870,893 enhances dendritic cell and B-cell activity and promotes anti-tumor efficacy in SCID-hu mice.

CD40 is a member of the TNF family of receptors that has been shown to play a crucial role in enhancing dendritic cell activity and fostering anti-tumor immune responses. In this study, we demonstrate the in vitro properties and in vivo efficacious activity of the CD40 agonist antibody, CP-870,893. CP-870,893 is a fully human, IgG2 antibody that selectively interacts with CD40 at a site distinct from its ligand-binding region with a KD of 0.4 nM. It enhances the expression of MHC class II, CD54, CD86, and CD23 on human B cells in vitro. CP-870,893 also enhances dendritic cell activity as evidenced by cytokine secretion (IL-12, IL-23, IL-8), the upregulation of CD86 and CD83, and the ability to prime T cells to secrete IFNγ. In SCID-beige mice, a single parenteral injection of CP-870,893 was therapeutically effective against several CD40(pos) human tumors (B-cell lymphoma, breast, colon, and prostate) indicating direct effects on tumor cell survival and/or growth. When mice were co-implanted with human T cells and dendritic cells, the activity of CP-870,893 against CD40(pos) tumors increased, and efficacy was also observed against CD40(neg) and CD40(low) tumors demonstrating the ability of CP-870,893 to enhance anti-tumor immune function in vivo. These studies suggest that CP-870,893 has the potential to be efficacious against a wide range of tumor types through both direct and immune-mediated effects.

Essential role of CCR6 in directing activated T cells to the skin during contact hypersensitivity.

CCR6 is expressed in a number of dermatological inflammatory diseases. Here, we report that mice sensitized with the hapten oxazolone had increased numbers of CCR6+ T cells in the draining lymph nodes. Using CCR6-/- mice, we assessed the role of CCR6 on the development of contact hypersensitivity. After hapten sensitization and re-challenge, ear swelling in CCR6-/- animals was reduced 80% as compared with wild-type (WT) control mice. This decreased level of inflammation was not related to an inhibition in T-cell activation, because CCR6-/- lymph node cells from sensitized mice produced threefold higher levels of IFN-gamma in culture than cells from sensitized WT mice and, when these cells were directly injected into the site of hapten challenge, induced a robust inflammatory response. However, intravenous injection of CCR6-/- lymph node cells from sensitized mice were unable to prime naive mice to re-challenge whereas cells from primed WT mice were able to sensitize animals. These results suggest that CCR6 plays an important role in directing the trafficking of activated T cells into the skin and suggests that a CCR6 antagonist could be useful to treat skin-mediated inflammatory reactions.

Piperazinyl CCR1 antagonists--optimization of human liver microsome stability.

The synthesis, biological activity, and pharmacokinetic profile of CCR1 antagonists are described.

Potent small molecule CCR1 antagonists.

The present manuscript details structure-activity relationship studies of lead structure 1, which led to the discovery of CCR1 antagonists >100-fold more potent than 1.

Novel CCR1 antagonists with improved metabolic stability.

The synthesis, biological activity, and pharmacokinetic profile of novel CCR1 antagonists are described.

CP-481,715, a potent and selective CCR1 antagonist with potential therapeutic implications for inflammatory diseases.

The chemokines CCL3 and CCL5, as well as their shared receptor CCR1, are believed to play a role in the pathogenesis of several inflammatory diseases including rheumatoid arthritis, multiple sclerosis, and transplant rejection. In this study we describe the pharmacological properties of a novel small molecular weight CCR1 antagonist, CP-481,715 (quinoxaline-2-carboxylic acid [4(R)-carbamoyl-1(S)-(3-fluorobenzyl)-2(S),7-dihydroxy-7-methyloctyl]amide). Radiolabeled binding studies indicate that CP-481,715 binds to human CCR1 with a Kd of 9.2 nm and displaces 125I-labeled CCL3 from CCR1-transfected cells with an IC50 of 74 nm. CP-481,715 lacks intrinsic agonist activity but fully blocks the ability of CCL3 and CCL5 to stimulate receptor signaling (guanosine 5'-O-(thiotriphosphate) incorporation; IC50 = 210 nm), calcium mobilization (IC50 = 71 nm), monocyte chemotaxis (IC50 = 55 nm), and matrix metalloproteinase 9 release (IC50 = 54 nm). CP-481,715 retains activity in human whole blood, inhibiting CCL3-induced CD11b up-regulation and actin polymerization (IC50 = 165 and 57 nm, respectively) on monocytes. Furthermore, it behaves as a competitive and reversible antagonist. CP-481,715 is >100-fold selective for CCR1 as compared with a panel of G-protein-coupled receptors including related chemokine receptors. Evidence for its potential use in human disease is suggested by its ability to inhibit 90% of the monocyte chemotactic activity present in 11/15 rheumatoid arthritis synovial fluid samples. These data illustrate that CP-481,715 is a potent and selective antagonist for CCR1 with therapeutic potential for rheumatoid arthritis and other inflammatory diseases.