Cutaneous T-cell lymphoma (CTCL) is a heterogeneous group of neoplastic disorders characterized by clonally derived and skin-homing malignant T-cells that express high level of chemokine receptor CCR4, which is associated with their skin-homing capacity. CCR4 is also highly expressed on T-regulatory cells (Tregs) that can migrate to several different types of chemotactic ligand CCL17 and CCL22 secreting tumors to facilitate tumor cell evasion from immune surveillance. Thus, its high level expression on CTCL cells and Tregs makes CCR4 a potential ideal target for antibody-based immunotherapy for CTCL and other types of solid tumors. Here we performed humanization and affinity optimization of a murine anti-CCR4 monoclonal antibody (mAb), mAb1567, that recognizes both the N-terminal and extracellular domains of CCR4 with high affinity and inhibits chemotaxis of CCR4+ CTCL cells. In a mouse CTCL tumor model, mAb1567 exhibited a potent anti-tumor effect and in vitro mechanistic studies showed that both complement-dependent cytotoxicity (CDC) and neutrophil-mediated antibody-dependent cellular cytotoxicity (ADCC) likely mediated this effect. MAb1567 also exerts human NK cell-mediated ADCC activity in vitro. Moreover, mAb1567 also effectively inhibits chemotaxis of CD4+CD25high Tregs via CCL22 and abrogates Treg suppression activity in vitro. An affinity optimized variant of humanized mAb1567, mAb2-3, was selected for further preclinical development based on its higher binding affinity and more potent ADCC and CDC activities. Taken together, this high affinity humanized mAb2-3 with potent anti-tumor effect and a broad range of mechanisms of action may provide a novel immunotherapy for CTCL and other solid tumors.

TBK1 (TANK-binding kinase 1) is a noncanonical IkB protein kinase that phosphorylates and activates downstream targets such as IRF3 and c-Rel and, mediates NF-kB activation in cancer. Previous reports demonstrated synthetic lethality of TBK1 with mutant KRAS in non-small cell lung cancer (NSCLC); thus, TBK1 could be a novel target for treatment of KRAS-mutant NSCLC. Here, the effect of TBK1 on proliferation in a panel of cancer cells by both genetic and pharmacologic approaches was evaluated. In KRAS-mutant cancer cells, reduction of TBK1 activity by knockdown or treatment with TBK1 inhibitors did not correlate with reduced proliferation in a two-dimensional viability assay. Verification of target engagement via reduced phosphorylation of S386 of IRF3 (pIRF3 S386 ) was difficult to assess in NSCLC cells due to low protein expression. However, several cell lines were identified with high pIRF3 S386 levels after screening a large panel of cell lines, many of which also harbor KRAS mutations. Specifically, a large subset of KRAS-mutant pancreatic cancer cell lines was uncovered with high constitutive pIRF3 S386 levels, which correlated with high levels of phosphorylated S172 of TBK1 (pTBK1 S172 ).Finally, TBK1 inhibitors dose-dependently inhibited pIRF3 S386 in these cell lines, but this did not correlate with inhibition of cell growth. Taken together, these data demonstrate that the regulation of pathways important for cell proliferation in some NSCLC, pancreatic, and colorectal cell lines is not solely dependent on TBK1 activity.Implications: TBK1 has therapeutic potential under certain contexts and phosphorylation of its downstream target IRF3 is a biomarker of TBK1 activity.

One the main problems of cancer chemotherapy is the unwanted damage to normal cells caused by the high toxicities of anticancer drugs. Any system of controlled drug delivery that would reduce the total amount of drug required, and thus reduce the side effects, would potentially help to improve chemotherapy. In this respect, biodegradable gelatin microspheres were prepared by water/oil emulsion polymerization and by crosslinking with glutaraldehyde (GTA) as the drug-carrier system. Microspheres were loaded with colchicine, a model antimitotic drug, which was frequently used as an antimitotic agent in cancer research involving cell cultures. Microsphere sizes, swelling and degradation properties, drug-release kinetics, and cytotoxities were studied. Swelling characteristics of microspheres changed upon changing GTA concentration. A decrease in swelling values was recorded as GTA crosslink density was increased. In vitro drug release in PBS (0.01M, pH 7.4) showed rapid colchicine release up to approximately 83% (at t = 92 h) for microspheres with low GTA (0.05% v/v), whereas a slower release profile (only approximately 39%) was obtained for microspheres with high GTA (0.50% v/v) content, for the same period. Cytotoxicity tests with MCF-7, HeLa and H-82 cancer cell lines showed that free colchicine was very toxic, showing an approximately 100% lethal effect in both HeLa and H-82 cell lines and more than 50% decrease in viability in MCF-7 cells in 4 days. Indeed, entrapped colchicine indicated similar initial high toxic effect on cell viability in MCF-7 cell line and this effect became more dominant as colchicine continued to be released from microspheres in the same period. In conclusion, the control of the release rate of colchicine from gelatin microspheres was achieved under in vitro conditions by gelatin through the alteration of crosslinking conditions. Indeed, the results suggested the potential application of gelatin microspheres crosslinked with GTA as a sustained drug-delivery system for anticancer drugs for local chemotherapy administrations.