A Potent and Selective Dual Inhibitor of AXL and MERTK Possesses Both Immunomodulatory and Tumor-Targeted Activity.

TYRO3, AXL, and MERTK constitute the TAM family of receptor tyrosine kinases, which play important roles in tumor growth, survival, cell adhesion, as well as innate immunity, phagocytosis, and immune-suppressive activity. Therefore, targeting both AXL and MERTK kinases may directly impact tumor growth and relieve immunosuppression. We describe here the discovery of INCB081776, a potent and selective dual inhibitor of AXL and MERTK that is currently in phase 1 clinical trials.

Characterization of human cancer xenografts in humanized mice.

Background: Preclinical evaluation of drugs targeting the human immune system has posed challenges for oncology researchers. Since the commercial introduction of humanized mice, antitumor efficacy and pharmacodynamic studies can now be performed with human cancer cells within mice bearing components of a human immune system. However, development and characterization of these models is necessary to understand which model may be best suited for different agents.

Evaluation of Pyrrolobenzodiazepine-Loaded Nanoparticles: A Targeted Drug Delivery Approach.

We describe the development and evaluation of pyrrolobenzodiazepines (PBDs) in poly(dl-lactide-co-glycolide) and lipid nanoparticle drug delivery systems. We have established that the partition coefficient (LogP) of PBD is a key influencer of the encapsulation efficiency in nanoparticle systems, with higher LogP values associated with higher encapsulation efficiencies toward increased drug payload delivery and better antitumor efficacy. Cytotoxicity assays demonstrated that compounds with higher LogP values demonstrated higher 50% inhibitory concentration values than the free drug.

Targeting ADAM17 inhibits human colorectal adenocarcinoma progression and tumor-initiating cell frequency.

ADAM17 (a disintegrin and metalloproteinase 17)/TACE (TNFα converting enzyme) has emerged as a potential therapeutic target in colorectal cancer (CRC) and other cancers, due in part to its role in regulating various tumor cell surface proteins and growth factors and cytokines in the tumor microenvironment. The emergence of MEDI3622, a highly potent and specific antibody-based ADAM17 inhibitor, has allowed testing of the concept that targeting ADAM17 may be an important new therapeutic approach for CRC patients. We demonstrate that MEDI3622 is highly efficacious on tumor growth in multiple human CRC PDX models, resulting in improved survival of animals bearing tumor xenografts.

Antibody-Drug Conjugates Bearing Pyrrolobenzodiazepine or Tubulysin Payloads Are Immunomodulatory and Synergize with Multiple Immunotherapies.

Immunogenic cell death (ICD) is the process by which certain cytotoxic drugs induce apoptosis of tumor cells in a manner that stimulates the immune system. In this study, we investigated whether antibody-drug conjugates (ADCS) conjugated with pyrrolobenzodiazepine dimer (PBD) or tubulysin payloads induce ICD, modulate the immune microenvironment, and could combine with immuno-oncology drugs to enhance antitumor activity. We show that these payloads on their own induced an immune response that prevented the growth of tumors following subsequent tumor cell challenge.

Targeting CD73 in the tumor microenvironment with MEDI9447.

MEDI9447 is a human monoclonal antibody that is specific for the ectoenzyme CD73 and currently undergoing Phase I clinical trials. Here we show that MEDI9447 is a potent inhibitor of CD73 ectonucleotidase activity, with wide ranging immune regulatory consequences. MEDI9447 results in relief from adenosine monophosphate (AMP)-mediated lymphocyte suppression in vitro and inhibition of mouse syngeneic tumor growth in vivo.

Lipid- and polyion complex-based micelles as agonist platforms for TNFR superfamily receptors.

Receptor clustering is important for signaling among the therapeutically relevant TNFR superfamily of receptors. In nature, this clustering is driven by trimeric ligands often presented in large numbers as cell surface proteins. Molecules capable of driving similar levels of clustering could make good agonists and hold therapeutic value.

Doxil synergizes with cancer immunotherapies to enhance antitumor responses in syngeneic mouse models.

Based on the previously described roles of doxorubicin in immunogenic cell death, both doxorubicin and liposomal doxorubicin (Doxil) were evaluated for their ability to boost the antitumor response of different cancer immunotherapies including checkpoint blockers (anti-PD-L1, PD-1, and CTLA-4 mAbs) and TNF receptor agonists (OX40 and GITR ligand fusion proteins) in syngeneic mouse models. In a preventative CT26 mouse tumor model, both doxorubicin and Doxil synergized with anti-PD-1 and CTLA-4 mAbs. Doxil was active when CT26 tumors were grown in immunocompetent mice but not immunocompromised mice, demonstrating that Doxil activity is increased in the presence of a functional immune system.

A Monoclonal Antibody to ADAM17 Inhibits Tumor Growth by Inhibiting EGFR and Non-EGFR-Mediated Pathways.

ADAM17 is the primary sheddase for HER pathway ligands. We report the discovery of a potent and specific ADAM17 inhibitory antibody, MEDI3622, which induces tumor regression or stasis in many EGFR-dependent tumor models. The inhibitory activity of MEDI3622 correlated with EGFR activity both in a series of tumor models across several indications as well in as a focused set of head and neck patient-derived xenograft models.

A versatile polymer micelle drug delivery system for encapsulation and in vivo stabilization of hydrophobic anticancer drugs.

Chemotherapeutic drugs are widely used for the treatment of cancer; however, use of these drugs is often associated with patient toxicity and poor tumor delivery. Micellar drug carriers offer a promising approach for formulating and achieving improved delivery of hydrophobic chemotherapeutic drugs; however, conventional micelles do not have long-term stability in complex biological environments such as plasma. To address this problem, a novel triblock copolymer has been developed to encapsulate several different hydrophobic drugs into stable polymer micelles.

IT-141, a Polymer Micelle Encapsulating SN-38, Induces Tumor Regression in Multiple Colorectal Cancer Models.

Polymer micelles are promising drug delivery vehicles for the delivery of anticancer agents to tumors. Often, anticancer drugs display potent cytotoxic effects towards cancer cells but are too hydrophobic to be administered in the clinic as a free drug. To address this problem, a polymer micelle was designed using a triblock copolymer (ITP-101) that enables hydrophobic drugs to be encapsulated.

Ectopic expression of histone H2AX mutants reveals a role for its post-translational modifications.

Recent evidence from a wide variety of biological systems has indicated important regulatory roles for post-translation histone modifications in cellular processes such as regulation of gene expression, DNA damage response and recombination. Phosphorylation of histone H2AX at serine 139 is a critical event in the response to DNA damage, but the functional implications of this modification are not yet clear. To investigate the role of H2AX phosphorylation we ectopically expressed epitope-tagged H2AX or mutants at the phosphorylation site.

DNA damage response: determining the fate of phosphorylated histone H2AX.

Phosphorylation of histone H2AX at Serine 139 is one of the earliest events after DNA damage and is required for the retention of factors involved in repair at the site of the break. Intriguingly, H2AX phosphorylation spreads from the vicinity of the break to both directions spanning large chromosomal regions. Phosphorylated H2AX (also known as gamma-H2AX) then progressively disappears with kinetics that correlates with the completion of DNA repair.

Truncated E-cadherin potentiates cell death in prostate epithelial cells.

Background: E-cadherin, a fundamental component of the adherens junction, is known to mediate aggregation-dependent cell survival. We have previously identified a novel, calpain-dependent proteolytic cleavage of E-cadherin that resulted in the generation of a stable 100-kDa E-cadherin fragment (E-cad(100)) in prostate epithelial cells in response to cell death stimuli. We postulated that the E-cad(100) fragment may play a role in abrogating survival of LNCaP cells following induction of apoptosis.

Cleavage of beta-catenin by calpain in prostate and mammary tumor cells.

Mutations in the NH(2)-terminal regulatory domain of the beta-catenin gene lead to aberrant stabilization and accumulation of the protein and increased TCF/LEF-dependent transcription. Although these mutations are common in some cancers, they are infrequent in prostate and breast cancer. We have found that metastatic prostate cancer specimens, obtained through a rapid autopsy tissue procurement program, expressed a novel M(r) 75,000 proteolytic fragment of beta-catenin (beta-cat(75)).

The role of calpain in the proteolytic cleavage of E-cadherin in prostate and mammary epithelial cells.

The E-cadherin protein mediates Ca(2+)-dependent interepithelial adhesion. Association of E-cadherin with the catenin family of proteins is critical for the maintenance of a functional adhesive complex. We have identified a novel truncated E-cadherin species of 100-kDa (E-cad(100)) in prostate and mammary epithelial cells.