Current Opinion in Investigational Drugs

Disease Control Rate (DCR) and Clinical Benefit Rate (CBR) are defined as the percentage of patients with advanced or metastatic cancer who have achieved complete response, partial response and stable disease to a therapeutic intervention in clinical trials of anticancer agents. DCR and CBR are commonly reported in many clinical trials in abstracts, papers, meeting presentations and media releases. The frequent use of these measures of drug activity presents the question of whether DCR and CBR are useful additional endpoints in early clinical trials, and if they can reasonably predict the success of an agent in subsequent, adequately powered, randomized trials...

Crizotinib (PF-02341066), under development by Pfizer, is an orally bioavailable, ATP-competitive, small-molecule inhibitor of the receptor tyrosine kinases (RTKs) c-Met (also known as hepatocyte growth factor receptor) and anaplastic lymphoma kinase (ALK), for the potential treatment of cancers dependent on these oncogenic kinases for growth and survival. Since the first published characterizations of crizotinib only a few years ago, the drug has been extensively validated as a highly specific inhibitor of c-Met and ALK among > 120 different RTKs surveyed...

STA-9090 is a second-generation Hsp90 inhibitor in clinical development by Synta Pharmaceuticals for the intravenous treatment of hematological and solid malignancies. It is a resorcinol-containing triazole compound, with a novel chemical structure that is unrelated to the geldanamycin class of Hsp90 inhibitors. STA-9090 binds to the ATP-binding domain at the N-terminus of Hsp90 and acts as a potent Hsp90 inhibitor by inducing degradation of multiple oncogenic Hsp90 client proteins including HER2/neu, mutated EGFR, Akt, c-Kit, IGF-1R, PDGFRα, Jak1, Jak2, STAT3, STAT5, HIF-1α, CDC2, c-Met, and Wilms' tumor 1...

Bafetinib (NS-187, INNO-406) is a second-generation tyrosine kinase inhibitor in development by CytRx under license from Nippon Shinyaku for treating Bcr-Abl+ leukemia's, including chronic myelogenous leukemia (CML) and Philadelphia+ acute lymphoblastic leukemia. It is a rationally developed tyrosine kinase inhibitor based on the chemical structure of imatinib, with modifications added to improve binding and potency against Bcr-Abl kinase. Besides Abl, bafetinib targets the Src family kinase Lyn, which has been associated with resistance to imatinib in CML...

AT-9283 has been identified and developed by Astex Therapeutics via structure-based optimization of a ligand-efficient pyrazole-benzimidazole fragment. AT-9283 inhibits several important kinases, including the Aurora kinase A, Aurora kinase B, Janus kinase (Jak)2, Jak3 and Abl kinase. Studies using multiple solid tumor and leukemia cell lines have demonstrated the ability of AT-9283 to inhibit growth and survival of tumor cells, and the direct inhibition of these kinases has been demonstrated in cell-based systems...

Necitumumab (IMC-11F8), under development by ImClone Systems in collaboration with Bristol-Myers Squibb, is a fully human IgG1 mAb targeting the epidermal growth factor receptor (EGFR), for the potential intravenous treatment of cancer, in particular NSCLC. In vitro studies demonstrate that necitumumab inhibits downstream targets in the EGFR pathway (eg, MAPK), which are important for cellular proliferation, differentiation, invasion and metastasis. Furthermore, because necitumumab is an IgG1 construct, it has the potential to induce antibody-dependent cell-mediated cytotoxicity against tumor cells...

EC-145, under development by Endocyte, is a conjugate composed of desacetylvinblastine monohydrazide linked through a peptide spacer to the targeting moiety folic acid, for the potential intravenous treatment of folate receptor-overexpressing tumors, in particular ovarian and lung cancers. In vitro studies demonstrated that EC-145 selectively binds to cells that overexpress the folate receptor, causing dose-dependent cytotoxicity. Furthermore, coincubation of the KB human nasopharyngeal carcinoma cell line with EC-145 and doxorubicin resulted in synergistic antitumor activity...

More than 50 years after the introduction of the dihydrofolate reductase inhibitor, methotrexate, new antifolates have emerged and have been incorporated into the chemotherapeutic armamentarium. These include pralatrexate, with the same target as methotrexate, but with enhanced properties, and pemetrexed, with different enzyme targets and properties. Current synthetic efforts are focused on developing antifolates that are selectively delivered to cancer cells, but not to normal proliferating cells, exploiting the different properties of folate transporters...

Considerable research in the field of immunotherapy for melanoma has demonstrated that this tumor type can be responsive to therapeutic immune activation strategies. In early clinical trials, vaccine strategies using dendritic cells (DCs) and adenovirus (Ad) vectors (AdVs) were safe and immunogenic, and induced clinical responses in a minority of patients. Research from the past several years has yielded an improved mechanistic understanding of DC biology, AdV effects on DCs and the crosstalk that occurs between antigen-loaded DCs and specific lymphocyte subsets...

Recent evidence has demonstrated that aberrant reactivation of the Hedgehog signaling pathway contributes to tumor initiation and progression in various human malignancies, including pancreatic cancer; therefore, the Hedgehog pathway has emerged as a promising novel therapeutic target. Initial translational studies conducted using cyclopamine, a small-molecule inhibitor of the Smoothened (SMO) component of the Hedgehog pathway, demonstrated that pharmacological blockade of aberrant Hedgehog signaling has the potential to inhibit tumor initiation, progression and metastatic spread...

Since the development of the first vaccines, modern medicine has been consistently aiming to improve the efficacy of immune responses. Traditionally, adjuvants have been used as non-specific immune modulators to enhance recognition and activation against a desired antigen. By providing 'danger' signals to the immune system, adjuvants activate innate immunity, which enhances the development of protective and therapeutic adaptive immune responses. The newest class of immune modulators bypasses the innate response and targets cells of the adaptive response directly...

Infection with HBV and HCV are considered the most important etiological factors for hepatocellular carcinoma (HCC). Current treatment options are insufficient, creating an urgent need for new therapeutic strategies that inhibit disease progression and improve survival in patients with HCC. A promising strategy for the treatment of HCC is gene therapy (GT), which is characterized by the transduction of tumor cells with genes displaying antitumor properties, such as pro-apoptotic, suicide, anti-angiogenic and immunomodulatory genes, as well as siRNAs...

Mammalian target of rapamycin (mTOR) complex 1 (mTORC1) is a multicomponent, nutrient-sensitive protein that is implicated in a wide range of major human diseases. mTORC1 responds to both growth factors and changes in local amino acid levels. Until recently, the intracellular amino acid-sensing mechanism that regulates mTORC1 had remained unexplored. However, studies in human cells in culture have demonstrated that in response to amino acid stimulation, mTOR (a conserved member of the PI3K superfamily) is shuttled to late endosomal and lysosomal compartments, where it binds the Ragulator-Rag complex and is assembled into active mTORC1...

Tumor antigen-specific T-cell function is regulated by both positive and negative costimulatory signals, which are received in the secondary lymphoid organs and within the tumor microenvironment. Tumor-induced T-cell dysfunction results from a lack of positive costimulatory signals, combined with a predominance of negative immunoregulatory mechanisms. The engagement of the protein programmed death 1 (PD1), expressed on activated T-cells, by programmed death ligand 1 (PD-L1)/B7H1 within tumor cells or other host-derived cells results in the downregulation of T-cell function, and represents an important negative regulatory pathway...

There is considerable evidence suggesting that a variety of malignancies utilize the TGFβ cytokine to evade immune surveillance mechanisms to facilitate tumor growth and metastatic progression. The recently developed large- and small-molecule TGFβ inhibitors have demonstrated antitumor efficacy in several preclinical tumor models. Further investigation has revealed these agents to be critically dependent upon the host's immune system, suggesting that the inhibition of TGFβ may overcome the immunosuppressive tumor microenvironment and, ultimately, augment the antitumor immune response...

Brain and spinal cord injuries result in cognitive and/or sensorimotor impairments that can significantly diminish the quality of life for the patient and their carers, and result in healthcare system costs totaling in the billions. The current gold-standard of acute care for spinal cord injury is to administer high doses of glucocorticoids within 8 h of injury; administration after 8 h may be without effect or detrimental to the outcome of the patient. Therefore, improved pharmacological approaches for limiting the extent of tissue damage and neurological dysfunction in the acute injury setting are urgently needed...

Teriflunomide, being developed as a potential oral treatment for multiple sclerosis (MS) by sanofi-aventis, is the active metabolite of the rheumatoid arthritis drug leflunomide. Both teriflunomide and leflunomide are inhibitors of the mitochondrial enzyme dihydroorotate dehydrogenase, which is critically involved in pyrimidine synthesis. The production of activated T-cells largely depends on de novo pyrimidine synthesis, and thus pyrimidine depletion is thought to result in the inhibition of immune cell proliferation...

Biopharmaceutical approaches have been used to target key elements in the processes controlling airway inflammation in asthma and COPD. There is compelling evidence that IL-13 is a key mediator in the inflammatory processes in the asthmatic lung. Tralokinumab (CAT-354), under development by MedImmune, is an injectable, anti-IL-13 humanized mAb for the potential treatment of asthma and COPD. In a study in mice, tralokinumab prevented the development of the asthmatic phenotype, including eosinophil recruitment and airway hyperresponsiveness...

Advances in immunology and genetics have identified new therapeutic targets to control inflammation and symptoms in patients with inflammatory bowel diseases (IBD). Despite the success of anti-TNF therapies in the treatment of IBD, a considerable proportion of patients are refractory to treatment, highlighting an unmet medical need for new therapies. Molecules that direct the trafficking of inflammatory cells, such as the α4β7 integrin, are attractive targets for new drug candidates. The α4β7 integrin is involved in lymphocyte recruitment to the normal and inflamed gut mucosa, and the lymphoid tissue...

In asthma, airway inflammation is driven by Th2-related cytokines, such as IL-4, IL-5 and IL-13. IL-4 and IL-13, in particular, have a major role in the development of airway hyperresponsiveness, allergen-specific IgE synthesis and airway remodeling because of their synergistic effects induced by binding to the IL-4Rα subunit. Pitrakinra (AER-001, BAY-16-9996), being developed by Aerovance, under license from Bayer, for the potential treatment of asthma and eczema, is an IL-4 mutein, which binds to the IL-4Rα subunit and prevents the inflammation induced by IL-4 and IL-13...