Edelfosine is a synthetic alkyl-lysophospholipid, a potent immunomodulator and an effective inhibitor of tumor cell proliferation. The cytotoxic effect of edelfosine has been evaluated in a large variety of both tumor (leukemic and solid) and normal cell types, showing a high degree of selectivity towards tumor cells. Like all alkyl-lysophospholipids, Edelfosine incorporates into the cell membrane and does not target the DNA. In many tumor cells, Edelfosine causes selective apoptosis, sparing healthy cells. Edelfosine can activate the Fas/CD95cell death receptor, can inhibit the MAPK/ERK mitogenic pathway and the Akt/protein kinase B (PKB) survival pathway. Edelfosine apoptosis-inducing abilities were studied with several types of cancer, among them multiple myeloma and non-small and small cell lung carcinoma cell lines. In vivo activity against human solid tumors in mice was shown against malignant gynecological tumor cells, like ovarian cancer, and against breast cancer. In vivo biodistribution studies demonstrated a “considerably higher” accumulation of Edelfosine in tumor cells than in other analyzed organs. Several clinical trials were conducted. Among them, a phase I trials with solid tumors or leukemias and phase II with non-small-cell lung carcinomas (NSCLC). In Phase II clinical trial for use of Edelfosine in treating leukemia with bone marrow transplants, it was found to be safe and 'possibly effective'. A phase II trial for the treatment of brain cancers was also reported. It showed encouraging results in stopping the growth of the tumor and a considerable improvement in the “quality of life” of the patients. A phase II trial on the effect of Edelfosine on advanced non-small-cell bronchogenic carcinoma had a “remarkable” “high proportion of patients with stationary tumor status” as result, stable disease after initial progression in 50% of the patients.

Agouron (Pfizer) was developing AG-24322 (AG-024322), a small-molecule cyclin-dependent kinase (CDK) inhibitor, for the treatment of cancer. AG-024322 is a potent inhibitor of CDK1, CDK2, and CDK4 that produces cell-cycle arrest and antitumor activity in preclinical models. AG-24322 is a potent ATP-competitive inhibitor of CDK1, CDK2, and CDK4 with Ki values in the 2–3 nM range and selectivity over other non-CDKs. This compound has been shown to inhibit Rb phosphorylation in cells, elicit cell-cycle arrest, and have antiproliferative activity in multiple human tumor cell lines (IC50 values from 30 to 200 nM). AG-24322 was reported to be undergoing phase I trials for cancer in the US, however the development was discontinued.

CC-401 is a potent inhibitor of all three forms of c-Jun N-terminal Kinase (JNK) (Ki of 25 to 50 nM) and has at least 40-fold selectivity for JNK compared with other related kinases. Celgene was developing CC 401 for the treatment of cancer and inflammatory disorders. CC 401 was being developed in an IV formulation and was in a phase I trial in patients with refractory acute myelogenous leukaemia. However, trials have ended and the company is not pursuing CC 401, but will advance other JNK inhibitors.

AZD1775 selectively targets and inhibits WEE1, a tyrosine kinase that phosphorylates cyclin-dependent kinase 1 (CDK1, CDC2) to inactivate the CDC2/cyclin B complex. Inhibition of WEE1 activity prevents the phosphorylation of CDC2 and impairs the G2 DNA damage checkpoint. This may lead to apoptosis upon treatment with DNA damaging chemotherapeutic agents. Current ongoing trials of AZD1775 include monotherapy and combination therapy with certain DNA damaging agents in solid tumors, ovarian tumors, gynaecological cancer, non-small cell lung cancer. AZD1775 is genotoxic, which is considered to be a result of its mechanism of action. Common serious adverse events (with chemotherapy) include: febrile neutropenia, neutropenia, thrombocytopenia.

Pelitinib (EKB-569) is a 3-cyanoquinoline pan-ErbB tyrosine kinase inhibitor with potential antineoplastic activity. Pelitinib irreversibly binds covalently to epidermal growth factor receptors, thereby inhibiting receptor phosphorylation and signal transduction and resulting in apoptosis and suppression of proliferation in tumor cells that overexpress these receptors. Pelitinib had been in phase II clinical trials for the treatment of non-small cell lung cancer and colorectal cancer. Treatment-emergent adverse events were diarrhea, abdominal pain, gastrointestinal carcinoma, intestinal obstruction and vomiting.

Emodin is a naturally occurring anthraquinone present in the roots of numerous plants and lichens and an active ingredient of various Chinese herbs. Emodin possesses various biological properties and serves as an anti-bacterial and anti-inflammatory agent. Emodin was studied as a potential anti-cancer agent: e.g., it was shown, that compound inhibits the invasion and migration of colon cancer cells in vitro and in vivo by blocking EMT, which is related with the inhibition of Wnt/β-catenin signaling pathway. Besides, emodin effectively ameliorates asthmatic airway inflammation and alternatively activated macrophages (AAMs) polarization, and thus can be a potential agent for the treatment of asthma. It is known that the Inhibition of AAMs is an alternative therapeutic strategy for treating asthma. Some experiments have revealed that emodin can be a beneficial dietary supplement in prolonging lifespan.

Picropodophyllin (also known as picropodophyllotoxin (PPP)), an orally active insulin-like growth factor 1 receptor (IGF1R) inhibitor that exhibits no activity at the insulin receptor, FGFR, PDGFR or EGFR. Picropodophyllin possesses antineoplastic activity. PPP is currently tested as an orally administrated single agent treatment in an open-label combined Phase I/II clinical study in advanced cancer patients with solid tumors which progress in spite of several lines of treatment. In addition, it effectively inhibits rhambodmyosarcomas tumor proliferation and metastasis in vitro and in an animal model.

U0126 is a highly selective inhibitor of both MEK1 and MEK2, a type of MAPK/ERK kinase. The inhibitory effects of U0126 on MEK and ERK activation have been confirmed repeatedly, and treatments with U0126 have been shown to inhibit proliferation and migration of cancer cells in vivo and in vitro. U0126 has been widely used as an inhibitor for the Ras/Raf/MEK/ERK signaling pathway. U0126 treatments lead to cancer cell death, which agrees with the well-known role of the Ras/Raf/MEK/ERK pathway in supporting cell survival. U0126 enhances apoptosis in human breast cancer MCF-7 cells, acute myeloid leukemia, and PC12 cells.

K-252a, a metabolite isolated from the culture broth of Nocardiopsis sp. K-252a, was found to exhibit an extremely potent inhibitory activity on protein kinase C. The IC50 value was 32.9 nM. K252a is a potent inhibitor of various protein kinases including Protein kinase A, Protein kinase C and Protein kinase G. It acts by competition with the ATP binding site with Ki values of 18-25 nM. K252a also acts as a specific and potent inhibitor (IC50 = 3 nM) of Trk receptors and thus selectively blocks the effects of nerve growth factor (NGF) on PC12 cells. At lower concentrations, K252a can act as a neuroprotective compound, promoting survival of primary neuronal cultures. This alkaloid induces apoptosis and cell cycle arrest by inhibiting Cdc2 and Cdc25.4 Recently, K252a was found to improve psoriasis in a SCID mouse-human skin model and to suppress referred mechanical hypersensitivity and neuropeptide up-regulation associated with acute pancreatitis.