Evaluation of in vitro effects of various targeted drugs on plasma cells and putative neoplastic stem cells in patients with multiple myeloma

Research strategies of small molecules as chemotherapeutics to overcome multiple myeloma resistance

Multiple myeloma (MM), a cancer of plasma cells, is the second most common hematological malignancy which is characterized by aberrant plasma cells infiltration in the bone marrow and complex heterogeneous cytogenetic abnormalities. Over the past two decades, novel treatment strategies such as proteasome inhibitors, immunomodulators, and monoclonal antibodies have significantly improved the relative survival rate of MM patients. However, the development of drug resistance results in the majority of MM patients suffering from relapse, limited treatment options and uncontrolled disease progression after relapse. There are urgent needs to develop and explore novel MM treatment strategies to overcome drug resistance and improve efficacy. Here, we review the recent small molecule therapeutic strategies for MM, and introduce potential new targets and corresponding modulators in detail. In addition, this paper also summarizes the progress of multi-target inhibitor therapy and protein degradation technology in the treatment of MM.

Comprehensive review for anticancer hybridized multitargeting HDAC inhibitors

Despite the encouraging clinical progress of chemotherapeutic agents in cancer treatment, innovation and development of new effective anticancer candidates still represents a challenging endeavor. With 15 million death every year in 2030 according to the estimates, cancer has increased rising of an alarm as a real crisis for public health and health systems worldwide. Therefore, scientist began to introduce innovative solutions to control the cancer global health problem. One of the promising strategies in this issue is the multitarget or smart hybrids having two or more pharmacophores targeting cancer. These rationalized hybrid molecules have gained great interests in cancer treatment as they are capable to simultaneously inhibit more than cancer pathway or target without drug-drug interactions and with less side effects. A prime important example of these hybrids, the HDAC hybrid inhibitors or referred as multitargeting HDAC inhibitors. The ability of HDAC inhibitors to synergistically improve the efficacy of other anti-cancer drugs and moreover, the ease of HDAC inhibitors cap group modification prompt many medicinal chemists to innovate and develop new generation of HDAC hybrid inhibitors. Notably, and during this short period, there are four HDAC inhibitor hybrids have entered different phases of clinical trials for treatment of different types of blood and solid tumors, namely; CUDC-101, CUDC-907, Tinostamustine, and Domatinostat. This review shed light on the most recent hybrids of HDACIs with one or more other cancer target pharmacophore. The designed multitarget hybrids include topoisomerase inhibitors, kinase inhibitors, nitric oxide releasers, antiandrogens, FLT3 and JAC-2 inhibitors, PDE5-inhibitors, NAMPT-inhibitors, Protease inhibitors, BRD4-inhibitors and other targets. This review may help researchers in development and discovery of new horizons in cancer treatment.

Design, synthesis, and bioactivity evaluation of novel Bcl-2/HDAC dual-target inhibitors for the treatment of multiple myeloma

Multiple myeloma (MM) is the second most common haematological malignancy. Almost all patients with MM eventually relapse, and most recommended treatment protocols for the patients with relapsed refractory MM comprise a combination of drugs with different mechanisms of action. Therefore novel drugs are in urgent need in clinic. Bcl-2 inhibitors and HDAC inhibitors were proved their anti-MM effect in clinic or under clinical trials, and they were further discovered to have synergistic interactions. In this study, a series of Bcl-2/HDAC dual-target inhibitors were designed and synthesized. Among them, compounds 7e-7g showed good inhibitory activities against HDAC6 and high binding affinities to Bcl-2 protein simultaneously. They also displayed good growth inhibitory activities against human MM cell line RPMI-8226, which proved their potential value for the treatment of multiple myeloma.

Ionophores: Potential Use as Anticancer Drugs and Chemosensitizers

Ion homeostasis is extremely important for the survival of both normal as well as neoplastic cells. The altered ion homeostasis found in cancer cells prompted the investigation of several ionophores as potential anticancer agents. Few ionophores, such as Salinomycin, Nigericin and Obatoclax, have demonstrated potent anticancer activities against cancer stem-like cells that are considered highly resistant to chemotherapy and responsible for tumor relapse. The preclinical success of these compounds in in vitro and in vivo models have not been translated into clinical trials. At present, phase I/II clinical trials demonstrated limited benefit of Obatoclax alone or in combination with other anticancer drugs. However, future development in targeted drug delivery may be useful to improve the efficacy of these compounds. Alternatively, these compounds may be used as leading molecules for the development of less toxic derivatives.

Cross Talk Networks of Mammalian Target of Rapamycin Signaling With the Ubiquitin Proteasome System and Their Clinical Implications in Multiple Myeloma

Multiple myeloma (MM) is the second most common hematological malignancy and results from the clonal amplification of plasma cells. Despite recent advances in treatment, MM remains incurable with a median survival time of only 5-6years, thus necessitating further insights into MM biology and exploitation of novel therapeutic approaches. Both the ubiquitin proteasome system (UPS) and the PI3K/Akt/mTOR signaling pathways have been implicated in the pathogenesis, and treatment of MM and different lines of evidence suggest a close cross talk between these central cell-regulatory signaling networks. In this review, we outline the interplay between the UPS and mTOR pathways and discuss their implications for the pathophysiology and therapy of MM.

Ludwig Boltzmann Cluster Oncology (LBC ONC): first 10 years and future perspectives

In 2008 the Ludwig Boltzmann Cluster Oncology (LBC ONC) was established on the basis of two previous Ludwig Boltzmann Institutes working in the field of hematology and cancer research. The general aim of the LBC ONC is to improve treatment of hematopoietic neoplasms by eradicating cancer-initiating and disease-propagating cells, also known as leukemic stem cells (LSC) in the context of leukemia. In a first phase, the LBC ONC characterized the phenotype and molecular aberration profiles of LSC in various malignancies. The LSC phenotypes were established in acute and chronic myeloid leukemia, in acute lymphoblastic leukemia and in chronic lymphocytic leukemia. In addition, the concept of preleukemic (premalignant) neoplastic stem cells (pre-L-NSC) was coined by the LBC ONC and was tested in myelodysplastic syndromes and myeloproliferative neoplasms. Phenotypic characterization of LSC provided a solid basis for their purification and for the characterization of specific target expression profiles. In a second phase, molecular markers and targets were validated. This second phase is ongoing and should result in the development of new diagnostics parameters and novel, more effective, LSC-eradicating, treatment strategies; however, many issues still remain to be solved, such as sub-clonal evolution, LSC niche interactions, immunologic control of LSC, and LSC resistance. In the forthcoming years, the LBC ONC will concentrate on developing LSC-eradicating strategies, with special focus on LSC resistance, precision medicine and translation of LSC-eradicating concepts into clinical application.

The therapeutic potential of cell cycle targeting in multiple myeloma

Proper cell cycle progression through the interphase and mitosis is regulated by coordinated activation of important cell cycle proteins (including cyclin-dependent kinases and mitotic kinases) and several checkpoint pathways. Aberrant activity of these cell cycle proteins and checkpoint pathways results in deregulation of cell cycle progression, which is one of the key hallmarks of cancer. Consequently, intensive research on targeting these cell cycle regulatory proteins identified several candidate small molecule inhibitors that are able to induce cell cycle arrest and even apoptosis in cancer cells. Importantly, several of these cell cycle regulatory proteins have also been proposed as therapeutic targets in the plasma cell malignancy multiple myeloma (MM). Despite the enormous progress in the treatment of MM the past 5 years, MM still remains most often incurable due to the development of drug resistance. Deregulated expression of the cyclins D is observed in virtually all myeloma patients, emphasizing the potential therapeutic interest of cyclin-dependent kinase inhibitors in MM. Furthermore, other targets have also been identified in MM, such as microtubules, kinesin motor proteins, aurora kinases, polo-like kinases and the anaphase promoting complex/cyclosome. This review will provide an overview of the cell cycle proteins and checkpoint pathways deregulated in MM and discuss the therapeutic potential of targeting proteins or protein complexes involved in cell cycle control in MM.