Vijay Ramakrishnan

Bortezomib Combination Therapy in Multiple Myeloma

Bortezomib was approved for the treatment of multiple myeloma (MM) in 2003. Since then several bortezomib-based combination therapies have emerged. Although some combinations have been preceded by preclinical investigations, most have followed the inevitable process in which active (or potentially active) drugs are combined with each other to create new treatment regimens. Regimens that have combined bortezomib with corticosteroids, alkylating agents, thalidomide, and/or lenalidomide have resulted in high response rates. Despite the higher and often deeper response rates and prolongation of progression-free survival with bortezomib-based multiagent regimens, an overall survival (OS) advantage has not been demonstrated with most combinations compared to the sequential approach of using anti-myeloma agents, particularly in patients less than 65 years of age with newly diagnosed myeloma. The unique properties of some of these regimens can be taken into account when choosing a particular regimen based on the clinical scenario. For example, the combination of bortezomib, thalidomide, and dexamethasone (VTD) has particular value in renal failure since none of the drugs need dose modification. Similarly, the combination chemotherapy regimen VDT-PACE (bortezomib, dexamethasone, thalidomide, cisplatin, doxorubicin, cyclophosphamide, and etoposide) is of particular value in patients presenting with aggressive disease such as extramedullary plasmacytomas or plasma cell leukemia. Ongoing clinical trials are testing combinations of bortezomib with several other classes of agents, including monoclonal antibodies, and inhibitors of deacetylases, heat shock proteins, phosphatidyl inositol 3-kinase/Akt/mammalian target of rapamycin pathway and farnesyl transferase.

TG101209, a novel JAK2 inhibitor, has significant in vitro activity in multiple myeloma and displays preferential cytotoxicity for CD45+ myeloma cells†

Interaction of myeloma cells with the bone marrow microenvironment is mediated in large part through different cytokines, especially VEGF and IL6. These cytokines, especially IL6, leads to upregulation of the JAK/STAT pathway in myeloma cell, contributing to increased proliferation, decreased apoptosis, and acquired drug resistance. Here, we examined the preclinical activity of a novel JAK2 inhibitor TG101209. TG101209 induced dose‐ and time‐dependent cytotoxicity in a variety of multiple myeloma (MM) cell lines. The induction of cytotoxicity was associated with inhibition of cell cycle progression and induction of apoptosis in myeloma cell lines and patient‐derived plasma cells. Evaluation of U266 cell lines and patient cells, which have a mix of CD45 positive and negative cells, demonstrated more profound cytotoxicity and antiproliferative activity of the drug on the CD45+ population relative to the CD45− cells. Exploring the mechanism of action of TG101209 indicated downregulation of pJak2, pStat3, and Bcl‐xl levels with upregulation of pErk and pAkt levels indicating cross talk between signaling pathways. TG101209, when used in combination with the PI3K inhibitor LY294002, demonstrated synergistic cytotoxicity against myeloma cells. Our results provide the rationale for clinical evaluation of TG101209 alone or in combination with PI3K/Akt inhibitors in MM. Am. J. Hematol., 2010.

Anti-Myeloma Activity of Akt Inhibition Is Linked to the Activation Status of PI3K/Akt and MEK/ERK Pathway

The PI3K/Akt/mTOR signal transduction pathway plays a central role in multiple myeloma (MM) disease progression and development of therapeutic resistance. mTORC1 inhibitors have shown limited efficacy in the clinic, largely attributed to the reactivation of Akt due to rapamycin induced mTORC2 activity. Here, we present promising anti-myeloma activity of MK-2206, a novel allosteric pan-Akt inhibitor, in MM cell lines and patient cells. MK-2206 was able to induce cytotoxicity and inhibit proliferation in all MM cell lines tested, albeit with significant heterogeneity that was highly dependent on basal pAkt levels. MK-2206 was able to inhibit proliferation of MM cells even when cultured with marrow stromal cells or tumor promoting cytokines. The induction of cytotoxicity was due to apoptosis, which at least partially was mediated by caspases. MK-2206 inhibited pAkt and its down-stream targets and up-regulated pErk in MM cells. Using MK-2206 in combination with rapamycin (mTORC1 inhibitor), LY294002 (PI3K inhibitor), or U0126 (MEK1/2 inhibitor), we show that Erk- mediated downstream activation of PI3K/Akt pathway results in resistance to Akt inhibition. These provide the basis for clinical evaluation of MK-2206 alone or in combination in MM and potential use of baseline pAkt and pErk as biomarkers for patient selection.

Sorafenib, a multikinase inhibitor, is effective in vitro against non-hodgkin lymphoma and synergizes with the mTOR inhibitor rapamycin†

Non‐Hodgkin lymphoma (NHL) represents a heterogenous group of neoplasias originating from lymphoid cells. Increased angiogenesis and expression of Vascular Endothelial Growth Factor (VEGF) and its receptors (VEGFR) have been found to be associated with NHL disease progression. Increase in VEGF and other cytokines stimulate signaling cascades, including the Ras/Raf/Mek/Erk pathway, resulting in increased proliferation and decreased apoptosis. Here, we report the in vitro antilymphoma activity of sorafenib, an inhibitor of VEGFR and Raf kinase. Sorafenib induced potent cytotoxicity in NHL cell lines and patient samples. This induction of cytotoxicity was associated with a corresponding increase in apoptotic cell death. Mechanism of action of sorafenib was investigated in follicular (DoHH2) and Burkitt lymphoma (Raji) cell lines. pStat3, pAkt, Mcl1, and Xiap were downregulated in both cell lines, whereas pErk decreased in Raji but not in DoHH2 cells following sorafenib treatment. IL6 was unable to prevent sorafenib induced repression of pStat3, pAkt, Mcl1, and Bcl‐Xl. Sorafenib in combination with an mTORC1 inhibitor rapamycin demonstrated synergy in inducing cytotoxicity in NHL cells. Sorafenib/rapamycin combination resulted in downregulation of pAkt, pmTOR, p‐p70S6K, p4EBP1, pGSK3β, Mcl1, and Bcl‐Xl. On the basis of our results, a clinical trial is underway using sorafenib with everolimus in NHL patients., 2012.

Global Variation of Human Papillomavirus Genotypes and Selected Genes Involved in Cervical Malignancies.

BACKGROUND Carcinoma of the cervix is ranked second among the top 5 cancers affecting women globally. Parallel to other cancers, it is also a complex disease involving numerous factors such as human papillomavirus (HPV) infection followed by the activity of oncogenes and environmental factors. The incidence rate of the disease remains high in developing countries due to lack of awareness, followed by mass screening programs, various socioeconomic issues, and low usage of preventive vaccines. Over the past 3 decades, extensive research has taken place in cervical malignancy to elucidate the role of host genes in the pathogenesis of the disease, yet it remains one of the most prevalent diseases. It is imperative that recent genome-wide techniques be used to determine whether carcinogenesis of oncogenes is associated with cervical cancer at the molecular level and to translate that knowledge into developing diagnostic and therapeutic tools. OBJECTIVE The aim of this study was to discuss HPV predominance with their genotype distribution worldwide, and in India, as well as to discuss the newly identified oncogenes related to cervical cancer in current scenario. FINDINGS Using data from various databases and robust technologies, oncogenes associated with cervical malignancies were identified and are explained in concise manner. CONCLUSION Due to the advent of recent technologies, new candidate genes are explored and can be used as precise biomarkers for screening and developing drug targets.

Clinical use and applications of histone deacetylase inhibitors in multiple myeloma

The incorporation of various novel therapies has resulted in a significant survival benefit in newly diagnosed and relapsed patients with multiple myeloma (MM) over the past decade. Despite these advances, resistance to therapy leads to eventual relapse and fatal outcomes in the vast majority of patients. Hence, there is an unmet need for new safe and efficacious therapies for continued improvement in outcomes. Given the role of epigenetic aberrations in the pathogenesis and progression of MM and the success of histone deacetylase inhibitors (HDACi) in other malignancies, many HDACi have been tried in MM. Various preclinical studies helped us to understand the antimyeloma activity of different HDACi in MM as a single agent or in combination with conventional, novel, and immune therapies. The early clinical trials of HDACi depicted only modest single-agent activity, but recent studies have revealed encouraging clinical response rates in combination with other antimyeloma agents, especially proteasome inhibitors. This led to the approval of the combination of panobinostat and bortezomib for the treatment of relapsed/refractory MM patients with two prior lines of treatment by the US Food and Drug Administration. However, it remains yet to be defined how we can incorporate HDACi in the current therapeutic paradigms for MM that will help to achieve longer disease control and significant survival benefits. In addition, isoform-selective and/or class-selective HDAC inhibition to reduce unfavorable side effects needs further evaluation.

Association between MDR1 gene polymorphisms and Parkinson's disease in Asian and Caucasian populations: a meta-analysis.

Parkinsons disease (PD) is a complex neurodegenerative disease, its etiology is largely unknown. Studies demonstrate the association of genetic and environment factors in causing neuronal degeneration. Reports suggest that the multi-drug resistance gene (MDR1) plays a vital role in preventing the toxic substance in entering the brain, which is associated with PD. However, the association between the MDR1 polymorphisms (C1236T and C3435T) and its susceptibility to PD is inconclusive. Meta analysis was carried by retrieving literatures from databases to search the case-control studies on the associations between the MRD1 polymorphisms and PD. The pooled odds ratios (ORs) and its 95% confidence intervals (CIs) were calculated using fixed and random model to determine the association between the polymorphisms and PD susceptibility. Significant association was noticed for C1236T polymorphism and PD risk in the recessive model OR=0.80, 95% CI=0.66-0.97. Further, ethnicity based analysis showed significant association for C1236T in allelic model of Asian population and also in the recessive models of both Asian and Caucasian populations. However, insignificant associations were noticed for C3435T in all the four models. Overall, the analysis suggested that MDR1 C1236T polymorphism substantially contribute to Parkinsons disease in the recessive genetic model.

Genetic predisposition of IL-10 promoter polymorphisms with risk of multiple sclerosis: A meta-analysis

Interleukin-10 (IL-10) is a anti-inflammatory cytokine, which controls inflammation by inhibiting the synthesis of several cytokines produced by Th1 cells and macrophages. The association between Interleukin-10 promoter polymorphisms with the risk of multiple sclerosis (MS) remains inconclusive. In this study, a meta-analysis has been performed to assess the relationship between IL-10 gene polymorphisms rs1800896, rs1800871 and rs1800872 with the risk of MS. Nine case-control studies were selected involving 2755 participants. The association between the polymorphisms and MS was examined by the pooled odds ratios (ORs) with 95% confidence intervals (CIs) in allelic, homozygote, heterozygote, dominant and recessive genetic models. Of analyzed genetic models, the pooled ORs and CIs of each SNPs calculated based on random (I2>50) or fixed effects (I2<50) methods, which showed no significant association (p-value>0.05) of genetic predisposition with MS susceptibility across Asian and Caucasian populations. In addition, assessment based on funnel plot and Eggers linear regression test suggests no publication bias in all analyzed genetic models. Overall, our results demonstrated that rs1800896, rs1800871 and rs1800872 polymorphisms may not be the risk factor for the development of MS in both the populations.

Signaling Pathways and Emerging Therapies in Multiple Myeloma.

Multiple myeloma (MM) is a devastating malignancy of antibody-producing plasma cells. In the absence of a single unifying genetic event contributing to disease manifestation, efforts have focused on understanding signaling events deregulated in myeloma plasma cells. MM cells are dependent on both cellular and non-cellular components of the tumor microenvironment such as bone marrow stromal cells, endothelial cells, and cytokines such as interleukin 6 (IL6), vascular endothelial growth factor (VEGF), and insulin-like growth factor (IGF) for their growth and survival. The cumulative effect of such interactions is the aberrant activation of numerous signal transduction pathways within the MM plasma cells leading to uncontrolled growth and prevention of apoptosis. Here, we will review our current understanding of some of the key signal transduction pathways dysregulated in MM and emerging therapies targeting these pathways in MM.

Multiple mechanisms contribute to the synergistic anti-myeloma activity of the pan-histone deacetylase inhibitor LBH589 and the rapalog RAD001

We examined the pre-clinical activity of pan-histone deacetylase inhibitor LBH589 in combination with mTORC1 inhibitor RAD001 and observed that the drug combination strongly synergized in inducing cytotoxicity in multiple myeloma (MM) cells. LBH589 caused an increase in acetylated histones and RAD001 inhibited mTORC1 activity. RAD001 caused potent G0/G1 arrest while LBH589 induced pronounced apoptosis, both of which were enhanced when the drugs were used in combination. LBH589/RAD001 combination led to down regulation of pStat3, cyclins, CDKs and XIAP and up regulation of pro-apoptotic Bcl-2 family proteins. A clinical trial is underway using LBH589/RAD001 combination in relapsed MM patients.