Manav Malhotra

Aflibercept: a novel VEGF targeted agent to explore the future perspectives of anti-angiogenic therapy for the treatment of multiple tumors.

Angiogenesis is the process of formation of new blood vessels due to over expression of VEGF (vascular endothelial growth factor) which plays a critical role in the growth and development of all solid tumor types. With the advancement in understanding of tumor angiogenesis and VEGF, there have been a number of agents developed to target VEGF for the treatment of cancer. These targeted agents can affect downstream VEGF signal transduction by unique mechanisms at different cellular and extracellular levels. FDA has recently approved Aflibercept or VEGF-Trap in August 2012 for the treatment of colorectal cancer. It is a recombinant, decoy receptor fusion protein, rationally designed to block angiogenesis by targeting VEGF-A, VEGF-B and placental growth factor. VEGF-Trap exerts its antiangiogenic effects through regression of tumor vasculature, remodelling or normalization of surviving vasculature and inhibition of new tumor vessel growth. In this review, pre-clinical and clinical data have been summarized for aflibercept alone and in combination with chemotherapy to explore its efficacy and benefits in ovarian cancer, breast cancer, non-small cell lung cancer, pancreatic cancer, glioblastoma, adenocarcinoma and renal cell cancer xenograft models.

Design, synthesis and ex-vivo release studies of colon-specific polyphosphazene–anticancer drug conjugates

Colon-specific azo based polyphosphazene-anticancer drug conjugates (11-18) have been synthesized and evaluated by ex-vivo release studies. The prepared polyphosphazene drug conjugates (11-18) are stable in acidic (pH=1.2) buffer which showed that these polymer drug conjugates are protected from acidic environment which is the primary requirement of colon specific targeted drug delivery. The ex-vivo release profiles of polyphosphazene drug conjugates (11-18) have been performed in the presence as well as in the absence of rat cecal content. The results showed that more than 89% of parent drugs (methotrexate and gemcitabine) are released from polymeric backbone of polyphosphazene drug conjugates (14 and 18) having n-butanol (lipophilic moiety). The in-vitro cytotoxicity assay has also been performed which clearly indicated that these polymeric drug conjugates are active against human colorectal cancer cell lines (HT-29 and COLO 320 DM). The drug release kinetic study demonstrated that Higuchis equation is found to be best fitted equation which showed that release of drug from polymeric backbone as square root of time dependent process based on non-fickian diffusion. Therefore, the synthesized polyphosphazene azo based drug conjugates of methotrexate and gemcitabine are the potential candidates for colon targeted drug delivery system with minimal undesirable side effects.

Design, synthesis and ex vivo evaluation of colon-specific azo based prodrugs of anticancer agents.

Colon-specific azo based prodrugs of anticancer agents like methotrexate (6), gemcitabine (7) and analogue of oxaliplatin (RTB-4) (8) were synthesized and characterized by modern analytical techniques. The prepared prodrugs were stable in acidic (pH 1.2) and basic (pH 7.4) buffers which showed their stability in upper GIT environment. Further, an assay was performed which demonstrated the presence of azoreductase enzyme in the rat fecal material, rat cecum content and other parts of intestinal content which reduce specifically the azo bond and release the drug. The in vitro cytotoxicity assay was also performed which clearly indicated that these azo based prodrugs are active against human colorectal cancer cell lines (COLO 205, COLO 320 DM and HT-29). The release behavior of prodrugs (10, 11 and 15) was 60-70% after 24h incubation at 37°C. Therefore, the synthesized azo linked prodrugs of methotrexate, gemcitabine and RTB-4 are the potential candidates for colon targeted drug delivery system with minimal undesirable side effects.

Cabazitaxel: A Novel Drug for Hormone-Refractory Prostate Cancer

Cabazitaxel has recently been approved by FDA for the treatment of docetaxel resistant hormone-refractory prostate cancer. It has been developed by Sanofi-Aventis under the trade name of Jevtana. It is given in combination with prednisone/prednisolone and has passed the clinical trial over well-known drug mitoxantrone. This drug is a microtubule depolymerization inhibitor, which can penetrate blood brain barrier (BBB). The FDA granted fast track designation to this drug in November 2009 and thereafter, new drug application submission was done in March 2010. Priority review to this drug was granted in April 2010 and finally in July 2010 it was approved by FDA. It is available in the form of injection in the dose of 60 mg/1.5 mL, which should be diluted prior to its use by the diluents supplied along with the injection. It is a second-line drug and has proven to be effective in patients experiencing docetaxel based treatment failure.

Enzalutamide: a novel anti-androgen with prolonged survival rate in CRPC patients.

Prostate cancer is the most common malignancy among men found to be the second leading cause of male cancer-related mortality due to development of resistance against androgen deprivation therapy (ADT). With the advancement in understanding of prostate cancer, numbers of agents have been emerged to target Androgen-Receptor (AR) signaling for the treatment of castration resistant prostate cancer (CRPC). Food and Drug Administration (FDA) has recently approved enzalutamide (XTANDI) for the treatment of CRPC. Androgen receptor promotes the prostate cancer progression after transformation. Androgen receptor signaling leads to CRPC when cellular nucleus binds to DNA and increases pro cancer gene expression. In phase ΙΙΙ clinical trial, enzalutamide showed that 160 mg once daily oral administration is well tolerated and significantly enhanced overall survival in men with CRPC after chemotherapy, demonstrated by reduction in the serum prostate specific antigen (PSA) level and increased survival rate by 4.8 months.

Synthesis, characterization and antimicrobial evaluation of novel derivatives of isoniazid

In the present investigation, a series of new Mannich bases were prepared by the reaction of 2-ethoxybenzaldehyde with isoniazid to form acid hydrazone (3a). Further, C-Mannich bases of the above acid hydrazone were prepared by aminomethylation with formaldehyde and substituted secondary amines (3b–3k). The structures of newly synthesized compounds were evaluated by elemental analyses and spectral (IR, 1H NMR, 13C NMR) studies. All the synthesized compounds were evaluated for their antimicrobial activity. Amoxicillin was used as a standard drug for antibacterial activity while Nystatin was used as a standard drug for antifungal activity. Preliminary pharmacological evaluation revealed that the compound (3f, 3i, 3j, 3k) showed better performance against Bacillus subtilis,Staphylococcus aureus,Pseudomonas aeruginosa, Escherichia coli, Candida albicans and Candida gabrata. The result demonstrates the potential and importance of developing new mannich bases which would be effective against resistant bacterial and fungal strain.

Synthesis, characterization and anticancer activity of 3-aza-analogues of DP-7

From the recent studies, 3,5-dibenzoyl-1,4-dihydropyridone (DHP) derivatives, DP-7, has emerged as a potent multidrug reverting agent that inhibits efflux of drug from cell wall by inhibiting the activity of ATP Binding Cassettes. On the other hand, dihydropyrimidine (DHPM) derivative, (aza analogue) namely, monastrol inhibits the protein Eg5, which is responsible for the separation of daughter chromosomes during cell division and controls the growth of the tumor cells. In the present report, we have reported the hybridize molecules of these two potent molecules to check the dual action in cancer chemotherapy by synthesizing various thio and oxo analogues, bearing substituted aryl groups at 4th position of the DHPM ring. The newly synthesized molecules were screened for antiproliferative effects in mdr1-gene transfected mouse lymphoma cell line (l5178 y). Among these newly synthesized compounds namely, IIh, Ig, Ii, and Ij showed a very potent antiproliferative activity.

Synthesis, Characterization of (E)-N'-(substituted-benzylidene)isonicotinohydrazide Derivatives as Potent Antitubercular Agents

A series of 19 isonicotinic acid hydrazide derivatives has been synthesized and evaluated for their in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv using alamar blue susceptibility test. The synthesized compounds inhibit Mycobacterium tuberculosis H37Rv strain with minimum inhibitory concentration ranging from (0.00014-0.01174 mM). Among all synthesized compounds seven derivatives 2a, 2b, 2e, 2h, 2l, 2m and 2q were more potent than isoniazid and the compound 2q emerged as the most potent derivative, being more effective than isoniazid with an (MIC 0.00023 mM) in vitro. The results demonstrated the potential and importance of developing new isoniazid derivatives against Mycobacterium infections.

Target Based Designing of Anthracenone Derivatives as Tubulin Polymerization Inhibiting Agents: 3D QSAR and Docking Approach

Novel anthracenone derivatives were designed through in silico studies including 3D QSAR, pharmacophore mapping, and molecular docking approaches. Tubulin protein was explored for the residues imperative for activity by analyzing the binding pattern of colchicine and selected compounds of anthracenone derivatives in the active domain. The docking methodology applied in the study was first validated by comparative evaluation of the predicted and experimental inhibitory activity. Furthermore, the essential features responsible for the activity were established by carrying out pharmacophore mapping studies. 3D QSAR studies were carried out for a series of 1,5- and 1,8-disubstituted10-benzylidene-10H-anthracen-9-ones and 10-(2-oxo-2-phenylethylidene)-10H-anthracen-9-one derivatives for their antiproliferation activity. Based on the pattern recognition studies obtained from QSAR results, ten novel compounds were designed and docked in the active domain of tubulin protein. One of the novel designed compounds “N1” exhibited binding energy −9.69 kcal/mol and predicted Ki 78.32 nM which was found to be better than colchicine.

Synthesis, characterization of (Z)-N-(1-(2-(2-amino-3-(dimethylamino) methyl)phenyl)-5-phenyl-1,3,4, oxadiazol-3(2H)-yl)ethanone analogs as potent antimicrobial and hydrogen peroxide scavenging agents.

A series of (Z)-N-(1-(2-(2-amino-3-((dimethylamino) methyl) phenyl)-5-phenyl-1,3,4,oxadiazol-3(2H)- yl)ethanone derivatives was prepared and studied for its antimicrobial and antioxidant activities. Among the synthesized derivatives, compounds (7c) (Z)-N-(1-(2-(2-amino-3-((dimethylamino)methyl)phenyl)-5-phenyl-1,3,4-oxadiazol-3(2H)- yl)ethylidene)-4-chloroaniline, (7g) (Z)-N-(1-(2-(2-amino-3-((dimethylamino)methyl)phenyl)-5-phenyl-1,3,4-oxadiazol- 3(2H)-yl)ethylidene)-4-nitroaniline and (7i) (Z)-N-(1-(2-(2-amino-3-((dimethylamino)methyl)phenyl)-5-phenyl-1,3,4- oxadiazol-3(2H)-yl)ethylidene)-4-methoxyaniline were found to be the most effective antimicrobial compounds. While the compounds 7c and 7g were the most potent antioxidant compounds with significant hydrogen peroxide scavenging activity.