maytansine and Disease-Models--Animal

While our understanding of tumors and how to treat them has advanced significantly since the days of Aminopterin and the radical mastectomy, cancer remains among the leading causes of death worldwide. Despite innumerable advancements in medical technology the non-static and highly heterogeneous nature of a tumor can make characterization and treatment exceedingly difficult. Because of this complexity, the identification of new cellular constituents that can be used for diagnostic, prognostic, and therapeutic purposes is crucial in improving patient outcomes worldwide. Growing evidence has demonstrated that among the myriad of changes seen in cancer cells, the Syndecan family of proteins has been observed to undergo drastic alterations in expression. Syndecans are transmembrane heparan sulfate proteoglycans that are responsible for cell signaling, proliferation, and adhesion, and many studies have shed light on their unique involvement in both tumor progression and suppression. This review seeks to discuss Syndecan expression levels in various cancers, whether they make reliable biomarkers for detection and prognosis, and whether they may be viable targets for future cancer therapies. The conclusions drawn from the literature reviewed in this article indicate that changes in expression of Syndecan protein can have profound effects on tumor size, metastatic capability, and overall patient survival rate. Further, while data regarding the therapeutic targeting of Syndecan proteins is sparse, the available literature does demonstrate promise for their use in cancer treatment going forward.

Topics: Animals; Biomarkers, Tumor; Cell Line, Tumor; Disease Models, Animal; Humans; Immunoconjugates; Immunotherapy, Adoptive; Maytansine; Mice; Neoplasms; Prognosis; Progression-Free Survival; Receptors, Chimeric Antigen; Survival Rate; Syndecans; Xenograft Model Antitumor Assays

SAR3419 is a novel anti-CD19 humanized monoclonal antibody conjugated to a maytansine derivate through a cleavable linker for the treatment of B-cell malignancies. SAR3419 combines the strengths of a high-potency tubulin inhibitor and the exquisite B-cell selectivity of an anti-CD19 antibody. The internalization and processing of SAR3419, following its binding at the surface of CD19-positive human lymphoma cell lines and xenograft models, release active metabolites that trigger cell-cycle arrest and apoptosis, leading to cell death and tumor regression. SAR3419 has also been shown to be active in different lymphoma xenograft models, including aggressive diffuse large B-cell lymphoma, resulting in complete regressions and tumor-free survival. In these models, the activity of SAR3419 compared favorably with rituximab and lymphoma standard of care chemotherapy. Two phase I trials with 2 different schedules of SAR3419 as a single agent were conducted in refractory/relapsed B-cell non-Hodgkin lymphoma. Activity was reported in both schedules, in heavily pretreated patients of both follicular and diffuse large B-cell lymphoma subtypes, with a notable lack of significant hematological toxicity, validating SAR3419 as an effective antibody-drug conjugate and opening opportunities in the future. Numerous B-cell-specific anti-CD19 biologics are available to treat B-cell non-Hodgkin lymphoma, and early phase I results obtained with SAR3419 suggest that it is a promising candidate for further development in this disease. In addition, thanks to the broad expression of CD19, SAR3419 may provide treatment options for B-cell leukemias that are often CD20-negative.

Topics: Animals; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antigens, CD19; Antineoplastic Agents, Phytogenic; Clinical Trials as Topic; Disease Models, Animal; Humans; Immunoconjugates; Leukemia, B-Cell; Lymphoma, B-Cell; Maytansine; Mice; Xenograft Model Antitumor Assays

HER2-positive breast cancer is heterogeneous. Some tumors express mutations, like activating PIK3CA mutations or reduced PTEN expression, that negatively correlate with response to HER2-targeted therapies. In this exploratory analysis, we investigated whether the efficacy of trastuzumab emtansine (T-DM1), an antibody-drug conjugate comprised of the cytotoxic agent DM1 linked to the HER2-targeted antibody trastuzumab, was correlated with the expression of specific biomarkers in the phase III EMILIA study.. Tumors were evaluated for HER2 (n = 866), EGFR (n = 832), and HER3 (n = 860) mRNA expression by quantitative reverse transcriptase PCR; for PTEN protein expression (n = 271) by IHC; and for PIK3CA mutations (n = 259) using a mutation detection kit. Survival outcomes were analyzed by biomarker subgroups. T-DM1 was also tested on cell lines and in breast cancer xenograft models containing PIK3CA mutations.. Longer progression-free survival (PFS) and overall survival (OS) were observed with T-DM1 compared with capecitabine plus lapatinib in all biomarker subgroups. PIK3CA mutations were associated with shorter median PFS (mutant vs. wild type: 4.3 vs. 6.4 months) and OS (17.3 vs. 27.8 months) in capecitabine plus lapatinib-treated patients, but not in T-DM1-treated patients (PFS, 10.9 vs. 9.8 months; OS, not reached in mutant or wild type). T-DM1 showed potent activity in cell lines and xenograft models with PIK3CA mutations.. Although other standard HER2-directed therapies are less effective in tumors with PI3KCA mutations, T-DM1 appears to be effective in both PI3KCA-mutated and wild-type tumors. Clin Cancer Res; 22(15); 3755-63. ©2016 AACR.

Topics: Ado-Trastuzumab Emtansine; Animals; Antineoplastic Agents, Immunological; Biomarkers, Tumor; Breast Neoplasms; Disease Models, Animal; Female; Follow-Up Studies; Humans; Kaplan-Meier Estimate; Maytansine; Mice; Neoplasm Metastasis; Neoplasm Staging; Phosphatidylinositol 3-Kinases; Proportional Hazards Models; Receptor, ErbB-2; Retreatment; Trastuzumab; Xenograft Model Antitumor Assays

Triple-negative breast cancers (TNBCs) are highly aggressive and metastatic. To date, finding efficacious targeted therapy molecules might be the only window of hope to cure cancer. Fibromodulin (FMOD), is ectopically highly expressed on the surface of Chronic Lymphocytic Leukemia (CLL) and bladder carcinoma cells; thus, it could be a promising molecule for targeted therapy of cancer. The objective of this study was to evaluate cell surface expression of FMOD in two TNBC cell lines and develop an antibody-drug conjugate (ADC) to target FMOD positive TNBC in vitro and in vivo.. Two TNBC-derived cell lines 4T1 and MDA-MB-231 were used in this study. The specific binding of anti-FMOD monoclonal antibody (mAb) was evaluated by flow cytometry and its internalization was verified using phAb amine reactive dye. A microtubulin inhibitor Mertansine (DM1) was used for conjugation to anti-FMOD mAb. The binding efficacy of FMOD-ADC was assessed by immunocytochemistry technique. The anti-FMOD mAb and FMOD-ADC apoptosis induction were measured using Annexin V-FITC and flow cytometry. Tumor growth inhibition of anti-FMOD mAb and FMOD-ADC was evaluated using BALB/c mice injected with 4T1 cells.. Our results indicate that both anti-FMOD mAb and FMOD-ADC recognize cell surface FMOD molecules. FMOD-ADC could induce apoptosis in 4T1 and MDA-MB-231 cells in vitro. In vivo tumor growth inhibition was observed using FMOD-ADC in 4T1 inoculated BALB/c mice.. Our results suggests high cell surface FMOD expression could be a novel bio-marker TNBCs. Furthermore, FMOD-ADC could be a promising candidate for targeting TNBCs.

Topics: Amines; Animals; Antibodies, Monoclonal; Cell Line, Tumor; Disease Models, Animal; Fibromodulin; Humans; Immunoconjugates; Maytansine; Mice; Triple Negative Breast Neoplasms

Hepatocellular carcinoma (HCC) is the sixth most common cancer worldwide with poor prognosis and limited options for treatment. Life expectancy after diagnosis is short; the currently available treatments are not well tolerated and have limited clinical benefit. There is a clear unmet clinical need for the development of new treatments. In this study, ultrasmall, 2 nm gold core nanoparticles (MidaCore) conjugated with the potent maytansine analogue DM1 (MTC-100038) were assessed as a systemic nanomedicine for the treatment of hepatocellular carcinoma. The platform improved overall tolerability of DM1, permitting ∼3-fold higher levels of drug to be administered compared to free drug. Dose for dose, MTC-100038 also facilitated delivery of ∼2.0-fold higher ( p = 0.039) levels of DM1 to the tumor compared to free DM1. MTC-100038 produced significant efficacy (tumor growth index ∼102%; p = <0.0001), in several murine xenograft models of HCC, and was superior to both free DM1 and the current standard of care, sorafenib. Furthermore, MTC-100038 displayed potent (nM) in vitro activity in various HCC primary patient derived cell lines and across various other different cancer cell types. These data demonstrate the potential of MidaCore nanoparticles to enhance tumor delivery of cytotoxic drugs and indicate MTC-100038 is worthy of further investigation as a potential treatment for HCC and other cancer types.

Topics: Animals; Antineoplastic Agents, Phytogenic; Carcinoma, Hepatocellular; Cell Line, Tumor; Disease Models, Animal; Drug Carriers; Female; Gold; Humans; Liver Neoplasms; Maytansine; Metal Nanoparticles; Mice; Mice, Inbred BALB C; Particle Size; Xenograft Model Antitumor Assays

Antibody-drug conjugates (ADC) are a novel way to deliver potent cytotoxic compounds to cells expressing a specific antigen. Four ADC targeting CD19, including SAR3419 (coltuximab ravtansine), have entered clinical development. Here, we present huB4-DGN462, a novel ADC based on the SAR3419 anti-CD19 antibody linked

Topics: Animals; Antibodies, Monoclonal, Humanized; Antigens, CD19; Antineoplastic Agents; Cell Line, Tumor; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Humans; Immunoconjugates; Leukemia; Lymphoma; Maytansine; Mice; Treatment Outcome; Xenograft Model Antitumor Assays

Antibody-drug conjugates (ADC) utilizing noncleavable linker drugs have been approved for clinical use, and several are in development targeting solid and hematologic malignancies including multiple myeloma. Currently, there are no reliable biomarkers of activity for these ADCs other than presence of the targeted antigen. We observed that certain cell lines are innately resistant to such ADCs, and sought to uncover the underlying mechanism of resistance.. The expression of 43 lysosomal membrane target genes was evaluated in cell lines resistant to ADCs bearing the noncleavable linker, pyrrolobenzodiazepine payload SG3376,. Loss of. Our findings support

Topics: Animals; Antineoplastic Agents, Immunological; Benzodiazepines; Biomarkers; Cell Line, Tumor; Disease Models, Animal; Gene Expression; Gene Silencing; Humans; Immunoconjugates; Maytansine; Melanoma, Experimental; Mice; Pyrroles; Xenograft Model Antitumor Assays

The clinical translation of promising products, technologies and interventions from the disciplines of nanomedicine and cell therapy has been slow and inefficient. In part, translation has been hampered by suboptimal research practices that propagate biases and hinder reproducibility. These include the publication of small and underpowered preclinical studies, suboptimal study design (in particular, biased allocation of experimental groups, experimenter bias and lack of necessary controls), the use of uncharacterized or poorly characterized materials, poor understanding of the relevant biology and mechanisms, poor use of statistics, large between-model heterogeneity, absence of replication, lack of interdisciplinarity, poor scientific training in study design and methods, a culture that does not incentivize transparency and sharing, poor or selective reporting, misaligned incentives and rewards, high costs of materials and protocols, and complexity of the developed products, technologies and interventions. In this Perspective, we discuss special manifestations of these problems in nanomedicine and in cell therapy, and describe mitigating strategies. Progress on reducing bias and enhancing reproducibility early on ought to enhance the translational potential of biomedical findings and technologies.

Topics: Ado-Trastuzumab Emtansine; Animals; Breast Neoplasms; Cell- and Tissue-Based Therapy; Disease Models, Animal; Drug Evaluation, Preclinical; Female; Male; Maytansine; Nanomedicine; Prostatic Neoplasms; Reproducibility of Results; Research Design; Tissue Extracts; Trastuzumab

Epithelial ovarian cancer (EOC) remains the most lethal gynecologic malignancy. The objective of this study was to compare the anti-tumor activity of HER2/neu-targeting monoclonal antibodies, trastuzumab (T), pertuzumab (P), combination of trastuzumab and pertuzumab (T+P) and trastuzumab-emtansine (T-DM1) in EOC with high HER2/neu expression.. Primary EOC cell lines were established and cell blocks were analyzed for HER2/neu expression. Cytostatic, apoptotic and antibody-dependent cell-mediated cytotoxicity (ADCC) activities of T, P, T+P and T-DM1 were evaluated in vitro. The in vivo antitumor activity was tested in xenograft models with 3+ HER2/neu expression.. High (3+) HER2/neu expression was detected in 40% of the primary EOC cell lines. T, P, T+P, and T-DM1 were similarly effective in inducing strong ADCC against primary EOC cell lines expressing 3+ HER2/neu. The combination of T and P was more cytostatic when compared with that of T or P used alone (p<0.0001 and p<0.0001, respectively). T-DM1 induced significantly more apoptosis when compared with T+P (p<0.0001). Finally, T-DM1 was significantly more effective in tumor growth inhibition in vivo in EOC xenografts overexpressing HER2/neu when compared to T alone, P alone and T+P (p=0.04).. In vitro and in vivo experiments with 3+ HER2/neu expressing EOC revealed limited anti-tumor activity of T or P. T-DM1 showed superior anti-tumor activity to T and P as single agents and as a combination. Our preclinical data support the design of clinical studies with T-DM1 for the treatment of chemotherapy-resistant EOC overexpressing HER2/neu.

Topics: Adult; Aged; Animals; Antibodies, Monoclonal, Humanized; Antineoplastic Combined Chemotherapy Protocols; Carcinoma; Cell Line, Tumor; Cell Proliferation; Disease Models, Animal; Drug Combinations; Female; Humans; Maytansine; Mice; Mice, SCID; Middle Aged; Ovarian Neoplasms; Receptor, ErbB-2; Trastuzumab

The development of antibody drug conjugates has provided enhanced potency to tumor-targeting antibodies by the addition of highly potent payloads. In the case of trastuzumab-DM1 (T-DM1), approved for the treatment of metastatic breast cancer, the addition of mertansine (DM1) to trastuzumab substantially increased progression-free survival. Despite these improvements, most patients eventually relapse due to complex mechanisms of resistance often associated with small molecule chemotherapeutics. Therefore, identifying payloads with different mechanisms of action (MOA) is critical for increasing the efficacy of targeted therapeutics and ultimately improving patient outcomes. To evaluate payloads with different MOA, deBouganin, a deimmunized plant toxin that inhibits protein synthesis, was conjugated to trastuzumab and compared with T-DM1 both in vitro and in vivo. The trastuzumab-deBouganin conjugate (T-deB) demonstrated greater potency in vitro against most cells lines with high levels of Her2 expression. In addition, T-deB, unlike T-DM1, was unaffected by inhibitors of multidrug resistance, Bcl-2-mediated resistance, or Her2-Her3 dimerization. Contrary to T-DM1 that showed only minimal cytotoxicity, T-deB was highly potent in vitro against tumor cells with cancer stem cell properties. Overall, the results demonstrate the potency and efficacy of deBouganin and emphasize the importance of using payloads with different MOAs. The data suggest that deBouganin could be a highly effective against tumor cell phenotypes not being addressed by current antibody drug conjugate formats and thereby provide prolonged clinical benefit.

Topics: Ado-Trastuzumab Emtansine; Animals; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Apoptosis; ATP Binding Cassette Transporter, Subfamily B; Cell Line, Tumor; Cell Survival; Disease Models, Animal; Drug Resistance, Neoplasm; Female; Gene Expression; Genes, bcl-2; Genes, erbB-2; Humans; Immunoconjugates; Maytansine; Mice; Neoplastic Stem Cells; Trastuzumab; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Elevated folate receptor alpha (FRα) expression is characteristic of epithelial ovarian cancer (EOC), thus establishing this receptor as a candidate target for the development of novel therapeutics to treat this disease. Mirvetuximab soravtansine (IMGN853) is an antibody-drug conjugate (ADC) that targets FRα for tumor-directed delivery of the maytansinoid DM4, a potent agent that induces mitotic arrest by suppressing microtubule dynamics. Here, combinations of IMGN853 with approved therapeutics were evaluated in preclinical models of EOC. Combinations of IMGN853 with carboplatin or doxorubicin resulted in synergistic antiproliferative effects in the IGROV-1 ovarian cancer cell line in vitro. IMGN853 potentiated the cytotoxic activity of carboplatin via growth arrest and augmented DNA damage; cell cycle perturbations were also observed in cells treated with the IMGN853/doxorubicin combination. These benefits translated into improved antitumor activity in patient-derived xenograft models in vivo in both the platinum-sensitive (IMGN853/carboplatin) and platinum-resistant (IMGN853/pegylated liposomal doxorubicin) settings. IMGN853 co-treatment also improved the in vivo efficacy of bevacizumab in platinum-resistant EOC models, with combination regimens causing significant regressions and complete responses in the majority of tumor-bearing mice. Histological analysis of OV-90 ovarian xenograft tumors revealed that concurrent administration of IMGN853 and bevacizumab caused rapid disruption of tumor microvasculature and extensive necrosis, underscoring the superior bioactivity profile of the combination regimen. Overall, these demonstrations of combinatorial benefit conferred by the addition of the first FRα-targeting ADC to established therapies provide a compelling framework for the potential application of IMGN853 in the treatment of patients with advanced ovarian cancer.

Topics: Animals; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Bevacizumab; Carboplatin; Cell Cycle; Cell Line, Tumor; Disease Models, Animal; Drug Resistance, Neoplasm; Drug Synergism; Female; Folate Receptor 1; Humans; Immunoconjugates; Maytansine; Mice; Neovascularization, Pathologic; Ovarian Neoplasms; Platinum; Xenograft Model Antitumor Assays

Systemic therapy for advanced bladder cancer has not changed substantially in more than 2 decades and mortality rates remain high. The recognition of HER2 over expression in bladder cancer has made HER2 a promising therapeutic target. T-DM1, a new drug consisting of the HER2 antibody trastuzumab conjugated with a cytotoxic agent, has been shown in breast cancer to be superior to trastuzumab. We tested T-DM1 in preclinical models of bladder cancer.. We evaluated the effect of T-DM1 compared to trastuzumab in different in vitro and in vivo models of HER2 over expressing bladder cancer.. RT4V6 was the highest HER2 expressing bladder cancer cell line and it showed higher growth inhibition with T-DM1 compared to trastuzumab. T-DM1 but not trastuzumab induced apoptosis of RT4V6 cells after G2/M arrest on cell cycle analysis. HER2 expression was higher in cell lines with acquired cisplatin resistance compared to the corresponding parental cell lines. Resistant cells showed higher sensitivity to T-DM1 by the induction of apoptosis. In addition, cells cultured in anchorage independent conditions increased HER2 expression compared to cells cultured in adherent conditions and T-DM1 significantly inhibited colony formation in soft agar compared to trastuzumab. In an orthotopic bladder cancer xenograft model tumor growth of cisplatin resistant RT112 was significantly inhibited by T-DM1 via the induction of apoptosis compared to treatment with control IgG or trastuzumab.. T-DM1 has promising antitumor effects in preclinical models of HER2 over expressing bladder cancer.

Topics: Ado-Trastuzumab Emtansine; Animals; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Apoptosis; Disease Models, Animal; Female; Gene Expression Regulation, Neoplastic; Humans; Male; Maytansine; Mice; Receptor, ErbB-2; Trastuzumab; Tumor Cells, Cultured; Urinary Bladder Neoplasms

The RET proto-oncogene has been implicated in breast cancer, and the studies herein describe the preclinical and safety assessment of an anti-RET antibody-drug conjugate (ADC) being developed for the treatment of breast cancer.. RET protein expression was analyzed in breast tumor samples using tissue microarrays. The fully human anti-RET antibody (Y078) was conjugated to the DM1 and DM4 derivatives of the potent cytotoxic agent maytansine using thioether and disulfide linkers, respectively. The resulting compounds, designated Y078-DM1 and Y078-DM4, were evaluated for antitumor activity using human breast cancer cell lines and established tumor xenograft models. A single-dose, 28-day, safety study of Y078-DM1 was performed in cynomolgus monkeys.. By immunohistochemistry, RET expression was detected in 57% of tumors (1,596 of 2,800 tumor sections) and was most common in HER2-positive and basal breast cancer subtypes. Potent in vitro cytotoxicity was achieved in human breast cancer cell lines that have expression levels comparable with those observed in breast cancer tissue samples. Dose-response studies in xenograft models demonstrated antitumor activity with both weekly and every-3-weeks dosing regimens. In cynomolgus monkeys, a single injection of Y078-DM1 demonstrated dose-dependent, reversible drug-mediated alterations in blood chemistry with evidence of on-target neuropathy.. RET is broadly expressed in breast cancer specimens and thus represents a potential therapeutic target; Y078-DM1 and Y078-DM4 demonstrated antitumor activity in preclinical models. Optimization of the dosing schedule or an alternate cytotoxic agent with a different mechanism of action may reduce the potential risk of neuropathy. Clin Cancer Res; 21(24); 5552-62. ©2015 AACR.

Topics: Animals; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Agents, Phytogenic; Breast Neoplasms; Bystander Effect; Cell Line, Tumor; Disease Models, Animal; Female; Gene Expression; Humans; Immunoconjugates; Immunohistochemistry; Macaca fascicularis; Maytansine; Proto-Oncogene Mas; Proto-Oncogene Proteins c-ret; Toxicity Tests; Xenograft Model Antitumor Assays

Amplification of c-erbB2 has been reported in over 30% of uterine serous carcinoma (USC) and found to confer poor survival because of high proliferation and increased resistance to therapy. In this study, we evaluated for the first time Trastuzumab emtansine (T-DM1), a novel antibody-drug conjugate, against multiple epidermal growth factor receptor-2 (HER2)-positive USC cells in vitro followed by developing a supportive in vivo model. Fifteen primary USC cell lines were assessed by immunohistochemistry (IHC) and flow cytometry for HER2 protein expression. C-erbB2 gene amplification was evaluated using fluorescent in situ hybridization. Sensitivity to T-DM1 and trastuzumab (T)-induced antibody-dependent cell-mediated cytotoxicity was evaluated in 5-h chromium release assays. T-DM1 and T cytostatic and apoptotic activities were evaluated using flow-cytometry-based proliferation assays. In vivo activity of T-DM1 versus T in USC xenografts in SCID mice was also evaluated. High levels of HER2 protein overexpression and HER2 gene amplification were detected in 33% of USC cell lines. T-DM1 was considerably more effective than trastuzumab in inhibiting cell proliferation and in causing apoptosis (P = 0.004) of USC showing HER2 overexpression. Importantly, T-DM1 was highly active at reducing tumor formation in vivo in USC xenografts overexpressing HER2 (P = 0.04) and mice treated with TDM-1 had significantly longer survival when compared to T-treated mice and control mice (P ≤ 0.0001). T-DM1 shows promising antitumor effect in HER2-positive USC cell lines and USC xenografts and its activity is significantly higher when compared to T. T-DM1 may represent a novel treatment option for HER2-positive USC patients with disease refractory to trastuzumab and traditional chemotherapy.

Topics: Ado-Trastuzumab Emtansine; Aged; Aged, 80 and over; Animals; Antibodies, Monoclonal, Humanized; Antibody-Dependent Cell Cytotoxicity; Antineoplastic Agents; Apoptosis; Carcinoma; Cell Cycle Checkpoints; Cell Proliferation; Disease Models, Animal; Female; Gene Amplification; Gene Expression; Gene Expression Regulation, Neoplastic; Humans; Immunohistochemistry; In Situ Hybridization, Fluorescence; Maytansine; Middle Aged; Receptor, ErbB-2; RNA, Messenger; Trastuzumab; Uterine Neoplasms; Xenograft Model Antitumor Assays

The receptor tyrosine kinase RON is critical in epithelial tumorigenesis and a drug target for cancer therapy. Here, we report the development and therapeutic efficacy of a novel anti-RON antibody Zt/g4-maytansinoid (DM1) conjugates for targeted colorectal cancer (CRC) therapy.. Zt/g4 (IgG1a/κ) was conjugated to DM1 via thioether linkage to form Zt/g4-DM1 with a drug-antibody ratio of 4:1. CRC cell lines expressing different levels of RON were tested in vitro to determine Zt/g4-DM1-induced RON endocytosis, cell-cycle arrest, and cytotoxicity. Efficacy of Zt/g4-DM1 in vivo was evaluated in mouse xenograft CRC tumor model.. Zt/g4-DM1 rapidly induced RON endocytosis, arrested cell cycle at G2-M phase, reduced cell viability, and caused massive cell death within 72 hours. In mouse xenograft CRC models, Zt/g4-DM1 at a single dose of 20 mg/kg body weight effectively delayed CRC cell-mediated tumor growth up to 20 days. In a multiple dose-ranging study with a five injection regimen, Zt/g4-DM1 inhibited more than 90% tumor growth at doses of 7, 10, and 15 mg/kg body weight. The minimal dose achieving 50% of tumor inhibition was approximately 5.0 mg/kg. The prepared Zt/g4-DM1 is stable at 37°C for up to 30 days. At 60 mg/kg, Zt/g4-DM1 had a moderate toxicity in vivo with an average of 12% reduction in mouse body weight.. Zt/g4-DM1 is highly effective in targeted inhibition of CRC cell-derived tumor growth in mouse xenograft models. This work provides the basis for development of humanized Zt/g4-DM1 for RON-targeted CRC therapy in the future.

Topics: Animals; Antibodies, Monoclonal; Cell Cycle; Cell Death; Cell Line, Tumor; Cell Proliferation; Colorectal Neoplasms; Disease Models, Animal; Endocytosis; Female; Humans; Maytansine; Mice; Protein Binding; Receptor Protein-Tyrosine Kinases; Tumor Burden; Xenograft Model Antitumor Assays

Human epidermal growth factor receptor 2 (HER2)-targeted therapy by trastuzumab has become increasingly important for treating HER2-positive cancers, and trastuzumab emtansine (T-DM1) is expected to serve as an effective alternative to trastuzumab. Pertuzumab, a HER2 dimerization inhibitor, showed prolonged progression-free survival when used with trastuzumab for HER2-positive breast cancer. In this study, we investigated the effect of combining T-DM1 and pertuzumab on xenografted gastric tumors. T-DM1 as a single agent showed significant antitumor activity in all the three HER2-high expression tumor models tested (NCI-N87, SCH and 4-1ST) but was ineffective against two HER2-low expression tumors (SNU-16 and MKN-28). Using the T-DM1-sensitive NCI-N87 model, the combination efficacy of T-DM1 and pertuzumab was elucidated. The combination induced significant tumor regression, whereas T-DM1 or pertuzumab alone did not. In cultured NCI-N87 cells stimulated with epidermal growth factor (EGF) or heregulin-α, concomitant treatment of T-DM1 and pertuzumab significantly inhibited proliferation and increased caspase 3/7 activity compared to either agent alone. Only the combination significantly inhibited the phosphorylation of EGFR or HER3, and its downstream factor AKT. Suppressed HER3 phosphorylation by the combination was also seen in the NCI-N87 xenografted tumors. Compared to single agent treatments, the combination treatment significantly enhanced antibody-dependent cellular cytotoxicity (ADCC) against NCI-N87 cells. These findings suggest that T-DM1 in combination with pertuzumab shows significant antitumor activity by increasing AKT signal inhibition and ADCC in HER2-positive gastric cancers.

Topics: Ado-Trastuzumab Emtansine; Animals; Antibodies, Monoclonal, Humanized; Antibody-Dependent Cell Cytotoxicity; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Blotting, Western; Cell Proliferation; Disease Models, Animal; Drug Synergism; ErbB Receptors; Flow Cytometry; Humans; Immunoenzyme Techniques; In Situ Hybridization, Fluorescence; Male; Maytansine; Mice; Mice, Inbred BALB C; Phosphorylation; Receptor, ErbB-2; Signal Transduction; Stomach Neoplasms; Trastuzumab; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

The use of a tumor colony assay was evaluated for its ability to predict anticancer drug response in an N[4-(5-nitro-2-furyl)-2-thiazolyl] formamide mouse bladder tumor model. One-hour and continuous drug exposure were compared to determine what effect altering drug concentration and time of exposure would have on the predictability of the tumor colony assay in the murine model. Ten anticancer drugs were tested in the murine model, and tumor cells removed from control mice were used for in vitro drug testing. One-hour and continuous drug exposure (using the one-hour drug level) were performed simultaneously and the in vitro and in vivo data compared. Using one-hour drug incubation in the tumor colony assay resulted in a true positive predictive rate of 54 per cent and a true negative predictive rate of 70 per cent. Continuous drug incubation overestimated drug sensitivity resulting in a drop in the predictability of the tumor colony assay. We conclude that using one-hour drug exposure the tumor colony assay is predictive of chemotherapeutic drug response in this murine bladder tumor model.

Topics: Animals; Antineoplastic Agents; Bleomycin; Cell Line; Cisplatin; Colony-Forming Units Assay; Disease Models, Animal; Doxorubicin; FANFT; Female; Fluorouracil; Maytansine; Methotrexate; Mice; Mice, Inbred C3H; Mitomycin; Mitomycins; Podophyllotoxin; Streptozocin; Time Factors; Trichothecenes; Tumor Stem Cell Assay; Urinary Bladder Neoplasms