Multi-Chemotherapeutic Schedules Containing the pan-FGFR Inhibitor ARQ 087 are Safe and Show Antitumor Activity in Different Xenograft Models

ARQ 087 is a multi-tyrosine kinase inhibitor with potent activity against the FGFR receptor family, currently in Phase I clinical studies for the treatment of advanced solid tumors. The compound has a very safe profile and induces tumor regressions in FGFR-driven models. The feasibility of combining ARQ 087 with chemotherapy was investigated in FGFR deregulated human xenografts. Nude mice were transplanted subcutaneously with H1581, and when tumor masses reached 150 mg, were randomized to receive vehicle, ARQ 087, paclitaxel, carboplatin as single agents or in combination. Similar experimental conditions were applied in nude mice bearing SNU16 and MFE296 xenografts, with the inclusion of capecitabine in the former xenograft model. In the different xenograft models, the drugs given as single agents ranged from very active to partially active. The double combinations were more active than the single ones, but the triple combinations were the most active. In particular, the combination of ARQ 087 + paclitaxel + carboplatin in H1581 bearing mice was able to induce tumor regression in all the mice, with 6/8 mice tumor free at day 140 after tumor transplant. Of note, no toxic deaths nor premature stopping or delaying of drug administration were observed. The data herein reported demonstrated the feasibility of using xenografts models for poli-chemotherapeutic trials mimicking the best standard of care in treatment of specific tumor type and that ARQ 087, a new pan-FGFR inhibitor, can be safely combined with standard cytotoxic chemotherapeutic drugs with apparently no sign of cumulative toxicity and an associated increased antitumor effect.     

Targeting Trop-2 in cancer: Recent research progress and clinical application

The development of new antitumor drugs depends mainly upon targeting tumor cells precisely. Trophoblast surface antigen 2 (Trop-2) is a type I transmembrane glycoprotein involved in Ca²⁺ signaling in tumor cells. It is highly expressed in various tumor tissues than in normal tissues and represents a novel and promising molecular target for caner targeted therapy. Up to now, the mechanisms and functions associated with Trop-2 have been extensively studied in a variety of solid tumors. According to these findings, Trop-2 plays an important role in cell proliferation, apoptosis, cell adhesion, epithelial-mesenchymal transition, as well as tumorigenesis and tumor progression. In addition, Trop-2 related drugs are also being developed widely. There are a number of Trop-2 related ADC drugs that have demonstrated potent antitumor activity and are currently been studied, such as Sacituzumab Govitecan (SG) and Datopotamab Deruxtecan (Dato-Dxd). In this study, we reviewed the progress of Trop-2 research in solid tumors. We also sorted out the composition and rationale of Trop-2 related drugs and summarized the related clinical trials. Finally, we discussed the current status of Trop-2 research and expanded our perspectives on its future research directions. Importantly, we found that Trop-2 targeted ADCs have great potential for combination with other antitumor therapies. Trop-2 targeted ADCs can reprogramme tumor microenvironment through multiple signaling pathways, ultimately activating antitumor immunity.     

Combination treatment with MEK and AKT inhibitors is more effective than each drug alone in human non-small cell lung cancer in vitro and in vivo

AZD6244 and MK2206 are targeted small-molecule drugs that inhibit MEK and AKT respectively. The efficacy of this combination in lung cancer is unknown. Our previous work showed the importance of activated AKT in mediating resistance of non-small cell lung cancer (NSCLC) to AZD6244. Thus we hypothesized that dual inhibition of both downstream MEK and AKT pathways would induce synergistic antitumor activity. In this study, we evaluated the efficacy of AZD6244 and MK2206 individually on a large panel of lung cancer cell lines. Then, we treated 28 human lung cancer cell lines with a combination of AZD6244 and MK2206 at clinically applicable drug molar ratios. The AZD6244-MK2206 combination therapy resulted in a synergistic effect on inhibition of lung cancer cell growth compared to the results of single drug treatment alone. MK2206 enhanced AZD6244-induced Bim overexpression and apoptosis in A549 and H157 cells. When we tested the combination of AZD6244 and MK2206 at ratios of 8∶1, 4∶1, 2∶1, and 1∶8, we found that the synergistic effect of the combination therapy was ratio-dependent. At ratios of 8∶1, 4∶1, and 2∶1, the drug combination consistently demonstrated synergy, whereas decreasing the ratio to 1∶8 resulted in a loss of synergy and produced an additive or antagonistic effect in most cell lines. Furthermore, the AZD6244-MK2206 combination therapy showed synergy in the suppression of A549 and H157 xenograft tumor growth and increased mean animal survival time. The AZD6244-MK2206 combination therapy resulted in effective inhibition of both p-ERK and p-AKT expression in tumor tissue. In addition, a significant increase of apoptosis was detected in tumor tissue from mice treated with AZD6244-MK2206 compared with that from the single agent treated mice. Our study suggests that the combination of AZD6244 and MK2206 has a significant synergistic effect on tumor growth in vitro and in vivo and leads to increased survival rates in mice bearing highly aggressive human lung tumors.     

Synthesis and biological activity of stable and potent antitumor agents, aniline nitrogen mustards linked to 9-anilinoacridines via a urea linkage

To improve the chemical stability and therapeutic efficacy of N-mustard, a series of phenyl N-mustard linked to DNA-affinic 9-anilinoacridines and acridine via a urea linker were synthesized and evaluated for antitumor studies. The new N-mustard derivatives were prepared by the reaction of 4-bis(2-chloroethyl)aminophenyl isocyanate with a variety of 9-anilinoacridines or 9-aminoacridine. The antitumor studies revealed that these agents exhibited potent cytotoxicity in vitro without cross-resistance to taxol or vinblastine and showed potent antitumor therapeutic efficacy in nude mice against human tumor xenografts. It also showed that 24d was capable of inducing marked dose-dependent levels of DNA cross-linking by comet assay and has long half-life in rat plasma.     

Successful colon cancer eradication after chemoimmunotherapy is associated with profound phenotypic change of intratumoral myeloid cells

IL-12 is a potent immunostimulatory cytokine, but its impact as an antitumor drug in clinical practice is limited. Upsurge of regulatory T cells (Treg) in the tumor milieu has been proposed to limit the efficacy of the treatment. In this paper, two drugs (cyclophosphamide [CPA] and anti-CD25 mAb) widely used to eliminate Treg were used in an attempt to enhance the antitumor effect of IL-12 gene therapy. Both anti-CD25 and CPA combined with IL-12 were able to deplete intratumoral Treg and myeloid-derived suppressor cells (MDSC), but only IL-12 plus CPA achieved significant antitumor activity in mice with large established s.c. colon carcinoma. This therapeutic effect was associated with the emergence of a heterogeneous population of myeloid cells within the tumor, termed inflammatory myeloid cells (IMC), composed of Ly6C(high)Ly6G(low) inflammatory monocytes and Ly6G(high)Ly6C(+) neutrophils. IMC showed a distinctive pattern of cytokine/chemokine production, and in contrast to MDSC, they did not induce conversion of naive CD4(+) T cells into Treg. The appearance of IMC coincided with intense tumor infiltration by effector T cells, which was abrogated by elimination of IMC by anti-Gr1 mAb, a maneuver that abolished the antitumor effect of the therapy. Therefore, the combination of IL-12 and CPA eliminates intratumoral Treg and MDSC, while it induces the appearance of IMC within the tumor microenvironment. The latter effect is essential to facilitate effector T cell infiltration and subsequent tumor elimination.     

Improved yield and stability of L49-sFv-beta-lactamase, a single-chain antibody fusion protein for anticancer prodrug activation, by protein engineering

The L49 single-chain Fv fused to beta-lactamase (L49-sFv-bL) combined with the prodrug C-Mel is an effective anticancer agent against tumor cells expressing the p97 antigen. However, large-scale production of L49-sFv-bL from refolded E. coli inclusion bodies has been problematic due to inefficient refolding and instability of the fusion protein. Sequence analysis of the L49-sFv framework regions revealed three residues in the framework regions at positions L2, H82B, and H91, which are not conserved for their position, occurring in <1% of sequences in Fv sequence databases. One further unusual residue, found in <3% of variable sequences, was observed at position H39. Each unusual residue was mutated to a conserved residue for its position and tested for refolding yield from inclusion bodies following expression in E. coli. The three V(H) single mutants showed improvement in the yield of active protein and were combined to form double and triple mutants resulting in a 7-8-fold increased yield compared to the parental protein. In an attempt to further improve yield, the orientation of the triple mutant was reversed to create a bL-L49-sFv fusion protein resulting in a 3-fold increase in expressed inclusion body protein and producing a 20-fold increase in the yield of purified protein compared to the parental protein. The triple mutants in both orientations displayed increased stability in murine plasma and binding affinity was not affected by the introduced mutations. Both triple mutants also displayed potent in vitro cytotoxicity and in vivo antitumor activity against p97 expressing melanoma cells and tumor xenografts, respectively. These results show that a rational protein-engineering approach improved the yield, stability, and refolding characteristics of L49-sFv-bL while maintaining binding affinity and therapeutic efficacy.     

PDTX模型的研究进展

细胞源性异种移植(cell line-derived xenografts,CDX)与原发肿瘤相比失去了肿瘤的异质性和基因的多样性,在临床前的实验中不能有效评估肿瘤药物的疗效和安全性,致使临床药物高消耗而没有达到治疗疾病的目的,严重阻碍了临床药物的发展;人源性肿瘤组织异种移植(patient-derived tumor xenografts,PDTX)保持了原发肿瘤的分子学、基因学和病理学特征,而且经过在小鼠体内传代它仍保持了原发肿瘤的这些特性,为肿瘤的个体化治疗提供了更好的模型。PDTX模型的这些特性与CDX模型相比在肿瘤的个体化治疗方面更具有指导意义。本文将就PDTX模型的特征及其在肿瘤研究领域中的应用作系统阐述。     

Intravenous injection of the oncolytic virus M1 awakens antitumor T cells and overcomes resistance to checkpoint blockade

Reversing the highly immunosuppressive tumor microenvironment (TME) is essential to achieve long-term efficacy with cancer immunotherapy. Despite the impressive clinical response to checkpoint blockade in multiple types of cancer, only a minority of patients benefit from this approach. Here, we report that the oncolytic virus M1 induces immunogenic tumor cell death and subsequently restores the ability of dendritic cells to prime antitumor T cells. Intravenous injection of M1 disrupts immune tolerance in the privileged TME, reprogramming immune-silent (cold) tumors into immune-inflamed (hot) tumors. M1 elicits potent CD8⁺ T cell-dependent therapeutic effects and establishes long-term antitumor immune memory in poorly immunogenic tumor models. Pretreatment with M1 sensitizes refractory tumors to subsequent checkpoint blockade by boosting T-cell recruitment and upregulating the expression of PD-L1. These findings reveal the antitumor immunological mechanism of the M1 virus and indicated that oncolytic viruses are ideal cotreatments for checkpoint blockade immunotherapy.Subject terms: Cancer microenvironment, Targeted therapies     

Oncolytic Immunotherapy: Can’t Start a Fire Without a Spark

Recent advances in cancer immunotherapy have renewed interest in oncolytic viruses (OVs) as a synergistic platform for the development of novel antitumor strategies. Cancer cells adopt multiple mechanisms to evade and suppress antitumor immune responses, essentially establishing a non-immunogenic (‘cold’) tumor microenvironment (TME), with poor T-cell infiltration and low mutational burden. Limitations to the efficacy of immunotherapy still exist, especially for a variety of solid tumors, where new approaches are necessary to overcome physical barriers in the TME and to mitigate adverse effects associated with current immunotherapeutics. OVs offer an attractive alternative by inducing direct oncolysis, immunogenic cell death, and immune stimulation. These multimodal mechanisms make OVs well suited to reprogram non-immunogenic tumors and TME into inflamed, immunogenic (‘hot’) tumors; enhanced release of tumor antigens by dying cancer cells is expected to augment T-cell infiltration, thereby eliciting potent antitumor immunity. Advances in virus engineering and understanding of tumor biology have allowed the optimization of OV-tumor selectivity, oncolytic potency, and immune stimulation. However, OV antitumor activity is likely to achieve its greatest potential as part of combinatorial strategies with other immune or cancer therapeutics.     

G3139 and other CpG-containing immunostimulatory phosphorothioate oligodeoxynucleotides are potent suppressors of the growth of human tumor xenografts in nude mice

Several phosphorothioate antisense oligodeoxynucleotides (ODN) are developed to target factors potentially involved in tumor growth and apoptosis suppression. Among them, the 18-mer G3139 (Oblimersen), which targets Bcl-2, is currently being tested in phase II and phase III clinical trials for various tumors in combination with chemotherapy. On the other hand, ODNs containing CpG dinucleotides (CpG-ODN) within specific-sequence contexts (CpG motifs) have been shown to activate rodent or primate immune cells via toll-like receptor 9 (TLR9) and have demonstrated remarkable T cell-dependent antitumor efficacy in a series of murine tumor models. However, immune cell activation by CpG-ODN is largely diminished upon C-5 methylation at CpG cytosine. As G3139 contains CpG motifs, we questioned whether the antitumor effects seen in human tumor xenografts might be abrogated by cytosine C-5 methylation of G3139, which retained the ability of G3139 to suppress Bcl-2 expression in tissue culture, or by similar derivatization of other phosphorothioate ODNs developed for the immune activation of rodent or human cells. The in vivo antitumor efficacy of the immunostimulatory H1826 and H2006 ODNs was compared with that of G3139. Bcl-2 suppression achieved by G3139 purportedly sensitizes tumor cells toward cytotoxic agents, and some of the experiments employed combinations of ODN with such drugs as cisplatin or etoposide. H1826, H2006, and G3139 all produced similar, striking, growth inhibitory effects on either H69 SCLC, A2780 ovarian carcinoma, or A549 lung adenocarcinoma human tumor xenografts at doses of 0.3 mg/kg and 1 mg/kg (H1826, H2006) or 12 mg/kg (G3139) per day. In contrast, the H2006-mC (1 mg/kg) or G3139-mC (12 mg/kg) derivatives demonstrated no significant antitumor effects. The combination of G3139 (12 mg/kg) with cisplatin produced some additive antitumor efficacy, which was not seen in combinations of G3139-mC (12 mg/kg) or H1826 (1 mg/kg) with cisplatin. G3139, at a dose of 12 mg/kg, alone induced extensive enlargement of the spleen. Immunostimulation was evaluated in vitro by flow cytometric measurements of the CD80 and CD86 activation markers found on CD19+ murine splenocytes. The CpG-ODN producing strong antitumor effects in vivo also induced these activation markers in vitro, in contrast to the in vivo inactive G3139-mC. Our data indicate a significant contribution of the immunostimulatory properties of CpG-ODN (including G3139) to the antitumor effects observed in nude mouse xenograft models. This is in contrast to previous data presented by other authors indicating that the activity of G3139 in human tumor xenografts was Bcl-2 specific. Furthermore, as nude mice are devoid of T cells, a T cell-mediated immune response apparently is not required for the potent antitumor responses observed here; innate immune responses are sufficient.     

Bacterially-Derived Nanocells for Tumor-Targeted Delivery of Chemotherapeutics and Cell Cycle Inhibitors

Chemotherapeutic drug therapy in cancer is seriously hampered by severe toxicity primarily due to indiscriminate drug distribution and consequent collateral damage to normal cells. Molecularly targeted drugs such as cell cycle inhibitors are being developed to achieve a higher degree of tumor cell specificity and reduce toxic side effects. Unfortunately, relative to the cytotoxics, many of the molecularly targeted drugs are less potent and the target protein is expressed only at certain stages of the cell cycle thus necessitating regimens like continuous infusion therapy to arrest a significant number of tumor cells in a heterogeneous tumor mass. Here we discuss targeted drug delivery nanovectors and a recently reported bacterially-derived 400nm sized minicell that can be packaged with therapeutically significant concentrations of chemotherapeutic drugs, targeted to tumor cell surface receptors and effect intracellular drug delivery with highly significant anti-tumor effects in-vivo. We also report that molecularly targeted drugs can also be packaged in minicells and targeted to tumor cells with highly significant tumor growth-inhibition and regression in mouse xenografts despite administration of minute amounts of drug. This targeted intracellular drug delivery may overcome many of the hurdles associated with the delivery of cytotoxic and molecularly targeted drugs.     

β-elemene combined with temozolomide in treatment of brain glioma

Temozolomide (TMZ) is a widely used chemotherapeutic agent for malignant glioma. β-Elemene has been reported to have the ability of passing through the blood-brain barrier and reverse multidrug resistance. In the present study, transport of drugs through the in vitro blood-brain barrier (BBB) model also suggested that β-elemene can assist in TMZ transport to the brain. Plasma and brain pharmacokinetics demonstrated that when β-elemene is used in combination with TMZ, the metabolic rate of TMZ in plasma is slowed, and mean residence time (MRT) in brain is prolonged. The brain tissue distribution at 1 h indicated that the combination of TMZ and β-elemene promotes the distribution of β-elemene in the brain but slightly reduces the distribution of TMZ in the brain. Furthermore the antitumor effect and toxicity in vivo were also investigated. The combination of β-elemene and TMZ was well tolerated and significantly inhibited tumor growth in glioma xenografts. In summary, the present study indicates a synergistic antitumor effect of β-elemene and TMZ in glioma.     

The proteasome inhibitor bortezomib enhances ATRA-induced differentiation of neuroblastoma cells via the JNK mitogen-activated protein kinase pathway

Neuroblastoma (NB) is the most common extracranial solid tumor in childhood. Differentiated human NBs are associated with better outcome and lower stage; induction of differentiation is considered to be therapeutically advantageous. All-trans retinoic acid (ATRA) has been shown to induce the differentiation of neuroblastoma (NB) cell lines. The proteasome inhibitor bortezomib inhibits cell growth and angiogenesis in NBs. Here, we investigated the synergistic effect between bortezomib and ATRA in inducing NB cell differentiation in different NB cell lines. Bortezomib combined with ATRA had a significantly enhanced antiproliferative effect. This inhibition was characterized by a synergistic increase in neuronal differentiation. At the same time, the combination therapy showed little neuronal toxicity which was assessed in primary cultures of rat cerebellar granule cells by the MTT assay, PI staining. The combination of bortezomib and ATRA triggered increased differentiation through the activation of proteins, including RARα, RARβ, RARγ, p-JNK and p21, compared with ATRA treatment alone. Using JNK inhibitor SP600125 to block JNK-dependent activity, the combination therapy-induced neuronal differentiation was partially attenuated. In addition, p21 shRNA had no effect on the combination therapy-induced neuronal differentiation. The in vivo antitumor activities were examined in human NB cell xenografts and GFP-labeled human NB cell xenografts. Treatment of human NB cell CHP126-bearing nude mice with ATRA plus bortezomib resulted in more significant tumor growth inhibition than mice treated with either drug alone. These findings provide the rationale for the development of a new therapeutic strategy for NB based on the pharmacological combination of ATRA and bortezomib.     

Potential drugs used in the antibody–drug conjugate (ADC) architecture for cancer therapy

Cytotoxic small-molecule drugs have a major influence on the fate of antibody–drug conjugates (ADCs). An ideal cytotoxic agent should be highly potent, remain stable while linked to ADCs, kill the targeted tumor cell upon internalization and release from the ADCs, and maintain its activity in multidrug-resistant tumor cells. Lessons learned from successful and failed experiences in ADC development resulted in remarkable progress in the discovery and development of novel highly potent small molecules. A better understanding of such small-molecule drugs is important for development of effective ADCs. The present review discusses requirements making a payload appropriate for antitumor ADCs and focuses on the main characteristics of commonly-used cytotoxic payloads that showed acceptable results in clinical trials. In addition, the present study represents emerging trends and recent advances of payloads used in ADCs currently under clinical trials.     

Targeting LSD1 suppresses stem cell-like properties and sensitizes head and neck squamous cell carcinoma to PD-1 blockade

Head and neck squamous cell carcinoma (HNSCC) is a highly aggressive tumor with poor clinical outcomes due to recurrence, metastasis, and treatment resistance. Cancer stem cells (CSCs), a small population among tumor cells, are proposed to be responsible for tumor initiation, progression, metastasis, drug resistance, and recurrence. Here we show that high LSD1 expression was a predictor of poor prognosis for HNSCC patients. We found that high expression of LSD1 is essential for the maintenance of the CSC properties by regulating Bmi-1 expression. Moreover, tumor LSD1 ablation suppresses CSC-like characteristics in vitro and inhibits tumorigenicity in vivo in immune-deficient xenografts. However, this deletion induces the upregulation of PDL1 levels, which compromises antitumor immunity and reduces antitumor efficacy in an immune-competent mouse model. Functionally, the combination of LSD1 inhibitor and anti-PD-1 monoclonal antibody can overcome tumor immune evasion and greatly inhibit tumor growth, which was associated with reduced Ki-67 level and augmented CD8⁺ T cell infiltration in immunocompetent tumor-bearing mouse models. In summary, these findings provide a novel and promising combined strategy for the treatment of HNSCC using a combination of LSD1 inhibition and PD-1 blockade.Subject terms: Oral cancer, Stem-cell research     

Ex Vivo Treatment Response of Primary Tumors and/or Associated Metastases for Preclinical and Clinical Development of Therapeutics

The molecular analysis of established cancer cell lines has been the mainstay of cancer research for the past several decades. Cell culture provides both direct and rapid analysis of therapeutic sensitivity and resistance. However, recent evidence suggests that therapeutic response is not exclusive to the inherent molecular composition of cancer cells but rather is greatly influenced by the tumor cell microenvironment, a feature that cannot be recapitulated by traditional culturing methods. Even implementation of tumor xenografts, though providing a wealth of information on drug delivery/efficacy, cannot capture the tumor cell/microenvironment crosstalk (i.e., soluble factors) that occurs within human tumors and greatly impacts tumor response. To this extent, we have developed an ex vivo (fresh tissue sectioning) technique which allows for the direct assessment of treatment response for preclinical and clinical therapeutics development. This technique maintains tissue integrity and cellular architecture within the tumor cell/microenvironment context throughout treatment response providing a more precise means to assess drug efficacy.     

Blockade of programmed death-1 pathway rescues the effector function of tumor-infiltrating T cells and enhances the antitumor efficacy of lentivector immunization

Despite intensive effort, the antitumor efficacy of tumor vaccines remains limited in treating established tumors regardless of the potent systemic tumor-specific immune response and the increases of tumor infiltration of T effector cells. In the current study, we demonstrated that although lentivector (lv) immunization markedly increased Ag-dependent tumor infiltration of CD8 and CD4 T cells and generated Ag-specific antitumor effect, it simultaneously increased the absolute number of myeloid-derived suppressor cells and regulatory T cells in the tumor lesions. In addition, lv immunization induced expression of programmed death-ligand 1 in the tumor lesions. Furthermore, the tumor-infiltrating CD8 T cells expressed high levels of programmed death-1 and were partially dysfunctional, producing lower amounts of effector cytokines and possessing a reduced cytotoxicity. Together, these immune-suppression mechanisms in the tumor microenvironment pose a major obstacle to effective tumor immunotherapy and may explain the limited antitumor efficacy of lv immunization. The loss of effector function in the tumor microenvironment is reversible, and the effector function of CD8 T cells in the tumor could be partially rescued by blocking programmed death-1 and programmed death-ligand 1 pathway in vitro and in vivo, resulting in enhanced antitumor efficacy of lv immunization. These data suggest that immunization alone may exacerbate immune suppression in the tumor lesions and that methods to improve the tumor microenvironment and to rescue the effector functions of tumor-infiltrating T cells should be incorporated into immunization strategies to achieve enhanced antitumor efficacy.     

Potent antitumor activities of recombinant human PDCD5 protein in combination with chemotherapy drugs in K562 cells

Conventional chemotherapy is still frequently used. Programmed cell death 5 (PDCD5) enhances apoptosis of various tumor cells triggered by certain stimuli and is lowly expressed in leukemic cells from chronic myelogenous leukemia patients. Here, we describe for the first time that recombinant human PDCD5 protein (rhPDCD5) in combination with chemotherapy drugs has potent antitumor effects on chronic myelogenous leukemia K562 cells in vitro and in vivo. The antitumor efficacy of rhPDCD5 protein with chemotherapy drugs, idarubicin (IDR) or cytarabine (Ara-C), was examined in K562 cells in vitro and K562 xenograft tumor models in vivo. rhPDCD5 protein markedly increased the apoptosis rates and decreased the colony-forming capability of K562 cells after the combined treatment with IDR or Ara-C. rhPDCD5 protein by intraperitoneal administration dramatically improved the antitumor effects of IDR treatment in the K562 xenograft model. The tumor sizes and cell proliferation were significantly decreased; and TUNEL positive cells were significantly increased in the combined group with rhPDCD5 protein and IDR treatment compared with single IDR treatment groups. rhPDCD5 protein, in combination with IDR, has potent antitumor effects on chronic myelogenous leukemia K562 cells and may be a novel and promising agent for the treatment of chronic myelogenous leukemia.     

Dichloroacetate (DCA) enhances tumor cell death in combination with oncolytic adenovirus armed with MDA-7/IL-24

Dichloroacetate (DCA) is a metabolic modulator for the treatment of lactic acidosis and inherited mitochondrial diseases. A recent study showed that DCA treatment could induce apoptosis in many kinds of tumor cell lines via mitochondrial apoptotic pathway while sparing normal cells. ONYX-015 (dl 1520) is one of the oncolytic adenoviruses developed by the deletion of E1B-55kD gene of type 5 adenoviral DNA, and it replicates efficiently and selectively in tumor cells. ZD55-IL-24, an E1B-55kD deleted oncolytic adenovirus carrying interleukin-24 (IL-24, also called melanoma differentiation associated gene-7), had showed potent antitumor efficacy in a variety of tumor cells and exerted no apparent toxicity on normal cells. Given both the good therapeutic effect and low toxicity of these agents, here we investigated whether DCA in combination with ZD55-IL-24 or ONYX-015 could have more efficient antitumor activity in vitro experiments. Therefore, we tested the cytotoxicity of combination therapy in normal hepatic cells L-02 and QSG-7701 using the MTT assay. Our results showed that DCA combined with ONYX-015 or ZD55-IL-24 exhibited more potent antitumor activity than DCA or virus alone, and the combination treatment did not have superimposed toxicities in normal cells. Thus, a novel combination therapy associating oncolytic adenoviruses with relatively low toxic drug without severe side effects was proposed.     

The improved effects of specific active immunotherapy on a rat fibrosarcoma by antitumor drugs

Summary We have tried to find out if the combination of a xenogenized tumor cell vaccine and antitumor drugs is able to induce a synergistic increase in the antitumor therapeutic effect. The degree of increase in the LTD₅₀ (50% lethal tumor dose) is expressed numerically, as a quantitative index designed to compare degrees of transplantation resistance to tumor cell challenge. A LTD₅₀ was achieved by an intradermal (i. d.) immunization with xenogenized tumor cells when challenged with tumor cells implanted intraperitoneally 2 weeks after the immunization: this LTD₅₀ value was 527 000 times higher than that of the non-immunized group. When we combined this type of immunization with appropriate doses of bleomycin (BLM) or cyclophosphamide (CY), which are able to augment antitumor immunity, the LTD₅₀ was 723 000–1190 000 times higher than that of the non-immunized group. This increase in the LTD₅₀ is definitely higher than that achieved by a single immunization with irradiated tumor cells (× 33 000) and combined with either BLM (× 93 000) or CY (×140 000). We also studied the therapeutic effect of a tumor cell vaccine combined with antitumor drugs BLM or CY in tumor-bearing rats. We observed a synergistic effect caused by BLM or CY after i. d. immunization with xenogenized tumor cells: this showed a significant increase when compared with the therapeutic effects obtained by chemotherapy alone (P <0.01). Nevertheless, there was no evidence that the above antitumor effects is superior to the effect achieved by irradiated tumor cells.