Improvement of antitumor therapies based on vaccines and immune-checkpoint inhibitors by counteracting tumor-immunostimulationw

Immune-checkpoint inhibitors and antitumor vaccines may produce both tumor-inhibitory and tumor-stimulatory effects on growing tumors depending on the stage of tumor growth at which treatment is initiated. These paradoxical results are not necessarily incompatible with current tumor immunology but they might better be explained assuming the involvement of the phenomenon of tumor immunostimulation. This phenomenon was originally postulated on the basis that the immune response (IR) evoked in Winn tests by strong chemical murine tumors was not linear but biphasic, with strong IR producing inhibition and weak IR inducing stimulation of tumor growth. Herein, we extended those former observations to weak spontaneous murine tumors growing in pre-immunized, immune-competent and immune-depressed mice. Furthermore, we demonstrated that the interaction of specifical T cells and target tumor cells at low stimulatory ratios enhanced the production of chemokines aimed to recruit macrophages at the tumor site, which, upon activation of toll-like receptor 4 and p38 signaling pathways, would recruit and activate more macrophages and other inflammatory cells which would produce growth-stimulating signals leading to an accelerated tumor growth. On this basis, the paradoxical effects achieved by immunological therapies on growing tumors could be explained depending upon where the therapy-induced IR stands on the biphasic IR curve at each stage of tumor growth. At stages where tumor growth was enhanced (medium and large-sized tumors), counteraction of the tumor-immunostimulatory effect with anti-inflammatory strategies or, more efficiently, with selective inhibitors of p38 signaling pathways enabled the otherwise tumor-promoting immunological strategies to produce significant inhibition of tumor growth.Fil: Chiarella, Paula. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Vermeulen, Mónica. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Montagna, Daniela R.. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Vallecorsa, Pablo. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Strazza, Ariel Ramiro. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Meiss, Roberto P.. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Bustuoabad, Oscar D.. Retired; ArgentinaFil: Ruggiero, Raúl A.. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Prehn, Richmond T.. University Of Washington, Seattle

Evaluation of α2-Integrin Expression as a Biomarker for Tumor Growth Inhibition for the Investigational Integrin Inhibitor E7820 in Preclinical and Clinical Studies

E7820 is an orally active inhibitor of α2-integrin mRNA expression, currently tested in phases I and II. We aimed to evaluate what levels of inhibition of integrin expression are needed to achieve tumor stasis in mice, and to compare this to the level of inhibition achieved in humans. Tumor growth inhibition was measured in mice bearing a pancreatic KP-1 tumor, dosed at 12.5–200 mg/kg over 21 days. In the phase I study, E7820 was administered daily for 28 days over a range of 0–200 mg, followed by a 7-day washout period. PK-PD models were developed in NONMEM. α2-Integrin expression measured on platelets, corresponding to tumor stasis at t = 21 in 50% and 90% of the mice (Iint,50, Iint,90) were calculated. It was evaluated if these levels of inhibition could be achieved in patients at tolerable doses. One hundred nineteen α2-Integrin measurements and 210 tumor size measurements were available from mice. The relationship between PK and α2-integrin expression was modeled using an indirect-effect model, subsequently linked to an exponential tumor growth model. Iinh,50 and Iinh,90 were 14.7% (RSE 7%) and 17.9% (RSE 8%). Four hundred sixty two α2-integrin measurements were available from 29 patients. Using the schedule of 100 mg qd (MTD), α2-integrin expression was inhibited more strongly than the Iint,50 and Iint,90 in greater than 95% and greater than 50% of patients, respectively. Moderate inhibition of α2-integrin expression corresponded to tumor stasis in mice, and similar levels could be reached in patients with the dose level of 100 mg qd

In vivo manipulation of interleukin-2 expression by a retroviral tetracycline (tet)-regulated system

We have used the tetracycline (tet)-regulated system as described previously to evaluate the applicability of controlled gene expression in cancer gene therapy. As a model gene, we used the human interleukin-2 (IL-2) gene, which has been placed under the transcriptional control of the tetO/promoter. Human melanoma cells were transduced by two modified retroviral tet vectors containing the transactivator regulatory unit and the IL-2 gene driven by the tetO/promoter, respectively. In the absence of tet, IL-2 expression in the target cells was stable over several months. IL-2 production was in the range of 40 U/106 cells/24 hours. A fine tuning of IL-2 expression could be achieved by culturing the transduced cells with increasing doses of tet, whereby a concentration of 500 ng/mL tet in the culture medium abrogated IL-2 expression. Most importantly for clinical application, IL-2 expression by the transduced melanoma cells could also be regulated in vivo. When nu/nu mice were inoculated with the transduced tumor cells, they failed to develop tumors. Instead, the inhibition of IL-2 expression in the transduced tumor cells by oral administration of tet led to subcutaneous tumor growth; this growth rate was comparable with the growth rate of subcutaneously inoculated untransduced parental cells. The finding demonstrates the applicability of the tet-regulated system in cancer gene therapy

The acceleration of metastases after tumor removal and the paradoxical phenomenon of concomitant tumor resistance

Although surgical extirpation of tumors is usually clinically recommended, tumor removal may entail an undesired side effect: the risk of accelerating the growth of metastases. This effect may account for the relatively modest survival benefits observed when surgery is accomplished after tumor cells have already disseminated to distant anatomical sites even when tumor removal is combined with chemotherapy or immunotherapy. Although different mechanisms could contribute to the enhancement of residual tumor growth after tumor removal, probably a main effect is associated with the withdrawing of an inhibitory effect generated, by certain circumstances, by the primary tumor on its own metastases. This inhibitory effect is a particular case of a more general and paradoxical phenomenon known as concomitant tumor resistance (CR) in which a tumor-bearing host inhibits or retards the growth of secondary tumor implants despite the fact that the primary tumor grows progressively. In this essay we especially focus on the last investigations of our laboratory concerningthe importance of tyrosine isomers as mediators of the phenomenon of CR and on their capacity to inhibit established metastases. Taking into account that metastases are considered the main problem in cancer pathology, our investigations aimed to elucidate the molecular basis of the phenomenon of CR might stimulate the design of new and less harmful means of managing malignant diseases, especially by controlling the growth of metastases after the removal of a primary tumor, or after other injuries or stressors that have been claimed to promote the escape of metastases from dormancy.Fil: Montagna, Daniela Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Chiarella, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Meiss, Roberto P.. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Ruggiero, Raul Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; Argentin

Targeting hypoxia-inducible factor-1α (HIF-1α) in combination with antiangiogenic therapy: a phase I trial of bortezomib plus bevacizumab.

PurposeWe hypothesized that bortezomib, an agent that suppresses HIF-1α transcriptional activity, when combined with bevacizumab, would obviate the HIF-1α resistance pathway. The objectives of this phase I trial were to assess safety and biological activity of this combination.Experimental designPatients with advanced, refractory malignancies were eligible. Patients received bevacizumab and bortezomib (3-week cycle) with dose expansions permitted if responses were seen and for assessing correlates. Pharmacodynamic assessment included plasma VEGF, VEGFR2, 20S proteasome inhibition, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), and HIF-1α tumor expression.ResultsNinety-one patients were treated (median=6 prior treatments). The FDA-approved doses of both drugs were safely reached, and the recommended phase 2 dose (RP2D) is bevacizumab 15 mg/kg with bortezomib 1.3 mg/m(2). Four patients attained partial response (PR) and seven patients achieved stable disease (SD) ≥ 6 months (Total SD ≥ 6 months/PR=11 (12%)). The most common drug-related toxicities included thrombocytopenia (23%) and fatigue (19%). DCE-MRI analysis demonstrated no dose-dependent decreases in K(trans) although analysis was limited by small sample size (N=12).ConclusionCombination bevacizumab and bortezomib is well-tolerated and has demonstrated clinical activity in patients with previously treated advanced malignancy. Pharmacodynamic assessment suggests that inhibition of angiogenic activity was achieved

Targeting STAT3 in Cancer with Nucleotide Therapeutics.

Signal transducer and activator of transcription 3 (STAT3) plays a critical role in promoting the proliferation and survival of tumor cells. As a ubiquitously-expressed transcription factor, STAT3 has commonly been considered an "undruggable" target for therapy; thus, much research has focused on targeting upstream pathways to reduce the expression or phosphorylation/activation of STAT3 in tumor cells. Recently, however, novel approaches have been developed to directly inhibit STAT3 in human cancers, in the hope of reducing the survival and proliferation of tumor cells. Several of these agents are nucleic acid-based, including the antisense molecule AZD9150, CpG-coupled STAT3 siRNA, G-quartet oligodeoxynucleotides (GQ-ODNs), and STAT3 decoys. While the AZD9150 and CpG-STAT3 siRNA interfere with STAT3 expression, STAT3 decoys and GQ-ODNs target constitutively activated STAT3 and modulate its ability to bind to target genes. Both STAT3 decoy and AZD9150 have advanced to clinical testing in humans. Here we will review the current understanding of the structures, mechanisms, and potential clinical utilities of the nucleic acid-based STAT3 inhibitors

Complex Systems Analysis of Cell Cycling Models in Carcinogenesis

A new approach to the modular, complex systems analysis of nonlinear dynamics in cell cycling network transformations involved in carcinogenesis is proposed. Carcinogenesis is a complex process that involves dynamically inter-connected biomolecules in the intercellular, membrane, cytosolic, nuclear and nucleolar compartments that form numerous inter-related pathways referred to as networks.
The variable biotopology of such dynamic networks is highly complex, and has a number of interesting properties that can be formally characterized at one level of organization by mathematical structures called 'biogroupoids'. 
One such family of pathways contains the cell cyclins. Cyclins are proteins that link several critical pro-apoptotic and other cell cycling/ division components, including the tumor suppressor gene TP53 and its product, the Thomsen-Friedenreich antigen (T antigen), Rb, mdm2, c-Myc, p21, p27, Bax, Bad and Bcl-2, which all play major roles in carcinogenesis of many cancers. A novel theoretical analysis is thus possible based on recently published studies of cyclin signaling, with special emphasis placed on the roles of cyclins D1 and E, suggests novel clinical trials and rational therapies of cancer through reestablishment of cell cycling inhibition in metastatic cancer cells

Targeted therapy in melanoma

Malignant melanoma is a highly lethal disease unless detected early. Single-agent chemotherapy is well tolerated but is associated with very low response rates. Combination chemotherapy and biochemotherapy may improve objective response rates but do not prolong survival and are associated with greater toxicity. Immunotherapeutic approaches such as high-dose interleukin-2 are associated with durable responses in a small percentage of patients, but are impractical for many patients due to accessibility and toxicity issues. Elucidations of the molecular mechanisms of carcinogenesis in melanoma have expanded the horizon of opportunity to alter the natural history of the disease. Multiple signal transduction pathways seem to be aberrant and drugs that target them have been and continue to be in development. In this review we present data on the most promising targeted agents in development, including B-raf inhibitors and other signal transduction inhibitors, oligonucleotides, proteasome inhibitors, as well as inhibitors of angiogenesis. Most agents are in early phase trials although some have already reached phase III evaluation. As knowledge and experience with targeted therapy advance, new challenges appear to be arising particularly in terms of resistance and appropriate patient selection

Targeted Oral Delivery of Paclitaxel Using Colostrum-Derived Exosomes

Lung cancer is the leading cause of cancer-related deaths worldwide. Non-small-cell lung cancer (NSCLC) is the most common type accounting for 84% of all lung cancers. Paclitaxel (PAC) is a widely used drug in the treatment of a broad spectrum of human cancers, including lung. While efficacious, PAC generally is not well tolerated and its limitations include low aqueous solubility, and significant toxicity. To overcome the dose-related toxicity of solvent-based PAC, we utilized bovine colostrum-derived exosomes as a delivery vehicle for PAC for the treatment of lung cancer. Colostrum provided higher yield of exosomes and could be loaded with higher amount of PAC compared to mature milk. Exosomal formulation of PAC (ExoPAC) showed higher antiproliferative activity and inhibition of colony formation against A549 cells compared with PAC alone, and also showed antiproliferative activity against a drug-resistant variant of A549. To further enhance its efficacy, exosomes were attached with a tumor-targeting ligand, folic acid (FA). FA-ExoPAC given orally showed significant inhibition (\u3e50%) of subcutaneous tumor xenograft while similar doses of PAC showed insignificant inhibition. In the orthotopic lung cancer model, oral dosing of FA-ExoPAC achieved greater efficacy (55% growth inhibition) than traditional i.v. PAC (24–32% growth inhibition) and similar efficacy as i.v. Abraxane (59% growth inhibition). The FA-ExoPAC given i.v. exceeded the therapeutic efficacy of Abraxane (76% growth inhibition). Finally, wild-type animals treated with p.o. ExoPAC did not show gross, systemic or immunotoxicity. Solvent-based PAC caused immunotoxicity which was either reduced or completely mitigated by its exosomal formulations. These studies show that a tumor-targeted oral formulation of PAC (FA-ExoPAC) significantly improved the overall efficacy and safety profile while providing a user-friendly, cost-effective alternative to bolus i.v. PAC and i.v. Abraxane