Recent Considerations in the Application of RAPTA-C for Cancer Treatment and Perspectives for Its Combination with Immunotherapies

The organometallic ruthenium(II) [Ru(arene)Cl2PTA] PTA - 1,3,5-triaza-7-phosphaadamantane compound, RAPTA-C, represents an innovative anti-cancer therapeutic and a better-tolerated alternative to platinum (Pt)-based chemotherapeutic drugs in the treatment of cancer. RAPTA-C exhibits anti-metastatic, anti-angiogenic, and anti-tumoral activities through protein and histone-deoxyribonucleic acid alterations. In comparison to other ruthenium-based drugs, which have been recently evaluated in clinical trials, RAPTA-C is strikingly competitive, especially when administered in combination with other targeted drugs. In this review, the uniqueness of RAPTA-C as an anti-cancer chemotherapeutic compared to metal-based drugs under clinical evaluation and those approved by the Food and Drug Administration is emphasized; specifically, comparing the application of RAPTA-C to platinum-based drugs, for example, cisplatin and oxaliplatin, as well as to prominent ruthenium-based compounds, such as NAMI-A imidazolium-trans-tetrachloro(dimethylsulfoxide) imidazoleruthenium(III) and trans-[tetrachlorobis (1Hindazole) ruthenate(III)] (KP1019)/(N)KP1339 (N)KP1339 - sodium. Additionally, the possible correlation between RAPTA-C and immune response modulation, as well as potential applications of RAPTA-C in combination with immune therapeutic regimens, is highlighted.

Screening-based approach to discover effective platinum-based chemotherapies for cancers with poor prognosis

Damiano Banfi, Paul Joseph Dyson, Fabien Kuttler, Gerardo Turcatti, Hristo Plamenov Varbanov

Drug combinations are extensively used to treat cancer and are often selected according to complementary mechanisms. Here, we describe a cell-based high-throughput screening assay for identification of synergistic combinations between broadly applied platinum-based chemotherapeutics and drugs from a library composed of 1280 chemically and pharmacologically diverse (mostly FDA approved) compounds. The assay was performed on chemoresistant cell lines derived from lung (A549) and pancreatic (PANC-1) carcinoma, where platinum-based combination regimens are currently applied though with limited success. The synergistic combinations identified during the screening were validated by synergy quantification using the combination index method and via high content fluorescent microscopy analysis. New promising synergistic combinations discovered using this approach include compounds currently not used as anticancer drugs, such as cisplatin or carboplatin with hycanthone and cisplatin with spironolactone in pancreatic carcinoma, and carboplatin and deferoxamine in non-small cell lung cancer. Strong synergy between cisplatin or carboplatin and topotecan in PANC-1 cells, compared to A549 cells, suggests that this combination, currently used in lung cancer treatment regimens, could be applied to pancreatic carcinoma as well. Several drugs used to treat diseases other than cancer, including pyrvinium pamoate, auranofin, terfenadine and haloprogin, showed strong cytotoxicity on their own and synergistic interactions with platinum drugs. This study demonstrates that non-obvious drug combinations that would not be selected based on complementary mechanisms can be identified via high-throughput screening.

2019

Innovative Tools and in vivo Methods for Tuberculosis Drug Discovery and Development

Raphael Christopher Sommer

Worldwide, tuberculosis (TB) is the leading cause of death due to a single infectious agent, claiming 1.6 million human lives and causing >10 million new cases in 2017 alone, mostly in low-income regions. The intracellular pathogen Mycobacterium tuberculosis is the etiological agent and generally infects the lungs. Although treatments exist, curing TB requires long and often expensive chemotherapy, frequently accompanied by undesirable side-effects. In the absence of an effective vaccine and with the increasing emergence of multidrug resistance, new and more powerful antibiotics are urgently needed to control the global TB crisis. In this respect, benzothiazinones (BTZs), a class of new anti-TB compounds, have recently been discovered. Macozinone (PBTZ169), that has reached phase I and II clinical trials in Switzerland and Russia, respectively, is undoubtedly the most promising drug of this category. We derivatized PBTZ169 into a fluorescent chemical probe that efficiently, covalently and selectively labels the enzyme DprE1, thereby localizing the target of BTZs to the periplasm at the poles of actinobacteria. We further discuss the potential applications of such probes for in vivo imaging, mycobacterial detection and designing new diagnostic tools. In general, the search for novel anti-mycobacterial drugs is an extremely long process, delaying the progression of new compounds down the pipeline and to the clinic. Assessing drug efficacy in vivo typically requires extensive resources and is time-consuming. This process can be shortened by applying alternative and innovative methods devised in this thesis, namely the implementation of in vivo imaging procedures and use of the zebrafish embryo model of mycobacterial infection for drug discovery and development. In vivo imaging enables bacterial loads in animal models to be assessed in real time, by means of fluorescence or bioluminescence imaging. We constructed, optimized and characterized genetically engineered near-infrared fluorescent reporters of the pathogens Mycobacterium marinum and M. tuberculosis that allow direct visualization of bacteria in infected zebrafish and mice, respectively. Furthermore, we show that the fluorescence level accurately reflects the bacterial load, as determined by colony forming unit enumeration, thus enabling the efficacy of antibiotic treatment to be assessed in live animals. Alternatively, we applied autobioluminescent M. tuberculosis to evaluate drug efficacy in mice and demonstrated that our system enables the therapeutic response to be followed in real time. Longitudinal imaging also reduces the number animals required thus providing a substantial gain of time and resources. Finally, the zebrafish embryo is an inexpensive and faster alternative model that has been applied to investigate mycobacterial pathogenesis. We implemented this model of M. marinum infection and successfully applied it to assess the activity of several drugs in vivo. Altogether, the innovative methods described in this work are advantageous for TB drug discovery and development, especially for the in vivo evaluation of new anti-mycobacterial candidates, and provide more ethically acceptable approaches and biomedical applications.

EPFL2019

Anti-angiogenic immunotherapy for lung cancer

Ece Kadioglu

Lung cancer is the leading cause of cancer-associated deaths worldwide. Platinum-based chemotherapy is the most common therapeutic approach in advanced non-small cell lung cancer (NSCLC), particularly for tumors that carry non-druggable activating mutations. However, these tumors are generally not eradicated when diagnosed at an advanced stage and are frequently resistant to chemotherapy. Therefore, there is an urgent medical need for new treatments for this frequent cancer type. Immunotherapies are treatments based on increasing the strength of immune responses against cancer. In particular, monoclonal antibodies that block inhibitory "immune-checkpoints" expressed on T cells (e.g., programmed cell death protein 1, or PD1) show clinical efficacy in increasing tumor types. However, these therapies improve survival in only a minority of NSCLC patients, and ongoing efforts are being made for increasing their efficacy through combinatorial treatments. In this regard, growing evidence indicates that tumor angiogenesis is closely associated with immunosuppression. Pro-angiogenic factors, such as vascular endothelial growth factor A (VEGFA) and angiopoietin 2 (ANG2), cause abnormalities and dysfunctions in tumor blood vessels that impair T cell extravasation and anti-tumoral activity. Recent findings in preclinical cancer models show that reprogramming the features of tumor-associated blood vessels by anti-angiogenic drugs may help to increase intratumoral T cell abundance and sensitize refractory tumors to immunotherapy. Nevertheless, the potential of anti-angiogenics in the context of lung cancer immunotherapy is poorly understood. Therefore, the main objective of my project was to audit combinations of anti-angiogenic therapy and immune checkpoint blockade in a genetically engineered mouse model of NSCLC. I first studied the anti-tumoral activity of dual VEGFA and ANG2 inhibition using a bispecific antibody (A2V) in the KrasLSL-G12D/+;p53fl/fl (KP) NSCLC model. I found that A2V, but not single VEGFA or ANG2 blockade, had robust tumor-inhibitory activity in KP mice, which was at least comparable to standard-of-care chemotherapy. However, A2V only moderately increased cytotoxic T cells in the tumors. To potentially increase the immunogenicity of KP tumors, I also generated two KP mouse variants by either co-expressing a surrogate neoantigen or genetically deleting a DNA mismatch repair enzyme in the cancer cells. However, the therapeutic efficacy of A2V was not further improved in spite of a slightly more activated immune response. I next investigated combination therapies involving A2V and PD1 blockade. In contrast to previous findings in other cancer types, the addition of PD1 antibodies deteriorated the efficacy of A2V, likely through enhancing immunosuppressive mechanisms sustained, at least in part, by regulatory T cells and T cell-antagonizing cytokines. In summary, my work supports the potential clinical efficacy of combined VEGFA and ANG2 blockade for lung cancer therapy but provided little evidence for its synergy in association with anti-PD1 therapy.

EPFL2019

Anti-angiogenic immunotherapy for lung cancer

Ece Kadioglu

EPFL2019

Innovative Tools and in vivo Methods for Tuberculosis Drug Discovery and Development

Raphael Christopher Sommer

EPFL2019