Three-dimensional (3D) cultures have the potential to increase the predictive value of pre-clinical drug research and bridge the gap towards anticipating clinical outcome of proposed treatments. However, their implementation in more advanced drug-discovery programs is still in its infancy due to the lack of reproducibility and low time- and cost effectiveness. HCT116, SW620 and DLD1 cells, cell lines with distinct mutations, grade and origin, were co-cultured with fibroblasts and endothelial cells (EC) in 3D spheroids. Clinically relevant drugs, i.e. 5-fluorouracil (5−FU), regorafenib and erlotinib, were administered individually to in CRC cell cultures. In this study, we established a robust, low-cost and reproducible short-term 3D culture system addressing the various complexities of the colorectal carcinoma (CRC) microenvironment. We observed a dose-dependent increase of erlotinib sensitivity in 3D (co-)cultures compared to 2D cultures. Furthermore, we compared the drug combination efficacy and drug-drug interactions administered in 2D, 3D and 3D co-cultures. We observed that synergistic/additive drug-drug interactions for drug combinations administered at low doses shifted towards additive and antagonistic when applied at higher doses in metastatic CRC cells. The addition of fibroblasts at various ratios and EC increased the resistance to some drug combinations in SW620 and DLD1 cells, but not in HCT116. Retreatment of SW620 3D co-cultures with a low-dose 3-drug combination was as active (88% inhibition, relative to control) as 5-FU treatment at high dose (100 μM). Moreover, 3D and 3D co-cultures responded variably to the drug combination treatments, and also signalling pathways were differently regulated, probably due to the influence of fibroblasts and ECs on cancer cells. The short-term 3D co-culture system developed here is a powerful platform for screening (combination) therapies. Understanding of signalling in 3D co-cultures versus 3D cultures and the responses in the 3D models upon drug treatment might be beneficial for designing anti-cancer therapies.

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.

A major limitation of clinically used cancer drugs is the lack of specificity resulting in toxicity. To address this, we performed a phenotypically-driven screen to identify optimal multidrug combinations acting with high efficacy and selectivity in clear cell renal cell carcinoma (ccRCC). The search was performed using the Therapeutically Guided Multidrug Optimization (TGMO) method in ccRCC cells (786-O) and nonmalignant renal cells and identified a synergistic low-dose four-drug combination (C2) with high efficacy and negligible toxicity. We discovered that C2 inhibits multipolar spindle pole clustering, a survival mechanism employed by cancer cells with spindle abnormalities. This phenotype was also observed in 786-O cells resistant to sunitinib, the first line ccRCC treatment, as well as in melanoma cells with distinct percentages of supernumerary centrosomes. We conclude that C2-treatment shows a high efficacy in cells prone to form multipolar spindles. Our data suggest a highly effective and selective C2 treatment strategy for malignant and drug-resistant cancers.