Aim. The directed design and synthesis of new hybrid molecules containing [6+5]-heterocycles and thiazolidinone fragment, and their evaluation as potent anticancer agents. Methods. Organic synthesis, biological in vitro assays, SAR analysis, molecular docking, pharmacophore modelling. Results. A series of novel synthetic hybrid thiazolidinone-indole-carboxylates was designed, synthesized, and screened for their toxic activity towards the human hepatocarcinoma (HepG2), human glioblastoma (U251), human breast adenocarcinoma (MCF-7), and human promyelocytic leukemia (HL-60) cell lines. The lines of hepatocarcinoma, glioblastoma and breast adenocarcinoma were weakly sensitive to the studied compounds, the viability of the human promyelocytic leukemia cell line HL-60 was inhibited by 5-fluoro-3-[2-(4-hydroxyanilino)-4-oxo-thiazol-5-ylidene]methyl]-1H-indole-2-carboxylate at the micromolar concentration IC₅₀ = 8.36 μM. The cytotoxic action of this compound tested on a panel of cancer cell lines showed that the cell lines of leukemia, melanoma, and ovarian cancer were the most sensitive to it. Conclusions. The in vitro screening of biological effects of the synthesized compounds allowed identifying a hit-compound 2c with high antileukemic action and low toxicity towards pseudonormal murine fibroblasts (Balb/c3T3). In general, 4-thiazolidinone-indolecarboxylate 2c inhibited by > 50% the viability of 21 tumor cell lines. The in silico studies of putative binding mechanisms of the hit-compound 2c showed its high affinity to the colchicine site of cytoskeletal protein tubulin.