This study evaluates the oncolytic potential of the Moscow strain of reovirus against human metastatic melanoma and glioblastoma cells. The Moscow strain effectively infects and replicates within human melanoma cell lines and primary glioblastoma cells, while sparing non-malignant human cells. Infection leads to the selective destruction of neoplastic cells, mediated by functional viral replication. A positive correlation was identified between viral RNA accumulation and tumor cell death, with no replication observed in non-malignant cells. This study highlights the critical roles of cathepsins B, L, and S as mediators of the oncolytic process. The pharmacological inhibition of these enzymes significantly attenuated reovirus-induced cytotoxicity in melanoma and glioblastoma cells. Conversely, PKR production analysis revealed minimal activation in reovirus-infected tumor cells, suggesting that the hyperactivation of the RAS-signaling pathway and subsequent PKR inhibition do not directly contribute to the selective efficacy of reovirus. Moreover, infected tumor cells exhibited features of both apoptotic and non-apoptotic death, emphasizing the intricate mechanisms of reovirus-mediated oncolysis. These findings underscore the therapeutic promise of the Moscow strain of reovirus as a selective and potent oncolytic agent for targeting melanoma and glioblastoma cells.

Introduction. Trastuzumab is the first known anti-HER2 agent, which revolutionized the treatment of one of the most common cancer types – breast cancer. Despite trastuzumab being approved long time ago, further improvement of related analytical methods remains relevant primarily due to the emergence of new biosimilars. For instance, immunogenicity – adverse reaction which is usually associated with biological drugs, can still be relevant for trastuzumab. Anti-drug antibodies, including neutralizing antibodies, caused by trastuzumab therapy, can affect drug effectiveness and safety profile.Aim. The aim of this study was to develop and validate the analytical method for neutralizing anti-trastuzumab antibodies determination in human blood serum.Materials and methods. The neutralizing anti-trastuzumab antibody determination was carried out by the competitive ELISA method, using spectrophotometric detection in the visible range of the spectrum.Results and discussion. The developed method was validated for cut-point, selectivity, sensitivity, specificity, precision and stability (short-term and long-term). To decrease the background noise from non-specific binding of sera components, the minimum required dilution value was determined at 0.5 % serum. The calculated value for cut-point was 14.62 %. The sensitivity of the developed method was estimated at 1985.2 ng/mL of neutralizing anti-trastuzumab antibodies.Conclusion. The obtained results allowed us to apply the developed ELISA method for the neutralizing anti-trastuzumab antibodies determination in human blood serum during trastuzumab immunogenicity assessment in bioequivalence clinical trials.