Abstract

Combinatorial Drug Screening on 3D Ewing Sarcoma Spheroids Using Droplet-based Microfluidics

Raphael Tomasi, Cofounder & CTO, Okomera

At Okomera, we develop a unique technology for miniaturized, automated and functional cell assays in precision cancer medicine. Our droplet microfluidic workflow enables to encapsulate patient cancer cells from a biopsy, and quickly form a single 3D microtumor per droplet. This versatile microfluidic toolbox enables sequential 3D co-culture, hydrogel encapsulation, fluorescent assays or multiplexing to up to 100 conditions per chip. Okomera provides a laboratory instrument, microfluidic consumables and an Artificial Intelligence-powered analysis software to extract quantitative features from microscopy images of the chip and assess drug efficacy ex vivo. Here, we applied concomitant and sequential drug combination of two chemotherapies, etoposide and cisplatin to the Ewing sarcoma cell line A673. Microtumors were formed in 500 nL droplets and then fused with secondary droplets containing fluorescent-barcoded drugs at different concentrations. Differences in microtumor growth and viability were analyzed on around 300 microtumors per experiment. This enabled accurate estimation of IC50 values for each drug, in agreement with measurements obtained in standard non adherent multiwell plates. Using this straightforward method, synergistic drug combination was found when both drugs were tested simultaneously or sequentially. Interestingly, sequential combination treatment with etoposide applied 24 h before cisplatin resulted in an amplified synergistic effect.