The impact of co-culture of NSCLC tumor cells and fibroblasts on drug response

Background: The role of stromal cells and the tumor microenvironment has been described to modulate cancer development and tumor drug sensitivity, in part due to the interaction with fibroblasts. Therefore, it is critical to incorporate this feature in our in vitro model and to evaluate its potential impact in early stages of drug development. Methods: Non Small Cell Lung Cancer (NSCLC) tumor cell aggregates were microencapsulated in alginate capsules, alone or in combination with fibroblasts (immortalized normal and cancer-associated fibroblasts – NFs and CAFs, and human dermal fibroblasts - hDFs), cultured during four weeks; and tumor growth and drug response, both in vitro and in vivo, were evaluated. Results: Microencapsulation of H1650 and H1437 spheroids in mono- or co-cultures with fibroblasts resulted in viable cultures with tumor aggregate increasing continuously during culture time. However, tumor growth in in vitro co-cultures was dependent on the source of fibroblast and cell line used. When challenged with drugs, co-cultures with fibroblasts in our in vitro 3D model presented, in general, lower sensitivity to therapy after 3 weeks of treatment. H1437+hDFs co-cultures showed less sensitivity to volasertib treatment, with higher DNA concentration (2-fold higher versus mono-cultures) and higher resazurin reduction activity (35% versus 22% in mono-cultures). H1650+NFs co-cultures also demonstrated lower sensitivity to erlotinib and docetaxel treatment, with higher resazurin reduction activity (71% versus 29% in mono-cultures) and higher viable area of aggregates, respectively. Mono and co-cultures can also be injected in mice for the generation of xenografts. Evaluation of tumor growth based on the local of injection, fibroblast source and drug response was compared. In agreement with the in vitro results, only co-culture of H1437+hDFs injected in the lungs significantly enhanced in vivo tumor growth. However, co-culture of H1650 with fibroblasts did not result in altered tumor growth in vivo. Conclusions: Altogether, we established a 3D model with co-culture of NSCLC tumor cell aggregates and fibroblasts that, depending on the pair used, presented reduced sensitivity to standard of care drugs, better reflecting the clinical observations. Legal entity responsible for the study: iBET/ITQB-UNL; AbbVie and Oncotest Funding: Innovative Medicines Initiative Joint Undertaking (IMI grant agreement n° 115188), resources composed of financial contribution from EU – FP7 and EFPIA companies in kind contribution. iNOVA4Health – UID/Multi/04462/2013, a program financially supported by Fundação para a Ciência e Tecnologia/Ministério da Educação e Ciência, through national funds and co-funded by FEDER under the PT2020 Partnership Agreement is also acknowledged. SA and MFE are recipients of PhD fellowships from FCT (PD/BD/105768/2014 and SFRH/BD/52208/2013, respectively). Disclosure: All authors have declared no conflicts of interest.