The pharmaceutical industry is facing high attrition rates of up to 95% in the field of cancer treatment in the clinical phase causing enormous costs 1-5. One reason for this deficit is the fact that currently efficacy of potential new compounds is assessed in large-scale screenings on 2D cell cultures of cancer cell lines or in animal models. Animal models have a higher complexity but there are crucial differences between mice and men 6,7. In the last decade, 3D cancer models using different approaches have been generated to bridge the gap between 2D culture of cancer cell lines and a complex in vivo tumor 6,8,9. The impact of 3D environment on cell differentiation and also on signaling has been shown in several studies years ago (e.g., by Mina Bissell) 10,11. Today, many 3D cell culture models are available such as spheroid cultures, hydrogels or microfluidic chips 12-16. Even though these models enhance complexity compared to conventional 2D culture systems, they mostly lack a tissue microenvironment that is known to have tumor-supporting effects and also impacts drug efficacy.
To address this issue, we generated a 3D tumor model based on a biological scaffold called SISmuc (small-intestine-submucosa + mucosa) that is derived from a decellularized porcine jejunum. Thereby, the tissue architecture and important components of the ECM such as different collagens as well as the basement membrane structure are preserved 17. This unique feature is crucial for tumor model generation of carcinomas that arise from epithelia and comprise about 80% of solid tumors. Furthermore, the proliferation rate in our tissue-engineered tumor model is reduced compared to the artificially high rates achieved in 2D culture. As proliferation is an important parameter in assessing drug efficacy, drug testing is enabled in our model in more similar conditions to in vivo tumors 17.
In order to evaluate the potential of our model to predict biomarker-dependent drug efficacy correctly, we here present data for two different lung cancer cell lines that differ in their EGFR-biomarker status. This mutational status has started to be determined routinely in NSCLC patients. Targeted treatments with TKIs such as the EGFR-inhibitor gefitinib against tumors bearing an activating EGFR mutation show superior outcomes compared to those with platinum-based chemotherapy 18-21.
We established several read-out techniques that are relevant for evaluating compound efficacy. Furthermore, after TGF-beta-1 stimulation we are able to investigate compound actions in tumor cells that started the EMT process, which is thought to be an important step in malignant transformation 22,23 and which is connected to drug resistance 24.
The 3D tumor model allow monitoring cell-specific responses to targeted treatments, chemotherapy, or drug combinations with good contrasts. To further enhance and speed up drug-screening and to encounter resistance, this is complemented by an in silico simulation. Based on a few experiments, the tumor response can be predicted in silico regarding the outcome for a full range of drugs and their combinations.