The use of plastic microfluidic devices made using cyclic olefin polymer (COP) have also been proposed by Aref et al. for testing of immune checkpoint blockade (ICB) in conjunction with small hydrophobic molecules, as these can be adsorbed by PDMS.62 Murine- and patient-derived organotypic tumor spheroids from a patient with a small intestinal neuroendocrine tumour (SI-NET) were treated with ICB treatment with anti-PD-1 + anti-CTLA-4 in combination and as monotherapy. Here, PDCD1 is linked to neoplasm.