Efficacy tests are the cornerstone of effective cell therapies, but they can also be a source of delays during product development[3]. According to available information, efficacy tests represent a critical quality metric that expresses the biological ability of a product to achieve a clinical outcome[4]. The development of these tests is a complex challenge requiring detailed characterization of process parameters and quality attributes during preclinical and clinical development[4]. Industry faces capacity constraints in routine product testing and analytical assay development, which has caused significant challenges including delays in product development, delivery, clinical trials and regulatory approvals[5]. Experts recommend starting the development of own tests as early as possible and performing validations in an appropriate phase of development[5]. Without validated efficacy tests, a therapeutic product cannot be approved, as demonstrated by a recent FDA case where a product with excellent clinical results was not approved precisely because of insufficient evidence of efficacy[5].