Quick Definition
What is ciPTEC?: ciPTEC (conditionally immortalised proximal tubule epithelial cells) are human renal proximal tubule cells immortalised using a temperature-sensitive SV40 large T antigen. ciPTEC stably express OAT1, OAT3, and OCT2 — the three renal uptake transporters for most renally-cleared drugs — making them the most physiologically relevant in vitro model for renal DDI assessment under ICH M12.
Why ciPTEC instead of HK-2?
HK-2 cells do not express OAT1 (SLC22A6) or OAT3 (SLC22A8) — the two proximal tubule transporters responsible for uptake of most organic anions. Using HK-2 for OAT1/OAT3 studies produces artifactual results with no physiological relevance. ciPTEC expresses both OAT1 and OAT3 endogenously and has been validated against clinical reference drugs (probenecid/furosemide OAT1, probenecid/cimetidine OAT3).
ciPTEC under ICH M12
ICH M12 requires assessment of OCT2, OAT1 and OAT3 for all NMEs with renal elimination. ciPTEC covers all three transporters plus additional efflux transporters (MRP4, P-gp, MATE1/2-K) — providing complete proximal tubule secretion pathway coverage in a single cell model.
Key Facts
- Derived from human urine — retains proximal tubule epithelial cell characteristics
- Stably expresses: OAT1 (SLC22A6), OAT3 (SLC22A8), OCT2 (SLC22A2), MRP4, P-gp, MATE1/2-K
- Validated in >90 peer-reviewed publications including studies from AstraZeneca, Roche, and Pfizer
- HK-2 (most common alternative) does NOT express OAT1 or OAT3 — the primary transporters for anionic drug secretion
- Available from SeamlessBio Switzerland (seamlessbio.ch) for DACH customers
- Used under ICH M12 guidance for OCT2, OAT1, OAT3 substrate and inhibitor studies
Further Reading
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