Table 2.
Proposed minimum release panel for iPSC-derived CAR-NK EV/sEV products.
| Release domain | Minimum attribute | Example assay or readout | Rationale |
|---|---|---|---|
| Identity | Particle size distribution | NTA, TRPS, DLS, TEM or cryo-EM | Confirms sEV-enriched particle profile and detects aggregation |
| Identity | Particle concentration | NTA, TRPS, high-sensitivity flow or orthogonal particle counting | Defines dose input and lot-to-lot particle consistency |
| Identity | EV-associated markers | CD9, CD63, CD81, TSG101, ALIX by immunoblot, ELISA, bead-based flow or single-EV analysis | Confirms EV/sEV enrichment |
| Identity | NK-related markers | CD56, CD16, NKG2D, DNAM-1 or other product-relevant markers | Confirms source-cell-related EV features where incorporated |
| Identity | CAR-positive EV fraction | Bead-based flow cytometry, ELISA, antigen-capture assay, single-EV imaging | Quantifies the fraction of EVs carrying the targeting module |
| Identity | CAR density | CAR signal per particle-equivalent dose, antigen-binding units, single-EV or calibrated bead assay | Supports dose normalization and lot comparability |
| Identity | Producer-cell identity | iPSC-CAR-NK cell phenotype, CAR copy/insertion characterization, NK differentiation markers | Links final EV product to the intended producer-cell platform |
| Purity | Residual host-cell DNA | qPCR, PicoGreen, ddPCR | Controls producer-cell and process-related nucleic acid impurities |
| Purity | Residual host-cell proteins | Total protein profile, host-cell protein assay, proteomics | Detects non-vesicular protein contamination |
| Purity | Albumin/lipoprotein contamination | Albumin, ApoA1, ApoB or lipoprotein particle assays | Distinguishes EVs from common extracellular contaminants |
| Purity | Cellular debris markers | Calnexin, GM130, cytochrome c or other depleted markers | Demonstrates depletion of intracellular organelle or cell-fragment contaminants |
| Purity | Residual cytokines | Free IL-15, IL-2, IL-12, IL-18 or process-specific cytokines | Controls carryover that could cause unintended immune activation |
| Purity | Residual free targeting ligand | Free antibody, soluble CAR-binding ligand, free scFv or Fc-binding reagent | Distinguishes EV-associated targeting from soluble ligand carryover |
| Safety | Sterility | Compendial sterility test or validated rapid microbiological method | Required microbiological safety attribute |
| Safety | Endotoxin | LAL or recombinant factor C assay | Controls innate immune activation risk |
| Safety | Mycoplasma | Culture, PCR or validated rapid test | Required safety testing for cell-derived products |
| Safety | Adventitious-agent risk | Process-specific viral and adventitious-agent testing | Addresses producer-cell and culture-material risks |
| Potency | Antigen-specific binding or uptake | Antigen-positive versus antigen-negative NSCLC cells; quantitative uptake imaging or flow assay | Demonstrates target-dependent engagement |
| Potency | Dose-response cytotoxicity | Viability, apoptosis, impedance or live-cell imaging assay across EV dose range | Defines functional activity and dose response |
| Potency | CAR-dependence | Antigen blockade, soluble antigen competition, CAR-negative EV control | Confirms that activity depends on CAR-mediated targeting |
| Potency | Cytotoxic cargo | Granzyme B, perforin, FasL, TRAIL by ELISA, immunoblot or proteomics | Supports mechanism-linked cargo comparability |
| Potency | TME modulation, if claimed | Macrophage polarization, dendritic-cell activation, T-cell recruitment, TGF-β pathway readout | Required only if immunomodulatory claims are made |
| Potency bridging | In vivo or surrogate bridge | Tumor-control model, biodistribution-linked exposure assay, validated in vitro surrogate | Tests whether in vitro potency predicts in vivo activity |
| Comparability | Matrixed lot analysis | Particle number, CAR-positive fraction, cargo content, killing activity, impurity profile across lots | Establishes batch consistency and release acceptance ranges |
The table lists proposed release attributes for identity, purity, safety, potency, and potency bridging. This panel is intended as a translational framework rather than a finalized regulatory specification. Assays and acceptance criteria should be product-specific and justified by the proposed mechanism of action, manufacturing process, route of administration, and nonclinical validation data. EV terminology and reporting should follow MISEV2018 and EV-TRACK principles, including transparent reporting of producer-cell source, culture conditions, isolation and purification methods, EV-associated markers, negative or depleted markers, impurities, and functional assays.