An autologous cell therapy batch is patient-matched: the cells that leave the patient by apheresis are the only ones that can be infused back. The total turnaround — "vein-to-vein time" T — is the sum of nine sequential stage durations, each shortened by automation and lengthened by mandatory hold/QC steps:
T = t_apheresis + t_ship_in + t_activation + t_transduction
+ t_expansion + t_harvest + t_QC_release + t_ship_out + t_infusion_prep
t_QC_release = { 2d rapid molecular, 7d standard compendial, 14d sterility culture }
t_stage(automation) = t_base × (1 − 0.35 × automation_fraction)
Clinical deterioration risk uses a logistic dose-response in elapsed days, reflecting real CAR-T programs where a slow-progressing lymphoma or leukemia patient can worsen while waiting:
P(deteriorate) = 1 / (1 + exp(−k × (T − T₀))) k≈0.09, T₀≈24 days
Chain-of-identity (mix-up) risk models the probability that a patient-matched product is misidentified somewhere across the pipeline. Each independent barcode/witness check multiplies the per-stage error probability by a large reduction factor (defense-in-depth), so risk falls roughly geometrically with the number of checks:
P(mix-up) = 1 − (1 − p_stage)^(9) , p_stage = p₀ × 0.35^(checks)
- Release testing method — the biggest single lever on turnaround: a 14-day sterility culture alone can double vein-to-vein time versus rapid molecular release.
- Automation / closed-system level — reduces manual hands-on time per stage and, independently, lowers the base per-stage mix-up probability.
- Chain-of-identity controls — redundant barcode/witness checkpoints (apheresis, cryostorage-in, activation, cryostorage-out, infusion) that catch a mislabeled bag before it reaches the wrong patient.
- Concurrent batches — more batches sharing a suite raises scheduling contention and throughput, visualised as parallel tracks.
Real-world relevance: this is the exact structure regulators and manufacturers optimize for approved CAR-T therapies (Kymriah, Yescarta, Abecma) — turnaround and chain-of-identity are the two axes that most often determine whether an eligible, deteriorating patient actually receives their own cells in time.