The differential staining cytotoxicity (DiSC) assay involves in vitro drug
panel testing against patient tumor cells to identify optimal therapy. This
observational study investigated whether DiSC assay guided treatment could
improve outcome in patients with chronic lymphocytic leukemia. A cohort of 178
patients were categorized either as sensitive to drugs in vitro and receiving
a sensitive drug in vivo, sensitive in vitro but not treated with a sensitive
drug, or having disease resistant to all drugs tested in vitro. Response and
survival for these patient categories were compared using multivariate
regression techniques. Patients receiving a sensitive drug, compared with
those who though having sensitivity did not, had a higher remission rate (odds
ratio, 6.5; 95% CI, 2.91–14.53) and reduced death rate (hazard ratio,
0.29; 95% CI, 0.16–0.53). Having adjusted for all known confounding
factors, the results suggest that in vitro drug sensitivity is an important
independent prognostic variable to include in future trials, and that the DiSC
assay may be a cost-effective use of health resources: the estimated
incremental cost-effectiveness was £1,470 per life-year gained. A
randomized controlled trial is required to confirm the benefit and estimate
reliably the potential impact of assay-guided choice of therapy.