Poor drug distribution as a possible explanation for the results of the PRECISE trial.
OBJECTIVE
Convection-enhanced delivery (CED) is a novel intracerebral drug delivery technique with considerable promise for delivering therapeutic agents throughout the CNS. Despite this promise, Phase III clinical trials employing CED have failed to meet clinical end points. Although this may be due to inactive agents or a failure to rigorously validate drug targets, the authors have previously demonstrated that catheter positioning plays a major role in drug distribution using this technique. The purpose of the present work was to retrospectively analyze the expected drug distribution based on catheter positioning data available from the CED arm of the PRECISE trial.


METHODS
Data on catheter positioning from all patients randomized to the CED arm of the PRECISE trial were available for analyses. BrainLAB iPlan Flow software was used to estimate the expected drug distribution.


RESULTS
Only 49.8% of catheters met all positioning criteria. Still, catheter positioning score (hazard ratio 0.93, p = 0.043) and the number of optimally positioned catheters (hazard ratio 0.72, p = 0.038) had a significant effect on progression-free survival. Estimated coverage of relevant target volumes was low, however, with only 20.1% of the 2-cm penumbra surrounding the resection cavity covered on average. Although tumor location and resection cavity volume had no effect on coverage volume, estimations of drug delivery to relevant target volumes did correlate well with catheter score (p < 0.003), and optimally positioned catheters had larger coverage volumes (p < 0.002). Only overall survival (p = 0.006) was higher for investigators considered experienced after adjusting for patient age and Karnofsky Performance Scale score.


CONCLUSIONS
The potential efficacy of drugs delivered by CED may be severely constrained by ineffective delivery in many patients. Routine use of software algorithms and alternative catheter designs and infusion parameters may improve the efficacy of drugs delivered by CED.
Sampson
John H
JH
Division of Neurosurgery, Department of Surgery, Duke University, Durham, North Carolina, USA. john.sampson@duke.edu
Archer
Gary
G
Pedain
Christoph
C
Wembacher-Schröder
Eva
E
Westphal
Manfred
M
Kunwar
Sandeep
S
Vogelbaum
Michael A
MA
Coan
April
A
Herndon
James E
JE
Raghavan
Raghu
R
Brady
Martin L
ML
Reardon
David A
DA
Friedman
Allan H
AH
Friedman
Henry S
HS
Rodríguez-Ponce
M Inmaculada
MI
Chang
Susan M
SM
Mittermeyer
Stephan
S
Croteau
David
D
Puri
Raj K
RK
D000465:Algorithms; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D001932:Brain Neoplasms / Q000188:drug therapy*; D002404:Catheterization / Q000379:methods* / Q000706:statistics & numerical data; D017326:Clinical Trials, Phase III as Topic / Q000379:methods; D018481:Convection; D016503:Drug Delivery Systems / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D018793:Interleukin-13; D053208:Kaplan-Meier Estimate; D016016:Proportional Hazards Models; D016032:Randomized Controlled Trials as Topic / Q000379:methods*; D012189:Retrospective Studies; D012984:Software; D014018:Tissue Distribution; D017211:Treatment Failure
D000970:Antineoplastic Agents; D018793:Interleukin-13