title: A review of study designs and outcomes of phase I clinical studies of nanoparticle agents compared with small-molecule anticancer agents.
abstract: OBJECTIVE
  Nanoparticles or carrier-mediated agents have been designed to prolong drug circulation time, increase tumor delivery, and improve therapeutic index compared to their small-molecule counterparts. The starting dose for phase I studies of small molecules and nanoparticles anticancer agents is based on the toxicity profile of the most sensitive species (e.g., rat or canine), but the optimal animal model for these studies of nanoparticles is unclear. The objective of this study was to evaluate the design, progression, and outcomes of phase I studies of nanoparticles compared with small-molecule anticancer agents.
  
  
  METHODS
  In preclinical studies, the maximum tolerated dose (MTD) in rats and dogs was evaluated for nanoparticles and their respective small molecules. In phase I clinical trials in patients with advanced solid tumors, the basis for starting dose, the number of dose escalations, number of patients enrolled, and the ratio of MTD to starting dose was determined for nanoparticles and small molecules.
  
  
  RESULTS
  The mean ratio of MTD to starting dose in clinical phase I studies was significantly greater for nanoparticles (13.9 ± 10.8) compared with small molecules (2.1 ± 1.1; P = 0.005). The number of dose levels in a clinical phase I study was also significantly greater for nanoparticles (7.3 ± 2.9) compared with small molecules (4.1 ± 1.5; P = 0.008).
  
  
  CONCLUSIONS
  The degree of dose escalation from starting dose to MTD was significantly greater for nanoparticles as compared with small-molecule anticancer drugs. These findings necessitate the need to identify the most appropriate preclinical animal model to use when evaluating nanoparticles toxicity.
authors.affiliation: Division of Pharmacotherapy and Experimental Therapeutics, University of North Carolina (UNC) Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, , Chapel Hill, NC 27599, USA.
authors.forename: Whitney P
authors.initials: WP
authors.lastname: Caron
authors.forename: Katherine P
authors.initials: KP
authors.lastname: Morgan
authors.forename: Beth A
authors.initials: BA
authors.lastname: Zamboni
authors.forename: William C
authors.initials: WC
authors.lastname: Zamboni
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000009:adverse effects / Q000737:chemistry; D017321:Clinical Trials, Phase I as Topic; D004195:Disease Models, Animal; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D016503:Drug Delivery Systems; D006801:Humans; D020714:Maximum Tolerated Dose; D053758:Nanoparticles / Q000008:administration & dosage* / Q000009:adverse effects / Q000737:chemistry; D009369:Neoplasms / Q000188:drug therapy* / Q000473:pathology; D009374:Neoplasms, Experimental / Q000188:drug therapy* / Q000473:pathology; D051381:Rats
chemical_list: D000970:Antineoplastic Agents