Presentation on theme: "EPAA meeting November 2007 1 In vitro 3T3 NRU Phototoxicity test: Ann De Smedt."— Presentation transcript:
EPAA meeting November In vitro 3T3 NRU Phototoxicity test: Ann De Smedt
EPAA meeting November Topics Background The in vitro 3T3 NRU Phototoxicity Test Test strategy & Results Post acceptance evaluation
EPAA meeting November Background In vitro 3T3 NRU phototoxicity test determines the potential of chemicals to cause phototoxicity following exposure to UVA radiation (315 – 400 nm) Phototoxicity – is defined as a toxic acute response from a substance applied to the body which is either elicited or increased after subsequent exposure to light, or that is induced by skin irradiation after systemic administration of a substance. (OECD432). EU guidance differs from FDA guidance
EPAA meeting November In vitro 3T3 NRU phototoxicity test I. Treatment of 3T3 cells II. Irradiation 5J UVA - UVA h incubation Neutral Red Uptake determination Balb/c 3T3 cells X 24 h incubation 1 h treatment Seeding cells
EPAA meeting November UV + UV IC 50 PIF=IC 50 /IC 50 PROBABLE Phototoxic NO Phototoxic Phototoxic PIF<2 2
EPAA meeting November Testing strategy at J&J NO further testing NO No further testing NEGATIVE In vitro 3T3 NRU phototoxicity test YES UV/VIS-Absorption and Skin and Eye accumulation or Topical application No further testing NEGATIVE Phototox label POSITIVE In vivo phototoxicity test in pigmented rats POSITIVE
EPAA meeting November Compounds Tested 43 JNJ-compounds tested in vitro 13 compounds POSITIVE NEGATIVE False positive results?? 6 compounds tested in vivo 30 compounds NEGATIVE (70 %)
EPAA meeting November High rate of false positive results Doubts about use of validated in vitro 3T3 NRU phototoxicity test Lead to a lot of follow-up work More in vivo tests needed Post-acceptance evaluation ? ICH guidelines?
EPAA meeting November Post-acceptance evaluation Concentration of compound Maximum tested concentration: OECD: 1000 g/ml EU guidance: 100 g/ml or highest achievable Correlation in vitro results with in vivo results Is there any skin/eye absorption levels that triggers testing? Thresholds? What to do with insoluble compounds? Importance of light source? during validation study same source used Importance of UVA/UVB? OECD guideline: not specified EU guidance: 20/1 at J&J: 174/1 Light source
EPAA meeting November Post-acceptance evaluation validation study: mainly chemicals Compounds post-validation: a lot of pharmaceuticals tested correlation with in vivo? which in vivo test? what about 3D human skin models as follow-up studies? Tiered approach?
EPAA meeting November EFPIA survey !! DIA Workshop (21-22 Nov, 2007, Amsterdam) Post-acceptance evaluation Recent initiatives:
EPAA meeting November Thank you!
EPAA meeting November Back-up slides
EPAA meeting November Differences in guidelines (phototox) Directive 86/609/EEC Note for Guidance on Photosafety Testing (2002) Guidance for Industry: Photosafety Testing (2003) FDA EMEA Encourage use of validated in vitro method on all photoreactive compounds bioavailable to skin or eye regardless of level of exposure. In vivo non-clinical studies not warranted Possible clinical follow up MED in volunteers Encourages use of traditional animal tests, perhaps followed by clinical studies on photoreactive compounds bioavailable in skin or eyes (at levels sufficient to cause photoirritation, clinical evidence or class effect). driven by