Preclinical Models for Developing Therapy for Pediatric Solid Tumors Preclinical Models for Developing Therapy for Pediatric Solid Tumors uses and limitations Peter J. Houghton, Ph.D. Solid Malignancies Program St. Jude Children’s Research Hospital

Problems in using Preclinical Data Early drug discovery is conducted under defined/standardized environment.Early drug discovery is conducted under defined/standardized environment. Pediatric cancer models are not part of this process either in industry or NCI.Pediatric cancer models are not part of this process either in industry or NCI. Preclinical data using pediatric models are generated in an uncontrolled or regulated environment.Preclinical data using pediatric models are generated in an uncontrolled or regulated environment. Such data are derived from experimental systems that are not validated using experimental design and interpretation that lacks consistency or rigor.Such data are derived from experimental systems that are not validated using experimental design and interpretation that lacks consistency or rigor.

Informative Non-Clinical Data Pharmacology and pharmacokineticsPharmacology and pharmacokinetics SafetySafety EfficacyEfficacy BehaviourBehaviour Long term effectsLong term effects Developmental aspectsDevelopmental aspects Other? PharmacodynamicsOther? Pharmacodynamics

Uses: Where Do Animal Models Fit in Drug Development for Childhood Cancer? Drug acquired NCI/Industry/Academia Phase I Phase II Identification of active agents/analogsIdentification of active agents/analogs Optimization of administration schedulesOptimization of administration schedules and drug combinations. and drug combinations. Prioritization of agents for phase IPrioritization of agents for phase I Rational decisions to advance/stop developmentRational decisions to advance/stop development Potential to focus phase II trialsPotential to focus phase II trials Potential to relate target inhibition toPotential to relate target inhibition to biological response

Models Identify Clinically Active Agents Prospectively RHABDOMYOSARCOMA COLON CARCINOMA

SENSITIVITY OF WILMS TUMOR XENOGRAFTS

Topotecan Lactone AUC Associated with Response in Neuroblastoma Xenografts AUC (ng-hr/mL) NB1382.2NB1643NBEBNB1771NB1691 PRCR 290

Targeted Topotecan Neuroblastoma Protocol NB Courses; 92% Targeting Success Results u 28 evaluable patients u TPT median dose 3.0 mg/m 2 u 17 partial responses (60%) u 11 stable disease u no tumor progressions PKStudies Dose Adjustment Schema (100 ± 20 ng*hr/ml) (100 ± 20 ng*hr/ml) Day TPT TPT TPT TPT TPT X X TPT TPT TPT TPT TPT DoseAdjust TPT AUC 100 ± 20 ng*hr/ml Santana et al.(submitted)

Retrospective Analysis of Response-Exposure Relationships for Pediatric Tumors Xenografts Relationships for Pediatric Tumors Xenografts Drugs that failed Drugs that worked

Evaluation of MGI-114 (Phase II in COG?) Systemic exposure is still > 10-fold higher than in

Schedule-dependent antitumor activity of topotecan Control TPT (daily x 5) every 21 days Total dose = 22.5 mg/kg TPT (daily x 5) x 2 every 21 days Total dose = 22.5 mg/kg Tumor volume (cm 3 ) WeekWeek Week

ControlCarboplatin CisplatinOxaliplatin Discriminating Between Analogs: Osteosarcoma Models

The Challenge of Molecularly- Targeted Drugs The Challenge of Molecularly- Targeted Drugs Tumor models must accurately recapitulate activity of signal transduction pathways. -orthotopic or subcutaneous? - expression profiling - proteomics profilingTumor models must accurately recapitulate activity of signal transduction pathways. -orthotopic or subcutaneous? - expression profiling - proteomics profiling

WT6 vs parent WT8 vs parent XENOGRAFT XENOGRAFT PRIMARY TUMOR

P. Hedge et al. ASCO #535A GSK/Cytokinetics

Evaluation of SB Study #Tumor15 mg/kg10 mg/kg mg/kg Tox deaths 1998SKNEP+--0/50/5 1999SKNEP+++--2/51/5 2005SJ-WT /50/5 2009SJ-WT : CR CR with regrowth ++++: all tumors have partial reg regression (PR > 50% vo lumereduction) +++:stabl e di sease ++: grow growth delay ~ 2 tumor volume doublingtimes +:growth del ay ~ 1tumor vo volum e d oubling time -: n o grow th inhibition

Study 2026 SJ-WT10

Informative Non-Clinical Data Pharmacology and pharmacokineticsPharmacology and pharmacokinetics SafetySafety EfficacyEfficacy BehaviourBehaviour Long term effectsLong term effects Developmental aspectsDevelopmental aspects Other? PharmacodynamicsOther? Pharmacodynamics

PI-3K Targets of Cap Dependent Translation Cyclin D1 ODC1 MYC HIF1  Akt p70S6K mTOR IRS-1 PDK1/2 PTEN GTPGDP Rhe b mLST8 Raptor 4E-BP1 eIF4 E IGF-II TSC1 TSC2 AMPK AMP Low Energy (High AMP) Low Amino Acid Pools eIF4 E eIF4G TOP Dependent Translation ? Increased translation GTP LKB1 Rapamycin (CCI-779) TARGET INHIBITION IGF-II BIOLOGICAL READOUT PHARMACOKINETICS

Developing Initiatives for a National Consortium to Identify and Prioritize New Agents RFA to systematically characterize models through genomic/proteomic screens to identify potential molecular targets (POPP-TAP).RFA to systematically characterize models through genomic/proteomic screens to identify potential molecular targets (POPP-TAP). RFP to establish preclinical screening program that will identify agents having high priority for pediatric Phase I testing through the Children’s Oncology Group.RFP to establish preclinical screening program that will identify agents having high priority for pediatric Phase I testing through the Children’s Oncology Group.

Effective use of Non-clinical Data Standardization of experimental procedures: difficult, but a realistic goal.Standardization of experimental procedures: difficult, but a realistic goal. Standardization of acceptable criteria for assessing drug activity.Standardization of acceptable criteria for assessing drug activity. GLP compliance: very expensive, most academic centers would be excluded.GLP compliance: very expensive, most academic centers would be excluded.