PRECLINICAL PHARMACOLOGY & TOXICOLOGY OF ANTI-NEOPLASTIC AGENTS  THE NCI PERSPECTIVE Joseph E. Tomaszewski, Ph.D. Toxicology & Pharmacology Branch DTP, DCTD, NCI

PRECLINICAL PHARMACOLOGY & TOXICOLOGY: WHY? Balance of: Regulatory Issues Need for information Science Practical Considerations Preclinical Costs versus Patient Cost

(Excluding Anti-Infectives) Lack of Efficacy 46.0% Commercial Reasons 7.0% ADRs in Man 16.0% PK 7.0% Animal Toxicity 17.0% Misc 7.0% Lack of Efficacy 30.0% Commercial Reasons 5.0% ADRs in Man 10.0% PK 39.0% Animal Toxicity 11.0% Misc 5.0% J. Ormerod (1994) Data taken from 7 UK-owned Companies ( ) REASONS FOR TERMINATION OF DEVELOPMENT OF NCEs

REGULATORY CONSIDERATIONS FOR PRE- CLINICAL DEVELOPMENT OF ANTICANCER DRUGS [DeGeorge, et al, CCP (1998) 41: ] “… The types of preclinical studies expected for support of clinical trials and marketing of a new drug depends on both the intended use of the drug and the population of patients being studied and treated. In situations where potential benefits are greatest (Advanced, life- threatening disease), greater risks of treatment toxicity can be accepted and the required preclinical testing can be minimal. …”

FDA PRECLINICAL PHARMACOLOGY & TOXICOLOGY REQUIREMENTS DRUGS Two Species - Rodent & Non-rodent Clinical Route & Schedule Follow NCI Guidelines Pharmacokinetics - Optional BIOLOGICALS Most Relevant Species Clinical Route & Schedule

REPRESENTATIVE SURFACE AREA TO WEIGHT RATIOS (km) FOR VARIOUS SPECIES 1 ((Freireich, et al, Cancer Chemother Repts, 1966, 50, ))

NCI STANDARDIZED PRECLINICAL TOXICOLOGY PROTOCOLS FOR ANTI-NEOPLASTIC AGENTS ( ) Mouse Lethality Studies Dog Toxicity Studies Rodent (Rat) Toxicity Studies Determine LD 10 on Dx1 & Dx5 Schedules Assess safety of 1/10 LD 10 Determine DLTs on Dx1 & Dx5 Schedules.

T&PB DRUG EVALUATION PHILOSOPHY Agent-Directed Studies Pharmacologically (PK/PD) - Guided Integrate With Preclinical Efficacy Data & the Proposed Clinical Protocol Rational Evaluation of Role of Schedule Dependence, Pharmacodynamics, Pharmacokinetics & Metabolism in the Development of Toxicity Relate Drug Levels and/or AUC (Plasma &/or Tissue), Biomarkers to Safety and to Occurrence & Severity of Toxicity Extrapolate Toxic Effects Across Species

AGENT-DIRECTED versus STANDARD PROTOCOL DRUG DEVELOPMENT Greater Scientific Basis for Development Permits Greater Flexibility Data Rich IND Submission to Support Phase I Preclinical Potential ….. Less Expensive Permits PK/PD-Guided Dose Escalation in Phase I Optimal Schedule ….. Greater Chance of Success? Patients ….. Greater Chance of Effective Therapy?

OBJECTIVES OF PRECLINICAL PHARMACOLOGY STUDIES FOR ANTI-NEOPLASTIC DRUGS Development of Sensitive Analytical Methods for Drugs in Biological Fluids & Tissues Determine In Vitro Stability and Protein Binding Determine Pharmacokinetics in Various Species Identification and Analysis of Metabolites Define Optimal Dose Schedule and Blood Sampling Times Define C P and/or AUC with Efficacy, Safety & Toxicity Analog Evaluation - Determine Optimal Development Candidate

 9-AC:Suspension72 Hr civ  Dolastatin 10: High C P MAX Efficacy  Penclomedine:High C P MAX Neurotoxicity C P < Threshold No Neurotoxicity  Isis 5320:High C P MAX BP , APTT , Bb  C P < Threshold No Toxic Effects  8-Cl-c-AMP:civ  Cl TB,  C P SS KEY PHARMACOLOGY CONTRIBUTIONS TO DRUG DEVELOPMENT

OBJECTIVES OF PRECLINICAL TOXICOLOGY STUDIES FOR ANTI-NEOPLASTIC DRUGS DETERMINE IN APPROPRIATE ANIMAL MODELS: The Maximum Tolerated Dose ( MTD ) Dose Limiting Toxicities ( DLT ) Schedule-Dependent Toxicity Reversibility of Adverse Effects A Safe Clinical Starting Dose

ADDITIONAL AGENT-DIRECTED TOXICOLOGY STUDY REQUIREMENTS Attain Efficacious Drug Levels in Plasma In Vivo Correlate Drug Plasma Levels and/or AUC with Toxicity and Safety Across Species Ameliorate Toxicity by Change in Route/Schedule Compare Toxicity with Accepted Clinical Agents as Necessary

SCHEDULE and ROUTE versus TOXICITY Pyrazoloacridine:Bolus ivNeurotoxicity 1 Hr civBone Marrow Penclomedine:Bolus ivNeurotoxicity 1 Hr Dx5BM (& Neuro) 5 Hr civNeuro & Death OralBM O 6 –Benzylguanine:BolusCNS, HR  InfusionNeutrophilia

DEVELOPMENT EXAMPLE: 9-AMINO-20[S]CAMPTOTHECIN (NSC ) [ Topoisomerase I Inhibitor ] *

9-AMINO-20[S]CAMPTOTHECIN (NSC ): PRECLINICAL EFFICACY & PK RESULTS EFFICACY Best:Rx sc, suspension, q4Dx8 Good:Rx sc, solution, Dx32 None:Rx sc, solution, q4Dx8 PHARMACOKINETICS iv, Solution:C P Max 11.8 µM, t ½ 1.38 hr sc, Solution:C P Max 1.95 µM, t ½ 1.58 hr sc, Suspension:C P Max 0.25 µM, t ½ 17.5 hr

9-AMINO-20[S]CAMPTOTHECIN (NSC ): PRECLINICAL PK & TOXICOLOGY STUDIES Mice: Pharmacokinetics - iv and sc  Repeated (q4Dx3) sc Dose Toxicity Study Rats: Pharmacokinetics - Bolus iv  72 Hr civ IND-Directed Toxicity Study Dogs: PK/Dose RF Study - Bolus iv  48 Hr civ Dose RF Toxicity Study  72 Hr civ Dose RF Toxicity Study  72 Hr civ IND-Directed Toxicity Study In Vitro:Murine, Canine, Human CFU GM

9-AMINO-20[S]CAMPTOTHECIN (NSC ): IN VITRO BONE MARROW DATA                     DRUG CONCENTRATION (nM) CFU-GM - % INHIBITION CANINE HUMAN MURINE   

9-AMINO[20S]CAMPTOTHECIN (NSC ): IN VITRO & IN VIVO TOXICITY DATA

9-AMINO[20S]CAMPTOTHECIN (NSC ): DEVELOPMENT CONCLUSIONS Bone Marrow and GI Toxicity are Dose Limiting in Mice, Rats and Dogs; and Should be in Man. Dogs are the Most Sensitive Species. In Vitro Bone Marrow Data Predicts that Man will be as Sensitive as the Dog. The MTD in Man & Dog Should be Comparable. 9-AC Lactone Plasma Levels and AUC Required for Efficacy in the Mouse are Not Achievable in the Dog.  Thus, 9-AC Should not be Effective in Man.

9-AMINO-20[S]CAMPTOTHECIN (NSC ): CORRELATION OF EFFICACY WITH TOXICITY & PHARMACOKINETICS

ACKNOWLEDGEMENTS T&PB Contractors Pharmacology Mayo Foundation Ohio State University Southern Research Univ Alabama Univ Pittsburgh Univ Texas - MDA Toxicology Battelle Memorial IITRI Southern Research SRI International Univ Illinois, Chicago Pathology Assoc.

ACKNOWLEDGEMENTS T&PB Staff PK: Joseph M. Covey, Ph.D. PK: Julie K Rhie, R.Ph., Ph.D. Tox: Susan J. Donohue, Ph.D. Tox: Elizabeth R. Glaze, Ph.D. Tox: Karen M. Schweikart, Ph.D. Tox: Adaline C. Smith, Ph.D., DABT Sec: Victoria Cordelli

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EORTC MINIMUM REQUIREMENTS FOR THE TOXICOLOGY OF A NEW CYTOSTATIC AGENT FOR PHASE I TRIALS Dx1 ip Mouse Lethality Study x NA Dx1 iv Mouse Lethality Study x x Dx1 Toxicity Study in Mice x NA Detailed Toxicity in Mice (Clin Prot) NA x Multiple Dose ip Toxicity Study in Mice x NA Toxicity Check in Rats at Clinical Dose x NA Toxicity Study in Rats (Clin Prot) NA x Limited PK Study in Mice (AUC at MTD) NA x