Phase 0 Clinical Trials
Sponsored by Center for Cancer Research National Cancer Institute Slides courtesy of: James, Doroshow, MD Director, Division of Cancer Treatment and Diagnosis National Cancer Institute
What is a Phase 0 trial?
First-In-Human trial:
Limited number of subjects (10-12) Very limited drug exposure
Low, supposedly non-toxic doses Limited duration of dosing ( 7 days) One course
No therapeutic (or diagnostic) intent Conducted prior to traditional Phase 1 dose escalation, safety, and tolerance studies that ordinarily initiate a clinical drug development program Can be initiated with a less extensive pre-clinical data than traditional Phase 1 trials
Also referred to as:
Pre-phase 1 trial Pilot study Exploratory Investigational New Drug (IND) study
Goals of a Phase 0 Trial
Generate data to: Inform subsequent development of the agent Enhance efficiency of subsequent development of the agent Increase chance of success of subsequent development of the agent
Why are Phase 0 Oncology Trials Needed?
Theres a need to improve the efficiency and success rate of clinical trials
Most drugs in clinical development do not make it to registration Failure rate is higher for oncology drugs than other indications Most drugs that fail, fail in late stages of clinical development
Late failure (due to bad drug or target) means wasted resources, including patients
Success Rates from First-in-Man to Registration
5%
Data from 10 biggest drug companies from 1991-2000
Kola And Landis; Nature Reviews Drug Discovery 2004
Most drugs fail in late stages of developmentparticularly in Oncology
Rates of success for compounds entering first in man that progress to subsequent phase
70% of oncology drugs that enter Phase 2 fail to enter Phase 3
All indications
59% of oncology drugs that enter Phase 3 fail
Risk of failure may be higher for novel targeted agents
Kola & Landis; Nature Reviews Drug Discovery 2004
Why drugs fail
Unfavorable PK currently plays less of a role compared to early 1990s Lack of efficacy continues to play a major role Lack of predictive animal models
Kola & Landis; Nature Reviews Drug Discovery 2004, Ma & Zemmel; Nature Reviews Drug Discovery 2002
How can Phase 0 trials improve efficiency and success of subsequent trials?
Eliminate an agent very early in clinical development because of poor PD (pharmacodynamic) or PK (pharmacokinetic) properties
E.g., lack of target effect, poor bioavailability, rapid clearance
Inform subsequent trials by:
Validating a PD assay for assessing target modulation Developing a reliable SOP for tissue acquisition, handling, and processing Determining dose and time course that yields a required target effect Intensively evaluating PK, providing a closer approximation to a safe, but potentially effective starting dose and support for limited sampling in subsequent trials
Phase 0 Trial Outcomes
Determine whether a mechanism of action defined in non-clinical models can be observed in humans (e.g., binds to or inhibits its alleged target) Provide human PK/PD data for an agent prior to definitive Phase 1-2 testing
Refine biomarker assay using human tumor tissue and/or surrogate tissue
Phase 0 Trial Outcomes
Evaluate human PD and/or PK (e.g., bioavailability) of two or more analogs directed at the same target and possessing practically the same properties in vitro and in animal models, helping to select the most promising candidate for further development Evaluate in humans an agents biodistribution, binding characteristics and target effects using micro-dosing and a variety of novel imaging technologies
Prioritizing Candidate Agents for Phase 0 Study
PD endpoint is critical to development (need credentialed PD marker or drug target) Pre-clinical data show a wide therapeutic window PD modulation expected at low doses and short durations of exposure (e.g. 7 days) Drug target effect likely to be determined with a relatively small sample size (10-15 patients) Need for bioavailability or PD data to select best candidate among two or more analogues
What does a Phase 0 trial involve
Pre-clinical: Studies in animal models prior to initiating Phase 0 trial to:
Validate PD biomarker assay Simulate human tissue acquisition, handling and processing Demonstrate drug effect on target or biomarker Determine PK-PD relationships Evaluate drug biodistribution and binding using imaging technologies
Validate PD assay methodology using human tumor samples or surrogate tissue (e.g., PBMCs) prior to Phase 0 trial
What does a Phase 0 trial involve
Pre-Clinical Clinical
Interrogating and validating target or biomarker assay in human tumor biopsies and/or surrogate tissue
Reproducibility across technicians, labs Variables/conditions standards, temperature, storage, dilution effects (linearity?) Coefficient of variability (needs to be tight)
Developing an SOP for human tissue acquisition, handling and processing Demonstrating drug target or biomarker effect Determining PK-PD relationships Drug biodistribution and binding using novel imaging technologies Innovative statistical designs
Limited sample size PD and PK as primary endpoints, rather than MTD
Phase 0 Statistical Issues
Limit sample size to 6-15 patients, generally Define primary endpoint(s) prospectively If possible, obtain a measure of intra-patient variability for the pre-treatment endpoint values Define thresholds (binomial) for declaring treatment effect on biomarker (efficacy) for an individual patient, for a given dose, based on both biological and statistical criteria (5% false +) Target a reasonable efficacy % threshold, across patients, at a dose level, for detection with high power (90%) Maintain a reasonable false positive rate (10%) across dose levels
Phase 0 Program: Logistical Considerations
Mechanism for selecting and prioritizing candidate agents Dedicated non-clinical PD assay development laboratory including non-clinical animal models Dedicated human tissue PD laboratory, capable of real-time analysis PK lab capable of real-time analysis
Clinical team with expertise in conduct of early phase trials
Phase 0 Program: Logistical Considerations
Efficiently integrated collaborations between the clinical research team and:
PK and PD laboratory scientists Biospecimen procurement and processing staff Interventional radiologists Special imaging and nuclear medicine staff Statisticians Regulatory bodies Drug sponsors Project Managers
Willing patient participants
Phase 0 Program: Ethical Considerations
Potential barriers to enrollment
No therapeutic intent or chance of benefit Pre- and post-treatment tissue biopsies Delay or exclusion from other trials or therapies
External concerns about ethics and availability of patients for study Institutional Ethics committee review and input Informed Consent Process
Need to clearly explain the rationale for the study Need to define the limited treatment and follow up period Need to clearly state that there is absolutely no anticipated clinical benefit to the participant
Promising candidate drugs are identified and prioritized early Less promising drugs are eliminated early in development Efficiency and success rate of Phase 1-2 trials are improved Less drugs fail in late stages of clinical development Higher proportion of drugs in clinical development make it to registration and FDA approval Resources shifted to Phase 0 conserve resources in subsequent development, including highly valued patient participation
Some Measures of Success Phase 0
References
Kola, I. & Landis, J. (2004). OPINION: Can the pharmaceutical industry reduce attrition rates? Nature Reviews Drug Discovery, 3 , 711-716. Ma, P. & Zemmel, R. (2002). Value of novelty Nature Reviews Drug Discovery, 1 (8) , 571-572.
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