Unveiling changes in the landscape of patient populations in cancer early drug development

Healthy Volunteer Studies in the Development of Anticancer Drugs with Genotoxic Findings

Background

Recent scientific advances in cancer research have led to the development of immunomodulatory and molecularly targeted drugs with better safety profiles than chemotherapeutics, which makes it possible to include healthy volunteers (HVs) in clinical trials. In this study, we aimed to identify the number of marketing authorization applications (MAAs) that enrolled HVs in a clinical trial and to identify the number of anticancer drugs that were given to HVs despite a positive genotoxic finding. In addition, we evaluated the dose of anticancer drugs administered to HVs and the justification for proceeding with HV studies despite a positive genotoxic finding.

Methods

Publicly available information from the European Medicines Agency (EMA) website was used for this study. Anticancer drugs were identified using the human medicines highlights published by EMA between January 2010 and December 2019. EPARs were used to collect general information of the anticancer drugs, details on genotoxicity studies, and the enrollment of HVs in clinical trials.

Results

We identified 71 MAAs for small molecule anticancer drugs with a positive or negative CHMP opinion in the EU. Forty-eight anticancer drugs were studied in HVs, of which 12 anticancer drugs were administered to HVs despite positive genotoxic findings in the standard battery. Systematic and extensive genetic toxicology screening demonstrated the absence of genotoxic risks to the cell system.

Conclusion

We showed that despite a positive genotoxic finding, comprehensive genetic toxicology testing demonstrated the absence of risks to the cell system at the human exposure dose. Therefore, these anticancer drugs posed no harm to HVs.

New clinical trial designs in the era of precision medicine

Cancer treatment has made significant strides towards the promise of personalized medicine. Recent scientific advances have shown that there are numerous genetic deregulations that are common in multiple cancer types, raising the possibility of developing drugs targeting those deregulations irrespective of the tumour type. Precision Cancer Medicine (PCM) was born out of accumulated evidence matching targeted agents with these tumour molecular deregulations. At the same time, the therapeutic armamentarium is rapidly increasing and the number of new drugs (including immune-oncology agents) entering drug development continues to rise. These factors, added to strong collaboration with regulatory agencies, which have approved novel agents based on data obtained from phase 1/2 trials, have led to unprecedented evolution in the design of early-stage clinical trials. Currently, we have seen rapid phase 1 dose-escalation trials followed by remarkably large expansion cohorts, and are witnessing the emergence of new trials, such as adaptive studies with basket and umbrella designs aimed at optimizing the biomarker-drug co-development process. Alongside the growing complexity of these clinical trials, new frameworks for stronger and faster collaboration between all stakeholders in drug development, including academic institutions and frameworks, clinicians, pharma companies and regulatory agencies, have been established. In this review article, we describe the main challenges and opportunities that these new trial designs may provide for a more efficient drug development process, which may ultimately help ensure that PCM becomes a reality for patients.

Reviewing the role of healthy volunteer studies in drug development

BACKGROUND

With the exception of genotoxic oncology drugs, first-in-human, Phase 1 clinical studies of investigational drugs have traditionally been conducted in healthy volunteers (HVs). The primary goal of these studies is to investigate the pharmacokinetics and pharmacodynamics of a novel drug candidate, determine appropriate dosing, and document safety and tolerability.

MAIN BODY

When tailored to specific study objectives, HV studies are beneficial to manufacturers and patients alike and can be applied to both non-oncology and oncology drug development. Enrollment of HVs not only increases study accrual rates for dose-escalation studies but also alleviates the ethical concern of enrolling patients with disease in a short-term study at subtherapeutic doses when other studies (e.g. Phase 2 or Phase 3 studies) may be more appropriate for the patient. The use of HVs in non-oncology Phase 1 clinical trials is relatively safe but nonetheless poses ethical challenges because of the potential risks to which HVs are exposed. In general, most adverse events associated with non-oncology drugs are mild in severity, and serious adverse events are rare, but examples of severe toxicity have been reported. The use of HVs in the clinical development of oncology drugs is more limited but is nonetheless useful for evaluating clinical pharmacology and establishing an appropriate starting dose for studies in cancer patients. During the development of oncology drugs, clinical pharmacology studies in HVs have been used to assess pharmacokinetics, drug metabolism, food effects, potential drug-drug interactions, effects of hepatic and renal impairment, and other pharmacologic parameters vital for clinical decision-making in oncology. Studies in HVs are also being used to evaluate biosimilars versus established anticancer biologic agents.

CONCLUSION

A thorough assessment of toxicity and pharmacology throughout the drug development process is critical to ensure the safety of HVs. With the appropriate safeguards, HVs will continue to play an important role in future drug development.