IND-Enabling Studies

What the IND-enabling package must establish

Under 21 CFR 312.23(a)(8), an IND must include “adequate information about pharmacological and toxicological studies of the drug involving laboratory animals or in vitro studies on the basis of which the sponsor has concluded that it is reasonably safe to conduct the proposed clinical investigations.” ICH M3(R2) is the international framework FDA and other ICH regulators use to define what “adequate” means in practice, scaling the required nonclinical package to the intended clinical trial’s duration, dose, and patient population rather than requiring the full nonclinical program up front.

The core components of a typical small-molecule IND-enabling package are:

• Repeat-dose toxicology in two species (typically one rodent, one non-rodent), of a duration that must generally equal or exceed the intended duration of the planned clinical dosing, conducted under Good Laboratory Practice (GLP) per 21 CFR Part 58 for pivotal studies.
• Safety pharmacology core battery (ICH S7A) — assessing effects on the cardiovascular, central nervous, and respiratory systems, the three organ systems considered most likely to produce acute, life-threatening effects if adversely affected.
• Genotoxicity battery (ICH S2(R1)) — in vitro and in vivo assays assessing the compound’s potential to damage genetic material, generally required before first-in-human dosing for most drug classes.
• Pharmacokinetics, toxicokinetics, and ADME (absorption, distribution, metabolism, excretion) studies (ICH S3A/S3B) — characterizing how the compound is handled in animal models, used together with the toxicology findings to translate an animal no-observed-adverse-effect level (NOAEL) into a proposed human starting dose.

The specific mix and depth of studies varies by drug class and intended indication — ICH S9 provides a scaled-back nonclinical package for oncology drugs intended for patients with advanced cancer, for example, reflecting a different risk-benefit calculus than a first-in-human study in healthy volunteers. A sponsor’s Pre-IND meeting with FDA — optional but common — is often used specifically to confirm that a proposed nonclinical package will be considered adequate before the sponsor commits the time and cost to running it.

GLP compliance and why it matters for IND timing

21 CFR 312.23(a)(8)(iii) requires that, for each nonclinical laboratory study subject to Part 58, the IND include a statement that the study was conducted in compliance with GLP regulations, or a brief statement of the reason for any noncompliance. FDA does not treat non-GLP data as an automatic rejection, but pivotal safety/toxicology studies conducted outside GLP are a well-recognized source of IND deficiency and clinical hold risk, because GLP’s Study Director and independent Quality Assurance Unit requirements exist specifically to give FDA confidence in the data’s integrity. This is one of the most common practical failure points for academic and early-stage sponsors building an IND-enabling package: running pivotal toxicology work at a non-GLP academic facility, then discovering during FDA’s 30-day review that the data cannot support the safety conclusion as submitted.

Timeline and resourcing

Because the full package — sourcing/synthesizing sufficient test article, running multi-week to multi-month GLP toxicology studies, generating and interpreting the safety pharmacology and genotoxicity batteries, and compiling the pharmacology/toxicology IND section — typically takes many months to run in sequence or parallel, IND-enabling studies represent one of the longest and most resource-intensive stretches of preclinical drug development. For sponsors without in-house toxicology capacity, options include contract research organizations (CROs) that specialize in GLP nonclinical work, and, for qualifying academic investigators, no-cost translational support such as NIH NCATS’ Bridging Interventional Development Gaps (BrIDGs) program, which provides access to IND-enabling development services including GLP toxicology and manufacturing support.

Related terms

See CASRAI’s entries on Investigational New Drug (IND) for the submission and FDA review process these studies feed into, Good Laboratory Practice (GLP) for the quality-system requirements governing pivotal nonclinical safety studies, and CASRAI’s Good Manufacturing Practice (GMP) guide for the parallel manufacturing-quality requirements that apply to producing the investigational drug supply used in these studies and in the first-in-human trial itself.