What is an IND application? The modules that matter and where programs stall

An Investigational New Drug application (IND) is the submission under 21 CFR Part 312 that allows a sponsor to ship an unapproved drug across state lines and dose it in people. FDA reviews it for 30 days; if no clinical hold is issued, the trial may begin. In my experience, programs stall on manufacturing controls, toxicology gaps, and weak starting-dose justification.

What is an IND and what does the 30-day clock actually do?

Federal law prohibits shipping an unapproved drug across state lines, and the IND is the exemption that makes clinical testing legal. FDA recognizes investigator, emergency use, and treatment INDs [5]; this article concerns the commercial sponsor IND that opens a first-in-human trial. The IND goes into effect 30 days after FDA receives it unless FDA imposes a clinical hold [1]. FDA does not approve an IND. It lets the study proceed or stops it.

A hold is recoverable, but rarely quick. FDA must send a written explanation within 30 days of imposing it. The sponsor then submits a complete response, and FDA has 30 calendar days to say whether the hold is lifted [6]. Across 33 cell and gene therapy holds announced from 2020 through 2022, the average time to resolution was 6.2 months [7].

How is an IND organized, and which modules carry the review?

The content list sits in 21 CFR 312.23: a cover sheet on Form FDA 1571, a table of contents, an introductory statement and general investigational plan, the investigator's brochure, protocols, chemistry, manufacturing, and controls (CMC) information, pharmacology and toxicology information, and previous human experience [8]. The folder structure comes from the ICH Common Technical Document (CTD), whose modules FDA's M4 guidance describes [9]. Since May 5, 2018, commercial INDs must be filed electronically in eCTD format [3].

What do reviewers look for in the CMC module?

The data put CMC near the top of the risk list. In FDA's pilot of fiscal year 2013 submissions, CMC was the most frequent reason for hold, ahead of clinical and toxicology [2]. In FDA's later review of oncology INDs, clinical deficiencies ranked first and pharmaceutical quality second [4].

The reviewer's core question is simple: is the material you will inject into people the same material you tested in animals? Answering it takes analytical comparability between the toxicology lot and the clinical lot, a potency assay that measures the mechanism, and stability data covering the planned duration of dosing.

On the first-in-class biologic for a rare pediatric leukemia that I carried to IND acceptance, the CMC module took longer to assemble than any other. The honest limit is that a Phase 1 package will not be commercial grade, and FDA's Phase 1 content guidance scales expectations to the phase [10]. The mistake is presenting a thin package as final instead of stating what remains.

What nonclinical package does Module 4 need to clear?

ICH M3(R2) sets the baseline. Repeat-dose toxicity studies in two species, one non-rodent, lasting at least two weeks generally support a clinical trial of up to two weeks; longer trials need toxicity studies of at least equivalent duration [11]. For each study subject to Part 58, the IND must state that it was run under Good Laboratory Practice (GLP) or explain why not [8].

Biologics follow different logic. ICH S6(R1) requires relevant species, meaning species in which the drug is pharmacologically active because the receptor or epitope is expressed. Two relevant species are the norm, but one may suffice when only one can be identified or the biology is well understood. Studies in non-relevant species are called misleading and discouraged [12].

Programs stall here in three ways I see repeatedly: toxicology shorter than the protocol's dosing schedule, a rodent species that does not bind the target, and pivotal studies run non-GLP to save money. On the pediatric leukemia program, we settled species relevance with binding and functional data before the pre-IND meeting, not after.

How do you justify a first-in-human starting dose?

FDA's 2005 guidance gives the default algorithm for healthy volunteers. Identify the no-observed-adverse-effect level (NOAEL) in each species, convert it to a human equivalent dose by body surface area, choose the most appropriate species, and apply a safety factor with a default of 10 to reach the maximum recommended starting dose [13].

For agonists, immune modulators, and novel mechanisms, the NOAEL approach can overshoot. The EMA first-in-human guideline directs sponsors to estimate the minimal anticipated biological effect level (MABEL) from target binding, receptor occupancy, and pharmacodynamic data, and to anchor the starting dose to MABEL, the pharmacologically active dose, or NOAEL depending on uncertainty [14]. I present both calculations and state which governs. The tradeoff is real: a MABEL dose can be so low that escalation adds cohorts and cost.

Why does the investigator's brochure cause holds?

Under 21 CFR 312.23(a)(5) it must describe the drug substance and formulation, summarize animal and human pharmacology and toxicology, summarize pharmacokinetics and prior clinical safety, and describe anticipated risks and precautions [8]. A brochure that is misleading, erroneous, or materially incomplete is an explicit ground for a Phase 1 hold [6]. The common failure is a brochure drafted before final toxicology reports arrived. I freeze it last and cross-check every value against Module 4.

How often do INDs stall, and what does a pre-IND meeting change?

The base rate is lower than many founders fear. Of 1,410 initial INDs received by CDER in fiscal year 2013, 125 (8.9 percent) were placed on hold within 30 days, and more than half of those became active within a year [2]. In oncology, fewer than 10 percent went on hold or were withdrawn during the 30-day review, concentrated in first-in-human trials and less experienced sponsors [4].

The pre-IND meeting is a Type B meeting. FDA aims to respond to the request within 21 days and to hold the meeting within 60 calendar days of receiving it [15]. FDA's oncology analysis found that held and proceeding INDs had similar rates of pre-IND meetings, but the interval between meeting and submission was longer for INDs that went on hold [4]. The meeting helps when the questions are focused and the filing follows promptly.

On the pediatric leukemia biologic, I drafted sizable portions of the IND myself, which was accepted and Fast Track designation followed two months later. I credit the clean review to effective teamwork, high quality writing/data, and closing every pre-IND question before submission. An accepted IND does not validate the drug. It validates the plan to test it safely.

This article is part of the Life Sciences Consulting practice at Hamilton Atlas Group — see the full capability list there.

References

1. U.S. Government Publishing Office. 21 CFR 312.40 General requirements for use of an investigational new drug in a clinical investigation. Code of Federal Regulations, 2024.
2. Lapteva L, Pariser AR. Investigational New Drug applications: a 1-year pilot study on rates and reasons for clinical hold. Journal of Investigative Medicine. 2016;64(2):376-382.
3. U.S. Food and Drug Administration. Providing Regulatory Submissions in Electronic Format -- Certain Human Pharmaceutical Product Applications and Related Submissions Using the eCTD Specifications Guidance for Industry. FDA, 2024.
4. Manning ML, Thompson MD, Saber H, et al. An FDA analysis of clinical hold deficiencies affecting investigational new drug applications for oncology products. Regulatory Toxicology and Pharmacology. 2020;110:104511.
5. U.S. Food and Drug Administration. Investigational New Drug Application (IND). FDA, 2026.
6. U.S. Government Publishing Office. 21 CFR 312.42 Clinical holds and requests for modification. Code of Federal Regulations, 2024.
7. Wills CA, Drago D, Pietrusko RG. Clinical holds for cell and gene therapy trials: Risks, impact, and lessons learned. Molecular Therapy Methods & Clinical Development. 2023;31:101125.
8. U.S. Government Publishing Office. 21 CFR 312.23 IND content and format. Code of Federal Regulations, 2024.
9. U.S. Food and Drug Administration. M4 Organization of the Common Technical Document for the Registration of Pharmaceuticals for Human Use Guidance for Industry. FDA, 2017.
10. U.S. Food and Drug Administration. Content and Format of Investigational New Drug Applications (INDs) for Phase 1 Studies of Drugs, Including Well-Characterized, Therapeutic, Biotechnology-derived Products. FDA, 1995.
11. International Council for Harmonisation. Guidance on Nonclinical Safety Studies for the Conduct of Human Clinical Trials and Marketing Authorization for Pharmaceuticals M3(R2). ICH, 2009.
12. International Council for Harmonisation. Preclinical Safety Evaluation of Biotechnology-Derived Pharmaceuticals S6(R1). ICH, 2011.
13. U.S. Food and Drug Administration. Estimating the Maximum Safe Starting Dose in Initial Clinical Trials for Therapeutics in Adult Healthy Volunteers. FDA, 2005.
14. European Medicines Agency. Strategies to identify and mitigate risks for first-in-human and early clinical trials with investigational medicinal products - Scientific guideline. EMA, 2017.
15. U.S. Food and Drug Administration. Formal Meetings Between the FDA and Sponsors or Applicants of PDUFA Products. FDA, 2026.