Clearing the Path for New Uses for Generic Drugs
The labeling-only 505(b)(2) NDA pathway for non-manufacturers to seek FDA approval
Repurposing generic drugs as new treatments for life-threatening diseases is an exciting yet largely overlooked opportunity due to a lack of market-driven incentives. The low profit margins for generic drugs mean that pharmaceutical companies rarely invest in research, regulatory efforts, and marketing for new uses. Nonprofit organizations and other non-commercial non-manufacturers are increasing efforts to repurpose widely available generic drugs and rapidly expand affordable treatment options for patients. However, these non-manufacturers find it difficult to obtain regulatory approval in the U.S. They face significant challenges in using the existing approval pathways, specifically in: 1) providing the FDA with required chemistry, manufacturing, and controls (CMC) data, 2) providing the FDA with product samples, and 3) conducting post-marketing surveillance. Without a straightforward path for approval and updating drug labeling, non-manufacturers have relied on off-label use of repurposed drugs to drive uptake. This practice results in outdated labeling for generics and hinders widespread clinical adoption, limiting patient access to these potentially life-saving treatments.
To encourage greater adoption of generic drugs in clinical practice – that is, to encourage the repurposing of these drugs – the FDA should implement a dedicated regulatory pathway for non-manufacturers to seek approval of new indications for repurposed generic drugs. A potential solution is an extension of the existing 505(b)(2) new drug application (NDA) approval pathway. This extension, the “labeling-only” 505(b)(2) NDA, would be a dedicated pathway for non-manufacturers to seek FDA approval of new indications for well-established small molecule drugs when multiple generic products are already available. The labeling-only 505(b)(2) pathway would be applicable for repurposing drugs for any disease. Creating a regulatory pathway for non-manufacturers would unlock access to innovative therapies and enable the public to benefit from the enormous potential of low-cost generic drugs.
Challenge and Opportunity
The opportunity for generic drug repurposing
On-patent, branded drugs are often unaffordable for Americans. Due to the high cost of care, 42% of patients in the U.S. exhaust their life savings within two years of a cancer diagnosis. Generic drug repurposing – the process of finding new uses for FDA-approved generic drugs – is a major opportunity to quickly create low-cost and accessible treatment options for many diseases. In oncology, hundreds of generic drugs approved for non-cancer uses have been tested as cancer treatments in published preclinical and clinical studies.
The untapped potential for generic drug repurposing in cancer and other diseases is not being realized because of the lack of market incentives. Pharmaceutical companies are primarily focused on de novo drug development to create new molecular and chemical entities. Typically, pharmaceutical companies will invest in repurposing only when the drugs are protected by patents or statutory market exclusivities, or when modification to the drugs can create new patent protection or exclusivities (e.g., through new formulations, dosage forms, or routes of administration). Once patents and exclusivities expire, the introduction of generic drugs creates competition in the marketplace. Generics can be up to 80-85% less expensive than their branded counterparts, driving down overall drug prices. The steep decline in prices means that pharmaceutical companies have little motivation to invest in research and marketing for new uses of off-patent drugs, and this loss of interest often starts in the years preceding generic entry.
In theory, pharmaceutical companies could repurpose generics without changing the drugs and apply for method-of-use patents, which should provide exclusivity for new indications and the potential for higher pricing. However, due to substitution of generic drugs at the pharmacy level, method-of-use patents are of little to no practical value when there are already therapeutically equivalent products on the market. Pharmacists can dispense a generic version instead of the patent-protected drug product, even if the substituted generic does not have the specific indication in its labeling. Currently, nearly all U.S. states permit substitution by the pharmacy, and over a third have regulations that require generic substitution when available.
Nonprofits like Reboot Rx and other non-commercial non-manufacturers are therefore stepping in to advance the use of repurposed generic drugs across many diseases. Non-manufacturers, which do not manufacture or distribute drugs, aim to ensure there is substantial evidence for new indications of generic drugs and then advocate for their clinical use. Regulatory approval would accelerate adoption. However, even with substantial evidence to support regulatory review, non-manufacturers find it difficult or impossible to seek approval for new indications of generic drugs. There is no straightforward pathway to do so within the current U.S. regulatory framework without offering a specific, manufactured version of the drug. This challenge is not unique to the U.S.; recent efforts in the European Union (EU) have sought to address the regulatory gap. In the 2023 EU reform of pharmaceutical legislation, Article 48 is currently under review by the European Parliament as a potential solution to allow nonprofit entities to spearhead submissions for the approval of new indications for authorized medicinal products with the European Medicines Agency. To maximize the patient impact of generic drugs in America, non-manufacturers should be able to drive updates to FDA drug labeling, enabling widespread clinical adoption of repurposed drugs in a formal, predictable, and systematic manner.
The importance of FDA approval
Drugs that are FDA-approved can be prescribed for any indication not listed on the product labeling, often referred to as “off-label use”. Since non-manufacturers face significant challenges pursuing regulatory approval for new indications, they often must rely on advocating for off-label use of repurposed drugs.
While off-label use is widely accepted and helpful for specific circumstances, there are significant advantages to having FDA approval of new drug indications included in labeling. FDA drug labeling is intended to contain up-to-date information about drug products and ensures that the necessary conditions of use (including dosing, warnings, and precautions) are communicated for the specific indications. It is the primary authoritative source for making informed treatment decisions and is heavily valued by the medical community. Approval may increase the likelihood of uptake by clinical guidelines, pathways systems, and healthcare payers. Indications with FDA approval may generate greater awareness of the treatment options, leading to a broader and more rapid impact on clinical practice.
Clinical practice guidelines are often the leading authority for prescribers and patients regarding off-label use. In oncology, for example, the National Comprehensive Cancer Network (NCCN) Guidelines are commonly used guidelines that include many off-label uses. However, guidelines do not exist for every disease and medical specialty, which can make it more difficult to gain acceptance for off-label uses. The Centers for Medicare and Medicaid Services (CMS) policy routinely covers off-label drug uses if they are listed in certain compendia. The NCCN Compendia, which is based on the NCCN Guidelines, is the only accepted compendium that is disease-specific.
Off-label use requires more effort from individual prescribers and patients to independently evaluate new drug data, thereby slowing uptake of the treatments. This can be especially difficult for community-based physicians, who need to remain up-to-date on new treatment options across many diseases. Off-label prescribing can also introduce medico-legal risks, such as malpractice. These burdens and risks limit off-label prescribing, even when there is supportive evidence for the new uses.
As new uses for generic drugs are discovered, it is crucial to update the labeling to ensure alignment with current clinical practice. Outdated generic drug labeling means that prescribers and patients may not have access to all the necessary information to understand the full risk-benefit profile. Americans deserve to have access to all effective treatment options – especially low-cost and widely available generic drugs that could help mitigate the financial toxicity and health inequities faced by many patients. For the public benefit, the FDA should support approaches that remove regulatory barriers for non-manufacturers and modernize drug labeling.
Existing pathways for manufacturers to obtain FDA approval
The current FDA approval system is based on the idea that sponsors have discrete physical drug products. Traditionally, sponsors seeking FDA approval are pharmaceutical companies or drug manufacturers that intend to produce (or contract for production), distribute, and sell the finished drug product. For the purposes of FDA regulation, “drug” refers to a substance intended for use in the treatment or prevention of disease; “drug product” is the final dosage form that contains a drug substance and inactive ingredients made and sold by a specific manufacturer. One drug can be present on the market in multiple drug products. In the current regulatory framework, drug products are approved through one of the following:
- 505(b)(1) NDA: New drug products, including new molecular entities, are first submitted for FDA review through the 505(b)(1) new drug application (NDA) pathway. In this pathway, the sponsor either generates all necessary clinical data or owns the right of reference to the clinical data needed to support the NDA. FDA approval of an NDA establishes a reference listed drug (RLD), based on the FDA’s determinations of safety and effectiveness for the drug.
- 505(b)(2) NDA: For new drug products or formulations utilizing or related to previously approved drugs or drug substances, the 505(b)(2) NDA pathway offers a streamlined alternative to the 505(b)(1) NDA. By allowing the sponsor to reference the FDA’s findings of safety and effectiveness for previously approved drugs and published literature, the sponsor can submit data they do not own or for which they do not have the right of reference, once any exclusivities expire.
- ANDA: Generic drug equivalents are approved through the 505(j) abbreviated NDA (ANDA) pathway. The RLD serves as the standard that other manufacturers may reference when seeking approval for generic versions of the drug. Upon approval, ANDA products receive a therapeutic equivalence designation in the FDA’s Orange Book, indicating the generic drug products are interchangeable for and substitutable with the RLD.
- BLA: Biological products are approved through the biologics license application (BLA). There is currently no provision analogous to section 505(b)(2) under the law governing the approval of biological products. While the FDA is authorized to approve biosimilars, including interchangeable biosimilars akin to generics, no current pathway permits the addition of new indications for use to a biosimilar product short of submitting a complete, original BLA with full preclinical and clinical data. Our proposed regulatory pathway is relevant for small molecule drugs and would not be applicable to biological products under current law.
Manufacturers can add new indications to their approved labeling without modifying the drug product through existing pathways. With supportive clinical evidence for the new indication, the NDA holder can file a supplemental NDA (sNDA), while an ANDA holder may submit a 505(b)(2) NDA as a supplement to their existing ANDA. As previously discussed, the drug product will likely be subject to pharmacy-level substitution with any available therapeutically equivalent generic. The marketing exclusivities that sponsors may receive from the FDA do not protect against this substitution. Therefore, these pathways are rarely, if ever, used by pharmaceutical companies when there are already multiple generic manufacturers of the product.
Challenges for non-manufacturers in using existing pathways
Since manufacturers are not incentivized to seek regulatory approval for new indications, labeling changes are more likely to happen if driven by non-manufacturers. Yet non-manufacturers face significant challenges in utilizing the existing regulatory pathways. Sponsors must submit the following information for all NDAs for the FDA’s review: 1) clinical and nonclinical data on the safety and effectiveness of the drug for the proposed indication; 2) the proposed labeling; and 3) chemistry, manufacturing, and controls (CMC) data describing the methods of manufacturing and the controls to maintain the drug product’s quality.
To submit and maintain NDAs, non-manufacturer sponsors would need to address the following challenges:
- Providing the FDA with required CMC data. NDA sponsors must provide CMC data for FDA review. Non-manufacturers would not produce physical drug products, and therefore they would not have information on the manufacturing process.
- Providing the FDA with product samples. If requested, NDA sponsors must have the drug products and other samples (e.g., drug substances or reference standards) available to support the FDA review process and must make available for inspection the facilities where the drug substances and drug products are manufactured. Non-manufacturers would not have physical drug products to provide as samples, the capabilities to produce them, or access to the facilities where they are made.
- Conducting post-marketing surveillance. Post-marketing responsibilities to maintain an NDA include conducting annual safety reporting and maintaining a toll-free number for the public to call with questions or concerns. Non-manufacturers, such as small nonprofits, may not have the bandwidth or resources to meet these requirements.
Within the current statutory framework, a non-manufacturer could sponsor a 505(b)(2) NDA to obtain approval of a new indication by partnering with a current manufacturer of the drug – either an NDA or ANDA holder. The manufacturer would help meet the technical requirements of the 505(b)(2) application that the non-manufacturer could not fulfill independently. Through this partnership, the non-manufacturer would acquire the CMC data and physical drug product samples from the manufacturer and rely on the manufacturer’s facilities to fulfill FDA inspection and quality requirements.
Once approved, the 505(b)(2) NDA would create a new drug product with indication-specific labeling, even though the product would be identical to an existing product under a previous NDA or ANDA. The 505(b)(2) NDA would then be tied to the specific manufacturer due to the use of their CMC data, and that manufacturer would be responsible for producing and distributing the drug product for the new indication.
As a practical matter, this pathway is rarely attainable. Manufacturers of marketed drug products, particularly generic drug manufacturers, lack the incentives needed to partner with non-manufacturers. Manufacturers may not want to provide their CMC data or samples because it may prompt FDA inspection of their facilities, require an update to their CMC information, or open the door to product liability risks. The existing incentive structure strongly discourages generic drug manufacturers from expending any additional resources on researching new uses or making any changes to their product labeling that would deviate from the original RLD product.
Plan of Action
To modernize drug labeling and enhance clinical adoption of generic drugs, the FDA should implement a dedicated regulatory pathway for non-manufacturers to seek approval of new indications for repurposed generic drugs. Ultimately, such a pathway would enable drug repurposing and be a crucial step toward equitable healthcare access for Americans. We propose a potential solution – a “labeling-only” 505(b)(2) NDA – as an extension of the existing 505(b)(2) approval pathway.
Overview of the proposed labeling-only 505(b)(2) NDA pathway
The labeling-only 505(b)(2) NDA would enable non-manufacturers to reference CMC information from previous FDA determinations and, when necessary, provide the FDA with samples of commercially available drug products. Through this approach, the new indication would not be tied to a specific drug product made by one manufacturer. There is no inherent necessity for a new indication of a generic drug to be exclusively linked to a single manufacturer or drug product when the FDA has already approved multiple therapeutically equivalent generic drugs. Any of these interchangeable drug products would be considered equally safe and effective for the new indication, and patients could receive any of these drug products due to pharmacy-level substitution.
We describe non-manufacturer repurposing sponsors as entities that intend to submit or reference clinical data through a labeling-only 505(b)(2) NDA. This pathway is designed to expand the FDA-approved labeling of generic drugs for new indications, including those that may already be considered the standard of care. Non-manufacturers do not have the means to independently produce or distribute drug products. Instead, they intend to show that there is substantial evidence to support the new use through FDA approval, and then advocate for the indication in clinical practice. This evidence may be based on their research or research performed by other entities, including clinical trials and real-world data analyses.
The labeling-only 505(b)(2) NDA pathway helps address the three major challenges non-manufacturers face in pursuing regulatory approval. Through this pathway, non-manufacturers would be able to:
- Reference the FDA’s previous determinations on CMC data. Currently, a 505(b)(2) NDA can reference the FDA’s previous determinations of safety and effectiveness for an approved drug product. For eligible generic drugs, the labeling-only 505(b)(2) NDA would build on this practice by allowing non-manufacturer sponsors to reference the FDA’s previous determinations on any NDA or ANDA that the manufacturing process and CMC data are adequate to meet regulatory standards.
- Provide the FDA with product samples using commercially available drug product samples. Currently, it is up to the discretion of the FDA whether or not to request samples in the review of an application. With the labeling-only 505(b)(2) NDA, non-manufacturers would provide the FDA with samples of commercially available products from generic manufacturers. Given that the FDA would have already evaluated the products and their bioequivalence to the RLD during the previous reviews, it is not expected that the FDA would need to re-examine the product at the level of requesting samples, except potentially to examine the packaging and physical presentation of the product for compatibility with the new indication and conditions of use. The facilities where the drugs are made would remain available for inspection, under the same terms and conditions as the existing, approved marketing applications.
- Manage post-marketing responsibilities. Since most post-marketing surveillance and adverse event reporting are drug product-specific, these obligations would continue to be the responsibility of the manufacturer of the physical drug product dispensed. With the labeling-only 505(b)(2) NDA, the non-manufacturer would not have product-specific obligations because they are not putting a new product into the marketplace. However, we anticipate the non-manufacturer would be responsible for the repurposed indication on their labeling, including but not limited to post-marketing surveillance as well as indication-specific adverse event reporting and reasonable follow-up.
Under the labeling-only 505(b)(2) NDA, the non-manufacturer sponsor would not introduce a new physical drug product into the market. The new labeling created by the approval would not expressly be associated with one specific product. The non-manufacturer’s labeling would refer to the drug by its established generic name. In that way, the non-manufacturer sponsor’s approval and labeling could be applicable to all equivalent versions of the drug product and would be available for patients to receive from their pharmacy in the same way that generic drugs are typically dispensed at the pharmacy. That is, with the benefit of pharmacy-level substitution, patients could receive any available, therapeutically equivalent drug products from any current manufacturer.
Eligibility criteria
We envision the users of this pathway to be non-manufacturers that conduct drug repurposing research for the public benefit, including organizations like nonprofits and patient advocacy groups. The FDA should implement and enforce additional guardrails on eligibility to ensure that sponsors operate in good faith and cannot otherwise meet traditional NDA requirements. This process may include pre-submission meetings and reviews. The labeling-only 505(b)(2) NDA should be held to the FDA’s standard level of rigor and scrutiny of safety and effectiveness for the proposed indication during the review process.
The labeling-only 505(b)(2) would only be suitable for well-established, commercially available small molecule generic drugs, which can be identified as:
- Drugs with a U.S. Pharmacopeia and National Formulary (USP-NF) monograph. The USP-NF monograph system ensures the uniformity of available products on the market by setting a consensus minimum standard of identity, strength, quality, and purity among all marketed versions of a drug. It is expressly recognized in the Federal Food, Drug, and Cosmetics Act (FDCA). The USP-NF strives to have substance and product monographs for all FDA-approved drugs. USP-NF monographs for generics are commonly available because the drugs have been on the market for a long time and are typically produced by multiple manufacturers. Drug products in the U.S. market must conform to the standards in the USP-NF, when available, to avoid possible charges of adulteration and misbranding.
By statute and regulation, the FDA already allows for NDAs and ANDAs to reference the USP-NF to satisfy some CMC requirements, such as for specifications of the drug substance. As an illustration of the acceptance of the USP-NF, clinical trial protocols requiring the use of background therapy or supportive care, as well as trials testing medical devices requiring the use of a drug product, often will specify that any available version of the drug product meeting USP-NF standards can be used. We propose that products without USP-NF monographs, including certain newer drugs and drugs with especially complicated manufacturing processes that are not conducive to standardization, would not be eligible for the labeling-only 505(b)(2) pathway.
- Drugs with multiple A-rated, therapeutically equivalent products in the FDA Orange Book. The FDA does not regulate which specific products are dispensed or substituted for a given drug prescription. The listing of therapeutic equivalents in the Orange Book facilitates the seamless replacement of drug products from different manufacturers in clinical practice. Therapeutically equivalent drug products: i) have demonstrated bioequivalence to the RLD; ii) have the same strength, dosage form, and route of administration as the RLD; and iii) are labeled for the same conditions of use as the RLD. Therapeutic equivalents that meet these criteria are designated “A-rated” in the Orange Book. A-rated drug products are substitutable for any other version of that A-rated drug product, including the RLD itself.
Implementation
The labeling-only 505(b)(2) NDA pathway could be implemented through an FDA guidance document interpreting the current statute and regulations or through legislation that clarifies the FDA’s existing authority. Guidance documents contain the FDA’s interpretation of a given policy on regulatory issues. The FDA’s Center for Drug Evaluation and Research (CDER) could issue new guidance that allows for interpretation of the existing statute, thereby officially authorizing previous FDA determinations of acceptable CMC data to be referenceable for eligible generic drugs and adjusting drug sample requirements. Alternatively, the labeling-only 505(b)(2) could be enacted by Congress through a statutory change by incorporation into FDCA, which is up for reauthorization through the Prescription Drug User Fee Act (PDUFA) in 2027, or other congressional acts as appropriate. FDA guidance would be a faster pathway to adoption, while statutory authorization would offer additional safeguards for the continuance of the pathway long term.
The labeling-only 505(b)(2) NDA pathway could be funded through user fees, which are established by PDUFA for the cost to file and maintain NDAs. However, many nonprofit sponsors would not be able to afford the same user fees as for-profit pharmaceutical manufacturers. Relevant statutes will likely need to be updated to create a different fee schema for non-manufacturers who use the labeling-only 505(b)(2) pathway. In a similar spirit to reducing barriers to maintaining up-to-date labeling, the 2017 PDUFA update waived the fee for submitting an sNDA, which is how an existing RLD holder would update their labeling with new indication information.
Conclusion
Patients need new and affordable treatment options for diseases that have a devastating societal impact, and repurposing generic drugs can help address this need. Nonprofits and other non-manufacturers are driving these efforts forward due to a lack of interest from pharmaceutical companies. As momentum gains for generic drug repurposing, the U.S. regulatory system needs a pathway for non-manufacturers to seek FDA approval of new indications for existing generic drugs. Our proposed labeling-only 505(b)(2) NDA would eliminate undue administrative burden, enabling non-manufacturers to pursue FDA approval of new indications. It would allow the FDA to provide the public with the most up-to-date drug labeling, improving the ability of patients and physicians to make informed treatment decisions. This dedicated pathway would increase the availability of effective treatment options while reducing costs for the American healthcare system.
This action-ready policy memo is part of Day One 2025 — our effort to bring forward bold policy ideas, grounded in science and evidence, that can tackle the country’s biggest challenges and bring us closer to the prosperous, equitable and safe future that we all hope for whoever takes office in 2025 and beyond.
The FDA does not have sufficient bandwidth or resources to meet the opportunity we have with repurposed generic drugs. To be the primary driver of labeling changes for repurposed generic drugs, the FDA would need to identify repurposing opportunities and also thoroughly compile and evaluate the safety and effectiveness data for the new indications. Project Renewal in FDA’s Oncology Center of Excellence is working with RLD holders to update the labeling of certain older oncology drugs where the outdated labeling does not reflect their current clinical use. The initial focus of Project Renewal is limited, and newly repurposed treatments are not included within its scope. For newly repurposed treatments, the FDA could evaluate the drugs and post to the Federal Register reports on their safety and effectiveness that could be referenced by manufacturers. However, this approach is burdensome as it would require a significant commitment of FDA resources. By introducing a motivated, third-party non-manufacturer as the primary driver for labeling changes, non-manufacturers can contribute expertise and resources to enable faster data evaluation for more drugs.
The pre-existing NDA sponsor could update their labeling to add the new indication through an sNDA that references the labeling-only 505(b)(2) NDA. ANDA holders would then be legally required to match their labeling to that of the RLD. The FDA should determine whether all current manufacturers would be required to update their labeling following approval of the new indication, and if so, the appropriate process.
Generic drugs play a vital role in the U.S. healthcare system by decreasing drug spending and increasing the accessibility of essential medicines. Generics account for 91% of prescriptions filled in the U.S. Expanding the market with generics for new indications could lead to short-term price increases above the inflation rate for off-patent branded and generic drugs in some unlikely circumstances. For example, if a new use for a generic drug substantially increases demand for the drug, there is a short-term risk that prices for the drug or potential substitutes could rise until manufacturers build more capacity to increase supply. To mitigate this risk, generic manufacturers could be notified about potential increases in demand so they can plan for increased production.
Generally, healthcare payers are not required to cover or reimburse for off-label uses of drugs. Unless a drug undergoes utilization management, payers cover most generic drugs for off-label uses because coverage is agnostic of indication. Clinical practice guidelines are highly influential in the widespread adoption of off-label treatments into the standard of care and are often referenced by payers making reimbursement decisions. In oncology, many off-label treatments are included in guidelines; only 62% of treatments in the NCCN are aligned with FDA-approved indications. For example, more than half of the NCCN recommendations for metastatic breast cancer are off-label treatments. Due to the breadth of off-label use, we anticipate payers would continue to cover repurposed generic drugs used off-label, even if there is a pathway available for non-manufacturers to pursue FDA approval.
We do not envision any form of exclusivity being granted for indications pursued via a labeling-only 505(b)(2) NDA. Given that the non-manufacturer sponsor would rely on existing products produced by multiple generic manufacturers, there is no new product to grant exclusivity. Even if some form of exclusivity were given to the non-manufacturer, it would be insufficient to guarantee the use of any particular drug product over another due to pharmacy-level substitution.
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