After the Verdict: How a Handful of U.S. Patients Can Still Legally Receive a Rejected Pain Drug
When the FDA declined to approve tanezumab in 2021, most coverage framed it as the end of the line for a once-promising class of non-opioid painkillers. For the vast majority of patients with osteoarthritis or chronic low back pain who had followed the nerve growth factor (NGF) inhibitor saga, that was effectively true. But not for everyone.
Buried in federal regulation is a set of pathways — expanded access, investigator-initiated research, and compassionate use protocols — that allow certain patients to receive an investigational compound even after a regulatory setback. These mechanisms are legal, documented, and rarely discussed. They are also, for reasons this article will explore, almost inaccessible to the average pain patient.
The Regulatory Back Door Is Intentionally Narrow
Expanded access, sometimes called "compassionate use," is codified in 21st Century Cures Act amendments to the Federal Food, Drug, and Cosmetic Act. It permits a physician, with the sponsor's cooperation and the FDA's sign-off, to administer an unapproved or post-rejection investigational drug to a patient with a serious condition who has exhausted alternatives and cannot enroll in a clinical trial.
Three tiers exist: single-patient emergency access, single-patient non-emergency requests, and intermediate-size or large expanded access protocols. The drug's sponsor must consent to provide it. That last condition is where most pathways quietly end.
After a complete response letter or a withdrawn application, many sponsors freeze their expanded access programs entirely. Supplying a rejected molecule carries liability, manufacturing costs, and — critically for a drug like an NGF inhibitor — the reputational weight of safety signals, including the joint destruction concerns (rapidly progressive osteoarthritis) that dogged the tanezumab program through its Phase III trials. Continuing to distribute the drug means continuing to be responsible for it.
Investigator-Initiated Studies: The Researcher's Route
A second, less visible channel runs through academic medical centers. Under an investigator-initiated (or "investigator-sponsored") study, a physician-researcher at a U.S. institution can request the drug directly from the manufacturer, draft their own protocol, and submit it to the FDA as a new Investigational New Drug application.
For a rejected pain therapeutic, this route offers something expanded access cannot: the chance to generate new data. A researcher might, for example, study a lower dose, a shorter treatment duration, or a carefully screened population — precisely the variables that dosing-strategy analyses suggested mattered in the original tanezumab trials.
But the burden falls on the investigator. The physician must secure drug supply, institutional review board approval, regulatory filings, and funding, often without industry support. In the pain field, where NGF inhibitors have no approved counterpart in the United States, only a small number of such proposals have surfaced publicly since the rejection.
Who Actually Qualifies — and Who Gets In
On paper, the eligibility criteria for expanded access are straightforward: a serious or life-threatening condition, no comparable alternative therapy, inability to enroll in trials, and a favorable risk-benefit judgment by the treating physician.
In practice, chronic pain is a poor fit. Regulators generally reserve expanded access for serious conditions, and while disabling osteoarthritis is serious, an evaluator must also weigh the drug's known risks. For an NGF inhibitor carrying a boxed-worthy joint safety signal, the calculus narrows further. Patients with rapidly progressive osteoarthritis risk factors — pre-existing joint damage, certain imaging findings — may be excluded on safety grounds rather than eligibility ones.
Add the practical requirements: a physician willing to navigate the FDA's Form FDA 3926, a sponsor willing to ship the product, and often an institutional review board review. Each step filters out candidates. The result is that the patients most likely to access a withdrawn pain drug are those already embedded in academic pain centers, with physicians who know the system exists.
How a Patient Can Ask
For patients and families in the U.S., the realistic entry points are:
- Ask the treating specialist directly whether an expanded access request is feasible for the specific compound, and whether the sponsor still holds usable supply.
- Contact the manufacturer's medical affairs department, which handles expanded access inquiries and can state the company's position in writing.
- Search ClinicalTrials.gov for any ongoing or planned studies of the compound, including Phase IV or investigator-initiated work.
- Consult a patient advocacy organization or the FDA's Oncology Center of Excellence model (replicated in other divisions) for navigation help, since the agency's expanded access staff can clarify requirements for physicians.
None of this guarantees access. But the difference between the patients who receive a withdrawn investigational drug and those who never learn it was possible is usually one informed conversation.
Why the Doors Stay Shut
The deeper question is structural. Expanded access was designed as a safety valve, not a distribution system. When a sponsor withdraws a drug after a rejection, the commercial incentives to maintain supply, update labeling, and monitor post-marketing safety all evaporate. Voluntarily keeping those obligations alive for a handful of patients is an act of corporate and institutional goodwill that regulation cannot compel.
For the NGF inhibitor class, the story may not be over — licensing arrangements and continued research abroad suggest the molecule retains scientific interest. Whether any American patient ever receives it again outside a revived trial will depend on whether a sponsor, a researcher, and a regulator all say yes at the same time. The pathway exists. It is simply narrow, quiet, and easy to miss.
