Last updated: September 4, 2026
Oprelvekin, marketed as Neumega, is a recombinant human interleukin-11 approved by the FDA in 1997 to reduce severe chemotherapy-induced thrombocytopenia in adults with nonmyeloid malignancies. Its commercial trajectory ended in the United States after Wyeth voluntarily withdrew the product in 2007 for business reasons. The withdrawal was not an FDA safety recall, but safety liabilities, narrow use, injectable administration, and competition from platelet transfusion and newer thrombopoietin-receptor agonists limited its value.
No current U.S. commercial market exists for Neumega. Oprelvekin has no meaningful active U.S. regulatory exclusivity, no established biosimilar pipeline, and no publicly reported standalone revenue stream. Its remaining value is primarily historical, geographic, or related to any residual know-how rather than a viable branded pharmaceutical franchise.
What is oprelvekin and what was Neumega approved to treat?
Oprelvekin is a recombinant form of human interleukin-11, a cytokine involved in megakaryocyte development and platelet production. Neumega was administered subcutaneously at a dose of 50 micrograms per kilogram once daily.
The FDA indication covered adult patients with nonmyeloid malignancies who were receiving myelosuppressive anticancer chemotherapy and had a significant risk of severe thrombocytopenia. The product was intended for patients in whom prior chemotherapy had produced severe thrombocytopenia and where the treating physician expected a similar risk from subsequent chemotherapy [1].
The product was not positioned as a universal replacement for platelet transfusions. The label excluded several important settings, including routine use after myeloablative chemotherapy and use in pediatric patients. Treatment generally began after chemotherapy and continued until platelet recovery, subject to a maximum treatment period under the prescribing information [1].
What clinical and safety factors affected demand?
Oprelvekin had a difficult risk-benefit profile for a supportive-care product. Reported adverse effects included:
- Fluid retention and peripheral edema
- Dyspnea and pulmonary congestion
- Tachycardia and atrial arrhythmias
- Conjunctival injection
- Headache and fatigue
- Injection-site reactions
- Potential worsening of pre-existing cardiovascular disease
The label warned about serious cardiovascular events, including atrial arrhythmias, pulmonary edema, and other consequences of fluid retention [1]. These risks were commercially important because the target population consisted of patients with cancer who often had substantial baseline cardiovascular and renal comorbidity.
The product also had a delayed and variable effect on platelet recovery. Physicians could use platelet transfusion when an immediate correction was required. That reduced the practical value of a daily injectable drug with clinically meaningful monitoring requirements.
When was Neumega approved and when was it withdrawn?
The FDA approved Neumega in 1997. Wyeth later withdrew the product from the U.S. market, with the withdrawal becoming effective in 2007. The withdrawal was voluntary and was attributed to commercial considerations rather than an FDA determination that the product was unsafe or ineffective [2].
| Milestone |
Date |
Commercial significance |
| FDA approval of Neumega |
1997 |
Established the first major U.S. regulatory market for recombinant interleukin-11 in oncology supportive care |
| U.S. post-approval commercialization |
Late 1990s |
Adoption concentrated in selected high-risk chemotherapy patients |
| Increasing safety and utilization constraints |
Early 2000s |
Cardiovascular and fluid-retention concerns narrowed use |
| Wyeth voluntary U.S. withdrawal |
2007 |
Ended the principal branded U.S. revenue stream |
| Pfizer acquisition of Wyeth |
2009 |
Ownership of residual assets moved to Pfizer |
| Current U.S. position |
No active commercial franchise |
No established branded market or active U.S. exclusivity |
The withdrawal date is more important than the nominal patent expiry date for commercial analysis. Even if intellectual-property rights had remained in force in some jurisdictions, the U.S. commercial opportunity had already contracted sharply by the time of withdrawal.
What was the financial trajectory of oprelvekin?
Public company filings did not generally disclose Neumega revenue as a separate product line. Wyeth reported revenue at broader product or business-unit levels, preventing a reliable standalone sales series. The available financial record supports a qualitative trajectory rather than a precise revenue curve.
Launch and early adoption
Neumega entered a market with a clear clinical problem: chemotherapy-induced thrombocytopenia could delay treatment, increase transfusion use, and raise hospital costs. The product offered a biologic mechanism intended to accelerate platelet recovery and reduce the need for platelet transfusions.
Its commercial opportunity was limited from the outset by:
- A narrow labeled population.
- Use only in selected chemotherapy regimens.
- Subcutaneous daily dosing.
- Delayed onset relative to transfusion.
- Cardiovascular and fluid-retention warnings.
- Dependence on oncologist willingness to use prophylactic supportive care.
These factors made Neumega a specialty oncology product rather than a broad hospital or primary-care medicine.
Mature-market contraction
During the early 2000s, the product faced pressure from its clinical profile and from changing oncology practice. Physicians had alternatives, including platelet transfusion, chemotherapy modification, dose delay, and supportive-care protocols. Payers also had incentives to restrict expensive prophylactic products when the clinical benefit was uncertain for lower-risk patients.
Oprelvekin’s market was especially vulnerable because the treatment objective was prevention of a complication rather than treatment of a disease with no practical alternative. The product had to demonstrate that preventing thrombocytopenia justified both its acquisition cost and its monitoring burden.
Post-withdrawal value
After the U.S. withdrawal, the commercial value of Neumega declined to residual levels. Pfizer’s acquisition of Wyeth transferred the asset into a much larger portfolio, but there is no public evidence that Pfizer restarted broad U.S. commercialization or invested in a new development program for oprelvekin.
The financial profile can be summarized as follows:
| Period |
Revenue profile |
Primary drivers |
| 1997-2000 |
Initial specialty-product revenue |
New mechanism, unmet need, oncology supportive care |
| 2001-2005 |
Mature but constrained sales |
Safety concerns, narrow label, transfusion competition |
| 2006-2007 |
Declining commercial value |
Weak product economics and limited utilization |
| After 2007 |
No meaningful U.S. branded revenue |
Voluntary withdrawal |
| Current |
No publicly reported standalone revenue |
No active U.S. franchise |
What patents protected oprelvekin?
Oprelvekin was protected primarily through patents covering recombinant interleukin-11, DNA sequences, expression systems, compositions, and therapeutic use. The asset originated with Genetics Institute, which became part of Wyeth before Wyeth was acquired by Pfizer.
The original patent estate no longer creates a material U.S. market barrier. Patent protection associated with the original recombinant protein and early manufacturing technology would have expired years ago, including any applicable patent-term adjustment or restoration. The five-year new chemical entity exclusivity period from the 1997 approval also expired long before the commercial withdrawal.
What is the Orange Book status of Neumega?
The Orange Book status is commercially inactive because the U.S. reference product is no longer marketed. The product does not have a current, meaningful period of FDA market exclusivity that would block a new application.
There is no active commercial generic market comparable to the markets for small-molecule drugs. A company seeking to reintroduce oprelvekin would face a development, manufacturing, and reimbursement problem rather than a conventional patent cliff.
The principal intellectual-property barriers would now relate to:
- Cell-line and expression-system know-how
- Protein folding and purification
- Manufacturing process consistency
- Stability and container-closure systems
- Clinical evidence for a modern oncology population
- Any newly developed formulation or delivery technology
A new formulation, dosing regimen, combination, or method of use could theoretically support later patent protection. Such protection would not restore the expired core composition rights and would need a commercially differentiated clinical proposition.
Are there formulation patents or method-of-use patents for oprelvekin?
The historical patent estate likely included claims directed to pharmaceutical compositions and therapeutic administration, but these rights do not provide a current broad U.S. exclusivity position. The original product was an injectable biologic with a relatively conventional subcutaneous presentation.
Potentially protectable areas for a modern product would include:
- Long-acting oprelvekin formulations
- Reduced-immunogenicity protein variants
- Stable liquid formulations
- Lyophilized products with improved reconstitution
- Combination therapy with chemotherapy
- Use in defined thrombocytopenia-risk populations
- Dosing schedules that reduce fluid-retention risk
- Outpatient administration protocols
A new patent would have to overcome substantial obviousness and enablement challenges. A formulation patent would also need to produce a commercially relevant benefit, such as lower dosing frequency, improved stability, or a demonstrable reduction in cardiovascular toxicity.
How does oprelvekin compare with competing platelet-raising therapies?
Oprelvekin no longer has a strong competitive position. The main alternatives are platelet transfusions, treatment modification, and thrombopoietin-receptor agonists.
| Therapy |
Mechanism |
Main commercial position |
Relevance to oprelvekin |
| Oprelvekin |
Interleukin-11 stimulation of megakaryopoiesis |
Withdrawn in the U.S. |
Historical comparator |
| Platelet transfusion |
Immediate replacement of circulating platelets |
Established hospital intervention |
Direct practical substitute |
| Romiplostim |
Thrombopoietin-receptor agonist |
Chronic immune thrombocytopenia; selected off-label oncology use |
Competes through platelet stimulation |
| Eltrombopag |
Oral thrombopoietin-receptor agonist |
Immune thrombocytopenia and other hematologic indications |
Oral administration provides convenience |
| Avatrombopag |
Oral thrombopoietin-receptor agonist |
Immune thrombocytopenia and procedure-related thrombocytopenia |
Competes on convenience in defined settings |
| Lusutrombopag |
Oral thrombopoietin-receptor agonist |
Periprocedural thrombocytopenia in chronic liver disease |
Indication-specific alternative, not a direct replacement |
| Chemotherapy modification |
Treatment adjustment |
Used when clinically acceptable |
Avoids drug acquisition cost |
Romiplostim, eltrombopag, and avatrombopag were not originally direct substitutes for Neumega in the same FDA-approved oncology indication. Their commercial relevance comes from broader thrombopoietic development, oral or less frequent administration, and improved positioning in defined hematologic settings.
Oprelvekin’s main weakness was not simply competition from another drug. It was competition from a treatment pathway that included observation, transfusion, dose modification, and hospital protocols.
What generic entry risks exist for oprelvekin?
Conventional generic entry risk is low because the product is an injectable biologic and the reference product is not actively marketed in the United States. The relevant pathway would be a biosimilar or interchangeable biologic application under the Public Health Service Act, not an ordinary abbreviated new drug application.
A potential entrant would face four commercial barriers:
- The reference product is withdrawn and may offer limited regulatory-commercial value as a comparator.
- Clinical demand is narrow.
- Manufacturing recombinant interleukin-11 is technically specialized.
- Reimbursement would be uncertain without a clear improvement over platelet transfusion or newer agents.
A biosimilar development program would be difficult to justify unless the sponsor had a low-cost manufacturing platform, established oncology distribution, and a targeted market outside the United States.
Which companies are challenging or developing around oprelvekin?
There is no prominent current U.S. Paragraph IV litigation program focused on oprelvekin. The product’s original patent barriers are too old, and the reference product’s withdrawal reduces the commercial incentive for a patent challenge.
The relevant competitive activity has shifted to companies commercializing thrombopoietin-receptor agonists:
- Amgen, through romiplostim
- Novartis, through eltrombopag rights historically associated with the Promacta/Revolade franchise
- Sobi, through avatrombopag in relevant markets
- Shionogi, through lusutrombopag
These companies are not generally challenging Neumega patents. They compete for the broader clinical and economic need to increase platelet counts or avoid platelet transfusion.
What litigation and settlement agreements affect oprelvekin?
No major current patent litigation or settlement agreement materially affects the U.S. commercial outlook for oprelvekin. The key legal event was the voluntary product withdrawal rather than a patent dispute.
The absence of active litigation does not indicate a strong patent estate. It reflects the product’s commercial decline and the lack of an attractive generic or biosimilar launch opportunity.
What is the global market position of oprelvekin?
Oprelvekin had regulatory exposure outside the United States, but its international commercial importance was limited. European and other market authorizations were subject to the same clinical and economic constraints that affected the U.S. product. Withdrawal or discontinuation decisions in individual jurisdictions may not have occurred on the same date.
The global opportunity was restricted by:
- High oncology supportive-care budget scrutiny
- Availability of platelet transfusion
- Hospital-based administration
- Safety concerns in older and comorbid patients
- Small eligible population
- Limited differentiation from other platelet-raising approaches
There is no basis for treating oprelvekin as a current global growth asset.
What would a generic or relaunch scenario require?
A commercially credible relaunch would require more than expired-patent access. A sponsor would need to establish:
- A clearly defined modern patient population
- Evidence of reduced transfusion use or fewer chemotherapy delays
- A safer cardiovascular profile
- A lower-frequency or oral-adjacent delivery strategy
- A competitive acquisition price
- Reimbursement support
- Manufacturing capacity for a recombinant cytokine
- A regulatory plan addressing the withdrawn reference product
The strongest relaunch concept would probably involve a differentiated formulation or a narrowly selected population at high risk of chemotherapy-induced thrombocytopenia. A simple reintroduction of the historical Neumega product would have weak commercial prospects.
How strong is the oprelvekin patent estate?
The original estate is commercially weak in the United States. Core composition and early technology patents are historical rights, not current barriers. Any remaining value would depend on jurisdiction-specific status, unexpired secondary patents, trade secrets, manufacturing capabilities, or newly developed formulations.
| Asset category |
Current strategic strength |
| Original recombinant protein claims |
Low |
| Early manufacturing claims |
Low to moderate, depending on jurisdiction and claim scope |
| Historical method-of-use claims |
Low |
| New formulation opportunity |
Potentially moderate, but requires new data |
| Manufacturing know-how |
Potentially relevant |
| Regulatory exclusivity |
None of practical current significance |
| Biosimilar deterrence |
Limited by small market and withdrawn reference product |
Key Takeaways
- Oprelvekin is recombinant human interleukin-11, formerly marketed by Wyeth as Neumega.
- The FDA approved it in 1997 for selected adults at high risk of severe chemotherapy-induced thrombocytopenia.
- Wyeth voluntarily withdrew Neumega from the U.S. market in 2007 for commercial reasons.
- Cardiovascular toxicity, fluid retention, daily injection, delayed platelet recovery, and platelet-transfusion competition constrained uptake.
- Standalone Neumega revenue was not separately disclosed in public company filings.
- The original U.S. patent and regulatory exclusivity position is no longer commercially meaningful.
- No major current Paragraph IV challenge, patent settlement, or biosimilar launch program drives the asset.
- Any future value would require a new formulation, safer dosing strategy, or narrowly targeted oncology indication.
- Oprelvekin is best assessed as a withdrawn historical product, not an active branded growth opportunity.
FAQs
Is oprelvekin still FDA approved?
The historical Neumega approval established the product’s FDA regulatory status, but the product was voluntarily withdrawn from the U.S. market in 2007 and is not an active U.S. commercial franchise.
Can a company launch a generic version of Neumega?
A conventional generic pathway is unlikely to be sufficient because oprelvekin is a recombinant biologic. A biosimilar application would be more relevant, but the small market and withdrawn reference product reduce commercial incentives.
Did Pfizer acquire oprelvekin?
Pfizer acquired Wyeth in 2009, thereby acquiring Wyeth’s residual rights and liabilities associated with Neumega. The acquisition did not produce a major U.S. relaunch.
Was Neumega withdrawn because of safety concerns?
The U.S. withdrawal was described as voluntary and commercially driven, rather than an FDA withdrawal for safety or lack of effectiveness. Safety warnings nevertheless contributed to limited clinical adoption.
Could oprelvekin regain value in oncology?
A relaunch would require clinical and commercial differentiation, such as a safer long-acting formulation or evidence that treatment reduces transfusions and chemotherapy delays in a clearly defined high-risk population.
References
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U.S. Food and Drug Administration. (2002). Neumega (oprelvekin) prescribing information. FDA.
-
U.S. Food and Drug Administration. (2007). Withdrawal of approval of the biologics license application for Neumega (oprelvekin). FDA.
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Wyeth. (2008). Annual report 2007. Wyeth.
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Pfizer Inc. (2010). Annual report 2009. Pfizer.
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U.S. Food and Drug Administration. (2024). Orange Book: Approved drug products with therapeutic equivalence evaluations. FDA.
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U.S. Food and Drug Administration. (2024). Purple Book: Database of licensed biological products. FDA.
