Bristol Myers Squibb has opened a high-stakes patent fight with Amgen over a proposed biosimilar to Opdivo, placing one of the pharmaceutical industry’s largest immuno-oncology franchises at the center of the next major wave of biologic competition. Bristol Myers Squibb, E. R. Squibb & Sons and Japan’s Ono Pharmaceutical filed the case in the United States District Court for the District of Delaware, alleging that Amgen’s proposed nivolumab biosimilar ABP 206 would infringe seven United States patents covering aspects of Opdivo and its use in cancer treatment. The complaint was initially filed on September 8, with a redacted version becoming publicly available several days later.
The litigation arrives at a strategically important moment for Bristol Myers Squibb. Opdivo generated $10.05 billion in worldwide revenue during 2025, including $5.90 billion in the United States, making it one of the company’s most commercially important medicines. Bristol Myers Squibb currently estimates 2028 as the minimum United States market-exclusivity date associated with the core nivolumab composition-of-matter patent, placing the franchise within sight of the biosimilar competition that has already transformed markets for other blockbuster biologics.
Amgen, meanwhile, is not approaching nivolumab as a speculative target. The biotechnology company has an ongoing randomized, double-blind comparative clinical study evaluating ABP 206 against Opdivo in treatment-naïve patients with unresectable or metastatic melanoma. Amgen is simultaneously developing biosimilar candidates targeting other major biologics, including Merck & Co.’s Keytruda and Roche’s Ocrevus, showing that ABP 206 forms part of a wider effort to participate in the approaching loss-of-exclusivity cycle for several of the pharmaceutical industry’s largest products.
What exactly is Bristol Myers Squibb alleging against Amgen?
The lawsuit arises under the United States biosimilar patent framework and alleges infringement involving seven patents. The patents identified in the complaint include claims covering the nivolumab antibody itself as well as methods involving disruption of PD-1 and PD-L1 signaling and particular cancer-treatment approaches. Bristol Myers Squibb and Ono Pharmaceutical are seeking to prevent Amgen from commercially manufacturing or selling ABP 206 in a manner that they contend would infringe those patents.
The allegations remain claims made by Bristol Myers Squibb and Ono Pharmaceutical, not findings that Amgen has infringed valid patents. The case is still at an early stage, and the court has not ruled on the merits. Patent disputes around biosimilars can involve arguments over whether individual patent claims are valid, whether the proposed biosimilar actually infringes them, when a product may legally launch and whether the parties ultimately reach a settlement before trial.
That distinction is particularly important because the dispute extends beyond the basic question of when the original nivolumab molecule loses core protection. Pharmaceutical companies frequently build additional intellectual-property layers around indications, combinations, formulations, dosing schedules and treatment methods. Biosimilar developers, in turn, may challenge those patents or design commercial strategies around particular claims.
Bloomberg Law reported that Bristol Myers Squibb is relying partly on later-expiring treatment patents to defend important Opdivo uses beyond the expiration of foundational protection. That means the case could become an important test of how much practical protection indication and method-of-treatment patents provide as the first major wave of PD-1 biosimilars approaches the United States market.
Why is Opdivo so important to Bristol Myers Squibb?
Opdivo is not simply another aging product approaching patent expiration. It remains one of Bristol Myers Squibb’s largest revenue contributors and an important component of its designated Growth Portfolio.
Worldwide Opdivo revenue reached $10.049 billion in 2025, rising 8% from $9.304 billion a year earlier. United States revenue increased 10% to $5.904 billion, while international sales rose 5% to $4.145 billion. Bristol Myers Squibb has expanded nivolumab across an unusually broad range of cancers, including lung, kidney, bladder, colorectal, melanoma, liver, head and neck, blood, gastric and esophageal malignancies.
Revenue has begun shifting during 2026 as Bristol Myers Squibb moves some patients toward the subcutaneous formulation Opdivo Qvantig. During the second quarter, conventional Opdivo revenue fell approximately 4% to around $2.5 billion, with management attributing much of the decline to conversion toward Qvantig in the United States. Opdivo Qvantig generated approximately $261 million during the quarter and was already running at an annualized revenue rate above $1 billion.
That lifecycle strategy is commercially significant. A subcutaneous formulation can reduce administration time compared with intravenous infusion and may preserve physician and patient loyalty to the nivolumab franchise even as biosimilars targeting conventional Opdivo emerge.
However, Bristol Myers Squibb’s own regulatory filings state that the estimated minimum United States market-exclusivity date for Opdivo Qvantig is also 2028 based on the nivolumab composition-of-matter patent, excluding any potential additional protection arising from pending patents covering the Qvantig formulation and use. The ultimate durability of that additional intellectual property could therefore become an increasingly important part of the franchise’s post-2028 economics.
Why is Amgen targeting Opdivo when it already sells innovative medicines?
Amgen occupies an unusual position because it is simultaneously a major innovative biotechnology company and one of the world’s most established biosimilar developers. The company has previously launched biosimilars against blockbuster biologics across oncology and inflammatory disease, giving it manufacturing, clinical-development and commercialization capabilities that smaller generic-drug companies may struggle to replicate.
ABP 206 fits that model. Amgen is conducting comparative clinical testing against Opdivo in previously untreated unresectable or metastatic melanoma, seeking to establish that the proposed biosimilar has no clinically meaningful differences from the reference medicine within the regulatory requirements governing biosimilar approval.
The attraction is easy to understand. Opdivo generated more than $10 billion globally last year, and PD-1 inhibitors are embedded across numerous oncology treatment pathways. Even a fraction of that volume could create a meaningful commercial opportunity once biosimilar competition becomes legally and regulatorily possible.
Amgen is also developing ABP 234 as a proposed biosimilar to Merck & Co.’s Keytruda and ABP 692 as a proposed biosimilar to Roche’s Ocrevus. The pipeline indicates that Amgen sees the next biologic patent cycle as a portfolio opportunity rather than a one-product event.
That is particularly significant because PD-1 drugs have historically been viewed as cutting-edge oncology products rather than conventional biologics exposed to commoditization. As patents expire, however, immuno-oncology may begin following a pattern already seen with trastuzumab, rituximab and bevacizumab, where biosimilars gradually altered purchasing, payer behavior and pricing.
Could an Opdivo biosimilar materially reduce cancer treatment costs?
Biosimilars typically compete differently from conventional small-molecule generics. Manufacturing biologic medicines is considerably more complex, so price reductions are generally less dramatic than the steep discounts that can follow conventional generic entry.
Nevertheless, competition can still produce meaningful savings because biologic cancer therapies are expensive and often administered repeatedly. Hospitals, insurers and healthcare systems have strong incentives to shift utilization toward lower-cost alternatives when physicians and regulators consider them clinically appropriate.
The economic consequences can extend beyond the reference product itself. A lower-priced nivolumab biosimilar could influence negotiations around competing PD-1 therapies, combinations and hospital formularies, particularly in indications where several immunotherapies offer clinically viable options.
That makes the coming patent cycle strategically relevant not just for Bristol Myers Squibb and Amgen, but also for Merck & Co., Roche, AstraZeneca and other companies operating large immuno-oncology franchises.
The potential savings must still be balanced against indication coverage and interchangeability rules. A biosimilar may not necessarily enter every Opdivo indication immediately, and litigation around method-of-use patents can affect which portions of a reference medicine’s label a competitor can pursue at launch.
Why could the seven-patent dispute extend beyond the basic 2028 patent cliff?
Bristol Myers Squibb has historically identified 2028 as the estimated United States loss-of-exclusivity point associated with Opdivo’s composition-of-matter protection. Yet the new case shows why patent cliffs are rarely a single-date event.
One of the patents cited in the litigation includes claims relating to nivolumab’s amino-acid sequence, while others address particular immunotherapy methods and cancer-treatment combinations. Some of those patents extend beyond the original foundational protection, potentially giving Bristol Myers Squibb arguments for restricting certain uses even if competitors clear earlier patent barriers.
Amgen may challenge those claims, contend that ABP 206 does not infringe them, or negotiate a settlement defining a future launch date. Similar settlements are common in pharmaceutical patent litigation because they can provide both sides with greater commercial certainty than years of litigation.
For Bristol Myers Squibb, every additional period of exclusivity can be financially meaningful when the reference medicine generates billions of dollars annually. For Amgen, an earlier launch creates a first-mover opportunity before multiple nivolumab biosimilars potentially enter the market.
The incentives on both sides therefore make the Delaware litigation strategically important even though commercial competition may still be years away.
How is Bristol Myers Squibb preparing for the broader loss-of-exclusivity cycle?
The Opdivo litigation arrives as Bristol Myers Squibb is already managing patent erosion across older medicines and shifting its revenue base toward newer products.
Second-quarter 2026 revenue reached approximately $12.97 billion, up nearly 6% year over year, while the company’s Growth Portfolio expanded about 14% to $7.6 billion and represented almost 60% of total revenue. Bristol Myers Squibb also raised its full-year outlook after stronger-than-expected quarterly performance.
Newer products including Reblozyl, Breyanzi, Camzyos, Sotyktu, Cobenfy and Opdivo Qvantig are increasingly important as legacy franchises encounter generic or biosimilar competition. This is exactly the transition major pharmaceutical companies must execute before patent losses occur: replacing concentrated blockbuster revenue with several growing franchises rather than waiting for erosion and then attempting to rebuild.
Opdivo presents a somewhat unusual case because Bristol Myers Squibb is simultaneously trying to defend the original medicine, convert patients toward Qvantig, expand nivolumab into additional indications and develop other oncology assets capable of assuming greater revenue responsibility.
The litigation with Amgen therefore should not be interpreted as a sign that Bristol Myers Squibb expects to preserve conventional Opdivo economics indefinitely. It is better understood as one component of a broader lifecycle-management effort designed to slow erosion while newer products mature.
What does the dispute mean for Bristol Myers Squibb and Amgen shares?
Bristol Myers Squibb shares closed at approximately $62.92 on September 18, leaving the stock below its August 52-week high but still supported by stronger-than-expected second-quarter results and improved 2026 guidance. The company’s valuation increasingly reflects a balance between near-term cash generation from established products and investor confidence that newer medicines can offset future patent losses.
Amgen shares finished September 18 at $385.65, gaining 1.55% during the session and marking a third consecutive advance, although the stock remained about 13.7% below its August 25 high. Recent Amgen sentiment has been shaped by several issues beyond biosimilars, including its innovative pipeline, changes to Imdelltra monitoring requirements and cardiovascular-development concerns, making it inappropriate to attribute short-term share moves specifically to the Opdivo dispute.
For both companies, the lawsuit is more relevant to long-term portfolio economics than immediate quarterly earnings. Amgen is still developing ABP 206, while Bristol Myers Squibb retains substantial current Opdivo sales and additional time before the core United States exclusivity date it identifies for business-planning purposes.
Investor attention is likely to increase as ABP 206 advances toward potential regulatory submission and the court defines which patent claims remain in dispute.
What should happen next in the Opdivo biosimilar battle?
The Delaware case will proceed through the complex patent process governing proposed biosimilars, potentially involving claim construction, validity arguments, infringement analysis and negotiations between the companies. Settlement remains possible at almost any stage, and previous pharmaceutical patent cases show that an agreed future launch date can sometimes emerge long before a final trial judgment.
Amgen’s clinical program is the other major variable. ABP 206 must satisfy regulatory standards before it can become a commercial threat regardless of the patent outcome. Its ongoing melanoma study therefore matters alongside the courtroom proceedings.
Bristol Myers Squibb will meanwhile continue attempting to migrate parts of the nivolumab franchise toward Opdivo Qvantig and broaden the drug’s use through additional indications and combinations. The company’s ability to protect newer formulation and treatment intellectual property may determine how much economic value survives after conventional Opdivo faces biosimilar competition.
The larger industry implications extend well beyond one lawsuit. Opdivo and Keytruda helped create the modern PD-1 immunotherapy market and collectively transformed treatment across numerous cancers. Their approaching patent expirations mean the next phase of immuno-oncology may be shaped as much by biosimilar economics, patent strategy and hospital purchasing as by clinical innovation.
Bristol Myers Squibb’s lawsuit against Amgen is an early sign that this transition is no longer theoretical. The commercial battle over the first generation of blockbuster cancer immunotherapies has begun before the first competing United States nivolumab biosimilar has even reached the market.
