How Do Biosimilars Reshape Pharmaceutical Investment?

Biosimilars — FDA-approved copies of biologic reference drugs that are highly similar but not identical — are reshaping the competitive dynamics of pharmaceutical's largest drug classes. Unlike small-molecule generics that can exactly replicate a reference drug's molecule, biosimilars are manufactured through living cell processes that cannot be precisely replicated, creating a more gradual and less complete competitive dynamic than traditional generic substitution. Understanding biosimilar market penetration rates, pricing dynamics, interchangeability designations, and the financial impact on reference product revenues helps investors evaluate both biosimilar manufacturers as investment opportunities and reference product manufacturers facing competitive threat.

Quick definition: Biosimilars are biological medicines that are highly similar to an already-approved reference biologic, with no clinically meaningful differences in safety or efficacy. They require their own FDA approval through an abbreviated biological license application pathway, demonstrating biosimilarity through analytical, clinical pharmacology, and clinical studies. Biosimilar entry typically results in 20–40% price discounts (versus 70–90% for small-molecule generics) and slower market share erosion for the reference product.

Key takeaways

• Humira's US biosimilar market (launched January 2023) demonstrated that biologic drug biosimilar competition is real but gradual — with multiple biosimilar entrants achieving meaningful share but leaving substantial AbbVie brand revenue intact into 2024
• FDA's interchangeability designation (allowing pharmacist substitution without physician authorization, similar to generic substitution) is essential for biosimilar market penetration — biosimilars without interchangeability require physician conversion rather than automatic substitution
• Biosimilar manufacturers include Amgen, Pfizer, Samsung Bioepis (Samsung subsidiary), Sandoz (Novartis subsidiary), Celltrion (Korean manufacturer), and Coherus Biosciences — creating a distinct biosimilar industry ecosystem
• Biologic drug revenue erosion from biosimilar competition is approximately 30–50% within 5 years of biosimilar launch — compared to approximately 80–90% small-molecule generic erosion within 12–18 months
• The next major biosimilar wave targets drugs with expirations in 2025–2030: Stelara (ustekinumab, Johnson & Johnson), Keytruda (pembrolizumab, Merck), Eylea (aflibercept, Regeneron), and Prolia/Xgeva (denosumab, Amgen)

Biologics versus small-molecule generics

Manufacturing complexity: Small-molecule drugs are chemically synthesized — a defined molecular structure that can be exactly replicated by any manufacturer with the right chemistry capabilities. Generic manufacturers can create identical copies with equivalent pharmacokinetic profiles. Biologic drugs are manufactured through living cells (bacteria, yeast, or mammalian cells) that produce complex proteins. The protein's three-dimensional structure, post-translational modifications (glycosylation patterns), and aggregate content depend on the specific cell line and manufacturing conditions — parameters that cannot be exactly copied.

Analytical biosimilarity assessment: Biosimilar approval requires extensive analytical comparison demonstrating that the biosimilar is highly similar to the reference biologic in primary and higher-order structure, post-translational modifications, biological activity, and immunogenicity potential. Modern analytical techniques (mass spectrometry, protein characterization methods) can detect structural differences at parts-per-billion levels — but some structural heterogeneity is inherent in all biologic manufacturing.

Regulatory pathway: The Biologics Price Competition and Innovation Act (BPCIA, 2010) established the US biosimilar approval pathway — requiring biosimilar applicants to demonstrate biosimilarity through a "totality of evidence" approach. The FDA's Center for Drug Evaluation and Research (CDER) and Center for Biologics Evaluation and Research (CBER) evaluate biosimilar applications. Data exclusivity provisions (12 years for reference biologics) prevent biosimilar applications from referencing reference product data until the exclusivity period expires.

Humira biosimilar case study

January 2023 US launch: AbbVie successfully delayed US Humira biosimilar entry until January 2023 through a complex patent settlement strategy — reaching license agreements with multiple biosimilar manufacturers that allowed delayed entry in exchange for perpetual royalty-free licenses once the entry date arrived. This strategy extended Humira's US revenue by approximately 5 years relative to when the patents could first have been challenged.

Multiple biosimilar entrants: Seven biosimilars launched in the US Humira market in 2023: Amgen's Amjevita, Boehringer Ingelheim's Cyltezo (with interchangeability designation), Samsung Bioepis's Hadlima (interchangeable), Sandoz's Hyrimoz, Pfizer's Abrilada, Organon's Hadlima, and Fresenius Kabi's Idacio. This unprecedented multi-biosimilar launch created a competitive dynamic with both "citrate-free" (reduced injection site pain) and "high-concentration" formulations competing on both price and formulation attributes.

AbbVie's managed transition: AbbVie launched its own "high-concentration, citrate-free" Humira formulation (which retained more favorable characteristics than the original US formulation) to retain patients who might otherwise switch to biosimilars. AbbVie also negotiated preferred formulary positioning with pharmacy benefit managers — accepting lower net pricing to maintain preferred access and patient retention.

Revenue decline pattern: AbbVie's Humira US net revenue declined from approximately $17 billion (2022) to approximately $12 billion (2023) — approximately 30% in the first year. This decline rate, while significant, was less severe than many analysts feared, demonstrating biologic market erosion dynamics: physician hesitancy to switch stable patients, payer formulary management programs, and patient preference persistence slow biosimilar penetration relative to small-molecule generics.

How it flows

Interchangeability and market penetration

Interchangeability designation mechanics: FDA's interchangeability designation allows pharmacists to substitute a biosimilar for a prescribed reference biologic without physician intervention — similar to generic drug substitution. Achieving interchangeability requires demonstrating in switching studies that patients alternating between the biosimilar and reference product experience no additional risk. This additional clinical evidence requirement means interchangeability approval comes after initial biosimilar approval.

Market penetration differences: Biosimilars with interchangeability designations penetrate markets more rapidly because pharmacy-level substitution can occur automatically. Biosimilars without interchangeability require physician conversion — active prescribing decisions to switch patients from the reference product to the biosimilar. This distinction creates substantial market penetration rate differences.

Pharmacy benefit manager formulary levers: PBMs can drive biosimilar adoption through formulary management — requiring step therapy (try biosimilar first before reference product), setting biosimilars as preferred with lower patient cost-sharing, or excluding the reference product from formulary. These formulary tools are more effective when the biosimilar has interchangeability designation that enables smooth pharmacy-level substitution.

Biosimilar manufacturing landscape

Amgen's biosimilar strategy: Amgen has built a major biosimilar portfolio — Amjevita (Humira biosimilar), Mvasi (Avastin biosimilar), Kanjinti (Herceptin biosimilar), and multiple pipeline biosimilars. Amgen leverages its biologic manufacturing expertise to compete in biosimilars while also protecting its own reference biologic revenues (Enbrel, Prolia, Repatha) from biosimilar competition — creating an inherent tension in Amgen's competitive positioning.

Samsung Bioepis and Celltrion: South Korean manufacturers Samsung Bioepis (joint venture of Samsung BioLogics) and Celltrion have emerged as major global biosimilar developers — leveraging Korea's advanced biopharmaceutical manufacturing capabilities and relatively lower-cost clinical development operations. Samsung Bioepis has multiple FDA-approved biosimilars; Celltrion's infliximab biosimilar (Inflectra, biosimilar to Remicade) was among the first FDA-approved biosimilars.

Sandoz (Novartis subsidiary): Sandoz, the global generics and biosimilars division of Novartis, is a major biosimilar developer with an extensive pipeline. Novartis has considered separating or spinning off Sandoz to allow the biosimilar business to pursue its strategy independently — acknowledging that biosimilar economics and customer focus differ from Novartis Innovative Medicines.

Upcoming biosimilar waves

Stelara (ustekinumab): Johnson & Johnson's Stelara (ustekinumab, an IL-12/23 inhibitor for psoriasis and Crohn's disease) generating approximately $10 billion annually faces biosimilar entry — US data exclusivity expired in 2023 with multiple biosimilars in development. J&J's Stelara revenue cliff will test the biologic erosion pattern across a different IL-inhibitor drug class from the TNF-inhibitor category tested with Humira.

Keytruda (pembrolizumab): Merck's Keytruda faces biosimilar pressure beginning in the late 2020s as patents expire. A pembrolizumab biosimilar market could be among the largest biosimilar competitions in history given Keytruda's approximately $25 billion annual revenue. Merck's SubQ pembrolizumab formulation (versus current IV infusion) may create a formulation-based competitive moat if launched successfully before biosimilar entry.

Eylea (aflibercept): Regeneron's Eylea (intravitreal injection for wet AMD and diabetic macular edema) generates approximately $8–9 billion annually. Biosimilar competition began in 2023; Regeneron's Eylea HD (higher-concentration formulation with longer dosing intervals) provides a product lifecycle management tool to retain patient preference.

Investment implications

Reference product manufacturer strategy: Pharmaceutical companies defending biologic drugs from biosimilar competition employ several strategies: (1) product lifecycle management — new formulations, devices, or concentrations that provide clinical advantages; (2) patient support programs that reduce switching friction; (3) formulary negotiations that maintain preferred access even at lower net prices; and (4) pipeline transition to next-generation biologic or oral alternatives.

Biosimilar manufacturer investment: Investing directly in biosimilar manufacturers requires different analysis than reference product pharmaceutical investing — biosimilar economics are volume-driven (market share capture at lower prices) rather than pricing-power-driven. Biosimilar companies generate acceptable returns when manufacturing costs are well below reference product pricing, when interchangeability enables automated substitution, and when development costs are contained through efficient clinical programs.

Patent cliff modeling: For pharmaceutical companies with major biologic drugs approaching exclusivity expiration, investor analysis should model: (1) when the first biosimilar can realistically enter (combining patent, data exclusivity, and approval timelines); (2) what price discount biosimilars will achieve; (3) what market share rate biosimilars will capture; and (4) what formulation lifecycle management options exist. FDA's Purple Book (licensed biological products database) provides reference product exclusivity information at fda.gov.

Common mistakes

Applying small-molecule generic erosion rates to biologic biosimilar modeling. Biosimilar market penetration is fundamentally different from small-molecule generic entry — 30–50% reference product revenue retention 5 years after biosimilar entry is the biologic analog of small-molecule generic 80–90% erosion within 18 months. Models that apply generic drug erosion rates to biosimilar competition substantially overestimate biologic revenue decline.

Ignoring interchangeability status in biosimilar adoption forecasting. Biosimilars without interchangeability designations face structural market penetration barriers that significantly slow adoption relative to interchangeable biosimilars. Any biosimilar market penetration model must incorporate interchangeability status as a primary variable.

FAQ

What is the "patent dance" and how does it affect biosimilar entry timing?

The BPCIA created a complex patent dispute resolution mechanism — informally called the "patent dance" — requiring biosimilar applicants to exchange patent information with reference product holders and participate in an elaborate process for identifying patents to be litigated before biosimilar launch. Companies can opt out of the dance and face patent infringement immediately upon launch. The dance allows some strategic delay of biosimilar entry but ultimately cannot prevent market entry once clinical and regulatory requirements are met. FDA Purple Book data and pharmaceutical company patent litigation disclosures (Form 10-K legal proceedings sections) provide information about biosimilar entry timelines.

Related concepts

• Pharmaceutical and Biotech Analysis
• Healthcare Competitive Moats
• Healthcare M&A
• Healthcare Regulation
• Healthcare Global Exposure

Summary

Biosimilar competition reshapes pharmaceutical company competitive dynamics more gradually and less completely than small-molecule generic competition — reference products retain approximately 50–70% of revenue 5 years after biosimilar entry versus approximately 10–20% for small-molecule drugs. Humira's US biosimilar market (seven biosimilars launched January 2023) demonstrated this pattern: AbbVie's US Humira revenue declined approximately 30% in the first year — significant but less severe than generic drug analogs. Interchangeability designation enables pharmacist substitution and substantially accelerates biosimilar market penetration; biosimilars without interchangeability require active physician conversion. The next major biosimilar wave includes Stelara (J&J, approximately $10B), Keytruda (Merck, approximately $25B), and Eylea (Regeneron, approximately $9B) — the Keytruda biosimilar market will be the most significant test of checkpoint inhibitor biosimilar dynamics. Pharmaceutical investors must model biologic drug patent cliffs with biosimilar-appropriate erosion rates rather than generic drug rates.

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