To understand why the study matters, it helps to understand what biosimilars are and how they differ from the generic drugs most consumers know. Conventional small-molecule medications can be copied exactly, and their generics must demonstrate bioequivalence through relatively straightforward testing. Biologic drugs, by contrast, are large, complex molecules manufactured inside living cells, which makes them inherently variable and impossible to replicate precisely. Biosimilars are therefore defined as products that are highly similar to an originator biologic, with no clinically meaningful differences in safety, purity or potency. A federal policy enacted in 2009 established an abbreviated regulatory pathway designed to bring these products to the U.S. market, with the explicit goals of increasing competition, lowering prices and improving access to biologic treatments. By the end of 2024, thirteen biosimilars had been approved for three of the most widely used cancer biologics: bevacizumab, rituximab and trastuzumab, drugs deployed against breast cancer, lymphoma, colorectal cancer, lung cancer and ovarian cancer.

The financial stakes in oncology could hardly be higher. Previous research has estimated that financial toxicity, the measurable hardship caused by the cost of care, may affect as many as half of all patients with cancer in the United States. That hardship is not merely a matter of household budgets; it has been linked to medication nonadherence and poorer health outcomes, meaning that high drug prices can directly undermine the effectiveness of treatment. Biologic drugs are a major contributor to this burden because of their complexity and cost. While earlier studies had shown that biosimilar competition in other therapeutic areas can drive down prices and shift prescribing toward cheaper alternatives, far less was known about what happened across these three major cancer drugs after biosimilar entry, and crucially, whether any market changes actually translated into lower costs for insurers and patients in everyday cancer care.

To close that gap, the UCLA team conducted a retrospective cohort study built on health insurance claims data. They identified 14,655 patient-drug pairs involving people with cancer who initiated treatment with bevacizumab, rituximab or trastuzumab between 2020 and 2023, a period that spans the market entry of biosimilars for all three drugs. The cohort included patients with commercial insurance as well as those with Medicare-related coverage, and the researchers tracked each patient’s treatment and costs for twelve months after the start of biologic therapy. Patients were sorted into four groups: those who exclusively used a biosimilar, those who exclusively used the originator product, those who switched from the originator to a biosimilar, and those who switched from a biosimilar back to the originator. Monthly insurer payments and patient out-of-pocket costs, calculated as the sum of deductibles, copayments and coinsurance, were compared across the groups after adjusting for differences in patient characteristics and treatment patterns.

The adoption patterns the researchers observed were striking. Among the patient-drug pairs, 59.4 percent of patients exclusively used a biosimilar during the first twelve months of treatment, while 32.5 percent exclusively used the originator. Only 6.9 percent switched from the originator to a biosimilar, and a mere 1.2 percent moved in the opposite direction. In other words, biosimilars captured the market primarily at the point of treatment initiation rather than through conversion of patients who were already mid-course on the branded drugs. That distinction carries practical weight: it suggests that the moment a clinician and patient choose which biologic to start may be the single most important leverage point for expanding the use of lower-cost alternatives, since switching established patients appears to be relatively rare.

The cost differences between the groups were substantial. After adjustment, average monthly payer costs were $8,959 for patients who exclusively used biosimilars, compared with $12,779 for those who exclusively used the originator, a gap of $3,820 every month of treatment. Out-of-pocket savings were smaller in absolute terms but still meaningful: patients on biosimilars paid an average of $118.90 per month versus $158.40 for those on originators, a difference of $39.50 per month. Senior author Tina Shih, director of the Cancer Health Economics Research Program at the UCLA Health Jonsson Comprehensive Cancer Center and professor of Health Economics in the Department of Radiation Oncology, acknowledged the asymmetry but emphasized its human significance. Although the savings were substantially greater for insurers than for patients, she noted, even modest reductions in out-of-pocket costs may be meaningful for people facing the financial challenges of cancer care, since those savings can be directed toward other treatment-related expenses or everyday living costs.

Beyond the patient-level comparisons, the study documented clear market-wide effects of biosimilar entry. The average sales price of the three originator biologics declined by 3.8 percent per year after biosimilars entered the market, evidence that competition pressured the branded products themselves rather than simply carving off a slice of demand. Meanwhile, the originators’ market share fell by roughly 30 percent annually among patients with commercial insurance and 31.5 percent within Medicare Part B. The biosimilars themselves were also becoming cheaper over time: the average sales price of the twelve biosimilar products included in the study declined by 12.4 percent per year, a pattern consistent with intensifying price competition among multiple manufacturers of similar products. Together, these trends indicate that the biosimilar pathway is functioning as intended, reshaping prices across the entire category rather than at the margins.

First author Xiaoyu Liu, a former PhD student in the Department of Health Policy and Management at the UCLA Fielding School of Public Health, framed the findings as timely support for ongoing regulatory efforts. The FDA has continued to take regulatory actions aimed at further unlocking biosimilar competition, Liu said, and the study’s results offer further evidence to support patients, providers and insurers in their consideration of biosimilars. The research team also included Xiaoyi Xu and Z. JohnLu of UCLA. Because the analysis relied on insurance claims rather than clinical records, it speaks primarily to utilization and cost rather than to treatment outcomes, but the regulatory standard for biosimilars, no clinically meaningful differences from the originator, underpins the assumption that the cheaper products deliver equivalent care. The study’s retrospective design also means the associations reflect real-world prescribing behavior rather than a controlled experiment, which is precisely what makes them valuable for policy discussions.

Taken together, the findings sketch a healthcare market in transition. Biosimilars now account for the majority of new treatment starts across three of oncology’s most important biologics, their prices are falling year over year, and their presence is pulling down the prices of the branded originals as well. For the health system, the monthly savings of nearly $4,000 per patient on payer costs represent the kind of aggregate figure that could reshape oncology budgets if adoption continues to climb. For individual patients, the roughly $40 in monthly out-of-pocket relief is modest against the backdrop of cancer’s total financial toll, yet it arrives at a time when financial toxicity affects up to half of American cancer patients and contributes to treatment abandonment and worse outcomes. The study also highlights a practical prescription: because biosimilar uptake happens overwhelmingly at treatment initiation, clinicians, insurers and policymakers who want to widen access to these equally efficacious, lower-cost alternatives should focus their efforts on the first prescription, where the choice between originator and biosimilar is actually made.

Subject of Research: Economic impact of biosimilar competition on cancer biologic drug costs for insurers and patients

Article Title: Cancer biosimilars associated with lower costs for insurers and patients, UCLA study finds

Article References: Cancer biosimilars associated with lower costs for insurers and patients, UCLA study finds. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: biosimilars, cancer biologics, bevacizumab, rituximab, trastuzumab, drug pricing, financial toxicity, JAMA Oncology, UCLA, health economics, Medicare Part B, FDA regulation

The original study, published online in November 2025 in the same journal, used real-world data to track how clinicians and patients actually behaved once a biosimilar alternative to the long-acting insulin analog became available. Real-world data studies of this kind occupy a crucial middle ground between randomized controlled trials and everyday clinical practice. Trials can establish that a biosimilar is therapeutically equivalent to its reference product, but they cannot fully capture how prescribing habits, formulary decisions, rebate negotiations, pharmacy benefit designs, and patient cost-sharing arrangements shape uptake in the messy reality of the American health system. The letter writers engage with exactly this gap, using their comment to probe what the utilization and spending patterns observed in the data actually reveal about whether biosimilar competition is delivering on its economic promise.

Insulin glargine is a long-acting basal insulin analog that has been a cornerstone of diabetes management for millions of people with type 1 and type 2 diabetes. As a biologic medicine, it is produced in living cell systems rather than through straightforward chemical synthesis, which means that even a functionally identical copy cannot be a molecular clone in the way a generic small-molecule drug can. Biosimilars are instead demonstrated to be highly similar to their reference products, with no clinically meaningful differences in safety, purity, or potency. This regulatory framework, established in the United States through the Biologics Price Competition and Innovation Act of 2010, was designed to open the door to competition while maintaining rigorous scientific standards. The arrival of the first biosimilar insulin glargine was therefore watched closely as a test case for whether the framework could translate regulatory approval into real savings at the pharmacy counter.

The stakes of this question are difficult to overstate. Insulin pricing in the United States has been the subject of sustained public outrage, legislative hearings, and policy reform efforts for more than a decade. List prices for analog insulins rose dramatically over the 2000s and 2010s, forcing many patients to ration doses, and the resulting human toll made insulin the emblematic case study of pharmaceutical pricing dysfunction. Biosimilars were held up by policymakers and health economists as one of the most credible market-based levers for change, because unlike price negotiation or direct regulation, they promised to lower prices through the familiar mechanism of competition. Whether that mechanism actually functions for biologics, where switching behavior is slower, prescriber inertia is stronger, and rebate structures can lock in incumbent products, is precisely the empirical question the original study addressed.

The commentary authors, based at institutions in India including Saveetha Medical College and Hospital in Chennai, Graphic Era Hill University in Dehradun, and Dr. D. Y. Patil Medical College in Pune, bring a pharmacoeconomic and global health perspective to the debate. Their letter engages with the methodological choices embedded in the original real-world analysis, and their response reflects a broader international interest in how biosimilar policy performs in the world’s largest pharmaceutical market. The authors report no funding for their work and declare no conflicts of interest, and they note that no new data were generated or analyzed in the comment itself, positioning it squarely as an interpretive and critical contribution to the literature rather than a new empirical study.

One of the central tensions in biosimilar economics is the distinction between list price and net price. When a biosimilar launches at a lower list price than the reference biologic, headlines often celebrate the discount. Yet the net price paid by insurers and patients is shaped by a web of rebates that manufacturers of the originator product offer to pharmacy benefit managers and health plans. These rebate arrangements can make the originator product cheaper for a plan’s formulary than the nominally cheaper biosimilar, a phenomenon that has been documented across several biologic drug classes. Real-world utilization data, such as those analyzed in the original study, are therefore essential for cutting through this opacity, because actual dispensing patterns reveal whether the biosimilar is genuinely displacing the originator or merely occupying a marginal share of the market.

Prescriber and patient behavior adds a second layer of complexity. Decades of research on generic substitution show that even for chemically identical small-molecule drugs, switching rates depend heavily on prescriber trust, electronic health record defaults, pharmacy-level substitution laws, and patient familiarity with a brand name. For biosimilars, the psychological barriers can be even higher, because patients may perceive a biologic copy as somehow less reliable than the original, and clinicians may harbor questions about immunogenicity or device differences even when regulatory data show equivalence. The pace of biosimilar insulin glargine uptake observed in real-world data thus reflects not only price dynamics but also the slow work of building clinical confidence in a new category of medicine.

The letter also situates the insulin glargine case within the wider arc of biosimilar policy. In Europe, where biosimilar uptake was encouraged earlier through national policies, tendering systems, and physician education campaigns, several biologic markets saw substantial price erosion and high biosimilar penetration within a few years of launch. The United States experience has been more uneven, with uptake varying dramatically by drug class, by payer type, and by the design of pharmacy benefit incentives. Comparing the American insulin glargine trajectory against these international benchmarks is one of the analytical lenses through which commentaries like this one help readers judge whether slow uptake is an inevitable feature of a fragmented system or a policy failure that could be corrected with better incentives.

What makes this exchange between the original researchers and the commenting authors scientifically valuable is that it exemplifies the self-correcting machinery of health services research. Real-world data studies rely on large claims databases and utilization records, and the interpretation of spending trends in such data is sensitive to choices about study windows, comparator groups, adjustments for rebate-driven price changes, and the treatment of patients who switch between products. A letter to the editor is a formal venue for surfacing those interpretive choices, questioning whether observed spending changes can be causally attributed to biosimilar entry, and proposing alternative readings of the same evidence. The published reply and the surrounding dialogue allow the field to converge on more robust conclusions than any single analysis could deliver alone.

As insulin policy in the United States enters a new phase, with out-of-pocket caps for Medicare beneficiaries, manufacturer price reductions, and continued biosimilar entries reshaping the landscape, the questions raised in this commentary will only grow in importance. The first biosimilar insulin glargine was a landmark test of whether competition can discipline biologic drug prices, and the real-world evidence examined by Watanabe and colleagues, together with the critical scrutiny it has attracted, suggests that the answer is neither a simple success nor a simple failure. Savings appear to depend on the fine print of formulary design, rebate negotiations, and the behavioral economics of prescribing. For the millions of patients who depend on basal insulin, and for the policymakers designing the next generation of drug pricing reforms, the lesson of this scholarly exchange is that regulatory approval of a biosimilar is only the beginning of the story; the economics of competition must be actively engineered, monitored, and debated in the open, one peer-reviewed analysis at a time.

Subject of Research: Real-world utilization and spending outcomes of the first biosimilar insulin glargine

Article Title: Comment on “Insulin Glargine Utilization and Spending Before and After the First Biosimilar Insulin Glargine: A Real-World Data Study”

Article References: Comment on “Insulin Glargine Utilization and Spending Before and After the First Biosimilar Insulin Glargine: A Real-World Data Study”. (n.d.). https://doi.org/10.1007/s11606-026-10834-4

Image Credits: AI Generated

DOI: 10.1007/s11606-026-10834-4

Keywords: insulin glargine, biosimilars, drug pricing, pharmacoeconomics, type 2 diabetes, real-world data, health policy, biologics, prescription drug spending, Journal of General Internal Medicine, pharmacy benefit design, diabetes care

The research team, led by Sabine Vogler of the Austrian National Public Health Institute, took an unusually broad approach. Previous studies of biosimilar policy typically examined a single country or a handful of biological substances. This analysis covered 27 European countries, including 24 European Union member states, Norway and Switzerland from the European Free Trade Association, and the United Kingdom, and spanned 27 biological active substances comprising roughly 200 individual products. The investigators drew on IQVIA MIDAS sales data covering the period from 2008 through the second quarter of 2024, capturing both hospital and community pharmacy settings for most countries. Cyprus, Denmark, Malta, Iceland and Liechtenstein had to be excluded because no data were recorded for them in the commercial database, a limitation the authors acknowledge, particularly given Denmark’s reputation as a biosimilar success story.

Quantitative analysis was only half the design. The team combined the sales data with a systematic mapping of national policies, compiled through standardised country fiches completed using information from the Pharmaceutical Pricing and Reimbursement Information network, a long-standing collaboration of public authorities responsible for medicine pricing across Europe. Twenty-one of the country fiches were validated by national officials, lending the policy mapping a degree of official confirmation that most cross-country comparisons lack. The researchers then layered on four detailed case studies, tracking market shares before and after specific interventions: switching guidance issued by Italy’s medicines agency, prescribing quotas for insulin glargine in France, and the introduction of pharmacy-level biosimilar substitution in Norway and France.

The policy taxonomy the researchers developed distinguishes supply-side measures, which shape prices and procurement, from demand-side measures, which target the behaviour of prescribers, pharmacists and patients. Supply-side tools include the biosimilar price link, in which a biosimilar’s price is set at a defined percentage below the originator’s; external price referencing, which borrows price benchmarks from other countries; competitive tendering, ubiquitous in hospital procurement; and horizon scanning to prepare payers for upcoming patent expiries. Demand-side tools range from prescribing by International Non-Proprietary Name and formal switching programmes to prescribing quotas, pharmacy substitution and gain-sharing models that return a portion of the savings generated by biosimilar use to hospitals or clinicians. Educational and awareness-raising activities, though present in every country studied, varied so widely in scope that the team excluded them from the comparative analysis.

The mapping revealed how saturated some policy instruments have become while others remain rare. Tendering is universal, applied in all 27 countries, particularly for hospital medicines. The biosimilar price link operates in 21 countries, and 18 countries include biologicals in their reference price systems for reimbursement. On the demand side, 24 countries now oblige, encourage or support prescribers to switch patients from originator biologics to biosimilars, or between biosimilars. Seventeen countries permit INN prescribing for biologicals and 15 impose prescribing quotas. By contrast, pharmacy-level substitution, long a staple of generic medicine policy, exists in only 11 countries, though momentum is building: Norway introduced it in 2021, France in 2022, and Finland, Germany and Switzerland all followed in 2024, typically starting with a narrow list of substances. Gain-sharing models, the study’s standout performer, remain confined to just ten countries.

When the researchers cross-referenced policies with market outcomes, a clear pattern emerged. Countries that had introduced gain-sharing models, encouraged switching, applied a biosimilar price link or imposed prescribing quotas showed, on average, the highest biosimilar market shares. Tendering and tendering-like procedures run by public payers in the outpatient sector were also associated with stronger uptake. The association with gain-sharing is particularly striking because the policy is so uncommon, implemented mainly in higher-income countries with large markets such as France, Germany and the United Kingdom. The authors are careful to stress that their cross-sectional comparison is exploratory and does not establish causation, but the case studies and the wider literature point in the same direction. In Italy, biosimilar market shares rose after the medicines agency published a position paper in March 2018 endorsing the interchangeability of biological medicines and supporting prescriber-initiated switches. In France, where quotas of 20 percent were set for insulin glargine in 2017 and raised to 40 percent in 2021, uptake of the targeted biosimilar increased. In Norway and France, the substances newly subject to pharmacy substitution, insulin glargine and teriparatide in the former and filgrastim and pegfilgrastim in the latter, saw rapid uptake gains after implementation.

The study’s systematic review of 16 empirical evaluations reinforced these findings. Prescribing quotas in Germany and Italy, gain-sharing experiments in France and Ireland, switching programmes in the United Kingdom and Denmark, and tendering systems in Hungary all increased biosimilar uptake in published analyses, with several also documenting substantial savings. One notable exception involved the biosimilar price link in Hungary, which reduced prices without lifting uptake, a reminder that lowering prices alone does not automatically change prescribing behaviour. The literature also emphasised the importance of policy design: gain-sharing works best when the clinical units that generate the savings are the ones that receive them, and price links must create a gap large enough to influence prescriber decisions.

Why do demand-side measures outperform? The authors argue that the principal barriers to biosimilar uptake are behavioural rather than economic. Physicians remain hesitant to switch clinically stable patients, citing lingering concerns about immunogenicity and equivalence, while patients harbour their own fears about safety. Policies that directly address these reservations, through clear regulatory guidance, financial incentives that reward prescribers, and credible communication, appear to provide the leverage that price mechanisms alone cannot. The Norwegian experience with the NOR-SWITCH trial is instructive: prescribing of infliximab biosimilars increased even before the landmark switching study was officially published, once draft findings confirming the safety of the switch circulated informally. The authors suggest that, given the accumulated real-world evidence on switching safety, improving communication should now take priority over commissioning yet more switching studies.

The findings arrive at a critical moment. A next wave of biosimilars is expected to enter European markets in the coming years, challenging some of the highest-priced originator biologics, and the untapped potential identified in low-uptake countries represents billions in possible savings. The study’s message to policymakers is twofold. First, effective interventions usually combine measures, ideally pairing demand-side drivers with supply-side tools such as strategic procurement that considers more than price alone and guards against markets becoming unattractive to suppliers. Second, design and context matter: the same policy instrument can succeed or fail depending on how it is calibrated, how stakeholders are engaged, and how it interacts with other measures already in place. The authors call for continuous monitoring and evaluation as countries implement and refine their policies, noting that even pharmacy substitution, too recent in several countries to show measurable population-level effects, showed promising early signals in the case studies. For a continent united by a single medicines regulator but divided by a fourfold gap in biosimilar uptake, the lesson is that approval was never the hard part; policy is.

Subject of Research: Policy analysis of biosimilar uptake and market shares across 27 European countries

Article Title: Biosimilar uptake policies in Europe: a cross-country mixed-methods policy analysis

Article References: Vogler, S., Habimana, K., Walter, M., Knoll, V., Kuriata, E., Leoszkiewicz, K., Mucha, K., Pelczarska, A., Skassa, E., Petrova, G., Milushewa, P., Mitkova, Z., Tachkov, K., Perelman, J., Alves, J., Santos, C., & Vasconcelos, H. (2026). Biosimilar uptake policies in Europe: a cross-country mixed-methods policy analysis. The Lancet Regional Health – Europe, 70, Article 101868. https://doi.org/10.1016/j.lanepe.2026.101868

Image Credits: AI Generated

DOI: 10.1016/j.lanepe.2026.101868

Keywords: biosimilars, pharmaceutical policy, drug pricing, Europe, market share, tendering, prescribing quotas, gain-sharing, switching, pharmacy substitution, health economics, The Lancet Regional Health

The study, conducted by researchers at Pfizer Japan, IQVIA Solutions Japan, and Pfizer Inc., built a hybrid model combining a decision tree for the initial induction phase with a Markov framework for maintenance and all subsequent lines of therapy. Patients who failed their first advanced therapy were assumed to switch to an alternative agent, then to a basket of remaining drugs, and eventually to best supportive care if they continued to lose response. The simulated population mirrored Japanese trial participants newly starting advanced therapy, with a mean age of 42.4 years and a mean body weight of 59.7 kilograms. Efficacy and safety inputs came from a Bayesian network meta-analysis covering ten advanced therapies, supplemented with Japan-specific costs drawn from a nationwide claims database and adjusted to 2025 price levels.

The economics were evaluated from the perspective of the Japanese payer, with both costs and quality-adjusted life years discounted at an annual rate of 2.0 percent, in line with national health technology assessment guidelines. The willingness-to-pay threshold was set at JPY 7,500,000 per QALY, roughly USD 49,547, the benchmark used in Japan’s system for designated intractable diseases, a category to which ulcerative colitis belongs. Only serious infections were modelled as adverse events, a choice consistent with previous economic evaluations in this therapeutic area, because they drive the greatest costs and quality-of-life impairment while safety profiles across the drug classes remain broadly similar.

The central result was striking in its clarity. Among all 79 sequences evaluated, starting with etrasimod and following with upadacitinib produced the greatest lifetime health benefit, a total of 17.801 quality-adjusted life years. Four strategies anchored the efficiency frontier, the curve tracing the most efficient options at each cost level: infliximab followed by ustekinumab, infliximab followed by etrasimod, infliximab followed by upadacitinib, and etrasimod followed by upadacitinib. Each successive step along the frontier bought more health at an incremental cost-effectiveness ratio comfortably below the Japanese threshold, culminating in etrasimod followed by upadacitinib at JPY 6,684,442 per QALY, which remained cost-effective and delivered the most value overall.

The mechanistic logic behind the winning sequence is instructive. The network meta-analysis showed that upadacitinib, an oral JAK inhibitor, achieved the highest remission and response rates among patients who had already been exposed to advanced therapy, making it a particularly powerful second-line option. Etrasimod, which traps lymphocytes in lymph nodes by modulating the S1P receptor on their surface and thereby blunts intestinal inflammation while preserving systemic immune surveillance, showed favorable efficacy and safety across multiple endpoints in treatment-naïve patients. Pairing the two oral agents in that order therefore maximized cumulative quality-adjusted survival, and etrasimod outperformed ozanimod, its identically priced oral counterpart, on maintenance response, remission, and serious infection rates in the comparative evidence underpinning the model.

Sensitivity analyses revealed where the conclusion could shift. When infliximab and adalimumab biosimilars were introduced into the model, the picture changed materially. Because biosimilar infliximab costs JPY 13,860 per 100-milligram vial compared with JPY 35,981 for the originator, a first-line biosimilar infliximab sequence followed by upadacitinib became the most cost-effective strategy, pushing the etrasimod-upadacitinib combination above the threshold. Yet the authors caution that real-world biosimilar uptake in Japanese ulcerative colitis remains around 20 percent, and a survey found that 85 percent of Japanese inflammatory bowel disease patients were unaware biosimilars even existed. Under Japan’s high-cost medical expense benefit program, out-of-pocket costs are so constrained that patients have little financial incentive to switch.

Other scenario analyses tested alternative assumptions about disease progression and treatment intensity. Allowing dose escalation of tofacitinib, upadacitinib, and ustekinumab during maintenance left etrasimod followed by upadacitinib as the most cost-effective sequence, though with a narrower margin. Assuming patients never transitioned from later-line therapy to best supportive care shifted the optimal sequence to etrasimod followed by ustekinumab. Applying higher colectomy rates, informed by Japanese national database studies, moved infliximab followed by upadacitinib to the top. The fragility of the base-case result was further underlined by the one-way sensitivity analysis, in which placebo-arm maintenance parameters and infliximab’s relative efficacy had the largest influence on the incremental net monetary benefit.

The study carries important caveats that temper any temptation to treat its ranking as clinical gospel. Efficacy estimates derive from a network meta-analysis of trials published through November 2022, and such analyses for ulcerative colitis are known to suffer from heterogeneity in prior biologic exposure, baseline disease activity, and outcome definitions. Real-world evidence, which now exists for several of the agents, was excluded because of incomparability across studies. Serious infections were the only adverse event modelled, leaving unquantified risks such as major cardiovascular events, venous thromboembolism, herpes zoster, and malignancy, factors that matter greatly in real treatment choices. Utility values came largely from non-Japanese populations, and the transition rate from late-line therapy to best supportive care was borrowed from a United States claims database.

There is also the question of who conducted the analysis. All clinical authors are Pfizer employees or contractors funded by Pfizer Japan, and the company financed the research and publication. The acknowledged conflicts do not invalidate the mathematics, but they do mean the framing of etrasimod, a Pfizer drug, as the preferred starting point deserves independent scrutiny, particularly given how sensitive the results were to pricing assumptions around cheaper biosimilars.

For clinicians and policymakers, the study’s value lies less in crowning a single winner than in demonstrating that sequencing choices carry quantifiable economic and health consequences over a lifetime of disease. The authors themselves stress that the findings should complement, not dictate, clinical judgement, alongside patient age, comorbidities, pregnancy plans, and personal preference. As Japan’s ulcerative colitis population grows, having expanded roughly 1.4-fold over eight years, and as real-world data accumulate on the newer oral agents, future updates of this model will be needed to confirm whether the etrasimod-then-upadacitinib pathway truly delivers the best value in everyday practice rather than in simulation.

Subject of Research: Cost-effectiveness modeling of advanced therapy sequences for moderately to severely active ulcerative colitis in Japan

Article Title: Comparative Cost-Effectiveness of Advanced Treatment Sequences for Moderately to Severely Active Ulcerative Colitis in Japan

Article References: Kamei, K., Enami, M., Matsuda, H., Yamagami, K., Dai, Y., Hoshi, M., Law, E. H., & Yuasa, A. (2026). Comparative Cost-Effectiveness of Advanced Treatment Sequences for Moderately to Severely Active Ulcerative Colitis in Japan. Advances in Therapy. https://doi.org/10.1007/s12325-026-03757-3

Image Credits: AI Generated

DOI: 10.1007/s12325-026-03757-3

Keywords: ulcerative colitis, cost-effectiveness, etrasimod, upadacitinib, infliximab, S1P receptor modulators, JAK inhibitors, network meta-analysis, QALY, Japan, biosimilars, treatment sequencing

Insulin glargine is a long-acting basal insulin analog that millions of people with type 1 and type 2 diabetes rely on to control blood glucose around the clock. For years, the market was dominated by a single originator product, making it one of the classic examples of a biologic drug with no direct competition. Biosimilars are copies of biologic medicines that are demonstrated to be highly similar to their reference products in quality, safety, and efficacy, yet without being clinically identical in the way generic small molecules are. Because insulin glargine is manufactured in living systems, its copies cannot be verified by a simple chemical assay; instead, regulators require extensive analytical, pharmacokinetic, and clinical comparative data. That regulatory architecture, designed to protect patients, has also slowed market entry and shaped how payers, pharmacies, and manufacturers respond once a biosimilar finally does arrive.

The clinical foundation for biosimilar insulin glargine was laid in randomized controlled trials conducted well before real-world uptake could be measured. The ELEMENT 2 study, published in Diabetes, Obesity and Metabolism, compared the investigational biosimilar LY2963016 with the originator insulin glargine in patients with type 2 diabetes who were either insulin-naive or already treated with glargine, and found similar efficacy and safety between the two products. Later, the phase III INSTRIDE 2 trial reported comparable results for a different glargine biosimilar candidate, MYL-1501D, versus insulin glargine over 24 weeks in patients with type 2 diabetes. These trials established that biosimilar glargine could, in principle, substitute for the originator without compromising glycemic control or safety. The question the California team pursued was whether that clinical equivalence translated into economic benefit in actual practice, outside the controlled conditions of a trial.

To answer it, the researchers turned to real-world data, examining patterns of insulin glargine utilization and spending across the period surrounding the biosimilar’s debut. Real-world data studies of drug utilization occupy a distinctive methodological niche. Unlike randomized trials, they cannot assign exposure; they must instead reconstruct a credible counterfactual: what would spending and use have looked like had the biosimilar never entered the market? The authors’ response letter makes clear that their analytical strategy leaned heavily on formal time-series methods, the statistical machinery developed for forecasting and intervention analysis in economics and engineering, adapted here to pharmaceutical claims data.

That machinery is not trivial. In their references, the authors cite the foundational work of George Box and Gwilym Jenkins on time series analysis, forecasting, and control, the framework that underlies modern autoregressive integrated moving average modeling. They also cite Rob Hyndman and Yeasmin Khandakar’s automatic time series forecasting tools for the R statistical environment, which allow analysts to fit and select forecasting models systematically rather than by hand. Most tellingly, they cite the 1987 Econometrica paper by Whitney Newey and Kenneth West on heteroskedasticity- and autocorrelation-consistent covariance matrices. That citation signals a careful attention to a problem that plagues interrupted time-series analyses of drug spending: the errors in monthly utilization and spending series are rarely independent, and their variance often shifts over time. Without Newey-West style corrections, standard errors can be badly underestimated, leading researchers to declare statistically significant changes that are really just noise in a serially correlated series.

The core finding that the authors defend in their response is sobering: the arrival of the first biosimilar insulin glargine did not produce the dramatic reduction in spending that generic entry typically delivers. Utilization and spending patterns for insulin glargine, analyzed with these rigorous time-series techniques, did not show the kind of sharp discontinuity that would indicate biosimilar competition reshaping the market. This result stands in stark contrast to the aggregate savings story told by the generic and biosimilar industry itself. The Association for Accessible Medicines, whose 2022 savings report the authors cite, has documented hundreds of billions of dollars in cumulative savings from generic and biosimilar medicines across the United States. The disconnect between that aggregate narrative and the insulin glargine case is precisely what makes the study, and the authors’ defense of it, so consequential.

Why would a biosimilar fail to move the needle where generics so often succeed? The economics of biologics differ in several structural ways. First, a single biosimilar entering a market dominated by one originator creates a duopoly, not the crowded field of many generic manufacturers that drives generic prices toward marginal cost. Second, rebate and formulary dynamics in the United States give pharmacy benefit managers and payers powerful reasons to keep preferred formulary positions with established products whose rebate structures are already negotiated; a biosimilar must often offer deep discounts simply to gain placement, and even then may capture only a fraction of volume. Third, insulin is frequently subject to patient cost-sharing arrangements, deductibles, and assistance programs that decouple the price paid by insurers from the price felt by patients, muting the demand-side response to list price changes. Fourth, switching friction matters: patients stable on a familiar insulin, and prescribers wary of any change in a life-sustaining therapy, may resist substitution even when regulators deem the products interchangeable or highly similar.

The authors’ response letter also addresses the inevitable methodological challenges that such an analysis invites. Real-world claims data are messy: utilization measured in units of volume must be reconciled with spending measured in dollars, and both are affected by changes in formulation sizes, packaging, rebates invisible to the analyst, and shifts in the insured population over time. Time-series intervention analysis requires specifying the date of the intervention, modeling pre-existing trends, and deciding whether to allow gradual or abrupt change. By grounding their approach in the Box-Jenkins tradition and using automatic forecasting procedures to establish a robust pre-intervention baseline, the authors can compare observed post-biosimilar trajectories against what the pre-existing trend predicted. The Newey-West correction then ensures that the statistical inference attached to any deviation is trustworthy. This is the kind of methodological hygiene that separates credible pharmacoeconomic research from casual before-and-after comparisons, and the authors’ willingness to defend it in print reflects the scrutiny that any claim about drug spending inevitably attracts.

The policy implications ripple outward. Insulin pricing has become one of the most visible flashpoints in American health care, prompting state-level copayment caps, federal action on insulin out-of-pocket costs for Medicare beneficiaries, and intense scrutiny of the rebate system. If biosimilar entry alone cannot discipline prices in this market, then the policy toolkit may need to focus on the intermediaries: the formulary and rebate negotiations that determine which products patients can actually access, and the cost-sharing design that determines what they pay at the counter. The insulin glargine experience suggests that simply adding a cheaper copy to the market is not sufficient; the structural incentives of the supply chain must be aligned so that savings reach patients rather than being absorbed in negotiations upstream.

There is also a forward-looking dimension. Insulin glargine was the first biosimilar in this therapeutic class, but it will not be the last biosimilar opportunity in diabetes care, and the lessons from this real-world analysis will inform expectations for every subsequent biologic that loses exclusivity. Pharmacists, health economists, and statisticians such as Watanabe, Strand, and Shen are building the evidentiary base that policymakers will need: careful, transparent, statistically defensible measurements of what actually happens when biosimilars enter complex markets. Their response letter, published in the Journal of General Internal Medicine, is a reminder that in pharmacoeconomics, as in clinical medicine, the details of method determine the credibility of the conclusion. If the United States wants biosimilars to deliver on their promise of affordable biologics, the insulin glargine experience shows that market entry is only the first step; the harder work lies in redesigning the incentives that decide whether a cheaper, clinically equivalent medicine actually changes what patients pay.

Subject of Research: Real-world utilization and spending outcomes for insulin glargine following the introduction of the first biosimilar insulin glargine in the United States

Article Title: Authors Respond: Insulin Glargine Utilization and Spending Before and After the First Biosimilar Insulin Glargine: A Real-World Data Study

Article References: Watanabe, J. H., Strand, M. W., & Shen, W. (2026). Authors Respond: Insulin Glargine Utilization and Spending Before and After the First Biosimilar Insulin Glargine: A Real-World Data Study. Journal of General Internal Medicine. https://doi.org/10.1007/s11606-026-10837-1

Image Credits: AI Generated

DOI: 10.1007/s11606-026-10837-1

Keywords: insulin glargine, biosimilars, drug spending, pharmacoeconomics, type 2 diabetes, real-world data, time-series analysis, drug utilization, Journal of General Internal Medicine, health policy, insulin pricing, biologics