Biosimilars And Follow-On Products In The United States: Adoption, Prices, And Users

Lowering drug prices is a frequent topic of discussion in the US, and lawmakers have recently proposed several pieces of related legislation.¹ In the months before leaving office, the Trump administration issued multiple executive orders and proposed rules related to drug pricing.^2,3 The vast majority of Americans consider lowering prescription drug pricing and broader health care spending to be among their top policy issues.⁴

One opportunity for cost savings involves encouraging competition in biopharmaceutical markets after exclusivity expiration (that is, after patent terms and regulatory exclusivities have ended). For generic drugs, the 1984 Drug Price Competition and Patent Term Restoration Act (commonly called the Hatch-Waxman Act) is estimated to have saved around $1.8 trillion during the period 2008–17 by creating a mechanism for rapid and extensive postexclusivity competition for branded small molecule drugs in the US.⁵ However, the provisions of the Hatch-Waxman Act do not apply to a key class of drugs called biological products, also known as biologics.

Biologics are complex large molecules and are typically difficult to characterize completely.⁶ Unlike common small molecule drugs such as antihistamines or statins that are chemically synthesized, biologics are products such as vaccines, monoclonal antibodies, gene therapies, and allergenics that are composed of biological material (typically nucleic acids, amino acids, proteins, and cells). As of 2015 they represented 38 percent of US drug spending, as well as 70 percent of drug spending growth between 2010 and 2015, although they were used by just 1–2 percent of the population.⁷ Given biologics’ disproportionate contribution to drug spending, successful policy efforts to stimulate competition in these product markets are likely to have a meaningful impact on overall US drug spending growth.

Because the Hatch-Waxman Act did not apply to biologics regulated under the Public Health Service Act of 1944, Congress enacted the Biologics Price Competition and Innovation Act (BPCIA) of 2009 as part of the Affordable Care Act. This legislation established an “abbreviated licensure pathway” for biosimilars and interchangeable products—the biologic analogue to generics—to compete with branded biologic reference products.⁸ Five years later, in 2015, the first BPCIA biosimilar product received a Food and Drug Administration (FDA) license. Some complex, biosimilar-like products were previously approved via the traditional biological product approval pathway [351(a)] or via new drug applications [505(b)(2)] or abbreviated new drug applications [505(j)].⁹

The BPCIA defines a biosimilar as “a biological product that is highly similar to and has no clinically meaningful differences from an existing FDA-approved reference product”⁶ (that is, it possesses essentially the same molecular composition as the reference product and produces comparable clinical effects). Unlike generics, biosimilars are not necessarily designated as fully interchangeable, meaning that only the prescriber, not pharmacists, can substitute a biosimilar for the reference product, which presents a competitive barrier. Providers may be unfamiliar with biosimilars, adding to the challenge of substituting them for reference products. An interchangeable biosimilar would need to further demonstrate low immunological or other risk with switching for the reference product; for example, this could be done through additional clinical trials. As of April 15, 2021, no US interchangeable biosimilars had been licensed.

To date, the pace and extent of US biosimilar adoption, the impact of biosimilar competition on prices and quantities of products used, and differences across distinct payers with differing incentive structures have not been well documented. (One recent study, however, has documented overall price reductions of 5.4–7.0 percentage points associated with each additional competitor in seven biosimilar markets.)¹⁰ We present data on these topics and discuss how the emerging US biosimilar market compares with US generic drug markets. The results reported here provide both novel insights into the early years of biosimilar and related follow-on competition in the US and early evidence to inform policy discussions and actions to enhance the achievement of the BPCIA’s goals.

Study Data And Methods

Our data include the US biologic drug classes (and one complex molecule) that experienced follow-on entry during 2005–19. For simplicity, we collectively refer to these as biosimilars/follow-on products and differentiate between the subset of these products entering the market through the 351(k) process established by the BPCIA versus those approved via other FDA regulatory pathways. The products not approved through the 351(k) pathway were selected for inclusion because they are considered biologics and biosimilars by non-US regulators or were a so-called Section 505 drug “deemed to be a license” under Section 351.¹¹ For example, enoxaparin sodium is defined as a complex molecule rather than a biologic in the US. However, because it is considered a biosimilar in the European Union (EU), we include it in our sample.^12,13 Because enoxaparin sodium was approved in the US as a generic drug and is sold primarily through retail pharmacies, it provides unique insights into potential interchangeable biologic drug competition.

Sample Selection

We focused on the set of biosimilars/follow-on products launched in the US during 2005–19, as shown in online appendix A.¹⁴ We collected monthly (US dollar) sales and quantity data for biosimilars/follow-on products and their reference products during this period.

Data Sources And Preparation

We obtained FDA and European Medicines Agency (EMA) approval dates for each product.^15,16 Monthly quantity, sales, and price data were provided by IQVIA for each product National Drug Code (NDC) at the sales channel level (for example, clinics, nonfederal hospitals, long-term care facilities, and so on) from IQVIA’s National Sales Perspective (NSP) data set from January 2005 through December 2019. Monthly quantity, wholesale acquisition cost list price, and sales data for NDCs were obtained from IQVIA’s DDD data set beginning in January 2011. IQVIA also provided US launch dates for each biosimilar/follow-on product. Appendix B provides definitions of the disaggregated levels at which data were collected and detail on quality assurance tests performed.¹⁴

Several data transformations were required for analysis. To enable unit comparability, we calculated product units (in milligrams or units) on the basis of the active pharmaceutical ingredient for each product (NDC) by multiplying the product strength by the number of units. We calculated biosimilar/follow-on product volume market share for each product class and average price per unit (total dollar sales divided by units). To understand competition over time, we calculated time since initial biosimilar/follow-on product launch and months of biosimilar/follow-on product competition. To explore possible usage differences among drug purchasers facing different reimbursement incentives, we used the disaggregated data to create groups that reflect nine payer incentive types: 340B facilities, non-340B hospitals, those engaging in bundling or treating end-stage renal disease, chain pharmacies, non–chain pharmacies, federal facilities, integrated health systems (such as Kaiser Permanente), nursing homes, and fee-for-service or outpatient facilities. Detailed definitions of each payer incentive type are in appendix C.¹⁴

Analytic Implementation

We calculated unit sales and the market share of reference-product units in each product class for all sample products at the levels of total US, channel, and payer incentive type. In addition, we calculated a price ratio, defined as the ratio of average market price to the price before biosimilar/follow-on product entry in each drug class in each month after biosimilar/follow-on product entry. This price ratio was calculated as the weighted average of the unit prices of all reference products and biosimilar/follow-on products sold divided by average reference-product price in the month preceding initial biosimilar/follow-on product entry.

In regression analyses including data from all products, we explored predictors of differences in follow-on product take-up, where the key dependent variables are the reference-product volume share of the product class market and price ratio. The key explanatory variables are linear measures of elapsed months since initial biosimilar/follow-on product entry, “later” biosimilar/follow-on product entry (that is, in 2018 or 2019 versus before 2018), and use of the BPCIA regulatory pathway (that is, using the 351(k) process or BPCIA versus other pathways)].

In robustness analysis, we also controlled for binary indicators for oncology products, for chronic disease drugs, and for a cubic measure of elapsed months since biosimilar/follow-on product entry. In addition, we explored predictors of the price ratio, using the same set of explanatory variables and robustness tests. To ensure the robustness of our results and explore product heterogeneity, we limited the sample to specific time horizons beyond the entry of the first biosimilar/follow-on product, with the main models including data from all products. Supplementary regression analyses used the same predictors as above but separated the sample into individual product classes (appendix D).¹⁴ We grouped channels and payer incentive types that were less than 5 percent of volume and not one of the top three channels or payer incentive types for a product class into an “other” category (appendix B).¹⁴

Finally, we calculated daily volumes of reference products in each class by sales channel and payer incentive type and present these disaggregated utilization data graphically.

Limitations

The relatively short US biosimilar/follow-on product marketing period was the largest limitation of this study; half of our sample products were launched in 2018 or later. The EU’s biosimilar history is nearly twice as long as that of the US and has been studied in more detail.^17,18 Given the relatively short time horizon, our results might not be representative of future market dynamics that may evolve as patients, health care providers, regulators, and insurers gain experience with biosimilars and as interchangeable products enter the market.

The availability and completeness of price data further limited this study. The NSP data set provides national average invoice prices but does not include rebates or other “off-invoice” payments. Nor does it include data on downstream channel price markups or patient payments from copayments or coinsurance. The DDD data set provides list prices (wholesale average cost), which are different from manufacturers’ ultimate invoice prices. Thus, the impact of biosimilar/follow-on product competition on prices reported here may misstate the true impact of biosimilar/follow-on product competition on manufacturers or primary payers.

Reporting restrictions are also a known limitation of the DDD data set. Notably, Kaiser Permanente, a significant early biosimilar adopter,¹⁹ requests that its primary suppliers restrict reporting of sales to its outlets. This likely means that the DDD-based analyses underestimate the speed and size of biosimilar uptake both in the integrated health system payer incentive type and overall.

In addition, most current biosimilars/follow-on products and their reference products are administered by physicians and therefore circumvent retail pharmacies, limiting comparison to generics. Differences in supply chains, discounting, and rebate practices for physician- versus patient-administered drugs may result in uptake and pricing differences. Interchangeable products entering the market may further alter competitive dynamics.

Study Results

Our analysis sample contained ten reference-product classes with twenty-three biosimilar/follow-on products. For a detailed summary, see appendix A.¹⁴ As of the end of 2019, twenty-six biosimilars and fourteen other follow-on products had been approved in the US, with twelve of each having been launched. Because rituximab experienced its first biosimilar/follow-on product in November 2019, this drug class was excluded because of a lack of availability of meaningful data. The remaining eleven biosimilars approved via the BPCIA pathway and twelve follow-on products approved via alternative pathways were included in the analysis sample. Of the alternative-pathway follow-on products, three used the 505(b)(2) pathway, eight were approved through abbreviated new drug applications, and one used the 351(a) pathway.²⁰ For all biosimilars/follow-on products, the FDA-approved indications were the same as those of their respective reference products. Up to 180 months of data were available for some product classes, with an NSP average of ninety-two months (median, sixty-six months) of biosimilar/follow-on product experience per class.

Individual Products: Market Share And Prices

Exhibit 1 displays market-share changes for biologic reference products by product class from one year before to up to four years after initial biosimilar/follow-on product entry. (Additional months of data are available for some products; however, market shares tend to level out over time.) By the end of 2019 reference-product market shares in our sample ranged from 8 percent to 87 percent, with a median of 77 percent (appendix A).¹⁴

SOURCE Authors’ analyses of data from the IQVIA National Sales Perspective data set. NOTES The launch dates for the first biosimilar/follow-on product for each product class are as follows: bevacizumab, July 2019; enoxaparin sodium, July 2010; epoetin alfa (Epogen + Procrit), September 2018; filgrastim, November 2013; infliximab, November 2016; insulin glargine, December 2016; insulin lispro, March 2018; somatropin, January 2007; trastuzumab, July 2019; and pegfilgrastim, July 2018. “Late entrants” are product classes that had their first biosimilar/follow-on product enter the market in 2018 or 2019. ^aBiosimilar or follow-on product approved via the Biologics Price Competition and Innovation Act of 2009.

Product classes that faced earlier biosimilar/follow-on product entrants display steady monotonic declines in reference-product market shares. The two product classes with the longest competitive history—somatropin (example indications: growth hormone deficiency and Prader-Willi syndrome) and enoxaparin sodium (example indications: prophylaxis of deep vein thrombosis and acute deep vein thrombosis)—eventually experienced relatively stable reference-product market share, albeit at vastly different levels. Product classes facing later (2018 or beyond) biosimilar/follow-on product entry experienced more rapid declines in reference-product market share than product classes with earlier entrants. This pattern is especially notable for the two most recent product classes with biosimilars: bevacizumab (example indications: glioblastoma and colorectal, lung, kidney, cervical, or ovarian cancer) and trastuzumab (example indications: breast, stomach, or esophageal cancer).

Exhibit 2 presents price ratios for biologic reference products by product class from one year before to four years after initial biosimilar/follow-on product entry. As in the market-share analysis shown in exhibit 1, the price ratios observed in most later-entrant classes have steeper declines than those of classes with earlier biosimilar/follow-on product entry. For example, the price ratios for trastuzumab, bevacizumab, and pegfilgrastim tend to be lower than those of most of the other products; these three reference product classes all saw their first biosimilar launch in the final two years of our period of observation. Meanwhile, somatropin (the product class with the earliest biosimilar/follow-on product) experienced increases in its price ratio over time, although unit prices of the follow-on product remained significantly lower than those of the reference product throughout all years. See appendix E for these results.¹⁴

SOURCE Authors’ analyses of data from the IQVIA National Sales Perspective data set. NOTES The calculation of the price ratio is described in the text. The launch dates for the first biosimilar/follow-on product for each product class are in the notes to exhibit 1. “Late entrants” are product classes that had their first biosimilar or follow-on product enter the market in 2018 or 2019. ^aBiosimilar or follow-on product approved via the Biologics Price Competition and Innovation Act of 2009.

The enoxaparin sodium class, with its early entrants, presents a notable exception to the finding that later entrants experienced steeper declines in market share and prices, on average. Enoxaparin sodium experienced the largest decline in both reference-product market share and its price ratio. Notably, this product was approved under an abbreviated new drug application and sold as a substitutable generic drug in the US but is considered a biosimilar in the EU. As the only product in our sample that was interchangeable by pharmacists, it is thus a potential benchmark for the competitive dynamics one might expect from a fully interchangeable biosimilar. Appendix E presents further detail on market share and use for individual biosimilar/follow-on products.¹⁴

Overall Market Share And Prices Ratios: Regression Analysis

Exhibit 3 presents the results of our ordinary least squares regression. More detail on regression models is in appendix F.¹⁴ All models were estimated using data after biosimilar/follow-on product entry. Models 1–3 show the decline in reference-product volume market share on competitor entry, using the NSP data set. Model 1 indicates that, on average, each additional month of biosimilar/follow-on product competition was associated with a 0.462-percentage-point decline in reference-product market share, for an average increase in biosimilar/follow-on product market share of 5.54 percentage points per year (percentage-point change not shown). Model 2 considers differences among product classes with earlier versus later entrants. The coefficient on the “later entrant” variable indicates that, on average, classes with later biosimilars/follow-on products had higher reference-product market shares, although this result is mechanical: By definition, these products have had fewer months of biosimilar/follow-on product competition at every point in time. The estimated coefficient of interest in model 2 is on the interaction term, which indicates that in later-entrant product classes, each month of biosimilar/follow-on product competition was associated with an additional 0.287-percentage-point decline in reference-product market share (exhibit 3). In other words, markets with more recent biosimilar/follow-on product competition experienced more rapid declines in reference-product market share—on average, an additional 3.44 percentage points per year (data not shown)—mirroring the graphical trends seen in exhibit 1.

Model 3 considers differences between classes with competitors approved via the BPCIA versus other regulatory pathways. Here, the BPCIA indicator shows that, on average, product classes with biosimilars approved via the BPCIA have greater reference-product market share, but that result is also mechanical: In nearly all cases, non-BPCIA product classes experienced follow-on product entry several years before the first BPCIA products were approved. Thus, in our sample (and at every point in time), product classes affected by the BPCIA had fewer months of observed biosimilar/follow-on product competition than classes that were not affected by the BPCIA. As in model 2, the key coefficient of interest in model 3 is therefore the interaction term, which indicates that after the launch of the first biosimilar/follow-on product, product classes with biosimilars approved via the BPCIA saw an additional 0.665-percentage-point decline in reference-product market share per month (exhibit 3), which is the equivalent of an additional 7.98 percentage points per year, on average (data not shown). This highlights that BPCIA-facilitated competition led to more rapid declines in reference-product market shares compared with competition facilitated via other pathways.

Models 4–6 of exhibit 3 illustrate the evolution of the price ratio after biosimilar/follow-on product entry. Model 4 shows that, on average, each additional month of biosimilar/follow-on product competition was associated with an increase in the price ratio; however, this overall time trend was driven entirely by somatropin, as seen visually in exhibit 2. Following the same logic as in model 2, we report in model 5 the differences for product classes with later versus earlier entrants; the coefficient on the interaction term indicates that being a late-entrant product class was associated with a 0.810-percentage-point average monthly decline in the price ratio, offsetting the impact of the positive coefficient on the overall price time trend. Appendix E contains additional detail on average price increases seen in all markets leading up to biosimilar/follow-on product entry and subsequent price changes in reference-product and biosimilar/follow-on product prices.¹⁴

Model 6 reports differences among biosimilars/follow-on products approved via different regulatory pathways. In this model the interaction term is again the coefficient of interest and shows that having reference products with competitors approved via the BPCIA was associated with an additional 1.02-percentage-point monthly decline in the price ratio after biosimilar/follow-on product entry. Thus, product classes with competitors approved via the BPCIA saw steeper price declines. The negative coefficients on both interaction terms are twice the magnitude of and opposite in direction to the coefficient on the overall time trend, such that, on average, in a product class with one or more later entrants, biosimilars approved via the BPCIA would be expected to see declining price ratios over time.

All regression models are qualitatively robust to controlling for binary indicators for oncology products, for chronic disease drugs, and for a cubic measure of elapsed months since biosimilar/follow-on product entry (appendix G).¹⁴

Appendix D presents results from exhibit 3 by individual product class.¹⁴ These results indicate that the average time trend in the decline of reference product share varied by market, ranging from 0.34 percentage points per month for infliximab (example indications: rheumatoid arthritis and psoriatic arthritis) to 2.4 percentage points for bevacizumab. The monthly time trend for price ratios varied from +0.69 percentage points for somatropin to –1.1 percentage points for trastuzumab.

Channel And Payer Incentive Type: Utilization

Exhibits 4 and 5 provide illustrative examples of the average daily volume in standardized units of reference products sold through different channels and payer incentive types for a sample product (filgrastim). Similar graphs for the remaining products are in appendix E.¹⁴ The top three channels and payer incentive types by product-class volume and any additional channels or payer types with at least 5 percent of the volume for each of the product classes were included in these figures.

SOURCE Authors’ analyses of data from the IQVIA National Sales Perspective data set. NOTES For illustrative purposes, one sample product (filgrastim) is presented. Graphs for the additional products in the analysis sample are in appendix E (see note 14 in text). Only the top three channels (or those that had greater than 5 percent market share) are displayed. Averages in daily volume were calculated to account for the IQVIA calendar (appendix B). Best fit lines represent the best fit values from ordinary least squares regression of the data shown (dots). The best fit lines are estimated separately in the periods before versus after entry of the first biosimilar/follow-on period and independently for each channel.

SOURCE Authors’ analyses of data from the IQVIA DDD data set. NOTES For illustrative purposes, one sample product (filgrastim) is presented. Graphs for the additional products in the analysis sample are in appendix E (see note 14 in text). Only the top three payer incentive types (or those that had greater than 5 percent market share) are displayed. Averages in daily volume were calculated to account for the IQVIA calendar (appendix B). Best fit lines represent best fit values from ordinary least squares regression of the data shown (dots). The best fit lines are estimated separately in the periods before versus after entry of the first biosimilar or follow-on product and independently for each payer incentive type.

Exhibit 4 shows that the most common channels in which filgrastim was sold were clinics, nonfederal hospitals, and the mail. In the filgrastim market there were clear declines in reference-product use in all three major channels after the biosimilar/follow-on product entered the market.

Exhibit 5 illustrates the payer incentive types with the greatest shares of volume for filgrastim (non-340B hospitals, outpatient, and non–chain pharmacies). In the filgrastim market there were declines in reference-product volume for all three of the largest payer incentive types, with the most dramatic declines seen for outpatient and non-340B hospitals.

Although filgrastim reveals declines in reference-product use across multiple channels and payer incentive types, there was significant heterogeneity in market dynamics after biosimilar/follow-on product entry across other product classes, channels, and payer incentive types. Some channels and payer incentive types appear to be more aggressive adopters of biosimilars/follow-on products, whereas others are less so. In addition, the channels and payer incentive types in which most reference-product volume is sold vary greatly across product classes. See appendix H for additional information about reference-product market share by channel and payer incentive type and total-product-class volume expansion or contraction.¹⁴

Discussion

In all product classes, the market share of reference products declined, on average, with time since biosimilar/follow-on product launch.

To date, US market experience with biosimilars/follow-on products has been brief, with half of the ten key product classes seeing market entry in 2018 or later. Nevertheless, early data are informative for guiding future policy: In all product classes, the market share of reference products declined, on average, with time since biosimilar/follow-on product launch. Despite this apparent increase in competition, some reference products maintained their existing market share. Indeed, in the last month of 2019 the market share of reference products in our sample ranged from 8 percent to 87 percent. Although biosimilar/follow-on product take-up was gradual (especially for earlier entrants) and was not as large as what is typically seen in small molecule generic drug markets, it follows a similar trend to that observed among generic drugs in the years that immediately followed the passage of the Hatch-Waxman Act.²¹ Notably, the decline in reference-product market share occurred even though biosimilars/follow-on products—unlike their small molecule generic counterparts—are not designated by the FDA as interchangeable. Because of this distinction, only one of the products studied here (enoxaparin sodium) was eligible for automatic pharmacy substitution for the reference product.

Moreover, exhibits 1 and 2 indicate that product market shares and price ratios for reference products facing later entrants and BPCIA biosimilars/follow-on products declined more steeply compared with other products approved earlier or through other pathways. Given the limited number of observations for the more recent market entrants, future research will provide important insights as the adoption of biosimilar/follow-on products evolves. Nevertheless, our results provide some early data that recent biosimilar/follow-on product entrants have experienced more rapid take-up, suggesting potential learning about these products’ perceived safety and value by physicians, payers, and patients. Future research should explore the potential strategies (for example, extended patent litigation or increased bundling) of reference-product manufacturers, which may respond differently to biosimilar/follow-on product entry depending on the makeup of their overall product portfolios and other factors.

Notably, biosimilars/follow-on products are not always available in all reference-product package sizes, modalities, or strengths. These limitations may inhibit their adoption by physicians and patients in some circumstances. For example, when the biosimilar drug Retacrit entered the market in 2018, it shipped in just nine NDCs compared with the twenty-six offered by the reference product, Procrit. Similar patterns (more NDCs among reference products) exist across all other product classes except for infliximab, in which both the reference products and biosimilars/follow-on products each ship in only one NDC (data not shown).

The coming years will inform whether the steep decline in reference-product market share observed in later-entrant product classes (exhibit 1) represents a new normal for a maturing biosimilar marketplace, as well as how far reference-product market shares may ultimately decline. It will also be crucial to analyze whether future biosimilars/follow-on products continue to have greater price declines as the number of competitors increases and as additional product classes experience biosimilar/follow-on product entry, as many have noted that to date, early list price discounts for biosimilars/follow-on products have been meaningfully smaller than what is seen in generic markets.^22,23 In addition, “biobetter” reformulations (that is, differentiated biologics in the same product class that allegedly embody some improvement over the original biologic and its biosimilars) of both reference products and biosimilars/follow-on products may play a role. For example, in mid-2020 Amgen highlighted growth in the use of a reformulation of its pegfilgrastim product that facilitated fewer clinic visits during the early months of the COVID-19 pandemic.²⁴

To the extent that the enoxaparin sodium product class can be considered a proxy for competition among interchangeable biologic products, the gap between the price reductions seen in that product class versus all other biosimilar/follow-on product classes suggests that substantial price declines may occur with interchangeability and longer periods of competition. Over long periods, other factors that affect prices are also likely to come into play. These include additional competitors entering the market, the desire or need for manufacturers to recoup development costs, and the maturation of the biosimilar landscape and public knowledge thereof. (Notably, after nearly a decade of follow-on product competition, the 2019 price of enoxaparin sodium had declined to only 19 percent of the price of the reference product before follow-on product competition, relative to a median of 91 percent among the remaining nine newer, noninterchangeable product classes [results not shown].)

Conclusion

Further policies to encourage more robust, broad competition may be warranted to achieve maximum biosimilar competition and thus savings.

Data from the early years of biosimilar/follow-on product competition in the US provide insight into how much these products were used, and by which types of buyers. Concerns have been voiced that this competition has not reduced prices rapidly or deeply.²⁵ Biosimilar market optimists have counseled patience to allow competition to develop and markets to mature.²⁶ The results of this study suggest that the introduction of biosimilars is associated with declines in both reference-product market share and prevailing prices in drug classes with biosimilar/follow-on product competition. Further, product classes that experienced more recent biosimilar/follow-on product entry saw more rapid declines in reference-product market shares and prices. As with small molecule generic drugs, price declines are likely to continue as additional competitors arrive. Further policies to encourage more robust, broad competition may be warranted to achieve maximum biosimilar competition and thus savings. It will be useful for future research to identify and quantify factors affecting the differential rates of biosimilar/follow-on product diffusion across product classes, sales channels, and payer incentive types.

Additional topics meriting further study include factors affecting the number of biosimilar/follow-on product competitor entrants in each class, whether manufacturers choose to bring them to market as biosimilars or as “biobetters,” determinants of delays between FDA approval and product launch (including litigation), and characteristics of product classes in which overall volume increases or decreases after biosimilar/follow-on product entry.

Although open questions remain, early data on biosimilar/follow-on product competition in the US reveal both growing adoption as well as heterogeneity among buyers, indicating that more targeted polices, incentives, and information campaigns may be helpful in stimulating future use. Future research should explore these dynamics over longer periods and as additional biosimilars/follow-on products enter the US market. Such research will help facilitate evidence-based public policies in the future.

ACKNOWLEDGMENTS

This research is based on a research study commissioned by the Office of the Assistant Secretary for Planning and Evaluation (ASPE), Department of Health and Human Services (HHS). Ariel Dora Stern is supported by a Junior Faculty Fellowship from the Kauffman Foundation. The other authors report no additional financial support for this research. Any opinions presented in this article are those of the authors only and do not represent the views of their employers. Mark Trusheim reports receiving other income from Co-Bio Consulting LLC. Amber Jessup’s contributions to study design and writing primarily occurred when she worked at ASPE. The views expressed in this article are those of the authors and do not necessarily represent those of the Office of the Assistant Secretary for Planning and Evaluation or the Office of Inspector General, Department of Health and Human Services.

NOTES

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