Skylar Jeremias is the Managing Editor for The Center for Biosimilars and The American Journal of Managed Care (AJMC).

Skylar Jeremias

August 2025 proved to be another dynamic month for the biosimilar landscape, characterized by significant financial milestones, new product launches, reinforcing clinical data, and ongoing battles over market access. These developments underscore the growing impact of biosimilars on health care affordability and treatment options, even as persistent challenges continue to shape their adoption.

August 2025 highlights significant advancements in biosimilars, showcasing financial successes, new product launches, and ongoing challenges in market access.

, showcasing a remarkable financial turnaround.

 The Iceland-based biotech company swung from a $153.5 million net loss in the first half of 2024 to a 

 for the same period in 2025. This success was largely fueled by a 

more than 200% year-on-year increase in product revenues

, reaching $204.7 million, and marking the company's first-ever quarterly positive cash flow from operations. 

Key drivers included the strong commercial performance of its high-concentration adalimumab biosimilar, Simlandi (marketed as Hukyndra in Europe), and its ustekinumab biosimilar, Selarsdi (Uzpruvo in Europe). 

Selarsdi, which gained interchangeable status from the FDA in April 2025, achieved more than 20% of the overall Stelara market share in the US by July 2025. Alvotech is also advancing its pipeline, with biologics license applications for proposed denosumab and aflibercept biosimilars accepted by the FDA, and its aflibercept biosimilar, Mynzepli, recently secured European approval.

Accord BioPharma commercially launched Imuldosa

, its biosimilar to Stelara, approved for various indications including plaque psoriasis, psoriatic arthritis, Crohn disease, and ulcerative colitis.

 Accord BioPharma priced Imuldosa at the 

 among branded ustekinumab biosimilars and offered a $0 co-payment program for eligible patients, aiming to expand access to cost-effective biologic therapies.

Clinical Data Reinforce Biosimilar Equivalence and Safety

Several studies published in August bolstered the scientific evidence for biosimilars. A 

year-long phase 3 clinical trial in Poland

, to the reference product Actemra/RoActemra for rheumatoid arthritis (RA).

comparable efficacy, safety, and immunogenicity

, even for patients who switched from the originator biologic, with consistent disease activity scores and no new safety concerns identified. This adds to the growing confidence in biosimilars for RA management, alongside other FDA-approved tocilizumab biosimilars like Tofidence and Tyenne.

equivalence of denosumab biosimilar LY01011 to the reference product Xgeva

 for treating bone metastases in solid tumors.

 LY01011 demonstrated similar efficacy in reducing bone metabolism biomarkers, comparable safety profiles, and a lack of unexpected adverse reactions across 850 patients. This evidence supports the use of denosumab biosimilars, such as Wyost/Jubbonti, which were approved in the US in March 2024. Long-term safety data also emerged for Sandoz’s biosimilar filgrastim. 

10-year prospective follow-up of 244 healthy stem cell donors

 who received Zarzio (marketed as Filgrastim Hexal in Germany) 

 for hematopoietic stem and progenitor cell mobilization.

 While most donors experienced adverse events during initial mobilization, serious adverse events documented over the decade were not deemed related to the biosimilar filgrastim, and donors maintained superior physical health scores. This study reinforces the established safety profile of filgrastim biosimilars, including Zarxio (filgrastim-sndz), which was the first FDA-approved biosimilar in the US in 2015.

 found comparable outcomes between etanercept biosimilars (Brenzys or Erelzi) and the originator, Enbrel

, for patients with rheumatoid arthritis.

 The analysis revealed no significant differences in time to first remission or sustained remission rates, aligning with findings from randomized controlled trials and European registry data. This highlights the clinical interchangeability of these products, in stark contrast to the 

delayed market entry of etanercept biosimilars in the US due to ongoing patent litigation

Battles Over Market Entry and Access Innovation

The ongoing challenge of patent disputes continues to affect biosimilar market entry. Genentech and Hoffman-La Roche initiated the 

first patent infringement case (BPCIA complaint) concerning a pertuzumab biosimilar

, filing against Shanghai Henlius Biotech and Organon.

 The complaint alleges infringement of 24 patents related to Genentech’s originator, Perjeta, following a pattern of litigation that has previously delayed market launches for other biosimilars.

However, innovative strategies are emerging to enhance access. 

MedImpact Holdings announced plans to provide access to an unbranded ustekinumab-aekn biosimilar

. This unbranded interchangeable biosimilar to Stelara is anticipated to be available at a significantly lower cost, aiming to bypass traditional supply chain costs, enhance price transparency, and reduce reliance on rebates, thus offering a more affordable treatment option for patients.

Despite the clear benefits, challenges in biosimilar adoption persisted. A comprehensive analysis of primary care prescribing data from 2020 to 2024 revealed that 

low prices failed to boost insulin glargine biosimilar uptake

 Even after the MHRA declared all biosimilars interchangeable with their reference products in 2022, originator Lantus continued to dominate prescriptions and, by 2024, became the least expensive option in all 4 UK nations. 

Biosimilars like Abasaglar and Semglee achieved only modest market shares (eg, 24% in England and Scotland, 5% in Northern Ireland, 11% in Wales). Key barriers identified include Lantus's price reductions, prescriber inertia, and national prescribing guidelines that require prescribers to initiate brand switching.

1. Jeremias S. Alvotech reports record-breaking first half of 2025 amid strong biosimilar sales. The Center for Biosimilars

. August 27, 2025. Accessed September 2, 2025. 

https://www.centerforbiosimilars.com/view/alvotech-reports-record-breaking-first-half-of-2025-amid-strong-biosimilar-sales

2. Jeremias S. Litigation, launch, and lower costs: 3 big moves in the US biosimilar space. The Center for Biosimilars. August 19, 2025. Accessed September 2, 2025. 

https://www.centerforbiosimilars.com/view/litigation-launch-and-lower-costs-3-big-moves-in-the-us-biosimilar-space

3. Jeremias S. Year-long phase 3 study confirms tocilizumab biosimilar comparability with Actemra. The Center for Biosimilars. August 6, 2025. Accessed September 2, 2025. 

https://www.centerforbiosimilars.com/view/year-long-phase-3-study-confirms-tocilizumab-biosimilar-comparability-with-actemra

4. Santoro C. Denosumab biosimilar LY01011 shows equivalence to reference product for bone metastases. The Center for Biosimilars. August 14, 2025. Accessed September 2, 2025. 

https://www.centerforbiosimilars.com/view/denosumab-biosimilar-ly01011-shows-equivalence-to-reference-product-for-bone-metastases

5. Jeremias S. Ten years of data support the safety of biosimilar filgrastim for donor mobilization. The Center for Biosimilars. August 22, 2025. Accessed September 2, 2025. 

https://www.centerforbiosimilars.com/view/ten-years-of-data-support-safety-of-biosimilar-filgrastim-for-donor-mobilization

6. Jeremias S. Canadian RWE shows comparable outcomes between etanercept biosimilars, originator. The Center for Biosimilars. August 26, 2025. Accessed September 2, 2025. 

https://www.centerforbiosimilars.com/view/canadian-rwe-show-comparable-outcomes-between-etanercept-biosimilars-originator

7. Jeremias S. Low prices fail to boost insulin biosimilar uptake in the UK. The Center for Biosimilars. August 11, 2025. Accessed September 2, 2025. 

https://www.centerforbiosimilars.com/view/low-prices-fail-to-boost-insulin-biosimilar-uptake-in-the-uk

Articles

August 2025 brought significant advancements in biosimilars, including financial successes, new product launches, and research on ongoing challenges in market access.

Biosimilars News Roundup: August 2025

The competitive landscape for bone health treatments in the US has intensified with the 

 of Bildyos (denosumab-nxxp) and Bilprevda (denosumab-nxxp), biosimilars to Amgen’s reference products Prolia and Xgeva, respectively.

The FDA has approved 2 biosimilars, denosumab-nxxp (Bildyos) and (Bilprevda), referencing denosumab (Prolia) and denosumab (Xgeva), respectively, for use in all indications of the reference products. | Image Credit: gguy - stock.adobe.com

The approval, granted to Shanghai Henlius Biotech and Organon, marks the fifth pair of denosumab biosimilars to receive FDA clearance, promising to further expand access to more affordable treatment options for millions of patients facing osteoporosis and cancer-related bone complications. 

Denosumab is a crucial therapeutic agent, functioning as a human monoclonal antibody that binds to the RANKL protein, thereby preventing the activation of the RANK receptor on osteoclasts and inhibiting osteoclastic bone resorption. The reference products, Prolia and Xgeva, are widely used for various bone-related conditions, including osteoporosis, bone metastases, hypercalcemia of malignancy, and giant cell tumor of bone. The introduction of multiple biosimilars is expected to drive down costs and improve patient access.

The journey of denosumab biosimilars to the US market began relatively recently, with a flurry of approvals over the past year and a half:

Sandoz's Wyost and Jubbonti (denosumab-bddz for both) received FDA approval in March 2024, becoming the first biosimilars to reference Xgeva and Prolia, respectively, in the US.

Both Wyost and Jubbonti were also granted interchangeability designations with their reference products, allowing for pharmacy-level substitution without requiring prior physician approval. At the time of their approval, there were no denosumab biosimilars approved in the European Union. These biosimilars were the first denosumab biosimilars to launch in the US in June 2025.

In February 2025, Samsung Bioepis' Ospomyv and Xbryk (denosumab-dssb for both; SB16) gained approval from both the FDA and the European Medicines Agency (EMA).

 This pair also received an interchangeability designation and is currently "waiting in the wings to launch" in the US. Ospomyv references Prolia, and Xbryk references Xgeva.

Following this, the FDA approved Celltrion's Stoboclo and Osenvelt (denosumab-bmwo for both) on March 4, 2025. Stoboclo references Prolia, and Osenvelt references Xgeva. These biosimilars launched in the US in July 2025.

Fresenius Kabi's Conexxence and Bomyntra (denosumab-bnht for both) also received FDA approval in March 2025.

 Conexxence references Prolia, and Bomyntra references Xgeva. These biosimilars were approved for all indications of their respective reference products. Fresenius Kabi announced the commercial availability of these products in the US on July 1, 2025, and also plans to launch in Europe in the second half of 2025, pending regulatory approvals.

Henlius and Organon's Comprehensive Approval

The newest additions, Bildyos (denosumab-nxxp) and BILPREVDA (denosumab-nxxp), have been approved for all indications of their respective reference products.

 This broad approval was based on a comprehensive data package, including structural and functional analytical data, clinical pharmacokinetic data, and a comparative clinical study demonstrating that Bildyos and Bilprevda are highly similar to and have no clinically meaningful differences from their reference products, Prolia and Xgeva, respectively, in terms of safety, purity, and potency.

Bildyos, referencing Prolia, is indicated for:

Treatment of postmenopausal women with osteoporosis at high risk for fracture.

To increase bone mass in men with osteoporosis at high risk for fracture.

Treatment of glucocorticoid-induced osteoporosis in men and women at high risk for fracture.

To increase bone mass in men at high risk for fracture receiving androgen deprivation therapy for nonmetastatic prostate cancer.

To increase bone mass in women at high risk for fracture receiving adjuvant aromatase inhibitor therapy for breast cancer. 

Bildyos is supplied as a 60 mg/mL injection. A boxed warning regarding severe hypocalcemia in patients with advanced chronic kidney disease (CKD), including those on dialysis, accompanies Bildyos, and treatment in these individuals should be supervised by a health care provider with expertise in CKD-MBD.

Bilprevda, referencing Xgeva, is approved for:

The prevention of skeletal-related events in patients with multiple myeloma and bone metastases from solid tumors. 

The treatment of giant cell tumor of bone in adults and skeletally mature adolescents where surgical resection is unresectable or likely to result in severe morbidity.

The treatment of hypercalcemia of malignancy refractory to bisphosphonate therapy. Bilprevda is available as a 120 mg/1.7 mL injection. 

Safety concerns for Bilprevda include hypersensitivity reactions, severe symptomatic hypocalcemia, osteonecrosis of the jaw, atypical subtrochanteric and diaphyseal femoral fractures, multiple vertebral fractures following treatment discontinuation, and embryo-fetal toxicity, necessitating effective contraception for females of reproductive potential. 

Although the sources highlighted interchangeability status for Sandoz's and Samsung Bioepis' products, there was no mention of an interchangeability designation for Henlius and Organon's Bildyos and Bilprevda in the provided information.

Jon Martin, US commercial lead for biosimilars and general medicines at Organon, emphasized the significance of these approvals, stating, "Our goal with these biosimilars is to improve access and affordability across multiple therapeutic areas, including for osteoporosis, which disproportionately affects women." 

Jason Zhu, PhD, executive director and CEO of Henlius, added that the approvals underscore their commitment to "expanding access to quality biologics... delivering biosimilar treatment options that are as safe and effective as the reference biologics to more patients across the US." 

1. Shanghai Henlius Biotech, Inc. US Food and Drug Administration (FDA) approves Henlius and Organon’s Bildyos (denosumab-nxxp) and Bilprevda (denosumab-nxxp), biosimilars to Prolia (denosumab) and Xgeva (denosumab), respectively-media. September 2, 2025. Accessed September 2, 2025. 

https://www.henlius.com/en/NewsDetails-5427-26.html

2. Jeremias S. FDA approves first denosumab biosimilars. The Center for Biosimilars

. March 5, 2024. Accessed September 2, 2025. 

https://www.centerforbiosimilars.com/view/fda-approves-first-denosumab-biosimilar

3. Jeremias S. Wyost and Jubbonti launch as first denosumab biosimilars in the US. The Center for Biosimilars. June 2, 2025. Accessed September 2, 2025. 

https://www.centerforbiosimilars.com/view/wyost-and-jubbonti-launch-as-first-denosumab-biosimilars-in-the-us

4. Jeremias S. Two more pairs of denosumab biosimilars enter US market. The Center for Biosimilars. July 9, 2025. Accessed September 2, 2025. 

https://www.centerforbiosimilars.com/view/two-more-pairs-of-denosumab-biosimilars-enter-us-market

5. Santoro C. FDA approves another pair of denosumab biosimilars, Conexxence and Bomyntra. The Center for Biosimilars. March 27, 2025. Accessed September 2, 2025. 

https://www.centerforbiosimilars.com/view/fda-approves-another-pair-of-denosumab-biosimilars-conexxence-and-bomyntra

New denosumab biosimilars, Bildyos and Bilprevda, enhance access to affordable osteoporosis and bone disease treatments, promising significant patient benefits.

FDA Greenlights Fifth Pair of Denosumab Biosimilars: Bildyos and Bilprevda

Here are the top 5 biosimilar articles for the week of August 25, 2025.

, the first interchangeable insulin aspart biosimilar, enhancing access to affordable diabetes care for millions.

, audiences can discover the latest advancements in the biosimilar landscape, including the first patent lawsuit regarding a petuzumab biosimilar, a new ustekinumab biosimilar launch, and a new strategy for unbranded biosimilar access.

Number 3: New research confirms the romiplostim biosimilar GP40141 offers 

 for treating immune thrombocytopenia, enhancing treatment accessibility.

 of 244 healthy stem cell donors found no new safety concerns with Sandoz’s filgrastim biosimilar, reinforcing its long-term safety for donor mobilization.

 in remission outcomes between etanercept biosimilars and the originator, Enbrel, for rheumatoid arthritis patients.

Videos

The Top 5 Biosimilar Articles for the Week of August 25

Alvotech, an Iceland-based biosimilar-focused biotech company, marked a significant financial milestone in the first half of 2025, swinging from a substantial loss to a net profit, driven by the strong commercial performance of its key biosimilar products.

 The company's financial results pointed to a more than 200% year-on-year increase in product revenues, which fueled its first-ever quarterly positive cash flow from operations.

Alvotech achieves a remarkable financial turnaround in 2025, reporting a net profit driven by strong biosimilar sales and strategic partnerships. | Image credit: vadish - stock.adobe.com

For the first 6 months of the year, Alvotech reported a net profit of $141.7 million, a stark reversal from the $153.5 million net loss it experienced during the same period in 2024. Total revenue for the period was $306 million, a 30% increase from the $236 million reported in the first half of 2024. This growth was largely attributed to a massive jump in product revenue, which surged to $204.7 million from just $65.9 million a year prior.

Alvotech Chairman and Chief Executive Officer Robert Wessman noted the momentum, stating that the results "confirm our business momentum and the opportunities that lie ahead." He added that new and expanded partnerships reflected the company's increased development activity. The company's cash and cash equivalents stood at $151.5 million as of June 30, 2025, bolstered by the robust operational performance.

The company's financial success was fueled primarily by the market expansion of its 2 approved biosimilars, a high-concentration adalimumab (Humira) biosimilar and an ustekinumab (Stelara) biosimilar. The adalimumab biosimilar, marketed as Simlandi in the US and Hukyndra in Europe, continued its strong sales trajectory. Simlandi received FDA approval as the first high-concentration, citrate-free interchangeable biosimilar to Humira in February 2024, a key advantage in the competitive US market.

The ustekinumab biosimilar, known as Selarsdi in the US and Uzpruvo in Europe, also contributed significantly to the revenue surge.

 After gaining interchangeable status from the FDA in April 2025, the product's market share in the US reached more than 20% of the overall Stelara market in July 2025, meeting the company's internal projections.

Beyond its launched products, Alvotech maintains a pipeline of biosimilar candidates for various therapeutic areas, including autoimmune disorders, eye disorders, and oncology. Several programs progressed this year, with some transitioning out of the clinical phase. The company's biologics license applications (BLA) for proposed biosimilars to Prolia/Xgeva (denosumab) and Eylea (aflibercept) were accepted by the FDA. The aflibercept biosimilar, now named Mynzepli, recently secured European approval, marking a critical step toward commercialization.

Alvotech also broadened its strategic partnerships, licensing European rights to 3 new biosimilar—referencing Ilaris (canakinumab), Kesimpta (ofatumumab), and an undisclosed biologic—from Advanz Pharma.

 A collaboration agreement was also established with Dr. Reddy's for AVT32, a biosimilar candidate to Keytruda (pembrolizumab).

To further bolster its research and development capabilities, Alvotech acquired Xbrane Biopharma’s research and development operations in Sweden in March 2025 for SEK 275 million (approximately $28.9 million).

 The acquisition also included a biosimilar candidate to Cimzia (certolizumab pegol), now designated as AVT10. The company’s strategic moves and financial performance underscore its ambition to become a global leader in the biosimilar space.

1. Alvotech reports results for the first six months of 2025 and provides a business update. News release. Alvotech. August 13, 2025. Accessed August 26, 2025. 

https://investors.alvotech.com/news-releases/news-release-details/alvotech-reports-results-first-six-months-2025-and-provides

2. Jeremias S. Eye on pharma: Simlandi US launch; ranibizumab partnership; expanded access for adalimumab biosimilars. The Center for Biosimilars

. May 27, 2024. Accessed August 26, 2025. 

https://www.centerforbiosimilars.com/view/eye-on-pharma-simlandi-us-launch-ranibizumab-partnership-expanded-access-for-adalimumab-biosimilars

3. Jeremias S. 3 Ustekinumab biosimilars launch on US market. The Center for Biosimilars. February 24, 2025. Accessed August 26, 2025. 

https://www.centerforbiosimilars.com/view/3-ustekinumab-biosimilars-launch-on-us-market

4. Jeremias S. Eye on pharma: interchangeability labels and expanded biosimilar partnerships. The Center for Biosimilars. May 29, 2025. Accessed August 26, 2025. 

https://www.centerforbiosimilars.com/view/eye-on-pharma-interchangeability-labels-and-expanded-biosimilar-partnerships

5. Jeremias S. Eye on pharma: Keytruda biosimilar deal; German court bans Imraldi; new biosimilars for Japan. The Center for Biosimilars. June 17, 2025. Accessed August 26, 2025. 

https://www.centerforbiosimilars.com/view/eye-on-pharma-keytruda-biosimilar-deal-german-court-bans-imraldi-new-biosimilars-for-japan

Alvotech achieves a remarkable financial turnaround in 2025, reporting a net profit driven by strong biosimilar sales and strategic partnerships.

Alvotech Reports Record-Breaking First Half of 2025 Amid Strong Biosimilar Sales

As the US continues to wait for etanercept biosimilars to be allowed entrance into the market,

 a new Canadian analysis using real-world evidence (RWE) found no meaningful differences in remission outcomes between individuals with rheumatoid arthritis (RA) initiating etanercept biosimilars and those starting the reference product.

As the US continues to wait for etanercept biosimilars to be allowed entrance into the market, a new Canadian analysis using real-world evidence (RWE) found no meaningful differences in remission outcomes between patients treated with etanercept biosimilars vs the reference product. | Image credit: ungvar - adobe.stock.com

, evaluated 150 adults with RA from 4 Canadian prospective cohorts who initiated etanercept therapy between January 2015 and May 2022. Participants were etanercept naive at baseline, and 65.3% (n = 98) received a biosimilar (Brenzys or Erelzi), while 34.7% (n = 52) received the originator (Enbrel).

The overall cohort was predominantly female (76.0%) and largely White (82.2%). The mean age at etanercept initiation was 56.8 years, with individuals in the biosimilar group diagnosed at a younger age than those in the originator group (mean, 47.7 vs 54.2 years). The mean RA duration was longer among biosimilar initiators (9.3 years vs 5.1 years). Obesity (body mass index ≥ 30) was reported in 41.4% of participants, and 16.0% were current smokers. Most individuals (72.7%) initiated therapy after 2017, reflecting the 2016 approval of the first etanercept biosimilar in Canada.

Among the 125 participants with active disease at baseline, the median time to first remission was 8.7 months (95% CI, 5.2-12.1) for biosimilar users and 14.5 months (95% CI, 4.7-18.6) for originator users. However, the difference was not statistically significant (log-rank 

 = .51). Multivariate Cox regression showed no clear difference in time to first remission (adjusted HR, 1.52; 95% CI, 0.68-3.39).

Sustained remission, defined as at least 2 consecutive visits in remission within 12 months, was achieved by 19.5% of biosimilar initiators and 21.0% of originator initiators. Adjusted analyses showed no significant difference (adjusted OR, 1.14; 95% CI, 0.29-4.87). The only baseline factor associated with increased likelihood of remission was hydroxychloroquine use (adjusted HR, 1.96; 95% CI, 1.01-4.73).

The findings mirror results from randomized controlled trials and European registry data, which have consistently shown comparable outcomes between etanercept biosimilars and the originator. Observational studies in the UK and Catalonia also reported similar remission rates, reinforcing the clinical interchangeability of biosimilars.

Biosimilars are increasingly important to managed care systems due to their potential to expand access and reduce costs, with some estimates predicting that biosimilars could generate $180 billion by 2028.

 In Canada, biologics accounted for 27.3% of public drug expenditures in 2018 despite representing less than 2% of claims.

 Policy makers have responded by implementing biosimilar adoption initiatives, contributing to greater RWE for these products.

By contrast, in the US, etanercept biosimilars have faced delayed market entry.

 Although the FDA approved Erelzi (Sandoz) in 2016 and Eticovo (Samsung Bioepis) in 2019, patent litigation with Amgen has kept them off the US market. Enbrel, first approved in 1998, continues to face limited biosimilar competition, highlighting a key barrier to affordability in the US health care system.

The authors of the present analysis concluded, “Biosimilars present an opportunity to expand treatment options for RA patients while mitigating healthcare costs. Our study contributes to the growing body of evidence supporting the equivalence of biosimilars and bio-originators.”


1. Herman B. Amgen wins Enbrel drug patent appeal. Axios. July 2, 2020. Accessed August 25, 2025. 

https://www.axios.com/2020/07/02/amgen-enbrel-drug-patent-appeal

2. Birck MG, Boivin J, Yan L, et al. Disease remission and sustained remission after etanercept biosimilar or originator initiation in rheumatoid arthritis: an interim real-world analysis. 

 2025;27:150. doi:10.1186/s13075-025-03607-7

3. Joszt L. Biosimilars can create huge savings, but interchangeability needs to be reviewed. 

. April 10, 2023. Accessed December 17, 2024. 

www.ajmc.com/view/biosimilars-can-create-huge-savings-but-interchangeability-needs-to-be-reviewed

4. Lexchin J, Law MR. Policies on the use of biosimilars in Canada: developments over the past 5 years. 

. 2022;194(15):E556-E560. doi:10.1503/cmaj.211599

5. Jeremias S. Given public concerns, Canadian policy makers should be cautious when making new biosimilar policies. The Center for Biosimilars

. May 5, 2022. Accessed August 25, 2025. 

https://www.centerforbiosimilars.com/view/given-public-concerns-canadian-policy-makers-should-be-cautious-when-making-new-biosimilar-policies

Canadian study reveals no significant differences in remission outcomes between etanercept biosimilars and the originator, Enbrel, for rheumatoid arthritis patients.

Canadian RWE Shows Comparable Outcomes Between Etanercept Biosimilars, Originator

Here are the top 5 biosimilar articles for the week of August 18, 2025.

The Top 5 Biosimilar Articles for the Week of August 18

A 10-year prospective follow-up of 244 healthy stem cell donors found no new safety concerns with Sandoz’s filgrastim biosimilar, reinforcing its long-term safety for donor mobilization. | Image credit: sola_sola - stock.adobe.com

A 10-year prospective surveillance study of healthy stem cell donors who received the Sandoz biosimilar filgrastim (Zarzio, marketed as Filgrastim Hexal in Germany) for hematopoietic stem and progenitor cell (HSPC) mobilization reported no evidence of long-term safety concerns, providing reassurance for the continued use of granulocyte colony-stimulating factors (G-CSFs) in donor mobilization.

) study enrolled 244 adult, healthy, unrelated stem cell donors from the Deutsche Stammzellspenderdatei registry at 2 German centers. Participants received at least 1 dose of Sandoz’s filgrastim biosimilar, Zarzio, administered subcutaneously for up to 5 days to mobilize stem cells for collection by leukapheresis. Median donor age was 34 years (mean [SD], 35.8 [9.8] years; range, 19-60 years), and approximately three-fourths of participants were male. Median body mass index was 26.9 kg/m², placing the cohort in the overweight category.

Follow-up included structured assessments of physical and mental health, self-reported outcomes via the SF-12 questionnaire, and adverse event (AE) reporting at baseline, 1, 6, and 12 months after apheresis, and annually for 10 years.

Nearly all donors (95%) reported at least 1 AE during the initial mobilization period, with bone pain being the most common. After this period, a total of 564 AEs were documented, with median onset occurring about 4 years after mobilization (3.86 years for women and 4.02 years for men).

The majority of AEs were musculoskeletal or connective tissue disorders (n = 134) and infections or infestations (n = 130). Other categories included gastrointestinal (n = 29), endocrine (n = 18), and vascular disorders (n = 16). A total of 98 serious AEs were reported in 56 donors, but none were deemed related to biosimilar filgrastim.

Age and sex differences emerged: younger donors had significantly lower AE rates compared with older donors (rate ratio, 0.64; 95% CI, 0.43–0.95; 

 = .026). Female donors experienced higher annual AE rates than male donors (0.40 vs 0.21 AEs/year; rate ratio, 1.87; 95% CI, 1.32–2.64; 

Twelve women reported 13 pregnancies following donation, resulting in 14 live births. Pregnancy-related AEs—such as gestational diabetes, cervical incompetence, and gestational hypertension—occurred only once each, with no clustering or suspected relationship to prior biosimilar filgrastim exposure. No miscarriages, congenital anomalies, or neonatal complications were reported.

SF-12 assessments indicated that donors maintained superior average physical health scores compared with the general German population, even after 10 years (53.0 [6.9] vs 43.1 [6.9]; 

 < .0001). Mental health scores remained comparable to population averages. Neither long-term declines in health nor increased incidence of malignancies were observed. Importantly, the COVID-19 pandemic did not appear to affect donor well-being during follow-up.

Sandoz, the developer of Zarzio, funded the study. Authors concluded that the findings confirm the established safety profile of filgrastim biosimilars and provide critical long-term reassurance for donor safety in the context of allogeneic transplantation.

“No new or excessive adverse events were identified during a 10-year follow-up of mobilized stem cell donors and therefore reassure about the overall safety of stem cell mobilization with G-CSF in healthy volunteers,” wrote the investigators.

The results bolster confidence in biosimilar filgrastim products as safe, cost-effective alternatives to reference filgrastim for HSPC mobilization, supporting their continued integration into transplantation practice and managed care formularies.

A Brief History of Zarzio/Zarxio in the EU and US

Sandoz’s filgrastim biosimilar was first approved in Europe in 2009 under the brand name Zarzio.

 Approval was based on phase 3 confirmatory clinical data—the most sensitive population being patients with breast cancer undergoing myelosuppressive chemotherapy—and regulatory extrapolation of other indications such as stem cell mobilization and chronic neutropenia. Over the subsequent decade, real-world evidence, including the MONITOR-GCSF study (

) across 12 European countries (n = 1447), supported Zarzio’s efficacy and safety in oncology treatments.

In the US, Sandoz’s biosimilar (filgrastim-sndz, branded as Zarxio) became the first FDA-approved biosimilar on March 6, 2015, under the Biologics Price Competition and Innovation Act pathway.

 Its approval was grounded in a robust "totality of evidence," which included structural/functional characterization, nonclinical and clinical comparability, and the PIONEER trial data (

A 10-year prospective follow-up of 244 healthy stem cell donors found no new safety concerns with Sandoz’s filgrastim biosimilar, reinforcing its long-term safety for donor mobilization.

Skylar Jeremias

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