Specialty drug spending rose 12.5% in 2025, driven by higher utilization and rebate adjustments, according to a new report from the Pharmaceutical Strategies Group (PSG). Gross costs per member per year climbed to $1,548, while net costs settled at $1,251. The analysis also projects a 32% surge in gross per‑member‑per‑year (PMPY) specialty costs by 2028.
Utilization pushes more members onto high‑cost therapies
PSG’s VP of research and marketing, Morgan Lee, said the rise reflects “more members taking specialty drugs” and an increasing percentage of members on such therapies each year. The share of members using at least one specialty drug grew from 4.4% in 2023 to 5.5% in 2025, suggesting broader patient exposure to these treatments.
Biosimilar uptake has moderated per‑claim costs, but new drug approvals and expanded indications have lifted overall utilization. Overall biosimilar market share rose from 22.6% in 2023 to 56.3% in 2025. Notably, Humira (adalimumab) biosimilars surged from 0.3% to 82.4% market share, while Stelara (ustekinumab) biosimilars captured 18% in their first year.
Lee noted that “Humira went from being the number one drug by spend in our 2024 report, and by 2025, it had dropped out of the top 10.” He attributed the shift to pharmacy‑benefit managers (PBMs) implementing aggressive biosimilar strategies, reshaping the top‑spending drug list.
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Inflammatory medications still dominate specialty spending. Eight of the top ten drugs are anti‑inflammatory agents, a fact that “payers looking at utilization management and coverage decisions… it’s a big one,” according to the analyst.
Top spenders and the impact of biosimilars
The 2025 PSG report lists Skyrizi (risankizumab‑rzaa) from AbbVie and Dupixent (dupilumab) from Sanofi/Regeneron as the highest‑spending specialty drugs. Skyrizi treats psoriasis, Crohn’s disease, and ulcerative colitis, while Dupixent is approved for atopic dermatitis, asthma, COPD, and other inflammatory conditions. Expanded indications, direct‑to‑consumer advertising, and shifting utilization after Humira and Stelara biosimilars entered the market likely contributed to their spending growth.
Stelara, approved for psoriasis, Crohn’s disease, and ulcerative colitis, remains among the highest spenders. Its biosimilars launched last year.
Rebates continue to influence pricing for both branded products and biosimilars. Josh Van Ginkel, PSG’s VP of plan sponsor consulting, explained that “manufacturers started offering deeper discounts on the back end” as biosimilars gained traction, but some of the anticipated savings were offset by patients moving to more expensive brand drugs.
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PSG anticipates continued growth in specialty drug spend, driven by new, higher‑priced drugs entering the pipeline and expanding indications that draw more patients into treatment, Lee said.
Regulatory pressure from the White House, Congress, and state insurance departments could eventually curb specialty prices. Some employers are already removing high‑cost specialty drugs from coverage, forcing patients to either pay out‑of‑pocket or switch to a covered alternative, Van Ginkel noted.
Non‑specialty drugs gain attention amid GLP‑1 growth
PSG added a new section on non‑specialty drugs in its 2025 report, citing the growing use of GLP‑1 agonists for diabetes and obesity. Historically, non‑specialty spend grew slowly, but “there’s this combination of expensive drugs, as well as more people taking those drugs,” the researcher said.
Diabetes accounts for about a third of non‑specialty spend, yet the rise in GLP‑1 use for weight loss is a major driver of overall cost increases. While obesity drugs represent roughly 4% of non‑specialty pharmacy spend on average, that share can exceed 20% for employers with broad GLP‑1 coverage for weight loss.
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Van Ginkel reported that roughly one‑third of large employers (those with over 10,000 covered lives) now cover GLP‑1s for weight loss, aligning with PSG’s survey data. Employers are pursuing two strategies: some fund counseling and lifestyle programs to sustain weight‑loss results, while others rely on prior authorization, body‑mass‑index (BMI) requirements, and limited prescriber networks to control spending.
Employers watch costs closely.
PSG’s data shows heavy use of BMI and prior‑authorization requirements but low uptake of prescriber‑network restrictions. Both Lee and Van Ginkel expect GLP‑1 prices to fall as more products enter the market, likely prompting broader coverage. “I tend to see more coverage of GLP‑1s for weight loss in highly competitive hiring markets,” Van Ginkel said, noting that employers in tight labor markets use these benefits to attract and retain talent.
Overall, the report notes that specialty drug spending remains on an upward path, with utilization and new indications outpacing the cost‑containment effects of biosimilars and rebates. Employers and payers will need to balance coverage decisions, benefit design, and regulatory influences as the pharmaceutical environment keeps changing.
