The $700,000 Question: Why Humira Biosimilars Still Need a Push

One of my manufacturing clients with 1,200 employees spent $1.9 million on specialty drugs in 2025. Nearly $700,000 of that tied back to Humira. They’d heard about biosimilars launching and assumed the savings would just show up. A year later, their pharmacy spend barely budged. The PBM kept routing claims to the original Humira since AbbVie’s rebates made it the “preferred” version. That story repeats across mid-market employers who expected biosimilars to fix themselves once the products existed.

In 2026, more than ten adalimumab biosimilars are available in the U.S., most priced 40-70% below Humira after discounts. Yet many employers still aren’t seeing that difference in their actual claims data. The reason isn’t supply, it’s contracting. PBMs that hinge value on rebate revenue keep list prices high upstream, so even if rebate checks look fine, the employer’s net cost stays inflated. By contrast, those using transparent or pass-through PBMs, Navitus, Capital Rx, RxBenefits-administered setups, are watching their cost-per-claim drop right away because the formulary locks on lowest net cost instead of biggest rebate.

The unlock comes through active formulary management. Don’t trust a PBM’s “preferred” biosimilar list without scrutiny. Employers should push for claim-level biosimilar conversion guarantees and strip rebate bias out of the model entirely. For a deeper view into net-cost versus rebate models, try RxPBM.ai. You’ll see how big the gap really is.

When Stelara Biosimilars Hit, Everything Shifted

The back half of 2025 shook up inflammatory and GI drug spending as Stelara biosimilars entered the mix. At roughly $120,000 per therapy year, even one or two claimants distort totals fast. In an RFP I ran for a 900-life financial firm, Humira, Stelara, and Dupixent made up 46% of the total pharmacy cost. Once their PBM split rebates between the reference drug and biosimilar versions, their net spend dropped 9%. That’s about $210,000 in one year, mostly from Stelara conversions rolling through by early 2026.

Results like that don’t happen by accident. They require tight coordination: PBM, stop-loss carrier, and prescribers on the same page. Many doctors stick with the brand they know, habit and prior-authorization hurdles slow change. The employers who make biosimilar conversion work share a few traits: early member communication, simple clinical criteria, and matching rules between medical and pharmacy benefits. If biosimilar-first logic applies everywhere, leakage to the medical benefit all but disappears.

One more thing: check your prior-authorization templates. Some still list only the brand, which quietly blocks biosimilar access. A quick quarterly review with the PBM’s clinical team fixes that before it drains your spend for another year.

Then There’s Eylea: The Cost No One Saw Coming

Ophthalmic biologics used to fly under the radar, but no longer. Eylea (aflibercept) now sits near the top of many self-funded specialty spend reports, especially for plans with older demographics. With injections averaging $2,000 and happening monthly or bi-monthly, totals climb fast. A 500-employee client of mine ended up spending $180,000 on just three members last year.

Biosimilar versions of Eylea arrived in early 2026 with roughly 35-45% lower net cost. The catch: Eylea straddles pharmacy and medical benefits, so savings depend on who’s actually billing. If those data streams aren’t integrated, employers miss the price cut entirely. I’ve seen PBMs plug biosimilar-first rules under the pharmacy benefit while the same product sails along under the medical benefit at full reference price. Frustrating, and fixable.

The solution is syncing benefits before renewal season. Some employers shift Eylea into the pharmacy benefit for tighter auditing, others rely on the medical carrier to apply biosimilar parity clauses. Either path works if both sides talk. Check RxInfo.ai for product-level comparisons that make this discussion a little easier to navigate.

Rebate Compression and the PBM Profit Dilemma

PBMs built their economics on rebates. Biosimilars are blowing that up. As more discounted biosimilars flood in, the rebate pool evaporates. Some PBMs double down on still-rebated reference brands to preserve margin, which ironically raises employer costs. Transparent PBMs, meanwhile, lean into lowest net cost per claim and skip the rebate game altogether. That split widened in 2026 as biosimilar use spread.

Employers often ask me whether giving up rebates makes sense. Run the math: it usually does. One 2,000-life manufacturer I worked with spent $3.6 million a year. Their PBM kept Humira as preferred thanks to a 40% rebate, producing a $4,200 net cost per claim. A biosimilar switch under a transparent model dropped the gross cost to $2,400, no rebate needed. Even without the $280,000 rebate check, the employer banked over $500,000 more in savings. That’s not rebate sacrifice, that’s common sense.

Regulatory risk is climbing too. ERISA fiduciary standards are creeping into pharmacy oversight, and opaque rebate models are harder to defend. Employers tying PBM payments to measurable performance, per-claim admin fees, outcomes guarantees, are on safer and smarter ground. The rest, honestly, are waiting for a letter from their counsel.

So What Should Employers Actually Do in 2026?

Biosimilars aren’t theoretical anymore; they’re a concrete lever for cost control. But the lever doesn’t pull itself. Employers can start small and still see meaningful savings if they tighten the right bolts:

• Ask for a biosimilar adoption report. Get claim-level detail showing which biosimilars exist and which ones your members are actually using.
• Rebuild your formulary logic. Strip out rebate-weighted tiers that keep brands artificially on top.
• Unify medical and pharmacy oversight. For crossover drugs like Eylea or Remicade, aligned rules reveal hidden spend.
• Talk to your members. People expect “brand” drugs to mean higher quality. Communication about FDA biosimilar standards reduces confusion and complaints.

Even half measures help. A 900-life professional services client adopted a biosimilar-first plan in 2025 and cut $280,000 from a $2.1 million pharmacy budget without touching access. With Tysabri and Soliris biosimilars on deck later this year, the window’s wide open. Look, the rebate era is fading faster than most employers realize. The real game now? Paying the lowest defensible net cost for the same clinical result. And then moving on to the next fire.