Health Law Daily Wrap Up, ANTITRUST—E.D. Pa.: Generic drug makers largely fail to exclude Humana damages expert opinion, (Aug 17, 2026)

By Steven Melendez

The court allowed the report to stand, except for portions referring to states not addressed in litigation and arguments around causation.

A federal judge found the vast majority of Humana Inc.’s damages expert opinions admissible under Fed. R. Civ. P. 702 and Daubert v. Merrell Dow Pharmaceuticals, Inc. for an upcoming trial in the first bellwether case involving a direct-action plaintiff in ongoing multidistrict litigation (MDL) about alleged generic drug price-fixing. The court excluded portions referring to a causal relationship between alleged price-fixing and price increases, finding insufficient support, and damages estimates related to Ohio and Indiana, where Humana has no relevant claim (In Re: Generic Pharmaceuticals Pricing Antitrust Litigation, No. 2:18-cv-03299-CMR (E.D. Pa. Aug. 11, 2026)).

Background. The Humana bellwether is one of several direct-action cases in a broader generic drug pricing MDL. The MDL also includes complaints by other purchasers and payors alleging price-fixing claims against various generic drug maker defendants. Humana alleged that the drug makers increased prices on certain generic drugs in violation of antitrust laws and conspired to allocate market share, and that those price increases caused Humana financial harm. Humana’s claims involve both claims as an indirect purchaser, based on insurance payments made on behalf of members who submitted claims under their prescription drug coverage; and claims as a direct purchaser based on the transactions of its Humana Pharmacy, Inc. subsidiary. The pharmacy subsidiary purportedly bought generic drugs directly from the drug makers for distribution to plan members on a mail-order and retail pharmacy basis.

In June, the court held hearings on various motions including motions to exclude various experts, including Humana’s damages expert, Dr. William B. Vogt, a former university professor who is now research director at a healthcare consulting firm. The drug makers argued that the court should exclude Vogt’s testimony, arguing a difference-in-differences (DID) regression model he used is flawed and unreliable, that he incorrectly assumed a 100 percent pass-through of overcharges to Humana, and that he failed to net out Medicare Part D subsidies and amounts related to unpled claims.

DID model. Vogt calculated an “estimated overcharge” on the relevant drugs and applied that to what Humana spent on the drugs during the alleged collusion period. He began by choosing other drugs that shared characteristics with the relevant drugs but weren’t subject to price-fixing allegations as controls, assessing how the price differences evolved during the alleged collusion period.

The drug makers challenged his selection of control drugs, his use of molecule-level pricing data from IQVIA, and his “reliance on purportedly arbitrary start dates and end dates,” and argued he failed to supplement the model with causal analysis of price increases.

The court found that the IQVIA data is widely used by courts for measuring damages to third-party payors. With regard to start and end dates, the dates are derived from another expert’s report that Humana previously sought unsuccessfully to exclude and thus not subject to exclusion. That expert, Dr. W. David Bradford, derived the start dates from a “permissible document review” and end dates based on the defendants’ requested stipulation, according to the ruling. The court found, though, that Bradford did not address causality and thus excluded elements of Vogt’s report that assume causality.

The drug makers also argued that Vogt’s control drug selection did not meet a “parallel pre-trends” condition, meaning that control and test groups evolved similarly in a period before the alleged collusion. The drug makers argued Vogt tested that condition visually, rather than with statistical techniques they argue represent standard practice. The court found that that “rigorous testing would be helpful here,” but other courts have either found such a test supported by scientific literature or even declined to exclude an expert who made no pre-trends analysis, finding that also supported in the literature. Vogt also tested his model and controls with sensitivity checks, the court noted, finding the drug makers’ critiques better suited for cross-examination.

Pass-through costs. The drug makers also argued Vogt’s analysis was unreliable because he assumed all overcharge at the manufacturer level would be passed through to Humana. Vogt had claimed that wholesalers operate at low margins, making them poorly equipped to absorb rather than pass on price increases. Similarly, he argued, pharmacies are incentivized to pass on price increases based on relationships with insurers and pharmacy benefit managers (PBMs). He also increases in Humana’s indirect-purchase data with manufacturer-level IQVIA data for all subject drugs and found that a 100 percent pass-through rate was, if anything, a low estimate.

The court found that any imprecisions in Vogt’s findings are not severe enough to require exclusion.

Medicare Part D. The drug companies also argued that Vogt failed to take into account federal Medicare Part D subsidies paid to Humana. The federal government effectively pays for a significant amount of the cost of prescription drugs not addressed in the report, they argued. But the court found that this argument is premature, with courts previously not excluding an expert who failed to take this into account. This may affect the strength of Vogt’s analysis but does not “does not undermine the validity of his model or that model’s capacity to provide a baseline from which to apply an offset,” according to the ruling.

Unpled claims. Humana has pleaded state antitrust and consumer protection claims under the laws of 36 jurisdictions and unjust enrichment claims under the laws of the District and Columbia and all U.S. territories and state except Ohio and Indiana. Vogt computed indirect damages for purchases in all 50 states, D.C., and Puerto Rico. The court excluded state projections for Ohio and Indiana, which it found not connected to any claim pled by Humana.

The Case is No. 2:18-cv-03299-CMR.

Judge: Rufe, C.

Attorneys: James Caleigh MacDonald (Schneider Wallace Cottrell Kim LLP) for Humana Inc. Sheron Korpus (Kasowitz LLP) for Actavis Elizabeth, LLC.

Companies: Humana Inc.; Actavis Elizabeth, LLC

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