(Aaron Couture)

Pfizer has asked the federal judge handling the multidistrict litigation alleging that its antidepressant drug Zoloft causes birth defects to limit a key plaintiffs expert’s testimony to the content of her report.

The plaintiffs responded that Pfizer had kept their expert, Dr. Anick Berard, from explaining her methods during deposition. The drug company now characterizes Berard’s method for citing to scientific studies as flawed, arguing that she “cherry-picked” studies and disregarded ones that didn’t support her proposition that Zoloft can cause birth defects in babies born to women who took the drug while pregnant.

“If Pfizer does not know why Dr. Berard relied on certain studies and rejected others, after having deposed her, it is because it did not want to know,” the plaintiffs argued in a bench memorandum.

“Any attempt by plaintiffs’ experts to now cure their reports with opinions or analyses not disclosed in their reports would be improper and the court should ‘restrict the expert’s testimony’ to the discussion in the reports,” Pfizer said in its bench brief.

U.S. District Judge Cynthia Rufe of the Eastern District of Pennsylvania is handling the case and held Daubert hearings last week, for which she invited Philadelphia Court of Common Pleas Judge Lisa Rau to sit. Rau is handling all of the Zoloft cases on the Philadelphia docket.

As the Daubert hearings started—named for the 1993 U.S. Supreme Court case Daubert v. Merrell Dow Pharmaceuticals that allows parties in the case to challenge expert testimony before the start of trial—the focus was on Berard, a professor at the University of Montreal who researches the effect of medications on pregnancy. She is an expert witness presented by the plaintiffs.

“The real issue for this court … hotly debated by both sides [is] when we’re talking about birth defects, is there a difference between SSRI drugs” or can you lump them together and treat them as a class, Sheila Birnbaum said last week during the hearings. Birnbaum is a partner with Quinn Emanuel Urquhart & Sullivan in New York who is on Pfizer’s defense team. She was referring to antidepressant drugs that operate as “selective serotonin reuptake inhibitors” and showed a slide that pictured the chemical compounds for five different SSRIs, including Paxil and Zoloft, all of which looked different.

“They’re very different,” Birnbaum said, building the defense’s argument that SSRI drugs can’t be treated as a class of medicines with shared characteristics and effects.

From the start of the litigation, said Quinn Emanuel lead defense lawyer Mark Cheffo, the plaintiffs have said, “‘We’re lumpers, we’re going to lump everything together’… and, frankly, Dr. Berard is a lumper as well.”

Berard maintains that a host of more than a dozen birth defects—from problems with the development of the heart to club feet—are attributable to Zoloft and similar SSRIs, Cheffo said at the hearing.

“What’s particularly troubling, well, troubling and instructive here, is that Dr. Berard looked at the same data that the world’s scientists and professional organizations and regulatory agencies have looked at, yet she’s come to the conclusion that Zoloft causes all of these birth defects, where all of the other scientists and professional organizations and regulatory agencies have determined that it doesn’t even cause one of these birth defects,” Cheffo told Rufe and Rau at the start of the hearing last week. “It’s Dr. Berard against the world.”

In their bench memorandum urging the court to not impose limits on Berard’s testimony, the plaintiffs said, “A review of Dr. Berard’s deposition transcript shows that she did not ignore the studies cited by Pfizer, and in fact, she even attempted to explain why they neither contradict nor undermine her opinion.”

“Counsel for Pfizer, however, chose to ignore her explanations as to why those studies are flawed and why she discounted them. In fact, not only did Pfizer ignore her explanations, it made every effort to suppress them,” the plaintiffs said in their brief, quoting half-a-dozen pages of deposition testimony where the defense objected to Berard’s attempts to explain her reasoning.

Referring to the portion of the Federal Rules of Civil Procedure governing the disclosure of expert testimony, Pfizer argued in its bench brief, “‘Rule 26(a)(2) does not allow parties to cure deficient expert reports by supplementing them with later deposition testimony.’” It quoted from a 2008 opinion from the U.S. Court of Appeals for the Seventh Circuit in Ciomber v. Cooperative Plus.

“The Federal Rules were designed to avoid the unfair prejudice that is created by improperly disclosing, in the midst of a deposition or a hearing, new opinions and analyses that could and should have been included in an expert report—particularly where, as here, rebuttal reports were envisioned but not served,” Pfizer argued.

Saranac Hale Spencer can be contacted at 215-557-2449 or sspencer@alm.com. Follow her on Twitter @SSpencerTLI.