Case Notes

During this same time period, Maxx's doctor prescribed for him a second drug, the tumor necrosis factor alfa antagonist (anti-TNF) drug infliximab, marketed as Remicade. Anti-TNF drugs are approved to treat a number of autoimmune disorders, such as Crohn's disease and rheumatoid arthritis. When Maxx's IBD went into remission in 2006, his doctor took him off of Remicade. Two months later, the FDA approved a new label for Remicade that included a warning that development of HSTCL — a rare form of non-Hodgkin's lymphoma — had been observed in young male patients taking both Remicade and a thiopurine, such as 6-MP. When the label change was made, Remicade's manufacturer, Centicor, sent “Dear Health Care Provider” letters to prescribers to alert them to the new warning.

When Maxx's IBS symptoms later returned, his doctor put him on another anti-TNF drug, Humira, which at that time did not come with a warning about development of HSTCL. At age 20, Maxx was diagnosed with HSTCL. He died within six months of that disease.

Maxx's parents brought suit against several drug manufacturers, settling with most of them prior to trial. The U.S. District Court for the Northern District of California then dismissed the case on motion for summary judgment after concluding, inter alia, that the plaintiffs' experts' causation testimony was not reliable under the Daubert standard and was therefore inadmissible under Federal Rule of Evidence 702. The bases for this ruling were that the plaintiffs' two medical experts developed their opinions specifically for litigation, and they had never conducted independent research on the relationship between 6-MP and anti-TNF drugs and the development of HSTCL. Both experts also admitted that their conclusions about the relationship between 6-MP and anti-TNF drugs causing HSTCL would not satisfy the standards required for publication in peer-reviewed medical journals.

The district court concluded that the experts' lack of independent research combined with their reluctance to publish, “casts doubt [on] the reliability of their methodologies under Rule 702.” Added to this, the district court observed that more than 70% of HSTCL cases are idiopathic, so the lack of animal or epidemiological studies showing a causal link between HSTCL and the drug combination of 6-MP and anti TNF drugs made it, in the district court's opinion, impossible for the proffered experts to “reasonably eliminate other potential causes of Maxx's HSTCL.” After granting the defense's motion for summary judgment, the district court denied the plaintiffs' motion for reconsideration. The plaintiffs appealed to the Ninth Circuit.

While noting that the case had presented “a close question,” the court nevertheless reversed, finding that the district court incorrectly put too much weight on the facts that the experts formed their opinions when researching for this litigation and had not been published on the subject at hand. “While independent research into the topic at issue is helpful to establish reliability, its absence does not mean the experts' methods were unreliable,” said the court. Instead, an expert is permitted to use other means of showing that his conclusions are based on sound scientific grounds. The proffered experts had done that. The court was impressed with the lengthy and distinguished medical careers of the plaintiffs' two proffered experts, to include their close observations of multiple patients with non-Hodgkin's lymphoma, as well as their teaching and medical research credentials.

One of the doctors opined that there was a one in six million chance that Maxx would have developed HSTCL without exposure to the drugs he ingested to treat IBS, and therefore it was likely his explosure to these substances caused the lymphoma. The other doctor used similar logic to conclude that Maxx likely contracted lymphoma through exposure to the drugs.

The Ninth Circuit also chided the district court for conflating the standards for publication in a peer-reviewed journal with the standards for admitting expert testimony in a courtroom. The district court had found a lack of rigorous scientific analysis from the fact that the experts admitted they would not be willing to publish their opinions about the correlation between taking the drugs that Maxx took and contracting HSTCL. The reasons the experts gave for their reticence were that they had no new data to contribute to the scientific dialogue, and any meta-analysis or review of the literature could only be published upon invitation. But opinions need not be published or publishable; the fact that they are not can go to the weight a jury assigns them, the appeals court concluded.

Because “the district court looked too narrowly at each individual consideration, without taking into account the broader picture of the experts' overall methodology,” and it “improperly ignored the experts' experience, reliance on a variety of literature and studies, and review of Maxx's medical records and history, as well as the fundamental importance of differential diagnosis by experienced doctors treating troubled patients,” the Ninth Circuit found that the experts' testimony should have been admitted. For this and other reasons, the appeals court reversed and remanded the case to the district court.