To the editor:

We were heartened to see that Nature Medicine chose to cover the National Institutes of Health (NIH) Recombinant DNA Advisory Committee (RAC)'s review of the death of Jolee Mohr, which occurred while she was enrolled in a gene therapy trial1, but we are concerned that the article did not reflect the panel's discussion and conclusions.

The RAC committee members were mindful of the dangers of drawing definitive conclusions on the basis of limited information and did not declare a cause of death in the case. Still, the data they were presented with clearly showed that the amount of gene therapy product outside the knee—where it was injected and where it was designed to remain—was negligible. Instead, the panel was presented with extensive evidence that systemic antiarthritis immunosuppressants, which Mohr was also taking, have been definitively linked to opportunistic infections such as the histoplasmosis that contributed to her death.

Yet the article, in quoting a witness who was neither a member of the blue-ribbon NIH committee nor an immunologist or rheumatologist, gave the impression that the gene therapy Mohr received remains a prime candidate for a cause of death, a supposition that was not borne out by the evidence shown at the meeting.

We are also concerned that the headline, “Poor trial design leaves gene therapy death a mystery,” suggests that the phase 1/2 trial of our therapy for rheumatoid arthritis was not designed according to current good practices because patients were permitted to use other arthritis drugs. Yet continuance of maintenance therapy has been a mainstay of trial design in this or any field. This protocol underwent a most rigorous screening process and was evaluated not only by leading rheumatologists and the institutions that performed the research, but also by the NIH itself. Indeed, the assertion that the trial design was flawed was never made by any member of the RAC during the meeting, so the claim that this was an official outcome of the meeting is troublesome.

Mohr's death was a tragedy. We at Targeted Genetics have made every effort to assist the doctors, pathologists, researchers and regulatory bodies who are seeking to better understand why she died. We respect the conclusions of the NIH's expert panel, which reviewed all the available information and cast no aspersions on the gene therapy product, and we hope that their measured assessment will receive more prominent mention in the future.