Yet Another Retraction for Potti Cancer Gene Research

Roxanne Nelson

August 24, 2011

August 24, 2011 — The countdown continues…beleaguered researcher Anil Potti, MD, has had yet another paper retracted. This time, his coauthors have retracted a 2006 study from Blood, citing an inability to reproduce the results that were performed independently by the first author, Anil Potti, regarding validation of predictive models for thrombotic phenotypes (Blood. 2006;107:1391-1396).

The list of retracted Potti papers has now mushroomed to 5, and the Blood paper now joins studies that were published in the Journal of Clinical Oncology, Nature Medicine, The Lancet Oncology, and the New England Journal of Medicine.

As previously reported by Medscape Medical News, Dr. Potti resigned from his position at Duke University’s Institute for Genome Sciences and Policy and the School of Medicine in November 2010, which was 4 months after the university began investigating his work and credentials and placed him on paid administrative leave.

These investigations followed publication of an article in the Cancer Letter, which reported that he overstated his academic achievements by claiming to be a Rhodes Scholar.

When questions about Dr. Potti's credentials became public, the American Cancer Society suspended payment of a $729,000 grant that it had awarded to him to study lung cancer genetics. The grant was given to him on the basis of his resume, which had listed being a recipient of the Rhodes scholarship.

In addition, Eli Lilly and Company and CancerGuide Diagnostics terminated their relationships with Dr. Potti, a few months after the article appeared in the Cancer Letter. CancerGuide, a private company that markets and develops molecular oncology assays, had licensed technology based on Dr. Potti’s research, according to an article published last year in the Duke Chronicle.

Dr. Potti's research was directed at developing gene-expression signatures that predict responses to various cytotoxic chemotherapeutic drugs. The goal of this research was to identify characteristics of individual patients that could be matched with specific therapeutic agents. His published papers reported that the signatures identified in his lab had the capacity to predict therapeutic response. When this work was first reported, it was enthusiastically welcomed by cancer experts.

This research also led to the initiation of several large clinical trials sponsored by the National Cancer Institute, which were halted when questions about reproducibility of the results were raised.

Two biostatisticians from M.D. Anderson Cancer Center in Houston, Texas — Keith Baggerly, PhD, and Kevin Coombes, PhD — attempted to reproduce Dr. Potti's findings at the request of investigators from their institution. However, they were unable to replicate the results.

Blood Retraction

The most recent retraction was issued on August 19, for a study that appeared in the February 15, 2006, issue of Blood: "Gene-expression Patterns Predict Phenotypes of Immune-Mediated Thrombosis."

In their retraction letter, the authors note that "It has also been recognized that multiple samples appear to be duplicated in the training and validation datasets pertaining to the analysis presented in Figure 2 of the paper, which was also performed by Anil Potti. Since these results are fundamental to the conclusions of the paper, the authors formally retract the paper. The authors deeply regret the impact of this action on the work of other investigators and apologize to the readers, reviewers, and editors of Blood."

According to the blog Retraction Watch, the Blood paper has been cited 24 times.

Dr. Potti is currently employed by the Coastal Cancer Center, an oncology practice with 4 offices in South Carolina and 1 in North Carolina. His biography on the Coastal Cancer Center Web site does not mention whether he will continue to be involved in research in his new job or that he was a recipient of a Rhodes Scholarship.

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