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NIH Exceptional Responders to Cancer Therapy Study

 

In treating patients with cancer, unexpected and prolonged remissions following standard therapy can be observed; the reasons why certain patients experience these remissions have been unclear. If molecular markers could be developed that predict positive responses to certain therapies, even in a small subset of patients, it might be possible to more effectively choose treatment programs for individual patients.

 

According to the NIH, the Exceptional Responders Initiative (ERI), a study to investigate the molecular factors of tumors associated with exceptional treatment responses of cancer patients to drug therapies, was launched by the National Cancer Institute (NCI). In this program, the NCI will attempt to identify the molecular features of tumors that predict whether or not a particular drug or class of drugs will be beneficial. Investigators will examine tumor specimens from patients in clinical trials who achieved an exceptional response relative to other trial participants, or other patients who achieved an exceptional and unexpected response to a non-investigational therapy.

 

This initiative was initially considered two years ago when, through the use of advanced DNA sequencing methods, the molecular basis for the prolonged remission of bladder cancer in a patient following treatment with a molecularly targeted drug in a clinical trial was determined. Based on this single and perhaps profound observation, it was proposed that it was a good idea to understand the mechanism of drug response for a relatively small number of patients in early phase clinical trials who benefit dramatically from therapy. In the past, trials in which up to only 10% of patients had significant and prolonged responses were considered unsuccessful, as it was not possible to understand why some patients benefitted from treatment and others did not.

 

In the ERI, some of the tissue and clinical data from exceptional responders will be obtained from NCI-supported trials as well as potentially other clinical trials. The remaining samples and data will come from standard therapy settings, such as community practice, where there are reliable outcome data, and from pharmaceutical industry trials or other sources. Consequently, letters of solicitation are being sent to cancer centers and others clinicians nationwide to ask them to assist in this effort. DNA and RNA from tissue samples will be isolated at the Biospecimen Core Resource at Nationwide Children’s Hospital, Columbus, Ohio, and those isolates will then be shipped to a DNA sequencing and analysis center at Baylor University, Houston.

 

Ultimately, this information could be used to identify patients who may potentially respond to agents with the same or similar mechanism of action. It may be difficult to determine if abnormalities found in exceptional responders are functionally significant and whether the abnormalities actually drive tumor growth. Additionally, relevant mutations may be present in less than 5% of tumors, making them difficult to identify. The study will also examine the feasibility of conducting a larger exceptional responder study (especially given what is expected to be a limited amount of tissue that can be collected over the study period of three to four years). The output of this initiative might include a list of plausible mutations, possible mutations, or simply all the mutations found in the exceptional responder cases. In addition, it is hoped that other investigators will seek to build on the data generated by this study by testing hypotheses on specimens from a trial that used a particular drug, or by comparing their own dataset with the shared data. Placing the full genomic annotation of 100 cases of exceptional responders in the public domain should aid all clinicians and researchers looking for patterns in drug response.

 

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