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Clinical trial data may not apply to real-world patients with kidney cancer
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Patients with metastatic renal cell cancer tend to be sicker and older in a real-world setting than patients enrolled on clinical trials, according to results of a cohort study.
Further, 39% of patients with renal cell carcinoma treated with the four most common tyrosine kinase inhibitors would be ineligible for phase 3 trials, making study data inapplicable to this population, according to the researchers.
Aaron P. Mitchell
“There are a lot of standard reasons why patients would be excluded from a clinical trial, but if a person will be getting the drugs in a clinical setting it is important to know if they can expect to see the same benefits or if they might experience more dangerous side effects,” Aaron P. Mitchell, MD, a hematology/oncology fellow at University of North Carolina Medical Center, said in a press release. “Physicians can’t know for sure because the trial data do not directly apply.”
Mitchell and colleagues retrospectively analyzed data from patients with metastatic renal cell cancer treated between January 2007 and May 2011 in routine oncology practices within the Duke University Health System and the ACORN network of 16 community oncology practices. This cohort included 438 patients who received the mTOR inhibitor temsirolimus (Torisel, Pfizer) or TKIs sunitinib (Sutent, Pfizer), sorafenib (Nexavar, Bayer) or pazopanib (Votrient, Novartis) as first-line treatment.
Researchers compared these patients to those enrolled onto phase 3 clinical trials that led to FDA approval of targeted therapies for metastatic renal cell carcinoma.
Patients in the real-world setting appeared more likely to have poor-risk disease based on Memorial Sloan Kettering Cancer Center criteria (7.4% vs. 2.9%; P < .001) and less likely to have favorable-risk disease (30.1% vs. 43.8%; P < .001). However, patients who received temsirolimus were less likely to have poor-risk disease (poor, 10.2% vs. 69.4%; P < .001; favorable, 16.9% vs. 0%; P < .001).
More real-world patients also had a worse performance status (ECOG > 1, 11.1% vs. 0.6%; P < .001).
Thirty-nine percent of patients would have been excluded from a phase 3 trial that evaluated the drug they received in the real-world setting.
The burden should not be on clinicians to examine trial data more critically, but rather for the clinical trials to be more inclusive of patients, according to Mitchell.
“Pharmaceutical companies are designing trials so they are more expedient,” Mitchell said in the release. “If they are being asked to enroll sicker patients, they will have to enroll more patients, making the trials much more expensive.
“So, in effect, you’re asking the pharmaceutical company to invest more resources when the outcome for them will largely be the same because, as we’ve found, the drugs are being prescribed regardless.”
Rather than have FDA approval stand as the endpoint to prove a drug’s efficacy, there should be greater emphasis on post-marking data collection and analysis, Mitchell said.
“There is a lot of talk about the need to continue studying these drugs even after they have crossed that approval finish line and are being used,” Mitchell said in a statement. “We should do a better job of making sure we’re still seeing beneficial results and not unintended side effects.” – by Anthony SanFilippo
Disclosure: Mitchell reports no relevant financial disclosures. Please see the full study for a list of all other researchers’ relevant financial disclosures.
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