GU cancer

Oncology drug real world outcomes don’t match RCT results

New cancer drugs are less effective in real world settings than the results from the randomised controlled trials used to support their approval, US research shows.

A review of outcomes for nine cancer drugs approved since 2008 for 14 indications found that overall survival (OS) rates in 2196 Medicare-eligible patients over the age of 65 were on average seven months less than those seen in the clinical trials that led to FDA approval of the drugs.

Median overall survival was inferior for all but one (pemetrexed) of the nine drugs in Medicare patients compared to the pivotal clinical trials (median difference -7.4 months, range +4.2 to 28.7 months), according to the analysis by researchers led by Dr Angela Green of the Gynecologic Medical Oncology Service, Memorial Sloan Kettering Cancer Center.

Duration of treatment in real world settings was also lower than in clinical trials (median difference -3 months, range 0.8 to 9 months) for all but one indication

The analysis covered drugs including everolimus for advanced ER+ HER2 breast cancer; erlotinib and pemetrexed maintenance therapy for advanced NSCLC; enzalutamide, cabazitaxel and abiraterone for advanced castration-resistant prostate cancer and axitinib, everolimus and pazopanib for advanced renal cell carcinoma.

The shorter duration of treatment among Medicare patients could reflect treatment toxicity and might explain survival differences, the researchers said.

They noted that 16% of patients receiving oral drugs had dose reductions, ranging from none for enzalutamide in CRPC to 41% of patients receiving everolimus.

In addition, Medicare-eligible cancer patients tended to be older (72 vs 64 years) and have a lower proportion of males (56% vs 69%) than the cohorts in clinical trials.

Trials used to obtain regulatory approval may not be generalisable to cancer patients in real world settings who may be older and more frail than those eligible for research studies, they concluded

“These findings suggest that pivotal clinical trials leading to regulatory approval do not accurately predict clinical outcomes for Medicare patients who are eligible for treatment,” they said.

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