Several observational studies published recently highlighted the value of continued vigilance of pharmaceuticals after FDA approval. One looked at the side effects of statins and the other at the cardiotoxic effect of two chemotherapy drugs for treating invasive breast cancer.
In both cases, investigators had conducted randomized clinical trials that demonstrated the efficacy and safety of the pharmaceuticals, evidence that was used to win FDA approval. The trials also provided valuable information about risks. In the context of breast cancer treatments, higher risks may be acceptable given the mortality risk.
As Bowles et al pointed out in their paper, clinical trial data on the chemotherapy drugs anthracycline and trastuzumab indicated that the drugs were associated with an increase in heart failure or cardiomyopathy of 2 percent and 4 percent, respectively. That knowledge helped to develop protocols that included regular monitoring of cardiac function in women who received the therapies.
The findings by Bowles et al suggested real-world use of the drugs may have higher risks than was found in the trials. They calculated that women who received anthracycline followed by trastuzumab had a sevenfold increase in the risk of heart failure or cardiomyopathy. They also found that the majority of women who received the sequential treatment were younger. Another point of note: the women had incident invasive cancers that were either local or regional.
The statin study, on the other hand, helped to reinforce the association between statin potency and muscle-related side effects. Rosuvastatin had a higher risk rate for these side effects than five other leading statins in an analysis of seven years of FDA adverse case reports. The authors recommended that physicians keep that in mind when prescribing statins to manage dyslipidemia.
For cardiologists, both findings should prove useful. Patients who can’t tolerate a statin’s side effects are more likely to stop taking their prescribed dose, increasing their risk of adverse cardiovascular events. And knowing the risks associated with anthracycline and trastuzumab treatment may allow cardiologists to diagnose heart failure or cardiomyopathy sooner in patients with a history of treatments with these chemotherapies.
Authors of both studies emphasized that randomized clinical trials are the gold standard. But as observational studies show, investigation shouldn’t stop after regulators approve a drug.
Cardiovascular Business, editor