No malicious intent
“There are likely some that might lean toward not wanting to attribute blame to a new drug when the drug is in a study, but I really think that the leading factor is lack of awareness,” Dr. Addison said. “I’ve talked with several cancer collaborators around the country who run large clinical trials, and I think often, when an event may be brought to someone’s attention, there is a tendency to just write it off as kind of a generic expected event due to age, or just something that’s not really pertinent to the study. So they don’t really focus on it as much.”
“Closer collaboration between cardiologists and cancer physicians is needed to better determine true cardiac risks among patients treated with these drugs.”
Breast cancer oncologist Marc E. Lippman, MD, of Georgetown University Medical Center and Georgetown Lombardi Comprehensive Cancer Center, Washington, D.C., isn’t convinced a lack of awareness is the culprit.
“I don’t agree with that at all,” he said in an interview. “I think there are very, very clear rules and guidelines these days for adverse-event reporting. I think that’s not a very likely explanation – that it’s not on the radar.”
Part of the problem may be that some of the toxicities, particularly cardiovascular, may not emerge for years, he said. Participant screening for the trials also likely removed patients with high cardiovascular risk. “It’s very understandable to me – I’m not saying it’s good particularly – but I think it’s very understandable that, if you’re trying to develop a drug, the last thing you’d want to have is a lot of toxicity that you might have avoided by just being restrictive in who you let into the study,” Dr. Lippman said.
The underreported CVD events may also reflect the rapidly changing profile of cardiovascular toxicities associated with novel anticancer therapies.
“Providers, both cancer and noncancer, generally put cardiotoxicity in the box of anthracyclines and radiation, but particularly over the last decade, we’ve begun to understand it’s well beyond any one class of drugs,” Dr. Addison said.
“I agree completely,” Dr. Lippman said. For example, “the checkpoint inhibitors are so unbelievably different in terms of their toxicities that many people simply didn’t even know what they were getting into at first.”
One size does not fit all
Javid Moslehi, MD, director of the cardio-oncology program at Vanderbilt University, Nashville, Tenn., said echocardiography – recommended to detect changes in left ventricular function in patients exposed to anthracyclines or targeted agents like trastuzumab (Herceptin) – isn’t enough to address today’s cancer therapy–related CVD events.
“Initial drugs like anthracyclines or Herceptin in cardio-oncology were associated with systolic cardiac dysfunction, whereas the majority of issues we see in the cardio-oncology clinics today are vascular, metabolic, arrhythmogenic, and inflammatory,” he said in an interview. “Echocardiography misses the big and increasingly complex picture.”
His group, for example, has been studying myocarditis associated with immunotherapies, but none of the clinical trials require screening or surveillance for myocarditis with a cardiac biomarker like troponin.
The group also recently identified 303 deaths in patients exposed to ibrutinib, a drug that revolutionized the treatment of several B-cell malignancies but is associated with higher rates of atrial fibrillation, which is also associated with increased bleeding risk. “So there’s a little bit of a double whammy there, given that we often treat atrial fibrillation with anticoagulation and where we can cause complications in patients,” Dr. Moslehi noted.
Although there needs to be closer collaboration between cardiologists and oncologists on individual trials, cardiologists also have to realize that oncology care has become very personalized, he suggested.
“What’s probably relevant for the breast cancer patient may not be relevant for the prostate cancer patient and their respective treatments,” Dr. Moslehi said. “So if we were to say, ‘every person should get an echo,’ that may be less relevant to the prostate cancer patient where treatments can cause vascular and metabolic perturbations or to the patient treated with immunotherapy who may have myocarditis, where many of the echos can be normal. There’s no one-size-fits-all for these things.”
Wearable technologies like smartwatches could play a role in improving the reporting of CVD events with novel therapies but a lot more research needs to be done to validate these tools, Dr. Addison said. “But as we continue on into the 21st century, this is going to expand and may potentially help us,” he added.
In the interim, better standardization is needed of the cardiovascular events reported in oncology trials, particularly the Common Terminology Criteria for Adverse Events (CTCAE), said Dr. Moslehi, who also serves as chair of the American Heart Association’s subcommittee on cardio-oncology.
“Cardiovascular definitions are not exactly uniform and are not consistent with what we in cardiology consider to be important or relevant,” he said. “So I think there needs to be better standardization of these definitions, specifically within the CTCAE, which is what the oncologists use to identify adverse events.”
In a linked, Dr. Lippman and cardiologist Nanette Bishopric, MD, of the Medstar Heart and Vascular Institute in Washington, D.C., suggested it may also be time to organize a consortium that can carry out “rigorous multicenter clinical investigations to evaluate the cardiotoxicity of emerging cancer treatments,” similar to the Thrombosis in Myocardial Infarction Study Group.
“The success of this consortium in pioneering and targeting multiple generations of drugs for the treatment of MI, involving tens of thousands of patients and thousands of collaborations across multiple national borders, is a model for how to move forward in providing the new hope of cancer cure without the trade-off of years lost to heart disease,” the editorialists concluded.
The study was supported in part by National Institutes of Health grants, including a K12-CA133250 grant to Dr. Addison. Dr. Bishopric reported being on the scientific board of C&C Biopharma. Dr. Lippman reports being on the board of directors of and holding stock in Seattle Genetics. Dr. Moslehi reported having served on advisory boards for Pfizer, Novartis, Bristol-Myers Squibb, Deciphera, Audentes Pharmaceuticals, Nektar, Takeda, Ipsen, Myokardia, AstraZeneca, GlaxoSmithKline, Intrexon, and Regeneron.
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