"Tafamidis is an astonishingly effective drug," Dr. Rodney Falk of Brigham and Women's Hospital in Boston told Reuters Health by phone. "The big problem is it's a highly effective drug at a ridiculous price. Some European countries and South American countries have the drug but are not allowed to prescribe it because of the price."
Patients taking the high-priced drug "want to know that it's working," Dr. Falk said, and "it's very encouraging" for them to hear, "'Yes, we see a change.'"
The Pfizer drug, sold as Vyndaqel, was approved in the United Stated in 2019 with a list price of $225,000 per year.
"We wrote a letter last year describing the real-world cost for 80 patients, including copayments of around $2,000 a month for 51 of them," Dr. Falk said. "Nine decided not to start the drug because even after copayment assistance, they still would have had to pay more than $1,000 per month." (https://bit.ly/3GyY0YW)
"The solution is that in a couple of years, the drug will go generic," he added. "And there's another stabilizer in trials now. When you have two drugs on the market, you've got to bring the price down."
As reported in JACC: CardioOncology, Dr. Falk and colleagues studied data from 72 non-trial, unselected patients with ATTR cardiomyopathy (mean age, 79; 67 with wild-type and five with variant TTR). TTR levels were measured before therapy and three to 12 months following initiation of tafamidis.
Tafamidis administration increased serum TTR from a mean of 21.8 mg/dl to 29.3 mg/dL, an increase of 34.5%. In five patients with variant TTR, the increase was 70.9%, compared to 32.0% in the wild-type patients.
Mean N-terminal pro-brain natriuretic peptide increased over a mean follow-up of 21 weeks, but the change was not statistically significant. Similarly, there was a small increase in high-sensitivity troponin T that was of borderline statistical significance.
The authors conclude, "Tafamidis consistently increases serum TTR levels in patients with ATTR cardiomyopathy, consistent with its effect on stabilizing TTR. Measurement of TTR level change post-TTR stabilizing therapy might be a surrogate for stabilization and could be a more accurate measure of drug efficacy than an in vitro nonphysiologic test of stabilization."
Dr. Falk added, "What we don't know is whether the percentage increase correlates with the efficacy of the drug. For example, if you go up 70%, are you more likely in two years time to be feeling perfectly fine, but not if the change in levels is, say, 20%? That's a question for future research."
Dr. Martha Grogan of Mayo Clinic, Rochester, coauthor of a related editorial, commented in an email to Reuters Health, "Treatment with tafamidis definitely warranted, despite the potential financial toxicity!"
Like Dr. Falk, she noted, "We hope that competition in the marketplace will help bring down the cost. It is very challenging for patients and providers to understand that we have such an expensive medication but there is not an easy way of knowing whether not it is working."
"The bottom line is that with the advent of tafamidis treatment, wild-type transthyretin cardiac amyloidosis is no longer an academic disease - one in which we make the diagnosis only out of interest but have nothing to offer," she said. "This is now a treatable condition."
"The editorial was focused on the prealbumin level, which is a simple test," she said. "Tafamidis increases the prealbumin level and it seems as if it stays pretty stable once it has increased. It is important for providers and patients not to focus on expensive cardiac imaging tests such as frequent echocardiograms or MRI, if that is not going to change the treatment provided. Doing a lot of follow-up cardiac imaging tests will only add to the burden of healthcare costs."
"I tell patients I am most concerned about they feel, how far can they walk without becoming short of breath, how often they are in the hospital or needing an adjustment of diuretic therapy," she said. "Those factors along with some simple blood tests are usually the best ways to follow patients with TTR amyloid."
Tafamidis is produced by Pfizer. Dr. Falk and two coauthors have received funding from Pfizer, as has Dr. Grogan.
SOURCE: https://bit.ly/3boOs4y JACC: CardioOncology, online October 3, 2021.
By Marilynn Larkin
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