Treatment of Transthyretin Amyloid Cardiomyopathy: The Current Options, the Future, and the Challenges

Transthyretin amyloid cardiomyopathy (ATTR-CM) is a progressively debilitating, rare disease associated with high mortality. ATTR-CM occurs when TTR amyloid protein builds up in the myocardium along with different organs, most commonly the peripheral and the autonomic nervous systems. Managing the cardiac complications with standard heart failure medications is difficult due to the challenge to maintain a balance between the high filling pressure associated with restricted ventricular volume and the low cardiac output. To date, tafamidis is the only agent approved for ATTR-CM treatment. Besides, several agents, including green tea, tolcapone, and diflunisal, are used off-label in ATTR-CM patients. Novel therapies using RNA interference also offer clinical promise. Patisiran and inotersen are currently approved for ATTR-polyneuropathy of hereditary origin and are under investigation for ATTR-CM. Monoclonal antibodies in the early development phases carry hope for amyloid deposit clearance. Despite several drug candidates in the clinical development pipeline, the small ATTR-CM patient population raises several challenges. This review describes current and future therapies for ATTR-CM and sheds light on the clinical development hurdles facing them.

Annual Cardiovascular-Related Hospitalization Days Avoided with Tafamidis in Patients with Transthyretin Amyloid Cardiomyopathy

BACKGROUND

Patients with transthyretin amyloid cardiomyopathy (ATTR-CM) experience infiltrative cardiomyopathy and heart failure symptoms requiring costly hospitalizations. The Transthyretin Amyloidosis Cardiomyopathy Clinical Trial (ATTR-ACT) demonstrated the efficacy of tafamidis on the frequency of cardiovascular (CV)-related hospitalizations in patients with ATTR-CM.

PURPOSE

As length of stay can affect the total hospitalization burden, our study aimed to better understand the impact of tafamidis on the number of CV-related hospital days avoided in the management of ATTR-CM patients.

METHODS

Data from ATTR-ACT were used to calculate the total burden of CV-related hospitalization (days) by treatment arm in this post hoc analysis.

RESULTS

In the total trial population, patients receiving tafamidis had significantly fewer CV-related hospitalizations per year (relative risk reduction [RRR] 0.68; 0.4750 vs. 0.7025, p < 0.0001) and a shorter mean length of stay per CV-related hospitalization event (8.6250 vs. 9.5625 days) than patients receiving placebo. Taken together, tafamidis prevented 2.62 CV-related hospitalization days per patient per year. A subgroup analysis showed that with earlier treatment initiation of tafamidis, the annual number of CV-related hospitalizations was significantly lowered by 52% compared with placebo (RRR 0.48; 0.3378 vs. 0.7091, p < 0.0001). With 1.14 fewer days per hospitalization, tafamidis reduced the annual number of CV-related hospitalization days by 3.96 days per New York Heart Association class I/II patient.

CONCLUSIONS

In patients with ATTR-CM, tafamidis was associated with a lower rate of CV-related hospitalizations and shorter length of hospital stay. Timely diagnosis and treatment with tafamidis could further decrease the total number of CV-related hospitalization days per year.

CLINICALTRIALS

GOV IDENTIFIER

NCT01994889.