Pembrolizumab-Induced Smoldering Myocarditis in Patients With Triple-Negative Breast Cancer

Area of Science:

• Cardiology
• Oncology
• Immunology

Background:

• Immune checkpoint inhibitors (ICIs) combined with chemotherapy are approved for treating triple-negative breast cancer (TNBC).
• ICI-induced myocarditis is a rare but serious complication with high mortality.
• Diagnosing ICI-induced myocarditis is difficult due to varied presentations and disease severity.

Observation:

• Smoldering myocarditis (SM) is a subclinical form of myocarditis, presenting with asymptomatic or mild, nonspecific symptoms.
• There is a lack of data on the incidence, characteristics, and outcomes of ICI-induced SM in TNBC patients.
• This study presents two cases of pembrolizumab-induced smoldering myocarditis in TNBC patients undergoing ICI therapy.

Findings:

• The cases highlight the occurrence of subclinical myocarditis in TNBC patients treated with pembrolizumab.
• These instances suggest that smoldering myocarditis may be an underrecognized complication in this patient population.
• Further investigation is needed to understand the full spectrum of ICI-induced cardiac toxicity in TNBC.

Implications:

• Recognizing smoldering myocarditis is crucial for early detection and management of ICI-related cardiac events in TNBC.
• This finding may prompt closer cardiac monitoring in TNBC patients receiving ICIs, even in the absence of overt symptoms.
• Understanding ICI-induced smoldering myocarditis can lead to improved patient outcomes and safer cancer treatment strategies.