# Chronic Use of Abemaciclib Leading to Breathlessness and Demise: A Case Report

## TL;DR

An 82-year-old woman developed fatal lung complications after long-term use of abemaciclib, a cancer drug linked to a rare but deadly side effect called checkpoint inhibitor pneumonitis.

## Contribution

This case report highlights the rare but fatal risk of checkpoint inhibitor pneumonitis associated with abemaciclib use in cancer treatment.

## Key findings

- Chronic abemaciclib use led to checkpoint inhibitor pneumonitis and acute respiratory distress syndrome.
- The patient's condition progressed to respiratory failure and eventual demise despite hospitalization.
- Early recognition and specialist involvement may be critical to reduce mortality from this rare complication.

## Abstract

Checkpoint inhibitor pneumonitis (CIP) is a potentially fatal disease that can occur at any duration of treatment. Patients may present with vague respiratory symptoms such as progressive cough, dyspnea, and decreased activity tolerance. Among checkpoint inhibitors, CIP is higher in programmed death 1 (PD-1) inhibitors.

An 82-year-old Latina woman with estrogen receptor (ER)-positive human epidermal growth factor receptor (HER)-2-negative lobular carcinoma of the right breast had been treated by partial mastectomy followed by adjuvant hormonal treatment and radiation in 2014. Then CMF (cyclophosphamide, methotrexate, and 5-fluorouracil) was followed by letrozole and abemaciclib, PD-1, therapy in 2022. In 2023, the patient presented with a dry cough and worsening dyspnea with a new oxygen requirement. She was admitted to the hospital with a diagnosis of multifocal pneumonia and sepsis. She unfortunately developed rapidly higher oxygen requirements and acute respiratory distress syndrome (ARDS) and was ultimately presumed to have CIP. She was intubated on hospital day 6 and extubated on day 12 with no plans for reintubation and do-not-resuscitate status. She subsequently had demise after a period of respiratory arrest.

CIP is rare but associated with fatal outcomes, especially with the development of ARDS. It is important, along the course of cancer treatment and goals of care discussion, to educate patients and their families on possible side effects of chemotherapy and involve specialists early with the goal of lowering mortality rates. Most patients do not survive this unfortunate progression of disease.