Prediction of Severe Neutropenia and Diarrhoea in Breast Cancer Patients Treated with Abemaciclib

HPS Pharmacies is delighted to share the following study overview written by Natansh Modi, a pharmacist at HPS Pharmacies St Andrew’s. The study, conducted by Natansh and her colleagues looked at side effects in breast cancer patients treated with abemaciclib. Click here to read the published study.

1. What was the main purpose of your study?

The study aimed to develop clinical prediction models that allows for personalised predictions of diarrhoea and neutropenia following abemaciclib initiation.

2. What was the rationale behind the study? Why is it important to do research on this topic?

Abemaciclib is a novel cyclin-dependent kinase (CDK) 4/6 reversible inhibitor that is used in the treatment of hormone receptor-positive/human epidermal growth factor 2-negative (HR+/HER2-) advanced breast cancer (ABC). Current guidelines support the use of abemaciclib as a first-line therapy either in combination with a non-steroidal aromatase inhibitor (NSAI) or fulvestrant in patients with HR+/HER2-ABC. Safety data emerging from the clinical trials have identified diarrhoea and neutropenia (characterised by low neutrophil count) as key side effects associated with abemaciclib use.

The regulatory approval and existing literature present limited information about risk factors associated with developing diarrhoea and neutropenia in patients initiating abemaciclib. Valid prediction models can enable clinicians to understand patients needing increased monitoring or pre-emptive strategies to manage toxicities – ultimately allowing patients to remain on beneficial treatments for longer.

3. What was the key finding of your study?

The study identified that advanced age (70 years and above) was associated with an increased risk of abemaciclib induced grade ≥ 3 diarrhoea.

The study used large, pooled data to develop and present the first clinical prediction tool of abemaciclib induced grade ≥3 neutropenia in patients with HR+/HER2- ABC. The tool defined the risk of grade ≥3 neutropenia, which ranged from 5% to 64% according to patient race (Asian vs non-Asian), Eastern Cooperative Oncology Group performance status (ECOGPS) (1+ vs 0) and pre-treatment white blood cell count (<4.0 vs 4.0–4.99 vs 5.0–6.5 vs ≥ 6.5 × 10⁹/L).

4. What are the implications of your findings for patient care?

Effective communication of personalised and well-validated predictions of an individual’s expected adverse outcomes can improve shared decision making, empower patients, and enable patients and clinicians to make better decisions regarding strategies to mitigate adverse outcomes.

5. What are the key limitations of your study?

Randomised control trials (RCTs) are the backbone of evidence-based medicine, however, strict inclusion criteria within RCTs can limit the generalisability of results.

6. What are the next steps?

With advances in large electronic health record platforms, future opportunities to externally validate the presented tool within observational datasets of patients using abemaciclib in routine clinical care should occur – in the future, this may also include evaluating the tools appropriateness for abemaciclib’s use as a neo-adjuvant treatment.