Acute presentations in neoadjuvant chemotherapy/immune checkpoint inhibition for triple negative breast cancer: experiences and impact from real-world data.

Background: Recent data showed benefit of the addition of immune checkpoint inhibitor (ICI) therapy to cytotoxic chemotherapy in the neoadjuvant setting for patients with early triple negative breast cancer. Acute presentations in patients treated with ICI therapy and combined chemotherapy/ICI therapy can be challenging and have significant resource implications.

Materials And Methods: A prospective analysis was performed at a specialist oncology hospital in England from December 1, 2022 to December 31, 2024. The primary outcome measure was whether the acute presentation was due to an ICI-related toxicity. Secondary outcome measures were number of inpatient bed days and the proportion of patients with grade ≥3 diarrhoea or transaminases that were diagnosed with ICI-related toxicity.

Results: During the study period, 285 patients were treated with neoadjuvant PC-EC/Pembro for triple negative breast cancer with 210 emergency presentations in 168 patients to the acute floor. Fifty-three (25.2 %) patients were diagnosed with an ICI-related toxicity of which 5 were a relapsed/recurrent presentation. One hundred and nine patients (51.9 %) were discharged on the day of presentation. A total of 576 inpatient bed days were used in the management of the cohort. Sixteen (7.6 %) patients had grade 3 diarrhoea at presentation; only 5 (31.3 %) of these were ICI-mediated. Eleven (5.2 %) patients had a grade ≥3 ALT rise at presentation; only 3 (27.2 %) of these were ICI-mediated.

Conclusion: In triple negative breast cancer being treated in the neoadjuvant setting with chemotherapy/immune checkpoint inhibition only 25.2 % of acute presentations had an ICI-related toxicity driving their attendance. Toxicities in this cohort may require a different approach to those treated with chemotherapy or ICI alone and may necessitate new clinical practice guidance.