Use of Cyclin-Dependent Kinase 4 and 6 Inhibitors in the Setting of Visceral Crisis

Overall survival (OS) in patients with either endocrine-sensitive or -resistant disease who are not in visceral crisis has been improved by the combination of CDK4/6 inhibitors and endocrine therapy. Among patients with hormone receptor (HR)-positive/HER2-negative metastatic breast cancer who present with visceral crisis at diagnosis, a retrospective analysis of real-world data was used to assess the efficacy of CDK4/6 inhibitors.

Researchers identified 5966 patients who had been diagnosed with HR-positive/HER2-negative metastatic breast cancer between 2015 and 2020. All comparisons of survival were used to perform propensity score matching. Visceral crisis was defined as either liver metastases with liver dysfunction, lymphangitis with dyspnea, or the presence of pancytopenia. Fifteen percent of patients (N = 906) received treatment with CDK4/6 inhibitor therapy.

Patients who received treatment with CDK4/6 inhibitors had a significantly improved (P = .0002) median OS of 59.6 months compared with 46.2 months for patients who did not receive CDK4/6 inhibitor therapy. This contrast between the CDK4/6 inhibitor and non–CDK4/6 inhibitor groups was consistent for 2-year OS scores, as well (71.6% vs 61.4%, respectively).

OS was significantly different among patients who received CDK4/6 inhibitors as a first-line therapy compared with another treatment (P <.0001), with a median OS of 59.6 months compared with 41.5 months, respectively.

The analysis included 336 patients who had been diagnosed with HR-positive metastatic breast cancer who at the time of diagnosis presented with visceral crisis. Sixty-one of these patients (18%) received first-line CDK4/6 inhibitor therapy.

The median OS of patients who did and those who did not have visceral crisis at diagnosis and received treatment was 8.1 months and 210 months, respectively. After initial treatment, the OS significantly differed among patients with visceral crisis who did and those who did not receive treatment with CDK4/6 inhibitors (P = .01), with 2-year OS at 26.1% and 8.1% and median OS at 11 months and 6 months, respectively.

The investigators concluded that treatment with CDK4/6 inhibitors in the presence of visceral crisis at diagnosis was linked with an improvement in OS of 5 months when compared with patients treated with chemotherapy. Further studies exploring the use of CDK4/6 inhibitors in the setting of visceral crisis are warranted in future clinical trials.

Source:

Dawood SS, Brzozowski K. Efficacy of CDK4/6i in the visceral crisis setting: results from a real-world database. Presented at: American Society of Clinical Oncology 2021 Annual Meeting, June 4-8. Abstract 1047.