A phase I dose escalation and expansion trial of the next-generation oral SERD camizestrant in women with ER-positive, HER2-negative advanced breast cancer: SERENA-1 monotherapy results

Ann Oncol. 2024 Aug;35(8):707-717. doi: 10.1016/j.annonc.2024.04.012. Epub 2024 May 8.

Abstract

Background: SERENA-1 (NCT03616587) is a phase I, multi-part, open-label study of camizestrant in pre- and post-menopausal women with estrogen receptor-positive (ER+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer. Parts A and B aim to determine the safety and tolerability of camizestrant monotherapy and define doses for clinical evaluation.

Patients and methods: Women aged ≥18 years with metastatic or recurrent ER+, HER2- breast cancer, refractory (or intolerant) to therapy, were assigned 25 mg up to 450 mg once daily (QD; escalation) or 75, 150, or 300 mg QD (expansion). Safety and tolerability, antitumor efficacy, pharmacokinetics, and impact on mutations in the estrogen receptor gene (ESR1m) circulating tumor (ct)DNA levels were assessed.

Results: By 9 March 2021, 108 patients received camizestrant monotherapy at 25-450 mg doses. Of these, 93 (86.1%) experienced treatment-related adverse events (TRAEs), 82.4% of which were grade 1 or 2. The most common TRAEs were visual effects (56%), (sinus) bradycardia (44%), fatigue (26%), and nausea (15%). There were no TRAEs grade 3 or higher, or treatment-related serious adverse events at doses ≤150 mg. Median tmax was achieved ∼2-4 h post-dose at all doses investigated, with an estimated half-life of 20-23 h. Efficacy was observed at all doses investigated, including in patients with prior cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) and/or fulvestrant treatment, with and without baseline ESR1 mutations, and with visceral disease, including liver metastases.

Conclusions: Camizestrant is a next-generation oral selective ER antagonist and degrader (SERD) and pure ER antagonist with a tolerable safety profile. The pharmacokinetics profile supports once-daily dosing, with evidence of pharmacodynamic and clinical efficacy in heavily pre-treated patients, regardless of ESR1m. This study established 75-, 150-, and 300-mg QD doses for phase II testing (SERENA-2, NCT04214288 and SERENA-3, NCT04588298).

Keywords: ER+ HER2− breast cancer; camizestrant; next-generation oral SERD.

Publication types

  • Clinical Trial, Phase I
  • Multicenter Study

MeSH terms

  • Administration, Oral
  • Adult
  • Aged
  • Aged, 80 and over
  • Azetidines
  • Breast Neoplasms* / drug therapy
  • Breast Neoplasms* / genetics
  • Breast Neoplasms* / pathology
  • Dose-Response Relationship, Drug
  • Estrogen Receptor alpha / genetics
  • Female
  • Humans
  • Isoquinolines
  • Maximum Tolerated Dose
  • Middle Aged
  • Receptor, ErbB-2* / antagonists & inhibitors
  • Receptor, ErbB-2* / genetics
  • Receptor, ErbB-2* / metabolism
  • Receptors, Estrogen / metabolism

Substances

  • Receptor, ErbB-2
  • ERBB2 protein, human
  • Receptors, Estrogen
  • Estrogen Receptor alpha
  • ESR1 protein, human
  • AZD9833
  • Azetidines
  • Isoquinolines

Associated data

  • ClinicalTrials.gov/NCT04214288
  • ClinicalTrials.gov/NCT04588298