SABCS 2022: Progression-Free Survival Improved With Camizestrant in Patients With Estrogen Receptor-Positive Breast Cancer
The oral selective ER antagonist and degrader may be superior to fulvestrant
THURSDAY, Dec. 15, 2022 (HealthDay News) – The next-generation oral selective estrogen receptor (ER) antagonist and degrader (SERD) camizestrant improved progression-free survival in women with ER-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer and may be superior to fulvestrant, according to data presented at the San Antonio Breast Cancer Symposium, held from Dec. 6 to 10.
“Despite their significant impact on the management of ER-positive/HER2-negative breast cancer, resistance to existing treatments remains a major obstacle in achieving more durable responses,” Mafalda Oliveira, M.D., Ph.D., of Vall d’Hebron University Hospital and Vall d’Hebron Institute of Oncology in Barcelona, Spain, told Elsevier’s PracticeUpdate. “These tumors commonly acquire a mutation in the ER gene, ESR1, and SERDs such as fulvestrant can block activity in these cases. ESR1-mutated cancers have constitutive activation of the ER and worse prognosis. Seeking out effective treatment options for these patients represents an unmet clinical need.”
Oliveira and colleagues conducted the SERENA-2 trial to evaluate camizestrant versus fulvestrant in patients with ER-positive breast cancer. The study included 240 patients randomly assigned 1:1:1:1 to 75 mg camizestrant, 150 mg camizestrant, 300 mg camizestrant, or fulvestrant. The patients had no prior SERD treatment and one or fewer treatment lines of endocrine therapy and chemotherapy. Patients were stratified according to CDK4/6 inhibitor treatment. The researchers discontinued the 300-mg camizestrant arm early for “strategic reasons,” according to a press release.
Half the patients (49.6 percent) had prior CDK4/6 inhibitor therapy, and at baseline, 36.7 percent had ESR1 mutations and 58.3 percent had lung or liver metastases. The rates of prior chemotherapy and endocrine therapy were 19.2 and 65.4 percent, respectively. The median progression-free survival in the overall population was 7.2 months for camizestrant 75 mg (P = 0.0124), 7.7 months for camizestrant 150 mg (P = 0.0161), and 3.7 months for fulvestrant.
In the ESR1 mutation subgroup, median progression-free survival was 6.3 months in the 75-mg camizestrant group, 9.2 months in the 150-mg camizestrant group, and 2.2 months in the fulvestrant group. In the non-ESR1 mutation group, median progression-free survival was 7.2 months in the 75-mg camizestrant group, 5.8 months in the 150-mg camizestrant group, and 7.2 months in the fulvestrant group.
Grade 3 or higher adverse events occurred in 77, 90.4, and 68.5 percent of the 75-mg camizestrant, 150-mg camizestrant, and fulvestrant groups, respectively. The most common adverse events related to camizestrant were photopsia and sinus bradycardia.
“These positive results and compelling safety profile highlight the potential of this next-generation SERD, support its continued development in treating hormone receptor-positive breast cancer, and could reignite enthusiasm for the development of oral SERDs in breast cancer,” Oliveira told Elsevier’s PracticeUpdate. “Currently there are two phase 3 trials ongoing with camizestrant in the first-line setting, SERENA-4 and SERENA-6, that continue recruitment.”
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