SABCS 2022 | SERENA-2: camizestrant vs fulvestrant in post-menopausal women with advanced ER+/HER- breast cancer
Mafalda Oliveira, MD, PhD, Vall d’Hebron Institute of Oncology, Barcelona, Spain, provides an overview of the Phase II SERENA-2 (NCT04214288) trial investigating camizestrant, a next generation oral SERD versus fulvestrant in post-menopausal women with advanced ER-positive HER2-negative breast cancer. The primary objective was to determine clinical efficacy of camizestrant versus fulvestrant by investigator-assessed progression-free survival (PFS). Secondary endpoints included objective response rate (ORR), response duration, clinical benefit rate (CBR) at 24 weeks, overall-survival (OS) and safety. To assess the impact of prior CDK4/6 inhibitor (CDK4/6i) treatment, randomization was stratified so that 50% of patients had prior CDK4/6i. 2/3 of patients had lung or liver metastasis and 20% of patients had prior chemotherapy in the metastatic. 35-40% of patients had a detectable ESR1 mutations at baseline. 75 mg and 150 mg of camizestrant had an improved PFS compared to fulvestrant that was statistically significant and clinically meaningful. Camizestrant was well tolerated.This interview took place at the San Antonio Breast Cancer Symposium (SABCS) 2022 in San Antonio, TX.
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Transcript (edited for clarity)
SERENA-2 is a randomized Phase II study that included patients with ER-positive, HER-2 negative metastatic breast cancer that were postmenopausal and had received and progressed through prior endocrine therapy. Additional inclusion/exclusion criteria included having received at least one prior endocrine therapy or chemotherapy in the metastatic setting and the presence of measurable or evaluable disease...
SERENA-2 is a randomized Phase II study that included patients with ER-positive, HER-2 negative metastatic breast cancer that were postmenopausal and had received and progressed through prior endocrine therapy. Additional inclusion/exclusion criteria included having received at least one prior endocrine therapy or chemotherapy in the metastatic setting and the presence of measurable or evaluable disease.
240 patients were included in the trial, were stratified according to the prior treatment with CDK4/6 inhibitors and the presence of lung or liver disease, and were randomized to received three doses of camizestrant the novel oral selective ER, degrader, 75 milligram, 150 milligram and 300 milligram or the standard of care fulvestrant. The camizestrant 300 milligram dose was discontinued early after 20 patients were included because of strategic reasons, not in the absence of toxicity concerns. So among these 240 patients, half of them had received prior CDK4/6 inhibitors and two-thirds of them had lung or liver metastasis.
20% of them had received prior chemotherapy in the metastatic setting, and importantly, about 35% to 40% of the patients had a detectable ESR-1 mutation at baseline. So the results of SERENA-2 showed that both doses of camizestrant 75 and 150 milligram were superior to fulvestrant in terms of PFS.
The hazard ratio for the 75 comparison was .58 with a median PFS of 7.2 months in the camizestrant 75 milligram arm, compared to 3.7 months in the fulvestrant arm. And the hazard ratio for the 150 comparison was 0.67 with a median PFS of 7.7 months compared to 3.7 months with fulvestrant. These hazard ratios were statistically significant and also clinically meaningful. Importantly in several subgroups of unmet clinical needs, camizestrant at both doses was also superior to fulvestrant. These groups were patients with prior CDK 4/6 inhibitors, patients with lung or liver metastasis, those patients with the presence of ESR-1 mutation at baseline, and also patients with evidence of ER-driven disease. Tolerability of camizestrant was very good. Discontinuations due to adverse events were very infrequent, and so were dose reductions or dose interruptions.
The most common adverse events associated with camizestrant were photopsia, bradycardia that was in almost all cases asymptomatic or grade one, asthenia anemia and althralgia. Again, all these adverse events were mostly grade one, and the rate of grade three or higher adverse events was very rare.
So in conclusion, SERENA-2 is the first trial that demonstrates a superiority of a range of doses of a next-generation oral SERD, camizestrant, over the standard of care, fulvestrant, in patients that are postmenopausal and have ER-positive HER-2 negative breast cancer and with a very tolerable profile. And this results support camizestrant as a next-generation oral SERD to be used in future clinical trials.
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