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In certain patients with ESR1-mutant breast cancer, time to next treatment was slightly higher with Orserdu versus PFS in a phase 3 trial.
In patients with hormone receptor (HR)-positive or HER2-negative advanced breast cancer with an ESR1 mutation, Orserdu (elacestrant) showed a similar or slightly higher time to treatment discontinuation and time to the next treatment compared with progression-free survival (PFS) observed in the phase 3 EMERALD trial, according to data from a real-world analysis presented at the 2024 San Antonio Breast Cancer Symposium (SABCS).
Among 742 eligible patients for the outcomes analysis receiving Orserdu (mean age, 63 years), the median real-world time to next treatment (rwTTNT) was 6.43 months and the median real-world time to treatment discontinuation (rwTTD) was 4.6 months.
The EMERALD trial demonstrated improved PFS of 3.8 months vs 1.9 months compared with standard of care endocrine therapy, according to a study published in Clinical Cancer Research.
Progression-free survival (PFS): time during which a patient’s disease does not worsen.
Real-world time to next treatment (rwTTNT): time from starting treatment to starting the next therapy.
Real-world time to treatment discontinuation (rwTTD): time from starting treatment to stopping it for any reason.
Alterations in the PIK3CA pathway: genetic changes affecting cancer growth via the PIK3CA gene.
In addition, most patients received Orserdu beyond the second line of treatment, and the treatment regimen did not significantly impact the outcomes with the drug. Second-line rwTTNT was 8.8 months and 5.3 months for rwTTD. For patients receiving third-line Orserdu, rwTTNT was 5.9 months and rwTTD was 4.5 months. For those receiving fourth-line Orserdu, rwTTNT was 6.4 months and rwTTD was 4.6 months.
Patients with alterations in the PIKA3CA pathway experienced worse outcomes with Orserdu treatment compared with patients without alterations.
Specifically, patients with PI3K pathway alterations experienced a shorter time to next treatment (5.2 versus 8 months), shorter time to treatment discontinuation (four versus 5.3 months) and worse overall survival.
“It's important to note that even though patients received [Orserdu] at fourth line and beyond that, there was no difference in outcomes for those patients,” Dr. Rinath Jeselsohn, Dana-Farber Cancer Institute, said during the poster presentation. “However, patients with alterations with the PIK3CA in the PI3K pathway did have worse outcomes. And this really underscores the need for precision medicine and also for combination treatments in specific patient subgroups.”
Researchers analyzed real-world data from 756 patients with HR-positive or HER2-advanced breast cancer who were treated with Orserdu after FDA approval. The study assessed time to treatment discontinuation and time to next treatment as proxies for PFS, as well as overall survival. Patients on the study were required to have at least 28 days of follow-up following the first Orserdu claim to be included in the outcomes analysis.
The most common sites of metastasis were bone (554 patients), brain (71 patients), liver (237 patients) and lung (115 patients). Most patients had received prior treatment with aromatase inhibitors (683 patients), fulvestrant (402 patients), CDK4/6 inhibitors (624 patients), chemotherapy (312 patients), alpelisib (79 patients), Enhertu (T-DXd; trastuzumab deruxtecan; 58 patients) and Trodelvy (sacituzumab govitecan; 28 patients).
"A real-world analysis of patients with advanced hormone receptor-positive breast cancer with ESR1 mutations identified more than 700 patients treated with [Orserdu] since the approval with very specific criteria,” Jeselsohn concluded. “The time to treatment discontinuation and time to next treatment were overall in the range are slightly higher compared to PFS seen in the EMERALD trial, and most of the patients received [Orserdu] beyond second line of treatment for metastatic disease.”
"Impact of prior treatment, ESR1 mutational (ESR1m) landscape, and co-occurring PI3K pathway status on real-world (RW) elacestrant outcomes in patients (pts) with hormone receptor-positive (HR+)/HER2-negative advanced breast cancer (aBC)" by Dr. Lloyd M, et al., presented at the San Antonio Breast Cancer Symposium (SABCS), PS7-05.
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