Line Endocrine Therapy Research Articles

Camizestrant, a next-generation oral SERD, versus fulvestrant in post-menopausal women with oestrogen receptor-positive, HER2-negative advanced breast cancer (SERENA-2): a multi-dose, open-label, randomised, phase 2 trial

Resistance to endocrine therapies in hormone receptor-positive breast cancer is challenging. We aimed to assess the next-generation oral selective oestrogen receptor degrader (SERD) and complete oestrogen receptor antagonist, camizestrant, versus the first-approved SERD, fulvestrant, in post-menopausal women with oestrogen receptor-positive, HER2-negative, advanced breast cancer. SERENA-2 is an open-label, randomised, phase 2 trial that is being conducted at 74 study centres across Asia, Europe, the Middle East, and North America. Female patients aged 18 years or older who were post-menopausal with histologically or cytologically confirmed metastastic or locoregional oestrogen receptor-positive, HER2-negative breast cancer, an Eastern Cooperative Oncology Group or WHO performance status of 0 or 1, and disease recurrence or progression on at least one line of endocrine therapy, and no more than one previous endocrine therapy in the advanced setting. Patients were initially randomly assigned (1:1:1:1) to receive oral camizestrant once daily at 75 mg, 150 mg, or 300 mg (until the 300 mg group was closed), or fulvestrant intramuscularly at 500 mg (per label). Randomisation was managed through an interactive web-based system and stratified by previous treatment with CDK4/6 inhibitors and presence of liver and/or lung metastases. The primary objective was to determine clinical efficacy of camizestrant versus fulvestrant at each dose level using the primary endpoint of investigator-assessed progression-free survival, per Response Evaluation Criteria in Solid Tumours (version 1.1), assessed by intention to treat in all randomly assigned patients (full analysis set). No formal statistical comparison for the efficacy analysis of the camizestrant 300 mg dose versus fulvestrant was to be performed. Safety analyses included all randomly assigned patients who received at least one dose of study treatment. This study is registered with ClinicalTrials.gov, NCT04214288, and is ongoing. Between May 11, 2020, and Aug 10, 2021, 240 patients were randomly assigned to receive camizestrant 75 mg (n=74), 150 mg (n=73), 300 mg (n=20), or fulvestrant (n=73), and were included in the full analysis set. All patients received at least one dose of study drug. Median follow-up was 16·6 months (IQR 12·9-19·4) for the camizestrant 75 mg group, 16·3 months (12·9-18·3) for the camizestrant 150 mg group, and 14·7 months (12·7-20·1) for the fulvestrant 500 mg group. Median progression-free survival was 7·2 months (90% CI 3·7-10·9) with camizestrant 75 mg, 7·7 months (5·5-12·9) with camizestrant 150 mg, and 3·7 months (2·0-6·0) with fulvestrant. The hazard ratio for camizestrant 75 mg versus fulvestrant was 0·59 (90% CI 0·42-0·82; p=0·017), and the hazard ratio for camizestrant 150 mg versus fulvestrant was 0·64 (0·46-0·89; p=0·0090). Treatment-related adverse events occurred in 39 (53%) of 74 patients in the camizestrant 75 mg group, 49 (67%) of 73 patients in the camizestrant 150 mg group, 14 (70%) of 20 patients in the camizestrant 300 mg group, and 13 (18%) of 73 patients in the fulvestrant group. No single grade 3 or worse treatment-emergent adverse event occurred in more than two (3%) patients in any group. Serious treatment-emergent adverse events occurred in six (8%) patients in the camizestrant 75 mg group, seven (10%) patients in the camizestrant 150 mg group, two (10%) patients in the camizestrant 300 mg group, and four (5%) patients in the fulvestrant group. No treatment-related deaths occurred. Camizestrant at 75 and 150 mg showed a significant benefit in progression-free survival versus fulvestrant. These results support further development of camizestrant for the treatment of oestrogen receptor-positive, HER2-negative breast cancer. AstraZeneca.

Capivasertib and fulvestrant for patients with hormone receptor-positive, HER2-negative advanced breast cancer (CAPItello-291): patient-reported outcomes from a phase 3, randomised, double-blind, placebo-controlled trial

CAPItello-291 is an ongoing phase 3 trial in which capivasertib-fulvestrant significantly improved progression-free survival versus placebo-fulvestrant in patients with hormone receptor-positive, HER2-negative advanced breast cancer who had relapse or disease progression during or after aromatase inhibitor treatment, in both the overall population and in patients with PIK3CA, AKT1, or PTEN-altered tumours. This study further explored patient-reported health-related quality of life (HRQOL), functioning, symptoms, and symptom tolerability in CAPItello-291. This phase 3, randomised, double-blind, placebo-controlled trial, which was conducted across 193 hospitals and cancer centres in 19 countries, enrolled women with any menopausal status or men, aged ≥18 years (≥20 years in Japan), with hormone receptor-positive, HER2-negative locally advanced or metastatic breast cancer who had relapse or disease progression during or after treatment with an aromatase inhibitor, with or without previous cyclin-dependent kinase (CDK) 4 or 6 inhibitor therapy. Patients had an Eastern Cooperative Oncology Group/WHO performance score of 0 or 1 and could have received up to two previous lines of endocrine therapy and up to one previous line of chemotherapy for advanced disease. Patients were randomly assigned (1:1) using block randomisation (stratified according to the presence or absence of liver metastases, previous use of a CDK4/6 inhibitor [yes vs no], and geographical region) to receive oral capivasertib 400 mg (twice daily for 4 days, followed by 3 days off) plus intramuscular fulvestrant 500 mg (every 14 days for the first three injections, then every 28 days) or placebo with matching fulvestrant dosing. The dual primary endpoint of the trial was investigator-assessed progression-free survival assessed both in the overall population and among patients with PIK3CA, AKT1, or PTEN-altered tumours. The EORTC Quality of Life Questionnaire 30-item core module (QLQ-C30) and breast module (QLQ-BR23), Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE), and Patient Global Impression of Treatment Tolerability (PGI-TT) questionnaires were used to assess patient-reported outcomes. Evaluation of EORTC QLQ-C30 and EORTC QLQ-BR23 were secondary endpoints and evaluation of PRO-CTCAE and PGI-TT were pre-defined exploratory endpoints, and these endpoints are the subject of analysis in this Article. Data were collected at baseline and prespecified timepoints. Patient-reported outcomes were analysed in all randomly assigned patients with an evaluable baseline assessment and at least one evaluable post-baseline assessment. Change from baseline was assessed using mixed model with repeated measures for EORTC QLQ-C30 and summarised for QLQ-BR23. Time to deterioration was described using the Kaplan-Meier method. PGI-TT and PRO-CTCAE responses were summarised at each treatment cycle. Patient-reported outcomes were not prospectively powered for statistical comparison. The trial is registered with ClinicalTrials.gov, NCT04305496. Between June 2, 2020, and Oct 13, 2021, 901 patients were enrolled, of whom 708 patients were randomly assigned to receive capivasertib-fulvestrant (n=355) or placebo-fulvestrant (n=353). The median age of the patients was 59 years (IQR 51-67) in the capivasertib-fulvestrant group and 58 years (IQR 49-66) in the placebo-fulvestrant group. At data cutoff (Aug 15, 2022), the median duration of follow-up for progression-free survival in censored patients was 13·0 months (IQR 9·1-16·7) for capivasertib-fulvestrant and 12·7 months (IQR 2·0-16·4) for placebo-fulvestrant in the overall population. EORTC QLQ-C30 global health status/quality of life (GHS/QOL) scores were maintained from baseline and were similar between treatment groups throughout the study period (difference in mean change from baseline of -2·5 [95% CI -4·5 to -0·6] with capivasertib-fulvestrant vs -5·6 [-7·9 to -3·4] with placebo-fulvestrant; treatment difference 3·1 [95% CI 0·2 to 6·0]). Median time to deterioration in EORTC QLQ-C30 GHS/QOL was 24·9 months (95% CI 13·8 to not reached) in the capivasertib-fulvestrant group and 12·0 months (10·2 to 15·7) in the placebo-fulvestrant group (hazard ratio [HR] 0·70, 95% CI 0·53 to 0·92). Time to deterioration HRs for all EORTC QLQ-C30 and QLQ-BR23 subscale scores showed little difference between the treatment groups, except for diarrhoea, which was worse in the capivasertib-fulvestrant group than in the placebo-fulvestrant group (HR 2·75, 95% CI 2·01-3·81). In PRO-CTCAE symptom assessment, the proportion of patients reporting loose and watery stools "frequently" or "almost constantly" was 29% higher at cycle 1, day 15 in the capivasertib-fulvestrant group than in the placebo-fulvestrant group, decreasing at subsequent cycles. Other PRO-CTCAE-reported symptoms (rash, mouth or throat sores, itchy skin, and numbness or tingling in hands or feet) were absent or mild in most patients in both groups throughout treatment. According to the PGI-TT, most patients in both groups reported "not at all" or "a little bit" of bother from treatment side-effects. Patient-reported outcomes from CAPItello-291 demonstrated that capivasertib-fulvestrant delayed time to deterioration of GHS/QOL and maintained other dimensions of HRQOL (except symptoms of diarrhoea) similarly to fulvestrant. With the clinical efficacy and manageable safety profile, these exploratory results further support the positive benefit-risk profile of capivasertib-fulvestrant in this population. AstraZeneca.

First- vs second-line CDK 4/6 inhibitor use for patients with hormone receptor positive, human epidermal growth-factor receptor-2 negative, metastatic breast cancer in the real world setting

PurposeTo compare CDK4/6 inhibitor (CDK4/6i) with endocrine therapy (ET) in the first- versus second-line setting for treatment of hormone receptor positive (HR+), HER2 negative, metastatic breast cancer (MBC) using real-world evidence.MethodsPatients with HR+, HER2 negative MBC, diagnosed between 2/3/2015 and 11/2/2021 and having ≥ 3 months follow-up were identified from the nationwide electronic health record-derived Flatiron Health de-identified database. Treatment cohorts included: (1) first-line ET with a CDK 4/6i (1st-line CDK4/6i) versus (2) first-line ET alone followed by second-line ET with a CDK4/6i (2nd-line CDK4/6i). Differences in baseline characteristics were tested using chi-square tests and two-sample t-tests. Time to third-line therapy, time to start of chemotherapy, and overall survival were compared using Kaplan-Maier method.ResultsThe analysis included 2771 patients (2170 1st-line CDK4/6i and 601 2nd-line CDK4/6i). Patients receiving 1st-line CDK4/6i were younger (75% vs 68% < 75 years old, p = 0.0001), less likely uninsured or not having insurance status documented (10% vs. 13%, p = 0.04), of better performance status (50% vs 43% with ECOG 0, p = 0.03), and more likely to have de novo MBC (36% vs. 24%, p < 0.001). Time to third-line therapy (49 vs 22 months, p < 0.001) and time to chemotherapy (68 vs 41 months, p < 0.001) were longer in those receiving first-line CDK4/6i. Overall survival (54 vs 49 months, p = 0.33) was similar between groups.ConclusionUse of CDK4/6i with first-, vs second-, line ET was associated with longer time to receipt of 3rd-line therapy and longer time to receipt of chemotherapy.

Beyond the median: Estimating survival times for patients starting endocrine therapy for estrogen receptor-positive, metastatic breast cancer from recent randomized trials.

To estimate scenarios for survival for patients with estrogen receptor (ER) positive, metastatic breast cancer (MBC) and to help communicate prognosis to patients starting endocrine therapy (ET) METHODS: We searched for randomized trials of ET for ER-positive MBC and extracted the following percentiles (representative survival scenarios) from each overall survival (OS) curve: 90th (worst-case), 75th (lower-typical), 50th (median), 25th (upper-typical), and 10th (best-case). We then assessed the accuracy of estimating these percentiles for each OS curve by multiplying the median OS by four simple multiples: 0.25 (to estimate the 90th percentile), 0.5 (75th), 2 (25th), and 3 (10th). Estimates were deemed accurate if it fell within 0.75-1.33 times the actual value. We identified 25 trials with 10,566 patients. The median OS (interquartile range) was: 61.3 months (53.4-64.8) for first-line ET with cyclin-dependant kinase 4/6 inhibitors (four treatment groups); 42.6 months (40.9-50.4) for first-line ET alone (21 treatment groups) and 29.2 months (24.8-33.4) for subsequent line ET (19 treatment groups). Simple multiples of the median OS accurately estimated the 90th percentile in 80%; 75th percentile in 93%; and 25th percentile in 76% of curves. The 10th percentile was only available for four OS curves and could not be evaluated. Simple multiples of the median OS are a helpful and accurate method to assist in estimating and discussing scenarios for survival for MBC patients starting ET. Longer follow-up of trials is required to help clinicians estimate the best-case scenario.

Switching from nonsteroidal aromatase inhibitors to exemestane and its impact on menopausal symptoms.

e13098 Background: Aromatase inhibitors (AIs) are the most used adjuvant treatment in post-menopausal women with favorable oncotype, hormone receptor-positive (HR+) early breast cancer. Nonsteroidal AIs, such as anastrozole and letrozole, are associated with menopausal side effects including arthralgias, vaginal dryness, and hot flashes. Steroidal AIs, such as exemestane, however, have mild androgenic activity, thus minimizing the risk for these side effects. While studies show exemestane exhibits less bone toxicity compared to anastrozole, there has not yet been a proven significant difference in all menopausal symptoms. Nevertheless, switching from nonsteroidal to steroidal AI is still commonly seen in clinical practice. In this study, we aimed to examine the impact of switching from nonsteroidal to steroidal AI on menopausal side effects. Methods: We performed a retrospective review of patients diagnosed with HR+ breast cancer managed at an urban academic center from 2010-2023. Patients initially treated with anastrozole or letrozole and switched to exemestane were identified. Pathology records, treatment plans, and documented side effects were abstracted from medical records, as were baseline demographics. Symptoms were graded based on severity before and after each hormone therapy: mild grade described intermittent symptoms that did not require intervention; moderate grade described persistent daily symptoms or those that improved with additional intervention; severe grade described persistent disabling symptoms that required change in hormone therapy. Wilcoxon signed-rank tests were used to compare severity of menopausal symptoms before and after switching to exemestane. Results: There were 128 patients included in the study. Median age at diagnosis was 62.5 years; 13% pre-menopausal, 80% post-menopausal, 4% perimenopausal, and 3% unknown. Most patients were diagnosed with invasive ductal carcinoma (80%) and 45% were found to have stage IA breast cancer. The median amount of time on first and second lines of endocrine therapy were 11 and 25 months, respectively. Ninety-six patients (75%) reported menopausal symptoms on nonsteroidal AI, and 66% subsequently switched to exemestane due to severity of these symptoms. The most reported symptoms were arthralgias (79%), hot flashes (27%), body aches (25%), fatigue (10%), and vaginal dryness (9%). Of those with menopausal symptoms, 51% noted a decrease in symptom severity after switching to exemestane: 4 improved from moderate to mild, 21 from severe to moderate, and 24 from severe to mild. This decrease in severity was statistically significant across all menopausal symptoms (p&lt;0.001). Conclusions: HR+ breast cancer patients exhibited a significant decrease in all menopausal symptoms when switching from nonsteroidal to steroidal AI. Further research is needed to examine the impact of this switch on a wider range of symptoms.

Pulmonary toxicities in patients (pts) with metastatic breast cancer (mBC) treated with trastuzumab deruxtecan (T-DXd): The Mayo Clinic experience.

11145 Background: T-DXd is increasingly used in mBC. A T-DXd toxicity of special interest is interstitial lung disease/pneumonitis (ILD), occurring in 10-15% of pts in the DESTINY-Breast trials, and with potential lower incidence/severity in earlier line settings [Krop et al, ASCO 2023]. However, in routine practice, T-DXd may be used in pts with more heavily pre-treated mBC and previously exposed to other antibody-drug conjugates (ADC) [Premji et al SABCS 2023]. We evaluated the incidence/severity of T-DXd related ILD in mBC at Mayo Clinic. Methods: We retrospectively identified pts with mBC who received ≥1 dose of T-DXd at Mayo Clinic, Rochester, MN, between July 2022-December 2023. Demographic, mBC, and pulmonary clinical variables were abstracted from the clinical records. Data was summarized using descriptive statistics. Diagnosis of ILD was determined by treating clinicians, and severity to CTCAE V5 based on clinical documentation. Results: 77 pts with mBC received T-DXd during the study period. All were female, the majority (70, 91%) were Caucasian, and median age was 58. 53 (69%) had HER2-low mBC (37 HR+, 16 HR-) and 24 (31%) had HER2+ mBC (17 HR+, 7 HR-). 31 (40%) were active or former smokers. 11 (14%) had pulmonary comorbidities, including 6 (7.8%) with asthma, 2 (2.6%) with prior pneumonitis, and 3 (3.9%) with other pulmonary comorbidities. They had previously received a median of 1 line of endocrine therapy, and 4 lines of chemotherapy, with 20 (26%) having received another ADC. 17 (22%) developed any grade ILD [G1: 3 (4%), G2: 7 (9%), G3: 2 (3%), G4: 1 (1%), G5: 4 (5%)]. Among pts with ILD of any grade, 13 (76.5%) presented with at least 1 symptom (cough/SOB). The median number of T-DXd cycles prior to onset of any grade ILD was 6 (range 2-13), or 18 (range 6-39) weeks. 5 (29%) pts with any grade ILD received a prior ADC. Of pts with ≥G3 ILD (n=7), all were Caucasian, 2 (30%) were prior smokers, none had prior lung disease, and had received a median of 5 prior lines of chemo, with 4 (57%) having received a prior ADC. All grade ≥2 ILDs were treated with systemic steroids, and 1 also received IVIG. CT chest was used for diagnosis of all ILD. 7 pts (41%) required hospitalization, all of whom had bronchoscopy, with 5 (29%) requiring intubation. All pts with G1 ILD (3, 18%) restarted T-DXd without ILD recurrence. Conclusions: In this case series,22% of ps treated with T-DXd experienced ILD (5% G5), higher than the rate observed in the pivotal DESTINY-Breast trials, possibly due to real-world use of T-DXd in more heavily pre-treated pts and in pts with pulmonary comorbidities.

Real-world treatment outcomes in patients with HR+ HER2- advanced breast cancer treated with CDK4/6 inhibitors and endocrine therapy.

1067 Background: The addition of cyclin-dependent kinases 4 and 6 inhibitors (CDK4/6i) to endocrine therapy (ET) improves progression-free (PFS) and overall survival (OS) in hormone receptor-positive, HER2-negative advanced breast cancer (HR+/HER2- ABC) in 1st and 2nd line setting. The international guidelines advise using 1st line CDK4/6i; however, its superiority over 2nd line use is debatable. Methods: We retrospectively analyzed clinical data of HR+/HER2- ABC pts administered palbociclib (PAL), ribociclib (RIB) or abemaciclib (ABM) added to either 1st or 2nd line ET. Results: A total of 1511 pts (PAL=507; RIB=724; ABM=280) from 11 cancer Polish centers treated between Sep 2017 and Dec 2023. Median follow-up was 29.6 (95%CI 28.2 to 30.9) months (m). Mean age was 62.6±11.9, 58.9±12.2 and 61.4±10.8 years in PAL, RIB and ABM, respectively. 815 patients (53.9%) had visceral and 1109 (73.4%) bone metastases. 1254 pts (83%) received 1st line CDK4/6i, in 841 (67%) combined with aromatase inhibitor (AI) and in 413 (33%) with fulvestrant (FUL). Second-line CDK4/6i was used in 257 pts (17%); 59 (23%) and 198 (67%) with AI and FUL, respectively. There was no difference in PFS, PFS2, and OS between three CDK4/6i in combination with AIs in 1st and 2nd line setting. Median PFS (95%CI) for 1st line AI with PAL, RIB, ABM were 29.0 (21.6-37.0), 32.0 (24.5-36.9), not reached (N/R) (21.9-N/R) m; PFS2: 37.0 (28.8-N/R), 33.0 (29.5-40.2), N/R (28.9-N/R); OS: 48.9 (42.9-N/R), 48.6 (41.9-N/R), N/R (36.7-N/R). Median PFS (95%CI) for 2nd line AI with PAL, RIB, ABM were 11.9 (9.49-N/R), 10.8 (8.27-N/R), 11.0 (6.43-N/R); PFS2: 22.7 (16.8-N/R), 32.3 (24.9-N/R), 31.0 (13.2-N/R); OS: 27.4 (24.4-N/R), 36.7 (30.1-N/R), 45.5 (29.0-N/R) (no statistical significance). In contrast, RIB+FUL was superior to PAL+FUL and ABM+FUL in both lines (Table). The safety profile was concordant with the reported data for ET + CDK4/6i. Conclusions: Identifying predictive factors of response is essential for the rational use of CDK4/6i and ET in HR+/HER2- ABC. [Table: see text]

HOPE: Harnessing olaparib, palbociclib, and endocrine therapy for BRCA1/2-associated HR+, HER2- metastatic breast cancer.

10616 Background: Thepoly (ADP-ribose) polymerase inhibitor olaparib yields superior progression-free survival, response rates and patient-reported outcomes compared with chemotherapy in patients with BRCA1- or BRCA2- ( BRCA1/2) associated metastatic breast cancer (MBC). Fulvestrant and palbociclib improve outcomes in patients with hormone receptor-positive (HR+) MBC. HOPE (NCT03685331) is a phase I trial to evaluate combination olaparib (O), fulvestrant (F), and palbociclib (P) in patients with BRCA1/2-associated HR+, HER2 negative MBC. Methods: A 3+3 dose escalation was used to assess safety and preliminary efficacy of O, F and P. Eligible participants (pts) had HR+ MBC, a germline (g) or somatic (s) mutation in BRCA1/2, measurable/evaluable disease, any/no prior endocrine therapy, and 0-2 prior lines of chemotherapy for MBC. Prior PARPi and CDK4/6i were permitted but not in combination. Palbociclib was added after a 28-day safety run-in (Cycle 0) of O + F alone. Fulvestrant dose was 500mg IM on day 1 of each 28-day cycle. Dose level 0 (DL0, starting level) was F, O 300mg orally BID continuously, P 75mg orally daily on days 1-21; DL-1 was F, O 250mg orally BID, P 75mg orally daily on days 1-21. The primary endpoint was MTD (adverse events (AEs) based on CTCAE v5.0). Dose limiting toxicity (DLT) period included Cycles 0 and 1. A 30% DLT rate was acceptable; 6 pts had to be treated at a dose for it to be declared MTD. RECIST v1.1 was used to evaluate response. Results: Eight treated pts (s BRCA1:1 ;g BRCA2:6; s BRCA2:1 ) had median (M) age 47; M 0 (0-2) prior lines of endocrine therapy and 0 (0-1) prior chemotherapies for MBC. Three pts each had received O, F, and CDK4/6i as part of their standard of care treatment before study. At DL0, 2/2 pts had DLT with persistent grade(G) 3 neutropenia. Among 6 pts treated at DL-1, none experienced DLT, but 3 pts missed doses of study treatment due to cytopenias (G3 neutropenia, G3 leukopenia, G3 thrombocytopenia) during the DLT period. Following the DLT period, 1 pt reduced O to 200mg orally daily and 1 discontinued P based on provider discretion due to cytopenias (G3 neutropenia, G3 thrombocytopenia). Grade 3 AEs occurring in &gt;1 pt related to study treatment were: neutrophil count decrease (G3/2, n=5/2); white blood cell decrease (G3/2/1, n=3/2/2); platelet count decrease (G3/2/1, n=2/0/1). Overall related AEs in &gt;50% of pts were anemia (n=7), fatigue (n=6) and nausea (n=5). Best responses were CR/PR/SD/PD in 1/1/5/1 pts. Conclusions: MTDof O, F and P (DL-1) was reached and demonstrated antitumor activity. Although no AEs meeting protocol-specified DLT criteria were observed at MTD, hematologic toxicity at this dose complicated drug delivery and required close monitoring during and after the DLT period. Combinations utilizing PARP1 selective inhibitors, lower doses of therapy or sequential rather than combination therapy may improve feasibility. Clinical trial information: NCT03685331 .

Serial analysis of ESR1 and PIK3CA mutations in cell-free DNA from metastatic breast cancer during 1st line endocrine therapy.

e13060 Background: Activating mutations ofESR1 and PIK3CA genes are known mechanisms of endocrine resistance. Recent analysis supported benefit of early intervention at presence of ESR1 mutation in blood (bESR1) before clinical progression. We aimed to investigate ESR1 and PIK3CA mutations detected in cell-free DNA (cfDNA) from patients with hormone receptor-positive, HER2-negative metastatic breast cancer (MBC) and its impact on progression-free survival (PFS). Methods: Thirty patients undergoing 1st line endocrine therapy (ETx) were identified from a prospective cohort. Seven ESR1 hotspot mutations in the ligand binding domain were tested in cfDNA with droplet digital polymerase chain reaction (ddPCR) assay (Genopeaks Co., Ltd). Eleven PIK3CA hotspot mutations were tested using amplicon-targeted sequencing method (Genopeaks Co., Ltd) in both tumor and cfDNA. PFS analyses were performed using Kaplan-Meier methods and compared with the log-rank test. Results: We examined serial cfDNA samples from 26 patients collected every 3-6 months. ESR1 mutations were found in 61.5% (16/26) patients at any timepoint during 1st line endocrine therapy, with D538G being the most common followed by Y537C and 68.8% (11/16) being polyclonal. Among the 50.0% (8/16) bESR1 positive patients with clinical progression, 4 had bESR1 detected before clinical progression while 4 were diagnosed clinical progression concurrently, suggesting the necessity of closer intervals of cfDNA analyses. While presence of bESR1 did not affect PFS overall, 18.8% of patients with bESR1 detected within 6 months after 1st line ETx, displayed worse outcome (median PFS 5 vs 52 months). Also, patients with clearance of bESR1 mutation in subsequent cfDNA (81.3%, 13/16) were shown to have a better outcome (median PFS 52 vs 41 months). Among 14 patients with clinical progression, 8 had bESR1 mutation. Median PFS between patients with bESR1 positive vs negative was 14 vs 9 months. PIK3CA mutations were detected in 69.5% (16/23) of cfDNA at diagnosis of distant metastasis, among them 53.3% (8/15) had co-occurrence with bESR1 mutations. While presence of PIK3CA mutation in primary tumor tissue did not affect disease-free survival nor PFS, patients with blood PIK3CA mutation at diagnosis of metastasis displayed significantly worse outcome (p = 0.041). Conclusions: Substantial number of hormone receptor-positive, HER2-negative MBC patients were detected with ESR1 and PIK3CA mutation in plasma. Though it was a small-sized analysis to accurately assess statistical significance, we observed worse outcome in patients with 1) early detection (&lt;6 months) of bESR1 and with 2) sustained bESR1 during palliative ETx. Patients with clinical progression without bESR1 mutation displayed shorter PFS than patients with bESR1. PIK3CA mutations in cfDNA were prognostic supporting the benefit of combined targeted therapy.

Efficacy analysis of chemotherapy and endocrine therapy combined with targeted drugs after progression on cyclin-dependent kinase 4/6 inhibitor treatment in hormone receptor positive/human epidermal growth factor receptor 2-low metastatic breast cancer

Objective: To evaluate the efficacy of chemotherapy and endocrine therapy combined with targeted drugs after progression on cyclin-dependent kinase 4/6 (CDK4/6) inhibitor treatment in hormone receptor (HR) positive/human epidermal growth factor receptor 2 (HER2)-low metastatic breast cancer. Methods: Patients with metastatic breast cancer diagnosed with HR positive/HER2 low expression at the Fifth Medical Center of PLA General Hospital from October 1, 2018 to September 30, 2023 were retrospectively included. All patients received sequential chemotherapy or sequential endocrine therapy combined with targeted drugs after progression on CDK4/6 inhibitor treatment.The median follow-up was 9 months, and the follow-up ended on October 31, 2023. The patients were divided into chemotherapy group (receiving sequential chemotherapy) and endocrine therapy group (receiving sequential endocrine therapy combined with targeted drugs), according to the treatment plan. Information on demographic data, clinical and pathological diagnosis, treatment regimen, and efficacy evaluation was collected. The basic conditions of patients who may affect the curative effect of different treatment schemes were preset as stratified subgroups, including age, progesterone receptor (PR) status, HER2 status, disease-free survival, number of previous endocrine therapy and chemotherapy, and visceral metastasis. The primary endpoint was progression-free survival (PFS), the secondary endpoints were objective response rate (ORR), clinical benefit rate(CBR) and PFS based on stratification factors. The survival curve was plotted by Kaplan-Meier method, the comparison of PFS between groups was performed by log-rank test, and the comparison of ORR and CBR between groups were performed by χ2 test. Results: A total of 188 patients were included, including 126 patients in the chemotherapy group [all females, aged 29-74 (51±10) years] and 62 patients in the endocrine therapy group [1 male and 61 female, aged 29-77 (51±12) years]. ORR of chemotherapy group was 23.0% (29/126), higher than that of endocrine treatment group [3.2% (2/62)] (P<0.001); The CBR of chemotherapy group and endocrine therapy group were 46.8% (59/126) and 33.9% (21/62), respectively, with no statistical significance (P=0.091). The median PFS of chemotherapy group and endocrine therapy group were 5.0 (95%CI: 4.3-5.7) and 4.0 (95%CI: 1.6-6.4) months, respectively, with no statistical significance (P=0.484). In the preset stratified subgroups, the median PFS of chemotherapy [6.0 (95%CI: 5.4-6.6) months] was longer than that of endocrine combined with targeted therapy [2.0 (95%CI: 1.8-2.2) months] (P<0.001) in PR negative patients; In patients who had progressed on over 2 previous endocrine treatments, the median PFS of chemotherapy [5.0 (95%CI: 3.8-6.2) months] was longer than that of endocrine combined with targeted therapy [2.0 (95%CI: 0.6-3.4) months] (P=0.045). Conclusions: After progression on treatment with CDK4/6 inhibitors for HR-positive/HER2-low expression metastatic breast cancer, both chemotherapy and endocrine therpy combined with targeted drugs are viable treatment options. However, for patients with PR negative or ≥2 lines of endocrine therapy previously, priority should be accorded to chemotherapy.

Abstract PS15-08: Final Overall Survival (OS) analysis of the SAKK 21/12 trial. CR1447 in HR+/HER2- metastatic breast cancer and androgen receptor positive triple negative breast cancer

Abstract Introduction: CR1447 (4-Hydroxytestosteron) is a compound with aromatase inhibitor and anti-androgen receptor activity and is applied transdermally. We assessed its activity and safety in metastatic breast cancer (mBC). The primary endpoint (disease control rate at week 24) was reported in 2019. We now present the final overall survival (OS) analysis of the trial. Methods In cohort A (ER+/HER2-negative metastatic disease), one prior treatment line was allowed and 29 patients (ITT 21 patients) were included. In cohort B (triple negative mBC), eight patients were included. The trial was closed in 2018 due to futility (cohort A) and slow accrual (cohort B). Results At data cut-off on 11.04.2023 92% of all patients had died. Median OS for cohort A was 35.4 months (95% CI: 24.6-49.1) in the ITT population and 19.4 months (95% CI: 2.3-36.8) in the non-ITT population (patients with more than one line of endocrine therapy). In cohort B, median OS was 10.8 months (95% CI: 3.3-28.6). Treatment was well tolerated with no new safety signals and the majority of treatment-related adverse events (TRAE) were Grade 1 and 2. The most common TRAEs were dry skin (43%), rash (16%), fatigue (16%) and nausea (16%). Discussion Despite the trial being negative in terms of the primary endpoint, cohort A (ITT) had a median OS of 35.4 months. There were no new safety signals. Mutational analysis of AR/ER is ongoing to determine benefit of this treatment in specific subgroups. CR1447 might be a candidate drug to combine with other agents (CDK4/6 inhibitors or other targeted therapies). Citation Format: Marcus Vetter, Holer Lisa, Karin Rothgiesser, Wolfgang Schönfeld, Salome Riniker, Roger von Moos, Andreas Torjan, Elena Kralidis, Manuela Rabaglio, Mathias K. Fehr, Andreas Müller, Beat Thürlimann. Final Overall Survival (OS) analysis of the SAKK 21/12 trial. CR1447 in HR+/HER2- metastatic breast cancer and androgen receptor positive triple negative breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS15-08.

Abstract PS17-02: Elacestrant vs standard-of-care in ER+/HER2- advanced or metastatic breast cancer (mBC) with ESR1 mutation: key biomarkers and clinical subgroup analyses from the phase 3 EMERALD trial

Abstract Background: The EMERALD trial reported significantly prolonged progression-free survival (PFS) and a manageable safety profile with elacestrant vs standard of care (SOC) endocrine therapy in patients (pts) with ER+/HER2− ESR1 mutated (ESR1-mut) mBC following progression on prior endocrine therapy (ET). EMERALD is the only pivotal oral SERD clinical trial where prior CDK4/6i usage was mandated. Duration of prior CDK4/6i was shown to be a predictor of efficacy in patients with ESR1 mutations (ESR1-mut) receiving elacestrant, with median PFS (mPFS) for patients with ESR1-mut receiving at least 12 months of CDK4/6i achieved 8.61 months (elacestrant) vs 1.91 months (SOC) (SABCS 2022). This analysis evaluates the clinical benefit of single-agent elacestrant in key clinically relevant subgroups, including biomarkers, usually associated with poorer prognosis. Methods: Patients with ER+/HER2- advanced or mBC who previously had 1-2 lines of endocrine therapy, and prior CDK4/6i, were randomized 1:1 to receive elacestrant or SOC (aromatase inhibitor or fulvestrant). A subgroup analysis was performed on patients with ESR1-mut, by prior duration of CDK4/6i plus ET with at least 12 months in the advanced or metastatic setting, with concomitant presence of liver and/or lung metastases, PIK3CA mutations, TP53 mutation, and HER2 low expression. Results: Overall, 478 patients were randomized to elacestrant (n=239) or SOC (n=239), 228 pts (47.7%) had ESR1-mut, and 159 pts (71.6%) received at least 12 months of prior CDK4/6i. Out of these 159 pts, 113 pts (71%) had liver and/or lung metastases, 62 pts (39%) had a PIK3CA-mut, 61 pts (38%) had TP53m, and 77 pts (48%) had HER2 low expression. A clinically meaningful improvement in PFS favoring elacestrant compared to SOC was consistent across all relevant subgroups in pts with ESR1-mut. Conclusions: Elacestrant showed significantly greater PFS when prior treatment duration with CDK4/6i was at least 12 months, suggesting prior exposure to CDK4/6i is a surrogate marker for endocrine sensitivity. In this population, elacestrant demonstrated superior efficacy, compared to SOC, even in patients with concomitant PIK3CA or TP53 mutations, expression of HER2 low, or presence of liver and/or lung metastases. These results suggest an active ER-driven pathway for this group despite the presence of other resistance mechanisms, where single-agent oral elacestrant could be an attractive option compared to combination therapies or intravenous HER2 low-targeted ADCs. NCT number: NCT03778931 Table. a. Includes E545K, H1047R, E542K amongst others b. HER2 IHC 1+, and 2+ with no ISH amplification Citation Format: Aditya Bardia, Joyce O'Shaughnessy, Francois-Clement Bidard, Patrick Neven, José Ángel García-Sáenz, Philippe Aftimos, Javier Cortés, Janice Lu, Giulia Tonini, Kathy Puvana Theall, Alessandro Paoli, Virginia Kaklamani. Elacestrant vs standard-of-care in ER+/HER2- advanced or metastatic breast cancer (mBC) with ESR1 mutation: key biomarkers and clinical subgroup analyses from the phase 3 EMERALD trial [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS17-02.

Abstract PS15-04: A Phase 1b/2 study of palazestrant (OP-1250), an oral complete estrogen receptor antagonist (CERAN) and selective ER degrader (SERD), with palbociclib in ER-positive, HER2-negative, advanced or metastatic breast cancer patients

Abstract Background: Palazestrant (OP-1250) is a small molecule oral complete estrogen receptor (ER) antagonist (CERAN) and selective ER degrader (SERD) that binds the ligand binding domain of ER and completely blocks ER-driven transcriptional activity in both wild-type (ESR1-wt) and mutant (ESR1-mut) forms of ER. In preclinical studies, palazestrant demonstrated improved tumor growth inhibition and shrinkage when combined with a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor. In a Phase 1/2 monotherapy clinical study in patients with ER-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer, palazestrant was well tolerated with demonstrated antitumor efficacy and favorable pharmacokinetics (PK) supporting once a day (qd) dosing at the recommended Phase 2 dose of 120 mg. In this study, pts received palazestrant at escalating doses of 30, 60, 90, and 120 mg qd in combination with palbociclib (125 mg qd) and no dose-limiting toxicities were observed. Palazestrant did not affect palbociclib PK and no drug–drug interactions (DDIs) occurred. Here we report updates on safety, efficacy, and PK from the ongoing study of palazestrant in combination with palbociclib. Methods: Patients with advanced or metastatic breast cancer with progression on or after ≤1 line of endocrine therapy (prior CDK4/6 inhibitor therapy and ≤1 chemotherapy allowed) were enrolled to receive oral palazestrant 120 mg qd with oral palbociclib 125 mg qd for 21 of 28 days (NCT0526610). Results: As of May 12, 2023, 33 patients have been treated with palazestrant in combination with palbociclib; 12 pts were dosed in the dose-escalation phase and 21 patients were dosed in the dose-expansion phase of the study. Twenty-two patients (67%) received prior CDK4/6 inhibitor therapy; 15 patients received prior palbociclib. Thirteen of 25 patients (52%) with available baseline ctDNA had an ESR1 mutation. The most common (≥20%) treatment-emergent adverse events (TEAEs) were neutropenia, nausea, vomiting, constipation, and diarrhea. Most of these events were grade 1 or 2. The most common grade 3 or 4 related AE was neutropenia (18/33 [55%] were grade 3; 3/33 [9%] were grade 4). The steady-state exposure of palazestrant when dosed with 125 mg palbociclib was consistent with the monotherapy study. Palbociclib exposure at steady-state was comparable to published monotherapy data when combined with palazestrant at all dose levels tested. As of the data cut-off, there were 4 partial responses (2 confirmed) out of 19 response-evaluable patients, with a clinical benefit rate (CBR) of 42% (8/19) across all patients and 67% (6/9) in patients with ESR1 mutations. Conclusions: Palazestrant and palbociclib dosed in combination were well tolerated with a safety profile consistent with the individual profiles of each drug as monotherapy, and there were no DDIs. Tumor responses and clinical benefit were observed in this population of patients, including those who received prior CDK4/6 inhibitors. Expanding on our previous report, these data provide the rationale to continue advancing the clinical development of palazestrant with the approved dose of palbociclib. Updated data will be presented. Citation Format: Arlene Chan, Daphne Day, Phuong Dinh, Michael Slancar, Janine Lombard, Vinod Ganju, Nicole McCarthy, Rosalind Wilson, Demiana Faltaos, Gurpreet Mathauda-Sahota, Caitlin Murphy. A Phase 1b/2 study of palazestrant (OP-1250), an oral complete estrogen receptor antagonist (CERAN) and selective ER degrader (SERD), with palbociclib in ER-positive, HER2-negative, advanced or metastatic breast cancer patients [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS15-04.

Abstract PO3-12-12: Axial Neuropathy in Two Breast Cancer Patients receiving Fam-trastuzumab deruxtecan: A Case Report

Abstract Introduction. Fam-trastuzumab deruxtecan (T-DXd) is FDA approved for metastatic HER2-positive (HER2+) and HER2-low breast cancer (BC). Peripheral neuropathy is a side effect of T-DXd, with an incidence of 13%. Here we discuss two BC patients (pts) who presented with paresthesias of the trunk after receiving T-DXd. Case 1. A 51-year-old female with Stage IIIB cT4N2M0 left BC, estrogen receptor positive (ER+), progesterone receptor positive (PR+) and HER2+ was treated with neoadjuvant docetaxel, carboplatin, trastuzumab, and pertuzumab (TCHP), followed by mastectomy and axillary lymph node dissection, with downstaging to ypT3N2a disease. She was enrolled on a clinical trial comparing T-DXd with standard treatment for HER2+ BC with residual disease after neoadjuvant therapy, and was randomized to T-DXd arm. She also received adjuvant proton radiation therapy to the chest wall. One week after her third cycle of T-DXd she developed Grade 3 paresthesias on her trunk and proximal upper and lower extremities, stating she could not bend over or perform activities of daily living. She did not experience associated weakness or peripheral neuropathy. Symptoms improved to Grade 1 after initiation of gabapentin and delay of cycle 4 T-DXd by one week. She resumed T-DXd with dose reduction per protocol, and increase in gabapentin dose. She was seen by neurology who localized her sensory findings to T5-T9. She was recommended to undergo MRI spine, but was unable to do so, due to presence of tissue expander. Paresthesias have been controlled on dose reduced T-DXd and continued gabapentin. Case 2. A 56-year-old female with ER+, PR+, HER2-negative BC initially diagnosed in 1990, with local recurrence in 2005, treated with mastectomy, adjuvant chemotherapy, and adjuvant endocrine therapy, followed by development of metastatic disease to lung, liver, bone and skin in 2017. She received multiple lines of endocrine therapy, including aromatase inhibitors and fulvestrant, with cdk4/6 inhibitors and everolimus, but either progressed or was intolerant to all treatments. Skin biopsy in 2022 confirmed metastatic BC, which was ER+, PR+, and HER2 low (IHC2+, FISH nonamplified). She then received T-DXd, with clinical and radiographic response to treatment. After cycle 8 T-DXd, the patient was hospitalized for severe burning pain of her trunk and skin. Radiologic evaluation, including CT chest, abdomen, pelvis, and MRI spine, did not show an etiology of her pain, and showed stable metastatic disease to liver and bones, without evidence of cord or nerve root compression. Symptoms improved on pregabalin. She received an additional cycle of T-DXd with dose reduction, but ultimately declined further treatment. Symptoms resolved within 5 months of discontinuation of T-DXd. Discussion. These cases represent unusual events of axial neuropathy in two BC patients receiving T-DXd. Given the similarity of their symptoms, these findings may represent an unusual adverse effect of T-DXd. As the indications for T-DXd continue to expand, clinicians should be aware of this uncommon potential toxicity. Citation Format: Lauren Botero, Katharine McNeill, Della Makower. Axial Neuropathy in Two Breast Cancer Patients receiving Fam-trastuzumab deruxtecan: A Case Report [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-12-12.

Combination of metronomic capecitabine and letrozole in metastatic hormone receptor positive, HER2 negative breast cancer: a randomized phase II trial

First line endocrine therapy is the gold standard for advanced estrogen receptor positive, human epidermal growth factor receptor 2 negative breast cancer. Adding CDK4/6 inhibitors has improved progression free survival. Metronomic Capecitabine has proven to be safe to combine with endocrine therapy with promising efficacy. We conducted a phase II randomized, open label, single centre clinical trial on patients with metastatic ER positive and HER 2 negative breast cancer. Eligible patients were randomized (1:1) to arm A: metronomic dose of capecitabine (500 mg/m2 BID) combined with letrozole (2.5 mg OD) or arm B: letrozole single agent. The primary endpoint was progression free survival. The study was terminated early due to poor accrual and 60 eligible patients out of the planned 204 were randomized. This clinical trial is registered on ClinicalTrials.gov (MD-127-2019, NCT04571437). Between February 2019 and April 2022, 60 patients were randomized. This is the first report of the study, after a median follow-up of 18.6 months. The median age at diagnosis was 47 years with only 41.7% of patients post-menopausal. Half of our patients had bone-only disease, 45% had visceral metastasis (liver and lung) and 63% presented with endocrine sensitive disease. The estimated median PFS for the whole population was 16.2 months. Median PFS for capecitabine arm was 17.7 months versus 14.6 months for letrozole alone (p = 0.078). Overall response rate was 70% for capecitabine/letrozole arm and 56.6% for letrozole only. Clinical benefit rate was 90% in the capecitabine/letrozole arm versus 73.3% in the letrozole arm. Overall survival data is still immature after this short follow up duration. Adverse event assessment showed acceptable all grade and high grade toxicity profile consistent with the established adverse events of both capecitabine and letrozole. Anaemia (28.3%) and hand & foot syndrome (43.8%) were significantly more common in the capecitabine/letrozole arm. Capecitabine combined with letrozole have showed a trend towards improvement in progression free survival with potential more benefit to certain sub-groups and the combination showed acceptable safety profile consistent with the established known safety profile of both letrozole and capecitabine.

Preventing alpelisib-related hyperglycaemia in HR+/HER2−/PIK3CA-mutated advanced breast cancer using metformin (METALLICA): a multicentre, open-label, single-arm, phase 2 trial

Hyperglycaemia is an early and frequent adverse event during alpelisib treatment. METALLICA aimed to evaluate prophylactic metformin to prevent or reduce hyperglycaemia occurrence in patients with HR+/HER2-/PIK3CA-mutated advanced breast cancer (ABC). Between August 13th, 2020 and March 23rd, 2022, this 2-cohort, phase 2, multicentre, single-arm trial (NCT04300790) enrolled patients with HR+/HER2-/PIK3CA-mutated ABC: cohort A, normal glycaemia (fasting plasma glucose <100mg/dL [<5.6mmol/L] and HbA1c <5.7%), and cohort B, prediabetes (fasting plasma glucose 100-140mg/dL [5.6-7.8mmol/L] and/or haemoglobin A1C [HbA1c] 5.7-6.4%). Participants were at least 18 years old, with Eastern Cooperative Oncology Group performance status of 0-1, and up to two prior lines of endocrine therapy (ET) for ABC. Alpelisib plus ET were administered in 28-day cycles after initiation of prophylactic metformin plus ET. Primary endpoint was the incidence of grade 3-4 hyperglycaemia over the first 8 weeks. Secondary endpoints included safety, progression-free survival (PFS), objective response rate (ORR), and clinical benefit rate (CBR). The primary objective for cohort A and B is met with ≤7 (14.6%) and ≤4 (20%) patients with grade 3-4 hyperglycaemia over the first 8 weeks, respectively. 233 patients were screened, and 68 (20.2%) patients were enrolled in cohorts A (n=48) and B (n=20). Median follow-up was 7.8 months (IQR 1.4-19.6). Over the first 8 weeks, one (2.1%) of 48 patients in cohort A (95% CI: 0.5-11.1; P<0.0001), and three (15.0%) of 20 patients in cohort B (95% CI: 5.6-37.8; P=0.016) had grade 3-4 hyperglycaemia. Serious treatment-related adverse events occurred in seven patients (10.3%). The most common were rash (two [2.9%]), vomiting (two [2.9%]), and diarrhoea (two [2.9%]). Discontinuation of alpelisib caused by AEs was reported in nine patients (13.2%), none caused by hyperglycaemia. At data cutoff (15 June, 2022), no treatment-related deaths were observed. In the full analysis set, median PFS was 7.3 months (95% CI: 5.9-not reached), ORR was 20.6% (95% CI: 11.7-32.1%), and CBR was 52.9% (95% CI: 40.4-65.2). In HR+/HER2-/PIK3CA-mutated ABC, prophylactic metformin before alpelisib plus endocrine treatment has low incidence and severity of alpelicib-induced hyperglycaemia. Novartis Pharmaceuticals.

Gedatolisib in combination with palbociclib and endocrine therapy in women with hormone receptor-positive, HER2-negative advanced breast cancer: results from the dose expansion groups of an open-label, phase 1b study

The PI3K-mTOR pathway is frequently dysregulated in breast cancer. Combining an inhibitor targeting all class I PI3K isoforms and mTOR complex 1 (mTORC1)-mTOR complex 2 (mTORC2) with endocrine therapy and a CDK4/6 inhibitor might provide more effective tumour control than standard-of-care therapy. To evaluate this hypothesis, gedatolisib, a pan-PI3K-mTOR inhibitor, was assessed in a phase 1b trial combined with palbociclib and endocrine therapy in patients with hormone receptor-positive, HER2-negative, advanced breast cancer. Results from the dose expansion portion of this trial are reported herein. This multicentre, open-label, phase 1b study recruited female patients aged at least 18 years from 17 sites across the USA with hormone-receptor-positive, HER2-negative, advanced breast cancer and an Eastern Cooperative Oncology Group performance status of 0-1. Four patient groups were studied in the dose expansion portion of the study: treatment-naive in the advanced setting (first line; group A), progression on 1-2 lines of endocrine therapy but CDK4/6 inhibitor-naive (group B); and one or more previous lines (second-line and higher) of therapy, including a CDK4/6 inhibitor (groups C and D). Gedatolisib 180 mg was administered intravenously weekly in 28-day treatment cycles for groups A-C, and on days 1, 8, and 15 for group D. Letrozole (group A), fulvestrant (groups B-D), and palbociclib (all groups) were administered at standard doses and schedules. The primary endpoint was investigator-assessed objective response rate per RECIST version 1.1 in the evaluable analysis set. This trial is completed and registered with ClinicalTrials.gov, NCT02684032. Between Dec 19, 2017, and June 19, 2019, 103 female participants were enrolled in the dose expansion groups A (n=31), B (n=13), C (n=32), and D (n=27). Median follow-up was 16·6 months (IQR 5·7-48·4) for group A, 11·0 months (7·6-16·9) for group B, 3·6 months (1·8-7·5) for group C, and 9·4 months (5·3-16·7) for group D for the primary endpoint. Gedatolisib, palbociclib, and endocrine therapy induced an objective response in 23 (85·2%; 90% CI 69·2-94·8) of 27 evaluable first-line participants (group A). In the second-line and higher setting, an objective response was observed in eight (61·5%; 90% CI 35·5-83·4) of 13 evaluable group B participants, seven (25·0%; 12·4-41·9) of 28 evaluable group C participants, and 15 (55·6%; 38·2-72·0) of 27 evaluable group D participants; this included participants with both wild-type and mutated PIK3CA tumours. The most common grade 3-4 treatment-related adverse events were neutropenia (65 [63%] of 103), stomatitis (28 [27%]), and rash (21 [20%]). Grade 3-4 hyperglycaemia was reported in six (6%) participants. 23 (22%) of 103 participants had a treatment-related serious adverse event, and there were no treatment-related deaths. Nine (9%) participants discontinued treatment because of a treatment-emergent adverse event. Gedatolisib plus palbociclib and endocrine therapy showed a promising objective response rate compared with the published results for standard-of-care therapies and had an acceptable safety profile. Pfizer and Celcuity.

A phase II, multicenter, open-label study of abemaciclib and letrozole in patients with estrogen receptor-positive rare ovarian cancer: ALEPRO trial

BackgroundLow-grade serous and endometrioid ovarian cancers and adult-type granulosa cell tumors are rare ovarian malignancies that show high estrogen receptor positivity. Recurrences of these subtypes of ovarian cancer are often...

First Approval of Elacestrant as a Selective Estrogen Receptor Degrader for the Treatment of Metastatic Breast Cancer.

Elacestrant was approved by the US FDA on January 27, 2023, for treating postmenopausal women or adult men with estrogen receptor (ER)-positive, HER2-negative, ESR1-mutated advanced or metastatic breast cancer with disease progression prior to using at least one line of endocrine therapy. In this short perspective, physicochemical properties, dosage and administration, mechanism of action, pharmacodynamics, pharmacokinetics, drug interaction, and treatment-related adverse reactions of elacestrant are summarized.

Treatment Patterns and Health Outcomes among Patients with HER2 IHC0/-Low Metastatic or Recurrent Breast Cancer

Improved understanding of the biological heterogeneity of breast cancer (BC) has facilitated the development of more effective and personalized approaches to treatment. This study describes real-world evidence on treatment patterns and outcomes for a population-based cohort of patients with human epidermal growth factor receptor (HER2) IHC0 and -low BC with de novo or recurrent disease from Alberta, Canada. Patients 18+ years old diagnosed with HER2 IHC0/-low, de novo/recurrent BC from 2010 to 2019 were identified using Alberta’s cancer registry. Analyses of these patients’ existing electronic medical records and administrative claims data were conducted to examine patient characteristics, treatment patterns, and survival outcomes. A total of 3413 patients were included in the study, of which 72.10% initiated first line hormonal and non-hormonal systemic therapy. The 1-year overall survival (OS) was 81.09% [95% CI, 79.52–82.69]. Recurrent patients had a higher OS compared to de novo patients: 54.30 months [95% CI, 47.80–61.90] vs. 31.5 months [95% CI, 28.40–35.90], respectively. Median OS was 43.4 months [95% CI, 40.70–47.10] and 35.80 months [95% CI, 29.00–41.70] among patients with HER2-low and HER2 IHC0 cancer, respectively. The study results provide real-world evidence regarding the clinical outcomes of HER2 IHC0/-low and de novo/recurrent disease.