Eastern Cooperative Oncology Group Research Articles

Prognostic value of skeletal muscle measured by CT at the T4 level in advanced EGFR-positive non-small cell lung cancer patients treated with ecotinib

Objective: To investigate the prognostic value of skeletal muscle measured by CT at the level of the fourth thoracic vertebra (T4) in advanced epidermal growth factor receptor (EGFR)-positive non-small cell lung cancer (NSCLC) patients treated with ecotinib. Methods: The study retrospectively reviewed clinical and pathological characteristics of 176 patients with advanced EGFR-positive NSCLC who received ecotinib and underwent chest CT scans at Wuhan Union Hospital between January 2017 and October 2020. Among them, 70 were male and 106 were female, with ages ranging from 27 to 80 (58.6±10.6) years. As of August 21, 2021, the median follow-up duration was 19.2 months (95%CI: 15.3 to 23.7 months). The optimal cut-off value of skeletal muscle density (T4-SMD) on CT images at the T4 level were determined using X-tile software. Kaplan-Meier analysis and log-rank test were used to plot progression-free survival curves. Cox proportional hazards regression models were employed to analyze factors influencing 1-year progression-free survival (PFS), and a nomogram prognostic model was constructed accordingly. Receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA) were utilized to evaluate the predictive value of the nomogram. Results: The T4-SMD [M (Q1,Q3)] of 176 patients was 42.56 (37.05, 45.93) HU. Patients were divided into low T4-SMD group (n=122) and high T4-SMD group (n=54) based on the cut-off value (The values for males and females were 49.44 and 41.41 HU, respectively) of T4-SMD. The median PFS time and 1-year PFS rate in the low T4-SMD group were significantly lower than those in the high T4-SMD group [10.4 (95%CI: 9.3-11.8) vs 13.7 (95%CI: 11.1-18.5) months, 36.1% vs 59.3%, respectively, P=0.034]. Eastern Cooperative Oncology Group performance status (HR=3.308, 95%CI: 1.183-9.247, P=0.023), lactate dehydrogenase level (HR=1.852, 95%CI: 1.037-3.307, P=0.037), systemic immune-inflammation index (HR=1.772, 95%CI: 1.019-3.080, P=0.043), and T4-SMD (HR=0.563, 95%CI: 0.325-0.974, P=0.040) were prognostic factors for 1-year PFS in advanced EGFR-positive NSCLC patients treated with ecotinib. A nomogram for predicting 1-year PFS of advanced EGFR-positive NSCLC patients treated with ecotinib was constructed based on the four indicators selected by multivariate Cox regression analysis. The area under the ROC curve of the nomogram was 0.775 (95%CI: 0.676-0.874). The calibration curve showed good consistency between the predicted and actual 1-year PFS. DCA demonstrated good clinical prediction effectiveness of the nomogram. Conclusion: Low T4-SMD is a prognostic risk factor for patients with advanced EGFR-positive NSCLC receiving icotinib therapy.

Palliative Surgery for Patients with Gastroesophageal Junction or Gastric Cancer: A Report on Clinical Observational Outcomes.

Few studies have focused on palliative surgery in patients with advanced gastroesophageal junction (GEJ) or gastric cancer. We sought to evaluate clinical observational outcomes following palliative surgery in this population. Patients with GEJ or gastric cancer who underwent palliative surgery (1/2010-11/2022) were identified. The primary outcomes were symptom improvement, ability to tolerate an oral diet, discharge to home, 30 "good days" without hospitalization, and receipt of systemic treatment. Postoperative outcomes and survival were secondarily evaluated. Among 93 patients, the median age was 59 (IQR 47-68) years, and the median Eastern Cooperative Oncology Group Performance Status (ECOG-PS) was 1 (range 0-3). The most frequent indication for palliative surgery was primary tumor obstruction [75 (81%) patients]. The most common procedures were feeding tube placement in 60 (65%) and intestinal bypass in 15 (16%) patients. A total of 75 (81%) patients experienced symptom improvement. Of these, 19 (25%) developed recurrent and 49 (65%) developed new symptoms. ECOG-PS was significantly associated with symptom-free time. Among those who underwent a bypass, resection, or ostomy creation for malignant obstruction, 16 (80%) tolerated an oral diet. Postoperatively, 87 (94%) were discharged home, 72 (77%) had 30 good days, and 64 (69%) received systemic treatment. Postoperative complications occurred in 35 (38%) patients, and 7 (8%) died within 30 days. The median survival time was 7.7 (95% CI 6.4-10.40) months. Patients with incurable GEJ or gastric cancer can benefit from palliative surgery. Prognosis and performance status should inform goals-of-care discussions and patient selection for surgical palliation.

Combination anlotinib and toripalimab for an advanced biliary tract cancer patient with high Eastern Cooperative Oncology Group performance status: a case report.

Up to 80% of biliary tract cancer (BTC) patients relapse within 3 years after surgery and the efficacy of second-line treatment remains dismal for patients who progressed on gemcitabine and cisplatin chemotherapy. Median overall survival of patients with palliative chemotherapy is less than 1 year. The feasibility and safety of targeted therapies plus immunotherapies remain scanty currently, and patients with recurrent or advanced BTCs often experience a rapid decline in Eastern Cooperative Oncology Group (ECOG) performance status. This case report is the first report suggesting a 17-month progression-free survival (PFS), partial response, and another 11-month PFS after progressive disease of anlotinib plus toripalimab in advanced BTC with high ECOG performance status. We report a 67-year-old Chinese male with BTC. He was observed with progressive disease after surgical resection, adjuvant chemotherapy, palliative chemotherapy, and diagnosed with American Joint Committee on Cancer clinical stage IV (cT3N0M1) extrahepatic BTC. The patient experienced a rapid decline in performance status, and he received oral anlotinib and toripalimab with informed consent. MRI scans showed partial response on 22 June 2022. PET-CT showed that tumor activity has been inhibited on 8 March 2023. He achieved 17 months of PFS. Although the patient developed solitary lung metastasis, he had a continuous survival benefit from treatment of anlotinib plus toripalimab after lung radiotherapy. Until the writing of the case draft, he had achieved another 11 months of PFS. The present case suggests that anlotinib plus toripalimab might be a potential effective treatment for advanced BTCs patients with high ECOG performance status.

Anticancer therapy at end-of-life: A retrospective cohort study.

A significant proportion of patients with incurable cancer receive systemic anticancer therapy (SACT) within their last 30 days of life (DOL). The treatment has questionable benefit, nevertheless is considered a quality indicator of end-of-life (EOL) care. This retrospective cohort study aims to investigate the rates and potential predictors of SACT and factors associated with SACT within the last 30 DOL. The study also evaluates the scope of Eastern Cooperative Oncology Group (ECOG) performance status and the modified Glasgow prognostic score (mGPS) as decision-making tools for oncologists. This review of medical records included 383 patients with non-curable cancer who died between July 2018 and December 2019. Descriptive statistics with Chi-squared tests and regression analysis were used to identify factors associated with SACT within the last 30 DOL. Fifty-seven (15%) patients received SACT within the last 30 DOL. SACT within 30 last DOL was associated with shorter time from diagnosis until death (median 234 days vs. 482, p = 0.008) and ECOG score < 3 30 days prior to death (p = 0.001). Patients receiving SACT during the last 30 DOL were more likely to be hospitalised and die in hospital. ECOG and mGPS score were stated at start last line of treatment only in 139 (51%) and 135 (49%) respectively. Those with short time since diagnosis tended to receive SACT more frequently the last 30 DOL. The use of mGPS as a decision-making tool is modest, and there is lack in documentation of performance status.

Outcomes of patients with hepatocellular carcinoma treated with atezolizumab plus bevacizumab in real-world clinical practice who met or did not meet the inclusion criteria for the phase 3 IMbrave150 trial.

Atezolizumab plus bevacizumab (Atezo/Bev) is frequently selected as the primary systemic therapy for hepatocellular carcinoma (HCC). To investigate the outcomes of patients with HCC treated with Atezo/Bev in a real-world setting based on whether they met the inclusion criteria for the phase 3 IMbrave150 trial. A total of 936 patients were enrolled. There were 404 patients who met the inclusion criteria of the phase 3 IMbrave150 trial (IMbrave150 group) and 532 who did not (non-IMbrave150 group). Median progression-free survival (PFS) in the IMbrave150 and non-IMbrave150 groups was 7.4 months and 5.6 months (p = 0.002). Multivariable analysis revealed that non-B, non-C HCC aetiology (hazard ratio [HR], 1.173), α-fetoprotein ≥100 ng/mL (HR, 1.472), Barcelona Clinic Liver Cancer stage ≥ C (HR, 1.318), and modified albumin-bilirubin (mALBI) grade 2b or 3 (HR, 1.476) are independently associated with PFS. Median overall survival (OS) in the IMbrave150 and non-Imbrave150 groups was 26.5 and 18.8 months (p < 0.001). Multivariable analysis revealed that Eastern Cooperative Oncology Group performance status ≥2 (HR, 1.986), α-fetoprotein ≥100 ng/mL (HR, 1.481), and mALBI grade 2b or 3 (HR, 2.037) are independently associated with OS. In subgroup analysis, there were no significant differences in PFS or OS between these groups among patients with mALBI grade 1 or 2a. Patients who are treated with Atezo/Bev and meet the inclusion criteria for the phase 3 IMbrave150 trial, as well as those who do not meet the inclusion criteria but have good liver function, have a good prognosis for survival.

Outcomes and patterns of use of Radium-223 in metastatic castration-resistant prostate cancer

IntroductionRadium-223 dichloride (Ra-223) is recommended as a treatment option for metastatic castration-resistant prostate cancer (mCRPC) patients with symptomatic bone metastases and no visceral disease, after docetaxel failure, or in patients who are not candidates to receive it. In this study, we aimed to ambispectively analyze overall survival (OS) and prognostic features in mCRPC in patients receiving Ra-223 as per clinical routine practice and identify the most suitable treatment sequence.Patients and methodsThis study is observational, multicentric, and ambispective. Eligibility criteria included mCRPC patients treated with Ra-223, with an Eastern Cooperative Oncology Group (ECOG) performance status of 0–2, without visceral metastases, and no more than three cm involved lymph nodes.ResultsA total of 145 patients were included; the median age was 73.97 years, and a Gleason score of more than or equal to 7 in 61 (48%) patients; 73 (81%) had previously received docetaxel. The most important benefit was reached by those patients who received Ra-223 in the second-line setting, with a median OS of 17 months (95% CI, 12–21), and by patients who received six cycles of treatment, with a median OS of 19 months (95% CI, 14–21). An alkaline phosphatase (ALP) decrease was also identified as a prognosis marker. When performing the multivariate analysis, the time to develop castration-resistant disease longer than 24 months was the most important prognostic factor to predict the evolution of the patients receiving Ra-223. Ra-223 was well tolerated, with thrombocytopenia, anemia, and diarrhea being the main adverse events.ConclusionThere is a benefit for those patients who received Ra-223 in the second-line setting, regardless of prior use of docetaxel. In addition, a survival benefit for patients presenting with a decline in ALP was observed.

Phase II study to determine the anti-tumor activity and safety of simlukafusp alfa (FAP-IL2v) combined with atezolizumab in esophageal cancer.

Reported here are results from the esophageal squamous cell carcinoma (SCC) cohort of a Phase II, non-comparative, basket study, evaluating the anti-tumor activity and safety of FAP-IL2v plus atezolizumab in patients with advanced/metastatic solid tumors (NCT03386721). Eligible patients had an Eastern Cooperative Oncology Group performance status of 0-1; measurable metastatic, persistent, or recurrent esophageal SCC; progression on ≥1 prior therapy; and were checkpoint inhibitor naive. Patients received FAP-IL2v 10 mg plus atezolizumab 1200 mg intravenously every 3 weeks, or FAP-IL2v weekly for 4 weeks, then every 2 weeks, plus atezolizumab 840 mg intravenously every 2 weeks. Primary endpoint was investigator-assessed objective response rate (ORR). In the response-evaluable population (N=34), best confirmed ORR was 20.6% (95% confidence interval [CI]: 10.4-36.8) with a complete response (CR) seen in one patient and partial responses (PR) in six patients. Disease control rate was 44.1% (CR=2.9%; PR=17.6%; stable disease [SD]=23.5%) and median duration of response was 10.1 months (95% CI: 5.6-26.7). Median progression-free survival was 1.9 months (95% CI: 1.8-3.7). Analysis of response by PD-L1 expression (Ventana SP263) resulted in an ORR of 26.7 % for patients with PD-L1-positive tumors (tumor area positivity [TAP] cut-off ≥1%; n=15) and 7.1% for patients with PD-L1-negative tumors (TAP cut-off <1%; n=14). Overall, the treatment combination was tolerable and adverse events were consistent with the known safety profiles of each drug. FAP-IL2v plus atezolizumab demonstrated clinical activity and was tolerable in patients with previously treated esophageal SCC.

A phase II randomized, double-blind, placebo-controlled study of Nuvastatic (C50SEW505OESA), a standardized rosmarinic acid-rich polymolecular botanical extract formulation to reduce cancer-related fatigue in patients with solid tumors.

We evaluated the efficacy and safety of Nuvastatic™ (C5OSEW5050ESA)in improving cancer-related fatigue (CRF) among cancer patients. This multicenter randomized double-blind placebo-controlled phase 2 trial included 110 solid malignant tumor patients (stage II-IV) undergoing chemotherapy. They were randomly selected and provided oral Nuvastatic™ 1000mg (N = 56) or placebo (N = 54) thrice daily for 9weeks. The primary outcomes were fatigue (Brief Fatigue Inventory (BFI)) and Visual Analog Scale for Fatigue (VAS-F)) scores measured before and after intervention at baseline and weeks 3, 6, and 9. The secondary outcomes were mean group difference in the vitality subscale of the Medical Outcome Scale Short Form-36 (SF-36) and urinary F2-isoprostane concentration (an oxidative stress biomarker), Eastern Cooperative Oncology Group scores, adverse events, and biochemical and hematologic parameters. Analysis was performed by intention-to-treat (ITT). Primary and secondary outcomes were assessed by two-way repeated-measures analysis of variance (mixed ANOVA). The Nuvastatic™ group exhibited an overall decreased fatigue score compared with the placebo group. Compared with the placebo group, the Nuvastatic™ group significantly reduced BFI-fatigue (BFI fatigue score, F (1.4, 147) = 16.554, p < 0.001, partial η2 = 0.333). The Nuvastatic™ group significantly reduced VAS-F fatigue (F (2, 210) = 9.534, p < 0.001, partial η2 = 0.083), improved quality of life (QoL) (F (1.2, 127.48) = 34.07, p < 0.001, partial η2 = 0.243), and lowered urinary F2-IsoP concentrations (mean difference (95% CI) = 55.57 (24.84, 86.30)), t (55) = 3.624, p < 0.001, Cohen's d (95% CI) = 0.48 (0.20, 0.75)). Reported adverse events were vomiting (0.9%), fever (5.4%), and headache (2.7%). Nuvastatic™ is potentially an effective adjuvant for CRF management in solid tumor patients and worthy of further investigation in larger trials. ClinicalTrial.gov ID: NCT04546607. Study registration date (first submitted): 11-05-2020.

Advanced cutaneous squamous cell carcinoma: Impact of age on the safety and efficacy of cemiplimab and the prognostic significance of blood biomarkers

IntroductionAge-related differences in the safety profile of cemiplimab for patients with locally advanced or metastatic cutaneous squamous cell carcinoma (cSCC) have not been well described.fWe investigated the association of increasing age with immune related adverse events (irAE) from cemiplimab, efficacy outcomes, and the prognostic significance of pre-treatment blood biomarkers in contemporary practice. Materials and MethodsPatients starting first-line cemiplimab for locally advanced or metastatic cSCC at British Columbia Cancer between April 2019 and January 2023 were identified. Landmark four-month logistic regression analysis compared the odds of developing irAE or sequelae amongst patients aged <75 years to those aged 75–84 or ≥ 85. Objective responses were determined using Response Evaluation Criteria in Solid Tumors version 1.1. Univariable Cox proportional hazard (PH) regression modelling of factors associated with overall survival (OS) was performed. ResultsOf 106 patients, the proportions aged <75, 75–84, and ≥ 85 years were 34%, 45%, and 21%, respectively. Overall, the proportion of patients with irAE ≥ grade 3, cemiplimab discontinuation, and hospitalization for immune toxicity was 27.4%, 31.1%, and 11.3%, respectively. There was no clear association between age and the odds of high grade irAE. However, increased odds of cemiplimab discontinuation was observed in patients aged 75–84 years (p = 0.05). Patients ≥85 years had increased hospitalizations due to irAE (OR = 5.00, 95% CI = 0.97–37.52) with two treatment-related deaths. Objective responses were similar across age cohorts (50.0%, 60.4%, and 54.5%) but progressive disease was higher in the age ≥ 85 group (22.2%, 18.8%, and 31.8%). On Cox PH regression analysis, age ≥ 85 years (vs. <75), Eastern Cooperative Oncology Group performance status 2–3 (vs. 0–1), and neutrophil to lymphocyte ratio (NLR) ≥7.80 (vs. <7.80) were associated with shorter survival. DiscussionWhile the odds of high grade irAE were similar across age groups, significant age-related differences in treatment discontinuation and hospitalization due to immune toxicity were observed. Despite a higher incidence of primary progression and shorter OS in the oldest cohort, cemiplimab yielded robust objective responses regardless of age. Higher pre-treatment NLR was associated with shorter survival and the cut-point identified requires further study.

Abstract PO2-05-12: Retrospective analysis on therapeutic efficacy and predictive indicators of eribulin plus anti-angiogenic drugs for metastatic breast cancer

Abstract Background: Eribulin has been widely used for the treatment of metastatic breast cancer (MBC). It has been found that eribulin can work in synergy with Bevacizumab or Anlotinib to achieve anti-angiogenic effects and possible synergistic enhancement. To optimize the efficacy of eribulin usage in late-line MBC patients, it is essential to delve deeper into the effects of combined treatments and gather more real-world clinical outcomes. Therefore, we evaluated the efficacy and safety of eribulin plus the anti-angiogenic drugs in late-line MBC patients. Objective: This study aims to retrospectively analyze the therapeutic efficacy and safety of eribulin plus anti-angiogenic drugs in treating metastatic breast cancer and explore predictive indicators of the therapeutic efficacy of eribulin in treating MBC. Methods: A retrospective review study was performed. 40 Patients diagnosed with MBC and treated with eribulin in Xi’an international medical center hospital from May 2020 to May 2021 were enrolled in this study. Patients were evaluable for this study and divided into two groups based on whether they received eribulin monotherapy or combined therapy. 22 patients were treated with eribulin monotherapy, and 18 were treated with eribulin and anti-angiogenic drugs (Bevacizumab and Anlotinib). Patients’ treatment parameters and characteristics were recorded. The Kaplan-Meier method was used to calculate the median PFS and corresponding 95% confidence interval (CI), and the Cox regression model was used for multivariate analysis of predictive indicators. The Fisher exact probability test was used to compare the difference in adverse reactions between the two groups, with a level of significance set at p-value &amp;lt; 0.05. Results: All study patients have an average of 5 treatment lines and a median progression-free survival (mPFS) of 4.2 months. The eribulin plus anti-angiogenic drug treatment group had a significantly prolonged mPFS compared to the group without anti-angiogenic drug treatment (7.0 months vs 2.0 months, p &amp;lt; 0.001, log-rank). Multivariate analysis identified that the combination of anti-angiogenic therapy (HR = 0.043, p = 0.004) and the occurrence of grade 3-4 neutropenia after treatment were two predictive factors for longer PFS (HR = 0.322, p = 0.009). In contrast, prior resistance to taxanes was predictive of shorter PFS (HR = 4.583, p = 0.019). Other factors, including age, Eastern Cooperative Oncology Group (ECOG) performance status, hormone receptor (HR) type, expression status, human epidermal growth factor receptor-2 (HER-2) expression status, Ki-67 level, number of metastatic lesions, and number of prior lines of Eribulin therapy, were not significantly associated with PFS. The results of Fisher’s exact test show that there was no significant increase in treatment-related adverse events (all grades) after combination with anti-angiogenic drugs. Conclusion: A combination of eribulin and anti-angiogenic therapy has significantly prolonged mPFS in the treatment of MBC patients. Other factors such as prior non-taxane resistance, grade 3-4 neutropenia occurrence after treatment, and combined anti-angiogenic therapy can be used as biomarkers for predicting treatment efficacy. The adverse events are manageable and the safety of combined therapy can be guaranteed. Therefore, the eribulin plus anti-angiogenic combination may act as a potential therapy for late-line MBC patients with clinically beneficial therapeutic effects. Keywords: metastatic breast cancer, eribulin, anti-angiogenic therapy, retrospective analysis Citation Format: Junmei Zhang, Xuezheng Wang, Hongjuan Du, Yan Xue. Retrospective analysis on therapeutic efficacy and predictive indicators of eribulin plus anti-angiogenic drugs for metastatic 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 PO2-05-12.

Impact of an Inter-Professional Clinic on Pancreatic Cancer Outcomes: A Retrospective Cohort Study

Background: Pancreatic ductal adenocarcinoma (PDAC) presents significant challenges in diagnosis, staging, and appropriate treatment. Furthermore, patients with PDAC often experience complex symptomatology and psychosocial implications that require multi-disciplinary and inter-professional supportive care management from health professionals. Despite these hurdles, the implementation of inter-professional clinic approaches showed promise in enhancing clinical outcomes. To assess the effectiveness of such an approach, we examined the impact of the Wallace McCain Centre for Pancreatic Cancer (WMCPC), an inter-professional clinic for patients with PDAC at the Princess Margaret Cancer Centre (PM). Methods: This retrospective cohort study included all patients diagnosed with PDAC who were seen at the PM before (July 2012–June 2014) and after (July 2014–June 2016) the establishment of the WMCPC. Standard therapies such as surgery, chemotherapy, and radiation therapy remained consistent across both time periods. The cohorts were compared in terms of survival rates, disease stage, referral patterns, time to treatment, symptoms, and the proportion of patients assessed and supported by nursing and allied health professionals. Results: A total of 993 patients were included in the review, comprising 482 patients pre-WMCPC and 511 patients post-WMCPC. In the multivariate analysis, adjusting for ECOG (Eastern Cooperative Oncology Group) and stage, it was found that post-WMCPC patients experienced longer median overall survival (mOS, HR 0.84, 95% CI 0.72–0.98, p = 0.023). Furthermore, the time from referral to initial consultation date decreased significantly from 13.4 to 8.8 days in the post-WMCPC cohort (p &lt; 0.001), along with a reduction in the time from the first clinic appointment to biopsy (14 vs. 8 days, p = 0.022). Additionally, patient-reported well-being scores showed improvement in the post-WMCPC cohort (p = 0.02), and these patients were more frequently attended to by nursing and allied health professionals (p &lt; 0.001). Conclusions: The implementation of an inter-professional clinic for patients diagnosed with PDAC led to improvements in overall survival, patient-reported well-being, time to initial assessment visit and pathological diagnosis, and symptom management. These findings advocate for the adoption of an inter-professional clinic model in the treatment of patients with PDAC.

Abstract PO1-19-04: Dalpiciclib and tucidinostat in patients with HR+/HER2- advanced breast cancer and resistance to CDK4/6 inhibitors: A phase Ib trial

Abstract Background: Hormone receptor (HR)-positive/epidermal growth factor receptor 2 (HER2)-negative breast cancer accounts for approximately 70% of all breast cancers and is associated with a better prognosis. Estrogen plays an important role in the growth of HR-positive breast cancer, thus patients with this type of tumor are sensitive to hormone inhibitors. However, a quarter of patients will inevitably relapse. Several large clinical trials have demonstrated that the combination of CDK4/6 inhibitors and endocrine therapy (ET) as first or second-line therapy could improve the progression-free survival (PFS) and overall survival for patients with breast cancer. In China, dalpiciclib (a CDK4/6 inhibitor) in combination with fulvestrant has been approved for patients with recurrent or metastatic HR-positive/HER2-negative breast cancer who have failed ET. Moreover, the combination of dalpiciclib and aromatase inhibitors (AI) as an initial treatment for patients with locally advanced or metastatic HR-positive/HER2-negative breast cancer has also been accepted. However, the standard treatment for patients who have failed CDK4/6 inhibitors has not been established. Histone deacetylase (HDAC) inhibitors cause alterations in gene expression in many signaling pathways associated with oncogenesis, leading to the arrest of tumor cell growth and differentiation, as well as promoting tumor apoptosis. Tucidinostat (an HDAC inhibitor) plus AI has been approved for the treatment of locally advanced HR-positive/HER2-negative postmenopausal breast cancer patients who have failed ET. Theoretically, synergistic effects may occur when HDAC inhibitors are combined with CDK4/6 inhibitors. Currently, the clinical data on combination therapy with CDK4/6 inhibitors and HDAC inhibitors have not been reported. Herein, our study aims to explore the efficacy and safety of dalpiciclib and tucidinostat in patients with late-stage HR+/HER2- breast cancer who have failed CDK4/6 inhibitors. Trial Design: The present study is a single-arm, open-label, phase I, dose escalation clinical trial (NCT 05586841). Patients were assigned to four groups to receive either dalpiciclib 125mg/d and tucidinostat 25mg/BIW (group A) or dalpiciclib 125mg/d and tucidinostat 20mg/BIW (group B) or dalpiciclib 100 mg/d and tucidinostat 25mg/BIW (group C) or dalpiciclib 100 mg/d and tucidinostat 20mg/BIW (group D). The Bayesian Optimal Interval (BOIN) design was performed to determine dose-escalation and de-escalation to find the maximum tolerated dose (MTD) of dalpiciclib plus tucidinostat. Key Eligibility Criteria: The study is enrolling female patients who are older than 18 years, with HR-positive/HER2-negative locally recurrent or metastatic breast cancer (MBC), with Eastern Cooperative Oncology Group (ECOG) performance status score of 0 to 2. Before entering this trial, all patients must have received ≤1 previous line of chemotherapy for recurrent or MBC, and have failed CDK4/6 inhibitor therapy. Aims: The BOIN design is employed to explore the optimal dose combination of dalpiciclib and tucidinostat and determine recommended doses for a phase II dose expansion clinical trial, based on prespecified dose-limiting toxicity (DLT). Statistical Methods: Safety will be evaluated in the safety set including all patients who received at least one dose of study treatment and underwent at least one safety assessment. Efficacy will be assessed in the full analysis set, defined as all patients who received at least one dose of study treatment. Present and Planned Accrual: Up to 30 participants were planned to be enrolled in the present study. The first participant was enrolled on 18 January 2023. The recruitment is ongoing. Citation Format: Tao Wang, Jinmei Zhou, Xuexue Wu, Zefei Jiang. Dalpiciclib and tucidinostat in patients with HR+/HER2- advanced breast cancer and resistance to CDK4/6 inhibitors: A phase Ib 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 PO1-19-04.

Abstract PO3-17-07: Real-world experience with trastuzumab deruxtecan in patients with breast cancer: 6 month-interim analysis of an all-patient postmarketing surveillance in Japan

Abstract Background: Trastuzumab deruxtecan (T-DXd) is an anti-human epidermal growth factor receptor 2 (HER2) antibody-drug conjugate. T-DXd has shown great efficacy in HER2-positive breast cancer, hence receiving approval in Japan in March 2020. In Japan, all-patient postmarketing surveillance (PMS) is underway to evaluate the risk of interstitial lung disease/pneumonitis (ILD/p) in patients with breast cancer treated with T-DXd. Due to the limited generalizability of results from clinical trials, there is a need for more information about ILD/p in a real-world setting. Herein we present an interim analysis of the large-scale all-patient PMS. Methods: This is an observational, multicenter, all-patient PMS (jRCT1080225197) with an observation period of 18 months that enrolled all patients treated with T-DXd for recurrent/advanced HER2-positive breast cancer. Patients who initiated T-DXd treatment between May 2020 (launch date of T-DXd) and May 2021 were included in the interim analysis to ensure the observation period of 6 months from the initial treatment of T-DXd. This interim analysis is based on safety data from the first 6 months of 1204 patients. Data collected includes baseline characteristics and information on ILD/p. All potential ILD/p (identified based on the AE terms) reported by physicians were adjudicated by an independent ILD adjudication committee. The incidence of ILD/p was calculated from adjudicated drug-related ILD/p. Results: The interim analysis set included 1204 patients with median age of 60 years. Three of the 1204 patients (0.2%) received T-DXd as a first-line treatment, 30 (2.5%) as second-line, 1159 (96.3%) as third- line or later treatment. At baseline, 105 (8.7%) of patients had an Eastern Cooperative Oncology Group performance status (ECOG PS) 2 or greater, 8 (0.7%) had severe renal impairment (15≤ creatinine clearance (CLcr) &amp;lt; 30 mL/min), 4 (0.3%) had end-stage renal disease (CLcr &amp;lt; 15 mL/min), 5 (0.4%) had severe liver impairment (total bilirubin &amp;gt;4.5 mg/dL), and 32 (2.7%) had comorbid ILD/radiation pneumonitis. Those were defined as exclusion criteria in clinical trials of T-DXd. The median dose at the start of administration of T-DXd was 5.4 mg/kg (range:2.7-5.4). During the first 6 months from the initial treatment, T-DXd was discontinued in 403 (33.5%) of the 1204 patients. The most common reasons for discontinuation were disease progression in 232 (57.6%) of the discontinued 403 patients followed by ILD/p in 97 (24.1%) of the 403 patients. In the first 6 months, the incidence of all grade, grade ≥3, and grade 5 ILD/p were 8.2% (n=99), 1.7% (n=20) and 0.4% (n=5), respectively. The incidence of ILD/p stratified by baseline characteristics identified as potential risk factors of drug-related ILD/p is shown in Table. Conclusion: This is the first report demonstrating real-world experience with T-DXd in Japan. The interim analysis revealed useful information including patient and treatment profiles of T-DXd and the incidence of ILD/p during the first 6 months from the initial treatment in a real-world setting in Japan. The final analysis of the ongoing PMS is warranted for further evaluation. Incidence of interstitial lung disease/pneumonitis by patient baseline characteristics XX XX ILD/p: interstitial lung disease/pneumonitis, 95% CI: 95% confidence interval, CLCr: creatinine clearance using the Cockcroft-Gault equation * includes ILD/p, pulmonary fibrosis, radiation pneumonitis, chronic obstructive pulmonary disease, emphysema, and Asthma (Source: Powell CA, Modi S, Iwata H, et al. Pooled analysis of drug-related interstitial lung disease and/or pneumonitis in nine trastuzumab deruxtecan monotherapy studies. ESMO Open 2022;7(4):100554) Citation Format: Junji Tsurutani, Hideki Mizutani, Ayumi Tanabe. Real-world experience with trastuzumab deruxtecan in patients with breast cancer: 6 month-interim analysis of an all-patient postmarketing surveillance in Japan [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 PO3-17-07.

Abstract PO1-06-03: Efficacy of First-line Treatments for Hormone Receptor-positive, Human Epidermal Growth Factor Receptor 2-positive Metastatic Breast Cancer: A Systematic Literature Review and Network Meta-analysis Feasibility Assessment

Abstract Background: A comprehensive summary of clinical evidence for first-line (1L) treatments for hormone receptor-positive, human epidermal growth factor receptor 2-positive (HR+/HER2+) advanced or metastatic breast cancer (mBC) is needed to understand which treatments have been evaluated and the outcomes associated with different treatments. Understanding the available clinical evidence for HR+/HER2+ mBC 1L treatments can also inform the feasibility of network meta-analyses (NMAs) to estimate relative treatment effects where head-to-head trials are not available. The objective was to prepare a systematic summary of clinical trials of 1L treatments for HR+/HER2+ mBC and assess the feasibility of NMAs for key efficacy outcomes. Methods: A systematic literature review (SLR) was conducted per Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Clinical trials evaluating 1L treatments for adults with HR+/HER2+ mBC published between January 2000 and January 2023 were identified via predefined searches of databases (Embase, MEDLINE, Cochrane Library), relevant congress proceedings, and ClinicalTrials.gov (updating a previous SLR covering January 2000 to December 2020). Study design characteristics, patient characteristics, and efficacy outcomes were extracted from identified trials. An NMA feasibility assessment that considered network connectivity and cross-study heterogeneity was conducted for four efficacy outcomes of interest: progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and clinical benefit rate (CBR). Results: After screening, 37 records reporting on 23 unique studies (11 randomized controlled trials [RCTs] and 12 single-arm trials; 35 study arms in total) were selected. Included trials were mostly phase II or phase III multi-country studies that evaluated a HR+ or HER2+ population, with outcomes being reported for the subgroup of patients with the HR+/HER2+ subtype. Treatments evaluated included one or two anti-HER2 therapies (AHTs) + endocrine therapy (ET) (5/35 study arms), AHTs + chemotherapy (CT) (20/35), AHTs + ET + CT (2/35), AHTs alone (5/35), and ET alone (3/35). For HR+/HER2+ patients, PFS and OS were reported by 17/23 and 10/23 studies, respectively. Reported median PFS and OS ranged from 2.4-23.7 months and 23.9-66.7 months, respectively. Among the 11 included RCTs, hazard ratios and/or Kaplan-Meier curves, which were considered a requirement for NMAs for time to event outcomes, were reported for PFS and OS by 9 and 6 studies, respectively. Among these studies, reported median PFS and OS ranged from 2.4-19.2 months and 23.9-57.9 months, respectively. For HR+/HER2+ patients, ORR and CBR were reported by 13/23 and 6/23 studies, respectively. Assuming all CTs could be considered equivalent treatments and all ETs could be considered equivalent treatments, NMAs involving networks of 9, 6, 6, and 3 treatments were feasible for PFS, OS, ORR, and CBR, respectively. Some patient characteristics including time since mBC diagnosis and proportion with bone metastases were not reported consistently across trials. However, included studies were broadly comparable based on study design characteristics, outcome definitions and other reported patient characteristics such as age and Eastern Cooperative Oncology Group performance status. Conclusion: Clinical trials in 1L HR+/HER2+ mBC have evaluated various combinations of AHTs, CTs, and ETs, with most study arms being AHTs + CT. Although efficacy outcomes of interest were not consistently reported across trials, NMAs were found to be feasible for PFS, OS, ORR, and CBR based on available data. Citation Format: Priyanka Sharma, Chau Dang, Christopher Drudge, Amrita Debnath, Manvir Rai, Eric Gauthier, Edward Broughton. Efficacy of First-line Treatments for Hormone Receptor-positive, Human Epidermal Growth Factor Receptor 2-positive Metastatic Breast Cancer: A Systematic Literature Review and Network Meta-analysis Feasibility Assessment [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 PO1-06-03.

Abstract PO3-18-09: OPERA-01: A randomized, open-label, phase 3, study of palazestrant (OP-1250) vs standard-of-care treatment for ER+, HER2- advanced or metastatic breast cancer after endocrine and CDK4/6 inhibitor therapy

Abstract Background: In estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (MBC), adding a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor to endocrine therapy (ET) has improved outcomes and is the current standard-of-care treatment in the first-line setting. However, resistance to first-line treatment develops in most patients (pts), which is often attributed to acquired mutations in ESR1. Limited data exist for ET-based treatment options after progression on prior ET and CDK4/6 inhibitors, and most pts will transition to chemotherapy for further treatment. Therefore, there is a significant unmet need for more effective ET in pts with ER-positive, HER2-negative MBC to improve outcomes and delay time to chemotherapy. Palazestrant (OP-1250) is a small molecule oral complete 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 better tumor shrinkage in ESR1-wt and ESR1-mut models when compared to fulvestrant; it also showed efficacy in brain metastasis models. In a phase 1/2 monotherapy study in pts with heavily pretreated ER-positive, HER2-negative advanced breast cancer (BC) or MBC (NCT04505826), palazestrant showed a tolerable safety profile, promising antitumor efficacy, and favorable pharmacokinetics (PK) supporting once a day (qd) dosing. The recommended Phase 2 dose of palazestrant is 120 mg qd. Methods: The OPERA-01 trial is an international, multicenter, randomized, open-label, phase 3 clinical trial comparing the efficacy and safety of palazestrant as a single agent to standard-of-care ET (fulvestrant, anastrozole, letrozole, or exemestane) in pts with ER-positive, HER2-negative advanced BC or MBC that has relapsed or progressed on 1 or 2 prior lines of ET for MBC, which includes a CDK4/6 inhibitor. Eligible pts are women (pre- or post-menopausal) or men who have a confirmed diagnosis of ER-positive, HER2-negative locally advanced evaluable BC or MBC not amenable to curative therapy. ER and HER2 status are determined according to the American Society of Clinical Oncology/College of American Pathologists guidelines. Patients must have Eastern Cooperative Oncology Group performance status 0 or 1. Prior treatments must include 1 or 2 prior lines of ET as monotherapy or in combination with a CDK4/6 inhibitor for MBC; must have received CDK4/6 inhibitor in combination with ET and have disease progression during or within 28 days of completion of each line of prior treatment for MBC; most recent ET given for ≥6 months. Prior chemotherapy in the metastatic setting is not permitted. Patients (N∼500) are randomized to palazestrant or standard-of-care ET monotherapy, and are stratified by ESR1 mutation status, prior lines of ET for advanced disease (1 vs 2 lines), and presence or absence of visceral disease. The primary endpoint of progression-free survival will be assessed by blinded independent central review in pts with and without ESR1 mutations in the intent-to-treat population. Secondary endpoints include overall survival, antitumor activity (objective response rate, clinical benefit rate, and duration of response), safety, patient-reported outcomes, and PK in pts with and without ESR1 mutations. The study is planned to be conducted globally. Citation Format: Arlene Chan, Jane Meisel, Komal Jhaveri, Joo Hyuk Sohn, Meritxell Bellet- Ezquerra, Jason Schroeder, Mark Shilkrut, Barbara Pistilli. OPERA-01: A randomized, open-label, phase 3, study of palazestrant (OP-1250) vs standard-of-care treatment for ER+, HER2- advanced or metastatic breast cancer after endocrine and CDK4/6 inhibitor therapy [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 PO3-18-09.

Abstract PO3-27-12: Dexamethasone is necessary for preventing acute emesis induced by anthracycline/cyclophosphamide chemotherapy (HELEN-009) : a multicenter, randomized, open-labeled phase 3 trial

Abstract Background Olanzapine, in combination with NK1 receptor antagonist (RA), 5-hydroxytryptamine-3 (5-HT3) RA, and dexamethasone, is now the standard approach to prevent chemotherapy-induced nausea and vomiting (CINV). In this study, we assessed the preventive effect of removing dexamethasone from the quadruple standard antiemetic regimen on CINV caused by anthracycline/cyclophosphamide chemotherapy. Methods The HELEN-009 was a multicenter, randomized, open-labeled phase 3 trial to evaluate the efficacy of NK1RA,5-HT3RA and Olanzapine triplet-combination antiemetic therapy done in 3 hospitals in China.Key inclusion criteria were patients with early breast cancer who were scheduled to be treated with epirubicin plus cyclophosphamide chemotherapy for the first time, age between 18 and 75 years, and with Eastern Cooperative Oncology Group performance status of 0–1. Eligible patients were randomly assigned (1:1) to receive either fosaprepitant, tropisetron, dexamethasone and olanzapine(quadruple group)or fosaprepitant, tropisetron and olanzapine without dexamethasone(triple group). Patients were randomly assigned to interventions by use of a web entry system and the minimization method with a random component, with age as factors of allocation adjustment. The primary endpoint was the proportion of patients who achieved a complete response, defined as absence of vomiting and no use of rescue medications in the overall phase (days 1–5) after starting chemotherapy. All randomly assigned patients who satisfied eligibility criteria received epirubicin plus cyclophosphamide chemotherapy were included in efficacy analysis. All patients who received any treatment in this study were assessed for safety. This study is registered at Clinical Trials Registry, number NCT05242874. Findings Between January 2022 and July 2023, 439 patients with breast cancer were enrolled in the study, with 218 participants randomly assigned to quadruple group and 221 participants assigned to triple group. All eligible patients were observed 120 h after epirubicin plus cyclophosphamide chemotherapy initiation. One patient in the quadruple group withdrew consent. One patient in the quadruple group and one in triple group discontinued treatment on day 1 and was excluded from the efficacy analysis. In the overall phase, the proportion of patients who achieved a complete response was 180 (83.3% [95% CI 78.3–88.3] of 216 patients in the quadruple group and 137 (62.4% [55.8–68.7] of 220 patients in the triple group (p&amp;lt; 0·0001). No grade 3 or higher treatment-related adverse events occurred in either of the groups. Interpretation Dexamethasone remains essential in preventing acute emesis in patients receiving epirubicin plus cyclophosphamide chemotherapy. Table. Proportion of patients in the efficacy analysis set achieving a complete response Table. Treatment-related adverse events with an incidence ≥ 2% Citation Format: Xiuchun Chen, Jiao Dechuang, Chongjian Zhang, Xianfu Sun, Zhenduo Lu, Lianfang Li, Jianghua Qiao, Chengzheng Wang, Min Yan, Yueqing Feng, Ya Wei, Zhenzhen Liu. Dexamethasone is necessary for preventing acute emesis induced by anthracycline/cyclophosphamide chemotherapy (HELEN-009) : a multicenter, randomized, open-labeled phase 3 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 PO3-27-12.

Abstract PO1-28-07: Neoadjuvant docetaxel plus cisplatin versus docetaxel plus doxorubicin and cyclophosphamide in early-stage triple-negative breast cancer (HNBC-001): results from a multicenter, randomized controlled, open-label phase II trial

Abstract Background: Adding platinum to anthracycline- and taxane-based neoadjuvant chemotherapy has improved pathological complete response (pCR) in patients with triple-negative breast cancer (TNBC). However, the efficacy of combining docetaxel and platinum without anthracycline remains controversial. Methods: The HNBC-001 trial was a randomized, phase 2 controlled, and open-label investigation carried out in China at 6 hospitals. The participants who were aged 18–70 years, were histologically confirmed for TNBC clinical stage II–III, suitable for potentially curative surgery, and had an Eastern Cooperative Oncology Group performance status (ECOG-PS) of 0 or 1 were selected for this trial. Participants were randomly categorized into two equal groups; those who received docetaxel plus cisplatin (75 mg/m2, respectively) and those who received docetaxel plus doxorubicin and cyclophosphamide (docetaxel 75 mg/m2, doxorubicin 50 mg/m2, and cyclophosphamide 500 mg/m2). These regimens were given every 3 weeks for 6 cycles. Randomization was stratified by tumor size and nodal status. The primary endpoint was the number of individuals achieving a pCR (ypT0/is ypN0). The trial was registered with chictr.org (number ChiCTR-1800019501). Results: Between November 28, 2018, and June 11, 2022, 212 patients were selected (n=106/treatment). The number of individuals who achieved pCR after docetaxel plus cisplatin treatment was 51.9%, and that of those who attained pCR after docetaxel plus doxorubicin and cyclophosphamide was 35.8% (P=0.019). After 21 months of median follow-up [interquartile range (IQR), 13 to 33], 11 of 106 patients (10.4%) in the docetaxel plus cisplatin group and 14 of 106 patients (13.2%) in the docetaxel plus doxorubicin and cyclophosphamide group had event-free survival (EFS) events [95% confidence interval (CI) =0.360 to 1.783, hazard ratio (HR) =0.801, P=0.585]. The incidence of grade 3 or 4 events was similar in both groups [57 (54%) vs. 51 (48%)]. However, no treatment-associated deaths were identified. Conclusions: In stage II to III TNBC, the docetaxel plus cisplatin regimen achieved higher pCR rates than docetaxel plus doxorubicin and cyclophosphamide, with a manageable toxicity profile. Consistent with the literature, the docetaxel plus cisplatin regimen demonstrated a favorable risk-to-benefit profile and could serve as an optimal neoadjuvant chemotherapy option for patients with high-risk TNBC. table 1: Patient characteristics figure 1: Study endpoints Error bars denote 95% CIs based on normal approximation. p values were calculated from the Chi-square test. (A) Frequency of patients who achieved a pathological complete response per treatment group (primary endpoint). (B) Frequency of patients who achieved a clinical breast tumour response per treatment group, assessed by serial MRI scans after completion of neoadjuvant treatment. (C) Frequency of patients who achieved a minimal residual disease (residual cancer burden class 0 or 1). (D) Frequency of patients who received breast-conservation surgery. table 2: Treatment-emergent adverse events Citation Format: Dechuang Jiao, Jianghua Qiao, Chengzheng Wang, Juntao Li, Xianfu Sun, Zhenduo Lu, Chongjian Zhang, Lianfang Li, Min Yan, Yueqing Feng, Yong Zhou, Miao Deng, Xinlan Liu, Mingde Ma, Haiquan Jia, Qingxin Xia, Xiuchun Chen, Zhenzhen Liu. Neoadjuvant docetaxel plus cisplatin versus docetaxel plus doxorubicin and cyclophosphamide in early-stage triple-negative breast cancer (HNBC-001): results from a multicenter, randomized controlled, open-label phase II 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 PO1-28-07.

Abstract PO1-19-11: Phase 3 Study of Tucatinib or Placebo in Combination With Trastuzumab and Pertuzumab as Maintenance Therapy for HER2+ Metastatic Breast Cancer (HER2CLIMB-05, Trial in Progress)

Abstract Background The current first-line (1L) standard of care (SOC) for human epidermal growth factor receptor 2-positive (HER2+) metastatic breast cancer (MBC) is trastuzumab (T) plus pertuzumab (P) and a taxane. Despite advances in 1L SOC, most patients progress during maintenance therapy with T+P. Tucatinib is a tyrosine kinase inhibitor (TKI) approved in combination with T and capecitabine for adults with HER2+ MBC, with and without brain metastases (BM). In HER2CLIMB, addition of tucatinib significantly prolonged progression-free survival (PFS) and overall survival (OS) in patients with HER2+ MBC and was well tolerated. Adding tucatinib also reduced the risk of disease progression or death in patients with untreated and/or active BM (Murthy et al. NEJM 2020, Curigliano et al. Ann Oncol 2022). HER2CLIMB-05 investigates whether adding tucatinib to 1L SOC as maintenance therapy will extend PFS while maintaining quality of life (QOL). Methods HER2CLIMB-05 (NCT05132582) is a phase 3, randomized, double-blind study evaluating tucatinib plus T+P as maintenance therapy for HER2+ MBC. Approximately 650 patients will be enrolled. Eligible patients will have advanced HER2+ disease, no progression on 4–8 cycles of prior 1L SOC, Eastern Cooperative Oncology Group Performance Status of 0 or 1, and no or asymptomatic BM. Exclusion criteria include prior treatment with anti-HER2 and/or anti-epidermal growth factor receptor TKI (prior SOC for early BC is permitted) or inability to undergo contrast magnetic resonance imaging of the brain. Patients will be randomized 1:1 to receive either tucatinib or placebo twice daily, with T+P once every 21 days. Patients with hormone receptor-positive disease may receive endocrine therapy. The primary endpoint is investigator-assessed PFS. Secondary endpoints include OS, time to deterioration of health-related QOL, central nervous system PFS, safety, and pharmacokinetic (PK) parameters. PFS and OS will be compared using a two-sided stratified log-rank test between treatment groups. Time-to-event endpoints will be summarized using the Kaplan–Meier method. PK and safety data will be summarized using descriptive statistics. Enrollment is ongoing in Austria, Chile, Greece, Italy, Japan, Poland, Portugal, Spain, the US, and several other European, APAC, and LATAM countries. This abstract was previously presented at ESMO-BC 2022, FPN (Final Publication Number): 415, by Veronique Dieras (reused with permission). Citation Format: Erika Hamilton, Junji Tsurutani, Giuseppe Curigliano, Miguel Martín, Ciara O'Sullivan, Joo Hyuk Sohn, Konstantinos Tryfonidis, Libero Santarpia, Shan Yang, Véronique Diéras. Phase 3 Study of Tucatinib or Placebo in Combination With Trastuzumab and Pertuzumab as Maintenance Therapy for HER2+ Metastatic Breast Cancer (HER2CLIMB-05, Trial in Progress) [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 PO1-19-11.

Abstract PO1-20-06: Phase 2 study of novel HER2-targeting, TLR7/8 immune-stimulating antibody conjugate (ISAC) BDC-1001 +/- pertuzumab in patients with HER2-positive metastatic breast cancer (MBC) previously treated with trastuzumab deruxtecan

Abstract Background: Therapies to effectively manage patients (pts) with metastatic HER2+ breast cancer have significantly improved over the years, but improvement is still needed in both efficacy and tolerability. BDC-1001 is an ISAC consisting of a trastuzumab biosimilar conjugated to a proprietary cell membrane impermeable TLR7/8 agonist via a non-cleavable linker, administered IV every 2 weeks. It is designed to trigger the innate immune system and generate a durable tumor-targeted adaptive immune response. Preclinical studies indicate that HER2-targeted ISACs elicit potent and durable immune-mediated antitumor efficacy, leading to complete tumor regression in a TLR- and Fc receptor-dependent manner [1]. Moreover, preclinical studies with a murine surrogate of BDC-1001 (trastuzumab-T785 ISAC) indicate improved anti-tumor activity with trastuzumab-T785 compared with trastuzumab/pertuzumab. In these preclinical studies, the combination of trastuzumab-T785 and pertuzumab demonstrated significantly enhanced efficacy in multiple HER2-expressing tumor models, including those with lower HER2 expression [1]. The addition of pertuzumab decreased the quantity of ISAC required for anti-tumor activity in the JIMT-1 HER2 IHC2+ model. Moreover, the combination of pertuzumab with the ISAC significantly increased the cytokine and chemokine concentrations in the tumor xenografts, compared with monotherapy or trastuzumab/pertuzumab, indicating enhanced myeloid activation in the tumor. These preclinical studies suggest that this combination may enhance the clinical activity of trastuzumab-based ISACs. The completed part of the BDC-1001 dose escalation trial (NCT04278144) demonstrated safety, PK and pharmacodynamic changes compatible with the ISAC mechanism of action, and a wide range of antitumor activity (incl. cases with breast cancer); resulting in a RP2D of 20 mg/kg q2w [2]. Two trials are underway, including a Phase 2 trial in other HER2+ malignancies, and a randomized Phase 2 trial with BDC-1001 alone and in combination with pertuzumab in patients with HER2-positive MBC previously treated with 2 or more prior anti-HER2 therapies, including trastuzumab deruxtecan. Methods: The Phase 2 multicenter, open-label, randomized study (BBI-20231001) is enrolling up to 66 pts with HER2-positive (ASCO/CAP guidelines 2018) MBC previously treated with 2 or more prior anti-HER2 therapies, including trastuzumab deruxtecan as one of the prior therapies. Pts must be 18 years or older, have measurable disease (RECIST v1.1), and have Eastern Cooperative Oncology Group performance status of 0 or 1. Pts will be administered BDC-1001 20 mg/kg every 2 weeks (IV q2w) and randomized 1:1 to receive BDC-1001 as a single agent or in combination with pertuzumab. The trial has a Simon 2-stage design within each arm. The primary objective is to determine the overall response rate per RECIST v1.1 of BDC-1001 alone and in combination with pertuzumab. Secondary objectives will evaluate safety, additional efficacy parameters, pharmacokinetics, and immunogenicity of BDC-1001 alone and in combination with pertuzumab. Exploratory objectives will include pharmacodynamic biomarkers in tumor tissue (baseline and on-treatment biopsies if feasible) and in peripheral blood to elucidate the mechanism of action and seek to identify biomarkers associated with BDC-1001 biological activity with or without pertuzumab. This study is expected to initiate accrual in 2H 2023. For additional information, please contact Bolt Biotherapeutics at 1-650-665-9295 or info@boltbio.com.

Abstract PO4-12-10: Sacituzumab Govitecan Toxicity Outcomes In Arab Patients with Metastatic Breast Cancer

Abstract Background: The Arab population is often underrepresented in clinical trials, which limits our knowledge of drug safety and efficacy in this population due to genetic variability that can affect drug metabolism and adverse events (AEs). Sacituzumab govitecan (SG) is approved for metastatic triple negative breast cancer (mTNBC), and recently hormone receptor positive metastatic breast cancer (HR+ MBC). Here we report toxicity outcomes and RDI in Arab population. Methods: A multi-center retrospective study of patients with mTNBC and HR+ MBC treated with SG from January 2021 until May 2023 was conducted. Demographics and clinical variables including site of metastases, prior lines of therapy, relative dose intensity (RDI), adverse events (AEs) were collected. For continuous variables, Mann-U Whitney and Kruskal Wallis tests were used to compare mean, median, standard deviation, and range. For categorical variables, Fisher's exact tests and Pearson Chi-square tests were used. SAS v9.4 was used to perform statistical analysis at a significance level of 0.05. Results: A total of 35 patients was enrolled. The median age at diagnosis of metastatic breast cancer was 39 years interquartile range (IQR) (35, 44). The median age at starting SG was 44.5 years IQR (38,50). The majority of patients (65%) had an Eastern Cooperative Oncology Group performance status (ECOG PS) of 1, (21%) of the patients had an ECOG PS of 0, and (15%) had an ECOG PS of 2. 48.6% received 3 or more lines of prior therapy in the metastatic setting while 51.4% received less than 3 lines of prior therapy in the metastatic setting. 77.1% of patients had 3 or &amp;gt; organs involved with metastatic disease, while 22.9% of patients had &amp;lt; 3 organ involved. The most common metastatic sites were the lung (54.3%), liver (62.9%), bone (68.6%), and brain (45.7%). The median RDI of SG was 100% for a sample of 34 individuals, with one missing value IQR (94%,100%). The rate of overall AEs was (77.1%), with the most common AEs being; neutropenia (44.4%), diarrhea (37.0%), anemia (22.2%), thrombocytopenia (22.2%), nausea (14.8%), and vomiting (7.4%). Garde 3 AEs rate was 34.3%. The most common grade 3 adverse events were diarrhea (11.4%), fatigue (5.7%), and alopecia (2.9%). The rate of treatment interruption and dose reduction due to AEs was 31.4%. Only one patient (2.9%) had to discontinue SG treatment due to adverse events. Conclusion: The study suggests that SG is safe and well-tolerated in young Arab patient population. The sample consisted of relatively young patients, which may reflect a reluctance to prescribe SG to older Arab patients. Caution should be exercised when generalizing the findings due to limitations of the study. Further studies with larger sample sizes are needed to validate these findings and to explore the efficacy of SG in Arab patients with mTNBC and HR+ MBC. Citation Format: Maymouna Altarturi, Kausar Suleman, Adhar AlSayed, Humaid Al-Shamsi, Aydah Alawadhi, Bassam Basuliamn, Sabah Alaklabi. Sacituzumab Govitecan Toxicity Outcomes In Arab Patients with Metastatic 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 PO4-12-10.