Progression-free Survival Benefit Research Articles

Divarasib in the Evolving Landscape of KRAS G12C Inhibitors for NSCLC.

Kristen Rat Sarcoma viral oncogene (KRAS) mutations are one of the most common oncogenic drivers found in 12-14% of non-small cell lung cancer (NSCLC) and 4% of colorectal cancer tumors. Although previously difficult to target, sotorasib and adagrasib are now approved for previously treated NSCLC patients with KRAS G12C mutations. In preclinical studies, divarasib was 5 to 20 times as potent and up to 50 times as selective as sotorasib and adagrasib. While sotorasib met its primary endpointin the phase III second line study against docetaxel, the progression-free survival (PFS) benefit was small and no overall survival (OS) benefit was observed. Adagrasib has demonstrated clinical benefitin the phase I/II KRYSTAL-1 study setting, however, 44.8% of patients reported grade 3 or higher toxicities. Divarasib has been studied in a phase I dose expansion cohort with promising efficacy [objective response (ORR) 53.4% and PFS 13.1 months]. Although most patients reported toxicities, the majority were low-grade and manageable with supportive care. Here we discuss these results in the context of the evolving KRAS G12C landscape.

Camrelizumab plus famitinib in previously chemo-immunotherapy treated patients with advanced NSCLC: results from an open-label multicenter phase 2 basket study

BackgroundThe combination of immune checkpoint inhibitors and antiangiogenic agents has been effective in treating multiple cancers. This was further explored in an open-label, multicenter phase 2 basket study (NCT04346381), which evaluated the antitumor activity and safety of camrelizumab (an anti-PD-1 antibody) plus famitinib (a receptor tyrosine kinase inhibitor) in patients with advanced solid tumors. We herein report the findings from the cohort of advanced NSCLC patients who progressed after treatment with platinum-doublet chemotherapy and immunotherapy.MethodsEligible patients were enrolled and treated with camrelizumab (200 mg once every 3 weeks via intravenous infusion) and oral famitinib (20 mg once daily). The primary endpoint was the objective response rate (ORR). Secondary endpoints included the disease control rate (DCR), duration of response (DoR), progression-free survival (PFS), overall survival (OS), and safety.ResultsForty patients were enrolled in this cohort, with a median follow-up duration of 11.5 months. Three patients (7.5%) achieved a partial response, and 29 patients (72.5%) achieved stable disease. The ORR and DCR with this combination regimen were 7.5% (95% CI, 1.6–20.4) and 80.0% (95% CI, 64.4–90.9), respectively. The median DoR was 12.1 months (95% CI, 10.3-not reached). The median PFS was 5.4 months (95% CI, 4.1–7.5), and the median OS was 12.1 months (95% CI, 9.1–16.7). The estimated 12-month OS rate was 51.5% (95% CI, 34.9–65.9). The most frequent grade 3 or higher treatment-related adverse events occurring in more than 5% of patients included hypertension (27.5%), palmar-plantar erythrodysesthesia syndrome (10%), decreased neutrophil count (10%), and proteinuria (7.5%).ConclusionCamrelizumab plus famitinib demonstrated favorable benefits in PFS and OS, along with manageable safety profiles, in patients with advanced NSCLC who progressed after platinum-doublet chemotherapy and immunotherapy. This finding warrants further exploration.

Abstract PO5-21-09: Clinical outcomes by age subgroups in the phase 3 TROPiCS-02 study of sacituzumab govitecan vs treatment of physician’s choice in HR+/HER2‒ metastatic breast cancer

Abstract Background Sacituzumab govitecan (SG) is a Trop-2directed antibody-drug conjugate approved for second-line or later (2L+) treatment of metastatic triple-negative breast cancer in multiple countries and for 2L+ treatment of HR+/HER2‒ (IHC 0, 1+, or 2+/ISH) metastatic breast cancer (mBC) in the US. SG significantly improved progression-free survival (PFS) and overall survival (OS) vs treatment of physician’s choice (TPC) in patients (pts) with pretreated, endocrine-resistant HR+/HER2‒ mBC in the TROPiCS-02 study. The incidence of HR+/HER2‒ mBC increases with age, especially after 65, and older pts often have poorer prognosis due to comorbidities, increased toxicity, and reduced efficacy of chemotherapy. In TROPiCS-02, pts aged ≥ 65 years (yr) derived consistent PFS benefit and clinically meaningful improved OS with SG vs TPC. In this analysis, we present additional efficacy and safety outcomes by age subgroup. Methods Pts with HR+/HER2‒ mBC who had received at least 1 endocrine therapy, taxane, and CDK4/6 inhibitor, and 2 to 4 prior lines of chemotherapy for mBC, were randomized to either SG (10 mg/kg IV days 1 and 8, Q3W) or TPC. The primary end point was PFS, and secondary end points included OS, objective response rate (ORR), and safety. A post hoc analysis was conducted by age subgroups (< 65 vs ≥ 65, < 75 vs ≥ 75). Results In total, 543 pts were randomized to the SG (n = 272; 73 [27%] ≥ 65, 16 [6%] ≥ 75) and TPC (n = 271; 67 [25%] ≥ 65, 8 [3%] ≥ 75) groups. Baseline characteristics were generally similar across treatment arms in each age subgroup, but a higher proportion of pts had performance status 1 vs 0 in the ≥ 65 vs < 65 and ≥ 75 vs < 75 subgroups, respectively. The data cutoff date was July 1, 2022. SG demonstrated longer median PFS and OS vs TPC across age subgroups. Hazard ratios (HR) for PFS with SG vs TPC were 0.69, 0.59, 0.70, and 0.30 for the < 65, ≥ 65, < 75, and ≥ 75 subgroups, respectively (Table). The HR for OS were 0.81, 0.80, 0.82, and 0.56 in these subgroups, respectively (Table). Median duration of response (DoR) was also longer with SG vs TPC across age subgroups, although median DoR was not estimable in the ≥ 75 subgroup (Table). ORR was higher with SG vs TPC, except in the ≥ 75 subgroup (Table). Safety was generally similar with SG vs TPC across subgroups with the following differences. Grade ≥ 3 treatment-emergent adverse events were more common in the ≥ 75 subgroup than the other subgroups (SG, 81% in ≥ 75 vs 68%-73% for all others; TPC, 71% in ≥ 75 vs 60%-61% for all others). TEAEs leading to dose reduction were also more common in pts treated with SG in the ≥ 75 subgroup, but were consistent across other subgroups (Table). However, sample sizes in the ≥ 75 subgroup were small, which limits interpretation (Table). TEAEs leading to treatment discontinuation were more common in older pts, irrespective of treatment group (Table). Conclusions SG showed benefit in PFS and OS vs TPC in pts with HR+/HER2‒ mBC across age subgroups, consistent with the intent to treat population. SG was associated with a slight increase in toxicity for elderly pts, as expected. SG demonstrated a favorable benefit/risk profile, with efficacy benefit and acceptable toxicity, for elderly pts. Table. Citation Format: Aditya Bardia, Peter Schmid, Sara Tolaney, Frederik Marmé, Javier Cortés, Theresa Valdez, Hao Wang, Wendy Verret, Hope Rugo. Clinical outcomes by age subgroups in the phase 3 TROPiCS-02 study of sacituzumab govitecan vs treatment of physician’s choice in HR+/HER2‒ 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 PO5-21-09.

Abstract PO3-20-02: Olaparib front line therapy with endocrine therapy in locally advanced unresectable or in metastatic breast cancer: OFELIA TRIAL

Abstract INTRODUCTION: Currently, patients with recurrent or metastatic hormone-sensitive breast cancer are treated with endocrine therapy (ET) in combination with cyclin inhibitors, as it has been shown to improve both overall survival and progression-free survival. However, it has been observed that patients with gBRCA1 or gBRCA2 mutations, who receive treatment with endocrine therapy and CDK4/6 inhibitors, have lower OS and lower PFS compared to those without mutations. These findings could be due to the presence of higher cyclin E mRNA levels, which encode the protein that stimulates CDK2 activity provoking a resistance to CDK4/6 inhibitors. Having this said, the use of PARP inhibitors a potential first-line therapeutic option in combination with endocrine therapy could be an option to be re evaluated. JUSTIFICATION: PARP inhibitors (iPARP) are recommended in international guidelines as second-line palliative treatment and also as adjuvant management in the case of Olaparib. The use of iPARP is approved only as a second-line treatment in HER2 hormone-sensitive breast cancer, according to the results of the EMBRACA and OlympiAD clinical trials. However, these two clinical trials were not designed to evaluate its effectiveness as first-line palliative treatment. Given that patients with gBRCA mutations have lower overall survival when administered cyclin inhibitors (iCDK 4/6) + Endocrine therapy (ET) compared to those without mutations, it is necessary to reevaluate the use of iPARP as first-line palliative treatment in conjunction with ET, with the expectation of achieving a similar objective response rate and progression-free survival. OBJECTIVE: To Determine the ORR in patients with recurrent or metastatic hormone-sensitive HER2-negative breast cancer managed with PARP inhibitors + Endocrine therapy. HYPOTHESIS: The use of PARP inhibitors in combination with endocrine therapy will have an objective response rate of 60% or higher in both early stages and advanced disease. METHODOLOGY: Phase 2 open-label, multicenter clinical trial. Study Population: Cohort : All pre- or postmenopausal patients with a diagnosis of recurrent or metastatic hormone-sensitive HER2-negative breast cancer with gBRCA1 and/or gBRCA2 mutation. Sample: The inclusion of patients will be based on meeting the inclusion criteria. We plan to achieve an ORR of at least 60% with an acceptable minimum of 40%. Assuming a one-sided alpha level of 0.05 and statistical power of 80%, a two-stage Simon design was used to calculate the required sample size. In the first stage, a minimum of 23 patients is assumed, of which 14 patients need to achieve the desired response rate to proceed to the second stage. In the second stage, an additional 28 patients will be added to obtain a total sample size of 51 patients. The objective response rate will be evaluated using RECIST v1.1 criteria at 8 weeks after initiating treatment, with continued assessment during the first year, followed by assessments every 12 weeks during the second and third year, and then every 24 weeks until progression or toxicity. EXPECTED RESULTS: PARP inhibitors + Endocrine therapy will have a similar ORR as reported with cyclin inhibitors + Endocrine therapy, as well as a benefit in progression-free survival. Citation Format: Carlos Arturo González Núñez, Paula Cabrera-Galeana, Juan Enrique Bargalló Rocha, Rafael Vazquez-Romo, Sergio Aguilar-Villanueva, Alexandra Garcilazo, Areli Velazquez-Martinez, Andrea Maliachi, Ruben Rodriguez. Olaparib front line therapy with endocrine therapy in locally advanced unresectable or in metastatic breast cancer: OFELIA 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 PO3-20-02.

Abstract PS02-01: Efficacy, safety, and quality of life with ribociclib + endocrine therapy in elderly patients with HR+/HER2– advanced breast cancer across the MONALEESA-2, -3, and -7 trials

Abstract Background: Ribociclib (RIB) + endocrine therapy (ET) showed statistically significant progression-free survival (PFS) and overall survival (OS) benefits in MONALEESA-2, -3, and -7 in patients (pts) with HR+/HER2− advanced breast cancer (ABC). Here, we report efficacy, safety, and quality of life (QOL) with RIB + ET in elderly pts in the MONALEESA trials. Methods: Data were pooled from the MONALEESA-2, -3, and -7 trials of pre- and postmenopausal pts with HR+/HER2− ABC treated with first-line RIB + ET or placebo (PBO) + ET. The tamoxifen cohort in MONALEESA-7 and pts with early relapse were excluded from this analysis. PFS, OS, and time to first chemotherapy (TTC) were analyzed in pts <65 y, 65- <75 y, and ≥75 y using Kaplan-Meier methods. Time to definitive deterioration (TTD) by ≥10 points in global health status (GHS) was analyzed across age subgroups using Kaplan-Meier methods. Results: Of the 1229 pts included in this analysis, 773 (62.9%) were <65 y, 335 (27.3%) were 65- <75 y, and 121 (9.8%) were ≥75 y. There were minor differences in baseline characteristics between the age groups: slightly higher % of pts in the ≥75 y group with a ECOG status of 1 and slightly higher % of de novo disease in the <65 y group (Table). Regardless of age, a PFS and OS benefit was seen with RIB + ET vs PBO + ET (Table). RIB + ET also delayed the median TTC in all age groups. In the RIB + ET group, the most common first subsequent antineoplastic treatment was hormonal therapy alone ( <65 y, 26.3%; 65- <75 y, 41.6%; ≥75 y, 38.1%). In the ≥75 y subgroup, pts in the RIB + ET arm (6.3%) less frequently used chemotherapy alone as the first subsequent antineoplastic treatment vs the PBO + ET (24.5%) arm. In pts <65 y, safety results were consistent with those in the overall trial population. In pts 65- <75 y and ≥75 y, the most common any grade adverse events (AEs) with RIB + ET vs PBO + ET were neutropenia (67.6% vs 5.4% and 52.9% vs 3.8%), nausea (52.7% vs 32.0% and 52.9% vs 40.4%), fatigue (42.0% vs 38.1% and 36.8% vs 21.2%), and diarrhea (39.9% vs 30.6% and 48.5% vs 32.7%). For RIB + ET vs PBO + ET, rates of grade 3/4 febrile neutropenia ( <65 y, 1.2% vs 0.3%; 65- <75 y, 1.1% vs 0; ≥75 y, 2.9% vs 0), all grade interstitial lung disease ( <65 y, 1.0% vs 0.6%; 65- <75 y, 2.7% vs 0.7%; ≥75 y, 7.4% vs 0), and all grade QT prolongation ( <65 y, 9.1% vs 2.9%; 65- <75 y, 11.2% vs 4.1%; ≥75 y, 16.2% vs 1.9%) were numerically higher in pts 65- <75 y and ≥75 y than in pts <65 y. Rates of discontinuation due to AEs with RIB + ET vs PBO + ET were 14.6% vs 3.1% in pts <65 y, 19.7% vs 6.8% in pts 65- <75 y, and 41.2% vs 7.7% in pts ≥75 y. In pts who discontinued treatment due to AEs, the percentage of pts without prior dose reduction was 34.4% in pts <65 y, 40.5% in pts 65- <75 y, and 50.0% in pts ≥75 y. TTD in GHS was prolonged with RIB + ET vs PBO + ET in pts <65 y. In pts 65- <75 y and ≥75 y, TTD was generally similar with RIB + ET vs PBO + ET (Table). Conclusions: This pooled analysis of the MONALEESA-2, -3, and -7 trials demonstrated PFS and OS benefits with RIB + ET in elderly pts consistent with those observed in younger pts. Across age subgroups, treatment with RIB + ET also delayed TTC. Overall, RIB was well tolerated in elderly pts, with a safety profile consistent with what is anticipated for an older patient population. Additionally, there was no difference in TTD in GHS with RIB + ET vs PBO + ET in pts 65- <75 y and pts ≥75 y. Citation Format: Lowell Hart, Seock-Ah Im, Sara Tolaney, Mario Campone, Timothy Pluard, Berta Sousa, Gilles Freyer, Thomas Decker, Kevin Kalinsky, Astrid Thuerigen, Melissa Gao, Huilin Hu, Sherko Küemmel. Efficacy, safety, and quality of life with ribociclib + endocrine therapy in elderly patients with HR+/HER2– advanced breast cancer across the MONALEESA-2, -3, and -7 trials [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 PS02-01.

Abstract GS01-12: MONARCH 3: Final overall survival results of abemaciclib plus a nonsteroidal aromatase inhibitor as first-line therapy for HR+, HER2- advanced breast cancer

Abstract Background: Abemaciclib is approved both for high-risk early breast cancer as well as advanced breast cancer (ABC) in the first- and second-line setting. In MONARCH 2, the addition of abemaciclib to fulvestrant significantly improved both progression-free survival (PFS) and overall survival (OS) in patients with HR+, HER2- ABC with disease progression on prior endocrine therapy (ET). In MONARCH 3, the addition of abemaciclib to a nonsteroidal aromatase inhibitor (NSAI) significantly improved PFS (HR, 0.540; 95% CI, 0.418-0.698; p=0.000002) as initial therapy in HR+, HER2- ABC. At the last interim OS analysis (~252 events, at 5.8 years follow-up [FU]), a numerically favorable median OS difference (12.6 months) was observed (HR, 0.754; 95% CI, 0.584-0.974; p=0.0301, non-significant [NS]). Here, we present the final OS analysis of MONARCH 3 (NCT02246621). Methods: MONARCH 3 is a randomized, double-blind, Phase 3 study of abemaciclib + NSAI (anastrozole or letrozole) vs placebo + NSAI in postmenopausal women with HR+, HER2- ABC without prior systemic therapy in the advanced setting. OS was a gated secondary endpoint and chemotherapy-free survival (CFS) an exploratory endpoint. Final OS analysis was planned after approximately 315 OS events had occurred in the intent-to-treat (ITT) population with a split alpha between the ITT population and the subgroup with visceral disease (sVD) according to a prespecified graphical testing scheme. Kaplan-Meier method and stratified Cox proportional hazards models were used for time-to-event analyses. All reported p-values are two-sided. Results A total of 493 women were randomized 2:1 to receive abemaciclib + NSAI (n=328) or placebo + NSAI (n=165). After a median FU of 8.1 years, 7% of patients were still receiving treatment in the abemaciclib arm vs 3% in the placebo arm. In the ITT population, 314 OS events were observed (198 deaths among 328 patients [60%] in the abemaciclib arm and 116 among 165 [70%] in the placebo arm; HR, 0.804; 95% CI, 0.637-1.015; p=0.0664, NS). Median OS was 66.8 months in the abemaciclib arm and 53.7 months in the placebo arm, a numerical difference of 13.1 months in the ITT population. In the sVD, 178 events were observed (113 deaths among 173 patients [65%] in the abemaciclib arm and 65 among 90 [72%] in the placebo arm; HR, 0.758; 95% CI, 0.558-1.030; p=0.0757, NS). Median OS was 63.7 months in the abemaciclib arm and 48.8 months in the placebo arm, a numerical difference of 14.9 months in the sVD. Consistent OS differences were observed across prespecified subgroups. PFS benefit was sustained (median 29.0 vs 14.8 months; HR, 0.535; 95% CI, 0.429-0.668; nominal p<0.0001) with substantial difference in 6-year PFS rates (23.3% vs 4.3% for abemaciclib vs placebo). CFS was also improved with abemaciclib vs placebo (median 46.7 vs 30.6 months; HR, 0.693; 95% CI, 0.557-0.863; nominal p=0.0010). No new safety signals were observed with longer term use. Conclusion In patients with HR+, HER2- ABC, abemaciclib in combination with a NSAI resulted in numerically longer OS compared to NSAI alone; however, statistical significance was not reached after a median FU of 8.1 years. The clinically meaningful improvement in median OS (>13 months) combined with the sustained significant improvement in median PFS (>14 months) and substantial extension in median CFS (>16 months) continue to support the use of abemaciclib in combination with NSAI as first-line therapy in ABC. Citation Format: Matthew Goetz, Masakazu Toi, Jens Huober, Joo Hyuk Sohn, Olivier Trédan, Inhae Park, Mario Campone, Shin-Cheh Chen, Luis Manual Manso, Shani Paluch-Shimon, Orit C. Freedman, Valerie Andre, Abhijoy Saha, Gertjan van Hal, Ashwin Shahir, Hiroji Iwata, Stephen RD Johnston, Joyce O'Shaughnessy, Xavier Pivot, Sara Tolaney, Sara Hurvitz, Antonio Llombart. MONARCH 3: Final overall survival results of abemaciclib plus a nonsteroidal aromatase inhibitor as first-line therapy for HR+, HER2- advanced 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 GS01-12.

Abstract PS17-03: Capivasertib and fulvestrant for patients with aromatase inhibitor-resistant HR positive/HER2-negative advanced breast cancer: exploratory analysis of PFS by AKT pathway gene from the Phase 3 CAPItello-291 trial

Abstract Background: In the Phase 3 randomized, double-blind CAPItello-291 trial, the addition of capivasertib (a potent, selective pan-AKT inhibitor) to fulvestrant in patients with aromatase inhibitor-resistant, hormone receptor (HR)-positive/human epidermal growth factor receptor 2 (HER2)-negative (HER2− defined as immunohistochemistry [IHC] 0, or 1-positive or IHC2-positive/in situ hybridization-negative) advanced breast cancer (ABC) significantly improved progression-free survival (PFS) versus placebo + fulvestrant (hazard ratio [HR] 0.60, 95% confidence interval [CI] 0.51–0.71; p< 0.001). PFS benefit was observed in patients with detectable AKT pathway alterations (HR 0.50, 95% CI 0.38–0.65; p< 0.001) and without (0.70; 95% CI; 0.56–0.88). Here, we report PFS by gene within the AKT pathway-altered population. Methods: Patients were randomized 1:1 to receive fulvestrant (500 mg intramuscularly on days 1 and 15 of cycle 1, and day 1 of each subsequent 28-day cycle) with either placebo or capivasertib (400 mg twice daily; 4 days on, 3 days off). AKT pathway-alteration status (at least one qualifying alteration in the genes PIK3CA, AKT1, or PTEN) was determined post-randomization, using next-generation sequencing in tumor tissue. HRs were calculated using Cox proportional hazards models. Data cut-off Aug 15, 2022. Results: Of the 708 patients randomized to treatment, 289 (41%) had AKT pathway-altered tumors (capivasertib-fulvestrant n=155; placebo-fulvestrant n=134). In the AKT pathway-altered population, 43% had liver metastases and 40% primary endocrine therapy resistance. Prior therapy for advanced disease included: 89% of patients with ≥1 line of prior treatment, 71% with a prior cyclin-dependent kinase 4 and 6 inhibitor, and 18% with prior chemotherapy. Baseline characteristics were broadly balanced between treatment groups. Most patients with an AKT pathway-altered tumor had only one detectable alteration (272/289, 94%). Thirteen patients (capivasertib-fulvestrant n=4; placebo-fulvestrant n=9) had co-occurring PIK3CA and PTEN alterations, and four patients (capivasertib-fulvestrant n=2; placebo-fulvestrant n=2) had co-occurring PIK3CA and AKT1 alterations. Consistent PFS benefit of capivasertib-fulvestrant over placebo-fulvestrant was observed across all alterations (Table). The safety profile of capivasertib-fulvestrant in the AKT pathway-altered population was consistent with the overall population. Conclusions: Compared with fulvestrant alone, the addition of capivasertib to fulvestrant provided a consistent PFS benefit across alterations in all three key genes within the AKT pathway in patients with HR-positive/HER2-negative ABC. https://clinicaltrials.gov/: NCT04305496 Funding: CAPItello-291 is sponsored by AstraZeneca. Editorial acknowledgment: AstraZeneca-funded medical writing support was provided by Suzanne Patel, Ph.D., from BOLDSCIENCE Inc. Capivasertib was discovered by AstraZeneca subsequent to a collaboration with Astex Therapeutics (and its collaboration with the Institute of Cancer Research and Cancer Research Technology Limited). Table. Citation Format: Sacha Howell, Hope Rugo, Mafalda Oliveira, Florence Dalenc, Javier Cortés, Henry Gómez, Xichun Hu, Komal Jhaveri, Petr Krivorotko, Sibylle Loibl, Serafin Morales Murillo, Meena Okera, Yeon Park, Joo Hyuk Sohn, Masakazu Toi, Eriko Tokunaga, Lyudmila Zhukova, Andrew Lloyd, Elza de Bruin, Coumaran Egile, Celina D’Cruz, Nicholas Turner. Capivasertib and fulvestrant for patients with aromatase inhibitor-resistant HR positive/HER2-negative advanced breast cancer: exploratory analysis of PFS by AKT pathway gene from the Phase 3 CAPItello-291 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 PS17-03.

Abstract PO3-17-12: Safety and efficacy of Atezolizumab in combination with nab-Paclitaxel in patients with PD-L1 positive metastatic or locally advanced triple-negative breast cancer: A pan-UK cancer centre experience

Abstract BACKGROUND Within the United Kingdom (UK), combination chemo-immunotherapy with Atezolizumab and nab-Paclitaxel is National Institute for Health and Care Excellence (NICE) approved as a first line palliative systemic treatment option for patients with advanced triple-negative breast cancer (aTNBC) with programmed death-ligand 1 (PD-L1) expression ≥1%. Trials demonstrated progression-free survival (PFS) and overall survival (OS) benefits. Treatment-related toxicities may impact on quality of life and result in treatment delay or discontinuation. We conducted a National Service Evaluation (SE) to assess the safety and efficacy in a “real-world” dataset. METHODS Data from patients with aTNBC who received Atezolizumab/nab-Paclitaxel between 9th March 2019 and 2022 across 10 UK Cancer Centres were analysed. All grade 1-4 toxicities were recorded in accordance with Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 scoring system. Participation was contingent on local approval for this project, and data transferred following receipt of a data sharing agreement. Kaplan-Meier curves for PFS and OS were calculated. RESULTS 129 patients were included in the analysis with a median age of 55 (30-82). 42.6% (n=55) had a PS of 0, 51.2% (n=66) a PS of 1 and 3.9% (n=5) had a PS of 2. Atezolizumab/nab-Paclitaxel was given in the first line setting in most patients (84.5%, n= 109), but in 15.5% (n=20) in the second line setting (privately insured). 21.7% (n=28) of patients presented with de novo metastatic disease, 58.1% (n=75) of patients were post-menopausal and 6.2% (n=8) had a BRCA1 or 2 mutation. 76.7% of patients (n=99) had previous neo-/adjuvant treatment in the non-metastatic setting: 55.8% had prior treatment with a taxane, 51.2% anthracycline, 22.5% platinum, and 66.7% had prior radiotherapy. 83.7% (n= 108) had invasive ductal breast cancer, and 84.5% (n=109) presented with 0-3 number of metastatic sites with 15.5% (n=20) having ≥ 4 metastatic sites. Here, the nodal metastatic site dominated in 78.3% of patients. Grade ≥ 3 events occurred in 21.7% (n=28) of patients. These were decreased neutrophil count (10.1%, n=13), pyrexia (2.3%, n=3), diarrhoea (1.6%, n=2), hypothyroidism (1.6%, n=2), peripheral neuropathy (1.6%, n=2), anaemia (1.6%, n=2), GGT rise (0.8%, n=1), fatigue (0.8%, n=1), hypophysitis (0.8%, n=1), pneumonitis (0.8%, n=1), nausea (0.8%, n=1), mucositis (0.8%, n=1), platelet count decreased (0.8%, n=1), infections (0.8%, n=1). Increased rates of Grade ≥ 3 colitis (2.3%, n=3) and hepatitis (3%, n=2.3) were observed. 20.2% (n=26) of patients required steroids to treat toxicities. Reason for treatment discontinuation included in 58.1% (n=75) disease progression, and 7.8% (n=10) unacceptable toxicity. In 22.5% of patients’ treatment was still ongoing at time of data lock. At approximately 12 weeks, 7.8% of patients had a complete and 51.2% a partial response, 10.1% had stable and 22.5% progressive disease and for 8.5% the response was not known as they have not yet reached 12 weeks since treatment start. Median PFS was 5 months and OS was 14 months. CONCLUSIONS The toxicity profile of Atezolizumab/nab-Paclitaxel was comparable to literature, however, both PFS and OS were shorter. In comparison to the IMpassion130 trial data, patients within this national SE project were less fit and more heavily pre-treated. A higher number of any grade hyperthyroidism and fatigue, and of grade ≥ 3 colitis and hepatitis were noticed. Baseline patient characteristics XX- XX Citation Format: Jasmin V Waterhouse, Alexandra Holdich, Florentia Mina, Mariam Obeid, Kroopa Joshi, Sophie Barrett, Lavarniya Rajakumar, Gemma McCormick, Sally Seymour, Panagiotis Koliou, Rushan Sylva, Olubukola Ayodele, Ashram Gautam, Jenny Smith, Jenny McKeon, Thomas Strawson-Smith, Rosalie Douglas, Annabel Borley, Apostolos Konstantis, Sophie McGrath. Safety and efficacy of Atezolizumab in combination with nab-Paclitaxel in patients with PD-L1 positive metastatic or locally advanced triple-negative breast cancer: A pan-UK cancer centre experience [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 PO3-17-12.

Abstract PO3-05-10: Efficacy and safety of eribulin plus gemcitabine in second-line or beyond for patients with HER2-negative metastatic breast cancer (MBC): A multi-center, open-label, single-arm, phase II study

Abstract Background: Eribulin is a halichondrin non-taxane inhibitor of microtubule dynamics approved in China for advanced breast cancer patients who have received at least two prior chemotherapy treatments. The combination of eribulin and gemcitabine has demonstrated a similar progression-free survival (PFS) benefit as paclitaxel plus gemcitabine, with less neurotoxicity, for patients with MBC who have not received prior cytotoxic chemotherapy. However, the effect of eribulin plus gemcitabine on PFS in second line or beyond remains unclear. Methods: This open-label, single-arm, phase II study (NCT05263882) was conducted at 13 institutions in China. Eligible patients had histologically confirmed HER2-negative MBC and had received at least one prior taxane-containing chemotherapy regimen for advanced disease, and anthracycline-containing regimens in the adjuvant setting. Patients received intravenous infusions of eribulin (1.4 mg/m2) and gemcitabine (1.0 g/m2) on days 1 and 8 of a 21-day cycle. Efficacy outcomes, including PFS, objective response rate (ORR), and disease control rate (DCR), were assessed using RECIST v1.1. Adverse events (AEs) were graded according to NCI-CTC version 5.0. Results: A total of 65 patients were enrolled from November 2021 to May 2023; 47 (72.3%) had HR+/HER2- and 18 (27.7%) had triple-negative MBC. The median patient age was 50 years (range: 31-68), and the sites of metastasis were the bone (70.8%), liver (58.5%), lymph nodes (50.8%), lung (43.1%) and brain (10.8%). Patients had received a median of 3 prior lines of systemic treatment, 2 lines of chemotherapy, and 1 line of endocrine treatment. Among all patients, the ORR was 52.3%, the DCR was 92.3% and the median PFS was 7.6 months (Table). For the HR-positive subgroup, the median PFS was 8.4 months, while for the triple-negative subgroup, it was 7.6 months. Among patients who had received prior CDK4/6 inhibitor treatment, the median PFS was 7.2 months. In the subgroup of patients who had not received CDK4/6 inhibitor treatment, the median PFS had not been reached. The most common grade 3-4 AEs were hematological, including neutropenia (41.6%), leukopenia (33.9%), anemia (23.1%), and thrombocytopenia (15.4%). No grade ≥3 perceived AEs were reported. Conclusion: Eribulin plus gemcitabine was effective in heavily pretreated patients with HER2- MBC, while maintaining a predictable and manageable safety profile. Table. Summary of efficacy outcomes Citation Format: PeiJian Peng, Xiao-Lu Xu, Jin-Cai Zhong, Jin-Hui Ye, Zhi-Hui Wang, Hong Wang, Hong Lin, Cai-Wen Du, Guorong Zou, Jie Ouyang, Ying-Ying Shi, Fei Xu, Geng-Sheng Yu, Yong-Kui Lu, Yong-Xia Wang, Shi-En Cui, Lu-Zhen Li. Efficacy and safety of eribulin plus gemcitabine in second-line or beyond for patients with HER2-negative metastatic breast cancer (MBC): A multi-center, open-label, single-arm, phase II study [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 PO3-05-10.

Abstract PO1-04-12: Palbociclib versus ribociclib in first-line treatment of patients with hormone-receptor positive HER2 negative advanced breast cancer – real world outcome data from the German registry platform OPAL

Abstract Introduction CDK4/6 inhibitors (CDKi) plus endocrine therapy (ET) are standard of care in first-line (1L) treatment of hormone receptor-positive (HR+) HER2-negative (HER2-) advanced breast cancer (ABC). In the pivotal trials the three CDK4/6i (palbociclib, ribociclib and abemaciclib) + ET showed similar progression-free survival (PFS) benefit over ET alone. However, other than ribociclib, palbociclib failed to demonstrate overall survival (OS) benefit. As patient (pts) characteristics differed between the trials, especially in the number of pts with treatment-free interval (TFI) of < 12 months after end of adjuvant ET, head-to-head comparisons of the CDKi are of clinical interest. Here we analyze the outcome of pts treated with palbociclib + ET or ribociclib + ET with real-world data from OPAL. Methods OPAL (NCT03417115) is a prospective observational, open, longitudinal multicenter cohort study (clinical registry) in Germany. Pts with ABC and early breast cancer can be recruited at start of their first systemic treatment. There are no treatment restrictions. Sites from all medical sectors can participate in OPAL (medical and gynecologic oncologists from outpatient centers and hospitals). Details on all (sequential) treatments, patient and tumor characteristics, biomarker testing, clinical and patient-reported outcomes are collected. Follow-Up is until death or up to 5 years. Between 01/2018 and 07/2021 1049 pts with HR+ HER2- ABC were recruited by 143 sites. Database cut was on 31/08/2022. 384 pts received palbociclib + ET and 231 pts received ribociclib + ET as 1L treatment. All endocrine combination partners including switch of ET during first line therapy was allowed, whereas switch of CDK4/6i (n=25) were excluded. PFS in registries can differ from PFS in clinical trials, since the RECIST criteria are usually not applied in routine care. PFS in registries represents the time to clinically relevant progression in routine care. PFS and OS were estimated using the Kaplan-Meier method. To adjust for confounding, inverse probability of treatment weighting (IPTW) by propensity score analysis was used to compare PFS and OS between 1L palbociclib+ET and ribociclib+ET. IPTW was performed for the following variables: age, menopausal status, ECOG, any comorbidity, Charlson comorbidity index, metastatic stage, type of metastasis, number of metastatic sites, estrogen-/progesterone status, IHC status, previous chemo-/endocrine therapy, kind of endocrine combination partner, disease-free interval, and treatment-free interval. Results From 2018 to 2021, the proportion of CDK4/6i increased from 68% to 86% in 1L of HR+HER2- ABC. Overall, palbociclib was used in 44% and ribociclib in 26% of all first-line treatments in OPAL. Median age of pts receiving palbociclib/ribociclib was 66/68 years and for 77/81% of pts at least one comorbidity was documented. 37/35% of pts already had metastasis at diagnosis (M1) and 25/26% of pts had a TFI < 12 months. After IPTW, the two treatment groups were comparable for all tested characteristics. 42/46% of patients had a progression (palbociclib/ribociclib group). IPTW-adjusted median PFS was 25.1 months (95% Confidence interval (CI) 20.1 – 30.1) for the palbociclib and 27.0 months (95%-CI 21.1 – 31.6) for the ribociclib group. Hazard ratio was 0.91 (0.71 – 1.17) for palbociclib versus ribociclib. 26/29% of patients had an OS event (palbociclib/ribociclib group). IPTW-adjusted median OS was 36.7 months (95%-CI 33.0 – NA) for the palbociclib and 36.6 months (95%-CI 33.1 – NA) for the ribociclib group. Hazard ratio was 0.95 (0.69 - 1.30) for palbociclib versus ribociclib. Conclusions This analysis of real word data in the OPAL registry platform showed similar PFS and OS for palbociclib + ET compared to ribociclib + ET, when adjusted for a wide range of potential confounding variables. Further analyses will investigate whether one drug showed favorable results in certain subgroups of pts. Citation Format: Marc Thill, Mark-Oliver Zahn, Anja Welt, Arnd Nusch, Matthias Zaiss, Kathrin Engelken, Gabriele Kaltenecker, Kai Ringwald, Katja Gratzke, Lisa Kruggel, Martina Jänicke, Holger Schulz, Christoph Losem, Volker Hagen, Roland Fricker, Elmar Stickeler, Nadia Harbeck, Achim Wöckel, Thomas Decker. Palbociclib versus ribociclib in first-line treatment of patients with hormone-receptor positive HER2 negative advanced breast cancer – real world outcome data from the German registry platform OPAL [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 PO1-04-12.

Abstract RF01-01: SERENA-3: A randomized pre-surgical window of opportunity study assessing dose and duration of camizestrant treatment in post-menopausal women with ER-positive, HER2-negative primary breast cancer

Abstract Background Camizestrant, a next-generation oral selective estrogen receptor (ER) degrader (SERD) and pure ER antagonist, has demonstrated statistically significant and clinically meaningful progression-free survival (PFS) benefit over fulvestrant at both 75 and 150 mg once-daily doses in the Phase 2 SERENA-2 (NCT04214288) study in post-menopausal women with ER+ HER2- advanced breast cancer. SERENA-3 (NCT04588298) was established to explore the biological effects of three camizestrant dose levels in post-menopausal women with ER+ HER2- primary breast cancer. Methods Post-menopausal women with ER+ HER2- primary breast cancer scheduled to undergo curative intent surgery were randomly assigned in Stages 1 and 2 to pre-surgical treatment with camizestrant at 75, 150 or 300 mg once daily for 5 to 7 days or, in a sequential Stage 3, randomly assigned to camizestrant at 75 or 150 mg once daily for 12 to 15 days. Image-guided tumor biopsies were accessed as pre-treatment samples, while on-treatment ultrasound-guided tumor biopsies were obtained on the last day of camizestrant treatment. The primary objective was to explore the effect of camizestrant on ER expression by comparison of pre-treatment and on-treatment biopsies as assessed by immunohistochemistry (IHC) H-score. Secondary objectives included assessment of Ki67 and progesterone receptor (PgR) expression, and also of safety and tolerability, with exploratory pharmacodynamic (PD) assessment using other transcriptomic and proteomic technologies. The study was undertaken in 17 centers across 3 countries (Georgia, Mexico and the United Kingdom). Results 135 patients were randomized and received treatment. 76 patients received camizestrant for 5 to 7 days at doses of 75 mg (n=30), 150 mg (n=33), and 300 mg (n=13); 59 received camizestrant for 12 to 15 days at doses of 75 mg (n=30) and 150 mg (n=29). Baseline disease characteristics, and ER, Ki67 and PgR levels were well balanced across arms and stages. Pharmacokinetic (PK) observations in all stages were commensurate with steady-state predictions derived from previous studies. PD data for ER and Ki67 are shown in Table 1. Camizestrant reduced ER H-score by approximately 65% irrespective of dose or duration. While the 75 mg dose reduced Ki67 score to a lesser degree than 150 mg and 300mg after 5–7 days exposure, after 12–15 days exposure 75 and 150 mg reduced Ki76 score to a similar substantial degree (82% reduction). PD results assessed by additional transcriptomics and proteomics assays were concordant with the IHC analyses. No serious adverse events were reported. All treatment-emergent adverse events were grade 1, apart from one patient with a grade 2 visual impairment, and one patient with grade 3 diarrhea. Conclusions SERENA-3 is the first study investigating the effect of multiple dose levels of camizestrant with different treatment durations on ER, Ki67 and PgR expression in post-menopausal women with primary ER+ HER2˗ breast cancer. SERENA-3 demonstrated that the 75 mg dose of camizestrant achieves maximal levels of ER degradation and Ki67 suppression. Together with SERENA-2, this provides strong evidence supporting 75 mg as the optimal dose of camizestrant, including for the early disease setting, and highlights the additive value of a specifically designed multi-dose pre-surgical PD study for optimal dose selection. Table 1 Citation Format: John Robertson, Teimuraz Gogitidze, Zaza Katashvili, Juan Enrique Bargallo Rocha, Ekaterine Arkania, Iain Moppett, Kwok-Leung Cheung, Gia Nemsadze, Maxine Ajimi, Itziar Irurzun-Arana, Justin Lindemann, Teresa Klinowska, Alastair Mathewson, Christopher Morrow, Myria Nikolaou, Giorgi Dzagnidze. SERENA-3: A randomized pre-surgical window of opportunity study assessing dose and duration of camizestrant treatment in post-menopausal women with ER-positive, HER2-negative primary 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 RF01-01.

Abstract PO5-15-08: Role of next-generation sequencing testing in metastatic breast cancer

Abstract Background: With recent advances in therapy, patients with metastatic breast cancer have been living longer. Treatment has previously largely depended on the subtypes of breast cancer (ER/PR positive, HER2 positive, triple negative). In recent years, testing metastatic breast cancer samples for somatic and germline mutations has revealed additional therapeutic targets which could help patients further than standard therapeutic options. Recent evidence has demonstrated that targeted therapy may offer an advantage in overall survival in patients with metastatic breast cancer. However, data regarding the use of targeted therapy is still sparse and its overall impact on metastatic breast cancer patients needs to be further investigated. We wanted to study genomic testing in such patients and see how often it leads to new therapy recommendations beyond standard of care as we move towards the era of precision medicine. Methods: Patients who were diagnosed with metastatic breast cancer between 2015-2020 were screened and a total of 193 patients were identified. Baseline characteristics, treatment/outcome and NGS testing information was collected. Univariate two group comparisons were performed using t-tests for continuous variables, and using chi-square, or Fisher’s tests if cell counts were < 5 for categorical variables. Survival analysis for progression free survival (PFS) and overall survival (OS) were done using log rank tests. Results: Out of 193 patients, the majority (189) were female. There were 121 (62.7%) White patients, 69 (35.8%) Black patients, and 3 (1.6%) patients that were another race. 30.6 % of patients received next-generation sequencing (NGS) testing, 68.4% of patients did not, and 1% were unknown. Patients that received NGS testing were on average younger than those that did not receive NGS testing (53.24 years old vs 65.17 years old, respectively). Patients that received NGS testing were more likely to be premenopausal (p < .0001). Patients without NGS testing were more likely to die than those with NGS testing (p=.0327). There were no statistically significant differences observed in percentage of patients getting NGS testing done and whether patients were triple negative, HER2 positive with hormone receptor positive or negative, and HER2 negative with hormone receptor positive. As the year of metastatic breast cancer diagnosis advanced from 2015-2020, a high percentage of patients received NGS testing (i.e. 20% diagnosed in 2015 received NGS testing, whereas 50% diagnosed in 2020 received NGS testing). As the number of years between diagnosis and last follow-up increased, the probability of progression decreased for patients that had NGS testing done. Patients with NGS testing did better than those without NGS testing, but patients with no treatment change had the lowest probability of progression. Conclusion: On average, only 30% of patients are receiving NGS testing, however it is being done more often in recent years than ever before. There is a clear progression free survival benefit seen in patients who received NGS testing. It is interesting to note that those who did not receive any changes in treatment based on NGS testing have the lowest probability of progression, but overall survival was not different for any of the different groups studied. This could be related to the low number of patients with NGS testing in our analysis. Further studies are warranted to understand this association. Table. Summary of NGS testing data in various demographic categories There was a statistically significant difference in whether NGS testing was obtained or not and age, menopausal status and current status. There was no statistically significant difference in whether NGS testing was obtained or not and gender or race. Citation Format: Kashmira Wani, Manasi Godbole, Brigid Jacob, Kylie Springer, Vrushali Dabak. Role of next-generation sequencing testing in 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 PO5-15-08.

Abstract PO3-04-13: SUMIT-ELA: Phase 1b/2 combination of cyclin-dependent kinase 7 inhibitor (CDK7i) samuraciclib and selective estrogen receptor degrader (SERD) elacestrant in advanced hormone receptor positive (HR+) breast cancer after CDK4/6i

Abstract Background: CDK7 has 3 critical roles in cancer: enhanced transcription of oncogenes and upregulation of anti-apoptotic genes, acceleration of the cell cycle through phosphorylation of other CDKs and driving estrogen receptor (ER) resistance to hormonal therapy. Inhibition of CDK7 is therefore a potential novel anti-cancer therapeutic strategy. Samuraciclib (CT7001), a once daily oral CDK7 inhibitor has demonstrated a favorable safety profile and clinical activity in combination with fulvestrant (SERD) in patients with HR+/HER2- advanced breast cancer who have previously been treated with a CDK4/6 inhibitor [1]. Extended benefit was observed in patients with no TP53-mutation per circulating tumor DNA (ctDNA) analysis detectable at baseline. Limitations in the pharmacokinetic (PK) properties and route of administration (intramuscular only) of fulvestrant mean that oral alternatives are desirable. Recently, the EMERALD phase 3 study of the oral SERD elacestrant demonstrated a significant PFS benefit over standard of care endocrine treatment in the ER+/HER2- advanced or metastatic breast cancer population previously treated with a CDK4/6 inhibitor. [2]. Non-clinical data indicate that the underlying biology driving samuraciclib combination with endocrine therapy translates from fulvestrant to elacestrant, clinical evaluation is warranted [3]. This open-label Phase 1b dose escalation and Phase 2 dose expansion study will evaluate the safety, efficacy and pharmacokinetics of samuraciclib in combination with elacestrant. ctDNA analysis is informative for both elacestrant and samuraciclib, via ESR1-mutation status and TP53-mutation status respectively, and is an integral part of the study design. Trial Design: Eligible patients will provide written informed consent, be aged 18 years or older, have histologically or cytologically confirmed ER+/HER2- advanced or metastatic breast cancer not amenable to resection or radiotherapy of curative intent, have received an aromatase inhibitor in combination with a CDK4/6 inhibitor in either the adjuvant or advanced setting, be receiving a luteinizing hormone-releasing hormone agonist if pre/perimenopausal and have RECIST v1.1 evaluable disease. Prior SERD, mammalian target of rapamycin inhibitor (mTORi) or chemotherapy for advanced breast cancer are not permitted. The study will enrol ~48 patients. All patients will undergo baseline Guardant360 ctDNA analysis to establish their ESR-1 and TP53-mutation status. Patients will undergo RECIST v1.1 evaluation at baseline every 8-weeks until week 48, followed by every 12-weeks thereafter. Initially both samuraciclib and elacestrant will be administered once daily in a dose escalation/de-escalation approach under supervision of the study Safety Review Committee. The primary endpoint in Phase 1b is the identification of tolerable combination dose levels for both samuraciclib and elacestrant and in Phase 2 expansion to quantify the progression free survival benefit of the combination. Secondary endpoints are tolerability, clinical benefit response at 24 weeks, overall response rate, duration of response, best percent change in tumor size, pharmacokinetics and correlations between ctDNA detectable ESR1 and TP53 mutations and efficacy/safety finding in this patient population. The study opened for recruitment in June 2023.

Abstract PO4-05-10: A Carryover Effect: Antibody Drug Conjugates Constantly Provide a Substantial Improvement in Overall Survival more than in Progression-free Survival

Abstract Background: In metastatic breast cancer (MBC), progression-free survival (PFS) improvement does not always translate into overall survival (OS) benefit. Multiple treatment options after progression resulted in a long post-progression survival in MBC patients, and these would make the dissociation of PFS benefit and OS benefit. We have reported the constant correlation of PFS improvement and OS improvement in anti-HER2 containing treatment (Breast 2021; 59:211-220). The relationship between PFS and OS improvement in antibody drug conjugate has not been thoroughly examined. Methods: “Metastatic breast cancer” and “antibody drug conjugate” (ADC) were used as keywords to search for randomized clinical trials that report both PFS and OS. Hazard ratios (HR) and median survival were analyzed. Increments in PFS (delta PFS) and increments in OS (delta OS) were compared between studies. Results: A total of 8 trials were identified and summarized in table 1. The target of ADC was HER2 (N=6) or Trop2 (N=2). In DESTINY-Breast 03 trial, the control arm was another ADC (T-DM1). The control arms in all the other 7 trials were chemotherapy. The HR of PFS (range 0.28-0.66) was smaller than HR of OS (range 0.48- 0.83) in all of the trials. The median OS was not reached (NR) in 1 of the trials (DB-03) and was thus removed from the analysis for delta PFS and delta OS. In the comparison of delta PFS, the increments of median PFS fell between 1.5 and 10.9 months(m). The increments of median OS were between 1.6 and 12.7 m. All the delta OS are greater than the delta PFS in the 7 trials with available PFS and OS data. Conclusion: In MBC, ADCs targeting HER2 and Trop2 both constantly provide improvement of OS greater than PFS. Further investigation on the potential mechanism is warranted. Table 1 Citation Format: I-Chun Chen, Ching-Hung Lin, Yen-Shen Lu. A Carryover Effect: Antibody Drug Conjugates Constantly Provide a Substantial Improvement in Overall Survival more than in Progression-free Survival [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 PO4-05-10.

Abstract PO1-05-07: Circulating tumor DNA dynamics in acelERA Breast Cancer: a Phase II study of giredestrant for estrogen receptor-positive, HER2-negative, previously treated advanced breast cancer

Abstract BACKGROUND Giredestrant (GIR) is a highly potent, oral, selective estrogen receptor antagonist and degrader (SERD) that exhibits robust estrogen receptor (ER) occupancy. The Phase II, randomized, open-label acelERA Breast Cancer (BC) study (NCT04576455) assessed GIR vs physician’s choice of endocrine therapy (PCET) in second- or third-line ER-positive, HER2-negative advanced BC (ER+, HER2– aBC). The study did not reach statistical significance for the primary endpoint of investigator-assessed progression-free survival (PFS); however, the benefit of GIR was of larger magnitude among patients (pts) with ESR1-mutated tumors (ESR1m; a common cause of acquired resistance to endocrine therapy [ET]). We present an exploratory biomarker analysis of circulating tumor (ct)DNA dynamics. METHODS Pts (n = 303) were randomized 1:1 to GIR or PCET (75% of pts had fulvestrant [FUL]; 25%, an aromatase inhibitor). Partial response (PR), stable disease (SD), and progressive disease (PD) were categorized by RECIST v1.1. Plasma samples taken at Cycle 1, Day 1 (C1D1; n = 229), while on treatment (tx) at C2D1 (n = 220), and at the end of therapy (EOT; n = 155) were evaluated with the FoundationOne Liquid CDx next-generation sequencing assay. Gene mutations were defined as variants with known or likely impact on protein function. Composite tumor fraction (cTF) was defined as the total estimated tumor ctDNA content in each sample, and was only evaluable for a subset of samples (137 C1D1; 136 C2D1; 99 EOT). cTF or ESR1 mutant allele frequency (MAF) changes were calculated as a percent change from C1D1. ESR1m clonality was estimated as variant tumor fraction/estimated tumor fraction. Statistical significance was evaluated using the Mann–Whitney test. RESULTS The overall mutation landscape remained relatively unchanged with GIR tx at C2D1 or EOT, except for ESR1m prevalence, which declined from 43% at C1D1 to 26% on tx and 27% at EOT. With PCET, ESR1m prevalence decreased from 34% at C1D1 to 29% on tx, but increased to 43% by EOT. There were no concordant changes for other top mutated genes in this study, including PIK3CA, TP53, or DNMT3A. cTF decreased on tx in 38/65 (59%) and 32/59 (54%) of evaluable pts with GIR and PCET, respectively; the median change from C1D1 was –23% with GIR compared with –5% with PCET or –15% with FUL. The median change in cTF levels on tx with GIR was significantly greater in pts with a PR (–88%) vs PD (+6%, p = 0.002) or SD (–19%, p = 0.004). The degree of cTF decline on tx with GIR was significantly higher in pts with baseline ESR1m (median change –58%) vs no ESR1m detected (+5%, p = 0.012). Pts with a clonal ESR1m had higher levels of cTF decline on tx vs pts with subclonal ESR1m, suggesting cTF dynamics are a function of tumor heterogeneity. ESR1 MAF decreased on tx in 93% of pts with baseline ESR1m on GIR, vs 60% with PCET and 70% with FUL. ESR1 MAF decline on tx was significantly higher with GIR vs PCET at both C2D1 and EOT (p < 0.0001). The average ESR1 MAF decline on tx with GIR was greater in pts with a PR (–97%) vs PD (–54%, p = 0.025) or SD (–48%, p = 0.051), and all seven GIR-treated pts with a PR showed a near or total loss of ESR1 MAF by C2D1. The ESR1m variants D538G and Y537X had a significantly greater decline in MAF on tx with GIR vs PCET or FUL (p < 0.0001). CONCLUSIONS Data show that cTF and ESR1m ctDNA dynamics were associated with clinical response to GIR in ER+, HER2– aBC. ESR1 MAF decline was significantly greater with GIR vs PCET or FUL. ESR1 MAF declined to a greater degree with GIR compared with cTF, which is consistent with the larger magnitude of PFS benefit seen with GIR in pts with ESR1m tumors. The specific ESR1 variants D538G and Y537X showed greater sensitivity to GIR compared with PCET or FUL. Citation Format: Ann Collier, Aditya Bardia, Joo Hyuk Sohn, Elgene Lim, Marianna Chavez, Miguel Martín, Jorge Martinalbo, Pablo Perez-Moreno, Heather Moore. Circulating tumor DNA dynamics in acelERA Breast Cancer: a Phase II study of giredestrant for estrogen receptor-positive, HER2-negative, previously treated advanced 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 PO1-05-07.

Abstract PS04-02: BRCA testing and PARP inhibitor utilization in real-world HER2-negative metastatic breast cancer

Abstract Background: PARP inhibitors (PARPi) have demonstrated progression-free survival benefits vs. chemotherapy in patients (pts) with metastatic breast cancer (mBC) and germline BRCA mutations (gBRCAm). NCCN guidelines recommend that all pts with mBC are offered gBRCAm testing to aid in systemic treatment decisions with PARPi. Understanding real-world gBRCAm testing patterns and PARPi use would be beneficial for improving clinical outcomes of pts with gBRCAm mBC. Methods: This retrospective cohort study identified pts ≥ 18 years old with HER2-negative mBC, diagnosed from 2014 to 2022 (US Flatiron Electronic Health Record database). gBRCAm testing patterns in mBC over time were examined by BC subtype (hormone receptor-positive [HR+] or triple-negative breast cancer [TNBC]) and disease stage at diagnosis [de novo or recurrent]). Timing of gBRCAm testing and subsequent initiation of first-line or later PARPi in pts with gBRCAm HR+ and TNBC mBC was assessed in pts diagnosed after 2018 when PARPi were approved in mBC. Prevalence of gBRCAm was calculated overall and by mBC subtype. Demographic and clinical characteristics were described by gBRCAm testing and PARPi initiation (yes/no). Real-world overall survival (OS) by PARPi use since mBC diagnosis was estimated using the Kaplan-Meier method and a log-rank test. Results: Of 15,006 total pts, 4654 (31.0%) had a gBRCAm test. Compared with pts who were not tested, gBRCAm-tested pts were younger at initial mBC diagnosis (median age: 53.5 vs. 62.0 years), had a shorter median disease-free interval before mBC diagnosis (821 vs. 959 days), and were less likely to have de novo mBC (28.0% vs. 31.2%). gBRCAm testing prevalence was 6.1% in the HR+ group (n=11,945) and 8.9% in the TNBC group (n=2430). gBRCAm testing rates mostly increased from 2014 to 2022 and were lowest in HR+ tumor subtypes; < 2/3 of all pts had a gBRCAm test from 2020 onwards (Table). Most pts with recurrent mBC (HR+: 68.3%; TNBC: 76.1%) were gBRCAm tested before diagnosis, whereas pts with de novo mBC were tested at a later timepoint ( > 60 days after mBC diagnosis – HR+: 48.3%; TNBC: 38.4%). Of all pts with gBRCAm diagnosed from 2018 onwards (n=187), 44.4% initiated PARPi. A higher proportion of pts with gBRCAm in the TNBC group initiated PARPi (52.9%) than in the HR+ group (42.4%). Pts with gBRCAm in the TNBC group received PARPi earlier than pts with gBRCAm in the HR+ group (mean days from mBC diagnosis to first PARPi use: 173 and 411 days, respectively). Fewer pts with de novo mBC (35.7%) initiated PARPi than pts with recurrent mBC (50.8%). With a median follow-up of 15.3 months, pts with gBRCAm initiated on PARPi had numerically longer median OS (32.3 months [95% CI: 24.2–47.4]) than PARPi non-initiators (21.4 months [95% CI:18.4–43.5]). OS results should be regarded with caution due to the small sample size (n=187). Conclusions: Despite NCCN guideline gBRCAm-testing recommendations, < 2/3 of pts with HER2-negative mBC in our study were gBRCAm tested from 2020 onwards. gBRCAm testing was lower in pts with HR+ disease and was performed at a later timepoint for pts with de novo disease. Wider and timelier implementation of gBRCAm testing to identify pts that could benefit from PARPi is warranted. Fewer pts with gBRCAm who had HR+ tumors or de novo disease received PARPi than pts with TNBC. Our data suggest that pts who initiated PARPi had numerically longer OS than PARPi non-initiators; further research into OS trends and PARPi use in gBRCAm mBC would be of interest. Editorial acknowledgment: Medical writing assistance was provided by Leigh-Ann Booth, Ph.D. from BOLDSCIENCE Inc., funded by AstraZeneca and Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, US Legal entity responsible for the study: AstraZeneca. Funding: This study was supported by AstraZeneca and Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, US, who are codeveloping olaparib. Table. gBRCAm testing rates over time in pts with HER2-negative mBC HER2-negative mBC is defined as IHC 0, or 1-positive, or IHC2-positive/ISH-negative. *Olaparib approved in mBC; †Olaparib approved in eBC. eBC, early breast cancer; gBRCAm, germline breast cancer gene mutation; HER2, human epidermal growth factor receptor 2; HR, hormone receptor; IHC, immunohistochemistry; ISH, in situ hybridization; mBC, metastatic breast cancer; pt, patient; TNBC, triple-negative breast cancer. Citation Format: Siddhartha Yadav, Sam Hillman, Linlin Luo, Weiyan Li, Jagadeswara Earla, Xiaoqing Xu. BRCA testing and PARP inhibitor utilization in real-world HER2-negative 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 PS04-02.

Nivolumab plus chemotherapy or ipilimumab versus chemotherapy in patients with advanced esophageal squamous cell carcinoma (CheckMate 648): 29-month follow-up from a randomized, open-label, phase III trial.

First-line nivolumab plus chemotherapy and nivolumab plus ipilimumab both demonstrated significant overall survival (OS) benefit versus chemotherapy in previously untreated patients with advanced esophageal squamous cell carcinoma (ESCC) in the CheckMate 648 trial, leading to approvals of both nivolumab-containing regimens in many countries. We report longer-term follow-up data. This open-label, phase III trial (NCT03143153) enrolled adults with previously untreated, unresectable, advanced, recurrent, or metastatic ESCC. Patients were randomized 1:1:1 to nivolumab plus chemotherapy, nivolumab plus ipilimumab, or chemotherapy. Primary endpoints were OS and progression-free survival (PFS) by blinded independent central review. Hierarchical testing was performed first in patients with tumor cell programmed death ligand 1 (PD-L1) expression of ≥1% and then in the overall population. A total of 970 patients were randomly assigned. After 29 months of minimum follow-up, nivolumab plus chemotherapy continued to demonstrate improvement in OS versus chemotherapy (hazard ratio [HR] = 0.59 [95% CI: 0.46-0.76]) in patients with tumor cell PD-L1 expression of ≥1% and in the overall population (HR = 0.78 [95% CI: 0.65-0.93]) and with nivolumab plus ipilimumab versus chemotherapy (HR = 0.62 [95% CI: 0.48-0.80]) in patients with tumor cell PD-L1 expression of ≥1% and in the overall population (HR = 0.77 [95% CI: 0.65-0.92]). In patients with tumor cell PD-L1 expression of ≥1%, nivolumab plus chemotherapy demonstrated PFS benefit versus chemotherapy (HR = 0.67 [95% CI: 0.51-0.89]); PFS benefit was not observed with nivolumab plus ipilimumab versus chemotherapy (HR = 1.04 [95% CI: 0.79-1.36]). Among all treated patients (n = 936), Grade 3-4 treatment-related adverse events were reported in 151 (49%, nivolumab plus chemotherapy), 105 (32%, nivolumab plus ipilimumab), and 110 (36%, chemotherapy) patients. Nivolumab plus chemotherapy and nivolumab plus ipilimumab continued to demonstrate clinically meaningful OS benefit versus chemotherapy with no new safety signals identified with longer follow-up, further supporting use as first-line standard treatment options for patients with advanced ESCC.

Real-World Data Analysis of CDK4/6 Inhibitor Therapy-A Patient-Centric Single Center Study.

The quest to comprehend the real-world efficacy of CDK4/6 inhibitors (CDKis) in breast cancer continues, as patient responses vary significantly. This single-center retrospective study evaluated CDKi use outside the trial condition from November 2016 to May 2020. Progression-free survival (PFS), time-to-treatment failure (TTF), short-term and prolonged treatment benefit (≥4 and ≥10 months), as well as prognostic and predictive markers were assessed with Kaplan-Meier and multivariate regression analyses. Out of 86 identified patients, 58 (67.4%) had treatment failure of which 40 (46.5%) were due to progression. Median PFS and TTF were 12 and 8.5 months, respectively. A total of 57 (66.3%) and 42 (48.8%) patients experienced short-term and prolonged treatment benefit. Independent, significant predictors for PFS were progesterone receptor expression (HR: 0.88), multiple metastatic sites (HR: 2.56), and hepatic metastasis (HR: 2.01). Significant predictors for TTF were PR expression (HR: 0.86), multiple sites (HR: 3.29), adverse events (HR: 2.35), and diabetes (HR: 2.88). Aside from tumor biology and adverse events, treatment modifications like pausing and switching of CDKi were predictive for short-term (OR: 6.73) and prolonged (OR: 14.27) therapeutic benefit, respectively. These findings emphasize the importance of tailored treatment strategies, highlighting the role of PR expression, metastatic burden, and therapeutic adjustments in optimizing patient outcomes in real-world breast cancer management.

Abemaciclib plus a nonsteroidal aromatase inhibitor as initial therapy for HR+, HER2- advanced breast cancer: Final overall survival results of MONARCH 3

BackgroundIn MONARCH 2, the addition of abemaciclib to fulvestrant significantly improved both progression-free survival (PFS) and overall survival (OS) in patients with HR+, HER2- advanced breast cancer (ABC) with disease progression on prior endocrine therapy (ET). In MONARCH 3, the addition of abemaciclib to a nonsteroidal aromatase inhibitor (NSAI) as initial therapy for HR+, HER2- ABC significantly improved PFS. Here, we present the prespecified final OS results for MONARCH 3. Patients and MethodsMONARCH 3 is a randomized, double-blind, phase 3 study of abemaciclib plus NSAI (anastrozole or letrozole) versus placebo plus NSAI in postmenopausal women with HR+, HER2- ABC without prior systemic therapy in the advanced setting. The primary objective was investigator-assessed PFS; OS was a gated secondary endpoint, and chemotherapy-free survival (CFS) was an exploratory endpoint. ResultsA total of 493 women were randomized 2:1 to receive abemaciclib plus NSAI (n = 328) or placebo plus NSAI (n = 165). After a median follow-up of 8.1 years, there were 198 OS events (60.4%) in the abemaciclib arm and 116 (70.3%) in the placebo arm (hazard ratio, 0.804; 95% confidence interval [CI], 0.637-1.015; P = 0.0664, non-significant). Median OS was 66.8 versus 53.7 months for abemaciclib versus placebo. In the subgroup with visceral disease (sVD), there were 113 OS events (65.3%) in the abemaciclib arm and 65 (72.2%) in the placebo arm (hazard ratio, 0.758; 95% CI, 0.558-1.030; P = 0.0757, non-significant). Median OS was 63.7 months versus 48.8 months for abemaciclib versus placebo. The previously demonstrated PFS benefit was sustained, and CFS numerically improved with the addition of abemaciclib. No new safety signals were observed. ConclusionAbemaciclib combined with an NSAI resulted in clinically meaningful improvement in median OS (ITT: 13.1 months; sVD: 14.9 months) in patients with HR+ HER2- ABC; however, statistical significance was not reached.

Breakthrough Therapy Cancer Drugs and Indications With FDA Approval: Development Time, Innovation, Trials, Clinical Benefit, Epidemiology, and Price.

The breakthrough therapy designation (BTD) facilitates the development of drugs with a large preliminary benefit in treating serious or life-threatening diseases. This study analyzes the FDA approval, trials, benefits, unmet needs, and pricing of breakthrough and nonbreakthrough therapy cancer drugs and indications. We analyzed 355 cancer indications with FDA approval (2012-2022). Breakthrough and nonbreakthrough indications were compared regarding their FDA approval, innovativeness, clinical trials, epidemiology, and price. Data were extracted from FDA labels, the Global Burden of Disease study, and the Centers for Medicare & Medicaid Services. Hazard ratios (HRs) for overall survival (OS), progression-free survival (PFS), and relative risk (RR) of tumor response were meta-analyzed across randomized controlled trials. Objective response rates (ORRs) were meta-analyzed for single-arm trials. We identified 137 breakthrough and 218 nonbreakthrough cancer indications. The median clinical development time was 3.2 years shorter for breakthrough drugs than for nonbreakthrough drugs (5.6 vs 8.8 years; P=.002). The BTD was more frequently granted to biomarker-directed indications (46% vs 34%; P=.025) supported by smaller trials (median, 149 vs 326 patients; P<.001) of single-arm (53% vs 27%; P<.001) and phase I or II design (61% vs 31%; P<.001). Breakthrough indications offered a greater OS (HR, 0.69 vs 0.74; P=.031) and tumor response (RR, 1.48 vs 1.32; P=.006; ORR, 52% vs 40%; P=.004), but not a PFS benefit (HR, 0.53 vs 0.58; P=.212). Median improvements in OS (4.8 vs 3.2 months; P=.002) and PFS (5.4 vs 3.3 months; P=.005) but not duration of response (8.7 vs 4.7 months; P=.245) were higher for breakthrough than for nonbreakthrough indications. The BTD was more frequently granted to first-in-class drugs (42% vs 28%; P=.001) and first-in-indication treatments (43% vs 29%; P<.001). There were no differences in treatment and epidemiologic characteristics between breakthrough and nonbreakthrough drugs. Breakthrough drugs were more expensive than nonbreakthrough drugs (mean monthly price, $38,971 vs $22,591; P=.0592). The BTD expedites patient access to effective and innovative, but also expensive, new cancer drugs and indications.