IDF Events Research Articles

Invasive disease-free survival and brain metastasis rates in patients treated with neoadjuvant chemotherapy with trastuzumab and pertuzumab

Patients with HER2(+) early breast cancer (EBC) receiving neoadjuvant systemic therapy (NAST) have poorer outcomes if they have residual disease (RD). We analyzed IDFS and brain metastasis (BM) rates in patients with HER2(+) EBC treated with NAST and report the outcomes of patients with HER2(−) RD. Patients with HER2(+) EBC who received NAST between 1 Jan 2019 and 31 Jan 2022 were reviewed. IDFS was defined as the time from surgery until first occurrence of invasive breast cancer recurrence, distant recurrence, or death from any cause. The total cohort was 594 patients. pCR (ypT0/isN0) was achieved in 325(55%) and RD was seen in 269(45%) patients. In 269 patients with RD, 45(17%) did not have HER2 retesting and were excluded. In the remaining 224 patients, 143(64%) were HER2(+) and 81(36%) were HER2(−). With a median follow up of 24 months, 8 patients developed BM at initial recurrence, 4/325(1.2%) with pCR and 4/143(2.8%) with HER2(+) RD. IDFS events occurred in 22/594(3%) patients; 14/269(5%) in RD and 8/325(2%) in pCR (p = 0.04). There was no difference in IDFS between 9/143(6%) patients with HER2(+) RD or 5/81(6%) with HER2(−) RD (p = 0.10). Patients with RD had higher IDFS events than those with pCR. In those with RD, 36% lost HER2(+) status; IDFS events appeared similar in those with HER2(+) RD versus those with HER2(−) RD. The BM events seen in those with RD and pCR highlights the need for more effective therapy in NAST and adjuvant setting to minimize BM risk.

A phase III trial of adjuvant ribociclib plus endocrine therapy versus endocrine therapy alone in patients with HR-positive/HER2-negative early breast cancer: final invasive disease-free survival results from the NATALEE trial

NATALEE assessed efficacy and tolerability of 3 years of adjuvant ribociclib plus NSAI compared with a nonsteroidal aromatase inhibitor (NSAI) alone in a broad population of patients with HR+/HER2- early breast cancer, including a select group without nodal involvement. This is the final preplanned analysis of invasive disease-free survival (iDFS). Premenopausal/postmenopausal women and men were randomized 1:1 to ribociclib (n=2549; 400 mg/day, 3 weeks on/1 week off for 36 months) plus NSAI (letrozole 2.5 mg/day or anastrozole 1 mg/day for 60 months) or NSAI alone (n=2552). Men and premenopausal women also received goserelin (3.6 mg once every 28 days). Patients had anatomical stage IIA (N0 with additional risk factors or N1), IIB, or III disease. The primary endpoint was iDFS. Secondary efficacy endpoints were recurrence-free survival (RFS), distant DFS (DDFS), and overall survival (OS). This final iDFS analysis was planned after ≈500 events. At data cutoff (21 July 2023), ribociclib was stopped for 1996 patients (78.3%); 1091 (42.8%) completed 3 years of ribociclib, and ribociclib treatment was ongoing for 528 (20.7%). Median follow-up for iDFS was 33.3 months. Overall, 226 and 283 iDFS events occurred with ribociclib plus NSAI vs NSAI alone, respectively. Ribociclib plus NSAI demonstrated significant iDFS benefit over NSAI alone (Hazard Ratio 0.749, 95% Confidence Interval [CI] 0.628-0.892; P=0.0012). The 3-year iDFS rates were 90.7% (95% CI 89.3%-91.8%) vs 87.6% (95% CI 86.1%-88.9%). A consistent benefit was observed across prespecified subgroups, including stage (II/III) and nodal status (+/-). DDFS and RFS favored ribociclib plus NSAI. OS data were immature. No new safety signals were observed. With longer follow-up and most patients off ribociclib, NATALEE continues to demonstrate iDFS benefit with ribociclib plus NSAI over NSAI alone in the overall population and across key subgroups. Observed adverse events remained stable.

Adjuvant Trastuzumab Emtansine Versus Paclitaxel Plus Trastuzumab for Stage I Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer: 5-Year Results and Correlative Analyses From ATEMPT.

Long-term outcomes of patients with stage I human epidermal growth factor receptor 2 (HER2)-positive breast cancer receiving adjuvant trastuzumab emtansine (T-DM1) remain undefined, and prognostic predictors represent an unmet need. In the ATEMPT phase II trial, patients with stage I centrally confirmed HER2-positive breast cancer were randomly assigned 3:1 to adjuvant T-DM1 for 1 year or paclitaxel plus trastuzumab (TH). Coprimary objectives were to compare the incidence of clinically relevant toxicities between arms and to evaluate invasive disease-free survival (iDFS) with T-DM1. Correlative analyses included the HER2DX genomic tool, multiomic evaluations of HER2 heterogeneity, and predictors of thrombocytopenia. After a median follow-up of 5.8 years, 11 iDFS events were observed in the T-DM1 arm, consistent with a 5-year iDFS of 97.0% (95% CI, 95.2 to 98.7). At 5 years, the recurrence-free interval (RFI) was 98.3% (95% CI, 97.0 to 99.7), the overall survival was 97.8% (95% CI, 96.3 to 99.3), and the breast cancer-specific survival was 99.4% (95% CI, 98.6 to 100). Comparable iDFS was observed with T-DM1 irrespective of tumor size, hormone receptor status, centrally determined HER2 immunohistochemical score, and receipt of T-DM1 for more or less than 6 months. Although ATEMPT was not powered for this end point, the 5-year iDFS in the TH arm was 91.1%. Among patients with sufficient tissue for HER2DX testing (n = 187), 5-year outcomes significantly differed according to HER2DX risk score, with better RFI (98.1% v 81.8%, hazard ratio [HR], 0.10, P = .01) and iDFS (96.3% v 81.8%, HR, 0.20, P = .047) among patients with HER2DX low-risk versus high-risk tumors, respectively. Adjuvant T-DM1 for 1 year leads to outstanding long-term outcomes for patients with stage I HER2-positive breast cancer. A high HER2DX risk score predicted a higher risk of recurrence in ATEMPT.

Prognostic utility of ctDNA detection in the monarchE trial of adjuvant abemaciclib plus endocrine therapy (ET) in HR+, HER2-, node-positive, high-risk early breast cancer (EBC).

LBA507 Background: In monarchE (NCT03155997), 2 years of adjuvant abemaciclib + ET resulted in sustained improvement in invasive disease-free survival (IDFS; HR=0.680, 7.6% absolute benefit at 5 years) in patients (pts) with HR+, HER2-, node-positive, high-risk EBC. Here, we investigate the prognostic value of ctDNA detection and dynamics in pts from monarchE. Methods: Samples were analyzed from a selected pt subset (n=1397; abemaciclib + ET arm, n=685; ET arm, n=712), enriched for overall IDFS events compared to the total monarchE study population (IDFS event rate: 31% [433/1397] vs 18% [992/5637]). Pts had blood collected pre-study treatment (baseline) and at 3, 6, or 24 months. ctDNA detection was performed using the personalized, tumor informed Signatera ctDNA assay (Natera, Inc) and whole exome sequencing (WES) of matched primary tumor and normal required for assay design was performed. Results: Among 1397 pts, 65% (n=910) had sufficient plasma samples and WES performed, and all 910 had successful ctDNA assay testing. Among these 910 pts, the IDFS event rate was 27% (abemaciclib + ET, 23% [101/438]; ET alone, 31% [146/472]). Rates of ctDNA positivity (at baseline and any change from baseline) and associated IDFS events are shown in Table. Among pts with ctDNA positivity, 87% had an IDFS event in comparison to 15% with persistent ctDNA negative (-) status during the study. Conclusions: In a pt subset from monarchE enriched for IDFS events, ctDNA detection was relatively infrequent (<20%); however, its detection at any time during the 24 months of study therapy was adversely prognostic. As compared to pts who had remaining ctDNA positive (+), pts who had clearance of ctDNA on therapy had lower risk of IDFS events, but the event risk still remained clinically meaningful in these pts. Clinical trial information: NCT03155997 . [Table: see text]

Clinical outcomes of patients with HER2-positive microinvasive breast cancer.

544 Background: Although previous studies have reported that adjuvant trastuzumab with paclitaxel resulted in excellent survival outcomes in small, node-negative HER2-positive breast cancer, the necessity of adjuvant chemotherapy in HER2-positive microinvasive breast cancer (MIBC) remains controversial. Methods: Between January 2000 and January 2020, women with curatively resected pT1mi N0 and/or N1mi in Asan Medical Center were retrospectively identified and their survival outcomes including invasive disease-free survival (IDFS, excluding second primary cancer), distant recurrence-free survival (DRFS), and overall survival (OS) and the effect of adjuvant chemotherapy were analyzed. Results: A total of 833 patients were included. The median age was 51 years, and 51% (n = 426) were premenopausal. Pathologic nodal stage was pN0 in 96% (n = 799) and pN1mi in 0.7% (n = 6), and estrogen receptor (ER) was positive in 30% (n = 247). Adjuvant chemotherapy was administered to 18% (n = 147) of patients, of which 95% were fluorouracil-based. Six patients (0.7%) received adjuvant trastuzumab. With the median follow-up of 118.7 months, the 8-year IDFS and DRFS rates were 90.6% (95% CI, 88.4-92.7), and 97.3% (95% CI, 96.1-98.4), respectively, and the 8-year OS were 98.6% (95% CI, 97.8-99.5). IDFS did not differ by adjuvant chemotherapy, as the 8-year IDFS rates for patients who did and did not receive adjuvant chemotherapy were 91.1% (95% CI, 86.6-95.8) and 90.3% (95% CI, 87.9-92.8), respectively ( p = 0.930). The lack of differences in IDFS by chemotherapy was consistent across subgroups including pre-/postmenopausal patients, grade 1-2/3 tumors, and ER-negative diseases. Conclusions: In HER2-positive MIBC, a clinically meaningful proportion of patients experience IDFS events with long-term follow-up. The role of modern adjuvant chemotherapy regimens, as well as the role of adjuvant trastuzumab, should be further explored in this early-stage patient population.

Abstract GS01-03: Adding atezolizumab to adjuvant chemotherapy for stage II and III triple-negative breast cancer is unlikely to improve efficacy: interim analysis of the ALEXANDRA/IMpassion030 phase 3 trial

Abstract Background: Early stage triple negative breast cancer (TNBC) is associated with a high risk of distant relapse. ALEXANDRA/IMpassion030 is a global, prospective, randomized, open-label, phase 3 trial that investigated the efficacy, safety and pharmacokinetic profile of adjuvant atezolizumab plus standard anthracycline/taxane chemotherapy (arm A) versus chemotherapy alone (arm B) in early-stage TNBC. Methods: ALEXANDRA/IMpassion030 (NCT03498716) aimed to randomize (1:1) 2300 patients with operable stage II-III TNBC, confirmed by central pathology review. Patients were stratified by type of surgery (breast conserving versus mastectomy), nodal status (0 versus 1-3 versus >=4 nodes), and centrally assessed PD-L1 status (IC 0 vs >=1% ). Adjuvant chemotherapy consisted of weekly paclitaxel 80 mg/m2 for 12 weeks followed by dose dense anthracycline (epirubicin 90 mg/m2 or doxorubicin 60 mg/m2) and cyclophosphamide 600 mg/m2 for 4 doses every 2 weeks given concomitantly with atezolizumab 840 mg every 2 weeks followed by maintenance atezolizumab 1200 mg every 3 weeks until completion of 1 year of atezolizumab (Arm A) or the same chemotherapy regimen (T-EC/AC) alone (Arm B). The primary endpoint was invasive disease-free survival (iDFS); secondary endpoints included, iDFS in the PD-L1 positive and lymph node-positive subpopulations, overall survival, safety, patient functioning and health related quality of life (HRQoL). On the 14th of November 2022, following an IDMC recommendation, the study accrual was temporarily stopped. In February 2023, the protocol was amended in order for the IDMC to perform an early interim analysis of efficacy and futility, at approximately 62% of the planned (390) iDFS events. The futility boundary was set to a Hazard Ratio (HR) > 1. Results: The IDMC recommendations of 15th March 2023 reported that the primary endpoint crossed the futility boundary, accrual to the study was permanently stopped and the experimental treatment was discontinued. Between August 2018 and November 2022, the study enrolled 2199 patients, with 1101 randomised to the atezolizumab arm (A) and 1098 to the control arm (B). At a median follow-up of 25.3 months, 239 (10.9%) iDFS events were observed in the 2199 enrolled patients; 127 versus 112 iDFS events were observed (61.3% of 390) in the A versus B arms respectively, HR 1.12, (95% confidence interval, CI, 0.87, 1.45). In the PD-L1 positive subgroup, (1567/2199 patients, 71.3%), 77 versus 73 iDFS events were observed in the A versus B arms respectively, HR 1.03, (95% CI 0.75, 1.42). Among patients with lymph node positive tumors (1066/2199 patients, 48.5%), 86 versus 66 iDFS events were observed in the A versus B arm respectively, HR 1.41, (95% CI 1.02, 1.96). Incidence of adverse events grade >=3 was 58.01% versus 48.15% in the A versus B arms, including death in 1.01% (11) and 0.55% (6) of patients, respectively. Conclusions: Crossing the pre-specified futility boundary of HR > 1 provides evidence that adjuvant atezolizumab is very unlikely to improve invasive disease-free survival when added to adjuvant anthracycline and taxane based chemotherapy in patients with stage II-III triple-negative breast cancer. With longer treatment exposure in the atezolizumab arm (A), adverse events were more frequent but consistent with the atezolizumab safety profile. No new or unexpected safety issue was identified. Citation Format: Michail Ignatiadis, Andrew Bailey, Heather McArthur, Sarra El-Abed, Evandro de Azambuja, Otto Metzger, Steve Chui, Max Dieterich, Thomas Perretti, Guenther Steger, Jacek Jassem, Soo Chin Lee, Michaela Higgins, José Zarbá, Marcus Schmidt, Henry Gomez, Angel Guerrero-Zotano, Luca Moscetti, Joanne Win Yang Chiu, Carter DuFrane, Vanessa Honvault, Rosa Altarcheh, Luciana Molinero, Andrew Ellingson, Elisabetta Munzone, Noa Efrat Ben-Baruch, Emilio Bajetta, Shinji Ohno, Seock-Ah Im, Gustavo Werutsky, Einav Gal-Yam, Xavier Gonzalez-Farré, Ling-Ming Tseng, William Jacot, Oleg Gluz, Zhimin Shao, Yaroslav Shparyk, Ivan Sinielnikov, Zimina Anastasia, Aleksandr Vasiliev, Esther Shearer-Kang, Eric Winer, Diogo Martins-Branco, Shona Fielding, David Cameron, Giuseppe Viale, Shigehira Saji, Richard Gelber, Martine Piccart. Adding atezolizumab to adjuvant chemotherapy for stage II and III triple-negative breast cancer is unlikely to improve efficacy: interim analysis of the ALEXANDRA/IMpassion030 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 GS01-03.

Abstract GS03-03: Ribociclib (RIB) + nonsteroidal aromatase inhibitor (NSAI) as adjuvant treatment in patients with HR+/HER2− early breast cancer: final invasive disease–free survival (iDFS) analysis from the NATALEE trial

Abstract Background: Interim results from the phase 3 NATALEE trial demonstrated that adding RIB to standard-of-care adjuvant NSAI had a statistically significant iDFS benefit in patients with stage II and III HR+/HER2− early breast cancer at risk of recurrence, including those with node-negative disease (Slamon et al, ASCO 2023). We present the final protocol-specified analysis of the primary endpoint of iDFS. Methods: A total of 5101 pre-/postmenopausal women and men underwent 1:1 randomization to receive RIB (400 mg/day; 3 weeks on/1 week off for 36 months) + NSAI (letrozole 2.5 mg/day or anastrozole 1 mg/day for ≥60 months) or NSAI alone. Men and premenopausal women received goserelin (3.6 mg once every 28 days). Patients were required to have anatomic stage IIA (either N0 with additional risk factors or N1), IIB, or III breast cancer per the AJCC (8th edition). Patients remained on trial as long as they were continuing on NSAI (≤5 years), regardless of RIB discontinuation. The primary endpoint was iDFS according to STEEP v1.0 criteria, and the secondary efficacy endpoints were recurrence-free survival (RFS), distant disease–free survival (DDFS), and overall survival (OS). This final analysis was planned after approximately 500 iDFS events. iDFS was evaluated by the Kaplan-Meier method, and statistical comparison was made by a stratified log-rank test. P values were not corrected for multiple comparisons. Results: At the data cutoff (July 21, 2023), among the 2549 patients in the RIB + NSAI arm, 1091 (42.8%) completed 3 years of RIB treatment, and 905 (35.5%) discontinued RIB or RIB + NSAI early and 528 patients (20.7%) remained on RIB. 1748 patients (68.5%) remain on treatment in the NSAI arm. Median follow-up for iDFS was 33.3 months, an additional 5.6 months from the previous interim analysis. A total of 509 iDFS events were observed, 226 (8.9%) in the RIB + NSAI arm and 283 (11.1%) in the NSAI alone arm. RIB + NSAI demonstrated a significant iDFS benefit over NSAI alone (HR, 0.749; 95% CI, 0.628-0.892; P=.0006). The 3-year iDFS rates were 90.7% (95% CI, 89.3%-91.8%) vs 87.6% (95% CI, 86.1%-88.9%). A consistent benefit was observed across patient subgroups, including those with node-negative, stage II, or stage III disease (Table). Secondary endpoints of DDFS and RFS favored RIB + NSAI over NSAI alone (Table). OS data were immature, with 84 (3.3%) and 88 (3.4%) total events in the RIB + NSAI and NSAI alone arms, respectively. No new safety signals were observed since the prior interim analysis. Discontinuation of RIB due to adverse events was observed in 19.5% of patients (a <1% increase from the prior interim analysis). Conclusions: With a substantial proportion of patients completing 3 years of RIB treatment, NATALEE continues to demonstrate a significant iDFS improvement with RIB + NSAI over NSAI alone. Efficacy results confirm continued improvement in benefit across subgroups, including stage II disease. Safety findings support the manageable toxicity profile of RIB at the 400-mg starting dose in early breast cancer. Table. Citation Format: Gabriel Hortobagyi, Daniil Stroyakovsky, Denise Yardley, Chiun-Shen Huang, Peter A. Fasching, John Crown, Aditya Bardia, Stephen Chia, Seock-Ah Im, Miguel Martín, Sherene Loi, Binghe Xu, Sara Hurvitz, Carlos Barrios, Michael Untch, Rebecca Moroose, Frances Visco, Federico Parnizari, Farhat Ghaznawi, Zheng Li, Sorcha Waters, Arunava Chakravartty, Dennis Slamon. Ribociclib (RIB) + nonsteroidal aromatase inhibitor (NSAI) as adjuvant treatment in patients with HR+/HER2− early breast cancer: final invasive disease–free survival (iDFS) analysis from the NATALEE 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 GS03-03.

3-year invasive disease-free survival (iDFS) of the strategy-based, randomized phase II PHERGain trial evaluating chemotherapy (CT) de-escalation in human epidermal growth factor receptor 2-positive (HER2[+]) early breast cancer (EBC).

LBA506 Background: PHERGain is assessing the feasibility of a CT-free treatment based on a dual HER2 blockade with trastuzumab and pertuzumab (HP) in patients (pts) with HER2[+] EBC using a PET-based, pathologic complete response (pCR)-adapted strategy. In an earlier analysis of this study, a total of 227 (79.7%) of 285 pts included in group B were PET-responder (RX), of whom 86 of 227 (37.9%, 95% CI, 31.6 to 44.5; p<0.0001) achieved a pCR, reaching the first primary endpoint (Perez-Garcia JM, Lancet Oncol 2021). Methods: Details of the trial design and study population have been previously reported. Here, we present the results of the second primary endpoint, 3-year iDFS, among pts included in group B who underwent surgery based on an intent-to-treat (ITT) analysis. In brief, group B included centrally-confirmed, stage I-IIIA, HER2[+] EBC pts that were initially treated with HP (± endocrine therapy), introducing CT in pts without PET response after two treatment cycles and/or pCR. The binomial design tested the null hypothesis that the true 3-year iDFS rate was ≤89.0% against the alternative that the 3-year iDFS was >95%. We estimated that enrolling 284 pts in group B would provide 80% power at a nominal level of one-sided α of 0.025, assuming a 25% dropout rate. Results: Between June 26, 2017 and April 24, 2019, 356 pts were randomly assigned (71 pts in group A and 285 pts in group B) and 63 (89.0%) and 267 (93.7%) pts proceeded to surgery in groups A and B, respectively. In group B, the 3-year iDFS rate for the ITT population was 95.4% (95% CI, 92.8 to 98), meeting the second primary endpoint (p<0.001). After a median follow-up of 43.3 months (range, 2.4-63.0), a total of 12 iDFS events were reported, including eight distant recurrences (3.0%), three locoregional ipsilateral recurrences (1.1%), and one non-related death (0.4%). Among group B/PET-RX pts with pCR that did not receive CT as part of study treatment (n = 86), only one patient had an invasive event (locoregional ipsilateral recurrence) for a 3-year iDFS rate of 98.8% (95% CI, 96.3 to 100.0). Treatment-related adverse events (AEs) and serious adverse events (SAEs) were higher in pts allocated to group A than to group B (grade ≥3, 61.8% vs. 32.9% [p<0.001]; SAEs, 27.9% vs. 13.8% [p=0.01]). Group B/PET-RX pts with pCR presented the lowest incidence of treatment-related grade ≥3 AEs (1.2%) without any SAEs. No treatment-related deaths were reported. Conclusions: Among HER2[+] EBC pts, a PET-based, pCR-adapted strategy was associated with a substantial 3-year iDFS. These results appear comparable to those reported in several studies for the combination of neoadjuvant CT and dual HER2 blockade. This strategy identifies about a third of HER2[+] EBC pts who may safely omit CT with significantly reduced toxicity. Clinical trial information: NCT5732164 .

Ribociclib and endocrine therapy as adjuvant treatment in patients with HR+/HER2- early breast cancer: Primary results from the phase III NATALEE trial.

LBA500 Background: RIB + ET has demonstrated significant survival benefits in pre- and postmenopausal pts with HR+/HER2− metastatic BC. To investigate whether RIB + ET also improves outcomes in early BC (EBC), the Phase III NATALEE trial (NCT03701334) evaluated adjuvant RIB + ET in a broad population of pts with stage II or III HR+/HER2− EBC at risk for recurrence, including pts with no nodal involvement (N0). As extended duration of tx is crucial to prolong cell cycle arrest and drive more tumor cells into senescence or death, a 3-y duration of RIB tx at a dose of 400 mg was chosen to improve tolerability while maintaining efficacy. Results from a prespecified interim analysis of invasive disease–free survival (iDFS; primary endpoint) are presented. Methods: Men and pre- or postmenopausal women were randomized 1:1 to RIB (400 mg/day; 3 wk on/1 wk off for 3 y) + ET (letrozole 2.5 mg/day or anastrozole 1 mg/day, for ≥ 5 y) or ET alone. Men and premenopausal women also received goserelin. Eligible pts had an ECOG PS of 0-1 and BC anatomic stage IIA (either N0 with additional risk factors or 1-3 axillary lymph nodes [N1]), stage IIB, or stage III per AJCC (8th ed); prior (neo)adjuvant ET was allowed if initiated ≤ 12 mo before randomization. Stratification factors were menopausal status, disease stage, prior (neo)adjuvant chemotherapy, and geographic region. This prespecified interim analysis of iDFS, defined per STEEP criteria, was planned after ≈ 425 iDFS events (≈ 85% of planned total events). iDFS was evaluated by Kaplan-Meier methods, and statistical comparison was made by a stratified log-rank test, with a protocol-defined Lan-DeMets (O'Brien-Flemming) stopping boundary of a 1-sided P < .0128 for superior efficacy. Results: From 10 Jan 2019 to 20 April 2021, 5101 pts were randomized (RIB+ET, n = 2549; ET alone, n = 2552). As of the data cutoff (11 Jan 2023), median follow-up was 34 mo (min, 21 mo). 3- and 2-y RIB tx was completed by 515 pts (20.2%) and 1449 pts (56.8%), respectively; 3810 (74.7%) remained on study tx (RIB+ET, n = 1984; ET alone, n = 1826). iDFS was evaluated after 426 events (RIB + ET, n = 189; ET alone, n = 237). RIB + ET demonstrated significantly longer iDFS than ET alone (HR, 0.748; 95% CI, 0.618-0.906; P = .0014); 3-y iDFS rates were 90.4% vs 87.1%. iDFS benefit was generally consistent across stratification factors and other subgroups. Secondary endpoints of overall survival, recurrence-free survival, and distant disease–free survival consistently favored RIB. RIB at 400 mg had a favorable safety profile with no new signals. Conclusions: Ribociclib added to standard-of-care ET demonstrated a statistically significant, clinically meaningful improvement in iDFS with a well-tolerated safety profile. The NATALEE results support ribociclib + ET as the treatment of choice in a broad population of pts with stage II or III HR+/HER2− EBC, including pts with N0 disease. Clinical trial information: NCT03701334 .

Real-world outcomes with adjuvant nonsteroidal aromatase inhibitors (NSAIs) vs tamoxifen (TAM) in patients with hormone receptor−positive/human epidermal growth factor receptor 2−negative (HR+/HER2−) early breast cancer (EBC): A US database analysis.

542 Background: Randomized controlled trial (RCT) meta-analysis data have shown a significantly greater disease-free survival (DFS) benefit with aromatase inhibitors than TAM in patients with HR+/HER2− EBC. Here we compare real-world outcomes in patients with HR+/HER2− EBC who received adjuvant endocrine therapy (ET) with NSAIs or TAM. Methods: This was a retrospective analysis of ConcertAI’s deidentified electronic medical records data set of patients treated at US academic and community oncology clinics from January 1, 1995 to April 30, 2021. The cohort included patients with stage II-III (if IIIB or IIIC, confirmation was required on residual tumor status) HR+/HER2− EBC who underwent surgery and initiated adjuvant ET (excluding those who switched classes of ET); ovarian function suppression (OFS) was permitted. Menopausal status was determined using age (≥ 50 years) as a proxy for undocumented status. Invasive DFS (IDFS; risk of disease recurrence, death, or second primary tumor), distant DFS (DDFS; risk of distant recurrence, death, or second primary tumor), and overall survival (OS; risk of death) were assessed and defined as the time interval between start of ET and first event. Multivariate Cox regression analyses were performed, adjusting for age, stage, Charlson Comorbidity Index, and prior adjuvant or neoadjuvant chemotherapy for the ET cohort. Results: Of the total 3133 patients analyzed, 2507 were included in this analysis (NSAI ± OFS, n = 1854; TAM ± OFS, n = 653). Among these patients, the median (range) age was 59.5 (22.8-86.6) years, 25.4% were premenopausal, and 56.2% had tumor node involvement. The mean (SD) time to ET discontinuation was 46.2 (35.9) months overall and was similar between the NSAI and TAM cohorts. Reasons for ET discontinuation were undocumented or missing from the database for 76.8% of patients. Multivariate Cox regression analyses suggested a significant risk reduction with NSAIs vs TAM, with a 17% reduction in risk of an IDFS event (hazard ratio [HR], 0.83 [95% CI, 0.69-0.98]) and an 18% reduction in risk of a DDFS event (HR, 0.82 [95% CI, 0.69-0.98]). Although there were few events, OS analysis suggested a numerical trend favoring NSAIs over TAM, with a 12% reduction in risk of death (HR, 0.88 [95% CI, 0.69-1.13]). Conclusions: This real-world data analysis revealed a reduction in risk of IDFS and DDFS events with adjuvant NSAIs vs TAM in patients with HR+/HER2− EBC. Collectively, RCT and real-world data demonstrate greater benefit with adjuvant NSAIs vs TAM with respect to risk of recurrence in this patient population.

18P A translational project of the WSG-ADAPT-TN trial demonstrates immunomodulatory and anti-viral defense gene networks predicting pathological complete response (pCR) and survival after de-escalated neoadjuvant chemotherapy (NACT) in early triple-negative breast cancer (eTNBC)

NACT is the standard treatment for eTNBC, yet, molecular phenotypes driving chemotherapy sensitivity are poorly understood. Whole transcriptome profiling of baseline tumor biopsies from the neoadjuvant WSG-ADAPT-TN phase II trial (NCT01815242) was performed to identify gene networks predictive and prognostic for pCR and survival. Patients with cT1c-cT4c, cN+, centrally confirmed eTNBC were randomized to 12 weeks of nab-paclitaxel+gemcitabine (Arm A; n=182) or nab-paclitaxel+carboplatin (Arm B; n=154). The primary endpoint was pCR (ypT0/is, ypN0), secondary endpoints included survival and translational research. AmpliSeq RNA sequencing allowing simultaneous analysis of the expression of >20,000 genes was performed in 137 patients (Arm A/B: n=72/65). Differentially expressed genes were then evaluated in training (n=67) and validation (n=68) sets and two polygenic scores (PS) with a high diagnostic performance for prediction of pCR (PS:pCR) and invasive disease-free survival (PS:iDFS) were found. 49/135 (36.3%) patients had pCR; 30 iDFS events occurred during 60-month median follow-up. Genes and networks associated with immune recruitment, endogenous retroviral transcription, and viral defense were strongly associated with pCR and iDFS. PS:pCR achieved a high diagnostic accuracy (ROC AUC: 83%). In multivariate analysis (validation set) adjusted for clinical factors, pCR was associated with PS:pCR (OR 7.24; 95%CI 2.05, 25.58; p=0.002). Addition of PS:pCR to clinical factors increased ROC AUC for pCR from 0.707 to 0.887. iDFS was associated with PS:iDFS (HR 2.06; 95%CI 1.01, 4.20; p=0.046). Polygenic scores based on immunomodulatory and anti-viral defense gene networks may have utility in predicting pCR and survival, and could represent an opportunity for selecting patients for de-escalated NACT in eTNBC. This transcriptome network analysis also identifies potential new targets for personalized medicine approaches for patients without response to chemotherapy.

Abstract PD18-02: Adjuvant Paclitaxel and Trastuzumab Trial (APT) for Node-Negative, Human Epidermal Growth Factor Receptor 2–Positive (HER2+) Breast Cancer: final 10-year analysis

Abstract Background: The APT trial evaluated the activity of adjuvant paclitaxel and trastuzumab (TH) among patients with small, node negative HER2+ breast cancer. This regimen showed a 7-year invasive disease-free survival (iDFS) of 93%, a recurrence-free interval (RFI) of 97.5% with only four (1.0%) distant recurrences, and a 7-year overall survival (OS) of 95%. In this end-of-study analysis, we report the survival outcomes at 10 years and assess the role of HER2DX testing in predicting long-term outcomes with adjuvant TH. Methods: APT was a single-arm multicenter investigator-initiated phase II study in which patients with HER2+ breast cancer with tumors ≤3 cm and negative nodes (one single micrometastatic node allowed) received IV weekly paclitaxel (80 mg/m2) with IV weekly trastuzumab for 12 weeks, followed by IV trastuzumab for 9 months. The primary endpoint was 3-year iDFS. Here we report 10-year iDFS, RFI, breast cancer–specific survival (BCSS) and OS. In an exploratory analysis, the risk of recurrence was evaluated with the HER2DX genomic assay. Results: A total of 410 patients were enrolled from October 2007 to September 2010, of which 406 started the study treatment and were included in the intent to treat analysis. Median age at enrollment was 55 years (range, 24 to 85 years), and most patients (67%) had hormone receptor (HR)-positive disease. Fifty percent of patients had tumors 1.0 cm or smaller and only 9% of patients had tumors between 2 cm to 3 cm. Mean tumor size was 1.1 cm. After a median follow-up of 10.2 years (122 months), 36 iDFS events were observed, consistent with a 10-year iDFS of 89.7% (95% CI, 86.3%-93.1%). Ten-year iDFS was 90.2% (95% CI, 86.3%-94.3%) and 88.5% (95% CI, 82.4%-95.1%) for patients with HR-positive and HR-negative tumors at baseline, respectively. 10-year RFI was 96.8% (95% CI, 95.0%-98.7%), 10-year OS was 94.2% (95% CI, 91.6%-96.8%) and 10-year BCSS was 99.1% (95% CI, 98.1%-100.0%). Of the iDFS events observed in the trial, 6 were non-breast cancer related deaths and 9 were contralateral tumors, all but one locally found to be HER2-negative upon biopsy (Table 1). Among patients experiencing an iDFS event, 7 patients (1.7%) had distant recurrences, including 1 with a T2 tumor, 3 with a T1c tumor and 3 with a T1b tumor. At baseline, 6 of them had HR-positive disease, 1 had HR-negative disease, and 6 had high-grade disease. Upon biopsy of metastatic lesions, 5 of the 7 distant recurrences were locally found to be HER2+, 1 was HER2-negative and 1 had unknown HER2 status. HER2DX testing was conducted on available baseline archival tumor tissue and analyses of patients’ survival outcomes based on the HER2DX score will be presented. Conclusion: After 10 years of follow-up, adjuvant TH confirmed excellent long-term outcomes for small, node-negative HER2+ breast cancer, with a 10-year RFI of 96.8% and a 10-year BCSS of 99.1%. Table 1: iDFS events with adjuvant paclitaxel plus trastuzumab after 10.2 years of follow up Citation Format: Sara Tolaney, Paolo Tarantino, Noah Graham, Nabihah Tayob, Chau T Dang, Denise Yardley, Beverly Moy, Paul K. Marcom, Kathy S. Albain, Hope Rugo, Matthew Ellis, Iuliana Shapira, Antonio C. Wolff, Lisa Carey, Romualdo Barroso-Sousa, Michelle K. DeMeo, Molly K. DiLullo, Ann Partridge, Adrienne Waks, Clifford Hudis, Ian Krop, Harold Burstein, Aleix Prat, Eric Winer. Adjuvant Paclitaxel and Trastuzumab Trial (APT) for Node-Negative, Human Epidermal Growth Factor Receptor 2–Positive (HER2+) Breast Cancer: final 10-year analysis [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD18-02.

Abstract PD18-01: Adjuvant Trastuzumab Emtansine Versus Paclitaxel plus Trastuzumab for Stage I HER2+ Breast Cancer: 5-year results and correlative analyses from ATEMPT (TBCRC033)

Abstract Background: The ATEMPT trial primary analysis found that one year of adjuvant trastuzumab emtansine (T-DM1) achieved a 3-year iDFS of 97.8% for patients with stage I HER2+ breast cancer, but was not associated with fewer clinically relevant toxicities (CRTs) compared with paclitaxel and trastuzumab (TH). In this end-of-study analysis, we report 5-year survival outcomes and correlative analyses from the trial. Methods: Patients with stage I centrally confirmed HER2+ breast cancer were randomly assigned 3:1 to adjuvant T-DM1 for one year or TH and received T-DM1 3.6 mg/kg IV every 3 weeks for 17 cycles or paclitaxel 80 mg/m2 IV with weekly trastuzumab IV followed by trastuzumab for 9 months. The co-primary objectives were to compare the incidence of CRTs between the 2 arms and to evaluate iDFS in patients receiving T-DM1. To investigate proteomic correlates of recurrence, spatial proteomic analyses were performed on samples from 13 patients experiencing iDFS events (cases) and 24 matched controls using the NanoString GeoMx Digital Spatial Profiler. The impact of HER2 heterogeneity on outcomes was investigated among 17 cases and 51 matched controls by fluorescence in-situ hybridization (FISH). HER2 genetic heterogeneity was assessed by scrutinizing the whole tumor area and defined as the occurrence of HER2 gene amplification in >5% but < 50% invasive tumor cells. The risk of recurrence was evaluated centrally with the HER2DX genomic assay from 225 primary tumor samples. Germline whole genome sequencing (WGS) was conducted among 55 patients experiencing T-DM1-induced thrombocytopenia and/or bleeding and 55 matched controls to identify genomic correlates for this side effect. Results: A total of 497 patients who initiated protocol therapy were included in this analysis (383 T-DM1 and 114 TH). After a median follow up 5.8 years, among patients receiving T-DM1 there were a total of 11 iDFS events, with 3 distant recurrences. The 5-year iDFS for T-DM1 was 97.0% (95% CI, 95.3-98.8%), the 5-year recurrence-free interval (RFI) was 98.6% (95% CI: 97.4-99.8%) and the 5-year overall survival (OS) for T-DM1 was 97.8 % (95% CI, 96.3-99.3%). Although the study was not powered to evaluate the efficacy of TH, among the 114 patients receiving TH, a total of 9 iDFS events were observed, including 2 distant events; the 5-year iDFS with TH was 91.3% (95% CI: 86.0-96.9%), 5-year RFI was 93.3% (95% CI: 88.6-98.2%) and 5-year OS was 97.9% (95% CI: 95.2-100%). A total of 56 samples were evaluable for heterogeneity analyses, among which 14% (n=8) harbored HER2 genetic heterogeneity. Spatial proteomic analyses found that NF1 (adjusted p=0.72 × 10-6) and CTLA-4 (adjusted p=0.15 × 10-3) were significantly upregulated in primary samples from cases, while cleaved caspase 9, CD25, GITR, ICOS, p53 and PD-L2 were significantly upregulated in controls (all with adjusted p< 0.05). Germline WGS found that the top gene associations with thrombocytopenia and thrombocytopenia or bleeding were ALMS1 (p=0,19 × 10-3) and APBA3 (p=0,23 × 10-3), respectively, although none reaching the threshold for genome wide significance. rs62143195 and rs114169776 were the top single nucleotide polymorphisms associated with thrombocytopenia and thrombocytopenia or bleeding, respectively. Data on the impact of HER2 heterogeneity and of HER2DX score on survival outcomes will be presented. Conclusion: With longer follow-up, adjuvant T-DM1 confirmed outstanding long-term outcomes among patients with stage I HER2+ breast cancer, demonstrating a 5-year RFI of 98.6%. Spatial proteomic analyses identified a potential association between NF1 and CTLA-4 expression with recurrence. Details on the impact of HER2 heterogeneity and HER2DX assay on prognosis will be presented. Citation Format: Paolo Tarantino, Nabihah Tayob, Chau T Dang, Denise Yardley, Steven J. Isakoff, Vicente Valero, Meredith Faggen, Therese Mulvey, Ron Bose, Douglas Weckstein, Antonio C. Wolff, Katherine Reeder-Hayes, Hope Rugo, Bhuvaneswari Ramaswamy, Dan Zuckerman, Lowell Hart, Vijayakrishna K. Gadi, Michael Constantine, Kit Cheng, Audrey Merrill Garrett, Paul K. Marcom, Kathy S. Albain, Patricia DeFusco, Nadine Tung, Blair Ardman, Rita Nanda, Rachel C. Jankowitz, Mothaffar Rimawi, Vandana Abramson, Paula R. Pohlmann, Catherine Van Poznak, Andres Forero-Torres, Minetta C. Liu, Kathryn Ruddy, Yue Zheng, Romualdo Barroso-Sousa, Adrienne Waks, Michelle K. DeMeo, Molly K. DiLullo, Giuseppe Curigliano, Harold Burstein, Ann Partridge, Eric Winer, Giuseppe Viale, Winnie Hui, Elizabeth A. Mittendorf, Bryan P. Schneider, Aleix Prat, Ian Krop, Sara Tolaney. Adjuvant Trastuzumab Emtansine Versus Paclitaxel plus Trastuzumab for Stage I HER2+ Breast Cancer: 5-year results and correlative analyses from ATEMPT (TBCRC033) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD18-01.

Abstract GS5-02: Neoadjuvant paclitaxel/olaparib in comparison to paclitaxel/carboplatinum in patients with HER2-negative breast cancer and homologous recombination deficiency – long-term survival of the GeparOLA study

Abstract Background: The GeparOLA study was designed to evaluate the efficacy and safety of the combination of paclitaxel (P) plus olaparib (O) as part of neoadjuvant chemotherapy (NACT) in patients with human epidermal growth factor receptor 2 (HER2)-negative, either hormone receptor (HR)-positive or HR-negative and homologous recombination deficiency (HRD) defined as having a g/tBRCA mutation and/or a high HRD score. Primary analysis showed a pCR rate of 55.1% (90% CI 44.5%-65.3%) with PO and 48.6% (90% CI 34.3%-63.2%) with P plus carboplatinum (Cb). The PO combination could not exclude a pCR rate of ≤55% in the PO arm but was significantly better tolerated. Analysis on the stratified subgroups showed higher pCR rates with PO in the cohorts of patients < 40 years and HR-positive tumors (Fasching Ann Oncol 2020). Here, we report long-term data. Methods: GeparOLA (NCT02789332) was a non-comparative, multicenter, prospective, randomized, open-label, phase II trial. Patients with primary HER2-negative breast cancer, HRD and indication for chemotherapy (cT2-cT4a-d or cT1c and cN+ or cT1c and pNSLN+ or cT1c and TNBC or cT1c and Ki-67 >20%) were randomly assigned to receive either P 80 mg/m2 weekly plus O 100 mg twice daily for 12 weeks or P plus Cb area under the curve 2 (AUC2) weekly for 12 weeks, both followed by four cycles of either 2-weekly or 3-weekly epirubicin 90 mg/m2 plus cyclophosphamide 600 mg/m2. Primary endpoint was pCR (ypT0/is ypN0) rate after NACT with PO followed by EC. Long-term efficacy endpoints included invasive disease-free survival (iDFS), distant disease-free survival (DDFS) and overall survival (OS). The time-to-event endpoints analysis is planned with median follow-up of at least 4 years and a follow-up completeness of at least 80%. Results: Between September 2016 and July 2018, 274 patients were screened, of whom 107 were randomized and 106 (PO N=69; PCb N=37) started treatment. The median age was 47.0 years (range 25.0-71.0); 32 patients were aged < 40 years; 36.2% of patients had cT1 tumors and 31.8% were cN-positive; the majority (86.8%) had grade 3 tumors and a Ki-67>20% (89.6%). Seventy-seven patients (72.6%) had TNBC. After a median follow-up of 49.8 months (range 0.1-69.1), 18 (15 in PO; 3 in PCb) iDFS events and 7 (6 in PO; 1 in PCb) deaths were reported. The 4-year survival rates are shown in the table below. iDFS (HR PO to PCb=2.86 [95%CI 0.83-9.9], log-rank p=0.081), DDFS (HR =3.03 [95%CI 0.67-13.67], log-rank p=0.129), and OS (HR=3.27 [95%CI 0.39-27.2], log-rank p=0.244) tended to be inferior with olaparib. Patients without g/tBRCA mutation seem to benefit from the use of carboplatinum (7/30 iDFS/DDFS events in PO; 0/16 in PCb, log-rank p=0.037, HR n.a.). Conclusions: In patients with HER2-negative and HRD breast cancer the use of olaparib instead of carboplatinum although showing comparable pCR rates, tended to result in an overall inferior outcome. This was mainly driven by the patients without a g/tBRCA mutation. In patients with a g/t BRCA mutation no difference between olaparib and carboplatinum was seen. Key words: Olaparib, HER2-negative breast cancer, HRD, survival Funding: The study was financially supported by AstraZeneca Citation Format: Peter A. Fasching, Sabine Schmatloch, Jan Hauke, Julia Rey, Christian Jackisch, Peter Klare, Theresa Link, Claus Hanusch, Jens Huober, Andrea Stefek, Sabine Seiler, Wolfgang D. Schmitt, Christoph Uleer, Gabriele Doering, Kerstin Rhiem, Andreas Schneeweiss, Carsten Denkert, Rita K. Schmutzler, Eric Hahnen, Michael Untch, Valentina Nekljudova, Jens-Uwe Blohmer, Sibylle Loibl. Neoadjuvant paclitaxel/olaparib in comparison to paclitaxel/carboplatinum in patients with HER2-negative breast cancer and homologous recombination deficiency – long-term survival of the GeparOLA study [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS5-02.

Abstract P4-06-13: Neoadjuvant paclitaxel/olaparib in comparison to paclitaxel/carboplatinum in patients with HER2-negative breast cancer and homologous recombination deficiency – long-term survival of the GeparOLA study

Abstract Background: The GeparOLA study was designed to evaluate the efficacy and safety of the combination of paclitaxel (P) plus olaparib (O) as part of neoadjuvant chemotherapy (NACT) in patients with human epidermal growth factor receptor 2 (HER2)-negative, either hormone receptor (HR)-positive or HR-negative and homologous recombination deficiency (HRD) defined as having a g/tBRCA mutation and/or a high HRD score. Primary analysis showed a pCR rate of 55.1% (90% CI 44.5%-65.3%) with PO and 48.6% (90% CI 34.3%-63.2%) with P plus carboplatinum (Cb). The PO combination could not exclude a pCR rate of ≤55% in the PO arm but was significantly better tolerated. Analysis on the stratified subgroups showed higher pCR rates with PO in the cohorts of patients < 40 years and HR-positive tumors (Fasching Ann Oncol 2020). Here, we report long-term data. Methods: GeparOLA (NCT02789332) was a non-comparative, multicenter, prospective, randomized, open-label, phase II trial. Patients with primary HER2-negative breast cancer, HRD and indication for chemotherapy (cT2-cT4a-d or cT1c and cN+ or cT1c and pNSLN+ or cT1c and TNBC or cT1c and Ki-67 >20%) were randomly assigned to receive either P 80 mg/m2 weekly plus O 100 mg twice daily for 12 weeks or P plus Cb area under the curve 2 (AUC2) weekly for 12 weeks, both followed by four cycles of either 2-weekly or 3-weekly epirubicin 90 mg/m2 plus cyclophosphamide 600 mg/m2. Primary endpoint was pCR (ypT0/is ypN0) rate after NACT with PO followed by EC. Long-term efficacy endpoints included invasive disease-free survival (iDFS), distant disease-free survival (DDFS) and overall survival (OS). The time-to-event endpoints analysis is planned with median follow-up of at least 4 years and a follow-up completeness of at least 80%. Results: Between September 2016 and July 2018, 274 patients were screened, of whom 107 were randomized and 106 (PO N=69; PCb N=37) started treatment. The median age was 47.0 years (range 25.0-71.0); 32 patients were aged < 40 years; 36.2% of patients had cT1 tumors and 31.8% were cN-positive; the majority (86.8%) had grade 3 tumors and a Ki-67>20% (89.6%). Seventy-seven patients (72.6%) had TNBC. After a median follow-up of 49.8 months (range 0.1-69.1), 18 (15 in PO; 3 in PCb) iDFS events and 7 (6 in PO; 1 in PCb) deaths were reported. The 4-year survival rates are shown in the table below. iDFS (HR PO to PCb=2.86 [95%CI 0.83-9.9], log-rank p=0.081), DDFS (HR =3.03 [95%CI 0.67-13.67], log-rank p=0.129), and OS (HR=3.27 [95%CI 0.39-27.2], log-rank p=0.244) tended to be inferior with olaparib. Patients without g/tBRCA mutation seem to benefit from the use of carboplatinum (7/30 iDFS/DDFS events in PO; 0/16 in PCb, log-rank p=0.037, HR n.a.). Conclusions: In patients with HER2-negative and HRD breast cancer the use of olaparib instead of carboplatinum although showing comparable pCR rates, tended to result in an overall inferior outcome. This was mainly driven by the patients without a g/tBRCA mutation. In patients with a g/t BRCA mutation no difference between olaparib and carboplatinum was seen. Key words: Olaparib, HER2-negative breast cancer, HRD, survival Funding: The study was financially supported by AstraZeneca Citation Format: Peter A. Fasching, Sabine Schmatloch, Jan Hauke, Julia Rey, Christian Jackisch, Peter Klare, Theresa Link, Claus Hanusch, Jens Huober, Andrea Stefek, Sabine Seiler, Wolfgang D. Schmitt, Christoph Uleer, Gabriele Doering, Kerstin Rhiem, Andreas Schneeweiss, Carsten Denkert, Rita K. Schmutzler, Eric Hahnen, Michael Untch, Valentina Nekljudova, Jens-Uwe Blohmer, Sibylle Loibl. Neoadjuvant paclitaxel/olaparib in comparison to paclitaxel/carboplatinum in patients with HER2-negative breast cancer and homologous recombination deficiency – long-term survival of the GeparOLA study [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-06-13.

Abstract P2-01-02: Clinicopathological characteristics, treatment patterns and disease outcomes of germline BRCA1/2 carriers with early stage HER2-negative breast cancer and potential eligibility for adjuvant Olaparib

Abstract Background: Approximately 5-10% of early breast cancers (eBC) occur in patients (pts) carrying a germline BRCA1/2 (gBRCA1/2) pathogenic (P) or likely P (LP) variant. In the OlympiA trial, 1-year (yr) adjuvant (adj) olaparib (OLA) improved both invasive disease-free survival (iDFS) and overall survival (OS) in gBRCA carriers with high-risk HER2- eBC. Whether benefit of adj OLA might extend beyond the high-risk population defined by the OlympiA criteria remains to be defined. Methods: Consecutive pts who underwent surgery for a first diagnosis of eBC at Dana-Farber Brigham Cancer Center between 1/2016 and 8/2021 were identified. Genetic data were retrieved from an institutional dataset to identify gBRCA1/2 P/LP carriers tested through Dana-Farber. Clinicopathological variables, treatment and outcomes were characterized. Eligibility for adj OLA was based on the OlympiA study criteria, as follows: triple-negative BC (TNBC) with ≥pT2 or ≥pN1 prior to adj chemotherapy (ACT) or non-pCR after neo-adj CT (NACT); hormone receptor (HR)+ eBC with ≥4 positive nodes prior to ACT or non-pCR and CPS+EG score ≥3 after NACT. Results: We identified 188 gBRCA (105 BRCA1, 83 BRCA2) carriers with newly diagnosed HER2- eBC. Median age was 42.5 years and 119 (63%) were premenopausal. Tumor stage, grade and subtype are reported in Table 1. Recurrence Score (RS) was performed on 46 pts, with a median value of 25 (2% 0-10 RS, 52% 11-25 RS, 46% ≥26 RS). 97 pts (52%) received NACT, 55 (29%) ACT only and 36 (19%) did not receive CT. Most pts received both anthracyclines and taxanes, either as NACT (68%) or ACT (53%). 19 (20%) and 8 (8%) received platinum as NACT or ACT, respectively. 4 pts received adj OLA. 43 (44%) pts had a pCR after NACT. The pCR rate was higher in BRCA1 than BRCA2 carriers (52 vs 25%, odds ratio (OR) 3.27, p=0.015) and in pts with TNBC than HR+ eBC (50 vs 32%, OR 2.10, p=0.101). After a median follow up for survival of 37 months, 16 iDFS events were recorded, including 4 second primary tumors (3 ovarian and 1 pancreatic cancer). 3-yr iDFS was 89% (95% CI, 84-95) in the overall cohort, with no significant difference according to BRCA status (BRCA2 vs BRCA1: 85% vs 93%, hazard ratio [HR] 2.65 (95% CI, 0.92-7.63), p=0.071) or tumor subtype (HR+ vs TNBC: 87 vs 93%, HR 1.72 (95% CI, 0.60-4.94), p=0.316). 3-yr relapse-free survival (RFS) was 92% (95% CI, 87-97). 54 (29%) pts were potentially eligible for adj OLA. Eligible pts more frequently had TNBC (67 vs 36%, p< 0.001), higher stage (stage I 9 vs 55%, stage II 63 vs 37%, stage III 28 vs 9%), and grade 3 disease (85 vs 69%, p=0.045), were less likely to have ODX performed (2 vs 34%, p< 0.001), and more likely to have received NACT (83 vs 39%, p< 0.001) and radiation therapy (78 vs 33%, p< 0.001). 3-yr iDFS was 87% and 90% for pts eligible vs not eligible (HR 1.36 (95% CI, 0.49-3.74), p=0.555). 10/16 iDFS events occurred among not eligible pts. 3-yr RFS was lower in eligible pts (87 vs 94%; HR 2.23 (95% CI, 0.72-6.92), p=0.165). Conclusions: In our cohort, approximately 30% of pts were eligible for adj OLA. 3-yr iDFS was similar between pts eligible and not eligible for adj OLA according to OlympiA criteria. Our findings raise a concern regarding proper selection of all gBRCA carriers who may benefit from adj OLA. Further research is needed to identify additional groups of pts who may benefit from adding OLA to CT in higher risk disease or potentially replacing CT in lower risk settings. Table 1: Characteristics and outcomes of gBRCA1 vs gBRCA2 Citation Format: Stefania Morganti, Qingchun Jin, Julie Vincuilla, Ryan Buehler, Sean Ryan, Samantha Stokes, Tonia Parker, Elizabeth A. Mittendorf, Tari King, Anna Weiss, Ann Partridge, Brittany Bychkovsky, Giuseppe Curigliano, Nabihah Tayob, Nancy U. Lin, Judy Garber, Sara Tolaney, Filipa Lynce. Clinicopathological characteristics, treatment patterns and disease outcomes of germline BRCA1/2 carriers with early stage HER2-negative breast cancer and potential eligibility for adjuvant Olaparib [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-01-02.

Abstract GS1-05: Trial Assigning Individualized Options for Treatment (TAILORx): An Update Including 12-Year Event Rates

Abstract Background: Late recurrence of breast cancer after 5 years accounts for about 50% of recurrences in hormone receptor (HR)-positive early breast cancer (EBC). TAILORx established non-inferiority of adjuvant endocrine therapy (ET) given for at least 5 years to chemotherapy plus ET (CET) in EBC and a 21-gene recurrence score (RS) of 11-25, although there was some chemotherapy benefit in women Methods: Eligibility criteria included women 18-75 years with HR-positive, HER2-negative, T1b-T2N0 EBC who agreed to have CT assigned or randomized based on the RS assay. The primary endpoint was invasive disease-free survival (iDFS) in the RS 11-25 group. The “primary analysis” refers to the original prespecified analysis for the primary IDFS endpoint (836 IDFS events at full information in the RS 11-25 group) after a median of 7.5 years. The “updated analysis” was performed after a median followup of 11.0 and 10.4 years in the randomized and overall populations, respectively. Results:10,253 eligible women enrolled between 4/7/06-10/6/10.The updated analysis includes substantially more events that the primary analysis, including IDFS events (1819 vs. 1210), distant recurrences (561 vs. 384), locoregional +/- distant recurrences (764 vs. 543), and deaths (910 vs. 499). The table provides 5 and 12-year event rates (and standard errors) for all arms, and comparisons of the randomized arms. The primary trial conclusions remain unchanged: ET was non-inferior to CET in the randomized group with a RS 11-25. Although recurrence occurred in < 10% by 12 years for a RS 0-25, late recurrence events beyond 5 years exceeded earlier recurrence. Non-recurrence events occurred in about 13% at 12 years (~1%/year), contributing substantially to the IDFS rates. For women Conclusions: The current updated analysis confirms findings from the original primary analysis that ET is non-inferior to CET in HR-positive, HER2-negative, node-negative EBC and a RS 11-25. As in the original primary analysis, the subgroup of women Citation Format: Joseph Sparano, Robert J. Gray, Della Makower, Kathy S. Albain, Daniel F. Hayes, Charles Geyer, Elizabeth Dees, Matthew P. Goetz, John A. Olson Jr, Tracy G. Lively, Sunil Badve, Thomas Saphner, Lynne I. Wagner, Timothy Whelan, Virginia Kaklamani, George Sledge. Trial Assigning Individualized Options for Treatment (TAILORx): An Update Including 12-Year Event Rates [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS1-05.

Adjuvant palbociclib for ER+ breast cancer (PALLAS Trial (ABCSG-42/AFT-05/PrE0109/BIG-14-13): A preplanned analysis of the stage IIA cohort

390216 Background: CDK4/6 inhibitors have become standard of care for advanced hormone receptor positive, HER2-negative (HR+/HER2-) breast cancer in combination with endocrine therapy (ET), with one approved for high-risk patients (pts) in the adjuvant setting. The PALLAS Trial investigated the addition of palbociclib to adjuvant ET in pts with stage II-III breast cancer. Stage IIA patients were specifically enrolled to evaluate the potential benefit of using palbociclib with adjuvant ET pts diagnosed at lower risk who may have more indolent disease. Methods: In the prospective, randomized, phase III PALLAS trial, pts with HR+/HER2- early breast cancer were randomly assigned to receive adjuvant ET for at least 5 years with or without 2 years of palbociclib (125 mg orally once daily, days 1-21 of a 28-day cycle). ET was of provider’s choice. Stage IIA enrollment was capped at 1,000 patients. While the primary end point of the overall study was invasive disease-free survival (iDFS) for the entire cohort, there was a preplanned analysis of recurrence and survival endpoints in the stage IIA cohort. Outcomes were compared between arms using stratified log-rank tests and Cox models (stratification factors: chemotherapy and age ≤ 50). Results: Among 5,796 pts enrolled at 406 centers in 21 countries worldwide between 9/1/2015 and 11/30/2018, a total of 1,010 stage IIA pts were enrolled. The protocol-defined number of events occurred at a median follow-up of 50 months for this subgroup (43.1 months for the overall study). Median age within this subgroup was 54 (range 29-85 yrs), and 410 (40.6%) were pre/perimenopausal, 506 (50.1%) T2/N0 (vs T0-1/N1), 272 (26.9%) grade 3 (vs. grade1/2), and 561 (55.5%) received chemotherapy. iDFS events occurred in 31 of 503 (6.2%) pts who received palbociclib plus ET and in 45 of 507 (8.9%) pts who received ET alone, resulting in a statistically nonsignificant difference in iDFS at 4 years (92.9% vs. 92.1%; hazard ratio, 0.75; CI, 0.48 to 1.19; P = .23). Nonsignificant differences were also observed for invasive breast cancer-free, distant recurrence-free, and locoregional cancer-free survival. No significant differences in iDFS were observed in subgroups including age group, receipt of chemotherapy, tumor grade, and clinical risk (T1/N1 vs. T2/N0).Conclusions: In this preplanned analysis of the stage IIA cohort of the PALLAS trial, the addition of adjuvant palbociclib to standard ET did not improve outcomes over ET alone, suggesting no benefit from the agent in reducing the incidence of early relapse in pts with lower-stage HR+/HER2- breast cancer. Future analyses will incorporate genomic risk and other molecular patterns from the extensive transPALLAS correlative program. Additional follow-up (10-year minimum) is also underway to assess the impact of palbociclib exposure on late recurrence in HR+ disease. Clinical trial information: NCT02513394.

Adjuvant trastuzumab emtansine in HER2-positive breast cancer patients with HER2-negative residual invasive disease in KATHERINE

Following chemotherapy and human epidermal growth factor 2 (HER2)-targeted neoadjuvant therapy for HER2-positive early breast cancer, residual invasive breast cancer at surgery may be HER2-negative on retesting in some patients. We evaluated outcomes with T-DM1 and trastuzumab in patients randomized in the phase III KATHERINE trial based on HER2-positive central testing of the pre-treatment core biopsy with HER2-negative central testing on their corresponding surgical specimen after neoadjuvant treatment. In the 70/845 (8.3%) patients with HER2-negative residual disease on retesting at surgery, there were 11 IDFS events in the 42 trastuzumab-treated patients (26.2%) and none in the 28 T-DM1-treated patients, suggesting that T-DM1 should not be withheld in this patient population.

Abstract 507: Trop-2 expression in triple-negative breast cancer according to histological subtype: correlations with tumor infiltrating lymphocytes (TILs) and survival

Abstract Background: Trop-2 is a transmembrane calcium signal transducer highly expressed in multiple solid tumors including breast cancer. Limited data exist about associations between Trop-2 protein expression, clinicopathological characteristics and outcome in triple-negative breast cancers (TNBC). Given the approval of sacituzumab govitecan in unselected TNBC, its evaluation in other breast cancer settings and the emergence of other Trop-2 targeted antibody-drug conjugates, Trop-2 emerges as an important drug target in solid tumors. Methods: Trop-2-expression of patients with TNBC diagnosed between 2000-2017 at UZ Leuven was determined with IHC (ab227689, Abcam) (continuous and categorical variables, high 201-300, medium 100-200 and low <100 H-score). Associations of Trop-2-expression with age, BMI, germline BRCA status, tumor grade and size, histological subtype, lymphovascular invasion (LVI), presence of DCIS, nodal status, stromal TILs, androgen receptor (AR), standardized mitotic index, and outcome (invasive disease-free survival (iDFS), distant recurrence-free survival (D-RFi) and breast cancer-specific survival (BCSS)) were assessed. Associations with continuous variables were assessed by the Spearman correlation coefficient (ρ). Group differences were assessed by the Kruskal Wallis test for multiple groups or Mann-Whitney U test for two groups. Cox proportional hazards models were used to assess the association between Trop-2 expression and outcome. Results: Total of 658 patients with a median age at diagnosis of 53y (range 22-89y) were included, with median follow-up 9.6y. Low, medium and high Trop-2 expression was seen in 58.2%, 25.3% and 16.5% of cases. AR was positive in 25.5% of cases (10%-cutoff). Highest Trop-2 expression was observed in tumors with apocrine histology (median 180 score), and lowest expression in tumors with metaplastic histology (median 45 score) (p<.001). Higher Trop-2 expression was correlated with higher AR expression (10%-cutoff) (p=0.009), more presence of nodal involvement (p=0.016), associated DCIS (p=0.004) and LVI (p=0.006). Trop-2 expression was not associated with pathological complete response (pCR) observed in 22 of 64 patients treated with neoadjuvant chemotherapy (p=0.96). There was an iDFS events frequency of 199 out of 658 (30.2%). There was no correlation between Trop-2 expression and sTILs or outcome. Conclusion: In patients with TNBC in a large tertiary center, higher Trop-2 expression was correlated with apocrine histology, higher AR expression, more associated DCIS, more LVI and nodal involvement. There was no correlation between Trop-2 expression and sTILs or outcome. Citation Format: Hava Izci, Kevin Punie, Lise Waumans, Annouschka Laenen, Hans Wildiers, Freija Verdoodt, Christine Desmedt, Jan Ardui, Ann Smeets, Sileny Han, Ines Nevelsteen, Patrick Neven, Giuseppe Floris. Trop-2 expression in triple-negative breast cancer according to histological subtype: correlations with tumor infiltrating lymphocytes (TILs) and survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 507.