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Background: Ribociclib + endocrine therapy (ET) showed significant progression-free survival (PFS) and overall survival (OS) benefits in the MONALEESA trials in patients with HR+ /HER2 - advanced breast cancer (ABC). We report efficacy, safety, and patient-reported outcomes (PROs) across age groups, including older patients, in these trials., Methods: Data from the MONALEESA-2, -3, and -7 trials for pre- and postmenopausal patients receiving first-line treatment for ABC were pooled and analyzed by age (<65y, 65-74y, and ≥75y). PFS, OS, time to first chemotherapy (TTC), and time to definitive deterioration (TTD) in PROs were evaluated using Kaplan-Meier methods; a Cox regression model stratified by study and liver/lung metastasis was used for hazard ratios., Results: Among 1229 patients included, 63 % were < 65y, 27 % were 65-74y, and 10 % were ≥ 75y. Baseline characteristics were generally well balanced. Regardless of patient age, ribociclib+ET showed a consistent PFS and OS benefit and delayed TTC. With ribociclib+ET, the most common first subsequent treatment was ET. Safety results were consistent with those in the overall trial population; no new signals were identified. Rates of discontinuation due to AEs with ribociclib+ET were numerically higher in patients ≥ 75y. Among patients who discontinued treatment due to AEs, the percentage without prior dose reduction was higher in those ≥ 75y. A PRO benefit with ribociclib+ET was observed across all age groups for pain and fatigue scores., Conclusions: This analysis demonstrated that ribociclib+ET is an effective and well-tolerated treatment for patients of all age groups with HR+ /HER2 - ABC, including older patients. (MONALEESA-2, NCT01958021; MONALEESA-3, NCT02422615; MONALEESA-7, NCT02278120)., Competing Interests: Declaration of Competing Interest L. Hart reports institutional grants and personal fees from Novartis. S-A. Im reports personal fees from AstraZeneca, Novartis, Hanmi, Pfizer, Eisai, Roche, Lilly, GSK, MSD, Daiichi Sankyo, Idience, Bertis; research grants from AstraZeneca, Pfizer, Eisai, Roche, Daewoong Pharm, Boryung Pharm, Daiichi Sankyo. S. M. Tolaney reports institutional grants from Eli Lilly, Novartis, AstraZeneca, Merck, Nektar, Pfizer, Genentech/Roche, Exelixis, Bristol Myers Squibb, Eisai, NanoString, Cyclacel, Sanofi, Odonate, Gilead; personal fees from Eli Lilly, Novartis, AstraZeneca, Merck, Nektar, Pfizer, Genentech/Roche, Exelixis, Bristol Myers Squibb, Eisai, NanoString, Puma, Sanofi, Odonate, Seagen, G1 Therapeutics, Athenex, OncoPep, Kyowa Kirin Pharmaceuticals, Daiichi Sankyo, CytomX, Samsung Bioepis Inc., Certara, Mersana Therapeutics, Gilead, OncoSec, Chugai Pharma, Ellipses Pharma, 4D Pharma, BeyondSpring Pharma, OncXerna, Infinity Therapeutics, Zentalis, Zymeworks. M. Campone reports institutional grants from Pfizer, AstraZeneca, Sanofi, Gilead, Novartis, Lilly, AbbVie, Servier, Sandoz, Accord. T. J. Pluard has nothing to disclose. B. Sousa has nothing to disclose. G. Freyer has nothing to disclose. T. Decker reports personal fees from Novartis, iOMEDICO. K. Kalinsky reports personal fees from Eli Lilly, Pfizer, Novartis, AstraZeneca, Daiichi Sankyo, Puma, 4D Pharma, OncoSec, Immunomedics, Merck, Seagen, Mersana, Cyclacel, Myovant; institutional research funding grants from Genentech/Roche, Novartis, Eli Lilly, AstraZeneca, Daiichi Sankyo, Ascentage; spouse was prior employee of EQRX, GRAIL for which employment and stock ownership is reported. G. Sopher, M. Gao, H. Hu report employment and stock ownership from Novartis. S. Kuemmel reports personal fees from Roche, Celgene, Novartis, AstraZeneca, Pfizer, Lilly, Amgen, Somatex, Daiichi Sankyo, PFM Medical, MSD Oncology, SonoScape, Gilead Sciences, Agendia; travel and accommodation support from Roche, Daiichi Sankyo; uncompensated relationship with WSG., (Copyright © 2025 Elsevier Ltd. All rights reserved.)

Harmonized global collaborations are crucial to improving outcomes in hormone sensitive operable breast cancer.

Purpose: The global, phase 3, open-label, randomized TROPION-Breast01 study assessed the trophoblast cell surface antigen 2-directed antibody-drug conjugate datopotamab deruxtecan (Dato-DXd) versus investigator's choice of chemotherapy (ICC) in hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) breast cancer., Methods: Adult patients with inoperable/metastatic HR+/HER2‒ breast cancer, who had disease progression on endocrine therapy, for whom endocrine therapy was unsuitable, and had received one to two previous lines of chemotherapy in the inoperable/metastatic setting, were randomly assigned 1:1 to Dato-DXd (6 mg/kg once every 3 weeks) or ICC (eribulin/vinorelbine/capecitabine/gemcitabine). Dual primary end points were progression-free survival (PFS) by blinded independent central review (BICR) and overall survival (OS)., Results: Patients were randomly assigned to Dato-DXd (n = 365) or ICC (n = 367). Dato-DXd significantly reduced the risk of progression or death versus ICC (PFS by BICR hazard ratio [HR], 0.63 [95% CI, 0.52 to 0.76]; P < .0001). Consistent PFS benefit was observed across subgroups. Although OS data were not mature, a trend favoring Dato-DXd was observed (HR, 0.84 [95% CI, 0.62 to 1.14]). The rate of grade ≥3 treatment-related adverse events (TRAEs) with Dato-DXd was lower than ICC (20.8% v 44.7%). The most common TRAEs (any grade; grade ≥3) were nausea (51.1%; 1.4%) and stomatitis (50%; 6.4%) with Dato-DXd and neutropenia (grouped term, 42.5%; 30.8%) with ICC., Conclusion: Patients receiving Dato-DXd had statistically significant and clinically meaningful improvement in PFS and a favorable and manageable safety profile, compared with ICC. Results support Dato-DXd as a novel treatment option for patients with inoperable/metastatic HR+/HER2‒ breast cancer who have received one to two previous lines of chemotherapy in this setting.

Purpose: Cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) combined with endocrine therapy (ET) are the standard first-line treatment for hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC); however, disease progression occurs in almost all patients and additional treatment options are needed. Herein, we report outcomes of the postMONARCH trial investigating a switch in ET with/without CDK4/6 inhibition with abemaciclib after disease progression on CDK4/6i., Methods: This double-blind, randomized phase III study enrolled patients with disease progression on previous CDK4/6i plus aromatase inhibitor as initial therapy for advanced disease or recurrence on/after adjuvant CDK4/6i + ET. Patients were randomly assigned (1:1) to abemaciclib + fulvestrant or placebo + fulvestrant. The primary end point was investigator-assessed progression-free survival (PFS). Secondary end points included PFS by blinded independent central review, objective response rate (ORR), and safety., Results: This study randomly assigned 368 patients (abemaciclib + fulvestrant, n = 182 placebo + fulvestrant, n = 186). At the primary analysis (258 events), the hazard ratio (HR) was 0.73 (95% CI, 0.57 to 0.95; nominal P = .017), with median PFS 6.0 (95% CI, 5.6 to 8.6) versus 5.3 (95% CI, 3.7 to 5.6) months and 6-month PFS rates of 50% and 37% in the abemaciclib + fulvestrant and placebo + fulvestrant arms, respectively. These results were supported by BICR-assessed PFS (HR, 0.55 [95% CI, 0.39 to 0.77]; nominal P < .001). A consistent treatment effect was seen across major clinical and genomic subgroups, including with/without ESR1 or PIK3CA mutations. Among patients with measurable disease, investigator-assessed ORR was improved with abemaciclib + fulvestrant versus placebo + fulvestrant (17% v 7%; nominal P = .015). No new safety signals were observed, with findings consistent with the known safety profile of abemaciclib., Conclusion: Abemaciclib + fulvestrant significantly improved PFS after disease progression on previous CDK4/6i + ET in patients with HR+, HER2- ABC, offering an additional targeted therapy option for these patients.

Background: The phase III RxPONDER trial has impacted treatment for node-positive(1-3), hormone receptor-positive, HER2-negative breast cancer with 21-gene recurrence score (RS) ≤ 25. We investigated how these findings apply to different racial and ethnic groups within the trial., Methods: The trial randomized women to endocrine therapy (ET) or to chemotherapy plus ET. The primary clinical outcome was invasive disease-free survival (IDFS) with distant relapse-free survival (DRFS) as a secondary outcome. Multivariable Cox models were used to evaluate the association between race/ethnicity and survival outcomes, adjusting for clinicopathologic characteristics, RS, and treatment., Results: A total of 4,048 women with self-reported race/ethnicity were included: Hispanic (15.1%), non-Hispanic Black (NHB)(6.1%), Native American/Pacific Islander (0.8%), Asian (8.0%), and non-Hispanic White (NHW)(70%). No differences in RS distribution, tumor size, or number of positive nodes were observed by race/ethnicity. Relative to NHWs, IDFS was worse for NHBs (5-year IDFS 91.6% vs 87.1%, HR = 1.37; 95% CI 1.03-1.81) and better for Asians (91.6% vs 93.9%, HR = 0.64; 95% CI 0.46-0.91). Relative to NHW, DRFS was worse for NHBs (5-year DRFS 95.8% vs 91.0%, HR = 1.65; 95% CI 1.17-2.32) and better for Asians (95.8% vs 96.7%, HR = 0.59; 95% CI 0.37-0.95). Adjusting for clinical characteristics, particularly body mass index, diminished the effect of race on outcomes. Chemotherapy treatment efficacy did not differ by race/ethnicity., Conclusions: NHB women had worse clinical outcomes compared to NHWs in the RxPONDER trial despite similar RS and comparable treatment. Our study emphasizes the persistent racial disparities in breast cancer outcomes while highlighting complex interactions among contributing factors., Trial Registration: ClinicalTrials.gov: NCT01272037., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Sequential adaptive trial designs can help accomplish the goals of personalized medicine, optimizing outcomes and avoiding unnecessary toxicity. Here we describe the results of incorporating a promising antibody-drug conjugate, datopotamab-deruxtecan (Dato-DXd) in combination with programmed cell death-ligand 1 inhibitor, durvalumab, as the first sequence of therapy in the I-SPY2.2 phase 2 neoadjuvant sequential multiple assignment randomization trial for high-risk stage 2/3 breast cancer. The trial includes three blocks of treatment, with initial randomization to different experimental agent(s) (block A), followed by a taxane-based regimen tailored to tumor subtype (block B), followed by doxorubicin-cyclophosphamide (block C). Subtype-specific algorithms based on magnetic resonance imaging volume change and core biopsy guide treatment redirection after each block, including the option of early surgical resection in patients predicted to have a high likelihood of pathologic complete response, which is the primary endpoint assessed when resection occurs. There are two primary efficacy analyses: after block A and across all blocks for six prespecified HER2-negative subtypes (defined by hormone receptor status and/or response-predictive subtypes). In total, 106 patients were treated with Dato-DXd/durvalumab in block A. In the immune-positive subtype, Dato-DXd/durvalumab exceeded the prespecified threshold for success (graduated) after block A; and across all blocks, pathologic complete response rates were equivalent to the rate expected for the standard of care (79%), but 54% achieved that result after Dato-DXd/durvalumab alone (block A) and 92% without doxorubicin-cyclophosphamide (after blocks A + B). The treatment strategy across all blocks graduated in the hormone-negative/immune-negative subtype. No new toxicities were observed. Stomatitis was the most common side effect in block A. No patients receiving block A treatment alone had adrenal insufficiency. Dato-DXd/durvalumab is a promising therapy combination that can eliminate standard chemotherapy in many patients, particularly the immune-positive subtype.ClinicalTrials.gov registration: NCT01042379 ., Competing Interests: Competing interests: R.A.S. reports institutional research funding from OBI Pharma, QLHC, AstraZeneca and Gilead; serves on AstraZeneca and Stemline Advisory Boards and Gilead Speaker’s Bureau; and has a consultancy role with QLHC. M.S.T. reports institutional research funding from Lilly, Gilead Sciences, Phoenix Molecular Designs, AstraZeneca, Regeneron, Merck and Novartis. C.Y. reports institutional research grant from NCI/NIH; salary support and travel reimbursement from QLHC; US patent titled, ‘Breast cancer response prediction subtypes’ (no. 18/174,491); and University of California Inventor Share. R.N. reports research funding from Arvinas, AstraZeneca, BMS, Corcept Therapeutics, Genentech/Roche, Gilead, GSK, Merck, Novartis, OBI Pharma, OncoSec, Pfizer, Relay, Seattle Genetics, Sun Pharma and Taiho Oncology and advisory roles with AstraZeneca, BeyondSpring, Daiichi Sankyo, Exact Sciences, Fujifilm, GE, Gilead, Guardant Health, Infinity, iTeos, Merck, Moderna, Novartis, OBI, OncoSec, Pfizer, Sanofi, Seagen and Stemline. H.S.R. reports institutional research support from AstraZeneca, Daiichi Sankyo, F. Hoffmann-La Roche AG/Genentech, Gilead Sciences, Lilly, Merck & Co., Novartis Pharmaceuticals Corporation, Pfizer, Stemline Therapeutics, OBI Pharma, Ambrx and Greenwich Pharma and has advisory and consulting roles with Chugai, Puma, Sanofi, Napo and Mylan. M.D. reports research grants from NIH/NCI and NIH/NIA, and contracts from PCORI. A.J.C. reports institutional research funding from Merck, Amgen, Puma, Seagen, Pfizer and Olema and has advisory roles with AstraZeneca and Genentech. E.S.-R. reports grants from V Foundation, NIH and Susan G. Komen; institutional research funding from GSK, Seagen, Pfizer and Lilly; and consulting and honoraria from Novartis, Merck, Seagen, AstraZeneca and Lilly; is a Cancer Awareness Network Board member and receives support from ASCO and NCCN. J.C.B. reports institutional research funding from Eli Lilly and SymBioSis, participation on the Data Safety Monitoring Committee of Cairn Surgical and honoraria from PER, PeerView, OncLive, EndoMag and UpToDate. C.O. reports consulting fees from AstraZeneca, Guardant Health and Jazz Pharmaceuticals. K.K. reports advisory and consultant roles for Eli Lilly, Pfizer, Novartis, AstraZeneca, Daiichi Sankyo, Puma, 4D Pharma, OncoSec, Immunomedics, Merck, Seagen, Mersana, Menarini Silicon Biosystems, Myovant, Takeda, Biotheranostics, Regor, Gilead, Prelude Therapeutics, RayzeBio, eFFECTOR Therapeutics and Cullinan Oncology and reports institutional research funding from Genentech/Roche, Novartis, Eli Lilly, AstraZeneca, Daiichi Sankyo and Ascentage. A.D.E. reports support from Scorpion, Infinity and Deciphera. C.V. reports institutional research funding from Pfizer, Seagen, H3 Biomedicine/Eisai, AstraZeneca and CytomX; research funding to their previous institution from Genentech, Roche, Pfizer, Incyte, Pharmacyclics, Novartis, TRACON Pharmaceuticals, Innocrin Pharmaceuticals, Zymeworks and H3 Biomedicine; advisory and consulting roles with Guidepoint, Novartis, Seagen, Daiichi Sankyo, AstraZeneca and Cardinal Health; unpaid consulting with Genentech; and participation in non-CME activity with Gilead and AstraZeneca. N.W. reports participation on Gilead’s Advisory Board and honoraria from OncLive, NCCN and Total Health Conferencing. K.S.A. reports institutional research funding from AstraZeneca, Daiichi Sankyo, Seattle Genetics, QLHC and the IDSM committee at Seattle Genetics. A.S.C. reports institutional research funding from Novartis and Lilly. C.F. reports honoraria from Curio Science and OncLive and institutional research funding from Eli Lily. C.I. reports institutional research funding from Tesaro/GSK, Seattle Genetics, Pfizer, AstraZeneca, BMS, Genentech, Novartis and Regeneron; consultancy roles with AstraZeneca, Genentech, Gilead, ION, Merck, Medscape, MJH Holdings, Novartis, Pfizer, Puma and Seagen; and royalties from Wolters Kluwer (UpToDate) and McGraw Hill (Goodman and Gilman). A.T. owns stock at Johnson & Johnson, Gilead, Bristol Myers Squibb; reports participation on Pfizer’s Advisory Board: AstraZeneca; reports institutional research funding from Merck and Sanofi; and has royalties from UpToDate. J.T. serves as institutional principal investigator for clinical trial with Intuitive Surgical and is the Editor Lead for ABS, CGSO, SCORE, Breast Education Committee Track Leader, ASCO SESAP 19 and Breast Co-Chair, ACS. K.Y. received research support unrelated to this work and paid to the institution from Pfizer, Gilead, Seagen, Dantari Pharmaceuticals, Treadwell Therapeutics and Relay Therapeutics and support from American Cancer Society IRG grant (no. IRG-19-230-48-IRG), UC San Diego Moores Cancer Center, Specialized Cancer Center support grant NIH/NCI (P30CA023100) and Curebound Discovery Award (2023, 2024). L.H. reports advisory and consultancy roles with Pfizer, and AstraZeneca. K.G. reports participation in advisory boards with honoraria to the institution from AstraZeneca, Novartis, Puma Biotechnologies, Eli Lilly, Gilead, Exact Sciences, NeoGenomics and TerSera Therapeutics. F.M.H. reports consultancy for Novartis. T.S. reports honoraria from Hologic. A.L.A., P.B. and P.N. are employees of QLHC. G.L.H. reports an institutional research grant from NIH (1R01CA255442). W.F.S. reports shares in IONIS Pharmaceuticals and Eiger Biopharmaceuticals; received consulting fees from AstraZeneca; is a cofounder with equity in Delphi Diagnostics; and issued patents for: (1) a method to calculate residual cancer burden, and (2) genomic signature to measure sensitivity to endocrine therapy. J.P. reports honoraria from Methods in Clinical Research (Faculty SCION Workshop) and support from ASCO and Advocate Scholarship; AACR (SSP Program); and VIVLI, U Wisc SPORE (EAB), QuantumLEAD (COVID DSMB), PCORI; is a reviewer; and is an I-SPY advocate lead. P.P. reports institutional research funding from Genentech/Roche, Fabre-Kramer, Advanced Cancer Therapeutics, Caris Centers of Excellence, Pfizer, Pieris Pharmaceuticals, Cascadian Therapeutics, Bolt, Byondis, Seagen, Orum Therapeutics and Carisma Therapeutics; consulting fees from Personalized Cancer Therapy, OncoPlex Diagnostics, Immunonet BioSciences, Pfizer, HERON, Puma Biotechnology, Sirtex, Caris Life Sciences, Juniper, Bolt Biotherapeutics and AbbVie; honoraria from Dava Oncology, OncLive/MJH Life Sciences, Frontiers (Publisher), SABCS and ASCO; Speakers’ Bureau: Genentech/Roche (past); and US patent no. 8,486,413, US patent no. 8,501,417, US patent no. 9,023,362 and US patent no. 9,745,377; and uncompensated roles with Pfizer, Seagen and Jazz. A.D.M. reports institutional research funding from Novartis, Pfizer, Genentech and NeoGenomics and is a program chair of the Scientific Advisory Committee, ASCO. D.Y. reports research funding from NIH/NCI: P30CA 077598, P01CA234228-01 and R01CA251600; consulting fees from Martell Diagnostics; and honoraria and travel for speaking at the ‘International Breast Cancer Conference’. L.J.v.V. is a founding advisor and shareholder of Exai Bio and is a part-time employee and owns stock in Agendia. N.M.H. reports institutional research funding from NIH. L.J.E. reports funding from Merck & Co., participation on an advisory board for Blue Cross Blue Shield, and personal fees from UpToDate and is an unpaid board member of QLHC. All other authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Nature America, Inc.)

Purpose: To investigate the safety, tolerability, pharmacokinetics (PK), and preliminary antitumor activity of inavolisib, a potent and selective small-molecule inhibitor of p110α that promotes the degradation of mutated p110α, in combination with palbociclib and endocrine therapy (ET), in a phase I/Ib study in patients with PIK3CA -mutated, hormone receptor-positive/human epidermal growth factor receptor 2-negative locally advanced/metastatic breast cancer (ClinicalTrials.gov identifier: NCT03006172)., Methods: Women ≥18 years of age received inavolisib, palbociclib, and letrozole (Inavo + Palbo + Letro arm) or fulvestrant (Inavo + Palbo + Fulv arm) until unacceptable toxicity or disease progression. The primary objective was to evaluate safety or tolerability., Results: Fifty-three patients were included, 33 in the Inavo + Palbo + Letro arm and 20 in the Inavo + Palbo + Fulv arm. Median duration of inavolisib treatment was 15.7 and 20.8 months (cutoff: March 27, 2023), respectively. Treatment-related adverse events (TRAEs) occurred in all patients; the most frequent were stomatitis, hyperglycemia, and diarrhea; grade ≥3 any TRAE rates were 87.9% and 85.0%; 6.1% and 10.0% discontinued any treatment due to TRAEs in the Inavo + Palbo + Letro and Inavo + Palbo + Fulv arms, respectively. No PK drug-drug interactions (DDIs) were observed among the study treatments when administered. Confirmed objective response rates were 52.0% and 40.0% in patients with measurable disease, and median progression-free survival was 23.3 and 35.0 months in the Inavo + Palbo + Letro and Inavo + Palbo + Fulv arms, respectively. Available paired pre- and on-treatment tumor tissue and circulating tumor DNA analyses confirmed the effects of study treatment on pharmacodynamic and pathophysiologic biomarkers of response., Conclusion: Inavolisib plus palbociclib and ET demonstrated a manageable safety profile, lack of DDIs, and promising preliminary antitumor activity.

Purpose: To explore the feasibility of imaging amino-acid transport and PSMA molecular pathways in the detection of metastatic breast invasive lobular carcinoma (ILC) and if there is superior detection compared to standard-of-care imaging [computed tomography (CT)/bone scan, or 18 F-FDG positron-emission-tomography (PET)-CT]., Methods: 20 women with de-novo or suspected metastatic ILC underwent two PET-CT scans with 18 F-fluciclovine and 68 Ga-PSMA-11 on separate days. Uptake per patient and in 3 regions per patient - ipsilateral axillary lymph node (LN), extra-axillary LN (ipsilateral supraclavicular or internal mammary), or distant sites of disease - was compared to standard-of-care imaging (CT/bone scan in 13 patients and 18 F-FDG PET-CT in 7 patients). Results were correlated to a composite standard of truth. Confirmed detection rate (cDR) was compared using McNemar's test. Mean SUVmax of 18 F-fluciclovine and 68 Ga-PSMA-11 in the most avid lesion for each true positive metastatic region and intact primary lesion were compared by t-test., Results: The cDR for standard-of-care imaging was 5/20 patients in 5/60 regions. 68 Ga-PSMA-11 PET-CT detected metastasis in 7/20 patients in 7/60 regions. 18 F-fluciclovine PET-CT detected metastasis in 9/20 patients in 12/60 regions. The cDR for 18 F-fluciclovine PET-CT was significantly higher versus standard-of-care imaging on the patient and combined region levels, while there were no significant differences between 68 Ga-PSMA-11 and standard-of care imaging. 18 F-fluciclovine cDR was also significantly higher than 68 Ga-PSMA-11 on the combined region level. Mean SUVmax for true positive metastatic and primary lesions with 18 F-fluciclovine (n = 18) was significantly greater than for 68 Ga-PSMA-11 (n = 11) [5.5 ± 1.8 versus 3.5 ± 2.7 respectively, p = 0.021]., Conclusion: In this exploratory trial, 18 F-fluciclovine PET-CT has a significantly higher cDR for ILC metastases compared to standard-of-care imaging and to 68 Ga-PSMA-11. Mean SUVmax for true positive malignancy was significantly higher with 18 F-fluciclovine than for 68 Ga-PSMA-11. Exploratory data from this trial suggests that molecular imaging of amino acid metabolism in patients with ILC deserves further study., Clinical Trial Registration: Early phase (I-II) clinical trial (NCT04750473) funded by the National Institutes of Health (R21CA256280)., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Patients with metastatic triple-negative breast cancer (mTNBC) have poor prognosis and limited treatment options. Sacituzumab govitecan (SG), a Trop-2-directed antibody-drug conjugate, is approved for patients with mTNBC who have received ≥ 2 systemic therapies (≥ 1 in the metastatic setting) based on the ASCENT study (NCT02574455). The current study describes real-world SG use and outcomes in patients with mTNBC in the United States., Methods: This retrospective, observational study included adult patients with mTNBC from the ConcertAI Patient360™ database who received SG in the second line (2L) and later from April 2020 to May 2022. SG use patterns, effectiveness, and tolerability are described., Results: This analysis included 230 patients (median age 60 years, 26% Black, 17% with ECOG performance status ≥ 2, 66% in community settings; median of 2 prior lines of treatment in the metastatic setting); median follow-up was 7.2 months. Median (95% CI) real-world overall survival was 10.0 (8.3-11.1) months for all patients and 13.9 (9.8-not estimable) months in the 2L subgroup (n = 77). Granulocyte-colony stimulating factor (G-CSF) was administered concomitantly with SG in 134 (58%) patients; 35 (15%) received G-CSF for the first time. Median (IQR) time from SG start to G-CSF use was 8.5 (8.0-29.0) days. Seventeen (7%) patients discontinued SG due to toxicity., Conclusions: Using a real-world, ethnically diverse population of patients with mTNBC presenting with poor prognosis, these data reinforced the findings from ASCENT. In routine clinical practice, SG is an effective treatment in the 2L setting, consistent with treatment guidelines., (© 2024. The Author(s).)

Background: Inavolisib is a highly potent and selective inhibitor of the alpha isoform of the p110 catalytic subunit of the phosphatidylinositol 3-kinase complex (encoded by PIK3CA ) that also promotes the degradation of mutated p110α. Inavolisib plus palbociclib-fulvestrant has shown synergistic activity in preclinical models and promising antitumor activity in early-phase trials., Methods: In a phase 3, double-blind, randomized trial, we compared first-line inavolisib (at an oral dose of 9 mg once daily) plus palbociclib-fulvestrant (inavolisib group) with placebo plus palbociclib-fulvestrant (placebo group) in patients with PIK3CA -mutated, hormone receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative locally advanced or metastatic breast cancer who had had relapse during or within 12 months after the completion of adjuvant endocrine therapy. The primary end point was progression-free survival as assessed by the investigator., Results: A total of 161 patients were assigned to the inavolisib group and 164 to the placebo group; the median follow-up was 21.3 months and 21.5 months, respectively. The median progression-free survival was 15.0 months (95% confidence interval [CI], 11.3 to 20.5) in the inavolisib group and 7.3 months (95% CI, 5.6 to 9.3) in the placebo group (hazard ratio for disease progression or death, 0.43; 95% CI, 0.32 to 0.59; P<0.001). An objective response occurred in 58.4% of the patients in the inavolisib group and in 25.0% of those in the placebo group. The incidence of grade 3 or 4 neutropenia was 80.2% in the inavolisib group and 78.4% in the placebo group; grade 3 or 4 hyperglycemia, 5.6% and 0%, respectively; grade 3 or 4 stomatitis or mucosal inflammation, 5.6% and 0%; and grade 3 or 4 diarrhea, 3.7% and 0%. No grade 3 or 4 rash was observed. Discontinuation of any trial agent because of adverse events occurred in 6.8% of the patients in the inavolisib group and in 0.6% of those in the placebo group., Conclusions: In patients with PIK3CA -mutated, hormone receptor-positive, HER2-negative locally advanced or metastatic breast cancer, inavolisib plus palbociclib-fulvestrant led to significantly longer progression-free survival than placebo plus palbociclib-fulvestrant, with a greater incidence of toxic effects. The percentage of patients who discontinued any trial agent because of adverse events was low. (Funded by F. Hoffmann-La Roche; INAVO120 ClinicalTrials.gov number, NCT04191499.)., (Copyright © 2024 Massachusetts Medical Society.)

Anti-oestrogen-based therapies, often combined with a CDK4/6 inhibitor, are the current standard-of-care first-line therapy for patients with advanced-stage hormone receptor-positive (HR + ) breast cancer. Resistance to anti-oestrogen agents inevitably occurs, mediated by oestrogen receptor (ER)-dependent or ER-independent mechanisms that drive tumour progression. Emerging endocrine therapies include, but are not limited to, next-generation oral ER degraders and proteolysis targeting chimeras, which might be particularly effective in patients with ESR1-mutant breast cancer. Furthermore, cancers harbouring driver alterations in oncogenic signalling pathways, including AKT and PI3K, might be susceptible to novel combination strategies involving targeted inhibitors. Next-generation CDK2/4 inhibitors are an area of active clinical investigation, and efforts are ongoing to evaluate the role of sequential CDK inhibition. Approved and emerging antibody-drug conjugates exploiting novel target antigens have also demonstrated promising clinical activity. These novel agents, as well as further identification and characterization of predictive biomarkers, will hopefully continue to improve clinical outcomes, reduce the incidence of toxicities, and limit the extent of overtreatment in this population. In this Review, we describe the evolving treatment paradigm for patients with metastatic HR + breast cancer in light of the growing armamentarium of drugs and biomarkers that will help to shape the future therapeutic landscape. These strategies are expected to involve tumour molecular profiling to enable the delivery of precision medicine., (© 2024. Springer Nature Limited.)

Tuning immune-cold tumor hot has largely attracted attention to improve cancer treatment, including immunotherapy and antibody-drug conjugates (ADCs). Utilizing multiomic analyses and experimental validation, this work identifies a pivotal role for the USP10/B7-H4 proteolytic axis in mediating the interplay between tumor immune responses and ADC efficacy, particularly for sacituzumab govitecan (SG) in treating triple negative breast cancers (TNBCs). Mechanistically, the inhibition of autocrine motility factor receptor (AMFR)-mediated ubiquitylation of B7-H4 by the deubiquitinase USP10 leads to the stabilization of B7-H4, which suppresses tumor immune activity and reduces SG treatment effectiveness. Pharmacological inhibition of USP10 promotes the degradation of B7-H4, enhancing tumor immunogenicity and consequently improving the tumor-killing efficacy of SG. In preclinical TNBC models, suppression of USP10/B7-H4 proteolytic axis is effective in increasing SG killing efficacy and reducing tumor growth, especially for the tumors with the USP10 high /B7-H7 high signature. Collectively, these findings uncover a novel strategy for targeting the immunosuppressive molecule B7-H4 for cancer therapy., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

Background: The treatment landscape for HR(+)HER2(-) metastatic breast cancer (MBC) is evolving for patients with ESR1 mutations (mut) and PI3K/AKT pathway genomic alterations (GA). We sought to inform clinical utility for comprehensive genomic profiling (CGP) using tissue (TBx) and liquid biopsies (LBx) in HR(+)HER2(-) MBC., Methods: Records from a de-identified breast cancer clinicogenomic database for patients who underwent TBx/LBx testing at Foundation Medicine during routine clinical care at ~ 280 US cancer clinics between 01/2011 and 09/2023 were assessed. GA prevalence [ESR1mut, PIK3CAmut, AKT1mut, PTENmut, and PTEN homozygous copy loss (PTENloss)] were calculated in TBx and LBx [stratified by ctDNA tumor fraction (TF)] during the first three lines of therapy. Real-world progression-free survival (rwPFS) and overall survival (rwOS) were compared between groups by Cox models adjusted for prognostic factors., Results:  ~ 60% of cases harbored 1 + GA in 1st-line TBx (1266/2154) or LBx TF ≥ 1% (80/126) and 26.5% (43/162) in LBx TF < 1%. ESR1mut was found in 8.1% TBx, 17.5% LBx TF ≥ 1%, and 4.9% LBx TF < 1% in 1st line, increasing to 59% in 3rd line (LBx TF ≥ 1%). PTENloss was detected at higher rates in TBx (4.3%) than LBx (1% in TF ≥ 1%). Patients receiving 1st-line aromatase inhibitor + CDK4/6 inhibitor (n = 573) with ESR1mut had less favorable rwPFS and rwOS versus ESR1 wild-type; no differences were observed for fulvestrant + CDK4/6 inhibitor (n = 348)., Conclusion: Our study suggests obtaining TBx for CGP at time of de novo/recurrent diagnosis, followed by LBx for detecting acquired GA in 2nd + lines. Reflex TBx should be considered when ctDNA TF < 1%., (© 2024. The Author(s).)

Acquired resistance to PARP inhibitors (PARPi) remains a treatment challenge for BRCA1/2-mutant breast cancer that drastically shortens patient survival. Although several resistance mechanisms have been identified, none have been successfully targeted in the clinic. Using new PARPi-resistance models of Brca1- and Bard1-mutant breast cancer generated in-vivo, we identified FLT1 (VEGFR1) as a driver of resistance. Unlike the known role of VEGF signaling in angiogenesis, we demonstrate a novel, non-canonical role for FLT1 signaling that protects cancer cells from PARPi in-vivo through a combination of cell-intrinsic and cell-extrinsic pathways. We demonstrate that FLT1 blockade suppresses AKT activation, increases tumor infiltration of CD8 + T cells, and causes dramatic regression of PARPi-resistant breast tumors in a T-cell-dependent manner. Moreover, PARPi-resistant tumor cells can be readily re-sensitized to PARPi by targeting Flt1 either genetically (Flt1-suppression) or pharmacologically (axitinib). Importantly, a retrospective series of breast cancer patients treated with PARPi demonstrated shorter progression-free survival in cases with FLT1 activation at pre-treatment. Our study therefore identifies FLT1 as a potential therapeutic target in PARPi-resistant, BRCA1/2-mutant breast cancer., (© 2024. The Author(s).)

Purpose: Although patients with metastatic breast cancer (MBC) have been living longer with the advent of more effective treatments such as targeted therapy and immunotherapy, the disease remains incurable, and most patients will undergo therapy indefinitely. When beginning therapy, patients are typically prescribed dose often based upon the maximum tolerated dose identified in phase I clinical trials. However, patients' perspectives about tolerability and willingness to discuss individualized dosing of drugs upon initiation of a new regimen and throughout the course of treatment have not been comprehensively evaluated., Methods: Patient advocates and medical oncologists from the Patient-Centered Dosing Initiative (PCDI) developed a survey to ascertain the prevalence and severity of MBC patients' treatment-related side effects, the level of patient-physician communication, mitigation strategies, perception about the relative efficacy of higher versus lower doses, and willingness to discuss alternative dosing. The PCDI distributed the anonymous confidential online survey in August 2020 to individuals with self-reported MBC., Results: One thousand and two hundred twenty-one patients with MBC completed the survey. 86.1% (n = 1,051) reported experiencing at least one significant treatment-related side effect, and of these, 20.3% (n = 213) visited the emergency room/hospital and 43.2% (n = 454) missed at least one treatment. Nearly all patients with side effects (97.6%, n = 1,026) informed their doctor and 81.7% (n = 838) received assistance. Of the 556 patients given a dose reduction for side-effect mitigation, 82.6% (n = 459) reported relief. Notably, majority of patients (53.3%, n = 651) do not believe that higher dose is always more effective than lower dose, and 92.3% (n = 1,127) would be willing to discuss flexible dosing options with their physicians based upon personal characteristics to optimize quality of life., Conclusion: Given that the majority of patients with MBC experienced at least one substantial treatment-related side effect and most patients given a dose reduction reported improvement, innovative dosage-related strategies are warranted to sustain and improve patients' well-being. Patient-physician discussions in which the patient's unique attributes and circumstances are assessed upon initiation of new treatment and throughout the course of therapy may facilitate the identification of the most favorable dose for each patient, and the majority of patients would be receptive to this approach.

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported. Sacituzumab govitecan (SG), a first-in-class anti-trophoblast cell surface antigen 2 (Trop-2) antibody-drug conjugate, demonstrated superior efficacy over single-agent chemotherapy (treatment of physician's choice [TPC]) in patients with metastatic triple-negative breast cancer (mTNBC) in the international, multicenter, phase III ASCENT study.Patients were randomly assigned 1:1 to receive SG or TPC until unacceptable toxicity/progression. Final efficacy secondary end point analyses and post hoc analyses of outcomes stratified by Trop-2 expression and human epidermal growth factor receptor 2 status are reported. Updated safety analyses are provided.In this final analysis, SG (n = 267) improved median progression-free survival (PFS; 4.8 v 1.7 months; hazard ratio (HR), 0.41 [95% CI, 0.33 to 0.52]) and median overall survival (OS; 11.8 v 6.9 months; HR, 0.51 [95% CI, 0.42 to 0.63]) over TPC (n = 262). SG improved PFS over TPC in each Trop-2 expression quartile (n = 168); a trend was observed for improved OS across quartiles. Overall, SG had a manageable safety profile, with ≤5% of treatment-related discontinuations because of adverse events and no treatment-related deaths. The safety profile was consistent across all subgroups.These data confirm the clinical benefit of SG over chemotherapy, reinforcing SG as an effective treatment option in patients with mTNBC in the second line or later.

Background: Despite advances in the treatment of early triple-negative breast cancer (TNBC), patients with residual invasive disease after neoadjuvant therapy have a high risk of disease recurrence and worse survival outcomes than those who have pathological complete response (pCR). Improving outcomes in early TNBC remains an unmet need requiring new adjuvant treatment approaches. Datopotamab deruxtecan (Dato-DXd) is an antibody-drug conjugate comprising a humanized anti-trophoblast cell-surface antigen 2 immunoglobulin G1 (IgG1) monoclonal antibody attached via a plasma-stable, cleavable linker to a potent topoisomerase I inhibitor payload, with activity observed in advanced TNBC., Objectives: TROPION-Breast03 is an ongoing phase III study evaluating the efficacy and safety of Dato-DXd alone or combined with durvalumab versus standard-of-care therapy as adjuvant treatment in patients with stage I-III TNBC with residual invasive disease at surgical resection following neoadjuvant treatment., Methods and Design: Eligible patients, aged ⩾18 years, will be randomized in a 2:1:2 ratio to receive Dato-DXd [6 mg/kg intravenously (IV) every 3 weeks (Q3W); eight cycles] and durvalumab (1120 mg IV Q3W; nine cycles), Dato-DXd monotherapy (6 mg/kg IV Q3W), or investigator's choice of therapy (ICT; capecitabine, pembrolizumab, or capecitabine and pembrolizumab). The primary endpoint is invasive disease-free survival (iDFS) for Dato-DXd and durvalumab versus ICT. Key secondary endpoints include safety, distant disease-free survival, and overall survival for Dato-DXd and durvalumab versus ICT and iDFS for Dato-DXd monotherapy versus ICT., Ethics: TROPION-Breast03 will be approved by the independent ethics committees or institutional review boards at each study site. All study participants will provide written informed consent., Discussion: TROPION-Breast03 will help define the potential role of Dato-DXd in the treatment of patients with early-stage TNBC who do not have pCR after neoadjuvant therapy., Trial Registration: ClinicalTrials.gov identifier: NCT05629585 (registration date: 29 November 2022)., Competing Interests: A.B. reports consulting fees from Pfizer, Novartis, Genentech, Merck, Radius Health, Immunomedics/Gilead, Sanofi, Daiichi Pharma/AstraZeneca, Phillips, Eli Lilly, and Foundation Medicine; grants or funds from Genentech, Novartis, Pfizer, Merck, Sanofi, Radius Health, Immunomedics/Gilead, Daiichi Pharma/AstraZeneca, and Eli Lilly. L.P. reports membership on the board of directors for the HOPE Foundation; consulting fees from Pfizer, AstraZeneca, Merck, Novartis, Bristol Myers Squibb, GlaxoSmithKline, Roche/Genentech, Personalis, Daiichi, Natera, and Exact Sciences; and institutional research funding from Seagen, GlaxoSmithKline, AstraZeneca, Merck, Pfizer, and Bristol Myers Squibb. K.A. reports institutional research funding from Quantum Leap (I-SPY 2); and non-financial conflicts with IDMC (member) and Seattle Genetics. EMC reports consulting fees from Pfizer, MSD, Gilead, Roche, Eli Lilly, Daiichi-Sankyo, Novartis, and AstraZeneca; and institutional research funding from Roche. S.-A.I. reports advisory council or committee participation with AstraZeneca, Novartis, Hanmi, Pfizer, Eisai, Roche, Eli Lilly, GlaxoSmithKline, MSD, Daiichi-Sankyo, Idience, and Bertis; and grants or funds from AstraZeneca, Pfizer, Eisai, Roche, Daewoong Pharm, Boryung Pharm, and Daiichi-Sankyo. D.H. declares no conflicts of interest. K.K. reports consulting fees from Merck, Eli Lilly, Novartis, AstraZeneca, Roche/Genentech, Immunomedics, Seattle Genetics, Oncosec, 4D pharma, Daiichi-Sankyo, Puma Biotechnology, Mersna, Menarini Silicon Biosystems, Myovant Sciences, and Takeda; and grants or funds from Novartis, Ascentage, Roche/Genentech, Eli Lilly, Seattle Genetics, AstraZeneca, and Daiichi-Sankyo. C.I. reports consulting fees from Genentech, Puma Biotechnology, Seattle Genetics, AstraZeneca, Novartis, Pfizer, ION, and Gilead; institutional research funding from Tesaro/GlaxoSmithKline, Seattle Genetics, Pfizer, AstraZeneca, Bristol Myers Squibb, Genentech, and Novartis; and other financial relationships with Wolters Kluwer (UptoDate) and McGraw Hill (Goodman and Gillman). D.L. reports advisory council or committee participation with MSD, Seagen, Novartis, Eli Lilly, AstraZeneca, and Exact Sciences; honoraria from MSD, Seagen, Pfizer, Novartis, Eli Lilly, AstraZeneca, Roche, Exact Sciences, and Daiichi-Sankyo; and consulting fees from MSD and AstraZeneca. L.T. reports advisory council or committee participation with AstraZeneca, Daichii-Sankyo, MSD, Eli Lilly, Novartis, and Pfizer; consulting fees from AstraZeneca, Daiichi-Sankyo, MSD, Novartis, and Pfizer; grants or funds from Novartis; and provision of educational support for Roche, Pfizer, AstraZeneca, and Gilead. E.T. reports honoraria from Daiichi-Sankyo, AstraZeneca, and Eli Lilly. J.W. reports research funding from the National Natural Science Foundation and F. Hoffmann-La Roche Ltd; committee participation with Eli Lilly, AstraZeneca; honoraria from Novartis. H.D. reports employment by AstraZeneca and ownership of stock/shares in AstraZeneca. W.B. declares no conflicts of interest. R.K. reports employment by AstraZeneca. M.M. reports employment by AstraZeneca and ownership of stock/shares in AstraZeneca. N.H. reports membership on the board of directors of the West German Study Group (WSG); status as the ESMO Director of Education; honoraria from Amgen, AstraZeneca, Daiichi-Sankyo, EPG Communication, Gilead, Eli Lilly, Medscape, MSD, Novartis, Pierre-Fabre, Pfizer, Roche, Sandoz, Sanofi, Seagen, Springer, Viatris, and Zuellig Pharma; consulting fees from Gilead, Roche, Sandoz, Sanofi, and Seagen. P.S. reports consulting fees from Pfizer, Merck, Gilead, Genzyme (Sanofi), Novartis, AstraZeneca, and GlaxoSmithKline; institutional research funding from Novartis, Merck, and Gilead; and royalties from UpToDate., (© The Author(s), 2024.)

In this post hoc analysis of the ASCENT study, we compared outcomes with sacituzumab govitecan (SG) vs single-agent chemotherapy in clinically important subgroups of patients with metastatic triple-negative breast cancer (mTNBC). Patients with mTNBC refractory to/relapsing after ≥2 prior chemotherapies (≥1 in the metastatic setting) were randomized 1:1 to receive SG or treatment of physician's choice (TPC) until unacceptable toxicity/progression. The primary endpoint was progression-free survival (PFS) per RECIST 1.1 by central review in patients without brain metastases. Patients with brain metastases were allowed if metastases were stable ≥4 weeks. In the intention-to-treat (ITT) population, 19% of patients were age ≥65 years; 12% were Black, and 12% had brain metastases. SG improved PFS and overall survival (OS), respectively, vs TPC in patients age ≥65 years (7.1 vs 2.4 months and 14.7 vs 8.9 months), or of Black race (5.4 vs 2.2 months and 13.8 vs 8.5 months), consistent with outcomes in the ITT population. Patients with brain metastases had numerically higher median PFS with SG vs TPC, but median OS was similar between treatment groups. SG was well tolerated and had a manageable safety profile consistent with the full safety population across all subgroups; neutropenia and diarrhea were the most common treatment-emergent adverse events. These findings confirm the meaningful clinical benefit of SG vs standard chemotherapy in patient subgroups with high unmet needs. SG should be considered an effective and safe treatment option for patients with mTNBC eligible for second-line or later therapy. ClinicalTrials.gov Number: NCT02574455., (© 2024. The Author(s).)

Despite widespread utilization of immunotherapy, treating immune-cold tumors remains a challenge. Multiomic analyses and experimental validation identified the OTUD4/CD73 proteolytic axis as a promising target in treating immune-suppressive triple negative breast cancer (TNBC). Mechanistically, deubiquitylation of CD73 by OTUD4 counteracted its ubiquitylation by TRIM21, resulting in CD73 stabilization inhibiting tumor immune responses. We further demonstrated the importance of TGF-β signaling for orchestrating the OTUD4/CD73 proteolytic axis within tumor cells. Spatial transcriptomics profiling discovered spatially resolved features of interacting malignant and immune cells pertaining to expression levels of OTUD4 and CD73. In addition, ST80, a newly developed inhibitor, specifically disrupted proteolytic interaction between CD73 and OTUD4, leading to reinvigoration of cytotoxic CD8+ T cell activities. In preclinical models of TNBC, ST80 treatment sensitized refractory tumors to anti-PD-L1 therapy. Collectively, our findings uncover what we believe to be a novel strategy for targeting the immunosuppressive OTUD4/CD73 proteolytic axis in treating immune-suppressive breast cancers with the inhibitor ST80.

Improving the prognosis for patients with metastatic HR+/HER2- breast cancer remains an unmet need. Patients with tumors that have progressed on endocrine therapy and/or are not eligible for endocrine therapy had limited treatment options beyond chemotherapy. Antibody-drug conjugates are a novel and promising treatment class in this setting. Datopotamab deruxtecan (Dato-DXd) consists of a TROP2-directed humanized IgG1 monoclonal antibody attached via a serum-stable cleavable linker to a topoisomerase I inhibitor payload. TROPION-Breast01 is an ongoing phase III study that is evaluating the efficacy and safety of Dato-DXd compared with investigator's choice of standard-of-care chemotherapy in patients with inoperable or metastatic HR+/HER2- breast cancer who have received one or two prior lines of systemic chemotherapy in the inoperable or metastatic setting. Clinical Trial Registration: NCT05104866 (ClinicalTrials.gov).

Background: Chemotherapy-induced peripheral neuropathy (CIPN) is a common and debilitating adverse effect of taxane therapy. Small non-randomized studies in patients with early-stage breast cancer (ESBC) suggest both cryotherapy and compression therapy may prevent CIPN. It is unknown which is more effective., Methods: We conducted a randomized phase IIB adaptive sequential selection trial of cryotherapy vs. compression therapy vs. placebo ("loose" gloves/socks) during taxane chemotherapy. Participants were randomized in triplets. Garments were worn for 90-120 min, beginning 15 min prior and continuing for 15 min following the infusion. The primary goal was to select the best intervention based on a Levin-Robbins-Leu sequential selection procedure. The primary endpoint was a < 5-point decrease in the Functional Assessment of Cancer Therapy Neurotoxicity (FACT-NTX) at 12 weeks. An arm was eliminated if it had four or more fewer successes than the currently leading arm. Secondary endpoints included intervention adherence and patient-reported comfort/satisfaction., Results: Between April 2019 and April 2021, 63 patients were randomized (cryotherapy (20); compression (22); placebo (21)). Most patients (60.3%) were treated with docetaxel. The stopping criterion was met after the 17th triplet (n = 51) was evaluated; success at 12 weeks occurred in 11 (64.7%) on compression therapy, 7 (41.1%) on cryotherapy, and 7 (41.1%) on placebo. Adherence to the intervention was lowest with cryotherapy (35.0%) compared to compression (72.7%) and placebo (76.2%)., Conclusion: Compression therapy was the most effective intervention in this phase IIB selection trial to prevent CIPN and was well tolerated. Compression therapy for the prevention of CIPN should be evaluated in a phase III study., Clinical Trial Registration: ClinicaTrials.gov Identifier: NCT03873272., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Approved antibody-drug conjugates (ADCs) for HER2-positive breast cancer include trastuzumab emtansine and trastuzumab deruxtecan. To develop a differentiated HER2 ADC, we chose an antibody that does not compete with trastuzumab or pertuzumab for binding, conjugated to a reduced potency PBD (pyrrolobenzodiazepine) dimer payload. PBDs are potent cytotoxic agents that alkylate and cross-link DNA. In our study, the PBD dimer is modified to alkylate, but not cross-link DNA. This HER2 ADC, DHES0815A, demonstrates in vivo efficacy in models of HER2-positive and HER2-low cancers and is well-tolerated in cynomolgus monkey safety studies. Mechanisms of action include induction of DNA damage and apoptosis, activity in non-dividing cells, and bystander activity. A dose-escalation study (ClinicalTrials.gov: NCT03451162) in patients with HER2-positive metastatic breast cancer, with the primary objective of evaluating the safety and tolerability of DHES0815A and secondary objectives of characterizing the pharmacokinetics, objective response rate, duration of response, and formation of anti-DHES0815A antibodies, is reported herein. Despite early signs of anti-tumor activity, patients at higher doses develop persistent, non-resolvable dermal, ocular, and pulmonary toxicities, which led to early termination of the phase 1 trial., (© 2024. The Author(s).)

Opinion Statement: Hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER-2-) metastatic breast cancer (MBC) is the most common subtype of breast cancer. Due to therapeutic advances with molecularly targeted therapies, the prognosis for patients with metastatic disease has improved significantly. The advent of CDK4/6 inhibitors (CDK4/6i) has changed the treatment paradigm for patients with HR+HER2-MBC. CDK4/6i allowed for marked improvement in overall survival, delaying the time to chemotherapy initiation, and improved quality of life for our patients. Efforts are now focused on the best approach(es) for patients after progression on CDK4/6i. Can we further harness the benefit of CDK4/6i in novel combinations at the time of progression? Should we continue CDK4/6i or proceed other novel agents or endocrine therapies? As we advance our treatment strategies for HR+HER2-MBC, there is no longer a one-size-fits-all model, but instead a multifaceted and personalized approach lending to improved outcomes for our patients., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Purpose: Cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) with endocrine therapy (ET) improves progression-free survival (PFS) and overall survival (OS) in hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC). Although preclinical and clinical data demonstrate a benefit in changing ET and continuing a CDK4/6i at progression, no randomized prospective trials have evaluated this approach., Methods: In this investigator-initiated, phase II, double-blind placebo-controlled trial in patients with HR+/HER2- MBC whose cancer progressed during ET and CDK4/6i, participants switched ET (fulvestrant or exemestane) from ET used pre-random assignment and randomly assigned 1:1 to the CDK4/6i ribociclib versus placebo. PFS was the primary end point, defined as time from random assignment to disease progression or death. Assuming a median PFS of 3.8 months with placebo, we had 80% power to detect a hazard ratio (HR) of 0.58 (corresponding to a median PFS of at least 6.5 months with ribociclib) with 120 patients randomly assigned using a one-sided log-rank test and significance level set at 2.5%., Results: Of the 119 randomly assigned participants, 103 (86.5%) previously received palbociclib and 14 participants received ribociclib (11.7%). There was a statistically significant PFS improvement for patients randomly assigned to switched ET plus ribociclib (median, 5.29 months; 95% CI, 3.02 to 8.12 months) versus switched ET plus placebo (median, 2.76 months; 95% CI, 2.66 to 3.25 months) HR, 0.57 (95% CI, 0.39 to 0.85); P = .006. At 6 and 12 months, the PFS rate was 41.2% and 24.6% with ribociclib, respectively, compared with 23.9% and 7.4% with placebo., Conclusion: In this randomized trial, there was a significant PFS benefit for patients with HR+/HER2- MBC who switched ET and received ribociclib compared with placebo after previous CDK4/6i and different ET.

Importance: Little is known about regional nodal irradiation (RNI) practice patterns or rates of locoregional recurrence (LRR) with and without RNI in patients with limited nodal disease and favorable biology treated with modern surgical and systemic therapy, including approaches that de-escalate those latter treatments., Objective: To investigate how often patients with low-recurrence score breast cancer with 1 to 3 nodes involved receive RNI, incidence and predictors of LRR, and associations between locoregional therapy and disease-free survival., Design, Setting, and Participants: In this secondary analysis of the SWOG S1007 trial, patients with hormone receptor-positive, ERBB2-negative breast cancer, and a Oncotype DX 21-gene Breast Recurrence Score assay result of no more than 25, were randomized to endocrine therapy alone vs chemotherapy then endocrine therapy. Prospectively collected radiotherapy information was collected from 4871 patients treated in diverse settings. Data were analyzed June 2022 to April 2023., Exposure: Receipt of RNI (targeting at least the supraclavicular region)., Main Outcome(s) and Measure(s): Cumulative incidence of LRR was calculated by locoregional treatment received. Analyses were assessed for associations between invasive disease-free survival (IDFS) and locoregional therapy, adjusted for menopausal status, treatment group, recurrence score, tumor size, nodes involved, and axillary surgery. Radiotherapy information was recorded in the first year after randomization, so survival analyses were landmarked as starting at 1 year among those still at risk., Results: Of 4871 female patients (median [range] age, 57 [18-87] years) with radiotherapy forms, 3947 (81.0%) reported radiotherapy receipt. Of 3852 patients who received radiotherapy and had complete information on targets, 2274 (59.0%) received RNI. With a median follow-up of 6.1 years, the cumulative incidence of LRR by 5 years was 0.85% among patients who received breast-conserving surgery and radiotherapy with RNI; 0.55% after breast-conserving surgery with radiotherapy without RNI; 0.11% after mastectomy with postmastectomy radiotherapy; and 1.7% after mastectomy without radiotherapy. Similarly low LRR was observed within the group assigned to endocrine therapy without chemotherapy. The rate of IDFS did not differ by RNI receipt (premenopausal: hazard ratio [HR], 1.03; 95% CI, 0.74-1.43; P = .87; postmenopausal: HR, 0.85; 95% CI, 0.68-1.07; P = .16)., Conclusions and Relevance: In this secondary analysis of a clinical trial, RNI use was divided in the setting of biologically favorable N1 disease, and rates of LRR were low even in patients who did not receive RNI. Disease-free survival was not associated with RNI receipt; omission of chemotherapy among patients similar to those enrolled in the S1007 trial is not an independent indication for use of RNI.

Purpose: Cyclin Dependent Kinase 4 & 6 inhibitors (CDK4 & 6i) have transformed the management of HR+, HER2- metastatic breast cancer (MBC); however, the optimal sequence of these treatments and other systemic therapies for MBC remains unclear., Methods: This study analyzed electronic medical records from the ConcertAI Oncology Dataset. US patients who received abemaciclib and at least one other systemic line of therapy (LOT) for HR+, HER2- MBC were eligible. Treatment sequences were grouped, and data for two pairs of groups are presented herein (N = 397): Group 1 (1L CDK4 & 6i to 2L CDK4 & 6i) vs. Group 2 (1L CDK4 & 6i to 2L non-CDK4 & 6i), and Group 3 (2L CDK4 & 6i to 3L CDK4 & 6i) vs. Group 4 (2L CDK4 & 6i to 3L non-CDK4 & 6i). Time-to-event outcomes (PFS and PFS-2) were analyzed using Kaplan-Meier method and Cox proportional hazard regression., Results: In the total cohort of 690 patients, the most prevalent sequence was 1L CDK4 & 6i to 2L CDK4 & 6i (n = 165). For the 397 patients across Groups 1-4, sequential CDK4 & 6i demonstrated numerically longer PFS and PFS-2 versus non-sequential CDK4 & 6i. Adjusted results demonstrate that patients in Group 1 demonstrated significantly longer PFS (p = 0.05) versus Group 2., Conclusions: Although retrospective and hypothesis-generating, these data demonstrate numerically longer outcomes in the subsequent LOT associated with sequential CDK4 & 6i treatment., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)