VERITAC-2: a Phase III study of vepdegestrant, a PROTAC ER degrader, versus fulvestrant in ER+/HER2- advanced breast cancer.

Vepdegestrant (ARV-471) is an oral PROTAC ER degrader that binds an E3 ubiquitin ligase and ER to directly trigger ubiquitination of ER and its subsequent proteasomal degradation. In a first-in-human Phase I/II study, vepdegestrant monotherapy was well tolerated with clinical activity in pretreated patients with ER+/HER2- advanced breast cancer. The global, randomized Phase III VERITAC-2 study compares efficacy and safety of vepdegestrant versus fulvestrant in adults with ER+/HER2- advanced breast cancer after treatment with a CDK4/6 inhibitor plus endocrine therapy. Progression-free survival by blinded independent central review (primary end point) will be assessed in the intention-to-treat population and ESR1 mutation-positive subpopulation. Secondary end points include overall survival, tumor response, safety, pharmacokinetics, patient-reported outcomes, and circulating tumor DNA biomarkers.Clinical trial registration: NCT05654623 (ClinicalTrials.gov).

VERITAC-2 is a clinical trial comparing vepdegestrant, a new drug that degrades estrogen receptors, to an existing treatment called fulvestrant in patients with ER+/HER2- advanced breast cancer: Estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-) breast cancer grows in response to estrogen, a hormone in the body, and has low levels or no HER2 protein. People living with ER+/HER2- advanced breast cancer that has grown, spread to another part of the body, or cannot be removed by surgery are often treated with cyclin-dependent kinase (CDK) 4/6 inhibitors and endocrine therapies, but their cancer may get worse on these treatments and new treatments are needed. Fulvestrant, an endocrine therapy that attaches to estrogen receptors, lowers estrogen's effect on tumors and can slow or stop cancer growth. Vepdegestrant, a new medicine being tested for ER+ breast cancer, is a PROteolysis TArgeting Chimera (PROTAC) protein degrader that attaches to estrogen receptors and causes them to be tagged for removal by the cell's natural protein disposal system. By removing estrogen receptors, vepdegestrant may cause tumors to stop growing or shrink.This paper describes the Phase III VERITAC-2 clinical study comparing vepdegestrant versus fulvestrant in people living with ER+/HER2- advanced breast cancer previously treated with a CDK4/6 inhibitor and endocrine therapy.Patients will be randomly assigned to receive vepdegestrant (a pill taken once daily by mouth) or fulvestrant (a shot given into the muscle). The purpose of the study is to find out how long people live without their cancer getting worse with vepdegestrant or fulvestrant. VERITAC-2 will also look at how long people live during the study, side effects people may experience, and the overall well-being of people throughout the study.

Trastuzumab deruxtecan versus trastuzumab emtansine in HER2-positive metastatic breast cancer: long-term survival analysis of the DESTINY-Breast03 trial.

Trastuzumab deruxtecan (T-DXd) demonstrated significantly improved efficacy over trastuzumab emtansine (T-DM1) in DESTINY-Breast03 (median follow-up, 28 months). We report updated efficacy and safety analyses, including secondary and exploratory efficacy endpoints (median follow-up, 41 months) of DESTINY-Breast03. Patients with advanced HER2-positive metastatic breast cancer previously treated with taxane and trastuzumab were randomized to T-DXd (5.4 mg per kg (261 patients)) or T-DM1 (3.6 mg per kg (263 patients)). The primary endpoint was progression-free survival (PFS) by blinded independent central review and was previously reported. The key secondary endpoint was overall survival (OS). Other secondary endpoints included objective response rate, duration of response and PFS (all by investigator assessment) and safety. At data cutoff, 20 November 2023, median PFS by investigator assessment was 29.0 versus 7.2 months (hazard ratio (HR), 0.30; 95% confidence interval (CI), 0.24-0.38), the 36-month PFS rate was 45.7% versus 12.4% and median OS was 52.6 versus 42.7 months (HR, 0.73; 95% CI, 0.56-0.94) with T-DXd versus T-DM1, respectively. Treatment-emergent adverse events were consistent with the previous analyses. No new instances of grade ≥3 interstitial lung disease or pneumonitis occurred (all grade rate, 16.7% (T-DXd) versus 3.4% (T-DM1)). With longer follow-up, T-DXd continued to demonstrate superior efficacy over T-DM1 with a manageable safety profile. ClinicalTrials.gov registration: NCT03529110 .

Randomized Phase III Study of Amcenestrant Plus Palbociclib Versus Letrozole Plus Palbociclib in Estrogen Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer: Primary Results From AMEERA-5.

PURPOSE: AMEERA-5 investigated amcenestrant (oral selective estrogen receptor [ER] degrader) plus palbociclib versus letrozole plus palbociclib as first-line treatment for ER-positive/human epidermal growth factor receptor 2-negative (ER+/HER2-) advanced/metastatic breast cancer (aBC). MATERIALS AND METHODS: In AMEERA-5 (ClinicalTrials.gov identifier: NCT04478266), a double-blind, double-dummy, international phase III trial, adult pre-/post-menopausal women and men without previous systemic therapy for ER+/HER2- aBC were randomly assigned 1:1 to amcenestrant 200 mg once daily + standard palbociclib dosage (125 mg once daily, 21 days on/7 days off) or letrozole 2.5 mg once daily + standard palbociclib dosage, stratified by de novo metastatic disease, postmenopausal women, and visceral metastasis. The primary end point was progression-free survival (PFS), compared using a stratified log-rank test with one-sided type I error rate of 2.5%. Secondary end points included overall survival (key secondary), pharmacokinetics, and safety. RESULTS: Between October 14, 2020, and December 2, 2021, 1,068 patients were randomly assigned to amcenestrant + palbociclib (N = 534) or letrozole + palbociclib (N = 534). At the interim analysis (median follow-up 8.4 months), the stratified hazard ratio for PFS was 1.209 (95% CI, 0.939 to 1.557; one-sided P value = .9304); therefore, the study was stopped for futility. The 6-month PFS rate was 82.7% (95% CI, 79.0 to 85.8) with amcenestrant + palbociclib versus 86.9% (95% CI, 83.5 to 89.6) with letrozole + palbociclib. In the amcenestrant + palbociclib versus letrozole + palbociclib groups, treatment-emergent adverse events (any grade) occurred in 85.6% versus 85.4% of patients and grade ≥3 events in 46.3% versus 60.8%, respectively. CONCLUSION: The AMEERA-5 study was discontinued on the basis of the recommendation of the data monitoring committee at the interim futility analysis. No new safety signals were identified.

Subgroup analyses from the phase 3 ASCENT study of sacituzumab govitecan in metastatic triple-negative breast cancer.

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.

Final Results From the Randomized Phase III ASCENT Clinical Trial in Metastatic Triple-Negative Breast Cancer and Association of Outcomes by Human Epidermal Growth Factor Receptor 2 and Trophoblast Cell Surface Antigen 2 Expression.

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.

Type I interferons, inflammation, and fatigue in a longitudinal RNA study of women with breast cancer.

BACKGROUND: Fatigue is a common side effect of cancer and its treatment and is thought to be driven in part by activation of the proinflammatory cytokine network. However, the cellular and molecular underpinnings of cancer-related fatigue (CRF) have not been determined, nor have immune pathways beyond inflammation been carefully investigated. The goal of this study was to examine the association between CRF and activation of canonical proinflammatory gene regulation pathways and Type I interferon (IFN) signaling pathways in breast cancer patients during and after treatment. METHODS: Women diagnosed with early-stage breast cancer (n = 181) completed assessments before and after treatment with radiation and/or chemotherapy and at 6, 12, and 18-month post-treatment follow-ups. Assessments included self-reported fatigue (Multidimensional Fatigue Symptom Inventory - Short Form) and expression of pre-specified sets of Type I IFN and pro-inflammatory immune response genes determined from mRNA sequencing of PBMCs. Mixed effect linear models examined changes in fatigue and immune gene expression over time and tested the hypothesis that fatigue would be associated with increased expression of Type I IFN and inflammatory response genes. RESULTS: There were significant changes in fatigue and immune gene expression across the assessment period; all measures increased from pre- to post-treatment but showed diverging patterns over the follow-up, with declines in fatigue and persistent elevations in Type I IFN and proinflammatory gene expression. In mixed effect linear models, expression of Type I IFN response genes was elevated in association with fatigue across the assessment period, from pre-treatment to 18-month follow-up. In contrast, pro-inflammatory gene expression was associated with fatigue only at 6, 12, and 18-month follow-ups. Analyses controlling for changes in leukocyte subsets continued to show a significant association between fatigue and Type I IFN gene expression but reduced the time-dependent association with pro-inflammatory gene expression to non-significant. CONCLUSIONS: Results revealed unexpected complexity in the immune underpinnings of CRF and identify a novel role for IFN signaling as a robust contributor to this symptom before, during, and after treatment. Pro-inflammatory gene expression emerged as a predictor of fatigue later in the cancer trajectory, and that effect was primarily accounted for by a concurrent increase in monocyte prevalence.

Landscape of baseline and acquired genomic alterations in circulating tumor DNA with abemaciclib alone or with endocrine therapy in advanced breast cancer.

PURPOSE: To identify potential predictors of response and resistance mechanisms in patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC) treated with the CDK4/6 inhibitor abemaciclib +/- endocrine therapy (ET), baseline and acquired genomic alterations in circulating tumor DNA (ctDNA) were analyzed and associated with clinical outcomes. PATIENTS AND METHODS: MONARCH 3: postmenopausal women with HR+, HER2- ABC and no prior systemic therapy in the advanced setting were randomized to abemaciclib or placebo plus nonsteroidal aromatase inhibitor (NSAI). nextMONARCH: women with HR+, HER2- metastatic breast cancer that progressed on/after prior ET and chemotherapy were randomized to abemaciclib alone (two doses) or plus tamoxifen. Baseline and end-of-treatment plasma samples from patients in MONARCH 3 and nextMONARCH (monotherapy arms) were analyzed to identify somatic genomic alterations. Association between genomic alterations and median progression-free survival (mPFS) was assessed. RESULTS: Most patients had ≥1 genomic alteration detected in baseline ctDNA. In MONARCH 3, abemaciclib+NSAI was associated with improved mPFS versus placebo+NSAI, regardless of baseline alterations. ESR1 alterations were less frequently acquired in the abemaciclib+NSAI arm than placebo+NSAI. Acquired alterations potentially associated with resistance to abemaciclib +/- NSAI included RB1 and MYC. CONCLUSIONS: In MONARCH 3, certain baseline ctDNA genomic alterations were prognostic for ET but not predictive of abemaciclib response. Further studies are warranted to assess whether ctDNA alterations acquired during abemaciclib treatment differ from other CDK4/6 inhibitors. Findings are hypothesis-generating, further exploration is warranted into mechanisms of resistance to abemaciclib and ET.

Genomic analysis of advanced breast cancer tumors from talazoparib-treated gBRCA1/2mut carriers in the ABRAZO study.

These analyses explore the impact of homologous recombination repair gene mutations, including BRCA1/2 mutations and homologous recombination deficiency (HRD), on the efficacy of the poly(ADP-ribose) polymerase (PARP) inhibitor talazoparib in the open-label, two-cohort, Phase 2 ABRAZO trial in germline BRCA1/2-mutation carriers. In the evaluable intent-to-treat population (N = 60), 58 (97%) patients harbor ≥1 BRCA1/2 mutation(s) in tumor sequencing, with 95% (53/56) concordance between germline and tumor mutations, and 85% (40/47) of evaluable patients have BRCA locus loss of heterozygosity indicating HRD. The most prevalent non-BRCA tumor mutations are TP53 in patients with BRCA1 mutations and PIK3CA in patients with BRCA2 mutations. BRCA1- or BRCA2-mutated tumors show comparable clinical benefit within cohorts. While low patient numbers preclude correlations between HRD and efficacy, germline BRCA1/2 mutation detection from tumor-only sequencing shows high sensitivity and non-BRCA genetic/genomic events do not appear to influence talazoparib sensitivity in the ABRAZO trial.ClinicalTrials.gov identifier: NCT02034916.

Neoadjuvant palbociclib plus either giredestrant or anastrozole in oestrogen receptor-positive, HER2-negative, early breast cancer (coopERA Breast Cancer): an open-label, randomised, controlled, phase 2 study.

BACKGROUND: The development of more potent selective oestrogen receptor antagonists and degraders (SERDs) that can be orally administered could help to address the limitations of current endocrine therapies. We report the primary and final analyses of the coopERA Breast Cancer study, designed to test whether giredestrant, a highly potent, non-steroidal, oral SERD, would show a stronger anti-proliferative effect than anastrozole after 2 weeks for oestrogen receptor-positive, HER2-negative, untreated early breast cancer. METHODS: In this open-label, randomised, controlled, phase 2 study, postmenopausal women were eligible if they were aged 18 years or older; had clinical T stage (cT)1c to cT4a-c (≥1·5 cm within cT1c) oestrogen receptor-positive, HER2-negative, untreated early breast cancer; an Eastern Cooperative Oncology Group performance status of 0-1; and baseline Ki67 score of at least 5%. The study was conducted at 59 hospital or clinic sites in 11 countries globally. Participants were randomly assigned (1:1) to giredestrant 30 mg oral daily or anastrozole 1 mg oral daily on days 1-14 (window-of-opportunity phase) via an interactive web-based system with permuted-block randomisation with block size of four. Randomisation was stratified by cT stage, baseline Ki67 score, and progesterone receptor status. A 16-week neoadjuvant phase comprised the same regimen plus palbociclib 125 mg oral daily on days 1-21 of a 28-day cycle, for four cycles. The primary endpoint was geometric mean relative Ki67 score change from baseline to week 2 in patients with complete central Ki67 scores at baseline and week 2 (window-of-opportunity phase). Safety was assessed in all patients who received at least one dose of study drug. The study is registered with ClinicalTrials.gov (NCT04436744) and is complete. FINDINGS: Between Sept 4, 2020, and June 22, 2021, 221 patients were enrolled and randomly assigned to the giredestrant plus palbociclib group (n=112; median age 62·0 years [IQR 57·0-68·5]) or anastrozole plus palbociclib group (n=109; median age 62·0 [57·0-67·0] years). 15 (7%) of 221 patients were Asian, three (1%) were Black or African American, 194 (88%) were White, and nine (4%) were unknown races. At data cutoff for the primary analysis (July 19, 2021), the geometric mean relative reduction of Ki67 from baseline to week 2 was -75% (95% CI -80 to -70) with giredestrant and -67% (-73 to -59) with anastrozole (p=0·043), meeting the primary endpoint. At the final analysis (data cutoff Nov 24, 2021), the most common grade 3-4 adverse events were neutropenia (29 [26%] of 112 in the giredestrant plus palbociclib group vs 29 [27%] of 109 in the anastrozole plus palbociclib group) and decreased neutrophil count (17 [15%] vs 16 [15%]). Serious adverse events occurred in five (4%) patients in the giredestrant plus palbociclib group and in two (2%) patients in the anastrozole plus palbociclib group. There were no treatment-related deaths. One patient died due to an adverse event in the giredestrant plus palbociclib group (myocardial infarction). INTERPRETATION: Giredestrant offers encouraging anti-proliferative and anti-tumour activity and was well tolerated, both as a single agent and in combination with palbociclib. Results justify further investigation in ongoing trials. FUNDING: F Hoffmann-La Roche.

Molecular Residual Disease in Breast Cancer: Detection and Therapeutic Interception.

Breast cancer remains a leading cause of cancer-related death in women despite screening and therapeutic advances. Early detection allows for resection of local disease; however, patients can develop metastatic recurrences years after curative treatment. There is no reliable blood-based monitoring after curative therapy, and radiographic evaluation for metastatic disease is performed only in response to symptoms. Advances in circulating tumor DNA (ctDNA) assays have allowed for a potential option for blood-based monitoring. The detection of ctDNA in the absence of overt metastasis or recurrent disease indicates molecular evidence of cancer, defined as molecular residual disease (MRD). Multiple studies have shown that MRD detection is strongly associated with disease recurrence, with a lead time prior to clinical evidence of recurrence of many months. Importantly, it is still unclear whether treatment changes in response to ctDNA detection will improve outcomes. There are currently ongoing trials evaluating the efficacy of therapy escalation in the setting of MRD, and these studies are being conducted in all major breast cancer subtypes. Additional therapies under study include CDK4/6 inhibitors, PARP inhibitors, HER2-targeted therapies, and immunotherapy. This review will summarize the underlying scientific principles of various MRD assays, their known prognostic roles in early breast cancer, and the ongoing clinical trials assessing the efficacy of therapy escalation in the setting of MRD.

NCCN Guidelines® Insights: Breast Cancer, Version 4.2023.

The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Breast Cancer address all aspects of management for breast cancer. The treatment landscape of metastatic breast cancer is evolving constantly. The therapeutic strategy takes into consideration tumor biology, biomarkers, and other clinical factors. Due to the growing number of treatment options, if one option fails, there is usually another line of therapy available, providing meaningful improvements in survival. This NCCN Guidelines Insights report focuses on recent updates specific to systemic therapy recommendations for patients with stage IV (M1) disease.

Real-World First-Line Use of Pertuzumab With Different Taxanes for Human Epidermal Growth Factor Receptor 2-Positive Metastatic Breast Cancer: A Comparative Effectiveness Study Using US Electronic Health Records.

PURPOSE: On the basis of the results from CLEOPATRA, pertuzumab plus trastuzumab and chemotherapy is the first-line standard of care for human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC). However, discrepancies have been reported between clinical trial and real-world outcomes. We report real-world outcomes for patients with HER2-positive MBC treated with first-line pertuzumab plus trastuzumab and a taxane in routine clinical practice in the United States. METHODS: A retrospective analysis was conducted using electronic health record-derived deidentified data from the Flatiron Health database. Patients were grouped according to the first taxane received (paclitaxel/nab-paclitaxel or docetaxel). Median real-world progression-free survival (rwPFS) and overall survival (rwOS) was estimated using Kaplan-Meier methodology. Subgroup analyses were conducted in patients treated with docetaxel who met CLEOPATRA's key eligibility criteria. RESULTS: We included 1,065 patients; 313 patients received paclitaxel/nab-paclitaxel and 752 received docetaxel. Patients who received paclitaxel/nab-paclitaxel were older, had a worse Eastern Cooperative Oncology Group Performance Status, and had more recurrent metastatic disease compared with the docetaxel group. After adjustment for potential confounders, similar median rwPFS (inverse probability of treatment weighted average treatment effect for the treated [IPTW-ATT] hazard ratio [HR], 1.09; 95% CI, 0.9 to 1.3; P = .365) and rwOS (IPTW-ATT HR, 1.23; 95% CI, 0.96 to 1.58; P = .101) was observed between treatment groups. In the subgroup of CLEOPATRA-eligible patients, median rwPFS and rwOS were 16.9 months and 57.8 months, respectively. CONCLUSION: There was no statistically significant difference in real-world outcomes between patients treated with paclitaxel/nab-paclitaxel and those treated with docetaxel. Selecting patients using key CLEOPATRA eligibility criteria resulted in rwPFS and rwOS similar to those observed in CLEOPATRA, highlighting the importance of ensuring similar patient populations when comparing clinical trial and real-world data.

Tumor biomarkers and efficacy in patients treated with trastuzumab emtansine + pertuzumab versus standard of care in HER2-positive early breast cancer: an open-label, phase III study (KRISTINE).

BACKGROUND: KRISTINE is an open-label, phase III study of trastuzumab emtansine + pertuzumab (T-DM1 + P) versus docetaxel + carboplatin + trastuzumab + pertuzumab (TCH + P) in patients with HER2-positive, stage II-III breast cancer. We investigated the association of biomarkers with clinical outcomes in KRISTINE. METHODS: Patients were randomized to receive neoadjuvant T-DM1 + P or TCH + P and assessed for pathologic complete response (pCR; ypT0/is, ypN0). HER2 status (per central assessment), hormone receptor status, PIK3CA mutation status, HER2/HER3 mRNA levels, tumor-infiltrating lymphocyte levels, PD-L1 status, and NanoString data were analyzed. pCR rates by treatment arm were compared across biomarker subgroups. Analyses were descriptive. RESULTS: Biomarker analyses included data from all 444 patients (T-DM1 + P, n = 223; TCH + P, n = 221) enrolled in KRISTINE. Biomarker distribution was balanced across treatment arms. All subgroups with higher HER2 amplification/expression and immune marker levels showed numerically higher pCR rates in both arms. Mutated versus non-mutated PIK3CA tumors were associated with numerically lower pCR rates in the T-DM1 + P arm but not in the TCH + P arm. In a multivariate analysis, Prediction Analysis of Microarray with the 50-gene classifier (PAM50) HER2-enriched subtype, HER2 gene ratio ≥ 4, and PD-L1-positive status positively influenced the pCR rate. Biomarkers associated with lower pCR rates (e.g., low HER2 levels, positive hormone receptor status, mutated PIK3CA) were more likely to co-occur. Dynamic on-treatment biomarker changes were observed. Differences in the treatment effects for T-DM1 + P versus TCH + P were similar to those observed in the intent-to-treat population for the majority of the biomarker subgroups. CONCLUSIONS: Although our biomarker analysis did not identify a subgroup of patients that benefited from neoadjuvant T-DM1 + P versus TCH + P, the data revealed that patients with higher HER2 amplification/expression and immune marker levels had improved response irrespective of treatment arm. These analyses confirm the role of HER2 tumor biology and the immune microenvironment in influencing pCR in the neoadjuvant setting and reaffirm the molecular diversity of HER2-positive breast cancer. TRIAL REGISTRATION: ClinicalTrials.gov NCT02131064. Registered 06 May 2014.

Final findings from the CONTROL trial: Strategies to reduce the incidence and severity of neratinib-associated diarrhea in patients with HER2-positive early-stage breast cancer.

BACKGROUND: Neratinib is an irreversible pan-HER tyrosine kinase inhibitor approved for HER2-positive early-stage and metastatic breast cancer. Diarrhea is the most frequent side effect and the most common reason for early discontinuation. The phase II CONTROL trial investigated antidiarrheal prophylaxis or neratinib dose escalation (DE) for prevention of diarrhea. We present complete study results including final data for two DE strategies. METHODS: Patients who completed trastuzumab-based adjuvant therapy received neratinib 240 mg/day for 1 year. Early cohorts investigated mandatory prophylaxis with loperamide, then additional budesonide or colestipol. Final cohorts assessed neratinib DE over the first 2 (DE1) or 4 weeks (DE2). The primary endpoint was incidence of grade ≥3 diarrhea. Health-related quality of life (HRQoL) was assessed using FACT-B and EQ-5D-5L. RESULTS: 563 patients were enrolled into six cohorts. All strategies reduced grade ≥3 diarrhea with the lowest incidence in DE1 (DE1 13%; colestipol + loperamide [CL] 21%, DE2 27%; budesonide + loperamide [BL] 28%; loperamide [L] 31%; colestipol + loperamide as needed [CL-PRN] 33%). Diarrhea-related discontinuations occurred early and were lowest in DE1 (DE1 3%; CL 4%; DE2 6%; CL-PRN 8%; BL 11%; L 20%). More patients stayed on neratinib for the prescribed period versus historical controls. Prior pertuzumab use did not affect rates of grade ≥3 diarrhea, diarrhea-related discontinuations, or treatment duration. Early transient reductions in HRQoL scores were observed. CONCLUSIONS: These complete results from CONTROL show improved neratinib tolerability with proactive management at the start of therapy. Two-week neratinib DE with loperamide as needed was particularly effective. GOV REGISTRATION NUMBER: NCT02400476.

Tucatinib vs Placebo, Both in Combination With Trastuzumab and Capecitabine, for Previously Treated ERBB2 (HER2)-Positive Metastatic Breast Cancer in Patients With Brain Metastases: Updated Exploratory Analysis of the HER2CLIMB Randomized Clinical Trial.

Importance: It is estimated that up to 50% of patients with ERBB2 (HER2)-positive metastatic breast cancer (MBC) will develop brain metastases (BMs), which is associated with poor prognosis. Previous reports of the HER2CLIMB trial have demonstrated that tucatinib in combination with trastuzumab and capecitabine provides survival and intracranial benefits for patients with ERBB2-positive MBC and BMs. Objective: To describe overall survival (OS) and intracranial outcomes from tucatinib in combination with trastuzumab and capecitabine in patients with ERBB2-positive MBC and BMs with an additional 15.6 months of follow-up. Design, Setting, and Participants: HER2CLIMB is an international, multicenter, randomized, double-blind, placebo-controlled clinical trial evaluating tucatinib in combination with trastuzumab and capecitabine. The 612 patients, including those with active or stable BMs, had ERBB2-positive MBC previously treated with trastuzumab, pertuzumab, and trastuzumab emtansine. The study was conducted from February 23, 2016, to May 3, 2019. Data from February 23, 2016, to February 8, 2021, were analyzed. Interventions: Patients were randomized 2:1 to receive tucatinib (300 mg orally twice daily) or placebo (orally twice daily), both in combination with trastuzumab (6 mg/kg intravenously or subcutaneously every 3 weeks with an initial loading dose of 8 mg/kg) and capecitabine (1000 mg/m2 orally twice daily on days 1-14 of each 3-week cycle). Main Outcomes and Measures: Evaluations in this exploratory subgroup analysis included OS and intracranial progression-free survival (CNS-PFS) in patients with BMs, confirmed intracranial objective response rate (ORR-IC) and duration of intracranial response (DOR-IC) in patients with measurable intracranial disease at baseline, and new brain lesion-free survival in all patients. Only OS was prespecified before the primary database lock. Results: At baseline, 291 of 612 patients (47.5%) had BMs. Median age was 52 years (range, 22-75 years), and 289 (99.3%) were women. At median follow-up of 29.6 months (range, 0.1-52.9 months), median OS was 9.1 months longer in the tucatinib-combination group (21.6 months; 95% CI, 18.1-28.5) vs the placebo-combination group (12.5 months; 95% CI, 11.2-16.9). The tucatinib-combination group showed greater clinical benefit in CNS-PFS and ORR-IC compared with the placebo-combination group. The DOR-IC was 8.6 months (95% CI, 5.5-10.3 months) in the tucatinib-combination group and 3.0 months (95% CI, 3.0-10.3 months) in the placebo-combination group. Risk of developing new brain lesions as the site of first progression or death was reduced by 45.1% in the tucatinib-combination group vs the placebo-combination group (hazard ratio, 0.55 [95% CI, 0.36-0.85]). Conclusions and Relevance: This subgroup analysis found that tucatinib in combination with trastuzumab and capecitabine improved OS while reducing the risk of developing new brain lesions, further supporting the importance of this treatment option for patients with ERBB2-positive MBC, including those with BMs. Trial Registration: ClinicalTrials.gov Identifier: NCT02614794.

Systemic Therapy for Early- and Late-Stage, Human Epidermal Growth Factor Receptor-2-Positive Breast Cancer.

Systemic therapy for both early-stage and metastatic human epidermal growth factor receptor-2-positive (HER2+) breast cancer has seen significant evolution over the last 20 or more years. Innovative trials leveraging the prognostic and predictive information that neoadjuvant chemotherapy provides has led to preoperative systemic therapy becoming the overwhelmingly favored sequencing in the early-stage setting. However, deintensification of therapy is important to consider for patients with good-risk disease or significant comorbidities. Finally, with the abundance of newly approved agents, drug sequencing in the second-line setting has become an important and individualized decision for patients with metastatic disease.

Trastuzumab deruxtecan versus trastuzumab emtansine in patients with HER2-positive metastatic breast cancer: updated results from DESTINY-Breast03, a randomised, open-label, phase 3 trial.

BACKGROUND: An improvement in progression-free survival was shown with trastuzumab deruxtecan versus trastuzumab emtansine in patients with HER2-positive metastatic breast cancer in the progression-free survival interim analysis of the DESTINY-Breast03 trial. The aim of DESTINY-Breast03 was to compare the efficacy and safety of trastuzumab deruxtecan versus trastuzumab emtansine. METHODS: This open-label, randomised, multicentre, phase 3 trial was done in 169 study centres in North America, Asia, Europe, Australia, and South America. Eligible patients were aged 18 or older, had HER2-positive unresectable or metastatic breast cancer previously treated with trastuzumab and a taxane, had an Eastern Cooperative Oncology Group performance status 0-1, and at least one measurable lesion per Response Evaluation Criteria in Solid Tumours version 1.1. Patients were randomly assigned (1:1) to receive trastuzumab deruxtecan 5·4 mg/kg or trastuzumab emtansine 3·6 mg/kg, both administered by intravenous infusion every 3 weeks. Randomisation was stratified by hormone receptor status, previous treatment with pertuzumab, and history of visceral disease, and was managed through an interactive web-based system. Within each stratum, balanced block randomisation was used with a block size of four. Patients and investigators were not masked to the treatment received. The primary endpoint was progression-free survival by blinded independent central review. The key secondary endpoint was overall survival and this prespecified second overall survival interim analysis reports updated overall survival, efficacy, and safety results. Efficacy analyses were performed using the full analysis set. Safety analyses included all randomly assigned patients who received at least one dose of study treatment. This study is registered with ClinicalTrials.gov, NCT03529110. FINDINGS: Between July 20, 2018, and June 23, 2020, 699 patients were screened for eligibility, 524 of whom were enrolled and randomly assigned to receive trastuzumab deruxtecan (n=261) or trastuzumab emtansine (n=263). Median duration of study follow-up was 28·4 months (IQR 22·1-32·9) with trastuzumab deruxtecan and 26·5 months (14·5-31·3) with trastuzumab emtansine. Median progression-free survival by blinded independent central review was 28·8 months (95% CI 22·4-37·9) with trastuzumab deruxtecan and 6·8 months (5·6-8·2) with trastuzumab emtansine (hazard ratio [HR] 0·33 [95% CI 0·26-0·43]; nominal p<0·0001). Median overall survival was not reached (95% CI 40·5 months-not estimable), with 72 (28%) overall survival events, in the trastuzumab deruxtecan group and was not reached (34·0 months-not estimable), with 97 (37%) overall survival events, in the trastuzumab emtansine group (HR 0·64; 95% CI 0·47-0·87]; p=0·0037). The number of grade 3 or worse treatment-emergent adverse events was similar in patients who received trastuzumab deruxtecan versus trastuzumab emtansine (145 [56%] patients versus 135 [52%] patients). Adjudicated drug-related interstitial lung disease or pneumonitis occurred in 39 (15%) patients treated with trastuzumab deruxtecan and eight (3%) patients treated with trastuzumab emtansine, with no grade 4 or 5 events in either group. INTERPRETATION: Trastuzumab deruxtecan showed a significant improvement in overall survival versus trastuzumab emtansine in patients with HER2-positive metastatic breast cancer, as well as the longest reported median progression-free survival, reaffirming trastuzumab deruxtecan as the standard of care in the second-line setting. A manageable safety profile of trastuzumab deruxtecan was confirmed with longer treatment duration. FUNDING: Daiichi Sankyo and AstraZeneca.