Tumor Biomechanics Alters Metastatic Dissemination of Triple Negative Breast Cancer via Rewiring Fatty Acid Metabolism

In recent decades, the role of tumor biomechanics on cancer cell behavior at the primary site has been increasingly appreciated. However, the effect of primary tumor biomechanics on the latter stages of the metastatic cascade, such as metastatic seeding of secondary sites and outgrowth remains underappreciated. This work sought to address this in the context of triple negative breast cancer (TNBC), a cancer type known to aggressively disseminate at all stages of disease progression. Using mechanically tuneable model systems, mimicking the range of stiffness's typically found within breast tumors, it is found that, contrary to expectations, cancer cells exposed to softer microenvironments are more able to colonize secondary tissues. It is shown that heightened cell survival is driven by enhanced metabolism of fatty acids within TNBC cells exposed to softer microenvironments. It is demonstrated that uncoupling cellular mechanosensing through integrin β1 blocking antibody effectively causes stiff primed TNBC cells to behave like their soft counterparts, both in vitro and in vivo. This work is the first to show that softer tumor microenvironments may be contributing to changes in disease outcome by imprinting on TNBC cells a greater metabolic flexibility and conferring discrete cell survival advantages.

Giredestrant for Estrogen Receptor-Positive, HER2-Negative, Previously Treated Advanced Breast Cancer: Results From the Randomized, Phase II acelERA Breast Cancer Study

PURPOSE

To compare giredestrant and physician's choice of endocrine monotherapy (PCET) for estrogen receptor-positive, HER2-negative, advanced breast cancer (BC) in the phase II acelERA BC study (ClinicalTrials.gov identifier: NCT04576455).

METHODS

Post-/pre-/perimenopausal women, or men, age 18 years or older with measurable disease/evaluable bone lesions, whose disease progressed after 1-2 lines of systemic therapy (≤1 targeted, ≤1 chemotherapy regimen, prior fulvestrant allowed) were randomly assigned 1:1 to giredestrant (30 mg oral once daily) or fulvestrant/aromatase inhibitor per local guidelines (+luteinizing hormone-releasing hormone agonist in pre-/perimenopausal women, and men) until disease progression/unacceptable toxicity. Stratification was by visceral versus nonvisceral disease, prior cyclin-dependent kinase 4/6 inhibitor, and prior fulvestrant. The primary end point was investigator-assessed progression-free survival (INV-PFS).

RESULTS

At clinical cutoff (February 18, 2022; median follow-up: 7.9 months; N = 303), the INV-PFS hazard ratio (HR) was 0.81 (95% CI, 0.60 to 1.10; P = .1757). In the prespecified secondary end point analysis of INV-PFS by ESR1 mutation (m) status in circulating tumor DNA-evaluable patients (n = 232), the HR in patients with a detectable ESR1m (n = 90) was 0.60 (95% CI, 0.35 to 1.03) versus 0.88 (95% CI, 0.54 to 1.42) in patients with no ESR1m detected (n = 142). Related grade 3-4 adverse events (AEs), serious AEs, and discontinuations due to AEs were balanced across arms.

CONCLUSION

Although the acelERA BC study did not reach statistical significance for its primary INV-PFS end point, there was a consistent treatment effect with giredestrant across most key subgroups and a trend toward favorable benefit among patients with ESR1-mutated tumors. Giredestrant was well tolerated, with a safety profile comparable to PCET and consistent with known endocrine therapy risks. Overall, these data support the continued investigation of giredestrant in other studies.

COVID-19 Stroke Apical Lung Examination Study 2: a national prospective CTA biomarker study of the lung apices, in patients presenting with suspected acute stroke (COVID SALES 2)

BACKGROUND

Apical ground-glass opacification (GGO) identified on CT angiography (CTA) performed for suspected acute stroke was developed in 2020 as a coronavirus-disease-2019 (COVID-19) diagnostic and prognostic biomarker in a retrospective study during the first wave of COVID-19.

OBJECTIVE

To prospectively validate whether GGO on CTA performed for suspected acute stroke is a reliable COVID-19 diagnostic and prognostic biomarker and whether it is reliable for COVID-19 vaccinated patients.

METHODS

In this prospective, pragmatic, national, multi-center validation study performed at 13 sites, we captured study data consecutively in patients undergoing CTA for suspected acute stroke from January-March 2021. Demographic and clinical features associated with stroke and COVID-19 were incorporated. The primary outcome was the likelihood of reverse-transcriptase-polymerase-chain-reaction swab-test-confirmed COVID-19 using the GGO biomarker. Secondary outcomes investigated were functional status at discharge and survival analyses at 30 and 90 days. Univariate and multivariable statistical analyses were employed.

RESULTS

CTAs from 1,111 patients were analyzed, with apical GGO identified in 8.5 % during a period of high COVID-19 prevalence. GGO showed good inter-rater reliability (Fleiss κ = 0.77); and high COVID-19 specificity (93.7 %, 91.8-95.2) and negative predictive value (NPV; 97.8 %, 96.5-98.6). In subgroup analysis of vaccinated patients, GGO remained a good diagnostic biomarker (specificity 93.1 %, 89.8-95.5; NPV 99.7 %, 98.3-100.0). Patients with COVID-19 were more likely to have higher stroke score (NIHSS (mean +/- SD) 6.9 +/- 6.9, COVID-19 negative, 9.7 +/- 9.0, COVID-19 positive; p = 0.01), carotid occlusions (6.2 % negative, 14.9 % positive; p = 0.02), and larger infarcts on presentation CT (ASPECTS 9.4 +/- 1.5, COVID-19 negative, 8.6 +/- 2.4, COVID-19 positive; p = 0.00). After multivariable logistic regression, GGO (odds ratio 15.7, 6.2-40.1), myalgia (8.9, 2.1-38.2) and higher core body temperature (1.9, 1.1-3.2) were independent COVID-19 predictors. GGO was associated with worse functional outcome on discharge and worse survival after univariate analysis. However, after adjustment for factors including stroke severity, GGO was not independently predictive of functional outcome or mortality.

CONCLUSION

Apical GGO on CTA performed for patients with suspected acute stroke is a reliable diagnostic biomarker for COVID-19, which in combination with clinical features may be useful in COVID-19 triage.

Characterisation and reproducibility of the HumanMethylationEPIC v2.0 BeadChip for DNA methylation profiling

BACKGROUND

The Illumina family of Infinium Methylation BeadChip microarrays has been widely used over the last 15 years for genome-wide DNA methylation profiling, including large-scale and population-based studies, due to their ease of use and cost effectiveness. Succeeding the popular HumanMethylationEPIC BeadChip (EPICv1), the recently released Infinium MethylationEPIC v2.0 BeadChip (EPICv2) claims to extend genomic coverage to more than 935,000 CpG sites. Here, we comprehensively characterise the reproducibility, reliability and annotation of the EPICv2 array, based on bioinformatic analysis of both manifest data and new EPICv2 data from diverse biological samples.

RESULTS

We find a high degree of reproducibility with EPICv1, evidenced by comparable sensitivity and precision from empirical cross-platform comparison incorporating whole genome bisulphite sequencing (WGBS), and high correlation between technical sample replicates, including between samples with DNA input levels below the manufacturer's recommendation. We provide a full assessment of probe content, evaluating genomic distribution and changes from previous array versions. We characterise EPICv2's new feature of replicated probes and provide recommendations as to the superior probes. In silico analysis of probe sequences demonstrates that probe cross-hybridisation remains a significant problem in EPICv2. By mapping the off-target sites at single nucleotide resolution and comparing with WGBS we show empirical evidence for preferential off-target binding.

CONCLUSIONS

Overall, we find EPICv2 a worthy successor to the previous Infinium methylation microarrays, however some technical issues remain. To support optimal EPICv2 data analysis we provide an expanded version of the EPICv2 manifest to aid researchers in understanding probe design, data processing, choosing appropriate probes for analysis and for integration with methylation datasets from previous versions of the Infinium Methylation BeadChip.

The potential of epigenetic therapy to target the 3D epigenome in endocrine-resistant breast cancer

Three-dimensional (3D) epigenome remodeling is an important mechanism of gene deregulation in cancer. However, its potential as a target to counteract therapy resistance remains largely unaddressed. Here, we show that epigenetic therapy with decitabine (5-Aza-mC) suppresses tumor growth in xenograft models of pre-clinical metastatic estrogen receptor positive (ER+) breast tumor. Decitabine-induced genome-wide DNA hypomethylation results in large-scale 3D epigenome deregulation, including de-compaction of higher-order chromatin structure and loss of boundary insulation of topologically associated domains. Significant DNA hypomethylation associates with ectopic activation of ER-enhancers, gain in ER binding, creation of new 3D enhancer-promoter interactions and concordant up-regulation of ER-mediated transcription pathways. Importantly, long-term withdrawal of epigenetic therapy partially restores methylation at ER-enhancer elements, resulting in a loss of ectopic 3D enhancer-promoter interactions and associated gene repression. Our study illustrates the potential of epigenetic therapy to target ER+ endocrine-resistant breast cancer by DNA methylation-dependent rewiring of 3D chromatin interactions, which are associated with the suppression of tumor growth.

Activity and safety of enobosarm, a novel, oral, selective androgen receptor modulator, in androgen receptor-positive, oestrogen receptor-positive, and HER2-negative advanced breast cancer (Study G200802): a randomised, open-label, multicentre, multinational, parallel design, phase 2 trial

BACKGROUND

The androgen receptor is a tumour suppressor in oestrogen receptor-positive breast cancer. The activity and safety of enobosarm, an oral selective androgen receptor modulator, was evaluated in women with oestrogen receptor (ER)-positive, HER2-negative, and androgen receptor (AR)-positive disease.

METHODS

Women who were postmenopausal (aged ≥18 years) with previously treated ER-positive, HER2-negative, locally advanced or metastatic breast cancer with an Eastern Cooperative Oncology Group performance status of 0-2 were enrolled in a randomised, open-label, multicentre, multinational, parallel design, phase 2 trial done at 35 cancer treatment centres in nine countries. Participants were stratified on the setting of immediately preceding endocrine therapy and the presence of bone-only metastasis and randomly assigned (1:1) to 9 mg or 18 mg oral enobosarm daily using an interactive web response system. The primary endpoint was clinical benefit rate at 24 weeks in those with centrally confirmed AR-positive disease (ie, the evaluable population). This trial is registered with ClinicalTrials.gov (NCT02463032).

FINDINGS

Between Sept 10, 2015, and Nov 28, 2017, 136 (79%) of 172 patients deemed eligible were randomly assigned to 9 mg (n=72) or 18 mg (n=64) oral enobosarm daily. Of these 136 patients, 102 (75%) patients formed the evaluable population (9 mg, n=50; 18 mg, n=52). The median age was 60·5 years (IQR 52·3-69·3) in the 9 mg group and 62·5 years (54·0-69·3) in the 18 mg group. The median follow-up was 7·5 months (IQR 2·9-14·1). At 24 weeks, 16 (32%, 95% CI 20-47) of 50 in the 9 mg group and 15 (29%, 17-43) of 52 in the 18 mg group had clinical benefit. Six (8%) of 75 patients who received 9 mg and ten (16%) of 61 patients who received 18 mg had grade 3 or grade 4 drug-related adverse events, most frequently increased hepatic transaminases (three [4%] of 75 in the 9 mg group and two [3%] of 61 in the 18 mg group), hypercalcaemia (two [3%] and two [3%]), and fatigue (one [1%] and two [3%]). Four deaths (one in the 9 mg group and three in the 18 mg group) were deemed unrelated to the study drug.

INTERPRETATION

Enobosarm has anti-tumour activity in patients with ER-positive, HER2-negative advanced breast cancer, showing that AR activation can result in clinical benefit, supporting further clinical investigation of selective AR activation strategies for the treatment of AR-positive, ER-positive, HER2-negative advanced breast cancer.

FUNDING

GTx.

Selective CDK7 inhibition suppresses cell cycle progression and MYC signaling while enhancing apoptosis in therapy-resistant estrogen receptor positive breast cancer

PURPOSE

Resistance to endocrine therapy (ET) and CDK4/6 inhibitors (CDK4/6i) is a clinical challenge in estrogen receptor (ER) positive (ER+) breast cancer (BC). Cyclin-dependent kinase 7 (CDK7) is a candidate target in endocrine resistant ER+ BC models and selective CDK7 inhibitors (CDK7i) are in clinical development for the treatment of ER+ BC. Nonetheless, the precise mechanisms responsible for the activity of CDK7i in ER+ BC remain elusive. Herein, we sought to unravel these mechanisms.

EXPERIMENTAL DESIGN

We conducted multi-omic analyses in ER+ BC models in vitro and in vivo including models with different genetic backgrounds. We also performed genome wide CRISPR knock-out library screens to identify potential therapeutic vulnerabilities in CDK4/6i resistance models.

RESULTS

We found that the on-target anti-tumor effects of CDK7 inhibition in ER+ BC are in part p53 dependent, involve cell-cycle inhibition and suppression of c-MYC. Moreover, CDK7 inhibition exhibited cytotoxic effects, distinctive from the cytostatic nature of ETs and CDK4/6i. CDK7 inhibition resulted in suppression of ER phosphorylation at S118, however, long-term CDK7 inhibition resulted in increased ER signaling, supporting the combination of ET with a CDK7i. Lastly, genome wide CRISPR/Cas9 screens identified CDK7 and MYC signaling as putative vulnerabilities in CDK4/6i resistance, and CDK7 inhibition effectively inhibited CDK4/6i resistant models.

CONCLUSIONS

Taken together, these findings support the clinical investigation of selective CDK7 inhibition combined with ET to overcome treatment resistance in ER+ BC. In addition, our study highlights the potential of increased MYC activity and intact P53 as predictors for sensitivity to CDK7 inhibitor-based treatments.

Phase Ia/b Study of Giredestrant ± Palbociclib and ± Luteinizing Hormone-Releasing Hormone Agonists in Estrogen Receptor-Positive, HER2-Negative, Locally Advanced/Metastatic Breast Cancer

PURPOSE

Giredestrant is an investigational next-generation, oral, selective estrogen receptor antagonist and degrader for the treatment of estrogen receptor-positive (ER+) breast cancer. We present the primary analysis results of the phase Ia/b GO39932 study (NCT03332797).

PATIENTS AND METHODS

Patients with ER+, HER2-negative locally advanced/metastatic breast cancer previously treated with endocrine therapy received single-agent giredestrant (10, 30, 90, or 250 mg), or giredestrant (100 mg) ± palbociclib 125 mg ± luteinizing hormone-releasing hormone (LHRH) agonist. Detailed cardiovascular assessment was conducted with giredestrant 100 mg. Endpoints included safety (primary), pharmacokinetics, pharmacodynamics, and efficacy.

RESULTS

As of January 28, 2021, with 175 patients enrolled, no dose-limiting toxicity was observed, and the MTD was not reached. Adverse events (AE) related to giredestrant occurred in 64.9% and 59.4% of patients in the single-agent ± LHRH agonist and giredestrant + palbociclib ± LHRH agonist cohorts, respectively (giredestrant-only-related grade 3/4 AEs were reported in 4.5% of patients across the single-agent cohorts and 3.1% of those with giredestrant + palbociclib). Dose-dependent asymptomatic bradycardia was observed, but no clinically significant changes in cardiac-related outcomes: heart rate, blood pressure, or exercise duration. Clinical benefit was observed in all cohorts (48.6% of patients in the single-agent cohort and 81.3% in the giredestrant + palbociclib ± LHRH agonist cohort), with no clear dose relationship, including in patients with ESR1-mutated tumors.

CONCLUSIONS

Giredestrant was well tolerated and clinically active in patients who progressed on prior endocrine therapy. Results warrant further evaluation of giredestrant in randomized trials in early- and late-stage ER+ breast cancer.

The androgen receptor interacts with GATA3 to transcriptionally regulate a luminal epithelial cell phenotype in breast cancer

BACKGROUND

The androgen receptor (AR) is a tumor suppressor in estrogen receptor (ER) positive breast cancer, a role sustained in some ER negative breast cancers. Key factors dictating AR genomic activity in a breast context are largely unknown. Herein, we employ an unbiased chromatin immunoprecipitation-based proteomic technique to identify endogenous AR interacting co-regulatory proteins in ER positive and negative models of breast cancer to gain new insight into mechanisms of AR signaling in this disease.

RESULTS

The DNA-binding factor GATA3 is identified and validated as a novel AR interacting protein in breast cancer cells irrespective of ER status. AR activation by the natural ligand 5α-dihydrotestosterone (DHT) increases nuclear AR-GATA3 interactions, resulting in AR-dependent enrichment of GATA3 chromatin binding at a sub-set of genomic loci. Silencing GATA3 reduces but does not prevent AR DNA binding and transactivation of genes associated with AR/GATA3 co-occupied loci, indicating a co-regulatory role for GATA3 in AR signaling. DHT-induced AR/GATA3 binding coincides with upregulation of luminal differentiation genes, including EHF and KDM4B, established master regulators of a breast epithelial cell lineage. These findings are validated in a patient-derived xenograft model of breast cancer. Interaction between AR and GATA3 is also associated with AR-mediated growth inhibition in ER positive and ER negative breast cancer.

CONCLUSIONS

AR and GATA3 interact to transcriptionally regulate luminal epithelial cell differentiation in breast cancer regardless of ER status. This interaction facilitates the tumor suppressor function of AR and mechanistically explains why AR expression is associated with less proliferative, more differentiated breast tumors and better overall survival in breast cancer.

Interleukin-3 production by basal-like breast cancer cells is associated with poor prognosis

Breast cancer represents a collection of pathologies with different molecular subtypes, histopathology, risk factors, clinical behavior, and responses to treatment. "Basal-like" breast cancers predominantly lack the receptors for estrogen and progesterone (ER/PR), lack amplification of human epidermal growth factor receptor 2 (HER2) but account for 10-15% of all breast cancers, are largely insensitive to targeted treatment and represent a disproportionate number of metastatic cases and deaths. Analysis of interleukin (IL)-3 and the IL-3 receptor subunits (IL-3RA + CSF2RB) reveals elevated expression in predominantly the basal-like group. Further analysis suggests that IL-3 itself, but not the IL-3 receptor subunits, associates with poor patient outcome. Histology on patient-derived xenografts supports the notion that breast cancer cells are a significant source of IL-3 that may promote disease progression. Taken together, these observations suggest that IL-3 may be a useful marker in solid tumors, particularly triple negative breast cancer, and warrants further investigation into its contribution to disease pathogenesis.

Clinical Guidance on the Monitoring and Management of Trastuzumab Deruxtecan (T-DXd)-Related Adverse Events: Insights from an Asia-Pacific Multidisciplinary Panel

Trastuzumab deruxtecan (T-DXd)-an antibody-drug conjugate targeting the human epidermal growth factor receptor 2 (HER2)-improved outcomes of patients with HER2-positive and HER2-low metastatic breast cancer. Guidance on monitoring and managing T-DXd-related adverse events (AEs) is an emerging unmet need as translating clinical trial experience into real-world practice may be difficult due to practical and cultural considerations and differences in health care infrastructure. Thus, 13 experts including oncologists, pulmonologists and a radiologist from the Asia-Pacific region gathered to provide recommendations for T-DXd-related AE monitoring and management by using the latest evidence from the DESTINY-Breast trials, our own clinical trial experience and loco-regional health care considerations. While subgroup analysis of Asian (excluding Japanese) versus overall population in the DESTINY-Breast03 uncovered no major differences in the AE profile, we concluded that proactive monitoring and management are essential in maximising the benefits with T-DXd. As interstitial lung disease (ILD)/pneumonitis is a serious AE, patients should undergo regular computed tomography scans, but the frequency may have to account for the median time of ILD/pneumonitis onset and access. Trastuzumab deruxtecan appears to be a highly emetic regimen, and prophylaxis with serotonin receptor antagonists and dexamethasone (with or without neurokinin-1 receptor antagonist) should be considered. Health care professionals should be vigilant for treatable causes of fatigue, and patients should be encouraged to use support groups and practice low-intensity exercises. To increase treatment acceptance, patients should be made aware of alopecia risk prior to starting T-DXd. Detailed monitoring and management recommendations for T-DXd-related AEs are discussed further.

Antibody-Drug Conjugates: Ushering in a New Era of Cancer Therapy

Antibody-drug conjugates (ADCs) have provided new therapeutic options and significant promise for patients with cancer, particularly where existing treatments are limited. Substantial effort in ADC development is underway globally, with 13 ADCs currently approved and many more in development. The therapeutic benefits of ADCs leverage the ability to selectively target cancer cells through antibody binding, resultant relative sparing of non-malignant tissues, and the targeted delivery of a cytotoxic payload. Consequently, this drug class has demonstrated activity in multiple malignancies refractory to standard therapeutic options. Despite this, limitations exist, including narrow therapeutic windows, unique toxicity profiles, development of therapeutic resistance, and appropriate biomarker selection. This review will describe the development of ADCs, their mechanisms of action, pivotal trials, and approved indications and identify common themes. Current challenges and opportunities will be discussed for this drug class in cancer therapeutics at a time when significant developments in antibody therapies, immunotherapy, and targeted agents are occurring.

Trastuzumab deruxtecan versus treatment of physician's choice in patients with HER2-positive metastatic breast cancer (DESTINY-Breast02): a randomised, open-label, multicentre, phase 3 trial

BACKGROUND

In the single-arm, phase 2 DESTINY-Breast01 trial, trastuzumab deruxtecan showed robust activity in patients with HER2-positive metastatic breast cancer who were refractory or resistant to trastuzumab emtansine; a population with scarce effective treatments. In DESTINY-Breast02, we aimed to compare the efficacy and safety of trastuzumab deruxtecan with treatment of physician's choice in this patient population.

METHODS

This randomised, open-label, multicentre, phase 3 trial was conducted at 227 sites (hospitals, university hospitals, clinics, community centres, and private oncology centres) in North America, Europe, Asia, Australia, Brazil, Israel, and Türkiye. Eligible patients were aged 18 years or older, had unresectable or HER2-positive metastatic breast cancer, previously received trastuzumab emtansine, disease progression, an Eastern Cooperative Oncology Group performance status of 0 or 1, and adequate renal and hepatic function. Patients were randomly assigned (2:1) to receive trastuzumab deruxtecan (intravenously at 5·4 mg/kg once every 3 weeks) or treatment of physician's choice using block randomisation. Treatment of physician's choice was either capecitabine (1250 mg/m2; orally twice per day on days 1-14) plus trastuzumab (8 mg/kg intravenously on day 1 then 6 mg/kg once per day) or capecitabine (1000 mg/m2) plus lapatinib (1250 mg orally once per day on days 1-21), with a 21-day schedule. The primary endpoint was progression-free survival based on blinded independent central review in the full analysis set. This study is registered with ClinicalTrials.gov, NCT03523585.

FINDINGS

Between Sept 6, 2018, and Dec 31, 2020, 608 patients were randomly assigned to receive trastuzumab deruxtecan (n=406; two did not receive treatment) or treatment of physician's choice (n=202; seven did not receive treatment). 608 (100%) patients were included in the full analysis set. The median age was 54·2 years (IQR 45·5-63·4) in the trastuzumab deruxtecan group and 54·7 years (48·0-63·0) in the treatment of physician's choice group. 384 (63%) patients were White, 603 (99%) were female, and five (<1%) were male. The median follow-up was 21·5 months (IQR 15·2-28·4) in the trastuzumab deruxtecan group and 18·6 months (8·8-26·0) in the treatment of physician's choice group. Median progression-free survival by blinded independent central review was 17·8 months (95% CI 14·3-20·8) in the trastuzumab deruxtecan group versus 6·9 months (5·5-8·4) in the treatment of physician's choice group (HR 0·36 [0·28-0·45]; p<0·0001). The most common treatment-emergent adverse events were nausea (293 [73%] of 404 with trastuzumab deruxtecan vs 73 [37%] of 195 with treatment of physician's choice), vomiting (152 [38%] vs 25 [13%]), alopecia (150 [37%] vs eight [4%]), fatigue (147 [36%] vs 52 [27%]), diarrhoea (109 [27%] vs 105 [54%]), and palmar-plantar erythrodysaesthesia (seven [2%] vs 100 [51%]). Grade 3 or higher treatment-emergent adverse events occurred in 213 (53%) patients receiving trastuzumab deruxtecan versus 86 (44%) receiving treatment of physician's choice; whereas drug-related interstitial lung disease occurred in 42 (10%; including two grade 5 death events) versus one (<1%).

INTERPRETATION

DESTINY-Breast02 shows the favourable benefit-risk profile of trastuzumab deruxtecan in patients with HER2 positive metastatic breast cancer, as previously reported in DESTINY-Breast01, and is the first randomised study to show that one antibody-drug conjugate can overcome resistance to a previous one.

FUNDING

Daiichi Sankyo and AstraZeneca.

Monitoring AKT activity and targeting in live tissue and disease contexts using a real-time Akt-FRET biosensor mouse

Aberrant AKT activation occurs in a number of cancers, metabolic syndrome, and immune disorders, making it an important target for the treatment of many diseases. To monitor spatial and temporal AKT activity in a live setting, we generated an Akt-FRET biosensor mouse that allows longitudinal assessment of AKT activity using intravital imaging in conjunction with image stabilization and optical window technology. We demonstrate the sensitivity of the Akt-FRET biosensor mouse using various cancer models and verify its suitability to monitor response to drug targeting in spheroid and organotypic models. We also show that the dynamics of AKT activation can be monitored in real time in diverse tissues, including in individual islets of the pancreas, in the brown and white adipose tissue, and in the skeletal muscle. Thus, the Akt-FRET biosensor mouse provides an important tool to study AKT dynamics in live tissue contexts and has broad preclinical applications.

CDK4/6 inhibitor resistance in estrogen receptor positive breast cancer, a 2023 perspective

CDK4/6 inhibitors have become game-changers in the treatment of estrogen receptor-positive (ER+) breast cancer, and in combination with endocrine therapy are the standard of care first-line treatment for ER+/HER2-negative advanced breast cancer. Although CDK4/6 inhibitors prolong survival for these patients, resistance is inevitable and there is currently no clear standard next-line treatment. There is an urgent unmet need to dissect the mechanisms which drive intrinsic and acquired resistance to CDK4/6 inhibitors and endocrine therapy to guide the subsequent therapeutic decisions. We will review the insights gained from preclinical studies and clinical cohorts into the diverse mechanisms of CDK4/6 inhibitor action and resistance, and highlight potential therapeutic strategies in the context of CDK4/6 inhibitor resistance.

Abstract PD13-12: PD13-12 Imlunestrant, an oral selective estrogen receptor degrader, in combination with abemaciclib with or without an aromatase inhibitor, in estrogen receptor-positive advanced breast cancer: Results from the phase 1a/b EMBER study

Background: Imlunestrant is a novel, orally bioavailable selective estrogen receptor degrader (SERD) with pure antagonistic properties that result in sustained inhibition of estrogen receptor (ER)-dependent gene transcription and cell growth. Preclinically, imlunestrant has favorable efficacy and pharmacokinetic (PK) properties, including antitumor activity in ESR1-mutant models, along with enhanced efficacy when combined with abemaciclib. In dose escalation (Phase 1a) and dose expansion (Phase 1b) in the EMBER study, imlunestrant monotherapy was well tolerated with favorable safety, PK and encouraging antitumor activity in heavily pre-treated ER+, HER2- advanced breast cancer (aBC) patients (Jhaveri, ASCO 2022); imlunestrant recommended phase 2 dose (RP2D) was determined as 400mg QD. Here, we present the phase 1b dose expansion of imlunestrant with abemaciclib ± aromatase inhibitor (AI) in EMBER (NCT04188548).

Methods: Phase 1b enrolled patients with ER-positive (ER+), HER2-negative (HER2-) aBC [shown prior endocrine therapy (ET) sensitivity or untreated de novo aBC; ≤1 prior therapies for aBC but must not have received a prior CDK4/6 inhibitor]. Patients were randomized, based on menopausal status and presence of visceral metastases, to receive imlunestrant + abemaciclib OR imlunestrant + abemaciclib + AI. Men and premenopausal women received a concomitant GnRH agonist. Serial plasma samples were obtained for PK and ctDNA analysis. Key endpoints included safety and tolerability, PK, objective response rate (ORR) per RECIST v1.1 (ORR: complete response [CR] or partial response [PR]) in patients with measurable disease), and clinical benefit rate (CBR: CR or PR, or stable disease ≥24 weeks) in patients enrolled ≥24 weeks prior to data cut.

Results: As of 26 May 2022, 85 patients have received imlunestrant [n=80 at 400 mg (RP2D); n=5 at 800 mg] in combination with abemaciclib (150mg twice daily) ± AI. Forty-eight (56%) patients had visceral disease and 9% had at least 1 ESR1 mutation detected in ctDNA at baseline. Patients were predominantly (75%) ET pre-treated, 51% with an AI; and 8% and 5%, respectively, had received prior chemotherapy or fulvestrant, for aBC. The most common treatment-emergent adverse events were diarrhea (87%), nausea (58%), fatigue (45%), neutropenia (39%) and abdominal pain (34%). The majority of treatment-related AEs (TRAEs) were Grade 1 or 2, with Grade ≥3 TRAEs occurring in 36% of patients. Most common TRAEs at RP2D (400mg) were diarrhea (81%), nausea (45%), fatigue (33%) and neutropenia (35%). No patient discontinued treatment due to an AE. Dose reductions were required of both imlunestrant and abemaciclib in 6 (7%) patients and of either imlunestrant in 3 (4%) or abemaciclib in 22 (26%) patients. Preliminary efficacy is presented in Table 1.

Conclusion: Imlunestrant in combination with abemaciclib ± AI showed acceptable safety and tolerability, comparable to the MONARCH 2 trial of fulvestrant + abemaciclib, along with evidence of clinical activity in ER+, HER2- aBC patients. These data suggest no additive toxicity of imlunestrant when administered in combination with abemaciclib, along with comparable clinical benefit to that observed in MONARCH 2. Further data will be presented at the meeting. The phase 3, EMBER-3 study is ongoing; evaluating imlunestrant, investigator’s choice ET, and imlunestrant + abemaciclib in ET pre-treated ER+, HER2- aBC patients (NCT04975308).

Table 1. Preliminary efficacy in combination therapies in EMBER

Citation Format: Komal Jhaveri, Hwei-Chung Wang, Cynthia Ma, Elgene Lim, Jessica J. Tao, Luis Manso, Jean-Yves Pierga, Ritesh Parajuli, Yolanda Jerez Gilarranz, Yen-Shen Lu, Muralidhar Beeram, Tim Larson, Ajay Dhakal, Roohi Ismail-Khan, Claudia Karacsonyi, Shanshan Cao, Cynthia Osborne, Shawn T. Estrem, Bastien Nguyen, Yujia Li, Eunice Yuen. PD13-12 Imlunestrant, an oral selective estrogen receptor degrader, in combination with abemaciclib with or without an aromatase inhibitor, in estrogen receptor-positive advanced breast cancer: Results from the phase 1a/b EMBER study [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD13-12.

Abstract PD9-01: Stromal mediators of lymphocyte exclusion and dysfunction in triple negative breast cancer

Triple negative breast cancer (TNBC) is the most aggressive breast cancer subtype with poor prognosis and limited treatment options. One of the mechanisms contributing to this is the ability of TNBC tumors to evade anti-tumour response, limiting the success of immune-checkpoint therapy. In recent studies of the tumor microenvironment, stromal cells have emerged as potential important mediators of lymphocyte function in TNBC. Multi-omics studies from our group and others have elucidated the heterogeneity of stromal cells and their interactions with immune cells in TNBC. However, the clinical relevance and functional characteristics of these relationships remain poorly explored. Our previous work revealed functionally distinct subpopulations of stromal cells in breast cancer: endothelial cells, myofibroblast-like cancer-associated fibroblasts (myCAFs), inflammatory-CAFs (iCAFs), and perivascular-like cells which resemble pericyte and smooth muscle cells in immature and differentiated states (imPVLs; dPVLs), respectively. Here we directly explored the clinical relevance of these stromal subpopulations and their association with immune evasion in a large independent TNBC cohort with long-term survival data. Using markers derived from our single-cell multi-omics studies, we performed multiplex immunofluorescence using the OPAL9 platform on tumor microarrays from 222 TNBC patients to mark myCAFs, iCAFs, dPVLs, endothelial cells, CD8 and/or PD1 positive T-cells. Digital imaging analysis (QuPath) revealed a significant negative correlation between the abundance of stromal cells and CD8 T cells. This cytotoxic T-cell exclusion is primarily driven by smooth muscle dPVLs. Parallel to this T-cell exclusion, our functional studies demonstrate that stromal cells suppress T-cell proliferation. Using multiple ex vivo co-culture models of primary TNBC CAFs and peripheral blood mononuclear cells (PBMCs) from healthy and matched donors, we show that CAFs suppress the proliferative capability of CD4 and CD8 T-cells. ScRNA-seq of these co-culture models demonstrate that CAF educated T cells are driven into a LAG3+ exhausted state enriched for canonical pathways of immunosuppressive cytokine signaling. Our findings suggest that manipulation of these stromal subpopulations could elicit a more effective immune response in a subset of patients through inhibiting T-cell dysfunction and exclusion.

Citation Format: Julia Chen, Sunny Wu, Travis Ruan, Iveta Slapetova, Ewan Millar, Elgene Lim, Alex Swarbrick. Stromal mediators of lymphocyte exclusion and dysfunction in triple negative breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD9-01.

Abstract P4-08-16: Selective Androgen Receptor Modulators in combination with CDK4/6 inhibitors demonstrate anti-cancer activity in preclinical treatment resistant ER+AR+ breast cancer models

Background: The Androgen Receptor (AR) is expressed in up to 90% of all ER+ breast cancers and has been associated with better patient outcome. While androgens were used at a high dose as an anticancer therapy historically, this was discontinued with the advent of Tamoxifen due to virilising effects. Non-steroidal, tissue selective AR modulators (SARMs) represent an attractive alternative, offering a targeted approach to AR activation. Recent compelling pre-clinical data has established that the AR is a tumour suppressor in ER+ breast cancers and that AR activation with a natural androgen or a SARM suppressed ER-driven tumour growth, in preclinical models of endocrine-sensitive and -resistant ER+ breast cancer. Here, we evaluate the efficacy of a SARM (enobosarm) and a natural AR ligand (dihydrotestosterone, DHT) in the context of metastatic, CDK4/6 inhibitor (CDK4/6i) resistant breast cancer. Methods: Enobosarm and palbociclib treatments were evaluated in vitro by colony forming assays using CDK4/6i resistant (MCF7 PalbR) and both endocrine and CDK4/6i resistant (MCF7 cTamPalbR) cell lines. Next, enobosarm or DHT and palbociclib treatment were evaluated in vivo using endocrine and CDK4/6i resistant ER+ patient derived xenograft models (PDX) and cell line xenograft models. IHC, RNA and ChIP sequencing (AR, ER, H3K27ac) were subsequently performed on the harvested tumours. Results: While in vitro and in vivo growth of CDK4/6i resistant preclinical models was inhibited by treatment with a SARM or DHT alone, growth inhibition was more potent and durable in combination with a CDK4/6i. Gene set enrichment analysis of RNA-seq data integrated with ChIP-seq data revealed upregulation of an AR gene signature associated with a better prognosis following treatment with SARM. Co-treatment with a SARM and a CDK4/6i also enhanced AR signalling compared to SARM alone indicating an interaction of the two signalling pathways. Conclusion: Our data indicates that combination treatment with an AR agonist and a CDK4/6i represents a novel therapeutic strategy for CDK4/6i resistant ER+AR+ breast cancers

Citation Format: Allegra Freelander, Geraldine laven-Law, Leila Eshraghi, Nimmy Geetha, Peta Somerville, Marie Pickering, Sarah Alexandrou, C. Elizabeth Caldon, Wayne D. Tilley, Theresa E. Hickey, Elgene Lim. Selective Androgen Receptor Modulators in combination with CDK4/6 inhibitors demonstrate anti-cancer activity in preclinical treatment resistant ER+AR+ breast cancer models. [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-08-16.

Abstract OT2-01-10: WinPro: A window of opportunity study of endocrine therapy with and without prometrium in postmenopausal women with early-stage hormone receptor-positive breast cancer

WinPro: A window of opportunity study of endocrine therapy with and without prometrium in postmenopausal women with early-stage hormone receptor-positive breast cancer Authors Teesha Downton1,2,3, Davendra Segara3, Andrew Ong4, Janne Bingham5, Emma-Kate Carson4, Julia Chen1,2,3, Kate Middleton3, Geoffrey Lindeman6, Andrew Parker3, Elgene Lim1,2,3. Affiliations 1Garvan Institute of Medical Research, Darlinghurst NSW, Australia; 2School of Clinical Medicine, St Vincent’s Healthcare Clinical Campus, Faculty of Medicine and Health, University of New South Wales Sydney, Australia; 3St Vincent’s Hospital Sydney, Darlinghurst NSW, Australia; 4Campbelltown Hospital, Campbelltown NSW, Australia; 5Royal Adelaide Hospital, Adelaide SA, Australia; 6Walter & Eliza Hall Institute of Medical Research, Parkville VIC, Australia Disclosures T. Downton: None. D. Segara: None. A. Ong: None. J. Bingham: None. E. Carson: None. J. Chen: None. K. Middleton: None. G. Lindeman: None. A. Parker: None. E. Lim: Advisory Board for Pfizer, Astra Zeneca, Lilly, Roche, Novartis, Gilead Australia. Research Funding from Pfizer, Novartis, Bayer. Abstract Background: Preclinical studies have observed that progesterone has inhibitory effects on the estrogen-stimulated growth of estrogen receptor (ER)-positive, progesterone receptor (PR)-positive breast cancer. Mohammed H et al. (Nature 2015) identified that activated PR associates with the ER and modulates the interactions of the ER with chromatin, with a shift towards the transcription of genes associated with apoptosis and differentiation, and away from genes associated with proliferation. We hypothesize that the addition of prometrium, a microionized progesterone, may enhance the anti-proliferative effects of standard endocrine therapy in women with ER-positive PR-positive breast cancer. Trial Design: WinPro (NCT03906669) is an ongoing multicenter, phase II, randomized, open-label, window of opportunity study comparing the effect on standard endocrine therapy with or without prometrium on breast cancer cell proliferation. The study population is postmenopausal women with early-stage operable breast cancer where the tumor is ≥5mm on imaging, ER ≥10%, PR≥10%, and HER2-negative. Patients currently on hormone replacement therapy or the oral contraceptive pill, or who have a history of endometrial cancer or venous thromboembolism are not eligible. Patients are randomized 1:1:1 to letrozole 2.5mg daily, letrozole 2.5mg + prometrium 300mg daily, or tamoxifen 20mg + prometrium 300mg daily. Allocated treatment is taken for 14 days prior to surgery. Primary surgery and adjuvant treatment is as per standard of care. Objectives: The primary objective is to compare the geometric mean suppression of centrally assessed Ki67 between the diagnostic biopsy sample (pre-treatment) and the surgical sample (post-treatment). The secondary objective is to evaluate safety and tolerability. Tertiary objectives include defining genes predictive of a reduction in Ki67, and evaluating the changes in ER, PR, AR, FoxA1, Cyclin D1, and apoptotic markers in breast tumors post-intervention. Accrual: This study opened in February 2018 and as of 13 July 2022, 164 patients have been enrolled. Target accrual is 200 patients. Contact information: This study is led at St Vincent’s Hospital Sydney, Australia, and funded by the Cancer Council of NSW and the NHMRC Translational Breast Cancer Project grant. Contact: Elgene Lim MBBS FRACP PhD at e.lim@garvan.org.au.

Citation Format: Teesha Downton, Davendra Segara, Andrew Ong, Janne Bingham, Emma-Kate Carson, Julia Chen, Kate Middleton, Geoffrey Lindeman, Andrew Parker, Elgene Lim. WinPro: A window of opportunity study of endocrine therapy with and without prometrium in postmenopausal women with early-stage hormone receptor-positive breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT2-01-10.

Abstract OT1-02-02: A phase 1/2 study to evaluate the safety and efficacy of EP0062, an oral Selective Androgen Receptor Modulator (SARM), for the treatment of AR+/HER2-/ER+ advanced breast cancer

There is growing interest in targeting the androgen receptor (AR) in advanced/metastatic breast cancer. It has been recently demonstrated preclinically that AR activation, rather than AR suppression, exerts potent antitumor activity across a number of ER+/AR+ breast tumors, including those resistant to standard-of-care endocrine therapy and CDK4/6 inhibitors (Hickey et al, Nature Medicine 2021 27: 310-320). Mechanistically, agonist activation of AR altered the genomic distribution of ER and essential co-activators resulting in repression of ER-regulated cell cycle genes and upregulation of AR target genes, including known tumor suppressors. EP0062 is an oral, non-steroidal, SARM currently being developed for the treatment of AR+/HER2-/ER+ advanced breast cancer. The efficacy and safety of EP0062 has previously been investigated in a Phase 1 clinical trial of AR+/HER2–/ER+ advanced breast cancer, and demonstrated that EP0062 has acceptable tolerability with evidence of clinical efficacy (LoRusso et al. Clinical Breast Cancer 2022 22;1 67-77). This new study is designed to further extend the evaluation of EP0062 as a potential therapy for AR+/HER2–/ER+ advanced breast cancer. The primary aim of the study is to assess tolerability and identify an optimal RP2D dose. The study will also explore the relationship between efficacy of EP0062 and AR expression, to establish a threshold for future patient selection, and undertake an initial evaluation of the safety and efficacy of EP0062 in combination with established standard of care therapies. The study will recruit up to 128 patients with AR+/HER2-/ER+ advanced breast cancer. Module A is a dose finding cohort to investigate safety, tolerability, PK and PD and to define the maximum tolerated dose (MTD) and/or Recommended Phase II Dose (RP2D). Dose finding will be based on a 3+3 design and is expected to recruit up to 32 patients. Once potential recommended doses are identified, approximately 60 evaluable patients will be randomised to two different dose cohorts in Module B in order to further optimise the RP2D dose, by further evaluation of safety and tolerability, as well as prospectively evaluate the relationship between efficacy and AR expression. In Module C, EP0062 will be combined with select standard of care targeted therapies in patients with relapsed AR+/HER2-/ER+ advanced breast cancer to confirm safety and explore efficacy. This will include approximately 36 patients across a number of single arm expansion cohorts. The key inclusion criteria are as follows: • Post-menopausal women, ≥18 years • ECOG performance status of 0 to 1 • Locally advanced or metastatic breast cancer • ER+, HER2- as per ASCO CAP guidelines • AR+, as defined as ≥ 10% AR nuclei staining by IHC • Endocrine-sensitive defined as greater than 3 years endocrine treatment prior to recurrence if recurrence occurred in the adjuvant setting, or ≥ 6 months treatment and response if recurrence occurred from primary treatment in the advanced setting • Relapsed, defined as clear and documented evidence of disease progression following ≥ 1 lines and ≤2 prior lines of previous endocrine therapy and ≤ 2 lines of chemotherapy in the advanced/metastatic setting • Measurable disease defined by RECIST version 1.1, or measurable bone-only disease EP0062 will be dosed to progression. Endpoints include incidence of DLTs during Cycle 1 of EP0062 treatment (28 days), MTD, RP2D (Module A), incidence and severity of AEs and SAEs, plasma PK parameters, Clinical Benefit Rate (complete response, partial response, or stable disease) at 24 weeks, ORR, duration of response, PFS, OS and quality of life. Clinic follow-up will be at 2 and 4 weeks, then every 4 weeks until disease progression. Recruitment is scheduled to initiate in Q4 2022.

Citation Format: Elgene Lim, Erika Hamilton, Carlo Palmieri, Hendrik-Tobias Arkenau, Sue Brook, Geoff Fisher, Andrew Mazur. A phase 1/2 study to evaluate the safety and efficacy of EP0062, an oral Selective Androgen Receptor Modulator (SARM), for the treatment of AR+/HER2-/ER+ advanced breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT1-02-02.

Abstract PD13-04: PD13-04 Exploratory subgroup and biomarker analyses of acelERA Breast Cancer: Phase II study of giredestrant (GDC-9545) vs physician’s choice of endocrine therapy for previously treated, estrogen receptor+, HER2– advanced breast cancer

BACKGROUND Endocrine therapy (ET) is the mainstay for management of estrogen receptor (ER)+ advanced breast cancer (aBC). Giredestrant is a highly potent, nonsteroidal, oral selective ER antagonist and degrader (SERD) that achieves robust ER occupancy. The Phase II randomized, open-label acelERA BC study (NCT04576455) evaluated giredestrant vs physician’s choice of ET (PCET) in the second- or third-line ER+, HER2– aBC setting. While the study did not reach statistical significance for its primary endpoint of investigator-assessed progression-free survival (INV-PFS), the giredestrant arm demonstrated a numerical improvement vs the PCET arm, with a hazard ratio of 0.81 (95% confidence interval: 0.60, 1.10), and encouraging results for key secondary efficacy endpoints (clinical benefit rate [CBR]: 32% vs 21%, respectively; objective response rate [ORR]: 13% vs 7%, respectively). We report exploratory subgroup analyses of these efficacy endpoints by prior treatments and by baseline circulating tumor (ct)DNA biomarkers.

METHODS Patients were post- and pre- or peri-menopausal women, or men, with ER+, HER2– aBC who had progressed after 1–2 lines of systemic therapy in the advanced setting (≤1 targeted agent; ≤1 chemotherapy regimen; prior fulvestrant allowed). Randomization was 1:1 to giredestrant (30 mg oral daily) or PCET between fulvestrant or an aromatase inhibitor (AI), stratified by disease site (visceral vs non-visceral), prior CDK4/6 inhibitor, and prior fulvestrant. Biomarkers were assessed in baseline ctDNA isolated from plasma using the FoundationOne Liquid CDx or PredicineCARE assays. ESR1 mutations were defined as short variants with known or likely impact on ER protein function.

RESULTS Among the 303 patients enrolled, prior aBC therapies included CDK4/6 inhibitors (42%), fulvestrant (19%), and chemotherapy (32%). Overall, most baseline characteristics were balanced across arms in subgroups. Efficacy in key subgroups by prior treatment and in ESR1-mutated tumors is shown in the table. Efficacy by PCET (75% received fulvestrant; 25%, an AI) and by type of ESR1 mutation will be presented. Clinical benefit (INV-PFS, CBR, ORR) was most prominently observed with giredestrant in patients with ESR1-mutated tumors. In the baseline ctDNA-evaluable population (232/303 patients; 77%), ESR1 and PIK3CA were the most prevalent mutations overall (39% and 36%, respectively). The most common ESR1 mutations were D538G, Y537S, Y537N, and E380Q; 54% of baseline ctDNA samples classified as ESR1-mutated had multiple ESR1 mutations detected (range of 2–7 mutations), demonstrating clonal heterogeneity. Clinical benefit was also observed with giredestrant in patients expressing different ESR1 mutations. Updated data will be presented.

CONCLUSIONS Exploratory subgroup analyses showed favorable outcomes with giredestrant in terms of INV-PFS, CBR, and ORR across most key subgroups. The benefit was more pronounced in a) patients with ESR1-mutated tumors and b) patients who received prior fulvestrant (the majority of AI-treated patients in the PCET arm). Overall, these data support continued investigation of giredestrant to advance and improve treatment outcomes in hormone receptor+ BC.

Table 1: Exploratory subgroup analyses

Citation Format: Elgene Lim, Marianna Chavez, Aditya Bardia, Joo Hyuk Sohn, Heather M. Moore, Mahesh Shivhare, Jorge Martinalbo, Laura Roncoroni, Pablo D. Perez-Moreno, Miguel Martín. PD13-04 Exploratory subgroup and biomarker analyses of acelERA Breast Cancer: Phase II study of giredestrant (GDC-9545) vs physician’s choice of endocrine therapy for previously treated, estrogen receptor+, HER2– advanced breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD13-04.

Abstract GS2-01: GS2-01 Trastuzumab deruxtecan vs physician’s choice in patients with HER2+ unresectable and/or metastatic breast cancer previously treated with trastuzumab emtansine: primary results of the randomized, phase 3 study DESTINY-Breast02

In DESTINY-Breast01 (NCT03248492) and DESTINY-Breast03 (NCT03529110), trastuzumab deruxtecan (T-DXd) demonstrated unprecedented activity in patients (pts) with HER2+ (immunohistochemistry 3+; immunohistochemistry 2+/in situ hybridization+) advanced metastatic breast cancer (mBC), leading to regulatory approvals in several countries for HER2+ unresectable/mBC after a prior anti–HER2-based regimen. DESTINY-Breast02 (NCT03523585) is a phase 3 trial of T-DXd vs treatment of physician’s choice (TPC) in patients with centrally confirmed HER2+ mBC previously treated with trastuzumab emtansine (T-DM1). It acts as a confirmatory study for the pivotal phase 2 DESTINY-Breast01 trial. Here we report the primary results of DESTINY-Breast02.

Methods: Pts with HER2+ mBC were randomized 2:1 to receive T-DXd or TPC (trastuzumab + capecitabine or lapatinib + capecitabine) and stratified by hormone receptor (HR) status (HR+/HR-), prior pertuzumab treatment, and history of visceral disease. The primary endpoint of this time-driven primary analysis was progression-free survival (PFS) as determined by blinded independent central review (BICR). The powered secondary endpoint was overall survival (OS). Other secondary endpoints included confirmed objective response rate (ORR) by BICR, duration of response (DoR) by BICR, PFS by investigator assessment, safety, and others.

Results: 608 pts were randomized to receive T-DXd (n = 406) or TPC (n = 202). Pts receiving T-DXd and TPC had a median age of 54.2 years (range, 22.4-88.5 years) and 54.7 years (range, 24.7-86.5 years), respectively, with a median of 2 (range, 0-10 and range,1-8) prior lines of systemic therapy (excluding hormone therapy) in the metastatic setting. Median treatment duration was 11.3 mo in the T-DXd arm and ~4.5 mo in the TPC arm. Efficacy and safety results are shown in the table below. T-DXd significantly improved PFS (HR, 0.36; 95% CI, 0.28-0.45; P &lt;0.000001) and OS (HR, 0.66; 95% CI, 0.50-0.86; P = 0.0021) compared with TPC. Confirmed ORR was 69.7% (14% complete response) with T-DXd and 29.2% (5.0% complete response) with TPC. Grade ≥3 treatment-emergent adverse events (TEAEs) occurred in 52.7% and 44.1% of pts receiving T-DXd and TPC, respectively. Adjudicated drug-related interstitial lung disease (ILD) occurred in 10.4% of pts with T-DXd vs 0.5% of pts with TPC. In pts receiving T-DXd, most ILD cases (88.1%) were grade 1/2 and grade 5 ILD was reported in 2 (0.5%) pts.

Conclusions: Results from DESTINY-Breast02 confirmed the clinical benefit and superiority of T-DXd over conventional chemotherapy-based regimens in pts with HER2+ mBC previously treated with T-DM1, as evidenced by significant and clinically meaningful improvements in PFS and OS. These data, together with earlier reported results from the DESTINY-Breast03 study of T-DXd vs T-DM1 solidify T-DXd as an optimal treatment option in pts with progressive HER2+ mBC across broad settings.

Editorial Acknowledgment

Under guidance of the authors, assistance in medical writing and editorial support was provided by Caylin Bosch, PhD, of ApotheCom, and was funded by Daiichi Sankyo.

Funding

This study was funded by Daiichi Sankyo and AstraZeneca.

Table. Summary of Efficacy and Safety Results for T-DXd and TPC in Patients With HER2+ mBC Previously Treated With T-DM1

Citation Format: Ian Krop, Yeon H. Park, Sung-Bae Kim, Giuliano Borges, Sercan Aksoy, Joaquin Gavila Gregori, Rebecca Roylance, Elgene Lim, Rinat Yerushalmi, Flora Zagouri, Francois P. Duhoux, Tanja Fehm, Toshimi Takano, Anton Egorov, Iris Wu, Jillian Cathcart, Changan Chu, Fabrice Andre. GS2-01 Trastuzumab deruxtecan vs physician’s choice in patients with HER2+ unresectable and/or metastatic breast cancer previously treated with trastuzumab emtansine: primary results of the randomized, phase 3 study DESTINY-Breast02 [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS2-01.

Abstract OT2-10-05: HER2Pro: A Phase 1b dose de-escalation study of high dose prochlorperazine added to paclitaxel, trastuzumab and pertuzumab in patients with previously untreated HER2-positive metastatic breast cancer

HER2Pro: A Phase 1b dose de-escalation study of high dose prochlorperazine added to paclitaxel, trastuzumab and pertuzumab in patients with previously untreated HER2-positive metastatic breast cancer Authors Teesha Downton1,2, Emma Karlsen1, Katharine Cuff3,4, Euan Walpole3,4, Fiona Simpson3,4, Elgene Lim1,2. Affiliations 1Garvan Institute of Medical Research, Darlinghurst NSW, Australia; 2School of Clinical Medicine, St Vincent’s Healthcare Clinical Campus, Faculty of Medicine and Health, University of New South Wales Sydney, Australia; 3Diamantina Institute, University of Queensland, Woolloongabba QLD, Australia; 4Princess Alexandra Hospital, Brisbane QLD, Australia Disclosures T. Downton: None. E. Karlsen: None. K. Cuff: None. E. Walpole: None. F. Simpson: None. E. Lim. Advisory Board for Pfizer, Astra Zeneca, Lilly, Roche, Novartis, Gilead Australia. Research Funding from Pfizer, Novartis, Bayer. Abstract Background: The anti-emetic prochlorperazine reversibly inhibits dynamin-mediated endocytosis. Preclinical studies have demonstrated that through this mechanism, high dose prochlorperazine can temporarily increase tumor cell antigen presentation, enhance interaction of tumor antigens with therapeutic monoclonal antibodies, and improve antibody-dependent cellular cytotoxicity (Chew H et al. Cell 2020). High dose prochlorperazine has been well tolerated and proof of mechanism demonstrated in a pilot study (ACTRN12619001051134), and in a phase Ib trial (ACTRN12619001527156) of prochlorperazine with cetuximab in patients with EGFR-expressing advanced head and neck squamous cell carcinoma or breast cancer. Prochlorperazine potentially offers a novel approach to improve the efficacy of a range of therapeutic antibodies. This study HER2Pro (ACTRN12622000016730) aims to evaluate the feasibility and safety of high dose prochlorperazine in combination with paclitaxel, trastuzumab, and pertuzumab in patients with HER2-positive metastatic breast cancer. Trial Design: In this phase Ib single-arm trial, patients receive standard of care trastuzumab and pertuzumab 3-weekly and paclitaxel weekly. From cycle 2, patients in addition receive de-escalating doses of prochlorperazine weekly for 6 weeks, though an additional 6 weeks may be given if there are no treatment associated serious adverse events. Dose de-escalation will be evaluated using a 3+3 design, commencing at a prochlorperazine intravenous dose of 0.8mg/kg weekly. Eligibility: Eligible patients must have previously untreated HER2-positive metastatic breast cancer, Eastern Cooperative Oncology Group performance status 0-1, and baseline left ventricular ejection fraction 50%. Key exclusion criteria include current daily treatment with corticosteroids at a dose &gt;10mg prednisolone or equivalent, blood pressure &lt; 90/50 mmHg, prolonged QT interval, and Parkinson’s disease. Objectives: The primary objective is to determine the recommended phase 2 dose. Secondary objectives include determining the frequency and severity of adverse events, rates of cardiotoxicity, objective response rate, duration of response and progression free survival. Tertiary objectives include analysis of receptor trafficking and immune system activation on paired tumor biopsies obtained before and after first prochlorperazine dose. Accrual: 6-12 patients will be enrolled across 2 Australian sites. Enrollment for this trial is expected to commence late 2022.

Citation Format: Teesha Downton, Emma Karlsen, Katharine Cuff, Euan Walpole, Fiona Simpson, Elgene Lim. HER2Pro: A Phase 1b dose de-escalation study of high dose prochlorperazine added to paclitaxel, trastuzumab and pertuzumab in patients with previously untreated HER2-positive metastatic breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT2-10-05.

Real-World Outcomes of Ribociclib and Aromatase Inhibitor Use in First Line Hormone Receptor Positive, HER2-Negative Metastatic Breast Cancer

BACKGROUND

International guidelines recommend combining a CDK4/6 inhibitor and endocrine therapy (ET) as first line treatment for hormone receptor (HR) positive, HER2 negative metastatic breast cancer (MBC). Results from MONALEESA-2 demonstrate superior progression free survival (PFS) and overall survival (OS) with ribociclib (CDK4/6 inhibitor) and ET compared to ET alone. Real world outcomes have yet to be reported.

MATERIALS AND METHODS

KARMA is a non-interventional registry of Australian patients receiving first-line treatment with ribociclib and aromatase inhibitor (AI), obtained via a Medicine Access Program (MAP) for HR+, HER2- MBC. Outcomes were compared with the ribociclib/letrozole cohort in MONALEESA-2.

RESULTS

Data from 160 patients at 17 sites was analysed. Median follow-up is 36.5 months. Compared to MONALEESA-2, patients were numerically younger (54.3 vs. 62 years), with higher rates of bone-only metastases (31% vs. 21%). A total of 63 of 160 (39%) patients remain on treatment. A total of 56% of patients had at least 1 dose reduction, with neutropenia (68%) and abnormal liver enzymes (17%) the most common reasons. A total of 17 of 160 (11%) discontinued treatment due to toxicity, with no treatment related deaths. Median PFS was not reached (95% CI 29.9- NR), with PFS at 12 months and 18 months being 76% and 67% respectively versus 25.3 months, 73% and 63% in MONALEESA-2.

CONCLUSION

The ribociclib and AI combination was well tolerated in this real-world setting. The KARMA registry cohort achieved a superior PFS (>36.5 months) to MONALEESA-2, potentially due to more favourable baseline disease characteristics. Less frequent assessment scheduling in this non trial setting may also contribute.

Short-term risk prediction after major lower limb amputation: PERCEIVE study

BACKGROUND

The accuracy with which healthcare professionals (HCPs) and risk prediction tools predict outcomes after major lower limb amputation (MLLA) is uncertain. The aim of this study was to evaluate the accuracy of predicting short-term (30 days after MLLA) mortality, morbidity, and revisional surgery.

METHODS

The PERCEIVE (PrEdiction of Risk and Communication of outcomE following major lower limb amputation: a collaboratIVE) study was launched on 1 October 2020. It was an international multicentre study, including adults undergoing MLLA for complications of peripheral arterial disease and/or diabetes. Preoperative predictions of 30-day mortality, morbidity, and MLLA revision by surgeons and anaesthetists were recorded. Probabilities from relevant risk prediction tools were calculated. Evaluation of accuracy included measures of discrimination, calibration, and overall performance.

RESULTS

Some 537 patients were included. HCPs had acceptable discrimination in predicting mortality (931 predictions; C-statistic 0.758) and MLLA revision (565 predictions; C-statistic 0.756), but were poor at predicting morbidity (980 predictions; C-statistic 0.616). They overpredicted the risk of all outcomes. All except three risk prediction tools had worse discrimination than HCPs for predicting mortality (C-statistics 0.789, 0.774, and 0.773); two of these significantly overestimated the risk compared with HCPs. SORT version 2 (the only tool incorporating HCP predictions) demonstrated better calibration and overall performance (Brier score 0.082) than HCPs. Tools predicting morbidity and MLLA revision had poor discrimination (C-statistics 0.520 and 0.679).

CONCLUSION

Clinicians predicted mortality and MLLA revision well, but predicted morbidity poorly. They overestimated the risk of mortality, morbidity, and MLLA revision. Most short-term risk prediction tools had poorer discrimination or calibration than HCPs. The best method of predicting mortality was a statistical tool that incorporated HCP estimation.

Oral Selective Estrogen Receptor Degraders (SERDs) in Breast Cancer: Advances, Challenges, and Current Status

Several endocrine therapies are currently available for the treatment of estrogen receptor (ER) positive breast cancer, but the clinical benefit of these agents is limited by endocrine therapy drug resistance. A common mechanism of endocrine therapy resistance is ESR1 mutations. The first-generation selective estrogen receptor degrader (SERD) fulvestrant has activity against ESR1 mutant tumors but requires intramuscular injection and has poor bioavailability that precludes optimal drug dosing. This led to the development of second-generation SERDs which are potent and have improved oral bioavailability and pharmacokinetics. Several of these oral SERDs are now in phase III trials in both the early and advanced ER positive breast cancer settings. This review summarizes the background of oral SERD development, the current status and future perspectives.

Temporal profiling of the breast tumour microenvironment reveals collagen XII as a driver of metastasis

The tumour stroma, and in particular the extracellular matrix (ECM), is a salient feature of solid tumours that plays a crucial role in shaping their progression. Many desmoplastic tumours including breast cancer involve the significant accumulation of type I collagen. However, recently it has become clear that the precise distribution and organisation of matrix molecules such as collagen I is equally as important in the tumour as their abundance. Cancer-associated fibroblasts (CAFs) coexist within breast cancer tissues and play both pro- and anti-tumourigenic roles through remodelling the ECM. Here, using temporal proteomic profiling of decellularized tumours, we interrogate the evolving matrisome during breast cancer progression. We identify 4 key matrisomal clusters, and pinpoint collagen type XII as a critical component that regulates collagen type I organisation. Through combining our proteomics with single-cell transcriptomics, and genetic manipulation models, we show how CAF-secreted collagen XII alters collagen I organisation to create a pro-invasive microenvironment supporting metastatic dissemination. Finally, we show in patient cohorts that collagen XII may represent an indicator of breast cancer patients at high risk of metastatic relapse.

The distribution and organisation of matrix molecules in the tumour stroma help shape solid tumour progression. Here they perform temporal proteomic profiling of the matrisome during breast cancer progression and show that collagen XII secreted from CAFs provides a pro-invasive microenvironment.

Pan-Asian adapted ESMO Clinical Practice Guidelines for the diagnosis, treatment and follow-up of patients with prostate cancer

The most recent version of the European Society for Medical Oncology (ESMO) Clinical Practice Guidelines for the diagnosis, treatment and follow-up of prostate cancer was published in 2020. It was therefore decided, by both the ESMO and the Singapore Society of Oncology (SSO), to convene a special, virtual guidelines meeting in November 2021 to adapt the ESMO 2020 guidelines to take into account the differences associated with the treatment of prostate cancer in Asia. These guidelines represent the consensus opinions reached by experts in the treatment of patients with prostate cancer representing the oncological societies of China (CSCO), India (ISMPO), Japan (JSMO), Korea (KSMO), Malaysia (MOS), Singapore (SSO) and Taiwan (TOS). The voting was based on scientific evidence and was independent of the current treatment practices and drug access restrictions in the different Asian countries. The latter were discussed when appropriate. The aim is to provide guidance for the optimisation and harmonisation of the management of patients with prostate cancer across the different regions of Asia.

Vessel wall magnetic resonance and arterial spin labelling imaging in the management of presumed inflammatory intracranial arterial vasculopathy

Optimal criteria for diagnosing and monitoring response to treatment for infectious and inflammatory medium–large vessel intracranial vasculitis presenting with stroke are lacking. We integrated intracranial vessel wall MRI with arterial spin labelling into our routine clinical stroke pathway to detect presumed inflammatory intracranial arterial vasculopathy, and monitor disease activity, in patients with clinical stroke syndromes. We used predefined standardized radiological criteria to define vessel wall enhancement, and all imaging findings were rated blinded to clinical details. Between 2017 and 2018, stroke or transient ischaemic attack patients were first screened in our vascular radiology meeting and followed up in a dedicated specialist stroke clinic if a diagnosis of medium–large inflammatory intracranial arterial vasculopathy was radiologically confirmed. Treatment was determined and monitored by a multi-disciplinary team. In this case series, 11 patients were managed in this period from the cohort of young stroke presenters (<55 years). The median age was 36 years (interquartile range: 33,50), of which 8 of 11 (73%) were female. Two of 11 (18%) had herpes virus infection confirmed by viral nucleic acid in the cerebrospinal fluid. We showed improvement in cerebral perfusion at 1 year using an arterial spin labelling sequence in patients taking immunosuppressive therapy for >4 weeks compared with those not receiving therapy [6 (100%) versus 2 (40%) P = 0.026]. Our findings demonstrate the potential utility of vessel wall magnetic resonance with arterial spin labelling imaging in detecting and monitoring medium–large inflammatory intracranial arterial vasculopathy activity for patients presenting with stroke symptoms, limiting the need to progress to brain biopsy. Further systematic studies in unselected populations of stroke patients are needed to confirm our findings and establish the prevalence of medium–large artery wall inflammation.

64Cu-SAR-Bombesin PET-CT Imaging in the Staging of Estrogen/Progesterone Receptor Positive, HER2 Negative Metastatic Breast Cancer Patients: Safety, Dosimetry and Feasibility in a Phase I Trial

Breast cancers are most frequently oestrogen receptor (ER) and progesterone receptor (PR) positive and [18F]Fluorodeoxyglucose PET-CT (FDG) has lower sensitivity for these subtypes. The gastrin-releasing peptide receptor (GRPR) is overexpressed in ER+/PR+ breast cancers. This study assessed the safety and potential of [64Cu]Cu-Sarcophagine (SAR)-Bombesin PET/CT (BBN) in re-staging metastatic ER+/PR+/human epidermal growth-factor-2-negative (HER2-) breast cancer. Seven patients with metastatic ER+/PR+/HER2- breast cancer undergoing staging underwent [64Cu]Cu-SAR-BBN PET-CT. Bloods, vital signs and electrocardiogram, blood tracer-clearance and dosimetry were undertaken. GRPR status was assessed in available metastatic biopsy samples. Staging with conventional imaging ([18F]FDG, bone scan and diagnostic CT) was within 3 weeks of [64Cu]Cu-SAR-BBN PET/CT. PET scans were assessed visually and quantitatively. Seven patients underwent imaging. One of the seven had de-novo metastatic breast cancer and six of the seven recurrent metastatic disease. Two of the seven had lobular subtype. No adverse events were reported. All seven patients were positive on conventional imaging (six of seven on FDG). [64Cu]Cu-SAR-BBN imaging was positive in five of the seven. Both [64Cu]Cu-SAR-BBN-negative patients had disease identified on [18F]FDG. One patient was [64Cu]Cu-SAR-BBN positive/[18F]FDG negative. Four of seven patients were [64Cu]Cu-SAR-BBN positive/[18F]FDG positive. In these four, mean SUVmax was higher for [64Cu]Cu-SAR-BBN than [18F]FDG (SUVmax 15 vs. 12). In the classical lobular subtype (two of seven), [64Cu]Cu-SAR-BBN was more avid compared to [18F]FDG (SUVmax 20 vs. 11, and 20 vs. <3). Dosimetry calculations estimated whole-body effective dose for 200 MBq of [64Cu]Cu-SAR-BBN to be 1.9 mSv. [64Cu]Cu-SAR-BBN PET/CT appears safe and may have diagnostic value in metastatic ER+/PR+/HER2- breast cancer, particularly the lobular subtype. Further evaluation is warranted.

64Cu-SAR-Bombesin PET-CT imaging in the staging of ER+/PR+/HER2- metastatic breast cancer: Safety, dosimetry, and feasibility in a phase I trial

3092

Background: Breast cancers are most frequently oestrogen receptor (ER) and progesterone receptor (PR) positive and 18F-Fluorodeoxyglucose PET-CT (FDG) used in conventional staging of breast cancer has lower sensitivity for these subtypes. Gastrin releasing peptide receptors (GRPR) are a potential alternative diagnostic and theranostic target for ER+/PR+ breast cancers due to their overexpression of GRPR. This phase 1 study aims to assess the safety and potential of the novel radiotracer 64Cu-Sarcophagine(SAR)-Bombesin (BBN) in the re-staging of recurrent metastatic ER+/PR+/human epidermal growth factor 2 negative (HER2-) breast cancer. Methods: Patients with confirmed recurrent or primary metastatic ER+/PR+/HER2- breast cancer undergoing staging prior to a new treatment underwent 64Cu-SAR-BBN PET-CT with imaging at 1, 3 and 24 hours post-injection. Bloods and vital signs were acquired for patients at baseline, 1, 3 and 24 hours post-injection timepoints, and electrocardiogram (ECG) performed 1 hour pre and 1 hour post injection. Blood tracer-clearance and dosimetry was performed. GRPR receptor status was assessed in 4/7 patients from metastatic-site biopsy samples. Staging of the patients was assessed by conventional imaging (FDG, bone scan and diagnostic CT) within 3 weeks of 64Cu-SAR-BBN imaging. All PET scans were assessed visually, and quantitatively using MIM Software. Results: 9 patients were enrolled. 7/9 patients underwent all imaging modalities, while 2/9 did not undergo BBN imaging. 1/7 patient who underwent all imaging had de- novo metastatic ER+/PR+/Her 2- breast cancer and 6/7 recurrent metastatic disease. 2/7 had lobular subtype. There were no adverse events reported, and ECG, vitals and haematological, biochemical and coagulation markers remained unchanged. All 7 patients were positive on conventional imaging, while 6/7 were positive on FDG. BBN was positive in 5/7 patients. Both BBN negative patients had disease identified on FDG. Conversely, 1 patient was BBN positive but FDG negative. 4/7 patients were BBN positive and FDG positive. In these 4 patients, mean SUVmax was higher for BBN than FDG (15 vs. 12). In classical lobular subtype (2/7), BBN was highly avid compared to FDG (SUV max 20 vs 11, and 20 vs <3) and with a higher tumor volume compared to FDG (2034 vs 504, and 634 mL vs FDG negative). Conclusions: 64Cu-SAR-Bombesin is a novel tracer which appears safe and may have a diagnostic and theranostic role in patients with metastatic ER+/PR+/HER2- breast cancer, particularly lobular subtype. Further evaluation appears warranted.

Phase 3 ENABLAR-2 study to evaluate enobosarm and abemaciclib combination compared to estrogen-blocking agent for the second-line treatment of AR+, ER+, HER2- metastatic breast cancer in patients who previously received palbociclib and estrogen-blocking agent combination therapy

TPS1121

Background: Targeting the androgen receptor (AR) may be the next important endocrine therapy for advanced breast cancer. The AR has been demonstrated to be a tumor suppressor when activated. Enobosarm is an oral selective AR targeting agonist that activates the AR in breast cancer. Preclinical studies in CDK4/6 inhibitor resistant PDX models demonstrated combinatorial synergistic activity of enobosarm plus CDK 4/6 inhibitors. An open-label, Phase 2 study, was conducted in 136 women with heavily pretreated ER+ HER2- metastatic breast cancer that were randomized to oral daily enobosarm at a dose of 9 or 18 mg. The efficacy evaluable (EE) group were patients that were AR positive (> 10% AR nuclear staining). In the EE population with measurable disease at baseline, 10 patients had received prior endocrine therapy + a CDK 4/6 inhibitor. Subsequent treatment with enobosarm resulted in a clinical benefit rate of 50% and the best overall response rate (ORR) was 30% (2CRs and 1 PR). Of the 10 patients, 7 had AR nuclear staining ≥40%. None of the patients with AR nuclear staining < 40% responded to enobosarm. Although a small subset of the study, it appears that enobosarm has activity in patients who had ≥40% AR staining and who had progressed on standard endocrine therapy with a CDK 4/6 inhibitor. Overall, treatment with enobosarm was well tolerated with significant positive effects on quality-of-life measurements. Methods: The ENABLAR-2 trial is an ongoing Phase 3, randomized, open-label, efficacy and safety study in patients with AR+ ER+ HER2- MBC with AR nuclear staining of ≥40%, who have progressed after one line of systemic therapy comprising estrogen blocking agent and palbociclib. The planned sample size is 186 patients randomized 1:1 to enobosarm + abemaciclib OR fulvestrant if the first line of therapy for MBC was a non-steroidal AI plus palbociclib, until disease progression, toxicity, or loss of clinical benefit. If first line therapy for metastatic breast cancer was fulvestrant plus palbociclib, then the patient will be randomized 1:1 to either enobosarm + abemaciclib OR an AI. Randomization will be stratified by AR% nuclear staining, ≥60% versus < 60%, as well as by estrogen blocking agent such that each cohort will have the same number of subjects previously receiving fulvestrant + palbociclib in first line therapy. The key objectives are to determine the safety and efficacy of enobosarm and abemaciclib combination versus an alternative estrogen blocking agent with the primary endpoint of PFS. Secondary endpoints include ORR, duration of response, overall survival, change from baseline in Short Physical Performance Battery (SPPB), change in EORTC Quality of Life Questionnaire (EORTC-QLQ) and change in body composition as measured by DEXA. Clinical trial information: NCT05065411.

A phase 1a/b trial of imlunestrant (LY3484356), an oral selective estrogen receptor degrader (SERD) in ER-positive (ER+) advanced breast cancer (aBC) and endometrial endometrioid cancer (EEC): Monotherapy results from EMBER

1021

Background: Imlunestrant is a novel, orally bioavailable SERD with pure antagonistic properties that result in sustained inhibition of ER-dependent gene transcription and cell growth. In dose escalation, imlunestrant showed favorable safety, pharmacokinetics (PK) and preliminary efficacy in patients with ER+, HER2- aBC and ER+ EEC (Phase 1a EMBER, Jhaveri 2021). Here we present updated data from the dose escalation (Phase 1a) and dose expansion (Phase 1b) of imlunestrant monotherapy in EMBER (NCT04188548). Methods: Phase 1a/1b enrolled patients with ER+ aBC (prior ET sensitivity; ≤3 prior therapies for aBC in Phase 1a following protocol amendment and ≤2 in Phase 1b) and ER+ EEC (prior platinum therapy; no prior fulvestrant or aromatase inhibitor). Premenopausal women received a concomitant GnRH agonist. Serial plasma samples were obtained for PK and ctDNA analysis. Key endpoints included recommended phase 2 dose (RP2D) determination, safety and tolerability, PK, objective response rate per RECIST v1.1 (ORR: complete response [CR] or partial response [PR]) in patients with measurable disease and ≥1 post-baseline tumor assessment or discontinued prior to tumor assessment, and clinical benefit rate (CBR: CR or PR, or stable disease ≥24 weeks) in patients enrolled ≥24 weeks prior to data cut. Results: As of January 14, 2022, 138 patients (n = 114 aBC, n = 24 EEC) received imlunestrant monotherapy at doses ranging from 200-1200 mg QD. Median age was 62.0 years (range 32-95). Median number of prior therapies for aBC and EEC was 2 (range 0-8) and 1 (0-5), respectively. aBC patients had received a prior ET (94.7%), CDK4/6 inhibitor (92.1%), fulvestrant (50.9%) and chemotherapy (26.3%). No dose-limiting toxicities were observed. Most treatment-emergent adverse events (TEAEs) were grade 1. At the RP2D (400 mg QD, n= 69), the most common all grade TEAE’s were nausea (33.3%), fatigue (27.5%), and diarrhea (23.2%). Across all doses, the incidence of treatment-related grade 3 AEs was low (3.6%). No patient discontinued due to a TEAE. In evaluable aBC patients, ORR was 8.0% (6/75) and CBR was 40.4% (42/104). In evaluable EEC patients, ORR was 5.0% (1/20 had a PR- ongoing pending confirmation) and CBR was 47.1% (8/17). Clinical benefit was observed regardless of baseline ESR1 mutation status as determined by ctDNA sequencing. Additional biomarker analyses will be presented at the meeting. Conclusions: Imlunestrant continues to demonstrate a favorable side effect profile, with no cardiac or opthalmic safety signals, and has continued evidence of clinical activity in heavily pre-treated ER+ aBC and EEC patients. Clinical trial information: NCT04188548.

Paracrine IL-6 Signaling Confers Proliferation between Heterogeneous Inflammatory Breast Cancer Sub-Clones

Simple Summary

This study provides novel mechanistic insights into the capacity of the inflammatory cytokine IL-6 and its associated STAT3-dependent signaling pathway to stimulate proliferation in trans between individual sub-clones in a model of heterogeneity in inflammatory breast cancer. The clinical relevance of this discovery is provided by our observation that proliferation of the IL-6 responsive subclone is sensitive to inhibition with the clinically approved anti-IL-6 receptor humanized monoclonal antibody Tocilizumab. These findings therefore provide a rationale for potentially repurposing Tocilizumab for the treatment of a subset of inflammatory breast cancer patients.

Abstract

Inflammatory breast cancer (IBC) describes a highly aggressive form of breast cancer of diverse molecular subtypes and clonal heterogeneity across individual tumors. Accordingly, IBC is recognized by its clinical signs of inflammation, associated with expression of interleukin (IL)-6 and other inflammatory cytokines. Here, we investigate whether sub-clonal differences between expression of components of the IL-6 signaling cascade reveal a novel role for IL-6 to mediate a proliferative response in trans using two prototypical IBC cell lines. We find that SUM149 and SUM 190 cells faithfully replicate differential expression observed in a subset of human IBC specimens between IL-6, the activated form of the key downstream transcription factor STAT3, and of the HER2 receptor. Surprisingly, the high level of IL-6 produced by SUM149 cells activates STAT3 and stimulates proliferation in SUM190 cells, but not in SUM149 cells with low IL-6R expression. Importantly, SUM149 conditioned medium or co-culture with SUM149 cells induced growth of SUM190 cells, and this effect was abrogated by the IL-6R neutralizing antibody Tocilizumab. The results suggest a novel function for inter-clonal IL-6 signaling in IBC, whereby IL-6 promotes in trans proliferation of IL-6R and HER2-expressing responsive sub-clones and, therefore, may provide a vulnerability that can be exploited therapeutically by repurposing of a clinically approved antibody.

321 Surgery Induction Guidebook – an Aid to a Successful Transition

Aim

There is a 4–12% increase in mortality following the August change over in the National Health Service (NHS) UK. A well-structured induction programme is mandatory to improve both the competency and confidence of new junior doctors. This activity was designed to evaluate and improve the induction process in Pilgrim Hospital by introducing an induction guidebook. It aimed to provide a sustainable and reliable source of information to junior doctors.

Method

An initial survey in the department assessed the needs and identified the information required for the guidebook. An induction guidebook was designed and circulated during the changeover. A feedback survey was conducted after the six months of the initial Induction guidebook release, to know the usefulness of components of the induction guidebook and identify any gaps to improve the guidebook.

Results

A total of 15 participants completed the feedback survey. 47% (7) found the induction guidebook beneficial and 53.3 % (8) found it ‘slightly beneficial'. Similarly, only 1 participant (6.7%) rated the guidebook to be “of minor importance”, while 53% (8) rating it “very important” part of induction. The feedback for the contents of the book was also encouraging with suggestions.

Conclusions

The guidebook proved to be a valuable source in helping new doctors during times of transition to adjust to the local system and improve the induction process. It provided information about local guidelines, job overview, team structure, IT, useful contacts, and other relevant information. We recommend the departmental guidebook as a vital part of local departmental induction during the changeover.

Abstract PD13-07: Activity and biomarker analyses from a phase Ia/b study of giredestrant (GDC-9545; G) with or without palbociclib (palbo) in patients with estrogen receptor-positive, HER2-negative locally advanced/metastatic breast cancer (ER+/HER2- LA/mBC)

Background A mainstay of ER+ BC treatment is to target ER activity and/or estrogen synthesis; however, during or after endocrine therapy (ET), many patients either relapse or develop resistance to such treatments due to several mechanisms, including ESR1 mutations which can be drivers of estrogen-independent transcription and proliferation. The majority of tumors remain dependent on ER signaling, and it is possible that patients will be responsive to second- or third-line ET after they have progressed on previous therapies. The highly potent, nonsteroidal oral selective ER antagonist and degrader G achieves robust ER occupancy and is active in patients with either ESR1-wildtype or -mutant tumors and in patients who had previously been treated with ET. G was well tolerated as a single agent and in combination with palbo, with antitumor activity shown in the nonrandomized, open-label, dose-escalation and -expansion, phase Ia/b GO39932 study (NCT03332797). We present updated activity and biomarker analyses in patients treated with 30 mg G monotherapy and those treated with 100 mg G + 125 mg palbo ± luteinizing hormone-releasing hormone (LHRH) agonists (clinical cutoff: Apr 16, 2021); 30 mg has since been selected as the dose in both the single agent and combination settings. Methods Eligible patients had ≤2 prior therapies for LA/mBC, disease recurrence, or progression while on adjuvant ET for ≥24 months and/or ET for LA/mBC, and tumor response or stable disease ≥6 months. All were postmenopausal (premenopausal women were allowed co-administered LHRH agonists with 100 mg G). Oral G was given daily on Days (D)1-28 of each 28-day cycle (C); 125 mg palbo, on a 21-day on/7-day off schedule. Modulation of ER signaling and proliferation of paired pre- and on-treatment (C2D8) tumor biopsies were assessed with immunohistochemistry for ER, progesterone receptor (PgR), and the proliferation marker Ki67, as well as with gene expression analysis of a predefined set of 38 ER target genes using the Illumina TruSeq RNA Access method. Plasma samples collected pre- and on-treatment (C1D15 and/or C2D1) were assessed for circulating tumor (ct)DNA using a digital PCR BEAMing assay detecting a total of 22 mutations across ESR1, AKT1, and PIK3CA. Results Objective response rates in patients with measurable disease at baseline were 20.0% in the 30 mg G group (6/30 patients) and 47.7% in the 100 mg G + palbo ± LHRH (combination) group (21/44). Clinical benefit rates were 55.0% (22/40 patients) and 81.3% (39/48), respectively. Overall, 21 pre- and on-treatment-paired tumor biopsies were collected in the 30 mg (n=13) and combination (n=8) groups. Consistent downregulation of ER, PgR, Ki67, and ER pathway activity was observed at C2D8, regardless of clinical benefit or baseline ESR1 mutation, demonstrating consistent on-target activity of G. Stronger Ki67, ER, and PgR suppression was seen with the addition of palbo to G. Of the 36 patients across both cohorts with a detectable ctDNA baseline ESR1 mutation, 16 had &gt;1 baseline ESR1 mutation. Of the eight unique ESR1 mutations detected, none showed an association with response. At C2D1, 34 patients had a decrease in ESR1 ctDNA levels from baseline, of which 27 became undetectable for ESR1 ctDNA. Early changes in PIK3CA and AKT1 ctDNA levels, but not ESR1, trended with response. Conclusions Encouraging clinical activity was observed with single agent G at 30 mg and with G at 100 mg in combination with palbo. Biomarker analyses demonstrated consistent biologic activity of G, and largely consistent decreases of ESR1 ctDNA levels. Further updated activity and biomarker data, including PAM50 subtype classifications, will be presented.

Citation Format: Nicolas C Turner, Sherene Loi, Heather M Moore, Ching-Wei Chang, Jennifer Eng-Wong, Aditya Bardia, Valentina Boni, Joohyuk Sohn, Komal L Jhaveri, Elgene Lim. Activity and biomarker analyses from a phase Ia/b study of giredestrant (GDC-9545; G) with or without palbociclib (palbo) in patients with estrogen receptor-positive, HER2-negative locally advanced/metastatic breast cancer (ER+/HER2- LA/mBC) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD13-07.

Abstract PD2-02: Combination CDK4/6 inhibition and AR agonism suppresses the growth of CDK4/6 inhibitor resistant breast cancers

Resistance to standard-of care-therapies is a significant clinical challenge in estrogen receptor positive (ER+) breast cancer. Cyclin dependent kinase 4/6 inhibitors (CDK4/6i) in combination with endocrine therapies (ET) is the current standard-of-care for advanced metastatic ER+ breast cancer; however, resistance to this combination is considered inevitable, leading to disease progression. The androgen receptor (AR) is expressed in up to 90% of all ER+ breast cancers, and has been associated with better patient outcome. Compelling recent pre-clinical data demonstrates that selective androgen receptor AR modulators (SARMs) act to suppress ER-driven tumour growth of endocrine-sensitive and -resistant models of ER+ breast cancer. Furthermore, a recent clinical trial evaluating the efficacy of SARMs has shown clinical benefit in patients with ER+/AR+ metastatic breast cancer (NCT02463032). We hypothesise that the SARMS, either alone or in combination with a CDK4/6i, would be an effective treatment for tumours that are sensitive and resistant to ET and CDK4/6i. We report therapeutic efficacy of combination AR agonism + CDK4/6i in CDK4/6-naïve and -resistant pre-clinical models, including cell lines and patient derived xenograft (PDX) models. We demonstrate that combination SARM + CDK4/6i potently and durably inhibited in vitro and in vivo tumour growth. Additionally, we provide evidence that in vivo treatment with the CDK4/6i Palbociclib increased AR expression and signalling, highlighting an interaction of the two signalling pathways not previously described. In conclusion, our data provides a pre-clinical rationale for combination SARM + CDK4/6i in CDK4/6i resistant ER+ breast cancer.

Citation Format: Allegra Freelander, Geraldine Laven-Law, Leila Eshraghi, Kee Ming Chia, Marie Pickering, Aliza Yong, Ashleigh Wilkinson, Sarah Alexandrou, C. Elizabeth Caldon, Theresa E Hickey, Wayne D Tilley, Elgene Lim. Combination CDK4/6 inhibition and AR agonism suppresses the growth of CDK4/6 inhibitor resistant breast cancers [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD2-02.

Effects of Endocrine Therapy on Cognitive Function in Patients with Breast Cancer: A Comprehensive Review

Simple Summary

Many persons diagnosed with breast cancer are treated with endocrine therapy and will experience the side effects of endocrine therapy. Cognitive adverse effects of endocrine therapy are increasingly being recognised, and can significantly affect quality of life, adherence and treatment outcome. This review aims to discuss the nature of cognitive dysfunction associated with endocrine therapy, the mechanisms underpinning its development, and evidence-based management strategies.

Abstract

Endocrine therapy forms the backbone of systemic therapy for the majority of persons with early and late-stage breast cancer. However, the side effects can negatively affect quality of life, and impact treatment adherence and overall oncological outcomes. Adverse effects on cognition are common, underreported and challenging to manage. We aim to describe the nature, incidence, risk factors and underlying mechanisms of endocrine therapy-induced cognitive dysfunction. We conducted a comprehensive literature review of the studies reporting on cognitive dysfunction associated with endocrine therapies for breast cancer. We also summarise prevention and treatment strategies, and ongoing research. Given that patients are taking endocrine therapies for longer durations than ever before, it is essential that these side effects are managed pro-actively within a multi-disciplinary team in order to promote adherence to endocrine therapy and improve patients’ quality of life.

Vascular inflammation in patients with obstructive sleep apnoea and coronary artery disease shown on coronary computed tomography angiography attenuation

Funding Acknowledgements

Type of funding sources: None.

Introduction

Obstructive sleep apnoea (OSA) is associated with increased plaque burden in coronary artery disease (CAD), but the role of vascular inflammation in this relationship is unclear. Coronary computed tomography angiography (CTA) enables surrogate assessment of systemic inflammation via subcutaneous adipose tissue attenuation (ScAT-a), and of coronary inflammation via epicardial adipose tissue volume and attenuation (EAT-v and EAT-a) and pericoronary adipose tissue attenuation (PCAT-a).

Purpose

To investigate whether vascular inflammation is increased in patients with severe OSA and high plaque burden.

Methods

Patients with clinically indicated polysomnography and coronary CTA were included. Severe OSA was classified as apnoea/hypopnoea index (AHI) &gt;30. High plaque burden was defined as a CT-Leaman score (CT-LeSc) &gt;8.3. Patients with both severe OSA and high plaque burden were defined as ‘Group 1’, all other patients were classified as ‘Group 2’. ScAT-a, EAT-a, EAT-v and PCAT-a were assessed on semi-automated software.

Results

A total of 91 patients were studied (59.3 ± 11.1 years). Severe OSA was associated with high plaque burden (p = 0.02). AHI correlated with CT-LeSc (r = 0.24, p = 0.023). Group 1 had lower EAT-a and PCAT-a compared to Group 2 (EAT-a: -87.6 vs. -84.0 HU, p = 0.01; PCAT-a: -90.4 vs. -83.4 HU, p &lt; 0.01). However, among patients without high plaque burden, EAT-a was increased in patients with severe OSA versus mild-moderate OSA (-80.3 vs. -84.0 HU, p = 0.020). On multivariable analysis, EAT-a independently associated with severe OSA and high plaque burden (p &lt; 0.02), and PCAT-a associated with severe OSA and high plaque burden, and hypertension (all p &lt; 0.01).

Conclusions

EAT attenuation is decreased in patients with severe OSA and high plaque burden but increased in patients with severe OSA and low plaque burden. These divergent results suggest coronary inflammation may be increased in OSA independent of CAD, but larger studies are required to validate these findings.