The relationship between sperm nuclear DNA fragmentation, mitochondrial DNA fragmentation, and copy number in normal and abnormal human ejaculates

BACKGROUND

While it is common to clinically evaluate sperm nuclear DNA fragmentation, less attention has been given to sperm mitochondrial DNA. Recently, a digital PCR assay has allowed accurate estimation of the proportion of fragmented mtDNA molecules and relative copy number.

OBJECTIVES

To determine the correlation of classical sperm parameters, average mtDNA copies per spermatozoon and the level of mtDNA fragmentation (SDF-mtDNA) to that of nuclear DNA fragmentation (SDF-nDNA), measured as the proportion of global, single-strand DNA (SDF-SSBs) and double-strand DNA breaks (SDF-DSBs). To determine whether the level of nuclear and mitochondrial DNA fragmentation and/or copy number can differentiate normozoospermic from non-normozoospermic samples.

MATERIALS AND METHODS

Ejaculates from 29 normozoospermic and 43 non-normozoospermic were evaluated. SDF was determined using the sperm chromatin dispersion assay. mtDNA copy number and SDF-mtDNA were analyzed using digital PCR assays.

RESULTS

Relative mtDNA copy increased as sperm concentration or motility decreased, or abnormal morphology increased. Unlike SDF-mtDNA, mtDNA copy number was not correlated with SDF-nDNA. SDF-mtDNA increased as the concentration or proportion of non-vital sperm increased; the higher the mtDNA copy number, the lower the level of fragmentation. Non-normozoospermic samples showed double the level of SDF-nDNA compared to normozoospermic (median 25.00 vs. 13.67). mtDNA copy number per spermatozoon was 3× higher in non-normozoospermic ejaculates (median 16.06 vs. 4.99). Although logistic regression revealed SDF-Global and mtDNA copy number as independent risk factors for non-normozoospermia, when SDF-Global and mtDNA copy number were combined, ROC curve analysis resulted in an even stronger discriminatory ability for predicting the probability of non-normozoospermia (AUC = 0.85, 95% CI 0.76-0.94, p < 0.001).

CONCLUSION

High-quality ejaculates show lower nuclear SDF and retain less mtDNA copies, with approximately half of them fragmented, so that the absolute number of non-fragmented mtDNA molecules per spermatozoon is extremely low.

Magnetically propagating Hund's exciton in van der Waals antiferromagnet NiPS3

Magnetic van der Waals (vdW) materials have opened new frontiers for realizing novel many-body phenomena. Recently NiPS3 has received intense interest since it hosts an excitonic quasiparticle whose properties appear to be intimately linked to the magnetic state of the lattice. Despite extensive studies, the electronic character, mobility, and magnetic interactions of the exciton remain unresolved. Here we address these issues by measuring NiPS3 with ultra-high energy resolution resonant inelastic x-ray scattering (RIXS). We find that Hund's exchange interactions are primarily responsible for the energy of formation of the exciton. Measuring the dispersion of the Hund's exciton reveals that it propagates in a way that is analogous to a double-magnon. We trace this unique behavior to fundamental similarities between the NiPS3 exciton hopping and spin exchange processes, underlining the unique magnetic characteristics of this novel quasiparticle.

Adjuvant Abemaciclib Plus Endocrine Therapy for Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative, High-Risk Early Breast Cancer: Results From a Preplanned monarchE Overall Survival Interim Analysis, Including 5-Year Efficacy Outcomes

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical trial updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.Two years of adjuvant abemaciclib combined with endocrine therapy (ET) resulted in a significant improvement in invasive disease-free survival (IDFS) and distant relapse-free survival (DRFS) that persisted beyond the 2-year treatment period in patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative, node-positive, high-risk early breast cancer (EBC). Here, we report 5-year efficacy results from a prespecified overall survival (OS) interim analysis. In the intent-to-treat population, with a median follow-up of 54 months, the benefit of abemaciclib was sustained with hazard ratios of 0.680 (95% CI, 0.599 to 0.772) for IDFS and 0.675 (95% CI, 0.588 to 0.774) for DRFS. This persistence of abemaciclib benefit translated to continuous separation of the curves with a deepening in 5-year absolute improvement in IDFS and DRFS rates of 7.6% and 6.7%, respectively, compared with rates of 6% and 5.3% at 4 years and 4.8% and 4.1% at 3 years. With fewer deaths in the abemaciclib plus ET arm compared with the ET-alone arm (208 v 234), statistical significance was not reached for OS. No new safety signals were observed. In conclusion, abemaciclib plus ET continued to reduce the risk of developing invasive and distant disease recurrence beyond the completion of treatment. The increasing absolute improvement at 5 years is consistent with a carryover effect and further supports the use of abemaciclib in patients with high-risk EBC.

Chinook salmon depth distributions on the continental shelf are shaped by interactions between location, season, and individual condition

BACKGROUND

Ecological and physical conditions vary with depth in aquatic ecosystems, resulting in gradients of habitat suitability. Although variation in vertical distributions among individuals provides evidence of habitat selection, it has been challenging to disentangle how processes at multiple spatio-temporal scales shape behaviour.

METHODS

We collected thousands of observations of depth from > 300 acoustically tagged adult Chinook salmon Oncorhynchus tshawytscha, spanning multiple seasons and years. We used these data to parameterize a machine-learning model to disentangle the influence of spatial, temporal, and dynamic oceanographic variables while accounting for differences in individual condition and maturation stage.

RESULTS

The top performing machine learning model used bathymetric depth ratio (i.e., individual depth relative to seafloor depth) as a response. We found that bathymetry, season, maturation stage, and spatial location most strongly influenced Chinook salmon depth. Chinook salmon bathymetric depth ratios were deepest in shallow water, during winter, and for immature individuals. We also identified non-linear interactions among covariates, resulting in spatially-varying effects of zooplankton concentration, lunar cycle, temperature and oxygen concentration.

CONCLUSIONS

Our results suggest Chinook salmon vertical habitat use is a function of ecological interactions, not physiological constraints. Temporal and spatial variation in depth distributions could be used to guide management decisions intended to reduce fishery impacts on Chinook salmon. More generally, our findings demonstrate how complex interactions among bathymetry, seasonality, location, and life history stage regulate vertical habitat selection.

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.

An evaluation of DNA sample source and molecular markers to determine gender in the short-beaked echidna (Tachyglossus aculeatus)

The short-beaked echidna is sexually monomorphic such that gender identification without veterinary intervention is challenging. The aim of this study was to evaluate and compare the most optimal noninvasive genetic source by extracting echidna genomic DNA (gDNA) from fecal scats, plucked hair, and quills to perform genetic sex testing using a range of molecular markers. Sex determination of 14 captive short-beaked echidnas was determined by amplifying isolated DNA from noninvasive samples, targeting two Y chromosome (male-specific) genes (mediator complex subunit 26 Y-gametologue [CRSPY] and anti-Müllerian hormone Y-gametologue [AMHY]), in addition to four confirmed sex-specific RADseq markers. Results of noninvasive samples were compared with blood samples and clinical records. Receiver operating characteristic curves were used to assess accuracy of sex determination of markers for each sample type. The gender of the echidnas was successfully identified on 75% of occasions using fecal samples, 90.6% occasions using hair, and 84.6% occasions with quills. Overall, the male-specific RADseq markers accurately identified the sex of echidnas with all sample types for 90% of animals; compared with 81.5% using CRSPY, and 82.0% using AMHY to identify sex. Collection of hair, quills, and feces provides a useful alternative to invasively collected samples, however, the accuracy of results depends on sample type and genetic marker selected. We found gender determination in the short-beaked echidna was most accurate using four male-specific RADseq markers on gDNA isolated from blood and hair. The noninvasive genetic sexing techniques documented here will inform and facilitate husbandry and genetic management of captive echidna populations.

Addendum to: The relationship between sperm nuclear DNA fragmentation, mitochondrial DNA fragmentation and copy number in normal and abnormal human ejaculates

BACKGROUND

While the kinetics of human sperm nuclear DNA fragmentation (SDF-nDNA) following ejaculation have been described, the dynamics and relationships of mitochondrial DNA copy number per spermatozoon (mtDNAcn) and fragmentation (SDF-mtDNA) remain unexplored.

OBJECTIVES

To compare post-ejaculatory kinetics of mtDNAcn, SDF-mtDNA and SDF-nDNA, global, single-strand DNA breaks (SDF-SSBs) and double-strand DNA breaks (SDF-DSBs) in normozoospermic and non-normozoospermic samples.

MATERIALS AND METHODS

28 normozoospermic and 43 non-normozoospermic ejaculates were evaluated at 0, 6, 24 and 48 h of incubation in vitro. SDF-nDNA was determined by sperm chromatin dispersion (SCD) assays. mtDNAcn and SDF-mtDNA were analysed by dPCR.

RESULTS

SDF-nDNA-global values increased as a consequence of quadratic SDF-SSBs and linear SDF-DSBs kinetics. Non-normozoospermic samples showed a slower SDF-global rate between 6-24 h, due to lesser SSBs production. Regarding SDF-DSBs, non-normozoospermic samples exhibited a faster initial increase rate, followed by a slower final increment. The mtDNAcn median value decreased linearly, being 3.2× higher in non-normozoospermics at all time points; mtDNAcn in both cohorts reduced to half of the baseline by 48 h. mtDNAcn was identified as a risk factor for discriminating non-normozoospermia, a finding that was further strengthen when combined with SDF-Global or SDF-DSBs values. SDF-mtDNA frequencies were identical, increasing over time correspondingly in both cohorts. The mtDNA fragmentation rate was initially fast, decreasing progressively with time for both cohorts; half of the initially unfragmented copies were fragmented after 48 h. Rates of mtDNAcn loss and SDF-mtDNA increase were only marginally correlated with the rates of nuclear fragmentation.

CONCLUSION

mtDNA fragmentation and loss occur post ejaculation. Their dynamics are likely to be associated with different and/or uncoupled mechanisms to that which cause nuclear DNA fragmentation. Our results indicate that while mtDNA fragmentation is not influenced by the sperm quality, the number of copies of sperm mtDNAcn can potentially serve as a risk factor for predicting non-normozoospermia.

The koala (Phascolarctos cinereus) prostate: a comprehensive histological and immunohistochemical investigation

The prostate of the koala (Phascolarctos cinereus), and of marsupials more generally, is the primary contributor of seminal fluid, yet comparatively little is known about its microanatomy or biochemistry. This study explored evidence of parenchymal segmentation of the koala prostate. The prostate of three sexually mature koalas were processed for histopathology, histochemistry (Masson's trichrome, Alcian Blue, periodic acid Schiff staining), and immunohistochemistry using basal (tumor protein 63, cytokeratin 14) and luminal (cytokeratin 8/18, prostate specific antigen, androgen receptor) markers. Results confirmed clear segmentation of the koala prostate into three zones, anterior, central, and posterior, characterized by differences in the proportion of glandular tissue, as well as the thickness of collagen fibers; there were also distinct differences in the secretions produced in each zone. Based on immunohistochemistry, the koala prostate showed evidence of both basal proliferative and luminal secretory cells. The ratio of cell types varied across the three segments, with the central segment housing the highest density of basal cells. Globular bodies produced in the anterior zone were shown to possess the same markers as those described for human prostasomes. This study is the first to comprehensively document the marsupial prostate in terms of microanatomy and corresponding immunohistochemistry. While further biochemical analysis, such as proteomics of each segment will better define the relative functions of each tissue, the data presented here are consistent with the hypothesis that the koala prostate potentially represents an example of an ontological stage in the evolutionary differentiation of male eutherian accessory glands.

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

PURPOSE

To identify potential predictors of response and resistance mechanisms in patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC) treated with the CDK4/6 inhibitor abemaciclib +/- endocrine therapy (ET), baseline and acquired genomic alterations in circulating tumor DNA (ctDNA) were analyzed and associated with clinical outcomes.

PATIENTS AND METHODS

MONARCH 3: postmenopausal women with HR+, HER2- ABC and no prior systemic therapy in the advanced setting were randomized to abemaciclib or placebo plus nonsteroidal aromatase inhibitor (NSAI). nextMONARCH: women with HR+, HER2- metastatic breast cancer that progressed on/after prior ET and chemotherapy were randomized to abemaciclib alone (two doses) or plus tamoxifen. Baseline and end-of-treatment plasma samples from patients in MONARCH 3 and nextMONARCH (monotherapy arms) were analyzed to identify somatic genomic alterations. Association between genomic alterations and median progression-free survival (mPFS) was assessed.

RESULTS

Most patients had ≥1 genomic alteration detected in baseline ctDNA. In MONARCH 3, abemaciclib+NSAI was associated with improved mPFS versus placebo+NSAI, regardless of baseline alterations. ESR1 alterations were less frequently acquired in the abemaciclib+NSAI arm than placebo+NSAI. Acquired alterations potentially associated with resistance to abemaciclib +/- NSAI included RB1 and MYC.

CONCLUSIONS

In MONARCH 3, certain baseline ctDNA genomic alterations were prognostic for ET but not predictive of abemaciclib response. Further studies are warranted to assess whether ctDNA alterations acquired during abemaciclib treatment differ from other CDK4/6 inhibitors. Findings are hypothesis-generating, further exploration is warranted into mechanisms of resistance to abemaciclib and ET.

Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors: existing and emerging differences

The cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors palbociclib, ribociclib, and abemaciclib are standard-of-care therapy for hormone receptor-positive advanced or metastatic breast cancer, based on randomized trials showing improved progression-free survival for all 3 drugs and overall survival for ribociclib and abemaciclib. Results in early breast cancer are discordant, with sustained improvement in invasive disease-free survival demonstrated for abemaciclib but not other CDK4/6 inhibitors to date. We review nonclinical studies exploring mechanistic differences between the drugs, the impact of continuous dosing on treatment effect, and translational research into potential resistance mechanisms and prognostic and predictive markers. We focus particularly on how emerging findings may help us understand similarities and differences between the available CDK4/6 inhibitors. Even at late-stage clinical development, there remains much to learn about how agents in this class exert their varying effects.

Resonant inelastic x-ray scattering data for Ruddlesden-Popper and reduced Ruddlesden-Popper nickelates

Ruddlesden-Popper and reduced Ruddlesden-Popper nickelates are intriguing candidates for mimicking the properties of high-temperature superconducting cuprates. The degree of similarity between these nickelates and cuprates has been the subject of considerable debate. Resonant inelastic x-ray scattering (RIXS) has played an important role in exploring their electronic and magnetic excitations, but these efforts have been stymied by inconsistencies between different samples and the lack of publicly available data for detailed comparison. To address this issue, we present open RIXS data on La₄Ni₃O₁₀ and La₄Ni₃O₈.

Abstract PD10-08: PD10-08 Immune cell infiltration associated with poor anti-proliferative response to aromatase inhibitors in postmenopausal women with primary ER-positive HER2-negative breast cancer

Background: Aromatase inhibitors (AIs) are one of the main treatment strategies for the clinical management of estrogen receptor-positive (ER+) breast cancer (BC). Despite prolonged time to recurrence and initial clinical responses, &gt;20% of patients eventually relapse, and previous studies have shown an association of poor anti-proliferative response to AIs and worse outcome. High immune activity in ER+ tumors may be associated with worse outcome, in contrast to ER-negative BC where immune infiltration is a feature associated with better outcome. Our work focused on understanding the correlations between immune cell infiltration and response to AI. Methods: All patients with ER+ HER2- tumors within the bottom 15% of Ki67 anti-proliferative responders to AIs (poor responders [PRs]; n=177) were selected from the PeriOperative Endocrine Therapy for Individualizing Care (POETIC) trial and matched on baseline Ki67 levels to good responders (GRs) within the 50% showing the best response (n=190). Response to AI was measured by the Ki67 percentage change after 2 weeks of treatment. PRs were further divided into groups expressing high ESR1 (PRs ESR1HIGH; n=119) and low ESR1 (PRs ESR1LOW; n=58) levels to represent PR subgroups that showed partial or no response to AIs. The percentage of stromal tumor-infiltrating lymphocytes (TILs) was assessed. Multiple immunofluorescence was performed for ER, CD3, CD20, CD68, FOXP3, and CD3/FOXP3 in 15 baseline samples from each of the GR, PR ESR1HIGH, and PR ESR1LOW populations and immune cell density in stromal or tumor compartments was estimated. Spearman correlations of TILs with Consensus tumor microenvironment (TME) deconvolution and Molecular Signatures Database hallmark gene sets were conducted. The relationship between the immune markers’ density and genes, hallmark gene sets and Consensus TME was assessed. Results: The percentage of TILs was significantly higher in the PR ESR1HIGH and PR ESR1LOW compared to the GRs (adjusted p&lt; 0.05). As expected, TILs were highly correlated with T cells (particularly T-regulatory cells) and immune hallmark gene sets. There was a tendency for higher density of each of the immune markers in PRs compared to GRs, with significant differences being observed in stromal B-cell marker CD20 density (p&lt; 0.05). Analysis showed a significant correlation between TILs and stromal FOXP3 marker density (FDR&lt; 0.05), and stromal biomarker density was highly correlated to the gene expression of the encoding genes of the same tumors (CD3/CD3D, FOXP3/FOXP3, and CD20/MS4A1) (FDRs&lt; 0.05). There was also a strong and significant correlation between the stromal expression of CD20, CD3, FOXP3, and CD3/FOXP3 with the immune hallmark gene sets (FDRs&lt; 0.05). Finally, the immune phenotyping showed the expected correlations with TME deconvolution, with particularly strong correlations of CD20 and CD3 with B- and T-cell gene signatures, respectively (FDRs&lt; 0.05). Conclusions: Different immune features indicated a broad involvement of several immune cell types in PRs to AIs, suggesting that the immune system might be associated with resistance of ER+ breast tumors to AI treatment. Spatial gene expression profiling is ongoing to characterize these tumors further and investigate potential mechanisms of AI resistance.

Citation Format: Anastasia Alataki, Gene Schuster, Lila Zabaglo, Perry Maxwell, Elena López-Knowles, Elizabeth Folkerd, David Evans, Kally Sidhu, Holly Tovey, Nicholas Turner, Stephen Johnston, Maggie Chon U Cheang, John Robertson, Manuel Salto-Tellez, Ian Smith, Judith Bliss, Mitch Dowsett. PD10-08 Immune cell infiltration associated with poor anti-proliferative response to aromatase inhibitors in postmenopausal women with primary ER-positive HER2-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 PD10-08.

Abstract MS1-3: Treatment of ER+/HER2+ breast cancer

Co-expression of hormone receptors (HR) and human epidermal growth factor receptor 2 (HER2) occurs in 10% of all breast cancers, and due to cross-talk mechanisms that influence cell signalling the co-expression of these receptors modulates response of these cancers to both HER2-directed and endocrine therapies. Prior to the advent of HER2 targeted therapies, patients with HR+/HER2+ breast cancer had a significantly worse prognosis compared with HR+/HER2- breast tumours, primarily related to HER2 signalling driving endocrine resistance. Likewise, prior clinical studies in the neoadjuvant setting showed that patients with HR+/HER2+ primary breast cancer had a lower pathological complete response rate to HER2-targeted therapy plus chemotherapy that those with HR-/HER2+ tumours, suggesting a different biology. As such, strategies that combine receptor blockade against HER2 and HR have been developed in metastatic breast cancer (MBC), confirming that combined blockade is better than endocrine therapy (ET) alone, and then that dual HER2 blockade + ET was superior to single HER2 therapy + ET. More recently combinations of a CDK 4/6 inhibitor with ET and HER2 therapy has shown significant clinical efficacy and survival benefit in heavily pre-treated patients, confirming the efficacy for non-chemotherapy targeted combinations in HR+/HER2+ MBC. In the early breast cancer (EBC) setting, most HER2 directed therapy is given in combination with chemotherapy in the neoadjuvant setting, while studies of combined ET and HER2 targeted strategies without chemotherapy work slower with lower pCR rates. As such, the real benefit for combined targeted therapy may be in the adjuvant setting where ET and HER2 therapy are routinely given together following completion of chemotherapy. Furthermore, extended adjuvant ET/HER2 therapy beyond completion of antibody based treatment may also provide extra benefit, and in higher risk patients longer treatment may prove an important consideration.

Citation Format: Stephen Johnston. Treatment of ER+/HER2+ 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 MS1-3.

Abstract GS1-09: Abemaciclib plus endocrine therapy for HR+, HER2-, node-positive, high-risk early breast cancer: results from a pre-planned monarchE overall survival interim analysis, including 4-year efficacy outcomes

Background Adjuvant abemaciclib (a CDK4 and 6 inhibitor) combined with ET resulted in significant and clinically meaningful improvement in invasive disease-free survival (IDFS) and distant relapse-free survival (DRFS) in patients (pts) with HR+, HER2-, node-positive, high risk EBC in the monarchE trial, and is an approved adjuvant therapy for these patients. Here we present efficacy results from a pre-specified overall survival interim analysis (OS IA2) which was planned to occur 2 years (yrs) after the primary outcome analysis. Methods Pts were randomized (1:1) to receive ET for up to 10 yrs +/- abemaciclib for 2 yrs (study treatment period). High-risk EBC was defined as either ≥4 positive axillary lymph nodes (ALN), or 1-3 ALN with either Grade 3 disease and/or tumor ≥5 cm (Cohort 1). While the proliferation biomarker Ki-67 was centrally assessed in all pts with available tissue sample, an additional smaller group of pts with 1-3+ ALN and central Ki-67 ≥20% as the only high-risk feature were included (Cohort 2). The intent-to-treat (ITT) population consisted of both Cohort 1 (5120 pts) and Cohort 2 (517 pts). Hazard ratios (HR) were estimated using Cox proportional hazard model. Results At a median follow-up of 42 months, all pts were off abemaciclib. IDFS and DRFS data illustrate a sustained benefit beyond the treatment period. In the ITT population, the HR for IDFS was 0.664 (95% CI: 0.578, 0.762) and DRFS was 0.659 (95% CI: 0.567, 0.767). At 4 yrs, this reflected an improvement in IDFS rates from 79.4% to 85.8% (absolute difference 6.4%), and in DRFS rates from 82.5% to 88.4% (absolute difference 5.9%). The continued separation of the curves was associated with an increase in absolute benefit in IDFS 4-year rates compared to 2-and 3-year IDFS rates (absolute difference 2.8% and 4.8% respectively). While OS remained immature, there was a lower number of deaths observed in the abemaciclib plus ET arm compared to the ET alone arm (157 [5.6%] vs 173 [6.1%], HR 0.929 [95% CI: 0.748, 1.153], p = 0.503), suggesting that the robust benefit in IDFS and DRFS began to translate into a numerically favorable OS HR. As previously described, within Cohort 1, a Ki-67 index of ≥20% was associated with a worse prognosis, but similar abemaciclib treatment effects were observed regardless of Ki-67 index. No new safety signals were observed. Conclusion The clinically meaningful benefit of adjuvant abemaciclib added to ET in HR+, HER2-, node-positive, high-risk EBC persists beyond completion of abemaciclib therapy, yielding an increase in absolute IDFS and DRFS benefit at 4 yrs. While OS remains immature at this time, the lower number of deaths in the abemaciclib arm compared to the ET arm suggest that a survival signal favoring abemaciclib is emerging.

Citation Format: Stephen Johnston, Masakazu Toi, Joyce O’Shaughnessy, Priya Rastogi, Mario Campone, Patrick Neven, Chiun Sheng Huang, Jens Huober, Georgina Garnica Jaliffe, Irfan Cicin, Sara Tolaney, Matthew P. Goetz, Hope Rugo, Elżbieta Senkus, Laura Testa, Lucia Del Mastro, Chikako Shimizu, Ran Wei, Ashwin Shahir, Maria Munoz, Belen San Antonio, Valerie Andre, Nadia Harbeck, Miguel Martín. Abemaciclib plus endocrine therapy for HR+, HER2-, node-positive, high-risk early breast cancer: results from a pre-planned monarchE overall survival interim analysis, including 4-year efficacy outcomes [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS1-09.

Abstract P5-05-01: Personalized Cancer Monitoring (PCM): a novel ctDNA tool to detect molecular residual disease in patients with early-stage breast cancer

Introduction: Identification of Molecular Residual Disease (MRD) in patients with breast cancer with circulating tumor DNA (ctDNA) presents a strategy to identify patients at high risk of relapse. Approaches that detect ctDNA at lower concentrations are required to increase sensitivity and improve on the lead time between ctDNA detection and clinical relapse. Here we present results using novel highly sensitive tumor-informed sequencing assays for ctDNA detection of MRD based on detection of multiple patient specific mutations in ctDNA. Methods: 62 stage II-III breast cancer patients (23 hormone receptor positive HER2 negative (HR+HER2-), 20 HER2+, 15 triple negative breast cancer (TNBC) and 4 unknown receptor status) enrolled in the ChemoNEAR sample collection study were included. All patients received neoadjuvant chemotherapy, followed up by surgery, with samples taken at diagnosis, and post-surgery every 3 months for the first two years, followed by every 6 months for up to five years. Tumor DNA from FFPE samples and germline was Whole Exome Sequenced to identify patient specific mutations and design anchored-multiplex PCR (AMP™) Personalized Cancer Monitoring (PCMTM) assays to track mutations in plasma. Cell free DNA was extracted from 613 plasma samples (median volume 4ml, range 0.5-4.5ml) and sequenced with PCMTM assays, with 37-177 variants (median 52) per panel, to a depth of 100,000x per locus. A proprietary algorithm was used to identify ctDNA. Results: At a median follow-up of 52.7 months post-surgery (range 15.3-96.4 months), ctDNA was detected in 25.8% (16/62) of patients, with detected ctDNA levels ranging from allele frequency (AF) of 0.01%, to 32.5%) (median 0.24% AF). Detection of ctDNA was associated with a high risk of future relapse (HR 65.4, 95% CI 14.5-293.7), with a median lead-time from ctDNA detection to clinical relapse of 13.7 months (range 3.9-58.9). MRD was identified in 76.9% (10/13) of patients who relapsed. ctDNA was detected prior to relapse in both patients with brain only relapse, but with a reduced lead time over clinical relapse (5.73 and 3.90 months), which was previously not achievable with digital PCR MRD-detection assays. Of patients with assessable baseline samples, 81% (39/48) had ctDNA detected. No patients with undetected ctDNA, or detectable ctDNA with AF&lt; 0.1%, relapsed during follow-up, whereas ctDNA was detected at baseline in all 10 patients who relapsed during follow-up (p=0.1). Conclusions: PCMTM detected breast cancer relapse with a long lead-time over clinical relapse, and strong association with relapse free survival, an advancement over previously published data with digital PCR MRD detection. Prospective, interventional trials are now required to assess whether treatment on the basis of MRD detection improves outcome, including the TRAK ER Trial (NCT04985266).

Citation Format: Isaac Garcia-Murillas, Giselle Walsh-Crestani, Edward Phillips, Rosalind Cutts, Sarah Hrebien, Kathryn Dunne, Kally Sidhu, Robert Daber, Amber C. Carter, Lorena De La Peña, Stephen Johnston, Alistair Ring, Simon Russell, Abigail Evans, Anthony Skene, Duncan Wheatley, Ian Smith, Nicholas Turner. Personalized Cancer Monitoring (PCM): a novel ctDNA tool to detect molecular residual disease in patients with early-stage 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 P5-05-01.

Abstract PD10-07: PD10-07 Low plasma estradiol, low expression of estrogen responsive genes and TP53 mutations are associated with poor anti-proliferative response to aromatase inhibitors

Background: Aromatase inhibitors (AIs) are highly effective at reducing recurrences and mortality in postmenopausal patients with estrogen receptor positive breast cancer (ER+ BC). Poor anti-proliferative (Ki67) response or ER+ BCs to AIs after 2 weeks is associated with worse long-term outcomes. Factors that relate to the degree of the response may identify markers and/or mechansims of resistance. Methods: The PeriOperative Endocrine Therapy for Individualizing Care (POETIC) trial randomized 4,480 with ER+ BC to 2 weeks’ AI before surgery or no presurgical treatment. All patients within the bottom 15% of Ki67 responders to AI (poor responders [PRs]; n=177 with RNA extracted) were selected from and matched to good responders (GRs) within the 50% showing the best response (n=190). Matching was based on baseline Ki67 levels as measured by immunohistochemistry (IHC). Response to AI was measured by the percentage change in Ki67 after 2 weeks’ treatment. PRs were further divided into groups expressing high ESR1 (PRs ESR1HIGH; n=119) and low ESR1 (PRs ESR1LOW; n=58) levels since there were very few GRs with low ESR1. RNAseq, targeted exome DNA sequencing of 87 BC/resistance related genes and measurement of plasma estradiol levels by mass spectrometry were performed to understand mechanisms of de novo resistance. Intrinsic subtypes were estimated from RNAseq data. Results: More than 90% of PRs ESR1LOW were non-luminal subtypes with low expression of estrogen-responsive genes. In contrast, 11% of PRs ESR1HIGH were non-luminal compared to 4% of GRs but only HER2-enriched subtypes were significantly higher in PR ESR1HIGH (p=0.05, Fisher exact). While AI treatment had limited impact on Ki67 IHC values in PRs ESR1HIGH, PGR expression was more than 2-fold lower after 2 weeks of AI. Gene-set enrichment analysis showed significantly lower expression of estrogen-response genes in PRs ESR1HIGH compared to GRs (FDR&lt; 10-9) at baseline despite similar percentage of Luminal subtypes in PRs ESR1HIGH and GRs. Plasma estradiol levels were correlated with expression of estrogen-response genes (FDR=0.01) and levels were significantly lower in PRs ESR1HIGH compared to GRs (p=0.003, Mann Whitney). PRs ESR1HIGH had significantly more mutations in RB1, TP53, ARID1B and DNAH11 genes (p&lt; 0.05, Fisher exact). TP53 mutations were significantly enriched in Luminal-A PRs ESR1HIGH compared to GRs (22% and 3% respectively; p=0.003, Fisher exact), but not in Luminal-B tumors (23% and 15% mutated respectively). Discussion and conclusions: In approximately 33% of PRs, de novo AI resistance was associated with and most likely due to low expression of ER/ESR1 and estrogen-responsive genes in non-luminal tumors. In the remaining tumors, AI treatment still impacted some estrogen responsive genes but had limited downstream impact on suppressing proliferation. This might be due to mutations including in TP53 that limit suppression of proliferation downstream of estrogen signaling. The proportion of Luminal tumors in GRs and PRs ESR1HIGH was similar, suggesting better outcome of Luminal-A tumors on AI is likely due to their better intrinsic prognosis rather than better response to endocrine therapy.

Citation Format: Eugene F. Schuster, Elena López-Knowles, Anastasia Alataki, Lila Zabaglo, Elizabeth Folkerd, David Evans, Kally Sidhu, Holly Tovey, Perry Maxwell, Nicholas Turner, Stephen Johnston, Manuel Salto-Tellez, Maggie Chon U Cheang, John Robertson, Ian Smith, Judith Bliss, Mitch Dowsett. PD10-07 Low plasma estradiol, low expression of estrogen responsive genes and TP53 mutations are associated with poor anti-proliferative response to aromatase inhibitors [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 PD10-07.

The efficacy of novel centrifugation-free sperm selection (Io-Lix) on sperm parameters and ICSI reproductive outcomes

RESEARCH QUESTION

What is the effect of a novel non-centrifugation method (Io-Lix) of sperm selection on sperm parameters and intracytoplasmic sperm injection (ICSI) reproductive outcomes?

DESIGN

This pilot study elevated the capacity of the Io-Lix sperm selection protocol to improve sperm parameters (concentration, motility and sperm DNA fragmentation) of the neat ejaculate. Once established, the reproductive outcomes of Io-Lix selected spermatozoa were used for autologous and donor oocyte ICSI programmes and their efficacy compared with those using conventional swim-up.

RESULTS

Io-Lix sperm selection resulted in lower sperm concentration yield (P < 0.001) and sperm DNA fragmentation (P < 0.001) but higher sperm motility (P < 0.001) when compared with spermatozoa in the neat ejaculate. When compared with swim-up sperm selection the Io-Lix protocol resulted in a 14.7% (P = 0.028) increase in pregnancy rate and 16.3% (P = 0.047) reduction in miscarriages in the autologous ICSI programme. A similar comparison of sperm selection procedures employed for a donor oocyte ICSI programme showed no difference in terms of their respective reproductive outcomes.

CONCLUSIONS

The Io-Lix sperm selection protocol resulted in improved pregnancy rate and reduction in miscarriage when applied to autologous ICSI, which was attributed to a reduction in the proportion of spermatozoa with DNA damage post-selection. A similar finding was not apparent in the donor oocyte programme, which may be associated with the capacity of the donor oocyte to repair sperm DNA post-syngamy.

Bacterial DNase activity as a putative inductor of sperm DNA fragmentation in infected bull frozen-thawed semen samples

The aim of this study was to investigate the relationship between DNase activity associated with bacterial contamination of incubated bovine frozen-thawed spermatozoa and elevated sperm DNA fragmentation. Electrophoresis analysis of plasmid PBR322 incubated for 30 min at 37 °C with the supernatant of the diluent of frozen-thawed centrifuged bovine semen straws infected with bacteria showed clear evidence of DNase activity when compared to plasmid incubated in similarly prepared non-infected bovine diluent supernatant (Experiment 1). This DNase activity was subsequently found to be time dependent (0-60 min) and its activity prevented in the presence of EDTA (10 and 20 mM; Experiment 2). Semen straws infected (n = 10) and not infected (n = 10) with bacteria where incubated at 37 °C for up to 48h post-thaw. Semen infected with bacteria showed an exponential increase in bacterial growth and a corresponding increase in sperm DNA fragmentation. Non-infected semen samples showed no change in the incidence of sperm DNA fragmentation over the same period of incubation (Experiment 3). Our experiments reinforce the idea that exogenous DNases present in the semen should be considered as one of the primary contributing causes of sperm DNA fragmentation post ejaculation. In the case of the bull, post-thaw incubation of commercial straws contaminated with bacteria, resulted in increased levels of sperm DNA fragmentation, most likely associated with DNase activity (potentially restriction endonucleases) derived from the bacteria. Such adverse changes in sperm DNA fragmentation, as described here in vitro, may be also operative after insemination in the female reproductive tract (in vivo) and highlight the importance of implementing high levels of hygiene practice during semen processing, especially in light of future trends of bacterial resistance to the common antibiotics used in semen diluents.

Comparison of Clinical Outcomes of Gripping Surface Technology Staple Reloads versus Standard Staple Reloads Used with Manual Linear Surgical Staplers

PURPOSE

Linear surgical staplers reduce rates of surgical adverse events (bleeding, leaks, infections) compared to manual sutures thereby reducing patient risks, surgeon workflow disruption, and healthcare costs. However, further improvements are needed. Ethicon Gripping Surface Technology (GST) reloads, tested and approved by regulatory authorities in combination with powered staplers, may reduce surgical risks through improved tissue grip. While manual staplers are used in some regions due to affordability, clinical data on GST reloads used with manual staplers are unavailable. This study compared surgical adverse event rates of manual staplers with GST vs standard reloads. These data may be used for label changes in China and Latin America.

PATIENTS AND METHODS

Patients undergoing general or thoracic surgery between October 1, 2015 and August 31, 2021 using ECHELON FLEX™ manual staplers with GST or standard reloads were identified from the Premier Healthcare Database. GST reloads were compared to standard reloads for non-inferiority in bleeding and anastomotic leak for general surgery. Secondary outcomes included sepsis for general surgery, and bleeding and prolonged air leak for thoracic surgery. Covariate balancing was performed using stable balancing weights.

RESULTS

The general and thoracic surgery cohorts contained 4571 (GST: 2780; standard: 1791) and 814 (GST: 514; standard: 300) patients, respectively. GST reloads were non-inferior to standard reloads for bleeding and anastomotic leak (adjusted cumulative incidence ratio: 1.02 [90% CI: 0.71, 1.45] and 1.03 [90% CI: 0.72, 1.46], respectively) for general surgery. Compared with standard reloads, GST reloads had a similar incidence of sepsis (2.2% vs 2.1%) for general surgery and lower incidences of bleeding (9.5% vs 16.0%) and prolonged air leak (12.6% vs 14.0%,) for thoracic surgery.

CONCLUSION

GST reloads, compared to standard reloads, used with ECHELON FLEX™ manual staplers had comparable perioperative bleeding and anastomotic leak for general surgery, and lower incidences of safety events for thoracic surgery.

Indirect Treatment Comparison of Daratumumab, Pomalidomide, and Dexamethasone Versus Standard of Care in Patients with Difficult-to-Treat Relapsed/Refractory Multiple Myeloma

INTRODUCTION

The phase 3 APOLLO study demonstrated significantly better progression-free survival (PFS) and clinical responses with daratumumab, pomalidomide, and dexamethasone (D-Pd) versus pomalidomide and dexamethasone (Pd) in patients with relapsed/refractory multiple myeloma (RRMM). On the basis of these results and those from the phase 1b EQUULEUS trial, D-Pd was approved in this patient population. In the absence of head-to-head data comparing D-Pd with further standard of care (SOC) therapies, indirect treatment comparisons (ITCs) can provide important information to help optimize treatment selection. The objective of this study was to indirectly compare PFS improvement with D-Pd versus daratumumab, bortezomib, and dexamethasone (D-Vd) and D-Pd versus bortezomib and dexamethasone (Vd) in patients with RRMM.

METHODS

Patient-level data were from APOLLO, EQUULEUS, and CASTOR. Three methods of adjusting imbalances in baseline characteristics including stabilized inverse probability of treatment weighting (sIPTW), cardinality matching (CM), and propensity score matching (PSM) were initially considered. CM offers mathematically guaranteed largest matched sample meeting pre-specified maximum standardized mean difference criteria for matching covariates. sIPTW and PSM were based on propensity scores derived from logistic regression. Feasibility assessment of the PSM method returned too low effective sample size to support a meaningful comparison. CM was chosen as the base case and sIPTW as a sensitivity analysis.

RESULTS

After harmonized eligibility criteria were applied, 253, 104, and 122 patients from the D-Pd, D-Vd, and Vd cohorts, respectively, were included in the ITC analyses. Some imbalances in baseline characteristics were identified between D-Pd and D-Vd/Vd cohorts that remained after adjustment. PFS hazard ratios showed significant improvement for D-Pd over D-Vd and Vd for CM and sIPTW analyses.

CONCLUSIONS

Results showed consistent PFS benefit for D-Pd versus D-Vd and Vd regardless of the adjustment technique used. These findings support the use of D-Pd versus D-Vd or Vd in patients with difficult-to-treat RRMM.

TRIAL REGISTRATION

NCT03180736; NCT02136134, NCT01998971.

Neratinib in advanced HER2-positive breast cancer: experience from the royal Marsden hospital

PURPOSE

To describe the tolerability and efficacy of neratinib as a monotherapy and in combination with capecitabine in advanced HER2-positive breast cancer in a real-world setting.

METHODS

Patients who received neratinib for advanced HER2-positive at the Royal Marsden Hospital NHS Trust between August 2016 and May 2020 were identified from electronic patient records and baseline characteristics, previous treatment and response to treatment were recorded. The primary endpoint of the study was progression-free survival (PFS). Secondary endpoints included overall survival (OS) and safety.

RESULTS

Seventy-two patients were eligible for the analysis. Forty-five patients received neratinib in combination with capecitabine and 27 patients received monotherapy. After a median duration of follow-up of 38.5 months, the median PFS for all patients was 5.9 months (95% confidence interval (CI) 4.9-7.4 months) and median OS was 15.0 months (95% Cl 10.4-22.2 months). Amongst the 52.7% (38/72) patients with confirmed brain metastases at baseline, median PFS was 5.7 months (95% CI 2.9-7.4 months) and median OS was 12.5 months (95% CI 7.7-21.4 months). Despite anti-diarrhoeal prophylaxis, diarrhoea was the most frequent adverse event, reported in 64% of patients which was grade 3 in 10%. There were no grade 4 or 5 toxicities. Seven patients discontinued neratinib due to toxicity.

CONCLUSIONS

Neratinib monotherapy or in combination with capecitabine is a useful treatment for patients with and without brain metastases. PFS and OS were found to be similar as previous trial data. Routine anti-diarrhoeal prophylaxis allows this combination to be safely delivered to patients in a real-world setting.

Precision Determination of the Neutral Weak Form Factor of ^{48}Ca

We report a precise measurement of the parity-violating (PV) asymmetry A_{PV} in the elastic scattering of longitudinally polarized electrons from ^{48}Ca. We measure A_{PV}=2668±106(stat)±40(syst) parts per billion, leading to an extraction of the neutral weak form factor F_{W}(q=0.8733  fm^{-1})=0.1304±0.0052(stat)±0.0020(syst) and the charge minus the weak form factor F_{ch}-F_{W}=0.0277±0.0055. The resulting neutron skin thickness R_{n}-R_{p}=0.121±0.026(exp)±0.024(model)  fm is relatively thin yet consistent with many model calculations. The combined CREX and PREX results will have implications for future energy density functional calculations and on the density dependence of the symmetry energy of nuclear matter.

Sperm DNA damage in men with spinal cord injury: the relative incidence of single- and double-strand DNA breaks

BACKGROUND

Men with spinal cord injury (SCI) show a high proportion of sperm DNA damage in their ejaculate but the underlying pathology remains elusive.

OBJECTIVE

To investigate the relative incidence of single (SSBs) and double-strand DNA breaks (DSBs) and DNase activity in men with SCI.

MATERIALS AND METHODS

This study included ejaculates of 20 men with SCI and 27 normozoospermic (sperm donors). A TwoTails comet assay (TTComet) allowed visualization of three categories of sperm DNA damage corresponding to SSBs, DSBs and those with a combination of SSBs and DSBs, facilitating accurate calculation of the total proportion of SSBs and DSBs. A subset of 15 individuals (sperm donors and SCI patients) was used to test for DNase activity in the seminal plasma.

RESULTS

While the proportion of DSBs in men with SCI (median-57.5%) was higher (P = 0.000) than normozoospermic samples (median-4.6%), the proportion of SSBs was higher (P = 0.022) in the normozoospermic ejaculates (median-6.0%) compared to men with SCI (median-2.5%). The relative proportion of the total DSBs with respect to the total SSBs was 3.3× in men with SCI but 0.9× in normozoospermic samples. We further confirmed the high DNase activity in the seminal plasma of men with SCI.

DISCUSSION

The TTComet assay provided new insights to the pathology of sperm DNA in men with SCI and may have diagnostic value in developing sperm selection methodologies to reduce DSBs prior to ART.

CONCLUSION

Men with SCI are characterized by a high proportion of sperm with DSBs and high levels of DNase activity in the seminal plasma compared to normozoospermic men.

A look at current and potential treatment approaches for hormone receptor-positive, HER2-negative early breast cancer

The heterogeneity of hormone receptor (HR)-positive, HER2-negative early breast cancers reinforces the importance of individualized, risk-adapted treatment approaches. Numerous factors contribute to the risk for recurrence, including clinical tumor features, individual biomarkers, and genomic risk. Current standard approaches for patients with HR-positive, HER2-negative, early stage disease focus on endocrine therapy and chemotherapy. The specific treatment regimen and duration of adjuvant therapy should be selected based on accurate risk assessment, tolerability of available therapies, and consideration for patient preferences. For patients with high-risk features, such as highly proliferative tumors, large tumor size, and significant nodal involvement, the risk for recurrence remains clinically significant despite appropriate adjuvant treatment with current standards of care. This has driven investigation into novel treatment approaches, including the addition of cyclin-dependent kinase 4 and 6 inhibitors to adjuvant endocrine therapy. Cyclin-dependent kinase 4 and 6 inhibition has demonstrated significant efficacy in patients with high-risk, HR-positive, HER2-negative, nonmetastatic breast cancer and now offers a new strategy to greatly improve outcomes in this difficult to treat patient population.; LAY SUMMARY: Hormone receptor (HR)-positive, HER2-negative early breast cancers are highly diverse and need to be managed differently for individual patients. The use of adjuvant endocrine therapy and chemotherapy should be driven by a patient's risk for recurrence, preferences, and risk for side effects. Patients with high-risk tumors have a persistently elevated risk for recurrence despite current standards of care. Emerging cyclin-dependent kinase 4 and 6 inhibitors are highly effective when added to endocrine therapy in high-risk, HR-positive early breast cancer and have the potential to improve patient outcomes in this difficult to treat patient population.

New Measurements of the Beam-Normal Single Spin Asymmetry in Elastic Electron Scattering over a Range of Spin-0 Nuclei

We report precision determinations of the beam-normal single spin asymmetries (A_{n}) in the elastic scattering of 0.95 and 2.18 GeV electrons off ^{12}C, ^{40}Ca, ^{48}Ca, and ^{208}Pb at very forward angles where the most detailed theoretical calculations have been performed. The first measurements of A_{n} for ^{40}Ca and ^{48}Ca are found to be similar to that of ^{12}C, consistent with expectations and thus demonstrating the validity of theoretical calculations for nuclei with Z≤20. We also report A_{n} for ^{208}Pb at two new momentum transfers (Q^{2}) extending the previous measurement. Our new data confirm the surprising result previously reported, with all three data points showing significant disagreement with the results from the Z≤20 nuclei. These data confirm our basic understanding of the underlying dynamics that govern A_{n} for nuclei containing ≲50 nucleons, but point to the need for further investigation to understand the unusual A_{n} behavior discovered for scattering off ^{208}Pb.

Adjuvant Abemaciclib Combined with Endocrine Therapy for High Risk Early Breast Cancer: Safety and Patient-Reported Outcomes From the monarchE Study

BACKGROUND

In monarchE, abemaciclib plus endocrine therapy (ET) as adjuvant treatment of hormone receptor-positive, human epidermal growth factor 2-negative, high risk, early breast cancer demonstrated a clinically meaningful improvement in invasive disease-free survival versus ET alone. Detailed safety analyses conducted at a median follow-up of 27 months and key patient-reported outcomes (PRO) are presented.

PATIENTS AND METHODS

The safety population included all patients who received at least one dose of study treatment (n=5591). Safety analyses included incidence, management, and outcomes of common and clinically relevant adverse events (AEs). Patient-reported health-related quality-of-life, ET symptoms, fatigue, and side effect burden were assessed.

RESULTS

The addition of abemaciclib to ET resulted in higher incidence of Grade≥3 AEs (49.7% vs 16.3% with ET alone), predominantly laboratory cytopenias (e.g., neutropenia [19.6%]) without clinical complications. Abemaciclib-treated patients experienced more serious adverse events (SAEs; 13.3% vs 7.8%). Discontinuation of abemaciclib and/or ET due to AEs occurred in 18.5% of patients, mainly due to Grade1/2 AEs (66.8%). AEs were managed with comedications (e.g., antidiarrheals), abemaciclib dose holds (61.7%), and/or dose reductions (43.4%). Diarrhea was generally low grade (Grade1/2: 77%); Grade2/3 events were highest in the first month (20.5%), most short-lived (≤7 days) and did not recur. Venous thromboembolic events (VTE) were higher with abemaciclib+ET (2.5%) vs ET (0.6%); in the abemaciclib arm, increased VTE risk was observed with tamoxifen vs AIs (4.3% vs 1.8%). PROs were similar between arms, including being 'bothered by side effects of treatment', except for diarrhea. At ≥3 months, most patients reporting diarrhea reported "a little bit" or "somewhat".

CONCLUSION

In patients with high risk EBC, adjuvant abemaciclib+ET has an acceptable safety profile and tolerability is supported by PRO findings. Most AEs were reversible and manageable with comedications and/or dose modifications, consistent with the known abemaciclib toxicity profile.

Abstract P1-17-03: H3B-6545 in combination with palbociclib in women with metastatic estrogen receptor-positive (ER+), human epidermal growth factor receptor 2 (HER2)-negative breast cancer, phase 1b study

Background: H3B-6545, a novel Selective ERα Covalent Antagonist (SERCA), inactivates both mutant and wild-type ERα by targeting cysteine 530 and enforcing antagonist conformation. It demonstrated a manageable safety profile and single-agent antitumor activity in heavily pretreated ER+, HER2- mBC patients (pts) (Hamilton et al, ASCO, 2021). Methods: The study aims at determining the recommended phase II doses of the combination of H3B-6545 and palbociclib in pts with ER+, HER2- mBC. Other endpoints include safety, pharmacokinetics, and preliminary efficacy. The escalation phase enrolls pts with at least 2 prior therapies in the metastatic setting. Up to one prior chemotherapy and up to one prior CDK4/6 inhibitor are allowed. Each cohort enrolled 6 pts to ensure availability of sufficient PK data. During the first cycle, H3B-6545 was added to palbociclib on day 9. Dose-limiting toxicities (DLTs) were assessed during the first 28 days starting from the 1st day of adding H3B-6545 to palbociclib (cycle 1 day 9 to cycle 2 day 8). Both drugs were started on day 1 of each of the subsequent cycles. Results: As of June 15, 2021, 14 pts were enrolled: 7 in Cohort 1 (H3B-6545 300 mg QD and palbociclib 100 mg QD) and 7 in Cohort 2 (H3B-6545 300 mg QD and palbociclib 125 mg QD). Median age was 61 years (range: 28-75 years), ECOG performance status was 0 in 7 pts (50%) and 1 in 7 pts (50%) and 9 pts (64%) had lung and/or liver metastases. Median number of prior therapies in the metastatic setting was 3 (range: 1-6). Prior therapy in the metastatic setting included fulvestrant (93%), CDK4/6 inhibitors (79%), aromatase inhibitors (64%), and chemotherapy (29%). One pt in each Cohort was not evaluable for dose limiting toxicity (DLT) assessment and no DLTs were observed in the first 2 Cohorts. Seven pts discontinued study treatment because of progression and 1 pt discontinued due to diagnosis of a second primary cancer during the first cycle. Non-hematological grade 2 or higher adverse events (AE), irrespective of causality, reported in ≥2 pts were: nausea, vomiting, abdominal pain, and bone pain, each observed in 2 pts (14%). Gr. 1 and 2 sinus bradycardia were reported in 6 (43%) and 1 pts (7%), respectively. One pt (7%) had grade 1 QT prolongation. No grade 4 AEs or treatment-related deaths were reported. For hematology and chemistry laboratory abnormalities: gr. 3 and 4 neutropenia in 7 pts (50%) and 2 pts (14%), respectively, gr. 3 thrombocytopenia in 1 pt (7%), gr. 3 anemia in 2 pts (14%). Grade 2 decrease in estimated glomerular filtration rate was observed in 7 pts (50%), all reported irrespective of causality. Co-administration of palbociclib had no meaningful impact on H3B-6545 exposure (15% and 21% increase in geometric means of AUC and Cmax, respectively). Co-administration of H3B-6545 modestly increased palbociclib exposure (49% and 36% increase in geometric means of AUC and Cmax, respectively). Among 6 response-evaluable pts in Cohort 1, 2 pts (33%) had confirmed partial responses and 4 pts (67%) had stable disease. Both responding pts received prior therapy with a CDK4/6 inhibitor and fulvestrant. Cohort 2 efficacy data is not yet mature. Recruitment is currently ongoing in Cohort 3 (H3B-6545 450 mg QD and palbociclib 125 mg QD). Conclusions: The combination of H3B-6545 (up to 300 mg dose) and palbociclib (up to 125 mg dose) was well-tolerated and demonstrated preliminary anti-tumor activity in heavily pretreated pts with ER+, HER2- mBC. ClinicalTrials.gov Identifier: NCT04288089.

Citation Format: Stephen Johnston, Timothy J Pluard, Judy S Wang, Erika P Hamilton, Dejan Juric, Catherine R Scholz, Elizabeth Hnitecki, Sara Dar, Lei Gao, Lisa Cantagallo, Manav Korpal, Jianjun Alan Xiao, Lihua Yu, Tarek Sahmoud, Antonio Gualberto. H3B-6545 in combination with palbociclib in women with metastatic estrogen receptor-positive (ER+), human epidermal growth factor receptor 2 (HER2)-negative breast cancer, phase 1b study [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 P1-17-03.

Abstract PD15-03: Overlapping molecular features (proliferation, immune signatures andTP53mutations) associated with palbociclib resistance inER+HER2- primary breast cancer

Background: Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors in combination with anti-hormone therapy are highly effective treatments for oestrogen receptor positive (ER+) and HER2 negative (HER2-) advanced breast cancer. Pre-clinical and clinical studies have reported mechanisms of resistance to CDK4/6 inhibitors to include interferon signalling, high CCNE1 expression and loss of RB1 expression. The PALLET phase II randomized neoadjuvant trial of letrozole (LET) ± palbociclib (PALBO) in postmenopausal ER+HER2- primary breast cancer showed that suppression of proliferation as measured by Ki67 was significantly greater with addition of PALBO to LET but did not result in all patients achieving complete cell-cycle arrest, indicating intrinsic resistance in some patients. We report phenotypes/genotypes associated with that resistance. Methods: In the PALLET trial, 307 patients were randomized to LET+PALBO (n=204) or LET (n=103) for 14wks. For the first 2wks of LET+PALBO patients were randomised to LET, PALBO or LET+PALBO. RNA-seq of baseline samples from consented patients was performed on fresh frozen biopsies for 224 patients (LET-only n=77; LET+PALBO n=147); whole exome sequencing was performed on 188 tumors and matched blood samples (LET-only n=61; LET+PALBO n=127). After 14wks of treatment, those patients with Ki67% &lt; 2.7% were classified as having complete cell-cycle arrest (CCCA). Differentially expressed genes (DEGs) were identified between patients sensitive (CCCA) and resistant (non-CCCA) to treatments with or without PALBO at 14wks by DESeq2. Mutect2 and VarScan was used to identify somatic mutations and CNVkit was used to identify copy number alterations in whole exome sequencing (WES). Results: In LET+PALBO treated patients, higher expression of E2F targets, interferon gamma response and mTORC1 signalling genes were observed in baseline gene expression of non-CCCA patients at 14wks (FDR&lt;0.05, GSEA). Similar results were also observed if using 2wk Ki67 data. In LET-only non-CCCA patients, higher expression of mTORC1 signalling and lower expression of oestrogen response genes (FDR&lt;0.05, GSEA) were observed. Additional analysis of baseline gene expression for non-CCCA at 14wks LET+PALBO patients showed higher expression of immune checkpoint inhibition associated genes including IFNG, IDO1, PD-L1 (FDR&lt;0.05, DESeq2), higher expression of genes expressed only in immune cells and two gene signatures related to interferon signalling and immune checkpoint blockade (FDR&lt;0.05, GSEA). Somatic mutation analysis showed a trend for enrichment of mutations in TP53 for both LET-only and LET+PALBO non-CCCA patients (p=0.02 and p=0.06, respectively, Fisher-exact) and significant enrichment of MAP3K1 mutations in LET-only CCCA patients (p&lt;0.05, Fisher-exact). TP53 mutations were also associated with higher proliferation, mTORC1 and immune related signatures (all p&lt;0.01, Mann-Whitney). Change at 14wks Ki67 was significantly different (p=0.02, Mann-Whitney) between TP53wt and TP53MUT for LET-only patients (median WT = -92%, MUT = -66%, p=0.02, Mann-Whitney ) but not for LET+PALBO (median WT = -99% MUT = -95%, p=0.13, Mann-Whitney). No copy number alterations were significantly enriched in LET+PALBO non-CCCA patients. Conclusion: We observe, confirming previous studies, an association of CDK4/6 inhibitor resistance, high expression of CCNE1 and genes related to interferon gamma signalling. We show that there is an overlap between resistance mechanisms and TP53 mutations. However, ER+HER2- patients with TP53 mutations may still benefit from PALBO adding to suppression of proliferation compared to LET-only treatment.

Citation Format: Eugene F Schuster, Hui Xiao, Maggie Cheang, Elena Lopez-Knowles, Lucy Kilburn, Viktoriya Korchina, Sejal Salvi, Samuel A Jacobs, Melanie Finnigan, David A Wheeler, Shannon Puhalla, Donna Muzny, Harsha Doddapaneni, Katherine Pogue-Geile, Yuan Liu, Judith Bliss, Stephen Johnston, Mitch Dowsett, Mothaffar Rimawi, On behalf of the PALLET Trialists. Overlapping molecular features (proliferation, immune signatures andTP53mutations) associated with palbociclib resistance inER+HER2- primary breast cancer [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 PD15-03.

Abstract PD2-07: Impact of using cross-platform gene expression profiling technologies and computational methods for intrinsic breast cancer subtyping in PALOMA-2 and PALLET

Background Intrinsic breast cancer molecular subtyping (IBCMS) provides significant prognostic information for patients (pts) with breast cancer (BC) treated with chemotherapy, human epidermal growth factor receptor 2 (HER2) targeted therapies, and endocrine therapies (ETs). Classifying tumors into intrinsic subtypes to determine optimal treatment is often applied using PAM50, commercially known as Prosigna. Meanwhile, Absolute Assignment of Breast Cancer Intrinsic Molecular Subtypes (AIMS) computational method was trained to predict PAM50-based IBCMS. As the PAM50 algorithm was developed to capture the major subtypes in a general pt population, clinicopathologic distribution of the study cohort and technology platform calibration should be considered in IBCMS analyses. This study compared different next-generation sequencing technologies and methodologic approaches of PAM50 on tumor samples from 2 randomized trials of postmenopausal women with estrogen receptor-positive (ER+)/HER2-negative (HER2-) BC. Methods PALOMA-2 is a double-blind, randomized study of first-line palbociclib (PAL) + letrozole (LET) for ER+/HER2- advanced BC (ABC). Tumor samples from consented pts were subtyped using the validated RUO PAM50 assay (ruoProsigna, NanoString); results were compared with published subtype results using AIMS on EdgeSeq Oncology Biomarker Panel (HTG Molecular Diagnostics). PALLET is a phase 2, randomized trial of PAL+LET as neoadjuvant therapy in pts with ER+ HER2- BC. Baseline frozen tumor biopsies underwent whole transcriptome mRNA-sequencing (mRNA-seq). IBCMS was performed using AIMS; PAM50 subtyping was performed on data normalised with subgroup-specific gene centering and microarray-RNA-sequencing calibration. Results In PALOMA-2, 222 pts had both ruoProsigna and AIMS data; an overall 54% agreement rate between methods was observed, with 46% (56/121) of Luminal B (LumB) subtype by ruoProsigna assigned as Luminal A (LumA) by AIMS and 67% (6/9) of basal-like by ruoProsigna as HER2-enriched (HER2-E) by AIMS (Table 1). In PALLET, 224 pts had mRNA-seq data; a 69% agreement between the two approaches (AIMS and PAM50) was observed, with only 4% (2/49) of LumB assigned as LumA by AIMS but 17% (26/156) and 16% (25/156) of LumA considered LumB or normal-like by AIMS, respectively. Progression-free survival (PFS) by ruoProsigna-derived subtype in PALOMA-2 showed that PAL+LET benefited all pts but those with a basal-like subtype (Table 2). With AIMS, PAL+LET provided a PFS benefit in pts with LumA and LumB subtypes, but was less effective in the HER2-E subtype. Conclusion Intrinsic subtyping has potential clinical utility. PAL+ET should be considered for ER+/HER2- ABC, except possibly in pts with a basal-like tumor, consistent with previous reports. A standardized clinical PAM50 assay and bioinformatics approach should be used as discrepancies in gene expression platforms and algorithms lead to different results and could misguide treatment decisions. Clinical trial identification: Pfizer (NCT01740427)

Table 1.Intrinsic Subtyping by IBCMS MethodsPALOMA-2PALLETMethodruoProsignaPAM50 mRNAseqAIMS BasalHER2LumALumBGrand TotalBasalHER2LumALumBNormalGrand TotalBasal-like, n (%)1 (11)NANANA13 (75)0001 (8)4HER2-E, n (%)6 (67)6 (30)6 (8)13 (10)311 (25)3 (100)8 (5)6 (12)1 (8)19LumA, n (%)NA2 (10)60 (83)56 (46)1180097 (62)2 (4)099LumB, n (%)2 (22)12 (60)3 (4)52 (43)690026 (17)41 (84)067Normal-like, n (%)NANA3 (4)NA30025 (16)010 (83)35Grand Total9 (100)20 (100)72 (100)121 (100)2224 (100)3 (100)156 (100)49 (100)12 (100)224NA=Not available

Table 2.Median PFS statistics by subtype in PALOMA-2PAL+LET PFS, monthsPBO+LET PFS, monthsHazard Ratio(95% CI)P ValueruoProsignaBasal-like8.2 (n=5)3.6 (n=4)0.39 (0.09-1.77)0.206HER2-E11.0 (n=12)5.1 (n=8)0.41 (0.15-1.11)0.071LumA37.2 (n=52)13.6 (n=20)0.42 (0.21-0.84)0.011LumB27.6 (n=79)13.8 (n=42)0.63 (0.40-1.00)0.049AIMSBasal-likeNANANANAHER2-E16.4 (n=21)8.4 (n=10)0.82 (0.32-2.1)0.684LumA30.6 (n=84)16.5 (n=34)0.56 (0.33-0.95)0.029LumB19.3 (n=41)8.8 (n=28)0.39 (0.23-0.67)&lt;0.001NA=Not available; PBO=placebo

Citation Format: Maggie Cheang, Mitch Dowsett, Mothaffar Rimawi, Stephen Johnston, Samuel Jacobs, Judith Bliss, Katherine Pogue-Geile, Lucy Kilburn, Zhou Zhu, Eugene F. Schuster, Hui Xiao, Lisa Swaim, Shibing Deng, Dongrui R. Lu, Eric Gauthier, Jennifer Tursi, Dennis J. Slamon, Hope S. Rugo, Richard S. Finn, Yuan Liu. Impact of using cross-platform gene expression profiling technologies and computational methods for intrinsic breast cancer subtyping in PALOMA-2 and PALLET [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 PD2-07.

Abstract P1-17-08: Abemaciclib and endocrine therapy for hormone receptor-positive, HER2-negative advanced breast cancer: A real-world UK multicentre experience

Background Abemaciclib is approved in 1st and 2nd line for hormone receptor (HR)-positive HER2-negative advanced breast cancer (ABC). However, outcomes on this agent are unclear in the real world.We determined the safety and efficacy profile of abemaciclib across 15 institutions in the United Kingdom. Methods We retrospectively identified HR-positive, HER2-negative ABC patients who received abemaciclib between July 2018 and June 2020. Demographics, disease characteristics, prior treatments, blood tests, toxicities, treatment delays and responses were recorded. Simple statistics, Fisher’s exact test, chi-squared method and Cox regression were used as appropriate. Results 228 patients identified had median age of 64 (31-93). 172 (75.4%) were postmenopausal and 209 (91.7%) had ECOG Performance Status 0-1. 145 (63.6%) had visceral involvement and 44 (19.3%) only bone disease. Patients received a median 1 (range 0-7) prior lines of treatment and 0 (range 0-5) prior chemotherapy lines.148 patients (64.9%) experienced diarrhoea (grade ≥3 in 16 [7.0%]). 146 patients (64.0%) developed neutropenia (grade ≥3 in 40 [17.5%]). 5 experienced febrile neutropenia (2.2%). 32 patients (14.0%) required hospitalisation due to toxicity (diarrhoea in 9 [3.95%]).Dose reductions were required in 107 patients (46.9%), mainly due to diarrhoea (55 [24.1%]) and to 50mg BD in 30 patients (13.2%). Dose delays were in median 14 (range 2-118). Abemaciclib was discontinued in 121 patients (53.1%) due to disease progression in 61 (26.7%) and toxicity in 48 (21.0%) (diarrhoea in 16 [7.0%]).Abemaciclib produced clinical benefit rate of 82.8% and overall response rate of 47.2% in 163 patients assessed. Overall, median progression-free survival (PFS) was 6.4 months (95% confidence interval [CI] 4.4-7.8) and median overall survival (OS) was 8.8 months (95% CI 7.6-10.6). Conclusions This a large real-world analysis of the safety and efficacy of abemaciclib in combination with endocrine therapy for advanced HR-positive breast cancer. In this analysis, the rates of diarrhoea were lower compared with the pivotal trial data, while neutropenia was more frequent. Although the PFS outcomes were similar to those previously reported, median OS was worse in this cohort which may reflect the different population of patients included, who were older and had more frequent visceral involvement. The selection of patients suitable for abemaciclib is crucial to ensure adequate efficacy and safety outcomes in this setting.

Citation Format: Nicolò Matteo Luca Battisti, Laura Morrison, Tamsin Nash, Nishanti Senthivel, Samantha Kestenbaum, Parvin Begum, Mariam Obeid, William Hayhurst, Dorothy Yang, Shafiah Gafoor, Caroline Brown, Farah Rehman, Laura Kenny, Olivia Hatcher, Susan Susan, Jennet Williams, Anna Brown, Hamoun Rozati, Alexandros Alexandros, Elinor Sawyer, Charalampos Gousis, Eleni Karapanagiotou, Anna Rigg, Kleopatra Rapti, Rebecca Roylance, Mark Beresford, Abigail L Gee, Apostolos Konstantis, Judy King, Mark Nathan, Emma Spurrell, Mark Pearce, Dane Bradwell, Arshi Denton, Kate Swain, Sophie McGrath, Mark Allen, Alistair Ring, Stephen Johnston, Fharat Raja. Abemaciclib and endocrine therapy for hormone receptor-positive, HER2-negative advanced breast cancer: A real-world UK multicentre experience [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 P1-17-08.

Clinical outcomes in patients with triple negative or HER2 positive lobular breast cancer: a single institution experience

PURPOSE

Invasive lobular carcinomas (ILC) are characterised by loss of the cell adhesion molecule E-cadherin. Approximately 15% of ILC are ER negative at the time of breast cancer diagnosis, or at relapse due to loss of ER expression. Less than 5% of classical ILC but up to 35% of pleomorphic ILC are HER2 positive (HER2+).

METHODS

Retrospective analysis of clinic-pathological data from patients with Triple negative (TN) or HER2+ ILC diagnosed 2004-2014 at the Royal Marsden Hospital. The primary endpoint was median overall survival (OS) in patients with metastatic disease. Secondary endpoints included response rate to neo-adjuvant chemotherapy (NAC), median disease-free interval (DFI) and OS for patients with early disease.

RESULTS

Three of 16 patients with early TN ILC and 7/33 with early HER2+ ILC received NAC with pCR rates of 0/3 and 3/5 patients who underwent surgery, respectively. Median DFI was 28.5 months [95% Confidence interval (95%CI) 15-78.8] for TN ILC and not reached (NR) (111.2-NR) for HER2+ early ILC. Five-year OS was 52% (95%CI 23-74%) and 77% (95%CI 58-88%), respectively. Twenty-three patients with advanced TN ILC and 14 patients with advanced HER2+ ILC were identified. Median OS was 18.3 months (95%CI 13.0-32.8 months) and 30.4 months (95%CI 8.8-NR), respectively.

CONCLUSIONS

In our institution we report a high relapse rate after treatment for early TN ILC, but median OS from metastatic disease is similar to that expected from TN IDC. Outcomes for patients with advanced HER2+ ILC were less favourable than those expected for IDC, possibly reflecting incomplete exposure to anti-HER2 therapies.

CLINICAL TRIAL REGISTRATION

ROLo (ClinicalTrials.gov Identifier: NCT03620643), ROSALINE (ClinicalTrials.gov Identifier: NCT04551495).

Biomarkers of Response and Resistance to Palbociclib Plus Letrozole in Patients With ER+/HER2- Breast Cancer

PURPOSE

To determine (i) the relationship between candidate biomarkers of the antiproliferative (Ki67) response to letrozole and palbociclib alone and combined in ER⁺/HER2^- breast cancer; and (ii) the pharmacodynamic effect of the agents on the biomarkers.

EXPERIMENTAL DESIGN

307 postmenopausal women with ER⁺/HER2^- primary breast cancer were randomly assigned to neoadjuvant treatment with letrozole for 14 weeks; letrozole for 2 weeks, then letrozole+palbociclib to 14 weeks; palbociclib for 2 weeks, then letrozole+palbociclib to 14 weeks; or letrozole+palbociclib for 14 weeks. Biopsies were taken at baseline, 2 and 14 weeks and surgery at varying times after stopping palbociclib. Immunohistochemical analyses were conducted for Ki67, c-PARP, ER, PgR, RB1, CCNE1, and CCND1.

RESULTS

Higher baselines ER and PgR were significantly associated with a greater chance of complete cell-cycle arrest (CCCA: Ki67 <2.7%) at 14 weeks and higher baseline Ki67, c-PARP, and CCNE1 with a lower chance. The interaction with treatment was significant only for c-PARP. CCND1 levels were decreased c.20% by letrozole at 2 and 14 weeks but showed a tendency to increase with palbociclib. CCNE1 levels fell 82% (median) in tumors showing CCCA but were unchanged in those with no CCCA. Only 2/9 tumors showed CCCA 3-9 days after stopping palbociclib. ESR1 mutations were found in 2/4 tumors for which surgery took place ≥6 months after starting treatment.

CONCLUSIONS

High CCNE1 levels were confirmed as a biomarker of resistance to letrozole+palbociclib. Ki67 recovery within 3-9 days of discontinuing palbociclib indicates incomplete suppression of proliferation during the "off" week of its schedule.

Antibiotic toxicity on human spermatozoa assessed using the sperm DNA fragmentation dynamic assay

Sperm DNA fragmentation (SDF) dynamic assays were piloted on 4 fresh ejaculates to examine the possible sperm toxicity of three common antibiotics, ciprofloxacin, doxycycline and ampicillin, incubated at a concentration estimated to be reached in semen in vivo, and 100×, for 24 h. SDF was assessed in terms of single-strand DNA breaks (SSBs) and double-strand DNA breaks (DSBs). Low and high concentrations of ciprofloxacin and high concentration of doxycycline significantly increased the SDF rate, due to sperm containing SSBs. Ampicillin did not affect SDF dynamics at any dose. Based on these results, the effect of antibiotics on the global-SDF dynamics was further examined in 21 ejaculates assessed at 0, 4 and 6 h. Ciprofloxacin increased the rate of SDF at the low concentration in 17 from 21 subjects; the high concentration resulted in a stronger effect in all individuals. A significant increase in the rate of SDF in 17 ejaculates was also noted when spermatozoa were incubated with the high concentration of doxycycline. The dynamic SDF assay is a rapid and sensitive tool to evidence sperm toxicity. Ciprofloxacin should be avoided when it is necessary to preserve sperm quality for reproductive purposes and as additive in semen diluents.

Hybridization of Bogoliubov Quasiparticles between Adjacent CuO_{2} Layers in the Triple-Layer Cuprate Bi_{2}Sr_{2}Ca_{2}Cu_{3}O_{10+δ} Studied by Angle-Resolved Photoemission Spectroscopy

Hybridization of Bogoliubov quasiparticles (BQPs) between the CuO_{2} layers in the triple-layer cuprate high-temperature superconductor Bi_{2}Sr_{2}Cu_{2}Cu_{3}O_{10+δ} is studied by angle-resolved photoemission spectroscopy (ARPES). In the superconducting state, an anticrossing gap opens between the outer- and inner-BQP bands, which we attribute primarily to interlayer single-particle hopping with possible contributions from interlayer Cooper pairing. We find that the d-wave superconducting gap of both BQP bands smoothly develops with momentum without an abrupt jump in contrast to a previous ARPES study. Hybridization between the BQPs also gradually increases in going from the off nodal to the antinodal region, which is explained by the momentum dependence of the interlayer single-particle hopping. As possible mechanisms for the enhancement of the superconducting transition temperature, the hybridization between the BQPs as well as the combination of phonon modes of the triple CuO_{2} layers and spin fluctuations represented by a four-well model are discussed.

Plasma progesterone secretion during gestation of the captive short-beaked echidna

This study describes the progesterone profile during pregnancy in sexually mature female captive short-beaked echidnas (Tachyglossus aculeatus aculeatus). Echidnas were monitored daily by video surveillance to confirm key reproductive behaviour. Plasma samples were collected and pouch morphology was assessed three times a week. The pouch of the female echidna only develops during gestation and it was possible to create a four-stage grading system using the most distinguishable characteristics of pouch development. Maximum pouch development was associated with declining progesterone concentrations, with the pouch closing in a drawstring-like manner at oviposition. Control of pouch development in pregnant echidnas is not yet clear but later pouch development is associated with a decrease in progesterone and pouch closure and may be under mechanical influences of the egg or young in the pouch. The length of pregnancy was 16.7 ± 0.2 days with a 15.1 ± 1.0 days luteal phase followed by an incubation period in the pouch. Eggs could be detected in utero at least 4 days before oviposition. Plasma progesterone peaked at 10.5 ± 0.9 ng/mL within 12 days of mating but then declined to basal levels within 1 day of oviposition and remained basal throughout egg incubation, confirming that progesterone is elevated throughout pregnancy and that gestation does not extend beyond the luteal phase. After the loss of an egg or pouch young, most females entered a second oestrous cycle and ovulated, suggesting echidnas are seasonally polyoestrous. The duration of the luteal phase in the echidna corresponds with that observed in other mammals.

AAV ablates neurogenesis in the adult murine hippocampus

Recombinant adeno-associated virus (rAAV) has been widely used as a viral vector across mammalian biology and has been shown to be safe and effective in human gene therapy. We demonstrate that neural progenitor cells (NPCs) and immature dentate granule cells (DGCs) within the adult murine hippocampus are particularly sensitive to rAAV-induced cell death. Cell loss is dose dependent and nearly complete at experimentally relevant viral titers. rAAV-induced cell death is rapid and persistent, with loss of BrdU-labeled cells within 18 hr post-injection and no evidence of recovery of adult neurogenesis at 3 months post-injection. The remaining mature DGCs appear hyperactive 4 weeks post-injection based on immediate early gene expression, consistent with previous studies investigating the effects of attenuating adult neurogenesis. In vitro application of AAV or electroporation of AAV2 inverted terminal repeats (ITRs) is sufficient to induce cell death. Efficient transduction of the dentategyrus (DG)– without ablating adult neurogenesis– can be achieved by injection of rAAV2-retro serotyped virus into CA3. rAAV2-retro results in efficient retrograde labeling of mature DGCs and permits in vivo two-photon calcium imaging of dentate activity while leaving adult neurogenesis intact. These findings expand on recent reports implicating rAAV-linked toxicity in stem cells and other cell types and suggest that future work using rAAV as an experimental tool in the DG and as a gene therapy for diseases of the central nervous system should be carefully evaluated.

Abemaciclib as initial therapy for advanced breast cancer: MONARCH 3 updated results in prognostic subgroups

In MONARCH 3, continuous dosing of abemaciclib with an aromatase inhibitor (AI) conferred significant clinical benefit to postmenopausal women with HR+, HER2- advanced breast cancer. We report data for clinically prognostic subgroups: liver metastases, progesterone receptor status, tumor grade, bone-only disease, ECOG performance status, and treatment-free interval (TFI) from an additional 12-month follow-up (after final progression-free survival [PFS] readout). In the intent-to-treat population, after median follow-up of approximately 39 months, the updated PFS was 28.2 versus 14.8 months (hazard ratio [HR], 0.525; 95% confidence interval, 0.415-0.665) in abemaciclib versus placebo arms, respectively. Time to chemotherapy (HR, 0.513), time to second disease progression (HR, 0.637), and duration of response (HR, 0.466) were also statistically significantly prolonged with the addition of abemaciclib to AI. Treatment benefit was observed across all subgroups, as evidenced by objective response rate change from the addition of abemaciclib to AI, with the largest effects observed in patients with liver metastases, progesterone receptor-negative tumors, high-grade tumors, or TFI < 36 months. Extended follow-up in the MONARCH 3 trial further confirmed that the addition of abemaciclib to AI conferred significant treatment benefit to all subgroups, including those with poorer prognosis.

Economic Analysis of Leak Complications in Anastomoses Performed with Powered versus Manual Circular Staplers in Left-Sided Colorectal Resections: A US-Based Cost Analysis

Purpose

To estimate the cost impact of using the ECHELON CIRCULAR™ Powered Stapler (ECP) compared with manual circular staplers (standard of care, SOC) among patients undergoing colectomy procedures that involve left-sided anastomosis.

Methods

A US hospital-based budget impact model was developed to estimate the impact of ECP in reducing the surgical complication of anastomotic leak. The incremental acquisition cost of ECP vs SOC was compared to the net potential savings from reduced complication costs. The model was based on complication rates from a recently published matching-adjusted indirect comparison (MAIC) that compared clinical and healthcare utilization outcomes of patients using ECP with those of a propensity score-matched retrospective SOC control cohort from a real-world clinical practice population. The model assessed total cost, average length of stay (LOS), proportion of patients with a non-home discharge, and all-cause readmission. Deterministic (DSA) and probabilistic sensitivity analyses (PSA) were conducted to evaluate the robustness of the model assumptions and inputs.

Results

Despite a higher device cost of $412 for ECP compared with $298 for a manual stapler, annual savings due to avoided complications with ECP was $53,987 for anastomotic leak, assuming 100 procedures per year with each type of circular stapler. ECP also helped to avoid 27 LOS days, 0.38 readmissions and 0.22 non-home discharges. Sensitivity analyses around potential drivers of costs established the robustness of economic savings with the use of ECP - with annual savings being most impacted by the probability of anastomotic leak complication in the DSA.

Conclusion

This model demonstrates that among patients undergoing left-sided colectomy procedures, the incremental cost of using the ECHELON CIRCULAR™ Powered Stapler instead of a manual circular stapler was offset by the savings from lowered incidence and cost of management of anastomotic leaks in the hospital setting.

Comparison of clinical and economic outcomes between minimally invasive liver resection and open liver resection: a propensity-score matched analysis

BACKGROUND

Minimally invasive liver resection (MILR) has gained momentum in recent years. This study of contemporary data compares economic and clinical outcomes between MILR and open liver resection (OLR).

METHODS

We extracted data for patients undergoing liver resection between October 2015-September 2018 from the Premier Healthcare Database. We conducted a propensity score matched analysis to compare complications, in-hospital mortality, inpatient readmissions, discharge to institutional post-acute care, operating room time (ORT), length of stay (LOS), and total hospital cost between MILR and OLR patients.

RESULTS

From the eligible OLR (n = 3349) and MILR (n = 1367) patients, we propensity score matched 1261 from each cohort at a 1:1 ratio. After matching, MILR was associated with lower rates of complications (bleeding: 8.2% vs. 17.4%; respiratory failure: 5.5% vs. 10.9%; intestinal obstruction: 3.6% vs. 6.0%, and pleural effusion: 1.9% vs. 4.9%), in-hospital mortality (0.5% vs. 3.0%), 90-day inpatient readmissions (10.4% vs. 14.3%), discharge to institutional post-acute care (6.9% vs. 12.3%), shorter ORT (257 vs. 308 min) and LOS (4.3 vs. 7.2 days), and lower hospital costs ($19463 vs. $29119) (all P < 0.001).

CONCLUSION

MILR was associated with lower risk of complications and reduced hospital resource utilizations as compared with OLR.

Accurate Determination of the Neutron Skin Thickness of ^{208}Pb through Parity-Violation in Electron Scattering

We report a precision measurement of the parity-violating asymmetry A_{PV} in the elastic scattering of longitudinally polarized electrons from ^{208}Pb. We measure A_{PV}=550±16(stat)±8(syst) parts per billion, leading to an extraction of the neutral weak form factor F_{W}(Q^{2}=0.00616  GeV^{2})=0.368±0.013. Combined with our previous measurement, the extracted neutron skin thickness is R_{n}-R_{p}=0.283±0.071  fm. The result also yields the first significant direct measurement of the interior weak density of ^{208}Pb: ρ_{W}^{0}=-0.0796±0.0036(exp)±0.0013(theo)  fm^{-3} leading to the interior baryon density ρ_{b}^{0}=0.1480±0.0036(exp)±0.0013(theo)  fm^{-3}. The measurement accurately constrains the density dependence of the symmetry energy of nuclear matter near saturation density, with implications for the size and composition of neutron stars.

The effect of Chlamydia infection on koala (Phascolarctos cinereus) semen quality

Although it is well established that chlamydial disease renders female koalas infertile, there has been limited research on its effects on male koala fertility, specifically sperm quality. This study determined whether chlamydial infection adversely affects semen quality of naturally infected koalas and spermatozoa recovered from Chlamydia negative koalas co-incubated in vitro with C. pecorum elementary bodies (EBs). Semen from 102 south-east Queensland sexually mature wild koalas exhibiting varying degrees of chlamydiosis and clinical signs of disease were assessed for semen quality and compared to 11 clinically healthy, Chlamydia-free captive male koalas. For in vitro studies, semen samples were collected from 6 Chlamydia-free captive koalas, and co-incubated over 24 h with high and low concentrations of C. pecorum EBs and sperm quality assessed. Wild koalas displaying severe signs of clinical disease with C. pecorum present in the semen had significantly greater sperm DNA damage (P = 0.0267). The total % of morphologically abnormal spermatozoa was highest in wild koalas that had severe signs of clinical disease but whose semen was negative for C. pecorum (P = 0.0328). This apparent contradiction is possibly associated with wild males having resolved the infection but still possessing underlining reproductive pathology. A higher incidence of loose head spermatozoa occurred in semen of wild koalas not infected with C. pecorum compared to those that were C. pecorum infected (P = 0.026). In vitro incubation of semen with C. pecorum significantly decreased sperm motility and viability over 24 h.

Cutaneous toxicities occurring during palbociclib (CDK4/6 inhibitor) and endocrine therapy in patients with advanced breast cancer: a single-centre experience

PURPOSE

Treatment with Palbociclib, a cyclin-dependent kinase 4/6 inhibitor, has demonstrated significantly improved progression-free survival in patients with hormone receptor-positive, HER2-negative, advanced breast cancer, when used in combination with letrozole or fulvestrant endocrine therapies. However, limited information exists on its cutaneous adverse effects (AE). Hence, we conducted a retrospective cohort study to investigate the prevalence and management of cutaneous AE during palbociclib and endocrine therapy.

METHOD

We included 324 adult patients with advanced breast cancer who received palbociclib between March 2016 and August 2020 within a tertiary comprehensive cancer centre. Patient demographics, details of previous and concurrent treatments, as well as treatment-related cutaneous AE were recorded from electronic records.

RESULTS

The incidence of treatment-related cutaneous AE was 14.2% (46 from a total of 324 patients). The most frequent cutaneous reactions included maculopapular rash (41%), asteatosis (37%), pruritus and urticaria (20%), and bullous dermatitis reactions (9%). We identified two patients with treatment-induced subacute cutaneous lupus erythematosus, one case of bullous pemphigoid, and a single erythema multiforme. Patients received an average of 9 cycles of treatment, completing an average of 6 cycles before developing cutaneous AE, which persisted for a median of 43 days. Only 15% (n = 7) of affected patients required temporary suspension, and 4% (n = 2) required discontinuation. The majority were managed with potent topical steroids, with oral corticosteroids being required in 3 patients, and one patient required hydroxychloroquine.

CONCLUSION

Our study describes both the spectrum of cutaneous AE of palbociclib and endocrine therapy, and approaches to management. Prompt management may limit the negative impact on patients, facilitating beneficial continuation of palbociclib and endocrine therapy.

Abstract PS5-01: Biomarkers of resistance to palbociclib in ER+ primary breast cancer in the PALLET trial

Background: CDK4/6 inhibitors are being used in combination with aromatase inhibitors as therapy for advanced ER+ breast cancer (BC) and are being explored for use in primary BC. Few mechanisms driving resistance to added CDK4/6 inhibitors have been defined. The PALLET phase II randomized neoadjuvant trial of letrozole (LET) ± palbociclib (PALBO) in postmenopausal ER+HER2- primary BC reported that clinical response rate over 14wks was not significantly increased by adding PALBO to LET but suppression of Ki67 was significantly increased (Johnston et al, JCO 2018, 37, 178): after 14wks complete cell cycle arrest (CCCA, Ki67&lt;2.7%) was present in 59% on LET and 90% on LET+PALBO. Here we sought to identify biomarkers of de novo resistance to allow selection of patients most likely to benefit from added PALBO.

Methods: 307 patients were randomized to LET (n=103) or LET+PALBO (n=204) for 14 wks. The first 2wks of LET+PALBO patients were randomised to LET, PALBO, or LET+PALBO. Biopsies were taken at baseline, 2wks and 14wks. Biomarker data are presented here for baseline only, other than Ki67 at both baseline and 14wks. IHC analyses were conducted on FFPE biopsies for ER, PgR, RB1, cyclin-E1, and cyclin-D1 (also FISH). RNA-seq was performed on fresh frozen biopsies. Association of each biomarker with CCCA was determined by logistic regression. Differentially expressed genes (DEGs) were identified between patients sensitive (CCCA) (n=94) and resistant (non-CCCA) (n=10) to treatments with or without PALBO at 14wks by DESeq2. Fifty hallmark gene sets were tested for significant enrichment with DEGs and differential gene sets were identified by using Gene Set Enrichment Analysis (GSEA).

Results: The association of IHC biomarkers with CCCA is shown in the table. Lower levels of ER, higher levels of cyclin-E1, and amplification of cyclin-D1 were each significantly associated with a greater chance of non-CCCA with LET+PALBO. High cyclin-E1 levels were also associated with reduced chance of CCCA with LET only. Patients with high baseline Ki67 also exhibited higher non-CCCA with LET+PALBO at 14wks (p=0.0002). In the RNAseq data we identified 1973 DEGs between the 14wk CCCA and non-CCCA patients for LET+PALBO. E2F and MYC targets, PI3K/AKT/MTOR signalling and interferon response gene sets were among the hallmark gene sets enriched for genes with higher expression in non-CCCA patients at 14wks for LET+PALBO (FDR&lt;0.05). For LET-only, 311 DEGs were identified and the “Estrogen Response Early” gene set was significantly enriched in genes with higher expression in CCCA samples. At the individual gene level, genes significantly associated with non-CCCA after 14wks LET+PALBO included CCNE1, CDK2 and several E2F-related genes (p&lt;0.05). Their expression was not significantly different between non-CCCA and CCCA patients with LET alone.

Conclusion: Biomarkers associated with response/resistance to added PALBO were different from LET only. PALBO resistance was associated with higher baseline expression of cyclin-E1 (both IHC and RNA), CDK2, and genes related to E2F, MYC, interferon and MTOR signalling. These results suggest that multiple identifiable mechanisms of de novo resistance to PALBO are likely to exist in primary ER+ BC. On-going WES analyses will allow the significance of alterations at the DNA level to be presented.

Table 1.Continuous measurement in a logistic regression for CCCA at 14 weeks; Oddsratio calculated separately for group A and groups B,C,D and were adjusted forregion (UK vs NA); * amplified vsnon-amplifiedContinuous measurement in a logistic regression for CCCA at 14 weeksBiomarkerLET LET+PALBOOdds ratio95% CIpOdds ratio95% CIpER1.120.36, 3.480.844.471.62, 12.380.004PgR4.381.03, 18.580.053.050.50, 18.560.23RB13.010.24, 38.560.400.420.05, 38.490.83Cyclin-E10.100.01, 0.840.030.020.00, 0.200.001Cyclin-D1 IHC3.090.51, 18.490.222.560.28, 23.330.40CyclinD1 FISH*1.470.43, 4.990.530.280.06, 0.860.03

Citation Format: Eugene F Schuster, Hui Xiao, Elena Lopez-Knowles, Lucy Kilburn, Mothaffar Rimawi, David A Wheeler, Katherine Pogue-Geile, Yuan Lui, Samuel A Jacobs, Chet Cornman, Shannon Puhalla, Maggie Cheang, Judith Bliss, Stephen Johnston, Mitch Dowsett, On behalf of the PALLET Trialists. Biomarkers of resistance to palbociclib in ER+ primary breast cancer in the PALLET trial [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS5-01.

Abstract PD2-01: High Ki-67 as a biomarker for identifying patients with high risk early breast cancer treated in monarchE

Background monarchE, a phase 3, open-label, randomized study evaluating endocrine therapy with or without abemaciclib in patients with node positive, HR+, HER2-, high risk early breast cancer, resulted in a statistically significant improvement in invasive disease-free survival (IDFS) at a pre-planned interim analysis. Ki-67, a marker of cellular proliferation in breast cancer, was used in addition to other clinical and/or pathological features to identify patients whose cancer may be at higher risk of recurrence. A key secondary endpoint was to evaluate IDFS in patients with high (≥20%) Ki-67 tumors. Methods Patients with ≥4 positive nodes, or 1-3 nodes and either grade 3 disease, tumor size ≥5 cm, or central Ki-67 ≥20% were eligible for monarchE. Ki-67 was centrally assessed for all eligible patients with suitable untreated breast tissue using a standardized kit produced by Agilent/Dako (MIB-1). A sequential gatekeeping strategy was utilized to test the statistical significance in IDFS for patients with high Ki-67 tumors. Data on this subgroup are presented. Results Primary outcome results in the ITT population are presented separately and resulted in a significant 28.7% reduction in the risk of developing invasive disease with abemaciclib plus ET versus ET alone (HR = 0.713; 95% CI = 0.583, 0.871). Of the 5637 patients enrolled in monarchE, 4425 (78.5%) had Ki-67 samples eligible for testing. Of those tested, 2498 patients (56.5%) had Ki-67 ≥20% (Ki-67H). Results from the Ki-67H population are presented separately and showed that abemaciclib plus ET demonstrated superior IDFS versus ET alone with a 30.9% reduction in the risk of invasive disease (p=.0111; HR = 0.691; 95% CI = 0.519, 0.920). There was an absolute improvement of 4.5% in IDFS rate at 2 years (91.6% in the abemaciclib arm and 87.1% in the control arm). An additional planned analysis was performed evaluating efficacy in 2003 patients with high Ki-67 tumors enrolled in cohort 1 (patients with ≥4 positive nodes or 1-3 nodes and either tumor size ≥5 cm and/or grade 3 disease). The IDFS treatment benefit in this group was statistically significant with a HR of 0.643 (95% CI = 0.475, 0.872) corresponding to a 35.7% reduction in the risk of developing invasive disease. Two-year IDFS rates in this group were 91.3% in the abemaciclib group and 86.1% in the control arm, representing a 5.2% absolute improvement at 2 years. A clinically meaningful improvement was also observed in distant relapse-free survival (DRFS) in both populations. Baseline characteristics were balanced across arms in both Ki-67H populations. An exploratory analysis was conducted evaluating patients in cohort 1 with low Ki-67 (&lt;20%) and will be presented.

Conclusion This represents the first time a prespecified threshold of ≥20% for Ki-67 has been used to prospectively evaluate the utility of Ki-67 in a phase III registration trial with a standardized assay. There was a statistically significant improvement in IDFS for patients with high Ki-67 tumors across the ITT population (HR = 0.691) and in cohort 1 (HR = 0.643). These results suggest that Ki-67 ≥20% is an additional clinicopathological feature that can be used in conjunction with high risk features of nodal involvement, tumor size, and grade, to select patients with a higher risk of recurrence who may benefit from treatment with abemaciclib in the adjuvant setting. ClinicalTrials.gov: NCT03155997

Ki-67H Ki-67H Cohort 1EndpointAbemaciclib + ETN=1262ET aloneN=1236Abemaciclib + ETN=1017ET aloneN=986IDFS# events, n (%)82 (6.5)115 (9.3)71 (7.0)106 (10.8)log rank Pvalue, HR (95% CI)p=.0111 0.691 (0.519, 0.920)p=.00420.643 (0.475, 0.872)Rate (%) at 2-years (95% CI)91.6(89.4, 93.4)87.1(84.3, 89.5)91.3(88.9, 93.2)86.1(83.1, 88.7)DRFS# events, n (%)65 (5.2)102 (8.3)56 (5.5)96 (9.7)log rank Pvalue,HR (95% CI)p=.0018 0.609 (0.445, 0.833)p=.00040.554 (0.397, 0.773)Rate (%) at 2 years (95% CI)93.6(91.6, 95.1)88.5(85.7, 90.7)93.3(91.2, 95.0)87.384.4, 89.8)

Citation Format: Nadia Harbeck, Stephen Johnston, Peter Fasching, Miguel Martin, Masakazu Toi, Priya Rastogi, Chuangui Song, David Molthrop, Jacqueline Vuky, Toshinari Yamashita, Georgina Garnica Jaliffe, Mahmut Gumus, Desiree Headley, Ran Wei, Susana Barriga, Maria Munoz, Michael Method, Valerie Andre, Hans Kreipe, Joyce O'Shaughnessy. High Ki-67 as a biomarker for identifying patients with high risk early breast cancer treated in monarchE [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD2-01.