First Measurements of the Double-Polarization Observables F, P, and H in ω Photoproduction off Transversely Polarized Protons in the N^{*} Resonance Region

First measurements of double-polarization observables in ω photoproduction off the proton are presented using transverse target polarization and data from the CEBAF Large Acceptance Spectrometer (CLAS) FROST experiment at Jefferson Lab. The beam-target asymmetry F has been measured using circularly polarized, tagged photons in the energy range 1200-2700 MeV, and the beam-target asymmetries H and P have been measured using linearly polarized, tagged photons in the energy range 1200-2000 MeV. These measurements significantly increase the database on polarization observables. The results are included in two partial-wave analyses and reveal significant contributions from several nucleon (N^{*}) resonances. In particular, contributions from new N^{*} resonances listed in the Review of Particle Properties are observed, which aid in reaching the goal of mapping out the nucleon resonance spectrum.

Abstract P2-07-05: A clinical calculator to predict disease outcomes in women with hormone receptor-positive advanced stage breast cancer treated with first-line endocrine therapy

Purpose: Endocrine based therapy is an effective strategy to manage hormone receptor-positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer (ABC). However, nearly all patients exhibit/develop either de novo or acquired resistance. While prognostic biomarkers of endocrine responsiveness are well established for the adjuvant treatment in ER+ breast cancer, less is known regarding prognostic and predictive biomarkers of response in the first line ABC setting. We sought to develop a clinical calculator based on clinical criteria for predicting progression-free survival (PFS) and overall survival (OS) of women with HR+/HER2- ABC who will be receiving endocrine monotherapy as first-line treatment for ABC.

Methods: The development of the clinical calculator will be based on data from modern clinical trials in women with HR+/HER2- ABC. The studies to be included in the final analyses are given in Table 1. The control arm data from trials1-6 will form the training dataset (N = 1,223) and be used to construct the clinical prediction models. Variables considered include age, race, ECOG status, disease measurability, body mass index, disease-free interval, number of metastatic sites, locations of metastatic sites, prior endocrine therapy, and prior chemotherapy. Missing values will be imputed using single imputation with all variables included in the imputation model. For continuous variables, restricted cubic splines will be used to determine if non-linear effects may be more appropriate. The Lasso regression will be used as a variable selection technique to reduce the dimensionality of covariates; initially all pairwise interactions will be included in the model. Following Lasso regression, the multivariable Cox proportional hazards models will be constructed for PFS and OS including only variables retained in Lasso. The final model will be internally validated for discrimination and calibration using 10-fold cross-validation. External validation will be performed using control arm data from EGF 30008 (N = 536).

Results: To date, control arm data from four trials (trials 1-4) have been received. The preliminary results presented here are based on pooled data from C40503 and LEA, for which data elements have been harmonized. Models for predicting PFS and OS have good calibration and are associated with bias-corrected C-indices of 0.61 and 0.65, respectively. These models will be updated using pooled data from trials 1-6.

Conclusions: Our preliminary data demonstrate that clinical calculators based on baseline clinical factors can provide accurate prediction of PFS and OS in patients with HR+/HER2- ABC treated with first-line ET. If validated, these tools may be used for risk stratification in future clinical trials and to identify patients who may require more or less aggressive therapy.

Table 1:Studies to be includedTrial NumberTrial NameTrial PISample Size in Control Arm1C40503Maura Dickler152 (letrozole)2LEAMiguel Martin179 (letrozole)3FACTJonas Bergh188 (anastrozole)4FALCONJohn Robertson194 (anastrozole)5S0226Rita Mehta345 (anastrozole)6MONARCH 3Matthew Goetz165 (nonsteroidal AI)7EGF 30008Stephen Johnston536 (letrozole)

Citation Format: Polley M-YC, Dickler MN, Johnston S, Goetz MP, de la Haba J, Loibl S, Mehta RS, Bergh J, Roberston J, Barlow W, Liu H, Tenner K, Martin M. A clinical calculator to predict disease outcomes in women with hormone receptor-positive advanced stage breast cancer treated with first-line endocrine therapy [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-07-05.

Abstract P4-13-13: Meta-analyses of visceral versus non-visceral metastases treated by AI & SERD agents as 2nd line endocrine therapy (ET) for HR+ breast cancer (BC)

There is a prevailing belief that ET for HR+ advanced BC is not as effective in patients with visceral metastases (VM) compared to non-visceral metastases (nVM), particularly with later lines of ET. Recently fulvestrant 500mg (Ful 500), has been reported to have greater efficacy in nVM compared to i) VM treated by Ful 500 but also compared to ii) nVM treated by Ful 250 (2nd line) and iii) nVM treated by aromatase inhibitor (AI), anastrozole (1st Line) – implying both site and agent related efficacy. Absence of significant overall survival (OS) difference in PALOMA 3 (2nd line) has increased the debate regarding when to add CDK 4/6is to ET, especially given the OS advantage for Ful 500 monotherapy in the 1st & 2nd line settings.

Patients & Methods: Anonymised, individual patient level data was obtained from randomised controlled trials (RCTs) involving AI & SERD used as mono-theraphy in 2nd or 3rd Line setting in known HR+ BC. All the trials were Phase 3 double-blind, placebo RCTs. All were rigorously assessed for clinical benefit (CB), progression free survival (PFS), duration of CB (DoCB) and OS. Details of the studies, types of ET and patient numbers are shown in the Table.

Results: Outcome data is presented for each study and then summarised under AI, SERD (Ful 250 or 500) and 'all Ets combined'. Odds ratios (Ors) & hazard ratios (HRs) for VM versus nVM by endocrine agents are shown in the Table.

AgentStudyTotal Pats.HR+ Pats.CBRPFSOSDoCBAI(n)(n)OR (95%Cis)HR (95%Cis)HR (95%Cis)HR (95%Cis)Exe00202301831.181.441.271.50Exe00211931681.151.951.832.12AnaEFECT3403360.941.521.201.10AnaSOFEA2492491.291.181.051.41subtotal7636871.11 (0.84-1.48)1.47*** (1.22-1.79)1.21* (1.01-1.45)1.43** (1.10-1.86)SERDFul 25000202191601.791.701.401.23Ful 25000212041771.281.811.322.06Ful 250EFECT3513450.791.401.311.03Ful 250SOFEA2312310.701.171.242.22Ful 250CONFIRM1521521.131.071.510.84Subtotal9268341.05 (0.75-1.45)1.39*** (1.16-1.67)1.34*** (1.14-1.57)1.36 (0.93-1.98)SERDFul 500CONFIRM1441442.24 (1.12-4.48)1.30 (0.90-1.87)1.33 (1.14-1.57)0.97 (0.55-1.66)All ETsTotal183316651.13 (0.92-1.39)1.42*** (1.26-1.59)1.28*** (1.14-1.44)1.35** (1.09-1.66)

[Pats=Patients; (n)=number; CBR-Clinical Benefit Rate; p-values p<0.05*, p<0.01**, p<0.001***]

Median PFS (months) for nVM for AI, SERD250, SERD500 & ‘all Ets combined’ were 5.4, 5.5, 11.0 & 5.5 respectively: for VM they were 2.9, 3.5, 5.5 & 3.2 respectively.

Median OS (months) for nVM for AI, SERD250, SERD500 & ‘all Ets combined’ was 24.2, 26.0, 35.4 & 25.4 respectively: for VM the figures were 22.8, 20.8, 26.4 & 22.0 respectively.Conclusions:1) In the 2nd line HR+ setting AI & Ful 250 both significantly increased PFS & OS in nVM versus VM. Longer PFS appears due to longer duration of control (DoCB) than increasing the number of patients responding (CBR).

2) Median OS for nVM ranged from 24 – 35 months versus 20.8-26.4 months for VM: for the majority of patients the 2nd line ET setting is not ‘immediately life threating’ and ET is therefore an option to consider.

3) These data on site of disease (nVM vs VM) contribute to the selection of which patients should receive endocrine mono- and which endocrine combination therapy (ie plus mTORi or CDK4/6i) in the second line setting.

Citation Format: Robertson JFR, Di Leo A, Johnston S, Chia S, Bliss J, Bradbury I, Campbell C. Meta-analyses of visceral versus non-visceral metastases treated by AI & SERD agents as 2nd line endocrine therapy (ET) for HR+ breast cancer (BC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-13-13.

Abstract P6-16-01: Health-related quality of life in MONARCH 3: Abemaciclib plus an aromatase inhibitor as initial therapy in women with HR+, HER2- advanced breast cancer

Background: In the MONARCH 3 trial, abemaciclib plus an aromatase inhibitor (AI) significantly improved progression free survival and overall response rate with a generally tolerable safety profile compared to placebo plus AI. Here we report patient-reported outcomes (PRO) including health-related quality of life (Qol), functioning, and symptoms.

Methods: MONARCH 3 was a double-blind, randomized phase III study of abemaciclib or placebo plus an AI in 493 post-menopausal women with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer with no prior systemic therapy in the advanced setting. Two European Organization for Research and Treatment of Cancer (EORTC) questionnaires were included: Quality of Life Questionnaire (QLQ)-Core 30 (C30) and the EORTC QLQ-Breast 23 (BR23) that were assessed at baseline, every 2 cycles through cycle 19, then every 3 cycles until treatment discontinuation, and at short-term follow up. Higher scores on functional and health status/QoL outcomes indicate higher/better levels of functioning or health; conversely higher scores on symptom outcomes indicate higher/worse levels of symptom burden. Between-arm comparisons of change from baseline were conducted using mixed model methods. Statistical significance was set at 0.05 and clinical meaningfulness was set at ≥10 points on a 0-100 scale1.

Results: PRO completion rates were >91% through cycle 19; duration of treatment was longer for abemaciclib plus AI patients (median number of cycles 19 vs.15). Compared to the placebo arm, diarrhea PRO scores in the abemaciclib arm showed a clinically (18.68 points) and statistically significant (p<0.001) increase/worsening. By-cycle analysis showed group mean diarrhea scores returned to near-baseline levels post-therapy. Other symptom PROs showed statistically significant (<0.05) but not clinically meaningful differences; fatigue (4.96; p=0.004), systemic therapy side effects (4.48, p<0.001), appetite loss (4.03; p=0.034), and nausea/vomiting (2.77; p=0.013). These results were consistent with the investigator-reported treatment emergent adverse events (TEAEs). Several non-symptom results were also statistically significant but not clinically meaningful including global health/health status (-4.36; p=0.003), role function (-4.25; p=0.025), social function (-3.41, p=0.047), and body image (-5.11, p=0.009). No statistically significant between-treatment differences were observed for physical, emotional, and cognitive functioning or for symptoms of pain, dyspnea, insomnia, constipation, or financial difficulties.

Conclusions: The addition of abemaciclib to an AI resulted in clinically and statistically significant changes in diarrhea without clinically meaningful differences in other symptom scores. Increased GI-related symptoms were consistent with the manageable, reversible AE profile; the highest symptom burden was reported during early visits. No clinically meaningful differences in global health status or functional scores were observed.

ClinicalTrials.gov: NCT02246621

Reference:

1. Osoba D et al. J Clin Oncol 2002;20(14):3106-13.

Citation Format: Goetz MP, Johnston S, Martin M, Tokunaga E, Park IH, Huober J, Toi M, Price GL, Boye M, Li L, Forrester T, Gainford C, Gable J, Carter GC, Sood A, DiLeo A. Health-related quality of life in MONARCH 3: Abemaciclib plus an aromatase inhibitor as initial therapy in women with HR+, HER2- advanced breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-16-01.

Abstract P4-01-01: Molecular residual disease detection with circulating tumor DNA analysis predicts relapse in patients with early stage breast cancer

Background. Detection of circulating tumor DNA (ctDNA) after treatment of early stage breast cancer may identify molecular residual disease. In a prior proof-of-principle study we demonstrated that detection of ctDNA predicted relapse with high accuracy (Garcia-Murillas et al Science Trans Med 2015). We conducted an independent, prospective, multi-centre validation study.

Methods. In this validation study, a cohort of 170 early stage breast cancer patients were recruited from five hospitals into two prospective sample collection studies. Patients were scheduled to receive standard chemotherapy, surgery +/- radiotherapy, adjuvant endocrine therapy and HER2 antibodies as appropriate. Plasma samples were collected for ctDNA analysis at baseline, post-surgery, three monthly for the first year of follow-up, and six monthly thereafter and shipped to a central lab for processing. Using previously established criteria, tumor was sequenced to identify somatic mutations that were tracked by digital PCR in DNA extracted from 4mls of plasma at all available time points. Buffy coat DNA was analysed at all time-points to control for clonal haematopoesis of indeterminate potential (CHIP) detection. The primary endpoint was to compare invasive disease free survival between patients with and without detection of ctDNA after treatment. A combined analysis of this validation study, and the prior proof-of-principle study, was also conducted to analyse secondary endpoints.

Results. After tumor sequencing, 101 patients from the validation study had at least one mutation to track. At median 35.5 months follow-up, ctDNA was detected in plasma of 15.8% (16/101) patients. Detection of ctDNA strongly predicted relapse, hazard ratio 24.5 (95% CI 6.5 to 93.2, P<0.001 time-dependent Cox model), and was predictive of relapse in all tumor subtypes.

In the combined analysis (N=144), lead-time between ctDNA detection and relapse was 10.7 months (95% CI 7.7-17.0). Six patients had a clinical relapse that was not detected by ctDNA prior to relapse. These patients had a distinct pattern of oligo-metastatic relapse, 3 patients with brain-only metastases (P=0.0068), 1 ovarian oligo-metastasis and 2 local disease recurrence. The level of ctDNA in baseline plasma, prior to treatment, was associated with tumor subtype, highest in triple negative breast cancer (P=0.0036).

Conclusion. Detection of ctDNA after treatment is associated with a high risk of future relapse in early-stage breast cancer. Prospective studies are required to assess the potential of molecular residual disease detection to guide adjuvant therapy.

Citation Format: Turner N, Garcia-Murillas I, Chopra N, Comino-Mendez I, Beaney M, Tovey H, Cutts R, Swift C, Kriplani D, Afentakis M, Hrebien S, Walsh G, Johnston S, Ring A, Russell S, Evans A, Skene A, Wheatley D, Dowsett M, Smith I. Molecular residual disease detection with circulating tumor DNA analysis predicts relapse in patients with early stage breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-01-01.

Abstract GS3-02: PALLET: A neoadjuvant study to compare the clinical and antiproliferative effects of letrozole with and without palbociclib

Background: CDK4/6 inhibitors, such as palbociclib, are used to treat ER+ metastatic breast cancer in combination with endocrine therapy with trials ongoing in patients with primary disease. No biomarkers exist to identify those who do/do not benefit from added CDK4/6 inhibition. PALLET is an investigator-initiated/led phase II randomized trial collaboration between UK and NSABP investigators evaluating the biological and clinical effects of palbociclib with letrozole combination as neoadjuvant therapy.

Methods: Postmenopausal women with ER+ primary breast cancer and tumors >2.0cm (ultrasound) were randomized to one of 4 treatment groups (3:2:2:2 ratio): Group A: letrozole (2.5mg/d) for 14 weeks; Group B: letrozole for 2 weeks followed by letrozole + palbociclib to 14 weeks; Group C: palbociclib for 2 weeks followed by letrozole + palbociclib to 14 weeks; Group D: letrozole + palbociclib for 14 weeks. Palbociclib was given 125mg/d PO on a 21 days on, 7 days off schedule. Post-14 week treatment was at the discretion of the treating clinician including letrozole until surgery. Core-cut biopsies were taken at baseline, 2 weeks and 14 weeks. Co-primary endpoints for letrozole alone vs palbociclib groups (Group A vs Groups B+C+D) were: (i) change in Ki67 (IHC) between baseline and 14 weeks (log-fold change, Mann-Whitney test); (ii) clinical response (ultrasound) after 14 weeks (4 group, ordinal, Mann-Whitney test). Complete cell-cycle arrest (CCCA) (Ki67≤2.7%) was analyzed using a logistic regression model adjusting for recruitment region. Pre-specified exploratory biomarkers included c-PARP (apoptosis).

Results: 307 patients were recruited between 27 Feb 2015 and 08 Mar 2018; 103 were randomized to letrozole alone and 204 to letrozole + palbociclib. 279 (90.9%) patients were evaluable for 14 week clinical response. Clinical response was not significantly different between letrozole vs letrozole + palbociclib groups [(p=0.20; CR+PR 49.5% (46/93) vs 54.3% (101/186) and PD 5.4% (5/93) vs 3.2% (6/186)] nor was the small proportion of patients with pathological CR (1/87, 1.1% vs 6/180, 3.3%; p=0.43). 190 (61.9%) patients were evaluable for 14 week change in Ki67. The median log-fold change in Ki67 was greater with letrozole + palbociclib vs letrozole alone (-4.1 vs -2.2; p<0.001) corresponding to a geometric mean change of -97.4% vs -88.5%. Similarly, a greater proportion of patients who received letrozole + palbociclib achieved CCCA (90% vs 59%, p<0.001). 146 (47.6%) patients were evaluable for c-PARP and the log-fold change (suppression) was greater with letrozole + palbociclib vs letrozole alone (-0.80 vs -0.42; p=0.003) corresponding to a geometric mean change of -56.8% vs -31.4%. Other biomarkers of response / resistance are being evaluated. A higher proportion of patients had a grade ≥3 toxicity on letrozole + palbociclib than letrozole alone (49.8% vs 17.0%; p<0.001) mainly due to asymptomatic neutropenia.

Conclusion: Adding palbociclib to letrozole markedly enhanced the suppression of malignant cell proliferation as assessed by Ki67 but did not substantially increase the clinical response of primary ER+ breast cancer over a 14-week period. Concurrent reductions in cell death may have reduced the speed of tumor shrinkage.

Citation Format: Dowsett M, Jacobs S, Johnston S, Bliss J, Wheatley D, Holcombe C, Stein R, McIntosh S, Barry P, Dolling D, Snowdon C, Perry S, Batten L, Dodson A, Martins V, Modi A, Cornman C, Puhalla S, Wolmark N, Julian T, Pogue-Geile K, Robidoux A, Provencher L, Boileau JF, Shalaby I, Thirlwell M, Fisher K, Huang Bartlett C, Koehler M, Osborne K, Rimawi M. PALLET: A neoadjuvant study to compare the clinical and antiproliferative effects of letrozole with and without palbociclib [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr GS3-02.

Probing multi-spinon excitations outside of the two-spinon continuum in the antiferromagnetic spin chain cuprate Sr2CuO3

One-dimensional (1D) magnetic insulators have attracted significant interest as a platform for studying quasiparticle fractionalization, quantum criticality, and emergent phenomena. The spin-1/2 Heisenberg chain with antiferromagnetic nearest neighbour interactions is an important reference system; its elementary magnetic excitations are spin-1/2 quasiparticles called spinons that are created in even numbers. However, while the excitation continuum associated with two-spinon states is routinely observed, the study of four-spinon and higher multi-spinon states is an open area of research. Here we show that four-spinon excitations can be accessed directly in Sr2CuO3 using resonant inelastic x-ray scattering (RIXS) in a region of phase space clearly separated from the two-spinon continuum. Our finding is made possible by the fundamental differences in the correlation function probed by RIXS in comparison to other probes. This advance holds promise as a tool in the search for novel quantum states and quantum spin liquids.

Complete excision with narrow margins provides equivalent local control to wider excision in breast conservation for invasive cancer

Background

Society of Surgical Oncology and American Society for Radiation Oncology guidelines define clear margins in breast-conserving therapy (BCT) as 'no ink on tumour', in contrast to the attainment of margins of at least 1 mm widely practised in the UK. The primary aim of this study was to explore clinical, surgical and tumour-related factors associated with local recurrence after BCT, with a secondary aim of assessing the impact of margin re-excision on the risk of local recurrence.

Methods

Patient demographics, surgical details, tumour characteristics and local recurrence were recorded for consecutive women with BCT undergoing surgery between January 1997 and January 2007. Margins were defined as clear (greater than 1 mm), close (less than 1 mm but no ink on tumour), reaches (ink on tumour) and clear after re-excision.

Results

A total of 1045 women of median age 54 (range 18-86) years were studied. Median follow-up was 89 (range 4-196) months. Local recurrence occurred in 52 patients (5·0 per cent). Ink on tumour was associated with local recurrence (hazard ratio (HR) 4·86, 95 per cent c.i. 1·49 to 15·79; P = 0·009). Risk of local recurrence was the same for close and clear margins (HR 1·03, 0·40 to 2·62; P = 0·954). In women with involved margins, re-excision was still associated with an increased local recurrence risk (HR 2·50, 1·32 to 4·72; P = 0·005). Oestrogen receptor negativity increased risk (HR 2·28, 1·28 to 4·06; P = 0·005).

Conclusion

Adequately excised margins, even when under 1 mm, provide equivalent outcomes to wider margins in BCT. Achieving complete excision at primary surgery achieves the lowest rates of local recurrence.

Decoupling Carrier Concentration and Electron-Phonon Coupling in Oxide Heterostructures Observed with Resonant Inelastic X-Ray Scattering

We report the observation of multiple phonon satellite features in ultrathin superlattices of the form nSrIrO_{3}/mSrTiO_{3} using resonant inelastic x-ray scattering (RIXS). As the values of n and m vary, the energy loss spectra show a systematic evolution in the relative intensity of the phonon satellites. Using a closed-form solution for the RIXS cross section, we extract the variation in the electron-phonon coupling strength as a function of n and m. Combined with the negligible carrier doping into the SrTiO_{3} layers, these results indicate that the tuning of the electron-phonon coupling can be effectively decoupled from doping. This work both showcases a feasible method to extract the electron-phonon coupling in superlattices and unveils a potential route for tuning this coupling, which is often associated with superconductivity in SrTiO_{3}-based systems.

Center of Mass Motion of Short-Range Correlated Nucleon Pairs studied via the A(e,e^{'}pp) Reaction

Short-range correlated (SRC) nucleon pairs are a vital part of the nucleus, accounting for almost all nucleons with momentum greater than the Fermi momentum (k_{F}). A fundamental characteristic of SRC pairs is having large relative momenta as compared to k_{F}, and smaller center of mass (c.m.) which indicates a small separation distance between the nucleons in the pair. Determining the c.m. momentum distribution of SRC pairs is essential for understanding their formation process. We report here on the extraction of the c.m. motion of proton-proton (pp) SRC pairs in carbon and, for the first time in heavier and ansymetric nuclei: aluminum, iron, and lead, from measurements of the A(e,e^{'}pp) reaction. We find that the pair c.m. motion for these nuclei can be described by a three-dimensional Gaussian with a narrow width ranging from 140 to 170  MeV/c, approximately consistent with the sum of two mean-field nucleon momenta. Comparison with calculations appears to show that the SRC pairs are formed from mean-field nucleons in specific quantum states.

Computing Resonant Inelastic X-Ray Scattering Spectra Using The Density Matrix Renormalization Group Method

We present a method for computing the resonant inelastic x-ray scattering (RIXS) spectra in one-dimensional systems using the density matrix renormalization group (DMRG) method. By using DMRG to address this problem, we shift the computational bottleneck from the memory requirements associated with exact diagonalization (ED) calculations to the computational time associated with the DMRG algorithm. This approach is then used to obtain RIXS spectra on cluster sizes well beyond state-of-the-art ED techniques. Using this new procedure, we compute the low-energy magnetic excitations observed in Cu L-edge RIXS for the challenging corner shared CuO4 chains, both for large multi-orbital clusters and downfolded t-J chains. We are able to directly compare results obtained from both models defined in clusters with identical momentum resolution. In the strong coupling limit, we find that the downfolded t-J model captures the main features of the magnetic excitations probed by RIXS only after a uniform scaling of the spectra is made.

Demonstration of Single-Barium-Ion Sensitivity for Neutrinoless Double-Beta Decay Using Single-Molecule Fluorescence Imaging

A new method to tag the barium daughter in the double-beta decay of ^{136}Xe is reported. Using the technique of single molecule fluorescent imaging (SMFI), individual barium dication (Ba^{++}) resolution at a transparent scanning surface is demonstrated. A single-step photobleach confirms the single ion interpretation. Individual ions are localized with superresolution (∼2  nm), and detected with a statistical significance of 12.9σ over backgrounds. This lays the foundation for a new and potentially background-free neutrinoless double-beta decay technology, based on SMFI coupled to high pressure xenon gas time projection chambers.

Abstract P5-21-02: Efficacy and safety of abemaciclib in patients with liver metastases in the MONARCH 1, 2, and 3 studies

Background:

Abemaciclib is an oral, selective inhibitor of cyclin-dependent kinases 4 & 6 that is dosed on a twice daily continuous schedule. In patients (pts) with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC), abemaciclib has demonstrated clinical efficacy with a tolerable safety profile when administered as monotherapy in MONARCH 1 (NCT02102490), in combination with fulvestrant in MONARCH 2 (NCT02107703), and in combination with non-steroidal aromatase inhibitors (NSAI) in MONARCH 3 (NCT02246621). Inducing tumor response and delaying disease progression is of critical need in pts with liver metastases (mets).

Methods:

An exploratory subgroup analysis was conducted in pts with liver mets at baseline across the MONARCH 1, 2, and 3 studies. All pts had HR+, HER2- ABC. The primary endpoint of MONARCH 1 was objective response rate (ORR), and the primary endpoint of MONARCH 2 and 3 was investigator-assessed progression-free survival (PFS). Analysis methods for these endpoints were previously described. Key enrollment criteria and dosing information are listed in Table 1.

Table 1. Eligibility criteria and dosing information for the MONARCH 1, 2, and 3 studiesKey enrollment criteriaMONARCH 1MONARCH 2MONARCH 3Prior endocrine therapyProgressed on or after ETProgressed while receiving adjuvant or first-line ET, or ≤ 12 months from the end of adjuvant ETET naïve or disease relapse >12 months after (neo)adjuvant ETChemotherapy regimens in advanced setting1 or 200Visceral crisisNo restrictionNot permittedNot permittedDose and Schedule   abemaciclib200 mg, twice daily, continuous150 mg1, twice daily, continuous150 mg, twice daily, continuousfulvestrant-500 mg, per label-anastrozole2--1 mg, dailyletrozole2--2.5 mg, daily1post-amendment; 2physician's choice of NSAI (anastrozole or letrozole); ET: endocrine therapy

Results:

Efficacy results of pts with liver mets are described in Table 2. The most frequent adverse events observed in pts with liver mets in MONARCH 1 were diarrhea, nausea, and fatigue and in the abemaciclib arms of MONARCH 2 and 3 were diarrhea, neutropenia, and nausea.

Table 2. PFS and response rates of pts with liver mets in MONARCH 1, 2, and 3 MONARCH 1MONARCH 2 abemaciclib armMONARCH 2 placebo armMONARCH 3 abemaciclib armMONARCH 3 placebo armPts with liver mets, n93115594830PFS, HR (95% CI)N/A.45 (.31, .64).47 (.25, .87)Median PFS, months5.611.63.115.07.2ORR, n (%)20 (21.5)54 (47.0)9 (15.3)26 (54.2)6 (20.0)CBR, n (%)39 (41.9)77 (67.0)21 (35.6)32 (66.7)12 (40.0)CBR: clinical benefit rate (complete response [CR] + partial response [PR] + stable disease ≥6 months); HR: hazard ratio; ORR: objective response rate (CR+PR); PFS: progression-free survival; pts: patients

Conclusions:

The results suggest that the combination of abemaciclib and endocrine therapy was an effective treatment option in pts with liver metastases, a population deriving modest benefit from single-agent endocrine therapy. Tolerability results were generally consistent with the safety populations previously reported for each study.

Citation Format: Di Leo A, Dickler M, Sledge GW, Toi M, Forrester T, Nanda S, Koustenis A, Bourayou N, Johnston S. Efficacy and safety of abemaciclib in patients with liver metastases in the MONARCH 1, 2, and 3 studies [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-21-02.

Abstract P5-19-01: Impact of palbociclib plus letrozole on patient-reported general health status compared with letrozole alone in ER+/HER2- advanced/metastatic breast cancer

BACKGROUND: Palbociclib plus letrozole significantly improved progression-free survival (PFS) compared with letrozole plus placebo in treatment-naive postmenopausal patients with estrogen receptor-positive (ER+), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC) in the phase 3 PALOMA-2 trial. Here, we compare patient-reported general health status with extended (max 53 cycles) follow-up (data cut off May31st, 2017) (Pfizer: NCT01740427).

METHODS: PALOMA-2 randomized patients 2:1 to palbociclib + letrozole (n=444) or placebo + letrozole (n=222). Patient-reported outcomes were assessed at baseline, day 1 of cycles 1, 2, and 3, and day 1 of every other cycle from cycle 5 until the end of treatment using the EuroQol 5-Dimension Questionnaire (EQ-5D). The EQ-5D is a standardized measure of health status that consists of a descriptive system comprising the following 5 dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression rated at 3 levels (no, some, or extreme problems) and a single index score for health status (ranges generally from 0 [dead] to 1 [full health]) calculated using a standard algorithm. In addition, a visual analog scale (VAS) measured self-rated health status from 0 (worst imaginable) to 100 (best imaginable). Repeated measures mixed-effects analyses were performed to compare overall index and VAS scores between treatments, controlling for baseline.

RESULTS: Completion rates at baseline were >95% in each group. The mean (SD) scores at baseline were comparable between palbociclib plus letrozole and letrozole alone for the VAS (71.3 [21.2] vs 72.3 [19.8]) and the EQ-5D index scores (0.70 [0.25]) vs (0.73 [0.21]). Median follow up was 38 months for palbociclib plus letrozole and 37 months for letrozole only. No statistically significant difference in overall change from baseline in general health status was observed between the treatment arms. The proportion of patients reporting the presence of a problem at baseline was similar for palbociclib plus letrozole and letrozole, respectively: mobility (39% vs 39%), self-care (12% vs 12%), usual activities (44% vs 39%), pain (69% vs 65%), and anxiety/depression (54% vs 54%). No statistically significant difference in overall mean EQ-5D index scores (0.73 vs. 0.71) was observed between the treatment arms.

CONCLUSION: Addition of palbociclib to letrozole maintained general health status and EQ-5D index scores in ER+ HER2- advanced/metastatic breast cancer with no statistically significant differences observed compared to letrozole alone.

Citation Format: Harbeck N, Dieras V, Finn R, Gelmon KA, Walshe JM, Shparyk Y, Mori A, Lui DR, Bhattacharyya H, Iyer S, Johnston S, Rugo HS. Impact of palbociclib plus letrozole on patient-reported general health status compared with letrozole alone in ER+/HER2- advanced/metastatic breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-19-01.

Abstract OT3-05-05: MonarchE: A randomized, open-label, phase 3 study of abemaciclib combined with standard adjuvant endocrine therapy versus standard adjuvant endocrine therapy alone in patients with high risk, node positive, early stage, HR+, HER2- breast cancer

Background: Abemaciclib, an oral, selective inhibitor of cyclin-dependent kinases 4 and 6 dosed on a twice daily continuous schedule, has demonstrated clinical efficacy and tolerability in patients (pts) with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer when administered as monotherapy (MONARCH 1) and in combination with endocrine therapy (ET) in MONARCH 2 and MONARCH 3. In neoMONARCH, abemaciclib plus anastrozole as neoadjuvant therapy reduced the breast tumor cell proliferation marker Ki67 to a greater extent than anastrozole alone after 2 weeks of treatment. Endocrine monotherapy is the current standard of care in the adjuvant setting. However, a proportion of pts relapse despite this therapy. A population with a higher risk of recurrence (15% at 5 years) may be identified based on the clinical and pathological characteristics of disease. Optimizing adjuvant therapy for these pts is an important need.

Trial Design: MonarchE (NCT03155997) is a multicenter, randomized, open-label Phase 3 trial that will evaluate the potential for abemaciclib to enhance adjuvant ET. Pts will be randomized 1:1 to abemaciclib 150 mg twice daily continuous schedule plus standard of care (SOC) adjuvant ET versus SOC adjuvant ET alone and stratified by prior chemotherapy (neoadjuvant, adjuvant, or none), menopausal status (pre- or post-), and region (N. America/Europe, Asia, or other). Pts may have started ET within 8 weeks prior to randomization. Pts will receive abemaciclib for up to 2 years in combination with ET per physician's choice (such as tamoxifen or an aromatase inhibitor, +/- ovarian suppression). ET alone will be continued as clinically indicated. All randomized pts will be followed for a total of 10 years.

Eligibility Criteria: Eligible pts (male or female) must have early stage resected HR+, HER2- invasive breast cancer with either ≥ 4 positive pathological axillary lymph nodes (pALNs), or 1 to 3 positive pALNs and at least one of the following high risk markers: primary tumor size ≥5 cm, histological grade 3 tumor, or centrally assessed Ki67 index of ≥20% (in a subset of pts). Pts must have completed definitive locoregional therapy (+/- (neo)adjuvant chemotherapy) and be randomized no more than 12 weeks after completion of last non-ET (surgery, chemotherapy, or radiotherapy). Pts must have tumor tissue available for biomarker analysis prior to randomization.

Specific Aims: The primary objective of monarchE is to evaluate invasive disease-free survival (IDFS) per the STEEP System.1 Secondary objectives include evaluation of IDFS in pts with Ki67 index of ≥20%, distant relapse-free survival, overall survival, safety, pharmacokinetics, and pt health outcomes.

Statistical Methods: Assuming an IDFS hazard ratio of .73, the study is powered to approximately 80% to test the superiority of abemaciclib plus standard ET at a 1-sided α=0.025 using a stratified log-rank test.

Target accrual: Approximately 3580 pts

Contact information: 1-877-285-4559

Reference:

1. Hudis et al. J Clin Oncol. 2007;25(15):2127-2132.

Citation Format: Rastogi P, Toi M, Harbeck N, Bourayou N, Frenzel M, Johnston S. MonarchE: A randomized, open-label, phase 3 study of abemaciclib combined with standard adjuvant endocrine therapy versus standard adjuvant endocrine therapy alone in patients with high risk, node positive, early stage, HR+, HER2- breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT3-05-05.

Abstract P2-02-17: Circulating tumor DNA analysis with ultra-high sensitivity sequencing in metastatic breast cancer

Introduction.

Circulating tumor DNA analysis has the potential to transform the clinical management of patients with breast cancer. We assessed the accuracy of ultra-high sensitivity ctDNA testing in patients with advanced breast cancer.

Methods.

From a prospective tissue collection study, we identified 25 patients with a contemporaneous metastatic tissue biopsy and plasma for ctDNA testing. Tumour DNA from the metastatic tissue biopsy was sequenced with a validated clinical hybrid capture panel, while plasma cell free DNA was sequenced with AVENIO ctDNA technology – a molecular barcoded duplex sequencing based on CAPPseq technology. Sample collection is on-going and results from the full concordance series will be presented at the conference.

Results.

Circulating tumour DNA was detectable in 87% (20/23) of patients, with at least one variant from tissue sequencing identified in plasma. There was overall high agreement between tissue and plasma sequencing. The sensitivity of plasma testing for variants identified in tumour, positive percent agreement, was 75% (24/32). Plasma testing revealed a diversity of sub-clonal mutations including polyclonal ESR1, polyclonal FGFR2 and FGFR3 mutations, rare KRAS mutations, and TSC1 and MSH2 inactivating mutations.

Conclusions.

Circulating tumour DNA testing with molecular barcoded duplex sequencing offers high sensitivity for tumour variant detection. The extent of sub-clonal resistance mutations identified emphasises the genetic diversity of advanced breast cancer.

Citation Format: Garcia-Murillas I, Proszek P, Fribbens C, Yuan L, Bye H, Hubank M, Jiang J, Yuang S, Palma J, Johnston S, Ring A, Turner N. Circulating tumor DNA analysis with ultra-high sensitivity sequencing in metastatic breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-02-17.

Tracking evolution of aromatase inhibitor resistance with circulating tumour DNA analysis in metastatic breast cancer

Background

Selection of resistance mutations may play a major role in the development of endocrine resistance. ESR1 mutations are rare in primary breast cancer but have high prevalence in patients treated with aromatase inhibitors (AI) for advanced breast cancer. We investigated the evolution of genetic resistance to the first-line AI therapy using sequential ctDNA sampling in patients with advanced breast cancer.

Patients and methods

Eighty-three patients on the first-line AI therapy for metastatic breast cancer were enrolled in a prospective study. Plasma samples were collected every 3 months to disease progression and ctDNA analysed by digital droplet PCR and enhanced tagged-amplicon sequencing (eTAm-Seq). Mutations identified in progression samples by sequencing were tracked back through samples before progression to study the evolution of mutations on therapy. The frequency of novel mutations was validated in an independent cohort of available baseline plasma samples in the Study of Faslodex versus Exemestane with or without Arimidex (SoFEA) trial, which enrolled patients with prior sensitivity to AI.

Results

Of the 39 patients who progressed on the first-line AI, 56.4% (22/39) had ESR1 mutations detectable at progression, which were polyclonal in 40.9% (9/22) patients. In serial tracking, ESR1 mutations were detectable median 6.7 months (95% confidence interval 3.7-NA) before clinical progression. Utilising eTAm-Seq ctDNA sequencing of progression plasma, ESR1 mutations were demonstrated to be sub-clonal in 72.2% (13/18) patients. Mutations in RAS genes were identified in 15.4% (6/39) of progressing patients (4 KRAS, 1 HRAS, 1 NRAS). In SoFEA, KRAS mutations were detected in 21.2% (24/113) patients although there was no evidence that KRAS mutation status was prognostic for progression free or overall survival.

Conclusions

Cancers progressing on the first-line AI show high levels of genetic heterogeneity, with frequent sub-clonal mutations. Sub-clonal KRAS mutations are found at high frequency. The genetic diversity of AI resistant cancers may limit subsequent targeted therapy approaches.