Viscoelastic anomaly accompanying anti-crossing behaviour in liquid As2Se3

We investigate the dynamic structure factor of the melt of the well known glass former, As₂Se₃, using inelastic x-ray scattering for temperatures, T, [Formula: see text] K and momentum transfers Q from [Formula: see text] nm^-1. An anomaly was observed at Q  =  2.7 nm^-1 ([Formula: see text] K) with, in the context of a simple model, both an abrupt change in frequency and an increased linewidth reminiscent of an anti-crossing in a solid. Comparison with structural information from reverse Monte Carlo modeling of x-ray diffraction data allows us to associate the disappearance of the anomaly at higher temperatures with a drop in the number of mechanical constraints per atom, n _mc, to [Formula: see text] reminiscent of the threshold applicable for glass formation in rigidity theory. It is inferred that the surprising jump in the dispersion in the liquid may be correlated with a stiffness transition in a network glass.

Abstract P5-21-32: AZD5363 in combination with fulvestrant in AKT1-mutant ER-positive metastatic breast cancer

Background: E17K is the most common activating AKT1 mutation and was shown to be a therapeutic target in this multipart Phase 1 study of AZD5363 (NCT01226316), an oral and selective pan-AKT kinase inhibitor, in patients (pts) with AKT1-mutant (AKT1m) advanced solid tumors. In heavily pretreated AKT1m (E17K) ER+ metastatic breast cancer (MBC) pts, monotherapy achieved an objective response rate (ORR) of 20% and a median progression-free survival of 5.5 months (95% CI, 2.9−6.9). Suppression of PI3K-AKT signaling results in induction of ER-dependent transcription, potentially limiting the response to single-agent PI3K/AKT inhibitors. We explored the hypothesis that simultaneous inhibition of AKT and ER signaling would enhance antitumor efficacy in AKT1m ER+ MBC.

Methods: In an expansion of this study, we administered oral AZD5363 400 mg twice daily, 4 days on 3 days off, and fulvestrant 500 mg, to AKT1m (detected in tumor tissue by local screening and/or plasma BEAMing) ER+ HER2– MBC pts, enrolled into a fulvestrant-naïve (FN) or fulvestrant-resistant (FR) cohort (max 24 pts/cohort). Key objectives included safety and efficacy by RECIST v1.1. We report results of a planned interim analysis conducted when 12 pts/cohort reached maturity for assessment of 24-week clinical benefit rate (CBR), defined as the percentage of responders plus those with stable disease (SD) ≥24 weeks.Data cut-off occurred in June 2017.

Results: At the time of analysis, 24 AKT1m pts (23 E17K, 1 E40K) had received treatment. FN had more visceral disease (83.3% vs 66.7%) and ER+/PR– status (25% vs 8.3%) than FR. Median number of prior anticancer regimens was 4.5 (range 1–9) and 6 (2–11) in FN and FR, respectively, with more chemotherapy (CT) and less hormone therapy (HT) exposure in FN vs FR [3 (0–5) vs 2 (0–6) and 2 (0–4) vs 4 (2–6) prior CT and HT, respectively]. Prior palbociclib was received by 1 (8.3%) and 4 (33.3%) pts in FN and FR, respectively. Clinical efficacy is detailed below; CBR was 33% and 42% in FN and FR, respectively (Table 1). There was 1 unconfirmed partial response in patients treated with prior palbociclib and 3 SD. At data cut-off, 18 pts had discontinued treatment: progressive disease, n=12; adverse events (AEs), n=2; other reasons, n=4. AEs were observed in all 24 pts, most commonly diarrhea (71%), nausea (63%), vomiting and decreased appetite (29%). Grade ≥3 AEs occurred in 13 (54%) pts, most frequently maculopapular rash (n=3), nausea, hyperglycemia and back pain (all n=2). Dose reduction due to AEs occurred in 3 pts.

Table 1. Clinical efficacy FNFREligible for interim data cut-off, n1212ORR, n (%)2 (17)4 (33)CBR, n (%)4 (33)5 (42)Confirmed response (complete/partial response), n (%)2 (17)4 (33)SD ≥24 weeks, n (%)2 (17)1 (8)

Conclusions: AZD5363 plus fulvestrant is clinically active in AKT1m ER+ MBC pts, including in pts with demonstrated prior resistance to fulvestrant. Comparatively lower efficacy was observed in the FN cohort; factors that may have potentially contributed (eg disease characteristics) will be explored. cfDNA and genomic data will also be presented.

Citation Format: Smyth LM, Oliveira M, Ciruelos E, Tamura K, El-Khoueiry A, Mita A, You B, Renouf DJ, Sablin M-P, Lluch A, Mayer IA, Bando H, Yamashita H, Ambrose H, de Bruin E, Carr TH, Corcoran C, Foxley A, Lindemann JPO, Maudsley R, Pass M, Rutkowski A, Schiavon G, Banerji U, Scaltriti M, Taylor BS, Chandarlapaty S, Baselga J, Hyman DM. AZD5363 in combination with fulvestrant in AKT1-mutant ER-positive 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 P5-21-32.

Abstract P5-21-05: Withdrawn

This abstract was withdrawn by the authors.

Abstract P3-11-06: A phase 1 study of KHK2375 (entinostat) as monotherapy and in combination with exemestane in Japanese patients with hormone receptor-positive, HER2-negative, advanced or recurrent breast cancer

Background: Patients (pts) with hormone receptor-positive (HR+) and non-life threatening advanced or metastatic breast cancer (BC) are usually treated with sequential endocrine therapies. Endocrine therapies are continued until tumor cells acquire resistance to them, following which pts are switched to cytotoxic chemotherapy. Entinostat (ENT) is an oral inhibitor of class I histone deacetylases (HDACs) and is expected to be used for endocrine therapy-resistant pts. The efficacy of ENT in combination with an aromatase inhibitor (AI) for HR+ BC was demonstrated in a previous randomized phase 2 study. Because of the lack of data on safety and pharmacokinetics (PK) in Japanese HR+ BC pts, we performed this dose escalation phase 1 study to investigate the safety of ENT monotherapy and combination therapy with exemestane (EXE) in postmenopausal women with advanced or recurrent HR+ BC. Secondary objectives were to assess PK and efficacy.

Methods: This study was based on a 3+3 dose escalation design. Postmenopausal women with advanced or recurrent HR+ HER2- BC previously treated with nonsteroidal AIs and with ECOG PS 0-1 were enrolled. The dose limiting toxicities (DLT) of ENT monotherapy (3 mg/qw, 5 mg/qw, or 10 mg/q2w) in Cohort 1-3 and those of ENT (5 mg/qw or 3 mg/qw) in combination with EXE 25 mg/qd in Cohort 4-5 were assessed for 7 and 28 days, respectively. Pts continued ENT (3 mg or 5 mg) in combination with EXE even after the DLT observation period until disease progression or discontinuation for other reasons. Adverse events (AEs) were graded per NCI-CTCAE version 4.03. Tumor response was evaluated by RECIST version 1.1 every 8 weeks. ENT concentration was measured intensively. Samples of peripheral blood mononuclear cells (PBMC) were collected to measure protein lysine hyperacetylation and for immune subset analysis. Optional tumor biopsies for biomarker assessment were collected before and during treatment.

Results: Twelve pts were enrolled and three each were assigned to Cohort 1-4 between Nov 2015 and Sept 2016. Neither DLT nor grade 3-5 AE occurred. As no DLT occurred in Cohort 4, Cohort 5 was omitted as originally planned. The drug-related AEs observed in ≥2 pts during the DLT observation period were grade 1-2 hypophosphatemia (1 pt each in Cohort 2, 3, and 4), grade 1 nausea (1 pt in Cohort 3 and 2 pts in Cohort 4), and grade 1-2 platelet count decreased (2 pts in Cohort 4). AUC0-168 increased in a dose proportional manner. As of May 2017, 4 pts continue to receive study treatment, including one treated for more than 18 months. Biomarker data including protein lysine hyperacetylation and immune subset in PBMC and results of paired biopsy samples will be reported.

Conclusions: This study showed the tolerability of the combination therapy of ENT 5 mg with EXE 25 mg in Japanese pts. There were no new safety concerns as compared to those reported previously. Following this result, a randomized phase 2 study for Japanese pts is planned.

Clinical trial information : NCT02623751.

Citation Format: Shimomura A, Masuda N, Tamura K, Yasojima H, Sawaki M, Nishimura Y, Saji S, Iwata H. A phase 1 study of KHK2375 (entinostat) as monotherapy and in combination with exemestane in Japanese patients with hormone receptor-positive, HER2-negative, advanced or recurrent 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 P3-11-06.