Control of acute myeloid leukemia and generation of immune memory in vivo using AMV564, a bivalent bispecific CD33 x CD3 T cell engager

Off-the-shelf immunotherapeutics that suppress tumor growth and provide durable protection against relapse could enhance cancer treatment. We report preclinical studies on a CD33 x CD3 bivalent bispecific diabody, AMV564, that not only suppresses tumor growth, but also facilitates memory responses in a mouse model of acute myelogenous leukemia (AML). Mechanistically, a single 5-day treatment with AMV564 seems to reduce tumor burden by redirection of T cells, providing a time window for allogeneic or other T cells that innately recognize tumor antigens to become activated and proliferate. When the concentration of bispecific becomes negligible, the effector: target ratio has also shifted, and these activated T cells mediate long-term tumor control. To test the efficacy of AMV564 in vivo, we generated a CD33+ MOLM13CG bioluminescent human cell line and optimized conditions needed to control these cells for 62 days in vivo in NSG mice. Of note, not only did MOLM13CG become undetectable by bioluminescence imaging in response to infusion of human T cells plus AMV564, but also NSG mice that had cleared the tumor also resisted rechallenge with MOLM13CG in spite of no additional AMV564 treatment. In these mice, we identified effector and effector memory human CD4+ and CD8+ T cells in the peripheral blood immediately prior to rechallenge that expanded significantly during the subsequent 18 days. In addition to the anti-tumor effects of AMV564 on the clearance of MOLM13CG cells in vivo, similar effects were seen when primary CD33+ human AML cells were engrafted in NSG mice even when the human T cells made up only 2% of the peripheral blood cells and AML cells made up 98%. These studies suggest that AMV564 is a novel and effective bispecific diabody for the targeting of CD33+ AML that may provide long-term survival advantages in the clinic.

Endocrine-Sensitive Disease Rate in Postmenopausal Patients With Estrogen Receptor-Rich/ERBB2-Negative Breast Cancer Receiving Neoadjuvant Anastrozole, Fulvestrant, or Their Combination: A Phase 3 Randomized Clinical Trial

Importance

Adding fulvestrant to anastrozole (A+F) improved survival in postmenopausal women with advanced estrogen receptor (ER)-positive/ERBB2 (formerly HER2)-negative breast cancer. However, the combination has not been tested in early-stage disease.

Objective

To determine whether neoadjuvant fulvestrant or A+F increases the rate of pathologic complete response or ypT1-2N0/N1mic/Ki67 2.7% or less residual disease (referred to as endocrine-sensitive disease) over anastrozole alone.

Design, Setting, and Participants

A phase 3 randomized clinical trial assessing differences in clinical and correlative outcomes between each of the fulvestrant-containing arms and the anastrozole arm. Postmenopausal women with clinical stage II to III, ER-rich (Allred score 6-8 or >66%)/ERBB2-negative breast cancer were included. All analyses were based on data frozen on March 2, 2023.

Interventions

Patients received anastrozole, fulvestrant, or a combination for 6 months preoperatively. Tumor Ki67 was assessed at week 4 and optionally at week 12, and if greater than 10% at either time point, the patient switched to neoadjuvant chemotherapy or immediate surgery.

Main Outcomes and Measures

The primary outcome was the endocrine-sensitive disease rate (ESDR). A secondary outcome was the percentage change in Ki67 after 4 weeks of neoadjuvant endocrine therapy (NET) (week 4 Ki67 suppression).

Results

Between February 2014 and November 2018, 1362 female patients (mean [SD] age, 65.0 [8.2] years) were enrolled. Among the 1298 evaluable patients, ESDRs were 18.7% (95% CI, 15.1%-22.7%), 22.8% (95% CI, 18.9%-27.1%), and 20.5% (95% CI, 16.8%-24.6%) with anastrozole, fulvestrant, and A+F, respectively. Compared to anastrozole, neither fulvestrant-containing regimen significantly improved ESDR or week 4 Ki67 suppression. The rate of week 4 or week 12 Ki67 greater than 10% was 25.1%, 24.2%, and 15.7% with anastrozole, fulvestrant, and A+F, respectively. Pathologic complete response/residual cancer burden class I occurred in 8 of 167 patients and 17 of 167 patients, respectively (15.0%; 95% CI, 9.9%-21.3%), after switching to neoadjuvant chemotherapy due to week 4 or week 12 Ki67 greater than 10%. PAM50 subtyping derived from RNA sequencing of baseline biopsies available for 753 patients (58%) identified 394 luminal A, 304 luminal B, and 55 nonluminal tumors. A+F led to a greater week 4 Ki67 suppression than anastrozole alone in luminal B tumors (median [IQR], -90.4% [-95.2 to -81.9%] vs -76.7% [-89.0 to -55.6%]; P < .001), but not luminal A tumors. Thirty-six nonluminal tumors (65.5%) had a week 4 or week 12 Ki67 greater than 10%.

Conclusions and Relevance

In this randomized clinical trial, neither fulvestrant nor A+F significantly improved the 6-month ESDR over anastrozole in ER-rich/ERBB2-negative breast cancer. Aromatase inhibition remains the standard-of-care NET. Differential NET response by PAM50 subtype in exploratory analyses warrants further investigation.

Trial Registration

ClinicalTrials.gov Identifier: NCT01953588.

S100A9 upregulated by IFNGR signaling blockade functions as a novel GVHD suppressor without compromising GVL in mice

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative treatment for both malignant and nonmalignant hematologic disorders. However, graft-versus-host disease (GVHD) and malignant relapse limit its therapeutic success. We previously demonstrated that the blockade of interferon-gamma receptor (IFNGR) signaling in donor T cells resulted in a reduction in GVHD while preserving graft-versus-leukemia (GVL) effects. However, the underlying molecular mechanisms remain inconclusive. In this study, we found that S100A9 is a novel GVHD suppressor upregulated when IFNGR is blocked in T cells. Both Ifngr1-/- and S100a9-overexpressing T cells significantly reduced GVHD without compromising GVL, altering donor T-cell trafficking to GVHD target organs in our mouse model of allo-HSCT. In addition, in vivo administration of recombinant murine S100A9 proteins prolongs the overall survival of recipient mice. Furthermore, in vivo administration of anti-human IFNGRα neutralizing antibody (αhGR-Nab) significantly upregulates the expression of S100A9 in human T cells and improved GVHD in our mouse model of xenogeneic human peripheral blood mononuclear cell transplantation. Consistent with S100a9-overexpressing T cells in our allo-HSCT model, αhGR-Nab reduced human T-cell trafficking to the GVHD target organs. Taken together, S100A9, a downstream molecule suppressed by IFNGR signaling, functions as a novel GVHD suppressor without compromising GVL.

Best Practices in CD30 Immunohistochemistry Testing, Interpretation, and Reporting: An Expert Panel Consensus

CONTEXT.—

Although CD30 testing is an established tool in the diagnostic workup of lymphomas, it is also emerging as a predictive biomarker that informs treatment. The current definition of CD30 positivity by immunohistochemistry is descriptive and based on reactivity in lymphomas that are defined by their universal strong expression of CD30, rather than any established threshold. Challenges include inconsistencies with preanalytic variables, tissue processing, pathologist readout, and with the pathologist and oncologist interpretation of reported results.

OBJECTIVE.—

To develop and propose general best practice recommendations for reporting CD30 expression by immunohistochemistry in lymphoma biopsies to harmonize practices across institutions and facilitate assessment of its significance in clinical decision-making.

DESIGN.—

Following literature review and group discussion, the panel of 14 academic hematopathologists and 2 clinical/academic hematologists/oncologists divided into 3 working groups. Each working group was tasked with assessing CD30 testing by immunohistochemistry, CD30 expression readout, or CD30 expression interpretation.

RESULTS.—

Panel recommendations were reviewed and discussed. An online survey was conducted to confirm the consensus recommendations.

CONCLUSIONS.—

CD30 immunohistochemistry is required for all patients in whom classic Hodgkin lymphoma and any lymphoma within the spectrum of peripheral T-cell lymphoma are differential diagnostic considerations. The panel reinforced and summarized that immunohistochemistry is the preferred methodology and any degree of CD30 expression should be reported. For diagnostic purposes, the interpretation of CD30 expression should follow published guidelines. To inform therapeutic decisions, report estimated percent positive expression in tumor cells (or total cells where applicable) and record descriptively if nontumor cells are positive.

Abstract CT026: The effect of intrinsic subtype on inhibition of tumor growth by anastrozole vs. fulvestrant vs. the combination: Results from the Alliance neoadjuvant endocrine therapy (NET) ALTERNATE trial

Introduction: The ALTERNATE trial randomized postmenopausal women with ER Allred 6-8 HER2- breast cancer to 6 months of NET with anastrozole (A), fulvestrant (F) or the combination (A+F). Biopsies were taken preNET and after 4-weeks(wks). Patients with Ki67 values &gt;10% at 4-wks were offered triage to neoadjuvant chemotherapy. Patients with on-treatment Ki67 ≤ 10% who completed NET underwent surgery and Ki67 was reassessed. The primary endpoint was endocrine-sensitive disease rate (ESDR). ESD is defined as pCR or PEPI-0 residual disease (pT1-2, pN0, Ki67 ≤ 2.7%). We previously reported that the ESDR difference between the F-containing arms and the A arm was not &gt;10% (ASCO 2020) and that baseline RNA-seq-based intrinsic subtypes predicted outcomes overall (SABCS 2021). Herein we describe relationships between PAM50 intrinsic subtype and Ki67 values by treatment arm because comparative drug effectiveness in adjuvant endocrine therapy studies in ER+ HER2- breast cancer can be predicted by the degree of Ki67 suppression (PMC3518447).

Methods: 743 of the 1297 eligible patients (A: 264; F: 231; A+F: 248) had RNA extracted from preNET frozen tumor biopsies with &gt;50% tumor content and subjected to RNA seq. Intrinsic subtypes were then assigned as LumA, LumB, and NonLum (Basal or HER2-E) using open-source PAM50-based informatics. Differences in the proportion with wk4 Ki67 &gt; 10%, % change in wk4 ki67, and surgical CCCA (Ki67 ≤ 2.7%) rate (sxCCCA) between treatments and by intrinsic subtype was assessed using stratified logistic regression, Wilcoxon rank sum test, and Fisher’s exact test, respectively. Analysis of sxCCCA excluded those who failed to complete NET for reasons other than disease progression or early Ki67 &gt;10%.

Results: Amongst the 358 LumA cases there were no significant differences in Ki67-based endpoints between treatments. Among the 292 LumB cases, the wk4 ki67 &gt; 10% rate was lower with A+F (19.4%) than A (43%) (P=0.0002) and was somewhat lower in F (31%) versus A (P=0.076). The % change in wk4 Ki67 in LumB cases, adjusted for baseline Ki67, showed markedly superior suppression for A+F versus A (-90% vs. -77%; P=&lt;0.0001) and versus F (-90% vs. -80%; P=0.0026). Furthermore sxCCCA rates were significantly higher with A+F than A (53% vs. 25% P = &lt;0.0001) and somewhat higher for F (37%) than A (p=0.068), indicating that superior antiproliferative effects for A+F persist after 6 months on therapy. Lack of Ki67 suppression in response to treatment was observed in the majority of 43 NonLum samples regardless of treatment.

Conclusion: The combination of A+F was significantly more effective than either drug alone for the control of LumB breast cancer cell proliferation. This suggests that A+F may be a more effective adjuvant endocrine therapy than A alone in LumB disease. The lower Ki67 suppression with A alone also suggests that poorer outcome in some LumB tumors may be due to insufficient ER targeting rather than ER-independent tumor growth

Support: U10CA180821, U10CA180882, U24CA196171, UG1CA189856, U10CA180868 (NRG), NCI BIQSFP, BCRF, Genentech, AstraZeneca. https://acknowledgments.alliancefound.org. (MJE) CPRIT RR140033, P50-CA186784, P50-CA58223, U01-CA214125, U24-CA210954, Gift from Ralph and Lisa Eads, McNair Scholarship.

ClinicalTrials.gov Identifier: NCT01953588

Citation Format: Matthew J. Ellis, Meenakshi Anurag, Jeremy Hoog, Aranzazu Fernandez-Martinez, Cheng Fan, Richard Gibbs, Souzan Sanati, Kiran Vij, Mark Watson, Travis Dockter, Olwen Hahn, Joseph Guenther, Abigail Caudle, Erica Crouch, Amy Tiersten, Monica Mita, Wajeeha Razaq, Tina J. Hieken, Yang Wang, A. Marilyn Leitch, Gary W. Unzeitig, Eric Winer, Anna Weiss, Kelly Hunt, Ann H. Partridge, Charles M. Perou, Vera Suman, Cynthia X. Ma, Lisa A. Carey. The effect of intrinsic subtype on inhibition of tumor growth by anastrozole vs. fulvestrant vs. the combination: Results from the Alliance neoadjuvant endocrine therapy (NET) ALTERNATE trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT026.

Abstract P5-13-20: Identifying a metabolite signature that correlates with tumor proliferation in early-stage breast cancer patients treated with CDK4/6 inhibitors from matched plasma and serum samples

Background: Cyclin-dependent kinase 4/6 inhibitors (CKD4/6i) have demonstrated clinical utility extending progression-free survival (PFS) and overall survival (OS) for advanced hormone receptor positive and HER2 negative (HR+/HER2-) breast cancer patients. The efficacy in early-stage breast cancer (eBC) is unclear, with conflicting results from adjuvant CDK4/6i trials on invasive disease-free survival. Thus, there is a critical need to identify biomarkers of response (BoR) to determine which, if any, eBC patients could benefit from this treatment. This BoR could also stratify advanced BC patients for likelihood to respond to CDK4/6i. Metabolism is influenced by both genome and environment, and changes in the metabolome can be correlated with drug responsiveness. Thus, metabolite BoRs may serve to identify eBC patients for which CDK4/6i would offer a therapeutic benefit.Methods: Plasma and serum samples from 50 early-stage ER+/HER2- breast cancer patients, treated with neoadjuvant CDK4/6 inhibitor palbociclib (palbo) and aromatase inhibitor (AI) anastrozole on NeoPalAna trial (ClinicalTrials.gov identifier NCT01723774), were collected from treatment-naïve patients (BL) and 3 consecutive time points: anastrozole,1 mg daily for 4 weeks (C1D1), anastrozole plus palbo,125 mg daily, for 15 days (C1D15), and for 4-5 months before surgery (SURG). Metabolites were extracted from all samples via methanol and chloroform precipitation and quantified using an unbiased, non-destructive, nuclear magnetic resonance (NMR)-based profiling platform (Olaris®, Inc., Waltham, MA). Statistical analysis and machine learning was used to identify differential metabolites and generate predictive models. A separate validation set of samples was collected from a subset of patients (N=6) who received an additional cycle of palbo treatment prior to surgery to assess model accuracy. Results: Non-parametric differential expression analysis of BL/C1D1, BL/C1D15, and C1D1/C1D15 identified 53 ,97, and 90 differential NMR resonances in plasma (p&lt;0.05) and 36, 34, and 25 differential NMR resonances in serum (p&lt;0.05), respectively. Based on the proliferative marker Ki67 levels at C1D15, 37 patients were classified as responders (Ki67≤2.7%) and 6 patients as non-responders (Ki67&gt;2.7%). Analysis of the responder (R) and non-responder (NR) groups identified that 13 plasma and 14 serum resonances (21 unique resonances and 6 overlapping) were differentially expressed (p&lt;0.05) at C1D1. Many of the differential resonances could be mapped back to amino acid metabolites including several branched chain amino acids such as leucine, valine, and isoleucine, and positively charged amino acids such as lysine. A Olaris® BoR score was generated using 5 differential resonances that had an AUC of 0.931 (training set) and 100% accuracy when predicting palbo-response in a blinded test set (N=6).Conclusion: The differential metabolites identified from matching plasma and serum samples suggest that, compared to serum, plasma has a better representation of the metabolic changes associated with palbo treatment-response. While comparing samples from R and NR patients, amino acids were found to be consistently altered in both serum and plasma before palbo treatment. In addition, a BoR model based on select metabolites could precisely stratify palbo-response in a blinded dataset. A larger independent validation cohort is ongoing.

Citation Format: Chen Dong, Shana Thomas, Chandrashekhar Honrao, Leonardo O. Rodrigues, Nathalie Tessier, Bo Zhang, Souzan Sanati, Kiran Vij, Brenda J. Ernst, Karen S. Anderson, Mateusz Opyrchal, Foluso Ademuyiwa, Lindsay L. Peterson, Matthew P. Goetz, Donald Northfelt, Elizabeth O'Day, Cynthia Ma. Identifying a metabolite signature that correlates with tumor proliferation in early-stage breast cancer patients treated with CDK4/6 inhibitors from matched plasma and serum samples [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 P5-13-20.

Abstract PD9-03: Pam50 intrinsic subtype and risk of recurrence score (ROR) for the prediction of endocrine (ET) sensitivity and pathologic response to chemotherapy in postmenopausal women with clinical stage II/III estrogen receptor positive (ER+) and HER2 negative (HER2-) breast cancer (BC) in the alternate trial (Alliance A011106)

Background: Neoadjuvant ET (NET) offers an opportunity to assess ET sensitivity for ER+ HER2- BC and potentially to tailor therapy. Ki67 &gt;10% on biopsy after 2-4 weeks (wks) of NET identifies patients (pts) with intrinsic ET resistance; while pathologic complete response (pCR) and modified preoperative endocrine prognostic index of 0 (mPEPI 0: pT1-2N0, Ki67 ≤2.7%) at surgery indicates sensitivity to ET. However, on-NET biopsy is not always acceptable or feasible and delays the ET sensitivity determination. PAM50 ROR score and intrinsic subtypes by tumor RNA profiling are prognostic in pts with early stage ER+ HER2- BC, and predict pCR rates to neoadjuvant chemotherapy (NCT) (PMC2667820). We therefore hypothesized that PAM50 analysis on pre-NET biopsies could predict the likelihood of a) a high on-NET Ki67, b) mPEPI-0 or pCR at surgery and, c) pCR for pts triaged to NCT. Methods: The ALTERNATE trial is a phase III study that randomized postmenopausal pts with clinical stage II/III ER+ (Allred score 6-8) HER2- BC to receive neoadjuvant anastrozole, fulvestrant, or both for 6 months before surgery. Research biopsy was required at pre-NET and wk 4, then optional at wk 12. Pts with Ki67 &gt;10% on biopsy at wk 4 or 12 discontinued NET and were offered NCT. PAM50 intrinsic subtype and ROR-P values were generated from mRNA sequencing (RNASeq) analysis on pre-NET biopsies using open-source informatics (PMC7723687) and evaluated for prediction of on-NET Ki67 &gt;10% at wk 4 or 12, pCR or mPEPI-0 post NET, and pCR post NCT. Results: 749 of 1,297 eligible trial pts were included in the analyses, after excluding 548 pts due to insufficient pre-NET tumor for RNASeq (n=511) or PAM50 normal subtype (n=37). Similar to the entire ALTERNATE population, the rate of Ki67 &gt;10% at wk 4 or 12 was 24.4% (95% CI: 21.4-27.7%) and the rate of mPEPI-0/pCR post NET was 19.8% (95% CI: 17.0-22.8%). There were 393 (52.5%) Lum A, 302 (40.3%) Lum B, and 54 (7.2%) non-Lum (9 Basal, 45 HER2-E) BCs. These included 196 (26.2%) ROR-P low, 354 (47.3%) ROR-P medium and 199 (26.6%) ROR-P high BCs. Both the rates of Ki67 &gt;10% at wk 4 or 12 and mPEPI-0/pCR differed significantly with respect to PAM50 subtype or ROR-P category, such that Lum A or ROR-P low BCs were least likely to have a Ki67 &gt;10% at wk 4 or 12 and most likely to achieve mPEPI-0/pCR (Table).

93 of 168 (55.4%) pts triaged to NCT had RNA-seq results, yielding 26 Lum A, 49 Lum B, 4 Basal and 14 HER2-E, with the pCR rates of 0%, 6.1%, 0%, and 21.4%, respectively. There were 10 ROR-P low, 39 medium, and 44 high tumors, with a pCR rate of 0%, 5.1% and 9.1%, respectively. Conclusion: These data indicate that both baseline ROR-P and intrinsic subtype are predictive of early on-NET Ki67 &gt; 10% and mPEPI 0/pCR at surgery after NET. For pts triaged to NCT based on an early on-NET Ki67 &gt;10%, the HER2-E group had the highest pCR rate (20%) and no pCRs were observed in Lum A. These data may be useful for directing neoadjuvant therapy in postmenopausal pts with ER+ HER2- BC. Support: U10CA180821, U10CA180882, U24CA196171, UG1CA189856, U10CA180868 (NRG), NCI BIQSFP, BCRF, Genentech, AstraZeneca. https://acknowledgments.alliancefound.org. (MJE) CPRIT RR140033, P50CA186784, P50-CA58223, U01 CA214125, U24CA210954, Gift from Ralph and Lisa Eads, McNair Scholarship. Trials.gov Identifier: NCT01953588.

Table 1.Rates of Ki67 &gt;10% and mPEPI-0/pCR post NET by PAM50 subtype and ROR-P categoryKi67 &gt;10% at wk 4 or 12mPEPI 0/pCR post NETPAM50 SubtypenYes, n (%)PnNo, n (%)PLum A37251 (13.7%) 95% CI: 10.4-17.6%&lt;0.0001393104 (26.5%) 95%CI: 22.2-31.1%&lt;0.0001Lum B29394 (32.1%) 95% CI: 26.8-37.8%30243 (14.2%) 95%CI: 10.5-18.7%Non-luminal (Basal and HER2-E)5338 (71.7%) 95%CI: 57.6-83.2%541 (1.9%) 95%CI: 0.05-9.9%ROR-P CategorynYes, n (%)PnNo, n (%)PLow18018 (10.0%) 95%CI: 6.0-15.3%&lt;0.000119660 (30.6%) 95%CI: 24.2-37.6%&lt;0.0001Intermediate34474 (21.5%) 95%CI: 17.3-26.2%35471 (20.1%) 95%CI: 16.0-24.6%High19491 (46.9%) 95%CI: 39.7-54.2%19917 (8.5%) 95%CI: 5.1-13.3%

Citation Format: Cynthia X Ma, Meenakshi Anurag, Travis Dockter, Jeremy Hoog, Aranzazu Fernandez-Martinez, Cheng Fan, Richard Gibbs, Souzan Sanati, Kiran Vij, Mark Watson, Olwen Hahn, Joseph Guenther, Abigail Caudle, Erika Crouch, Amy Tiersten, Monica Mita, Wajeeha Razaq, Tina J Hieken, Yang Wang, A. Marilyn Leitch, Gary W Unzeitig, Anna Weiss, Eric P Winer, Kelly Hunt, Ann H Partridge, Lisa A Carey, Charles M Perou, Matthew J Ellis, Vera Suman. Pam50 intrinsic subtype and risk of recurrence score (ROR) for the prediction of endocrine (ET) sensitivity and pathologic response to chemotherapy in postmenopausal women with clinical stage II/III estrogen receptor positive (ER+) and HER2 negative (HER2-) breast cancer (BC) in the alternate trial (Alliance A011106) [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 PD9-03.

Abstract GS4-05: Neoadjuvant chemotherapy (NCT) response in postmenopausal women with clinical stage II or III estrogen receptor positive (ER+) and HER2 negative (HER2-) breast cancer (BC) resistant to endocrine therapy (ET) in the ALTERNATE trial (Alliance A011106)

Background: Ki67 values &gt;10% 2-4 weeks (wks) after starting neoadjuvant ET (NET) indicates persistent cell proliferation, resistance to ET, and is associated with increased risk of recurrence. The ACOSOG Z1031 trial suggested that these tumors are also relatively chemotherapy (chemo) resistant with a low pathologic complete response (pCR) rate to NCT. The ALTERNATE trial (NCT01953588) is a randomized study of neoadjuvant anastrozole (ANA), fulvestrant (FUL), or ANA + FUL in postmenopausal patients (pt) with newly diagnosed clinical stage II or III ER+ (Allred score 6-8)/HER2- BC. Ki67 &gt;10% at wk 4 or 12 after starting NET triggered triage to NCT of physician choice or weekly paclitaxel. Pts who refused protocol-directed therapy, were not candidates for NCT, or decided to undergo immediate surgery are being followed per protocol. Here we report the rates of pCR and residual cancer burden (RCB) following NCT for pts triaged to NCT due to Ki67 &gt;10% at wk 4 or 12. Results: Of the 1,299 eligible pts randomized to receive ANA, FUL, or ANA + FUL, 286 (22%) had Ki67 &gt;10% at wk 4 or 12. 168 of these 286 pts (58.7%) chose to switch to NCT, 32 went to surgery (11.2%), and 86 discontinued further protocol-directed therapy (30.1%). Among the 168 pts who underwent NCT, the presenting clinical T stages were cT2 (n=113; 67.26%), cT3 (n=47; 27.98%) and cT4 (n=8; 4.76%) and N stages were cN0 (n=82; 48.8%), cN1 (n=75; 44.6%), cN2/3 (n=9; 5.4%) and cNx (n=2; 1.2%). Central ER testing was performed on pre-treatment biopsies and confirmed ER Allred score 6-8 in 155 of 168 (92.2%) pts, with the rest being ER Allred score 4-5 (n=5; 3%), ER- (Allred score 0) (n=2; 1.2%), or not tested (n=6; 3.6%). Most (n=139; 82.7%) were ER+/PR+, while 17.3% (n=29) were ER+/PR-, and tumor grades were G1 (n=10; 6%), G2 (n=99; 58.9%), G3 (n=54; 32.1%), not reported (n=5; 3%). Baseline Ki67 levels prior to NET were &gt;10% in 94% (n=158), ≤10% in 3% (n=5), and not done in 3% (n=5). NCT regimens administered included doxorubicin/cyclophosphamide (AC) followed by paclitaxel (T) (n=60; 35.71%); weekly paclitaxel (n=56; 33.33%), docetaxel/cyclophosphamide (TC) (n=33; 19.65%), other doxorubicin and/or taxane containing regimen (n=17; 10.12%), and cyclophosphamide/methotrexate/fluorouracil (CMF) (n=2; 1.19%). 35 (20.8%) pts did not complete planned course of NCT due to toxicity (n=27) or refusal (n=8). 154 NCT pts underwent surgery (mastectomy in 40.3%, and breast conserving surgery in 59.7%). The path ypT stages were Tis/0 (n=10; 6.5%), T1 (n=62; 40.3%), T2 (n=61; 39.6%), and T3/4 (n=21; 13.6%), and the ypN stages were N0 (n=66; 42.9%), N1 (n=57; 37%), N2/3 (n=30; 19.5%), and Nx (n=1; 0.6%). Among the 168 pts who started on NCT (intent to treat population), there were 8 pCRs (no invasive disease in the breast or lymph nodes) (4.8%; 95% CI: 2.1% to 9.2%). Residual Cancer Burden (RCB) categories include RCB 0 (n=8; 4.8%), RCB 1 (n=15; 8.9%), RCB 2 (n=82; 48.8%), RCB 3 (n=42; 25.0%), and not determined (n=21; 12.5%). Correlations of baseline pt and tumor characteristics with pathology response to NCT will also be presented. Conclusion: In pts with NET-resistant ER+/HER2- BC, salvage NCT is not likely to induce a complete or near complete response. More effective treatments are needed for this high-risk ER+/HER2- pt population. Support: U10CA180821, U10CA180882, U24CA196171, UG1CA189856, U10CA180868 (NRG); NCI BIQSFP, BCRF, Genentech, AstraZeneca. https://acknowledgments.alliancefound.org. Clinical Trials.gov Identifier: NCT01953588

Citation Format: Cynthia X Ma, Vera Suman, A. Marilyn Leitch, Souzan Sanati, Kiran Vij, Gary W Unzeitig, Jeremy Hoog, Mark Watson, Olwen Hahn, Joseph Guenther, Abigail Caudle, Erika Crouch, Horacio Maluf, Amy Tiersten, Monica Mita, Wajeeha Razaq, Tina J Hieken, Yang Wang, Travis Dockter, Jo Anne Zujewski, Anna Weiss, Kelly Hunt, Clifford Hudis, Eric P Winer, Matthew J Ellis, Lisa A Carey, Ann H Partridge. Neoadjuvant chemotherapy (NCT) response in postmenopausal women with clinical stage II or III estrogen receptor positive (ER+) and HER2 negative (HER2-) breast cancer (BC) resistant to endocrine therapy (ET) in the ALTERNATE trial (Alliance A011106) [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 GS4-05.

Abstract PD2-10: Validation of a predictive model for potential response to neoadjuvant endocrine therapy (NET) in postmenopausal women with clinical stage II or III estrogen receptor positive (ER+) and HER2 negative (HER2-) breast cancer (BC): An ALTERNATE trial analysis (Alliance A011106)

Background: NET is offered to postmenopausal patients (pts) with clinical stage 2/3 ER+/HER2- BC to promote breast-conserving surgery. Also limited surgical accessibility during the COVID19 pandemic has increased NET utility. Inability to identify ET-resistant disease at diagnosis risks disease progression (PD) and delays more effective treatments. Dowsett et al. recently demonstrated that baseline levels of ER, progesterone receptor (PR), Ki67 (&gt;15% vs ≤15%), and Ki67 (&gt;10% vs ≤10%) 2-4 weeks (wks) after starting NET may improve appropriate patient (pt) selection for NET (PMC7280290). The ER, PR and Ki67-based prediction model divides pts with primary ER+/HER2- BC into 3 groups for appropriateness for NET: (Group 1) NET is likely to be inappropriate (Allred ER &lt;6 or ER 6 and PgR &lt;6), (Group 2) NET may be appropriate and a biopsy for on-treatment Ki67 analysis may be considered after 2-4 wks of NET (2A: ER 7 or 8 and PgR &lt;6 and 2B: ER 6 or 7 and PgR ≥6) given that on-treatment Ki67 &gt;10% has been associated with worse outcome (PMC5455353), or (Group 3) NET is appropriate (ER 8 and PgR ≥6). The ALTERNATE trial (NCT01953588) randomized postmenopausal women with clinical stage II or III, ER+ (Allred score 6-8)/HER2- BC to receive anastrozole (ANA), fulvestrant (FUL), or ANA + FUL for 6 months, unless Ki67 was &gt;10% on wk 4 or 12 biopsy, in which case pts were triaged to receive neoadjuvant chemotherapy (NCT) or surgery. As previously reported, the ET-sensitive disease (mPEPI 0 plus pCR) rates were similar across the treatment arms and overall 22% (286 of 1,299) pts had Ki67 &gt;10% at wk 4 or 12. The ALTERNATE trial therefore provides a large independent data set to evaluate the NET appropriateness model.

Results: Among 1,299 eligible pts randomized to receive 6 months of NET, 214 were excluded due to absent HR Allred score (n=41) or absence of pre-treatment and wk 4 Ki67 determinations (n=173). The proportions of the remaining 1,085 pts in Group 1, 2 and 3 were 1% (n=10), 43% (n= 468), and 56% (n=607), respectively. On-study Ki67 &gt;10% prompting conversion from NET to NCT/Surgery occurred in: Group 1 90% (9 of 10), Group 2 30% (141 of 468), and Group 3 17% (104 of 607) (Table 1). Among the 1,075 pts in Groups 2 and 3, 260 (24%) pts had Ki67 ≤15% at baseline (BL), among whom only 14 (5.4%) had Ki67 &gt;10% at wk 4, compared to 231 of the 815 (28.3%) who had BL Ki67 &gt;15% and subsequent Ki67 &gt;10% at wk 4. 2% of pts who remained on NET due to on-treatment Ki67 &lt;10% had PD. Response and PEPI-0 rates by group will be reported.

Conclusion: ALTERNATE trial data support a model whereby levels of ER, PR and Ki67 at diagnosis can be used for the identification of postmenopausal pts with primary ER+/HER2- BC who are appropriate for NET. When baseline ER Allred scores are &gt;6 and Ki67 ≤15%, there is a low likelihood of ET-resistant disease. When BL Ki67 is &gt;15%, ET sensitivity is variable, and on-treatment biopsy for Ki67 may assist in triaging regarding NET appropriateness, particularly given the extremely low local PD rates seen in ALTERNATE when on-treatment Ki67 was &lt;10%. Support: U10CA180821, U10CA180882, U24CA196171, UG1CA189856, U10CA180868 (NRG); NCI BIQSFP, BCRF, Genentech, AstraZeneca. https://acknowledgments.alliancefound.org; Clinical Trials.gov Identifier: NCT01953588

Table 1 Baseline levels of ER, PR, and Ki67 in Relation to Wk 4 Ki67 (N=1,085)BaselineWeek 4GroupNERAllred ScorePRAllred ScoreKi67Ki67 ≤10%N (%)Ki67 &gt;10%N (%)1N=26&lt;6≤15%0 (0%)2 (100%)9 (90)N=86&lt;6&gt;15%1 (12.5%)7 (87.5%)2AN=647 or 8&lt;6≤15%61 (95.3%)3 (4.7%)90 (30.1)N=2357 or 8&lt;6&gt;15%148 (63%)87 (37%)2BN=466 or 7≥6≤15%42 (91.3%)4 (8.7%)51 (30.2)N=1236 or 7≥6&gt;15%76 (61.8%)47 (38.2%)3N=1508≥6≤15%143 (95.3%)7 (4.7%)104 (17.1)N=4578≥6&gt;15%360 (78.8%)97 (21.2%)

Citation Format: Matthew J Ellis, Vera Suman, A. Marilyn Leitch, Souzan Sanati, Kiran Vij, Gary W Unzeitig, Jeremy Hoog, Mark Watson, Olwen Hahn, Joseph Guenther, Abigail Caudle, Erika Crouch, Horacio Maluf, Mitch Dowsett, Amy Tiersten, Monica Mita, Wajeeha Razaq, Tina J Hieken, Yang Wang, Travis Dockter, Jo Anne Zujewski, Anna Weiss, Clifford Hudis, Eric P Winer, Kelly Hunt, Ann H Partridge, Cynthia X Ma, Lisa A Carey. Validation of a predictive model for potential response to neoadjuvant endocrine therapy (NET) in postmenopausal women with clinical stage II or III estrogen receptor positive (ER+) and HER2 negative (HER2-) breast cancer (BC): An ALTERNATE trial analysis (Alliance A011106) [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 PD2-10.

Reactivity with the EpCAM-specific antibodies MOC-31 and Ber-Ep4 in plasma cell neoplasms: a potential diagnostic pitfall in cytology samples

OBJECTIVE

Epithelial cell adhesion molecule (EpCAM) is a protein expressed on surfaces of healthy epithelia, and is overexpressed in dysplasias and carcinomas. Immunohistochemistry (IHC) utilizing antibodies that react with EpCAM, such as MOC-31 and Ber-EP4, distinguish reactive mesothelial cells from carcinomas in serous effusions. IHC is crucial in effusions with singly dispersed atypical cells, a scenario with a broad differential, including hematopoietic malignancies. Plasma cell neoplasms (PCN) are the second most common hematopoietic malignancy, manifesting as multiple myeloma or plasmacytoma, with 6% of cases developing serous cavity involvement. Most PCNs are readily recognizable; however, variants that deviate from the classic cytomorphology risk erroneous diagnosis. This study demonstrates EpCAM expression in a subset of PCNs, highlighting a potential diagnostic pitfall in serous effusion cytology.

METHODS

A 10-year retrospective search for cytology specimens with a diagnosis of PCN was performed. All cases demonstrating CD138/CD38 and monoclonal immunoglobulin expression, and adequately cellular cell block were included. IHC analysis for MOC-31 and Ber-EP4 was performed using Ventana Benchmark Ultra. Scoring was performed as follows: total IHC score equals the positive proportion (0 = no positive tumor cells; 1 = <1%; 2 = 1-10%; 3 =11-33%; 4 = 34-66%; 5 = 67-100%) plus staining intensity (0, no staining; 1, weak; 2, moderate; 3, strong). A score > 4 was considered positive.

RESULTS

2 of 28 (7%) PCNs demonstrated positivity for MOC-31 and Ber-Ep4.

CONCLUSION

A subset of PCNs in cytology samples show positivity for MOC-31 and Ber-EP4 which could result in misinterpretation as carcinoma.

Serum thymidine kinase 1 activity as a pharmacodynamic marker of cyclin-dependent kinase 4/6 inhibition in patients with early-stage breast cancer receiving neoadjuvant palbociclib

BACKGROUND

Thymidine kinase 1 (TK1) is a cell cycle-regulated enzyme with peak expression in the S phase during DNA synthesis, and it is an attractive biomarker of cell proliferation. Serum TK1 activity has demonstrated prognostic value in patients with early-stage breast cancer. Because cyclin-dependent kinase 4/6 (CDK4/6) inhibitors prevent G₁/S transition, we hypothesized that serum TK1 could be a biomarker for CDK4/6 inhibitors. We examined the drug-induced change in serum TK1 as well as its correlation with change in tumor Ki-67 levels in patients enrolled in the NeoPalAna trial (ClinicalTrials.gov identifier NCT01723774).

METHODS

Patients with clinical stage II/III estrogen receptor-positive (ER+)/HER2-negative breast cancer enrolled in the NeoPalAna trial received an initial 4 weeks of anastrozole, followed by palbociclib on cycle 1, day 1 (C1D1) for four 28-day cycles, unless C1D15 tumor Ki-67 was > 10%, in which case patients went off study owing to inadequate response. Surgery occurred following 3-5 weeks of washout from the last dose of palbociclib, except in eight patients who received palbociclib (cycle 5) continuously until surgery. Serum TK1 activity was determined at baseline, C1D1, C1D15, and time of surgery, and we found that it was correlated with tumor Ki-67 and TK1 messenger RNA (mRNA) levels.

RESULTS

Despite a significant drop in tumor Ki-67 with anastrozole monotherapy, there was no statistically significant change in TK1 activity. However, a striking reduction in TK1 activity was observed 2 weeks after initiation of palbociclib (C1D15), which then rose significantly with palbociclib washout. At C1D15, TK1 activity was below the detection limit (<20 DiviTum units per liter Du/L) in 92% of patients, indicating a profound effect of palbociclib. There was high concordance, at 89.8% (95% CI: 79.2% - 96.2%), between changes in serum TK1 and tumor Ki-67 in the same direction from C1D1 to C1D15 and from C1D15 to surgery time points. The sensitivity and specificity for the tumor Ki-67-based response by palbociclib-induced decrease in serum TK1 were 94.1% (95% CI 86.2% - 100%) and 84% (95% CI 69.6% -98.4%), respectively. The κ-statistic was 0.76 (p < 0.001) between TK1 and Ki-67, indicating substantial agreement.

CONCLUSIONS

Serum TK1 activity is a promising pharmacodynamic marker of palbociclib in ER+ breast cancer, and its value in predicting response to CDK4/6 inhibitors warrants further investigation.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01723774. Registered on 6 November 2012.

A Phase II Trial of Neoadjuvant MK-2206, an AKT Inhibitor, with Anastrozole in Clinical Stage II or III PIK3CA-Mutant ER-Positive and HER2-Negative Breast Cancer

Purpose: Hyperactivation of AKT is common and associated with endocrine resistance in estrogen receptor-positive (ER⁺) breast cancer. The allosteric pan-AKT inhibitor MK-2206 induced apoptosis in PIK3CA-mutant ER⁺ breast cancer under estrogen-deprived condition in preclinical studies. This neoadjuvant phase II trial was therefore conducted to test the hypothesis that adding MK-2206 to anastrozole induces pathologic complete response (pCR) in PIK3CA mutant ER⁺ breast cancer.Experimental Design: Potential eligible patients with clinical stage II/III ER⁺/HER2^- breast cancer were preregistered and received anastrozole (goserelin if premenopausal) for 28 days in cycle 0 pending tumor PIK3CA sequencing. Patients positive for PIK3CA mutation in the tumor were eligible to start MK-2206 (150 mg orally weekly, with prophylactic prednisone) on cycle 1 day 2 (C1D2) and to receive a maximum of four 28-day cycles of combination therapy before surgery. Serial biopsies were collected at preregistration, C1D1 and C1D17.Results: Fifty-one patients preregistered and 16 of 22 with PIK3CA-mutant tumors received study drug. Three patients went off study due to C1D17 Ki67 >10% (n = 2) and toxicity (n = 1). Thirteen patients completed neoadjuvant therapy followed by surgery. No pCRs were observed. Rash was common. MK-2206 did not further suppress cell proliferation and did not induce apoptosis on C1D17 biopsies. Although AKT phosphorylation was reduced, PRAS40 phosphorylation at C1D17 after MK-2206 persisted. One patient acquired an ESR1 mutation at surgery.Conclusions: MK-2206 is unlikely to add to the efficacy of anastrozole alone in PIK3CA-mutant ER⁺ breast cancer and should not be studied further in the target patient population. Clin Cancer Res; 23(22); 6823-32. ©2017 AACR.

HTLV-1 viral oncogene HBZ induces osteolytic bone disease in transgenic mice

Adult T-cell leukemia/lymphoma (ATL) is an aggressive T cell malignancy that occurs in HTLV-1 infected patients. Most ATL patients develop osteolytic lesions and hypercalcemia of malignancy, causing severe skeletal related complications and reduced overall survival. The HTLV-1 virus encodes 2 viral oncogenes, Tax and HBZ. Tax, a transcriptional activator, is critical to ATL development, and has been implicated in pathologic osteolysis. HBZ, HTLV-1 basic leucine zipper transcription factor, promotes tumor cell proliferation and disrupts Wnt pathway modulators; however, its role in ATL induced osteolytic bone loss is unknown. To determine if HBZ is sufficient for the development of bone loss, we established a transgenic Granzyme B HBZ (Gzmb-HBZ) mouse model. Lymphoproliferative disease including tumors, enlarged spleens and/or abnormal white cell counts developed in two-thirds of Gzmb-HBZ mice at 18 months. HBZ positive cells were detected in tumors, spleen and bone marrow. Importantly, pathologic bone loss and hypercalcemia were present at 18 months. Bone-acting factors were present in serum and RANKL, PTHrP and DKK1, key mediators of hypercalcemia and bone loss, were upregulated in Gzmb-HBZ T cells. These data demonstrate that Gzmb-HBZ mice model ATL bone disease and express factors that are current therapeutic targets for metastatic and bone resident tumors.

Azacitidine Mitigates Graft-versus-Host Disease via Differential Effects on the Proliferation of T Effectors and Natural Regulatory T Cells In Vivo

Azacitidine (AzaC) mitigates graft-versus-host disease (GvHD) in both murine preclinical transplant models and in human clinical trials while maintaining a robust graft-versus-leukemia effect. Previous studies have failed to investigate the role of natural regulatory T cells (nTregs) on the mitigation of GvHD by AzaC, instead focusing on the generation of suppressive Tregs (CD4⁺CD25⁺FOXP3⁺) through the in vivo conversion of alloreactive donor T effectors (Teffs; CD4⁺CD25^-FOXP3^-) and the direct antiproliferative effects of AzaC on allogeneic T cells. Using B6.Foxp3^DTR/GFP mice in which Tregs can be specifically ablated through administration of diphtheria toxin, we demonstrate that natural Tregs are required in the donor graft for AzaC to optimally protect against GvHD and that nTregs, unlike Teffs (CD3⁺FOXP3^-), are resistant to the antiproliferative effects of AzaC. Gene expression analysis identified the potent cell cycle inhibitor, p21, was significantly upregulated in Teffs but not nTregs after treatment with AzaC. Furthermore, we demonstrate that Teffs deficient in p21 are less sensitive to the antiproliferative effects of AzaC. These results demonstrate that nTregs are essential for AzaC to fully protect against GvHD and have important clinical implications for future clinical trials testing AzaC as a novel method of GvHD prophylaxis in man.

NeoPalAna: Neoadjuvant Palbociclib, a Cyclin-Dependent Kinase 4/6 Inhibitor, and Anastrozole for Clinical Stage 2 or 3 Estrogen Receptor-Positive Breast Cancer

Purpose: Cyclin-dependent kinase (CDK) 4/6 drives cell proliferation in estrogen receptor-positive (ER⁺) breast cancer. This single-arm phase II neoadjuvant trial (NeoPalAna) assessed the antiproliferative activity of the CDK4/6 inhibitor palbociclib in primary breast cancer as a prelude to adjuvant studies.Experimental Design: Eligible patients with clinical stage II/III ER⁺/HER2^- breast cancer received anastrozole 1 mg daily for 4 weeks (cycle 0; with goserelin if premenopausal), followed by adding palbociclib (125 mg daily on days 1-21) on cycle 1 day 1 (C1D1) for four 28-day cycles unless C1D15 Ki67 > 10%, in which case patients went off study due to inadequate response. Anastrozole was continued until surgery, which occurred 3 to 5 weeks after palbociclib exposure. Later patients received additional 10 to 12 days of palbociclib (Cycle 5) immediately before surgery. Serial biopsies at baseline, C1D1, C1D15, and surgery were analyzed for Ki67, gene expression, and mutation profiles. The primary endpoint was complete cell cycle arrest (CCCA: central Ki67 ≤ 2.7%).Results: Fifty patients enrolled. The CCCA rate was significantly higher after adding palbociclib to anastrozole (C1D15 87% vs. C1D1 26%, P < 0.001). Palbociclib enhanced cell-cycle control over anastrozole monotherapy regardless of luminal subtype (A vs. B) and PIK3CA status with activity observed across a broad range of clinicopathologic and mutation profiles. Ki67 recovery at surgery following palbociclib washout was suppressed by cycle 5 palbociclib. Resistance was associated with nonluminal subtypes and persistent E2F-target gene expression.Conclusions: Palbociclib is an active antiproliferative agent for early-stage breast cancer resistant to anastrozole; however, prolonged administration may be necessary to maintain its effect. Clin Cancer Res; 23(15); 4055-65. ©2017 AACR.

Abstract P5-04-02: Serum thymidine kinase 1 activity as a pharmacodynamics marker of cyclin-dependent kinase 4/6 inhibition in patients with early stage breast cancer receiving neoadjuvant palbociclib

Background: Thymidine kinase 1 (TK1) is a fundamental enzyme in DNA synthesis. TK1 expression is E2F-dependent and peaks in the S-phase of the cell cycle. In preclinical studies, inhibition of cyclin-dependent kinase (CDK) 4/6 led to dose dependent reduction of TK1 activity in cultured media. We hypothesized that serum TK1 could serve as a non-invasive surrogate marker of cell proliferation in patients (pts) receiving CDK4/6 inhibitors. In this study, we examined serum TK1 activity from breast cancer (BC) pts enrolled on a neoadjuvant study of palbociclib (Palbo) plus anastrozole (A), for changes induced by Palbo, and correlated with changes in tumor Ki67.

Methods: In this phase II neoadjuvant study, 50 pts with clinical stage II or III estrogen receptor positive (ER+) HER2- BC, received A (in combination with goserelin if premenopausal) alone for 28 days in cycle 0 (C0), followed by the addition of Palbo (125 mg daily on days 1-21) on cycle 1 day 1 (C1D1) for 4 28-day cycles (C1 to C4) unless C1D15 tumor Ki67&gt;10%, in which case pts went off study. Following completion of cycle 4, A was continued for another 3-5 weeks to allow Palbo washout prior to surgery, except in 8 pts who received an additional 10-12 days of Palbo immediately prior. Blood and tumor biopsies were collected at 4 time points: baseline, C1D1, C1D15, and surgery. Serum TK1 activity was measured using the highly sensitive Divitum™ assay according to the Divitum™ Instructions for use (Biovica, Sweden). Tumor Ki67 IHC was performed at the Washington University AMP laboratory using the CONFIRM anti-Ki67 rabbit monoclonal antibody (clone 30-9), and pathologist guided image analysis.

Results: There was no statistically significant difference in TK activity between baseline and C1D1 serum samples (Table 1). However, serum TK activity decreased significantly from C1D1 to C1D15 following the addition of Palbo and increased significantly from C1D15 to surgery following Palbo washout (Table 1), indicating a significant effect of Palbo on TK activity. At C1D15, TK activity was below the detection limit of 20 Du/L in 44 of 48 pts, and was at low levels (24, 26, 26, and 58 Du/L) in the remaining 4 pts, indicating a profound effect by Palbo. Interestingly, the TK activities of the 4 pts with tumor Ki67 &gt;10% at C1D15 were all below 20 Du/L, suggesting the possibility of tumor cell proliferation independent of CDK4/6 inhibition.

The sensitivity and specificity of change (increase/decrease) in serum TK activity to predict tumor Ki67 (increase/decrease) induced by Palbo were 83% (19/23, 95%CI: 66-99%) and 93% (26/28, 95%CI: 83%-100%), respectively. The Kappa statistic was 0.761 (P&lt;0.001), indicating substantial agreement between the two tests.

Conclusions: Serum TK1 activity may serve as a pharmacodynamics marker of CDK4/6 inhibition and further investigation is warranted.

Table 1. Serum TK1 and tumor Ki67 Serum TKKi67 Median (IQR) (Du/L)NMedian (IQR) (%)NBaseline46 (25-73)4824.34% (11.92%-35.43%)45Cycle 1 day 143 (27.5-98)495.37% (2.49%-13.59%)*45Cycle 1 day 1520 (20-20)*480.78% (0.23%-1.05%)*45Day of surgery136.0 (37.5-259)*378.33% (2.25%-23.03%)*34*P&lt;0.001 compared to the preceding time point.

Citation Format: Liu N, Thomas S, Luo R, Hoog J, Suh EM, Bergqvist M, Neumüller M, Guo Z, Vij K, Sanati S, Ellis M, Ma C. Serum thymidine kinase 1 activity as a pharmacodynamics marker of cyclin-dependent kinase 4/6 inhibition in patients with early stage breast cancer receiving neoadjuvant palbociclib [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-04-02.

Abstract S6-05: A phase II trial of neoadjuvant palbociclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor, in combination with anastrozole for clinical stage 2 or 3 estrogen receptor positive HER2 negative (ER+HER2-) breast cancer (BC)

Background

ER+ BC is associated with activated CDK4/6. The CDK4/6 inhibitor palbociclib (P) markedly improves time to progression in advanced ER+HER2- BC. We conducted a neoadjuvant phase II trial to determine the activity of P in primary breast cancer as a prelude to adjuvant studies.

Methods

To assess molecular changes induced by anastrozole (A) or P+A, patients (pts) were treated initially with A alone (1mg PO daily) for 28 days in cycle 0 (C0) before the addition of P (125mg PO daily on D1-21 each cycle) on C1D1. P+A was administered for 4 28-day cycles followed by C5 with A alone for 2-4 weeks (wks) before surgery. P was added in C5 for 10-12 days immediately prior to surgery in the last 20 pts enrolled to assess molecular changes induced by A, either alone or in combination with P immediately prior to surgery, in resected tumor. Goserelin was added in premenopausal pts.

Research tumor biopsies were obtained at baseline, C1D1, and C1D15. Central Ki67 analysis was performed at all timepoints, those with Ki67 &gt;10% at C1D15 went off study treatment.

The primary endpoint was complete cell cycle arrest (CCA), defined as Ki67 &lt;2.7%, at C1D15. Patient stratification was based on PIK3CA mutation status with an initial focus on PIK3CA wild type (WT) disease. Pts with PIK3CA mutant (Mut) tumors enrolled to a separate cohort. A sample size of 33 pts in the PIK3CA WT cohort was chosen based on the Fleming's single-stage phase II design to test the hypothesis that P+A leads to &gt; 50% improvement over A in CCA rate on C1D15 biopsy (44% with A alone based on historical data, vs 66% with P+A, power = 0.8, alpha=0.05). The primary endpoint is met if &gt;20 pts achieved CCA in this cohort.

Correlative endpoints included assessment of markers of proliferation, apoptosis, senescence, Rb, gene expression microarray, intrinsic subtype, and next generation sequencing of 83-gene panels, which will be reported at the meeting.

Results

Between 4/23/2013 and 4/24/2015, 50 pts (33 PIK3CA WT, 11 PIK3CA Mut, 2 pending, 4 tissue quantity or quality not sufficient for sequencing (QNS)) were enrolled to the study. Median age was 57.5 (range: 34.1–79.6) years. Four pts, all with WT PIK3CA, went off study due to Ki67 &gt;10% on C1D15 biopsy, 26 pts completed treatment and surgery, 1 refused surgery, 3 withdrew study treatment in C1, and 16 continued to receive study drug (2 in C0, 3 in C1, 4 in C2, 5 in C3, 1 in C4, and 1 in C5). Among the 40 pts currently evaluable for the primary endpoint (C1D15 Ki67), CCA occurred in 34 (85%) pts, including 9 of 9 (100%) PIK3CA Mut, 22 of 28 (78.5%) WT, and 3 of 3 QNS pts. Preliminary analysis of available data indicated a significantly lower Ki67 value after 2 wks of P+A (C1D15) compared to that on A alone (C1D1) (p=0.034, n=18).

Conclusion

This study met the primary endpoint demonstrating that P+A is a highly effective anti-proliferative combination. The sequential biopsy design clearly demonstrated that P+A increased cell cycle control over A alone. P+A was effective regardless of PIK3CA mutation status and these results support the evaluation of this combination in the adjuvant setting for ER+HER2- BC.

Citation Format: Ma CX, Gao F, Northfelt D, Goetz M, Forero A, Naughton M, Ademuyiwa F, Suresh R, Anderson KS, Margenthaler J, Aft R, Hobday T, Moynihan T, Gillanders W, Cyr A, Eberlein TJ, Hieken T, Krontiras H, Hoog J, Han J, Guo Z, Vij K, Mardis E, Al-Kateb H, Sanati S, Ellis MJ. A phase II trial of neoadjuvant palbociclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor, in combination with anastrozole for clinical stage 2 or 3 estrogen receptor positive HER2 negative (ER+HER2-) breast cancer (BC). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr S6-05.

Abstract P5-13-04: A phase II neoadjuvant trial of MK-2206, an AKT inhibitor, in combination with anastrozole for clinical stage 2 or 3 PIK3CA mutant estrogen receptor positive HER2 negative (ER+HER2-) breast cancer (BC)

Background

Activating mutations in PIK3CA occur in approximately 40% ER+BC. MK-2206 (M), a pan-AKT inhibitor, induced apoptosis of ER+ BC under estrogen deprivation in preclinical studies. We conducted this neoadjuvant trial to determine the pathologic complete response (pCR) rate of M plus anastrozole (A) for PIK3CA mutant (Mut) ER+ BC.

Methods

This single arm open label study of M+A used a 2-stage Simon phase II design (stage 1, n=16; stage 2, n=13, alpha=0.10, power=0.90) to test whether pCR rate &lt;1% (based on historical data with A alone), against the alternative that pCR rate ≥15% in PIK3CA Mut ER+ BC. At least 1 pCR in stage 1 was required to proceed to stage 2.

Eligible patients (pts) with clinical stage II or III ER+HER2- BC were pre-registered and proceeded to a research tumor biopsy for PIK3CA sequencing, followed by treatment with daily A monotherapy for 28 days (cycle 0). Pts with PIK3CA Mut BC were subsequently registered, underwent a second biopsy, and started M (150mg PO weekly) with daily A on cycle 1 day 1 (C1D1) for a maximum of four 28-day cycles followed by surgery. Goserelin was added for premenopausal pts. A tumor biopsy on C1D17, 17 days post the start of M, was performed. Those with C1D17 Ki67 &gt;10% discontinued study treatment. pCR was defined as no invasive cancer in the breast and the lymph nodes. Tumor specimens collected at all timepoints are being analyzed for markers of proliferation, apoptosis, and PI3K pathway activity, gene expression microarray, intrinsic subtypes, and next generation sequencing of 83 genes.

Results

Of the 51 pts pre-registered, 35 pts did not register due to no PIK3CA mutation (n=22), inadequate specimen for testing (n=6), physician/pt decision (n=7). The remaining 16 pts (median age: 58, range: 40-77 years) received combination therapy. Three pts did not complete 4 cycles due to C1D17 Ki67 &gt;10% (n=2) and intolerability (grade (Gr) 4 transaminase elevation in C1, n=1). Other severe toxicities possibly related to M included Gr 3 rash (25%) and pruritus (12.5%). Of the 13 pts completed study therapy and underwent surgery, all had residual disease in the breast and 7 also had positive nodes. Table 1 summarized changes in Ki67 during treatment.

ComparisonsnAbsolute changes in Ki67 median (range)Wilcoxon signed rank p-valueC1D1 relative to pre-registration11-17.0% (-49.8 to 4.1%)0.0020C1D17 relative to pre-registration14-16.4% (-51.4 to 4.1%)0.0004C1D17 relative to C1D112-1.5% (-18.6 to 15.8%)0.9697C1D1, biopsy post 28 days of A alone; C1D17 biopsy post 17 days on combination therapy

Although Ki67 levels post A monotherapy (C1D1) or M+A (C1D17) were significantly lower than that of pre-registration samples, Ki67 did not differ between C1D17 and C1D1 samples. Other correlative studies are ongoing and results will be presented.

Conclusion

Despite the small sample size, biomarker analysis on serial biopsy specimens demonstrated that M+A is unlikely to be more effective than A alone in PIK3CA Mut ER+ BC. This trial demonstrated the feasibility of genomic sequencing for pt selection and the value of a small, well-designed proof-of-principle neoadjuvant trial for the evaluation of targeted agents.

Citation Format: Ma CX, Suman VJ, Goetz M, Northfelt D, Burkard M, Ademuyiwa F, Naughton M, Margenthaler J, Aft R, Gray R, Tavaarwerk A, Wilke L, Haddad T, Moynihan T, Loprinzi C, Hieken T, Hoog J, Guo Z, Han J, Vij K, Mardis E, Sanati S, Al-Kateb H, Doyle L, Erlichman C, Ellis MJ. A phase II neoadjuvant trial of MK-2206, an AKT inhibitor, in combination with anastrozole for clinical stage 2 or 3 PIK3CA mutant estrogen receptor positive HER2 negative (ER+HER2-) breast cancer (BC). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-13-04.

Aberrant expression of alpha-fetoprotein in intrahepatic cholangiocarcinoma: an exceptional occurrence

A high level of serum alpha-fetoprotein (AFP) is typically indicative of hepatocellular carcinoma in patients with liver lesions. In this article, we describe an exceptional case of intrahepatic cholangiocarcinoma that occurred in a 36-year-old man with a markedly elevated serum AFP level (12310.7 ng/mL). Histopathologic examination of surgically resected liver mass showed classic morphologic features of cholangiocarcinoma, with no hepatocellular carcinoma component identified. Immunohistochemically, the tumor cells were strongly and diffusely positive for AFP, CA19-9, and cytokeratin 19 and were negative for hepatocyte antigen. The patient's serum AFP level declined to 46.2 ng/mL 1 month after surgery. To the best of our knowledge, this is the first documented case of AFP-producing intrahepatic cholangiocarcinoma with immunohistochemical evidence confirming the tumor cells to be the source of high-level AFP production.

Mice expressing a dominant-negative Ret mutation phenocopy human Hirschsprung disease and delineate a direct role of Ret in spermatogenesis

The Ret receptor tyrosine kinase mediates physiological signals of glial cell line-derived neurotrophic factor (GDNF) family ligands (GFLs) and is essential for postnatal survival in mice. It is implicated in a number of human diseases and developmental abnormalities. Here, we describe our analyses of mice expressing a Ret mutant (RetDN) with diminished kinase activity that inhibits wild-type Ret activity, including its activation of AKT. All RetDN/+ mice died by 1 month of age and had distal intestinal aganglionosis reminiscent of Hirschsprung disease (HSCR) in humans. The RetDN/+ proximal small intestine also had severe hypoganglionosis and reduction in nerve fiber density, suggesting a potential mechanism for the continued gastric dysmotility in postsurgical HSCR patients. Unlike Ret-null mice, which have abnormalities in the parasympathetic and sympathetic nervous systems, the RetDN/+ mice only had defects in the parasympathetic nervous system. A small proportion of RetDN/+ mice had renal agenesis, and the remainder had hypoplastic kidneys and developed tubulocystic abnormalities postnatally. Postnatal analyses of the testes revealed a decreased number of germ cells, degenerating seminiferous tubules,maturation arrest and apoptosis, indicating a crucial role for Ret in early spermatogenesis.

Road-traffic accidents--a demographic and topographic analysis

Injuries and fatalities occur in all forms of transportation, but numerically, road-traffic accidents account for the great majority worldwide. There is little that the autopsy surgeon can contribute to the elucidation of factors leading to the accident as it is largely the circumstantial and forensic laboratory evidence which is likely to reveal a non-accidental cause. However, the doctor's role in detecting the compatibility/incompatibility of the injuries with those usually sustained in traffic accidents (to detect any which are 'atypical', e.g. focal depressed fracture of the skull), distinguishing antemortem from postmortem injuries, demonstrating the presence of any disease capable of creating sudden incapacity and analysing samples for alcohol/drugs, etc., can go a long way in assigning roles to the human and to some extent vehicular and environmental factors. This warrants that a meticulous autopsy be conducted and not merely a catalogue of injuries. It must be appreciated that a fatal accident is likely to result in litigation and the extent of litigation cannot be anticipated at the time of the autopsy. One must, therefore, aim at the close study of any accident victim and a careful assessment of the case is always rewarding. The present study was undertaken in the Department of Forensic Medicine at (a) Government Medical College, Jammu (1991-93), (b) Mulana Azad Medical College, New Delhi (1993-95) and (c) Government Medical College, Chandigarh (1994-June 2000), with the object of doing a comparative analysis of the various aspects of the road-traffic accidents and accidental deaths in three topographically and demographically different cities in India and to suggest remedial measures to bring down the accident rate.

Heart disease vis-à-vis trauma

Virtually all forensic experts deal not only with criminal, suspicious, accidental and suicidal deaths, but are also confronted with a wide range of deaths where a significant natural element is revealed at autopsy. The assaulted victim that dies suddenly or unexpectedly from a stroke during or immediately succeeding the receipt of some non-fatal injuries, or otherwise suffers a clinically unexplained death, can pose far greater difficulties over causation than a gun-shot or a stabbing. This paper presents an analysis of the problem and an approach for determining the cause of death in cases of concurrent trauma with heart disease, and in cases with a substantial natural element of disease but exclusion of trauma. Relevant cases with history, autopsy findings, histopathological findings and toxicological findings are presented in order to illustrate the issue from a practical angle.

Learning-dependent synaptic modifications in the cerebellar cortex of the adult rat persist for at least four weeks

Several experiments have demonstrated increased synapse number within the cerebellar cortex in association with motor skill learning but not with motor activity alone. The persistence of these synaptic changes in the absence of continued training was examined in the present experiment. Adult female rats were randomly allocated to either an acrobatic condition (AC) or a motor activity condition (MC). The AC animals were trained to traverse a complex series of obstacles, and each AC animal was pair-matched with an MC animal that traversed an obstacle-free runway. These animals were further assigned to one of three training conditions. Animals in the EARLY condition were trained for 10 consecutive days before being killed, animals in the DELAY, condition received the same 10 d of training followed by a 28 d period without training, and animals in the CONTINUOUS condition were trained for the entire 38 d. Unbiased stereological techniques were used to obtain estimates of the number of synapses per Purkinje cell within the cerebellar paramedian lobule. Results showed the AC animals to have significantly more synapses per Purkinje cell than the MC animals in all three training conditions. There were no differences in the number of synapses per Purkinje cell among the EARLY, DELAY, and CONTINUOUS conditions. These data demonstrate that both the motor skills and the increases in synapse number presumed to support them persist in the absence of continued training.

Three-dimensional spectral-spatial EPR imaging of free radicals in the heart: a technique for imaging tissue metabolism and oxygenation

It has been hypothesized that free radical metabolism and oxygenation in living organs and tissues such as the heart may vary over the spatially defined tissue structure. In an effort to study these spatially defined differences, we have developed electron paramagnetic resonance imaging instrumentation enabling the performance of three-dimensional spectral-spatial images of free radicals infused into the heart and large vessels. Using this instrumentation, high-quality three-dimensional spectral-spatial images of isolated perfused rat hearts and rabbit aortas are obtained. In the isolated aorta, it is shown that spatially and spectrally accurate images of the vessel lumen and wall could be obtained in this living vascular tissue. In the isolated rat heart, imaging experiments were performed to determine the kinetics of radical clearance at different spatial locations within the heart during myocardial ischemia. The kinetic data show the existence of regional and transmural differences in myocardial free radical clearance. It is further demonstrated that EPR imaging can be used to noninvasively measure spatially localized oxygen concentrations in the heart. Thus, the technique of spectral-spatial EPR imaging is shown to be a powerful tool in providing spatial information regarding the free radical distribution, metabolism, and tissue oxygenation in living biological organs and tissues.