Archetypal Architecture Construction, Patterning, and Scaling Invariance in a 3D Embryoid Body Differentiation Model

Self-organized patterning and architecture construction studying is a priority goal for fundamental developmental and stem cell biology. To study the spatiotemporal patterning of pluripotent stem cells of different origins, we developed a three-dimensional embryoid body (EB) differentiation model quantifying volumetric parameters and investigated how the EB architecture formation, patterning, and scaling depend on the proliferation, cavitation, and differentiation dynamics, external environmental factors, and cell numbers. We identified three similar spatiotemporal patterns in the EB architectures, regardless of cell origin, which constitute the EB archetype and mimick the pre-gastrulation embryonic patterns. We found that the EB patterning depends strongly on cellular positional information, culture media factor/morphogen content, and free diffusion from the external environment and between EB cell layers. However, the EB archetype formation is independent of the EB size and initial cell numbers forming EBs; therefore, it is capable of scaling invariance and patterning regulation. Our findings indicate that the underlying principles of reaction-diffusion and positional information concepts can serve as the basis for EB architecture construction, patterning, and scaling. Thus, the 3D EB differentiation model represents a highly reproducible and reliable platform for experimental and theoretical research on developmental and stem cell biology issues.

Comparative assessment of toxic responses in 3D embryoid body differentiation model and mouse early embryos treated with 5-hydroxytryptophan

Pluripotent stem cells recapitulate in vitro the early developmental stages and are considered promising cell models for predictive developmental toxicity studies. To investigate the consistency between adverse drug effects on early development and the early stages of embryonic stem cell differentiation in three-dimensional (3D) in vitro culture, the toxic responses to 5-hydroxytryptophan (5-HTP; 0.5-2 mM) were evaluated in early mouse embryos and the embryoid body (EB) differentiation model. 3D architectures, developmental and differentiation dynamics and the cell death rates were analyzed in early mouse embryos (E2.5-E5.5) and EBs at 1 and 6 days of differentiation using a combination of confocal immunofluorescence microscopy with high content imaging analysis and quantitative gene expression analysis. Comparative analysis of toxic responses in early embryos and EBs revealed a similar dose- and stage-dependent decrease in the 5-HTP toxic effects during development and differentiation. The integral toxic responses in the early embryos and EBs were significantly dependent on their 3D architecture and cellular composition. Treatment with 5-HTP (1 mM and above) induced developmental arrest, growth inhibition, and increased cell death in the early embryos without the trophoblasts (E2.5) and those with impaired trophoblasts and in early EBs, whereas later embryos and EBs were more resistant due to the protection of the extraembryonic tissues. This study demonstrates that the EB differentiation model is a relevant 3D-model of early mammalian development and can be useful for the predictive evaluation of toxic and teratogenic effects in embryos at the preimplantation and early post-implantation developmental stages.

Immunological predictive and prognostic factors in patients with stage II-III triple negative breast cancer

e12581

Background: Triple negative breast cancer (TNBC) is the most aggressive subtype of breast cancer. Pathologic complete response (pCR) achievement during neoadjuvant chemotherapy (NACT) is very important for these pts as it correlates with long-term outcome. Predictive and prognostic factors for this group of pts are needed. Methods: Since 2014 we treated 98 pts with histologically confirmed stage II-III TNBC with following regimen of NACT: 6 cycles of Cisplatin 75mg/m2 day 1 and Paclitaxel 80mg/m2 days 1, 8, 15, every 4 weeks according to local protocol. After NACT pts proceeded to radical breast surgery with assessing of pathological response. Before the treatment we assessed TILs in biopsy samples of all patients. We also conducted subpopulation analysis of lymphocytes in peripheral blood before treatment. We analyzed CD8+, CD25+, NK and NKT cells as they were reported to be significant earlier. We compared results with median value in reference group (mRG) of healthy women. Results: Among all 98 pts 86 (87%) were operated, pCR was achieved in 60,5% of operated pts. pCR strongly correlated with TILs level: 38,5% for pts with TILs < 5% and 69,8% for pts with TILs > 5% (p = 0,05). We also found that NKT population was associated with pCR: 77,8% vs 45,8% among patients with NKT above mRG and up to mRG, respectively (p = 0,01). It correlated also with tpCR: 22,2% vs 70,6% (p = 0,01). When both CD25+ and NKT population were above mRG pCR rate achieved in 85,7% pts vs 50,0% pts if it was up to mRG (p = 0,049). NK, CD8+ and CD25+ did not show any correlation with pCR. Survival results are presented in table below. NK, NKT and TILs did not show any correlation with survival. Interestingly, CD8+ were also associated with lower incidence of visceral metastases: 42,1% in pts with normal CD8+ and 15,7% in pts with CD8+ above normal (p = 0,19). Conclusions: Not only TILs, but also NKT and CD25+/NKT population in the peripheral blood could be possible predictive factors for patients with stage II-III TNBC receiving NACT. CD8+, CD25+ and NKT populations could be further studied as prognostic markers for this group of patients. [Table: see text]

Abstract P2-16-34: Patterns of survival and efficacy of chemotherapy in elderly patients with triple-negative breast cancer treated in the neoadjuvant setting

Background. Triple negative breast cancer (TNBC) is the most aggressive molecular subtype. It is mostly observed in younger patients, however, substantial proportion of patients are above age of 60. Despite that, this group of patients was not studied and analyzed separately in previous studies.

Objectives. To establish efficacy of neoadjuvant chemotherapy in elderly patients with stage II-III TNBC and patterns of progression for this group of patients.

Methods. Since 2014 we treated 92 patients with histologically confirmed stage II-III TNBC. Neoadjuvant therapy included 6 cycles of Cisplatin 75mg/m2 day 1 and Paclitaxel 80mg/m2 days 1, 8, 15, every 4 weeks according to local protocol. After neoadjuvant chemotherapy patients proceeded to radical breast surgery with assessing pathological response. Then we analyzed clinical characteristics of patients and their survival according to the pathological response achieved.

Results. In our analysis were included 92 patients, 22 of them were elderly patients (above 60). Pathological complete response was achieved in 57,6% of all patients. In the elderly group we observed significantly higher proportion of tumors with advanced stages (N3: 40,9% vs 20,0%, p&lt;0.05, locally advanced: 77,3% vs 51,4%, p&lt;0.05). Although not clinically significant, elderly patients less frequently achieved complete clinical response (28,6% vs 41,4%). Pathologic complete response was achieved in 52,6% of elderly patients and in 71,7% of younger patients (p&lt;0.05). Higher proportion of patients above 60 experienced nephrotoxicity (54,5% vs 17,1%, p&lt;0.05) and peripheral polyneuropathy (22,7% vs 17,1%, p=0.054). In this group of patients only 22,7% completed all 6 cycles as opposed to 65,7% of younger patients (p&lt;0.05). Higher proportion of elderly patients had local recurrence: 45,5% vs 22,9% (p&lt;0.05), visceral metastases: 36,4% vs 17,1% (p&lt;0.05). We observed tendency for this group of patients to have liver and lungs as first sites of metastases (80%), as opposed to younger patients, for whom CNS was the most frequent first metastatic site (50%). To the date of cut-off (June 2019) 17 patients died, all of them due to the progression of the disease (31,8% in elderly group, 14,3% in younger group). Survival outcomes are presented in table below.

Table 1. Survival outcomes.SurvivalBelow 60 y.o.Above 60 y.o.Recurrence-free survival&lt;0.053 years73,7%61,9%5 years69,6%51,6%Survival without distant metastases&lt;0.053 years78,9%68,6%5 years74,6%57,2%Overall survival0,0573 years81,8%72,4%5 years77%54,3%

Conclusion. In our analysis elderly patients with early and locally advanced TNBC demonstrate decreased response, another safety profile and lower survival rates. Different efficacy could be explained with lower number of cycles of neoadjuvant chemotherapy administered and more advanced stages upon presentation. Different metastatic patterns which we observed in younger and elderly patients should be further studied.

Citation Format: Olga Gordeeva, Irina Kolyadina, Lyudmila Zhukova, Inna Ganshina, Dmitry Komov, Andrey Meshcheryakov. Patterns of survival and efficacy of chemotherapy in elderly patients with triple-negative breast cancer treated in the neoadjuvant setting [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-16-34.

TGFβ Family Signaling Pathways in Pluripotent and Teratocarcinoma Stem Cells' Fate Decisions: Balancing Between Self-Renewal, Differentiation, and Cancer

The transforming growth factor-β (TGFβ) family factors induce pleiotropic effects and are involved in the regulation of most normal and pathological cellular processes. The activity of different branches of the TGFβ family signaling pathways and their interplay with other signaling pathways govern the fine regulation of the self-renewal, differentiation onset and specialization of pluripotent stem cells in various cell derivatives. TGFβ family signaling pathways play a pivotal role in balancing basic cellular processes in pluripotent stem cells and their derivatives, although disturbances in their genome integrity induce the rearrangements of signaling pathways and lead to functional impairments and malignant transformation into cancer stem cells. Therefore, the identification of critical nodes and targets in the regulatory cascades of TGFβ family factors and other signaling pathways, and analysis of the rearrangements of the signal regulatory network during stem cell state transitions and interconversions, are key issues for understanding the fundamental mechanisms of both stem cell biology and cancer initiation and progression, as well as for clinical applications. This review summarizes recent advances in our understanding of TGFβ family functions in naїve and primed pluripotent stem cells and discusses how these pathways are involved in perturbations in the signaling network of malignant teratocarcinoma stem cells with impaired differentiation potential.

HER2 cluster amplification as a factor of an especial sensitivity for anti-HER2 neoadjuvant therapy with biosimilar of trastuzumab in Russian women with breast cancer stage II-III

e12102

Background: Effect of neoadjuvant chemotherapy (NACT) is extremely important for patients with HER2-positive breast cancer stage II-III as it correlates with long-term outcomes. However, predictive factors for achieving complete pathologic response (pCR) remain unclear. Aim of the study: Assess an impact of clinical, morphological and genetic factors on pCR achievement in patients with HER2-positive breast cancer stage II-III treated by biosimilar of trastuzumab. Methods: We studied treatment results in 73 patients with HER2-positive breast cancer (BC) stage II-III (aged 29-71, median – 51 years), treated with NACT with anti-HER2 therapy and radical surgery in “N.N. Blokhin National Medical Research Center of Oncology” оf the Ministry of Health of the Russian Federation in 2015-2018. After radical surgery pathologic response was assessed. Initially operable tumors were observed in 45,2% patients, locally advanced - in 53,4%. Luminal HER2-positive BC was diagnosed in 41,1%, non-luminal HER2-positive in 58,9%. Ki67 was high (≥ 20%) in 91,5%. NACT included anthracycline and non-antracycline regimens with addition of biosimilar of trastuzumab ± pertuzumab. Radical mastectomy was performed in 78,8% patients, 21,2% had breast-conserving surgery. We studied biopsies obtained before the start of treatment in all women, HER2 amplification was detected by HER2 IQFISH pharmDx (DAKO) kit in accordance with ASCO/CAP 2018 guidelines. In 87,1% HER2+ status was defined as ASCO/CAP 2018 category 1; cluster amplification was detected in 30,1% patients. We analyzed the rate of bpCR и tpCR achievement depending on clinical, pathological data and amplification of HER2. Results: Pathologic complete response in primary tumor (bpCR) was achieved in 57,4%, both in primary tumor and lymph nodes (tpCR) – in 48,9% patients; bpCR achievement depended on age, NACT regimen, addition of pertuzumab and HER2 copy number ( < 0,05). The highest rate of bpCR was noted in women aged 50 and older (71,9%, p = 0,026); in patients received TCH±Р regimen (80,0%, p = 0,045); with addition of pertuzumab (88,9%, p = 0,049); and if cluster amplification was detected (81%, p = 0,013). Cluster amplification was the only one significant predictive factor for achieving tpCR: with cluster amplification - 68,8%, without - 38,7% (p = 0,049). Conclusions: Cluster amplification of HER2 is the most significant factor of especial sensitivity for NACT with biosimilar of trastuzumab in HER2-positive BC stage II-III.

Cancer-testis antigens: Unique cancer stem cell biomarkers and targets for cancer therapy

Cancer-testis antigens (CTAs) are considered as unique and promising cancer biomarkers and targets for cancer therapy. CTAs are multifunctional protein group with specific expression patterns in normal embryonic and adult cells and various types of cancer cells. CTAs are involved in regulating of the basic cellular processes during development, stem cell differentiation and carcinogenesis though the biological roles and cell functions of CTA families remain largely unclear. Analysis of CTA expression patterns in embryonic germ and somatic cells, pluripotent and multipotent stem cells, cancer stem cells and their cell descendants indicates that rearrangements of characteristic CTA profiles (aberrant expression) could be associated with cancer transformation and failure of the developmental program of cell lineage specification and germ line restriction. Therefore, aberrant CTA profiles can be used as panels of biomarkers for diagnoses and the selection of cancer treatment strategies. Moreover, immunogenic CTAs are prospective targets for cancer immunotherapy. Clinical trials testing broad range of cancer therapeutic vaccines against antigens of MAGEA and NY-ESO-1 families for treating various cancers have shown mixed clinical efficiency, safety and tolerability, suggesting the requirement of in-depth research of CTA expression in normal and cancer stem cells and extensive clinical trials for improving cancer immunotherapy technologies. This review focuses on recent advancement in study of CTAs in normal and cancer cells, particularly in normal and cancer stem cells, and provides a new insight into CTA expression patterns during normal and cancer stem cell lineage development. Additionally, new approaches in development of effective CTA-based therapies exclusively targeting cancer stem cells will be discussed.

Dose-reduced first cycle of chemotherapy for prevention of life-threatening acute complications in nonseminomatous germ cell tumor patients with ultra high tumor markers and/or poor performance status

PURPOSE

Patients with metastatic nonseminomatous germ cell tumors (mNSGCT) and a high tumor burden or a poor performance status at initial diagnosis are at risk from potentially life-threatening early complications during or after the first chemotherapy cycle. The outcomes with dose-reduced first cycle of chemotherapy in this population of patients are not well established.

METHODS

We performed a retrospective analysis of patients with mNSGCT and International Germ Cell Cancer Collaborative Group (IGCCCG) poor risk features. All patients received cisplatin and etoposide-based combinations as first-line treatment. Ultra high tumor marker levels were defined as α-fetoprotein ≥ 100,000 ng/ml or human chorionic gonadotropin ≥ 200,000 mIU/ml. Before 2005, the first treatment cycle was administered at a full dose in our center. After 2005, we used an abbreviated course of cisplatin and etoposide (EP) for the first cycle, followed by subsequent full-dose administration.

RESULTS

From 1987 to 2012, 265 patients with poor risk features according to IGCCCG received first-line chemotherapy. Among them, 63 out of 265 (24%) patients had ultra high tumor marker levels and/or ECOG performance status of 3-4. Dose reduction of the first chemotherapy cycle was associated with a significant decrease of life-threatening complications from 76 to 44% (p = 0.01), but not with the overall survival (HR 0.99, 95% CI 0.44-2.26).

CONCLUSIONS

Dose reduction of the first EP cycle by 40-60% in the subgroup of poor risk patients with ultra high tumor marker levels and/or ECOG performance status 3-4 is associated with significantly lowered acute complication rates but not with overall survival.

Expression patterns of cancer-testis antigens in human embryonic stem cells and their cell derivatives indicate lineage tracks

Pluripotent stem cells can differentiate into various lineages but undergo genetic and epigenetic changes during long-term cultivation and, therefore, require regular monitoring. The expression patterns of cancer-testis antigens (CTAs) MAGE-A2, -A3, -A4, -A6, -A8, -B2, and GAGE were examined in undifferentiated human embryonic stem (hES) cells, their differentiated derivatives, teratocarcinoma (hEC) cells, and cancer cell lines of neuroectodermal and mesodermal origin. Undifferentiated hES cells and embryoid body cells expressed MAGE-A3, -A6, -A4, -A8, and GAGEs while later differentiated derivatives expressed only MAGE-A8 or MAGE-A4. Likewise, mouse pluripotent stem cells also express CTAs of Magea but not Mageb family. Despite similarity of the hES and hEC cell expression patterns, MAGE-A2 and MAGE-B2 were detected only in hEC cells but not in hES cells. Moreover, our analysis has shown that CTAs are aberrantly expressed in cancer cell lines and display low tissue specificity. The identification of CTA expression patterns in pluripotent stem cells and their derivatives may be useful for isolation of abnormally CTA-expressing cells to improve the safety of stem-cell based therapy.

Differentiation of embryonic stem cells after transplantation into peritoneal cavity of irradiated mice and expression of specific germ cell genes in pluripotent cells

Permanent embryonic stem cell lines (ES cells) are considered as one of the most promising cellular sources for regenerative medicine. ES cells have a high proliferative potency and ability to differentiate into all kinds of somatic and germ cells. However, transplantation of undifferentiated ES cells into adult recipient tissue results in the formation of teratomas. To understand the mechanisms underlying self-renewal and determination of pluripotent cells, we investigated differentiation potencies of undifferentiated ES cells and differentiating embryoid bodies (EB). ES cells and EBs growing on acetate-cellulose membranes were transplanted into the peritoneal cavity of irradiated mice. Behavior and differentiation of transplanted cells were studied within 1, 2, 3, and 6 weeks after transplantation. No differences in the cell composition were found in the teratomas formed by ES cells and differentiating EBs. The pattern of expression of the genes specific for pluripotent and germ cells was studied in all types of experimental teratomas. The expression of oct4, stella, fragilis was detected in the teratomas, but nanog was not expressed. We conclude that pluripotent cells are retained in the experimental teratomas formed after transplantation of ES cells and EBs but the pattern of expression of the studied genes underwent changes.