Antitumor Immune Responses in B2M-Deficient Cancers

β2-microglobulin (B2M) is a critical component of the MHC class I molecule and is required to present tumor antigens to T cells. Its loss results in acquired resistance to immune checkpoint blockade (ICB) therapies. However, there have been well-documented cases of B2M-inactivated tumors responding to ICB, justifying investigation of how an antitumor immune response can be generated to tumors without surface MHC class I. We knocked out B2M in three murine models with varying baseline MHC class I expression and sensitivity to anti-programmed death receptor (PD-1) therapy and analyzed the immune responses. MC38 and YUMMER2.1 without B2M responded to anti-PD-1 alone or with an IL2 agonist, and this was mediated by CD4+ T cells and natural killer (NK) cells. The more aggressive B16 without B2M expression only partially responded to the IL2 agonist, and this was dependent on NK cells. When analyzing nearly 300 pretreatment biopsies from patients with melanoma receiving PD-1 blockade-based therapies, we found infrequent B2M mutations or homozygous loss but more frequent LOH or copy-number gains. B2M LOH was enriched in biopsies from patients without response to therapy, and these biopsies were more frequently infiltrated by activated NK cells. We conclude that in the absence of B2M, activation of CD4+ T cells and NK cells can mediate responses to murine models of PD-1 blockade therapy. In addition, in human melanoma, the intratumoral presence of activated NK cells upon partial B2M loss likely selects against tumor escape through low surface MHC class I expression.

Abstract 5965: B2M loss of heterozygosity in melanoma is associated with increased numbers of activated NK cells and higher expression of the NK cell inhibitory ligand, HLA-G

β2-microglobulin (B2M) is a critical subunit of antigen presenting major histocompatibility complex (MHC) class I molecules. Its genetic inactivation in tumor cells has been implicated in tumor-intrinsic immune escape and immunotherapy resistance. Currently, the impact of B2M dysregulation on tumor-immune dynamics requires furthers characterization. Using a clinical dataset of patients with melanoma treated with immune checkpoint blockade (ICB), whole-exome sequencing and bulk RNA-sequencing data from baseline tumor biopsies (n=295) were analyzed to identify somatic B2M alterations and evaluate correlative clinical outcomes, infiltrating immune cells, and gene expression patterns. No loss-of-function mutations in B2M were found; however, 50% of tumors had B2M alterations in the form of homozygous loss (n=2), loss of heterozygosity (LOH; n=56), or copy number gains (n=88). B2M LOH events were overrepresented in tumors from patients who progressed during ICB therapy compared to those who responded (34% versus 19%; Pearson chi-square test, p=0.035). Additionally, tumors with B2M LOH had lower B2M expression compared to B2M-unaltered tumors (Wilcoxon test, p=0.05). Gene set enrichment analysis revealed reduced expression of immune and inflammatory signatures in B2M-LOH tumors. Furthermore, immune cell deconvolution showed that B2M-LOH tumors had lower total immune cell counts, but greater numbers and proportions of activated natural killer (NK) cells (Wilcoxon test, numbers p=0.021, proportions p=0.032). Differential gene expression analysis revealed concordant higher expression of human leukocyte antigen G (HLA-G), an NK cell inhibitory ligand, in B2M-LOH tumors (Wilcoxon test, p=0.0035). Moreover, B2M-LOH progressive tumors had the highest median HLA-G expression and trended toward a positive correlation between increasing HLA-G expression and increasing numbers of activated NK cells (Pearson correlation, r=0.55, p=0.015). In conclusion, melanoma biopsies with B2M LOH were associated with non-response to ICB, had increased presence of activated NK cells, and demonstrated a compensatory increase in HLA-G. These results suggest that in melanoma B2M alterations may be implicated in modulating NK cell interactions and point toward HLA-G potentially playing a role in inhibiting NK cell anti-tumor activity.

Citation Format: Mildred Galvez, Katie M. Campbell, Egmidio Medina, Antoni Ribas. B2M loss of heterozygosity in melanoma is associated with increased numbers of activated NK cells and higher expression of the NK cell inhibitory ligand, HLA-G [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5965.

Remodeling of the tumor microenvironment through PAK4 inhibition sensitizes tumors to immune checkpoint blockade

PAK4 inhibition can sensitize tumors to immune checkpoint blockade (ICB) therapy, however, the underlying mechanisms remain unclear. We report that PAK4 inhibition reverses immune cell exclusion by increasing the infiltration of CD8 T cells and CD103+ dendritic cells (DCs), a specific type of DCs that excel at cross-presenting tumor antigens and constitute a source of CXCL10. Interestingly, in melanoma clinical datasets, PAK4 expression levels negatively correlate with the presence of CCL21, the ligand for CCR7 expressed in CD103+ DCs. Furthermore, we extensively characterized the transcriptome of PAK4 knock out (KO) tumors, in vitro and in vivo, and established the importance of PAK4 expression in the regulation of the extracellular matrix, which can facilitate immune cell infiltration. Comparison between PAK4 wild type (WT) and KO anti-PD-1 treated tumors revealed how PAK4 deletion sensitizes tumors to ICB from a transcriptomic perspective. In addition, we validated genetically and pharmacologically that inhibition of PAK4 kinase activity is sufficient to improve anti-tumor efficacy of anti-PD-1 blockade in multiple melanoma mouse models. Therefore, this study provides novel insights into the mechanism of action of PAK4 inhibition and provides the foundation for a new treatment strategy that aims to overcome resistance to PD-1 blockade by combining anti-PD-1 with a small molecule PAK4 kinase inhibitor.

Abstract 1388: Mutations in transcriptional activators of MHC I antigen presentation, NLRC5 and CIITA, are mutually exclusive and have different effects on melanoma gene transcripts

Response to many immunotherapies depends on effective recognition and eradication of tumor cells by the immune system. This is mediated by the successful presentation of tumor-specific antigens on major histocompatibility complex class I (MHC I) molecules on the surface of tumor cells. Studies have focused on alterations in MHC I complex proteins (e.g. HLA, B2M) and gene regulatory elements (e.g. NLRC5). However, the impact on tumor response of individual defects in components regulating and composing the MHC I antigen processing and presentation machinery (APM) have not been extensively studied. Using a harmonized dataset of six clinical trials of patients with melanoma treated with ICB, whole-exome sequencing (WES, n= 244) and RNA sequencing (RNAseq, n= 426) data from untreated tumor samples were assessed to identify mutations in genes associated with MHC I APM and their regulation. Somatic alterations were correlated with clinical response to ICB and with gene expression profiles in tumor-matched RNAseq data. Mutations in MHC I and MHC I-related genes were found in 63% of patients (n= 154/244). The most recurrently mutated genes were NCAM1 (11%, n=28), TRIM48 (7%, n=17), and CAMK2B (6.6%, n=16), and the transcriptional regulators NLRC5 (9.4%, n=23) and CIITA (9.4%, n=23). Mutations in NLRC5 and CIITA trended toward being mutually exclusive from one another (Fisher’s exact test, p= 0.157) and mutations were overrepresented in tumors with stable or progressive disease following ICB therapy. In addition, lower expression of NLRC5 and CIITA were associated with stable or progressive disease status. NLRC5-mutant tumors that progressed following ICB therapy trended towards lower expression of transcriptional target HLA-A (Kruskal-Wallis, p=0.27); however, there was no difference in HLA-A expression across NLRC5-wildtype tumors. For class II transactivating factor, CIITA, which can induce MHC I expression, mutational status was not associated with HLA-A expression across all clinical response groups. There are genetic alterations spanning MHC I and MHCI-associated genes that may be responsible for inactivating class I antigen presentation by melanoma cells. The impact of these alterations may result in varied clinical responses to ICB therapies. The landscape of these alterations needs to be further delineated to understand how tumors are directly evading class I-mediated recognition and elimination.

Citation Format: Mildred Galvez, Katie M. Campbell, Egmidio Medina, Antoni Ribas. Mutations in transcriptional activators of MHC I antigen presentation, NLRC5 and CIITA, are mutually exclusive and have different effects on melanoma gene transcripts [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 1388.

Unique challenges for glioblastoma immunotherapy-discussions across neuro-oncology and non-neuro-oncology experts in cancer immunology. Meeting Report from the 2019 SNO Immuno-Oncology Think Tank

Cancer immunotherapy has made remarkable advances with over 50 separate Food and Drug Administration (FDA) approvals as first- or second-line indications since 2015. These include immune checkpoint blocking antibodies, chimeric antigen receptor-transduced T cells, and bispecific T-cell-engaging antibodies. While multiple cancer types now benefit from these immunotherapies, notable exceptions thus far include brain tumors, such as glioblastoma. As such, it seems critical to gain a better understanding of unique mechanistic challenges underlying the resistance of malignant gliomas to immunotherapy, as well as to acquire insights into the development of future strategies. An Immuno-Oncology Think Tank Meeting was held during the 2019 Annual Society for Neuro-Oncology Scientific Conference. Discussants in the fields of neuro-oncology, neurosurgery, neuro-imaging, medical oncology, and cancer immunology participated in the meeting. Sessions focused on topics such as the tumor microenvironment, myeloid cells, T-cell dysfunction, cellular engineering, and translational aspects that are critical and unique challenges inherent with primary brain tumors. In this review, we summarize the discussions and the key messages from the meeting, which may potentially serve as a basis for advancing the field of immune neuro-oncology in a collaborative manner.

CTIM-19. MOLECULAR AND GENETIC DETERMINANTS OF RESPONSE TO PD-1 BLOCKADE IN RECURRENT GLIOBLASTOMA PATIENTS

Despite immune checkpoint inhibitors having success in several other tumor types, many glioblastoma (GBM) patients fail to respond or maintain a sustained response. Work published by our group (Cloughesy et al, 2019) demonstrated that relative to adjuvant programmed cell death-1 (PD-1) blockade, neoadjuvant treatment doubled the median overall survival (OS) for recurrent GBM patients and resulted in an enhanced interferon-γ signature. This suggests that anti-PD-1 given in the neoadjuvant setting may improve outcomes for recurrent GBM patients. The challenge remains in identifying the molecular and genetic signatures associated with response to immune checkpoint blockade. To address this, we analyzed the tumor sample and clinical response data from the patients treated in this clinical trial (n=31). We stratified patients as stable disease (SD) versus progressive disease (PD) based on their response assessment in neuro-oncology criteria (RANO) scores from cycle 2 of treatment post-surgery. Among the SD patients, 77.8% received neoadjuvant treatment while 22.2% received adjuvant therapy. In this group, a median OS was not reached. Among the PD patients, 40.9% received neoadjuvant treatment and 59.1% received adjuvant therapy, with a median OS of 257 days. Next, we analyzed factors that impact response to immunotherapy, which includes somatic mutational burden and interferon-γ pathway induction. We calculated somatic mutational variants, copy number variants (CNVs), and differential gene expression from the bulk tumor exome and RNA-sequencing data. The total mutation counts were similar between groups and no association was identified with increased mutational burden. In addition, total CNV stability was similar between groups. However, when looking at genes involved in the JAK/STAT signaling pathway, there were notably more copy number losses of JAK2 in the PD group when compared to the SD group (85.0% versus 66.7%). These findings merit further exploration as the JAK/STAT pathway has been implicated in response to immune checkpoint blockade.

IMMU-20. SINGLE-CELL RNASEQ OF TUMOR INFILTRATING IMMUNE CELLS FROM NEOADJUVANT ANTI-PD1 TREATED GBM PATIENTS REVEALS GLOBAL TRANSCRIPTIONAL CHANGES AND IMMUNOSUPPRESSIVE ADAPTIVE RESPONSES BY MYELOID CELLS

INTRODUCTION

Neoadjuvant anti-PD1 therapy (neo-aPD1) was previously shown to significantly increase the survival of recurrent glioblastoma patients in a small randomized clinical trial. However, neo-aPD1 alone was not curative so defining the limitations of neo-aPD1 and discovering where other immunotherapies can be used alongside neo-aPD1 is needed.

METHODS

To understand how immune cells in the tumor microenvironment change with neo-aPD1, we used single-cell RNAsequencing to analyze cells from 27 glioma patients (n = 105,143 cells) of which 9 patients had received neo-aPD1 (n = 33,325 cells). Using unsupervised clustering and pseudotime trajectory analysis, we characterized the transcriptional changes within immune cells and how these populations changed with therapy.

RESULTS

We defined the immune landscape of the glioblastoma tumor microenvironment. Compared to no immunotherapy treatment, neo-aPD1 significantly increased the ratio of T cells to myelo-monocytic cells and led to significant increases in the effector and memory T cell populations but no significant changes in myeloid cell composition. Our differential gene expression analysis of the myeloid compartment showed significant increases in interferon-γ-responsive genes and down-regulation of genes associated with M2 macrophages and MDSCs, suggestive that neo-aPD1 influences the transcriptional profile of myeloid cells in the tumor microenvironment. Interestingly, our psuedotime trajectory analysis showed that neo-aPD1 was associated with cells expressing both lymphoid and myeloid-related genes, which we theorized to actually be lymphoid-myeloid cell doublets caused by increased interactions between myeloid and lymphoid cells. These doublets were highly enriched in MHC I and II, macrophage, T cell, and T cell activation and exhaustion genes indicating that neo-aPD1 may result in some adaptive immunosuppressive mechanism by increasing these interactions. This could explain why neo-aPD1 alone is not curative for glioblastoma patients.

CONCLUSIONS

In total, neoadjuvant anti-PD1 therapy enhances effector T cell activity, but may concomitantly induce adaptive resistance mediated by myeloid cells in glioblastoma.

IMMU-02. NEOANTIGENS ARISING FROM ALTERNATIVE SPLICING EVENTS MAY BE TARGETED BY TUMOR INFILTRATING LYMPHOCYTES IN GLIOBLASTOMAS

INTRODUCTION

Alternative splicing, the cellular process that converts premature mRNA to mature mRNA and allows for single genes to produce multiple protein products, is frequently dysregulated in many cancers, including glioblastoma. However, along with non-synonymous mutations in the DNA, altered splicing mechanisms in cancers may produce novel antigens (so-called neoantigens) that distinguish cancer cells from healthy cells and can thus be targeted by the immune system.

METHODS

We developed a new computation pipeline (IRIS – Isoform peptides from RNA splicing for Immunotherapy targets Screening) that took bulk RNA-sequencing data from 23 glioblastoma patient tumor samples and predicted neoantigens that may arise from alternative splicing events. We prioritized predicted neoantigens that arose in HLA*A02:01 and HLA*A03:01 patients and selected 8 potential neoantigens to generate peptide:MHC Class 1 dextramers. We tested PBMCs and/or ex vivo expanded tumor infiltrating lymphocytes (TIL) from 6 of our glioblastoma patients against these dextramers, sorted for any neoantigen-reactive T cells, and performed single-cell RNAsequencing on the sorted population to determine the TCR sequence.

RESULTS

Among the 8 predicted neoantigens tested, 7 of the neoantigens were recognized by at least 1 patient’s T cells. 1 HLA*A03:01 epitope was recognized in 3 of the 4 HLA*A03:01 patients tested and this epitope was highly positive in an expanded TIL population, representing 1.7% of all CD3+ CD8+ cells. When we sorted for those neoantigen reactive T cells from the expanded TIL population and performed single-cell RNAsequencing, we found 325 unique T cell clonotypes, but the top 10 clonotypes represented 83.6% of all TCR clonotypes. The most frequent TCR clonotype represented 39.1% of the repertoire and suggests that clonal expansion of a select few TCR clones occurred within the tumor.

CONCLUSIONS

In total, our data indicates that neoantigens arising from alternative splicing events may represent a potential target for immunotherapy in glioblastoma.

ATIM-16. VALIDATION OF RESPONSE TO NEOADJUVANT ANTI-PD-1 IMMUNOTHERAPY IN RECURRENT GLIOBLASTOMA

BACKGROUND

Recurrent glioblastoma has a poor median overall survival despite multimodal treatment. The use of pembrolizumab, an anti-PD-1 monoclonal antibody, demonstrates promise, including improved overall survival and increased immune response, when used in the neoadjuvant setting.

METHODS

We evaluated 13 patients with surgically accessible recurrent glioblastoma who were treated at the University of California, Los Angeles with neoadjuvant checkpoint inhibition prior to tumor resection. Combining data with our previously published multi-center study, we followed this cohort prospectively, performing tumor gene expression to validate the immune response and improved survival following neoadjuvant therapy with pembrolizumab.

RESULTS

When combined with findings from our prior study, patients in the neoadjuvant group (n = 27) had an overall survival of 400 days, whereas those in the adjuvant-only group (n = 19) had a median overall survival of 228 days by Kaplan-Meier estimator (P = 0.029, log-rank test). Progression-free survival in the neoadjuvant group was 108 days, whereas in the adjuvant-only group it was 72.5 days (P = 0.017, log-rank test). In elastic net penalized Cox proportional hazards regression, neoadjuvant anti-PD-1 blockade continued to be associated with improved overall survival, with a hazard ratio of 0.11 (P=0.003, log-rank test). Bulk tumor gene expression corroborates our previously described pattern of increased T-cell- and IFN-g-related gene expression, decreased cell-cycle-related signatures and their association with clinical response. Additionally, epigenetic regulation inversely correlated with clinical response.

CONCLUSIONS

Our findings support the neoadjuvant timing of PD-1 blockade in enhancing local immune responses and prolonging overall- and progression-free-survival. Correlative biological studies suggest a potential role for cell-cycle-related gene expression as a biomarker to predict response to therapy. Continued data collection and the addition of patients to the neoadjuvant arm of the trial, will be crucial to determine the potential role of checkpoint inhibition in the treatment of this deadly disease.

TMIC-06. MYELOID POPULATIONS AND THE EFFECT OF NEOADJUVANT PD-1 INHIBITION IN THE GLIOBLASTOMA MICROENVIRONMENT: A SURFACEOMIC AND TRANSCRIPTOMIC DISSECTION AT THE SINGLE-CELL LEVEL

INTRODUCTION

Glioblastoma (GBM) is the most common malignant brain tumor in adults and is associated with a dismal prognosis. Neoadjuvant anti-PD-1 blockade has demonstrated efficacy in melanoma, non-small cell lung cancer and recurrent GBM; however, responses vary. While T cells have garnered considerable attention in the context of immunotherapy, the role of myeloid cells in the GBM microenvironment remains controversial.

METHODS

We isolated CD45+ immune populations from patients who underwent brain tumor resection at UCLA. We hypothesized that myeloid cells in glioblastoma contribute to T cell dysfunction; however, this immune suppression can be mitigated by neoadjuvant PD-1 inhibition. To test this, we utilized mass cytometry and single-cell RNA sequencing to characterize these immune populations.

RESULTS

Mass cytometry profiling of tumor infiltrating lymphocytes from patients with GBM demonstrated a preponderance of CD11b+ myeloid populations (75% versus 25% CD3+). At the transcriptomic level, myeloid cells in newly diagnosed GBMs exhibited decreased expression of CCL4 (loge fold change -1.18, Bonferroni-adjusted P = 1.62x10-254) and its ligands compared to anaplastic astrocytoma. In ranked gene set enrichment analysis, patients who received neoadjuvant pembrolizumab demonstrated enrichment in TNFα-, NFκB- and lipid metabolism-related gene sets by bootstrapped Kolmogorov-Smirnov test (Benjamini-Hochberg adjusted P = 4.74x10-3, 1.45x10-2 and 2.48x10-3, respectively) in tumor-associated myeloid populations. Additionally, single-cell trajectory analysis demonstrated increased CCL4 and decreased ISG15 with neoadjuvant checkpoint inhibition.

CONCLUSIONS

Here, we utilize mass cytometry and single-cell RNA sequencing to demonstrate the predominance and transcriptomic features of myeloid populations in GBM. Myeloid cells in patients who receive neoadjuvant PD-1 blockade re-express increased levels NFκB, TNFα and CCL4, a cytokine crucial for the recruitment of dendritic cells to the tumor for antigen-specific T cell activation. By delving into the GBM microenvironment at the single-cell level, we hope to better delineate the role of myeloid populations in this uniformly fatal tumor.

Abstract P2-14-12: Impact of the time interval between neoadjuvant chemotherapy and surgery in Latin-Americans breast cancer patients

Background: Few studies have evaluated the impact of the time interval between neoadjuvant chemotherapy (NAC) and surgery in breast cancer. In Latin America, where the vast majority of hospitals are oversaturated, it is important to define which patients to give priority and to be clear about ideal time or maximum to schedule surgery after NAC without altering the prognosis. The objective of this work is to establish the ideal time interval for post-neoadjuvant surgery and evaluate the impact on patient survival.

Methods: We reviewed the clinical histories of breast cancer with clinical stage II and III who received NAC between 2005 and 2014. Patients were divided into 3 groups according to the time interval to surgery: <4, 4-8 and >8 weeks. Overall survival (OS) and recurrence-free survival (RFS) were estimated using the Kaplan-Meier method, and comparisons of survival curves using the logrank or Breslow test, both globally and by molecular subtypes. The optimal time to surgery has been determined by the Cox model.

Results: During the study period, 583 patients who had post NA surgery before six months were registered. The median age was 49 years (range: 24-85), 82% had clinical stage III, 53% histological grade III, 32.7% were luminal A, 15.6% luminal B, 24.4% Her2 and 27.3% TN. According to the time interval to surgery, 67 (11.5%) patients had surgery before 4 weeks, 204 (35.0%) between 4 to 8 weeks, and 312 (53.5%) after 8 weeks. The groups do not present differences in relation to the clinical characteristics (p> 0.05). The median follow-up time was 4.8 years. The 5-year OS rate according to the time interval was 57.9, 61.5, and 62.7% (p = 0.581) and the RFS rate was 40.6, 52.3, and 51.1% (p = 0.411). No differences were found in the survival curves by molecular subtypes , except for luminal b like . In the multivariate analysis, the effect of the time interval to surgery was not significant in OS and RFS; however, the HR curve suggests that the appropriate cut-off point for surgical time would be 8 weeks.

Table 1:Time Interval :OS - RFS  RFS  OS  MEDIAN5 - yearsPMEDIAN5 - yearsPWeeks for NAC to Surgery      <4 weeks3.240.6 6.157.9 4-8 weeks6.352.3 9.161.5 >8 weeks5.151.10.416.762.70.581       Weeks for NAC to Surgery      <8 weeks549.5 9.160.7 >8 weeks5.151.10.5856.762.70.414

Table 2 :Time Interval - Molecular Subtype  RFS  OS  MEDIAN5 - yearsPMEDIAN5 - yearsPLUMINAL A LIKE      < 8 weeks----74.1 ----84 >8 weeks7.163.80.719.973.90.236       *LUMINAL B LIKE      < 8 weeks2.336.8 5.460.5 >8 weeks5.857.60.46----820.08       HER2      <8 weeks2.228.7 3.938.4 >8weeks3.645.90.57.26.261.30.616       TRIPLE NEGATIVE      <8 weeks3.144.2 3.448.4 >8 weeks2.041.80.9143.743.90.516* ER + PR >20% KI67>14% , HER2 NEGATIVE

Conclusion: The time interval between the end of neoadjuvant period and surgery has no impact on recurrence-free survival or on overall survival, despite this we suggest that the period of time between neoadjuvant and surgery not be greater than 8 weeks. More studies will be required to determine the ideal time interval and which cases should be prioritized according to the characteristics of our patients.

Citation Format: Rebaza LP, Galarreta JA, Castañeda C, Cotrina JM, Vilchez S, de la Cruz M, Ponce J, Aguilar A, Flores C, Castillo M, Galvez M, Vigil C. Impact of the time interval between neoadjuvant chemotherapy and surgery in Latin-Americans breast cancer patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-14-12.

Expression of PD-1 by T Cells in Malignant Glioma Patients Reflects Exhaustion and Activation

PURPOSE

Glioblastoma (GBM) is the most common primary malignant tumor in the central nervous system. Our recent preclinical work has suggested that PD-1/PD-L1 plays an important immunoregulatory role to limit effective antitumor T-cell responses induced by active immunotherapy. However, little is known about the functional role that PD-1 plays on human T lymphocytes in patients with malignant glioma.Experimental Design: In this study, we examined the immune landscape and function of PD-1 expression by T cells from tumor and peripheral blood in patients with malignant glioma.

RESULTS

We found several differences between PD-1⁺ tumor-infiltrating lymphocytes (TIL) and patient-matched PD-1⁺ peripheral blood T lymphocytes. Phenotypically, PD-1⁺ TILs exhibited higher expression of markers of activation and exhaustion than peripheral blood PD-1⁺ T cells, which instead had increased markers of memory. A comparison of the T-cell receptor variable chain populations revealed decreased diversity in T cells that expressed PD-1, regardless of the location obtained. Functionally, peripheral blood PD-1⁺ T cells had a significantly increased proliferative capacity upon activation compared with PD-1^- T cells.

CONCLUSIONS

Our evidence suggests that PD-1 expression in patients with glioma reflects chronically activated effector T cells that display hallmarks of memory and exhaustion depending on its anatomic location. The decreased diversity in PD-1⁺ T cells suggests that the PD-1-expressing population has a narrower range of cognate antigen targets compared with the PD-1 nonexpression population. This information can be used to inform how we interpret immune responses to PD-1-blocking therapies or other immunotherapies.

Abstract P6-15-04: Characterization of tumor infiltrating lymphocytes and its association response in breast cancer

Background: The magnitude of tumor infiltrating lymphocytes (TIL) is a predictor of good prognosis in the context of neoadyuvant chemotherapy (NAC) in breast cancer, and is expressed in the capacity to achieve a pathological complete response (pCR) and therefore to obtain a major survival. The characteristics of TIL are influenced of different clinical and pathological features as well as its predictive value. The goal of this study is to define the different associations between level of stromal (sTIL) and interstitial (iTIL) tumor infiltrating lymphocytes and pathological and clinical feature of breast cancer. Methods: The level of TIL was analyzed in 483 patients diagnosed with breast cancer of the Instituto Nacional de Enfermedades Neoplasicas from 2003 to 2014. We evaluate patient characteristics such as age, clinical stage, histological subtype and grade, clinical T, N and M, presence of estrogen (ER) and progesterone (PgR) receptors, HER-2 expression and molecular subtype as well as pathological response. Results: We found a positive association between sTIL and iTIL proportion and histological grade (G1-2 vs G3, p<0.05 and p<0.05 respectively), hormone receptor (ER- vs ER+PgR- vs ER+PgR+, p<0.05 and p=0.001 respectively), molecular subtype (Luminal A vs Luminal B vs HER2 vs Triple Negative (TN), p<0.05 and p=0.002 respectively), clinical N (positive vs negative, p=0.006 and p<0.05 respectively). Also we found association between sTIL with lymph nodes after surgery (negative vs positive, p=0.028) and pathological response (pCR vs <pCR, p=0.018), there was no association between sTIL and iTIL with age, histological subtype, clinical T and M. Conclusions: The level of tumor infiltrating lymphocytes are affected by different clinical and pathological features, they are present in both lobular and ductal breast cancer without significant difference; higher level of TIL are associated with high histological grade, ER-, TNBC and high clinical N to diagnosis; and specially sTIL are associated with to achieve a negative lymph node after NAC and obtain a pathological complete response.

Citation Format: Galvez M, Castaneda C, Villegas V. Characterization of tumor infiltrating lymphocytes and its association response in 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 P6-15-04.

Phthalate exposure and pubertal development in a longitudinal study of US girls

STUDY QUESTION

Does phthalate exposure during early childhood alter the timing of pubertal development in girls?

SUMMARY ANSWER

Urinary concentrations of high-molecular weight phthalate (high-MWP) metabolites are associated with later pubarche.

WHAT IS KNOWN ALREADY

Phthalates are anti-androgenic environmental agents known to alter early development, with possible effects on pubertal onset.

STUDY DESIGN, SIZE, AND DURATION

This multi-ethnic study included 1239 girls from New York City, greater Cincinnati, and the San Francisco Bay Area who were 6-8 years old at enrollment (2004-2007) and who were followed until 2011. PARTICIPANTS/MATERIALS, SETTING, METHODS Phthalate metabolites were measured in urine collected at enrollment from 1170 girls; concentrations ranged from <1 to >10,000 µg/l. Breast and pubic hair stages and body size were assessed one to two times annually to determine the age at transition from stage 1 to 2 for breast and pubic hair development. Associations between exposures and pubertal ages were estimated using Cox proportional hazard ratios (HR) with 95% confidence intervals (CI) and survival analyses. Associations were examined with respect to age-specific body mass-index percentile, one of the strongest predictors of pubertal onset.

MAIN RESULTS AND THE ROLE OF CHANCE

Urinary concentrations of high-MWP including di(2-ethylhexyl) phthalate (ΣDEHP) metabolites were associated with later pubic hair development during 7 years of observation. The relationship was linear and was stronger among normal-weight girls. Among normal-weight girls, age at pubic hair stage 2 (PH2) was 9.5 months older for girls in the fifth compared with the first quintile of urinary ΣDEHP (medians: 510 and 59 µg/g creatinine, respectively; adjusted HR 0.70, CI 0.53-0.93, P-trend 0.005. Age at first breast development was older for fifth quintile of mono-benzyl phthalate versus first (HR 0.83, CI 0.68-1.02; P-trend 0.018). No associations were observed between low-molecular weight phthalate urinary metabolite concentrations and age at pubertal transition in adjusted analyses.

LIMITATIONS, REASONS FOR CAUTION

While there is evidence that phthalate exposures are fairly consistent over time, the exposure measure in this study may not reflect an earlier, more susceptible window of exposure. We investigated alternative explanations that might arise from exposure misclassification or confounding.

WIDER IMPLICATIONS OF THE FINDINGS

Phthalates are widespread, hormonally active pollutants that may alter pubertal timing. Whether exposures delay or accelerate pubertal development may depend on age at exposure as well as other factors such as obesity and exposures earlier in life. Whether exposures act independently or as part of real life mixtures may also change their effects on maturation from birth through childhood.

STUDY FUNDING/COMPETING INTEREST(S)

This project was supported by the US National Institutes of Health, Environmental Protection Agency, New York State Empire Clinical Research Investigator Program and the Avon Foundation. L.H.K. is employed by Kaiser Permanente. The remaining authors declare they have no actual or potential competing financial interests.

Coronary extraction and stenosis quantification in X-ray angiographic imaging

This work describes a method to quantify stenosis in X-ray coronary angiography. Vascular edge extraction is first performed based on a deformable spline algorithm. It makes use of directional S-Gabor filters to build an external energy field that is then used in a snake optimisation scheme. A string matching technique is then applied to match the contour points and obtain a trace between the matched points. This trace allows then computing the vessel diameter and deriving quantitative stenosis measurements. Experimental results are presented on simulated data and real images.

Haplotype analysis of a BRCA1: 185delAG mutation in a Chilean family supports its Ashkenazi origins

At least 25% of Ashkenazi Jewish families with two or more cases of premenopausal breast cancers are attributable to one of three founder mutations in BRCA1 or BRCA2. As these three founder mutations are common in the Ashkenazi Jewish population ( approximately 2.5%) and can easily be tested for in a multiplex assay, establishing ethnicity can expedite genetic testing. It is not always possible, however, to conclusively establish ethnicity before offering testing. We report here the occurrence of a founder Ashkenazi Jewish BRCA1 mutation, 185delAG (also known as 187delAG), in a non-Jewish Chilean family with no reported Jewish ancestry. The linked haplotype present in this family was identical to that identified in the Ashkenazi Jewish population. This case report not only illustrates the problem of the definition of ethnicity but also points to the possibility of further studies of the frequency of founder Ashkenazi Jewish mutations in populations not generally considered to be of Ashkenazi Jewish origin.

Factors in the accumulation of dieldrin in broiler organs: quantity ingested, sex and weight of animal

The effect of several factors in relation to the quantities of dieldrin accumulated in different organs of broilers was studied. Feedstuff was contaminated at doses of 60, 90, 120, 200 and 240 ppm. With the doses used, the results show an accumulation summit over which the amounts accumulated are not affected by greater quantities of dieldrin ingested. The accumulation of dieldrin in the female is greater than in the male and the weight of the animal does not significantly affect the response.

Study of luteal function

On studying various parameters of luteal function, the authors demonstrated that BTT does not permit the evaluation of luteal phase defects, whereas the E.I. and prolactin levels, as well as the endometrial biopsy, may be considered valid parameters. The TRH test is more efficient than basal prolactin evaluation in this respect. Progesterone should be evaluated in various moments of the luteal phase and not by a single determination. The authors conclude that the abnormal luteal phase is the result of an abnormal follicular maturation and that the central origin of this mechanism may be affirmed.