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Purpose: Women have traditionally been underrepresented in MD and MD-PhD training programs. Here, we describe the changing demographics of an MD-PhD Program over three distinct time intervals. Methods: We designed a 64-question survey and sent it to 47 graduates of the McGill University MD-PhD program in Montréal, Québec, Canada, since its inception in 1985. We also sent a 23-question survey to the 24 students of the program in 2021. The surveys included questions related to demographics, physician-scientist training, research metrics, as well as academic and personal considerations.Results: We collected responses from August 2020 to August 2021 and grouped them into three intervals based on respondent graduation year: 1995–2005 (n = 17), 2006–2020 (n = 23) and current students (n = 24). Total response rate was 90.1% (n = 64/71). We found that there are more women currently in the program compared to the 1995–2005 cohort (41.7% increase, p

Immune checkpoint inhibitors (ICI) are highly effective in specific cancers where canonical markers of antitumor immunity are used for patient selection. Novel predictors of T cell-inflammation are needed to identify ICI-responsive tumor subsets in additional cancer types. We investigated associations of a 4-chemokine expression signature (c-Score: CCL4, CCL5, CXCL9, CXCL10) with metrics of antitumor immunity across tumor types. Across cancer entities from The Cancer Genome Atlas, subgroups of tumors displayed high expression of the c-Score (c-Scorehi) with increased transcriptional hallmarks of the cancer-immunity cycle, while high tumor mutation burden (TMB) was associated with only a subset of c-Scorehi tumors. Among 82 patients treated with ICIs, the c-Scorehi subgroup exhibited longer median time to progression (103 versus 72 days, P=0.012) and overall survival (382 versus 196 days, P=0.038), and the c-Score outperformed TMB for overall survival prediction. Taken together, the c-Score identifies patients with hallmarks of T cell-inflammation and response to ICI treatment across cancer types.

SummaryPancreatic ductal adenocarcinoma (PDAC) remains resistant to most treatments and demonstrates a complex pathobiology. Here, we deconvolute regional heterogeneity in the human PDAC tumor microenvironment (TME), a long-standing obstacle, to define precise stromal contributions to PDAC progression. Large scale integration of histology-guided multiOMICs with clinical data sets and functional in vitro models uncovers two microenvironmental programs in PDAC that were anchored in fibroblast differentiation states. These sub-tumor microenvironments (subTMEs) co-occurred intratumorally and were spatially confined, producing patient-specific cellular and molecular heterogeneity associated with shortened patient survival. Each subTME was uniquely structured to support discrete aspects of tumor biology: reactive regions rich in activated fibroblast communities were immune-hot and promoted aggressive tumor progression while deserted regions enriched in extracellular matrix supported tumor differentiation yet were markedly chemoprotective. In conclusion, PDAC regional heterogeneity derives from biologically distinct reactive and protective TME elements with a defined, active role in PDAC progression.Graphical Abstract & Key findingsPDAC regional heterogeneity originates in sub-tumor microenvironments (subTMEs)SubTMEs exhibit distinct immune phenotypes and CAF differentiation statesDifferent subTMEs are either tumor-promoting or chemoprotectiveIntratumoral subTME co-occurrence links stromal heterogeneity to patient outcome

2558 Background: Immune checkpoint inhibitors (ICI) are highly effective in select cancers. Novel predictors of T cell-inflammation may identify a broader subset of tumors with ICI responsiveness. Our group has identified four chemokines (CCL4, CCL5, CXCL9, CXLC10) able to predict a T cell-inflamed phenotype in primary and metastatic pancreatic tumors. Here, we test whether this 4-chemokine signature can predict T cell-inflammation across additional tumor types and response to ICI. Methods: Using matched genomic and transcriptomic data from 6,455 patients spanning 25 tumor types from The Cancer Genome Atlas, we searched for associations between the 4-chemokine signature and metrics of antitumor immunity. Further, we tested the association of this signature with markers of DNA damage repair deficiency. We also investigated the ability of this signature to predict response to immunotherapy using real-world data from a pan-cancer cohort of 82 patients in the Personalized OncoGenomics Program who had received ICI. Results: The majority of tumor types displayed sub-populations with high expression of the 4-chemokines (4-chemokinehi) and transcriptional hallmarks of the cancer-immunity cycle. Testicular germ cell tumors, cervical squamous cell carcinomas, and head and neck squamous cell carcinomas were the strongest expressors of the signature. Immunomodulatory genes, including PD-L1, PD-1, TIM3, LAG3, TIGIT, CTLA-4, and FASLG, were significantly overexpressed (phi cohorts. Genesets of processes involved in the cancer-immunity cycle, including MHC I expression and cytolytic activity, were upregulated in the 4-chemokinehi cohorts (phi tumors. Among patients treated with ICIs, those with 4-chemokinehi tumors had a longer median time to progression (104 versus 71 days, p=0.013) and overall survival (391 versus 195 days, p=0.016). The 4-chemokine signature outperformed TMB for overall survival prediction. Conclusions: Sub-populations of T cell-inflamed patients exist across tumor types and may therefore respond favourably to ICI. The 4-chemokine signature has the potential to select a wider spectrum of patients that may benefit from ICIs. [Table: see text]

MicroRNAs (miRNAs) are small noncoding RNA molecules that post-transcriptionally regulate gene expression. Dysregulation of miRNAs is frequently associated with disease and, in particular, is involved in prostate cancer progression. Next generation miRNA sequencing identified a panel of five miRNAs associated with prostate cancer recurrence and metastasis. High expression of one of these five miRNAs, miR-652, correlated significantly with an increased rate of prostate cancer biochemical recurrence. Overexpression of miR-652 in prostate cancer cells, PC3 and LNCaP, resulted in increased growth, migration and invasion. Prostate cancer cell xenografts overexpressing miR-652 showed increased tumorigenicity and metastases. We found that miR-652 directly targets the B” regulatory subunit, PPP2R3A, of the tumor suppressor PP2A, inducing epithelial-mesenchymal transition (EMT) in PC3 cells and neuroendocrine-like differentiation (NED) in LNCaP cells. The mesenchymal marker N-cadherin increased and epithelial marker E-cadherin decreased in PC3 cells overexpressing miR-652. In LNCaP cells and xenografted tumors, overexpression of miR-652 increased markers of NED, including chromogranin A, neuron specific enolase, and synaptophysin. MiR-652 may contribute to prostate tumor progression by promoting NED through decreased PP2A function. MiR-652 expression could serve as a biomarker for aggressive prostate cancer, as well as provide an opportunity for novel therapy in prostate cancer.

Intratumoral heterogeneity is a critical frontier in understanding how the tumor microenvironment (TME) propels malignant progression. Here, we deconvolute the human pancreatic TME through large-scale integration of histology-guided regional multiOMICs with clinical data and patient-derived preclinical models. We discover "subTMEs," histologically definable tissue states anchored in fibroblast plasticity, with regional relationships to tumor immunity, subtypes, differentiation, and treatment response. "Reactive" subTMEs rich in complex but functionally coordinated fibroblast communities were immune hot and inhabited by aggressive tumor cell phenotypes. The matrix-rich "deserted" subTMEs harbored fewer activated fibroblasts and tumor-suppressive features yet were markedly chemoprotective and enriched upon chemotherapy. SubTMEs originated in fibroblast differentiation trajectories, and transitory states were notable both in single-cell transcriptomics and in situ. The intratumoral co-occurrence of subTMEs produced patient-specific phenotypic and computationally predictable heterogeneity tightly linked to malignant biology. Therefore, heterogeneity within the plentiful, notorious pancreatic TME is not random but marks fundamental tissue organizational units.

Despite remarkable responses in several cancer types, immune checkpoint blockade (ICB) remains ineffective against a subset of tumors, including those presently recalcitrant to conventional treatment modalities. Given the ubiquitous nature of genomic aberrations in cancer and the potential roles they have in eliciting an immune-mediated antitumor response, genomic predictors of T cell-inflammation may help segregate patients responsive to ICB. Tumors with homologous recombination repair deficiencies (HRD) exhibit hypermutation and may therefore potentially harbour a genetically favourable milieu to elicit an antitumor immune response. However, the exact role of HRD in antitumor immunity remains unclear. Given that HRD accounts for up to 10% of pancreatic cancers and a higher proportion in ovarian cancers, the use of ICB to treat HRD tumors has clinical implications. Our group has previously shown a signature of four chemokines associates with a T cell-inflamed phenotype in pancreatic cancer, but it remains unknown whether this association holds in other tumors, and how HRD tumors fall on this immune spectrum. Using matched genomic and transcriptomic data from TCGA, we sought to investigate whether the four-chemokine signature predicted a T cell-inflamed phenotype in 158 treatment-naïve primary ovarian cancers, another tumor type with poor survival and low response rates to ICB attributed in part to a lack of T cell-inflammation. As in pancreatic cancer, 4-chemokinehi tumors displayed a phenotype suggesting proper mounting of the cancer-immunity cycle, including increased expression of innate immune signaling pathways implicated in mediating T cell-inflammation in tumors, antigen presenting and T cell activation and inhibition, MHC I presentation, cytolytic activity, PDL1 and CTLA4 expression, and signatures predictive of response to ICB. Interestingly, tumors with COSMIC signature 3, predictive of HRD had increased expression of gene signatures associated with T cell-inflammation, including increased expression of the 4-chemokine signature. Taken together, these results further validate the 4-chemokine signature at predicting T cell-inflammation and suggest similar mechanisms driving T cell-inflammation remain consistent across different tumor types. Moreover, these data further suggest that homologous recombination repair deficiency may predispose tumors to a favourable milieu amenable to immunotherapies requiring T cell-inflammation. Understanding mediators of T cell-inflammation, both at cellular and genomic resolutions, may lead to improved predictors of response to current and novel immunotherapies and in turn improved patient outcomes for patients suffering from these diseases. Citation Format: Joan Miguel Romero, Alain Pacis, Rob E. Denroche, Gun Ho Jang, Barbara Grünwald, Yifan Wang, Steven Gallinger, George Zogopoulos. Tumors with homologous recombination repair deficiency signatures associate with an RNAseq profile profile suggestive of T cell-inflammation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1485.

Purpose: The molecular drivers of antitumor immunity in pancreatic ductal adenocarcinoma (PDAC) are poorly understood, posing a major obstacle for the identification of patients potentially amenable for immune-checkpoint blockade or other novel strategies. Here, we explore the association of chemokine expression with effector T-cell infiltration in PDAC. Experimental Design: Discovery cohorts comprised 113 primary resected PDAC and 107 PDAC liver metastases. Validation cohorts comprised 182 PDAC from The Cancer Genome Atlas and 92 PDACs from the Australian International Cancer Genome Consortium. We explored associations between immune cell counts by immunohistochemistry, chemokine expression, and transcriptional hallmarks of antitumor immunity by RNA sequencing (RNA-seq), and mutational burden by whole-genome sequencing. Results: Among all known human chemokines, a coregulated set of four (CCL4, CCL5, CXCL9, and CXCL10) was strongly associated with CD8+ T-cell infiltration (P < 0.001). Expression of this “4-chemokine signature” positively correlated with transcriptional metrics of T-cell activation (ZAP70, ITK, and IL2RB), cytolytic activity (GZMA and PRF1), and immunosuppression (PDL1, PD1, CTLA4, TIM3, TIGIT, LAG3, FASLG, and IDO1). Furthermore, the 4-chemokine signature marked tumors with increased T-cell activation scores (MHC I presentation, T-cell/APC costimulation) and elevated expression of innate immune sensing pathways involved in T-cell priming (STING and NLRP3 inflammasome pathways, BATF3-driven dendritic cells). Importantly, expression of this 4-chemokine signature was consistently indicative of a T-cell–inflamed phenotype across primary PDAC and PDAC liver metastases. Conclusions: A conserved 4-chemokine signature marks resectable and metastatic PDAC tumors with an active antitumor phenotype. This could have implications for the appropriate selection of PDAC patients in immunotherapy trials.

2546 Background: Treatment responses to immune checkpoint blockade (ICB) associate with T cell tumor inflammation. Tumors with mismatch repair deficiency display an inflammatory tumor phenotype and respond to ICB. Similarly, tumors with homologous recombination repair deficiency (HR-d) may be primed for ICB treatment. We have previously shown that a panel of 4 chemokines identifies a subclass of pancreatic cancer with markers of T cell-inflammation. Here, we evaluated this 4-chemokine signature in cancer types with HR-d molecular subclasses. Methods: We combined paired transcriptomes and genomic data of breast (n = 699), ovarian (n = 174) and prostate (n = 457) cancers from the Cancer Genome Atlas and tumor-enriched pancreas cancers (n = 121) to evaluate the 4-chemokine signature in HR-d vs. HR-proficient tumors across these 4 cancers. Metrics of antitumor immunity were also compared. Results: Across tumor types, elevated expression of the 4-chemokine signature (chemokine-hi) associated with transcriptional hallmarks of a T cell-mediated antitumor response, including antigen presenting cell stimulation, antigen presentation, and T cell activity. In tumors with a predominant COSMIC signature 3, which associates with HR-d, the 4-chemokine signature predicted intermediate levels of T cell-inflammation. Conclusions: These data suggest that 1) the 4-chemokine signature may be a clinically relevant biomarker in identifying subclasses of tumours responsive to immunotherapies, and that 2) HR-d tumors harbor intermediate immunogenicity. Correlation of treatment responses to immunotherapies with the 4-chemokine signature is needed validate its predictive value as a biomarker for treatment stratification with immunotherapies.[Table: see text]

Pancreatic ductal adenocarcinoma (PDAC) remains mostly untreatable while its incidence is on the rise. PDAC stroma should be a reservoir for novel therapeutic targets. Yet, stromal cellular complexity and an extensive intratumoral heterogeneity in human patients have left the functions of PDAC stroma poorly understood and likely hamper its targeting. Here, we set out to deconvolute regional heterogeneity in human PDAC stroma and assess its role in disease progression. Using resected & advanced biospecimens with known patient outcome, we mapped the stromal and epithelial landscapes of PDAC by combining integrative histopathology, quantitative image analysis of a 30-marker IHC panel, genomics and proteomics, machine learning, scRNAseq of PDAC-derived fibroblasts, and controlled functional assays. This histology-guided multidimensional approach revealed two overarching types of sub-tumormicroenvironments (subTMEs) in PDAC, present across stages and primary and metastatic sites. These subTMEs co-occurred intratumourally but were spatially confined, producing patient-specific cellular and molecular heterogeneity in PDAC stroma. SubTME-resolved IHC characterization of PDAC specimens and multiplexed functional analyses with subTME-specific patient-derived fibroblasts and organoids then identified how both microenvironmental programs were uniquely structured to support crucial aspects of tumour biology. Forming a complementary stromal support system, reactive subTME regions rich in fibroblasts and immune cells were vascularized and promoted features of aggressive tumour progression, while protective subTME regions enriched in ECM supported tumour differentiation yet were markedly chemoprotective and translated into poor treatment response during 1st line chemotherapy. Consequently, tumours benefited from concomitant presence of both subTMEs and patients with phenotypically heterogenous stroma displayed shortened survival. Our patient-matched multidimensional data were then used to train a Random Forest model for prediction of subTME presence from bulk RNAseq samples. This again stratified PDAC patients in the independent TCGA cohort into distinct clinical outcomes by stromal phenotypic heterogeneity. In conclusion, we have delineated human PDAC stroma to subtype its heterogeneity into phenotypically distinct reactive and protective elements. This defines the active role of two overarching sub-microenvironment types in PDAC progression and sets a path towards developing novel stroma-instructed therapies. Citation Format: Barbara T. Grünwald, Antoine Devisme, Foram Vyas, Geoffroy Andrieux, Gun Ho Jang, Kazeera Aliar, Curtis McCloskey, Andrew Macklin, Joan Miguel Romero, Laura Tamblyn, Nikolina Radulovich, Peter Bronsert, Grainne O’Kane, Julie Wilson, Jennifer Knox, Sandra Fischer, Thomas Kislinger, Melanie Boerries, Steven Gallinger, Rama Khokha. Stromal phenotypic heterogeneity fosters pancreatic cancer progression [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr PR-002.

We integrated clinical, genomic and transcriptomic data from 217 primaries and 101 metastases from 289 patients to characterize progression of pancreatic ductal adenocarcinoma. Driver genes alterations, mutational and expression-based signatures were mostly preserved, and discordances implied Halstedian tumour spread. Cell cycle progression increased with sequential inactivation of tumour suppressors, yet remained higher in metastases, perhaps driven by cell cycle regulatory gene mutations. Half of the cases were hypoxic by expression markers, overlapping with molecular subtypes. Inter-tumoural heterogeneity showed conserved truncations, inversions and translocations and therefore likely driver events. Multiple synchronous and metachronous PDAC arising in the same patients were actually intra-parenchymal metastases, and not independent primary tumours. Established clinical co-variates dominated survival analyses, though cell cycle progression, hypoxia and inter-tumoural heterogeneity may inform clinical practice.

Pancreatic cancer continues to have the highest mortality rate of all solid cancers, with a 5-year overall survival of approximately 8%. Despite recent progress in other malignancies, immunotherapy remains ineffective against pancreatic cancer. Previous work from our group and others has shown that tumors with mismatch repair (MMR) and homologous repair (HR) deficiency have increased immune activity, likely attributable to the inherently increased mutational and neoantigen load in these patients. However, there remains a subset of pancreatic cancer patients with increased CD8+ T cell infiltration, despite lacking these specific mutational signatures. Furthermore, an increasing body of evidence has shown that mutational burden and neoantigen load only partially explain the T cell-inflamed phenotype seen in tumors, implicating the presence of additional mechanisms that drive T cell infiltration in cancer. Several recent studies have highlighted the importance of proper CD8+ T cell priming by antigen presenting cells (APCs), particularly Batf3+ dendritic cells (DCs), and subsequent tumor infiltration via chemokines for immunotherapy to be effective. In this study, we investigated the involvement of chemokines in cytotoxic T lymphocyte infiltration in pancreatic cancer. Using a bioinformatics-driven approach, we analyzed 78 treatment-naïve, primary pancreas cancer resections for associations between CD8+ tumour infiltrating lymphocytes (TILs) and chemokine expression by RNAseq. A panel of chemokines, including CCL4, CCL5, CXCL9, CXCL10, and CXCL11, was highly associated with CD8+ TILs (p < 0.001). Segregating 173 tumour-enriched patient RNAseq samples based on expression of CXCL9 and CXCL10, we found those with higher expression of these chemokines had increased immune activation signatures. Importantly, this included increased MHC I presentation, presence of Batf3+ DCs, and T cell/APC co-stimulation (p < 0.001), while we observed no differences in conventional predictors of CD8+ T cell infiltration such as SNV counts or neoantigens between groups. These results were consistent across ICGC and TCGA data sets. Moreover, these results were also recapitulated in 72 tumor-enriched liver metastases, suggesting an underlying immunobiology that may occur in both primary and metastatic sites. The cellular sources of these chemokines, as determined by immunohistochemical analysis, and the role of tumor-sensing innate immune pathways leading to CD8+ T cell priming, by pathway and differential gene expression analysis, are currently being investigated. Taken together, these results demonstrate a potential role for these chemokines in recruiting CD8+ T cells in pancreatic cancer. Understanding mediators driving cytotoxic T cell infiltration will help identify mechanisms leading to proper CD8+ T cell priming and homing into tumors, to stratify patients amenable for known and novel immunotherapies. Citation Format: Joan Miguel Romero, Barbara Grünwald, Ashton Connor, Gun Ho Jang, Prashant Bavi, Aaditeya Jhaveri, Mehdi Masoomian, Sandra Fischer, Amy Zhang, Robert E. Denroche, Tracy McGaha, Faiyaz Notta, Pamela Ohashi, Grainne O'Kane, Julie Wilson, Jennifer Knox, Steven Gallinger. Mediators of CD8+ cytotoxic T lymphocyte infiltration in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1500.

We integrated clinical, genomic, and transcriptomic data from 224 primaries and 95 metastases from 289 patients to characterize progression of pancreatic ductal adenocarcinoma (PDAC). Driver gene alterations and mutational and expression-based signatures were preserved, with truncations, inversions, and translocations most conserved. Cell cycle progression (CCP) increased with sequential inactivation of tumor suppressors, yet remained higher in metastases, perhaps driven by cell cycle regulatory gene variants. Half of the cases were hypoxic by expression markers, overlapping with molecular subtypes. Paired tumor heterogeneity showed cancer cell migration by Halstedian progression. Multiple PDACs arising synchronously and metachronously in the same pancreas were actually intra-parenchymal metastases, not independent primary tumors. Established clinical co-variates dominated survival analyses, although CCP and hypoxia may inform clinical practice.