Figure S1 shows analysis of the abundance of unique T-cell clones in blood at baseline compared to after treatment.

Table S2 shows abscopal effects in a single non-injected lesion by percent change from baseline, as well as the location of the lesion.

Table S1 shows dosing schedule and drug-related treatment-emergent adverse events occurring in at least 10% of patients in this study.

Adjunction of immune response into the TNM classification system improves the prediction of colon cancer (CC) prognosis. However, immune response measurements have not been used as robust biomarkers of pathology in clinical practice until the introduction of Immunoscore (IS), a standardized assay based on automated artificial intelligence assisted digital pathology. The strong prognostic impact of the immune response, as assessed by IS, has been widely validated and IS can help to refine treatment decision making in early CC. In this study, we compared pathologist visual scoring to IS. Four pathologists evaluated tumor specimens from 50 early-stage CC patients and classified the CD3+ and CD8+ T-cell densities at the tumor site (T-score) into 2 (High/Low) categories. Individual and overall pathologist scoring of immune response (before and after training for immune response assessment) were compared to the reference IS (High/Low). Pathologists’ disagreement with the reference IS was observed in almost half of the cases (48%) and training only slightly improved the accuracy of pathologists’ classification. Agreement among pathologists was minimal with a Kappa of 0.34 and 0.57 before and after training, respectively. The standardized IS assay outperformed expert pathologist assessment in the clinical setting.

Abstract Purpose: LTX-315 is a first-in-class, 9-mer membranolytic peptide that has shown potent immunomodulatory properties in preclinical models. We conducted a phase I dose-escalating study of intratumoral LTX-315 administration in patients with advanced solid tumors. Patients and Methods: Thirty-nine patients were enrolled, receiving LTX-315 injections into accessible tumors. The primary objective was to assess the safety and tolerability of this approach, with antitumor and immunomodulatory activity as secondary objectives. Tumor biopsies were collected at baseline and posttreatment for analysis of immunologic parameters. Results: The most common treatment-related grade 1–2 adverse events were vascular disorders including transient hypotension (18 patients, 46%), flushing (11 patients, 28%), and injection site reactions in 38% of patients. The most common grade 3 LTX-315–related toxicities were hypersensitivity or anaphylaxis (4 patients, 10%). Analysis of immune endpoints in serial biopsies indicated that LTX-315 induces necrosis and CD8+ T-cell infiltration into the tumor microenvironment. Sequencing of the T-cell receptor repertoire in peripheral blood identified significant expansion of T-cell clones after treatment, of which 49% were present in available tumor biopsies after treatment, suggesting that they were tumor associated. Substantial volume reduction (≥30%) of injected tumors occurred in 29% of the patients, and 86% (12/14 biopsies) had an increase in intralesional CD8+ T cells posttreatment. No partial responses by immune-related response criteria were seen, but evidence of abscopal effect was demonstrated following treatment with LTX-315. Conclusions: LTX-315 has an acceptable safety profile, is clinically active, induces changes in the tumor microenvironment and contributes to immune-mediated anticancer activity.

4105 Background: Risk assessment is particularly important to decide when to propose an adjuvant treatment for Stage II Colon Cancer (CC) patients. However, the current tumor risk features are imperfect and additional risk factors are needed to guide treatment decisions. The consensus Immunoscore is an alternative and powerful approach that could be used in the T4N0 Stage II colon cancer population. Immunoscore is an in vitro diagnostic test that predicts the risk of relapse in patients with CC by measuring the host immune response at the tumor site. Methods: From the international Immunoscore consortium study (n = 2681) (Pagès et al. The Lancet 2018), a subgroup analysis was performed on T4N0 Stage II colon cancer patients (n = 208). Results: In stage II T4N0, Int+Hi Immunoscore represented 65.4% of the population and low-Immunoscore only 34.6%. T4N0 patients with Int+Hi Immunoscore presented a significantly prolonged survival for TTR compared to low Immunoscore patients (5 years recurrence rate Int+Hi: 84.6% (78.3-91.5), Lo: 46.3% (35.1-61); unadjusted HR [Int+Hi vs Lo] = 0.21; (95% CI 0.11-0.4); P< 0.0001), representing a restricted mean survival time (RMST) difference of 80.9 months (95% CI 51.1-110.6) ( P< 0.0001). The DFS was significantly different between Int+Hi and Low Immunoscore (5 years recurrence rate Int+Hi: 70.5% (95% CI 62.7-79.1), Lo: 38.5% (95% CI 28.2-52.5); unadjusted HR [Int+Hi vs Lo] = 0.31; (95% CI 0.19-0.49); P< 0.0001). Using restricted mean survival time (RMST) a significant ( P< 0.0001) difference of 60.4 months (95% CI 32.6-88.1) was observed between the 2 groups Importantly, Cox multivariate analysis in Stage II T4N0 colon cancer patients, revealed that Immunoscore was the only remaining significant parameter (HR [Int+Hi vs Lo] = 0.15; (95% CI 0.05-0.46); P= 0.0009). In contrast, all other parameters, gender, sidedness, mucinous, grade, T-stage, VELIPI, MSI were not significant in multivariate analysis. Finally, Immunoscore showed the highest relative contribution to predict relapse (76.2% chi2 relative contribution), stronger than all the other parameters, MSI (16.1%), Grade (5%), sidedness (2%), gender (2%), VELIPI (1%). Conclusions: Immunoscore is the most powerful parameter to predict the risk in T4N0 population, and could be a good tool for adjuvant treatment decision in Stage II patients.

Genetic dynamics underlying cancer progression are largely unknown and several genes involved in highly prevalent illnesses (e.g., hypertension, obesity, and diabetes) strongly concur to cancer phenotype heterogeneity. To study genotype-phenotype relationships contributing to the mutational evolution of colorectal cancer (CRC) with a focus on liver metastases, we performed genome profiling on tumor tissues of CRC patients with liver metastatic disease and no co-morbidities. We studied 523 cancer-related genes and tumor-immune microenvironment characteristics in primary and matched metastatic tissues. We observed a loss of KRAS and SMAD4 alterations and a high granzyme-B+ T-cell infiltration when the disease did not progress. Conversely, gain in KRAS, PIK3CA and SMAD4 alterations and scarce granzyme-B+ T-cells infiltration were observed when the tumor evolved towards a poly-metastatic spread. These findings provide novel insights into the identification of tumor oligo-metastatic status, indicating that some genes are on a boundary line between these two clinical settings (oligo- vs. poly-metastatic CRC). We speculate that the identification of these genes and modification of their evolution could be a new approach for anti-cancer therapeutic strategies.

Genetics and immunologic dynamics pushing the evolution of colorectal cancer (CRC) from the primary tumor to the metastases are largely unknown; cancer heterogeneity makes challenging both therapy and mechanistic studies. We selected patients developing CRC with lung-limited metastatic disease as only illness during their life in order to find any relevant genotype-phenotype relationship. Analysis of 523 cancer-relevant genes and of immune cells infiltration in primary and metastatic tissues revealed atypical genomic trajectories (TMB decrease, KRAS and SMAD4 regressive mutations), specific genetic events (ERBB2 point mutations) and scarce T-cell infiltration. These insights provide novel information in oligometastatic CRC biology and new perspectives for cancer monitoring and anti-cancer therapeutic strategies.

Background: The American Joint Committee on Cancer staging and other prognostic tools fail to account for stage-independent variability in outcome. We developed a prognostic classifier adding Immunoscore to clinicopathological and molecular features in patients with stage III colon cancer. Methods: Patient (n = 559) data from the FOLFOX arm of adjuvant trial NCCTG N0147 were used to construct Cox models for predicting disease-free survival (DFS). Variables included age, sex, T stage, positive lymph nodes (thornLNs), N stage, performance status, histologic grade, sidedness, KRAS/BRAF, mismatch repair, and Immunoscore (CD3(+), CD8(+) T-cell densities). After determining optimal functional form (continuous or categorical) and within Cox models, backward selection was performed to analyze all variables as candidate predictors. All statistical tests were two-sided. Results: Poorer DFS was found for tumors that were T4 vs T3 (hazard ratio [HR] = 1.76, 95% confidence interval [CI] = 1.19 to 2.60; P =.004), right- vs left-sided (HR = 1.52, 95% CI = 1.14 to 2.04; P =.005), BRAF V600E (HR = 1.74, 95% CI = 1.26 to 2.40; P<.001), mutant KRAS (HR = 1.66, 95% CI = 1.08 to 2.55; P =.02), and low vs high Immunoscore (HR = 1.69, 95% CI = 1.22 to 2.33; P =.001) (all P<.02). Increasing numbers of +LNs and lower continuous Immunoscore were associated with poorer DFS that achieved significance (both Ps<.0001). After number of +LNs, T stage, and BRAF/KRAS, Immunoscore was the most informative predictor of DFS shown multivariately. Among T1- 3 N-1 tumors, Immunoscore was the only variable associated with DFS that achieved statistical significance. A nomogram was generated to determine the likelihood of being recurrence-free at 3 years. Conclusions: The Immunoscore can enhance the accuracy of survival prediction among patients with stage III colon cancer.

Background New and fully validated tests need to be brought into clinical practice to improve the estimation of recurrence risk in patients with colon cancer. The aim of this study was to assess the analytical performances of the Immunoscore (IS) and show its contribution to prognosis prediction. Methods Immunohistochemical staining of CD3+ and CD8+ T cells on adjacent sections of colon cancer tissues were quantified in the core of the tumor and its invasive margin with dedicated IS modules integrated into digital pathology software. Staining intensity across samples collected between 1989 and 2016 (n=595) was measured. The accuracy of the IS workflow was established by comparing optical and automatic counts. Analytical precision of the IS was evaluated within individual tumor block on distant sections and between eligible blocks. The IS interlaboratory reproducibility (n=100) and overall assay precision were assessed (n=3). Contribution of the IS to prediction of recurrence based on clinical and molecular parameters was determined (n=538). Results Optical and automatic counts for CD3+ or CD8+ were strongly correlated (r=0.94, p<0.001 and r=0.92, p<0.001, respectively). CD3 and CD8 staining intensities were not altered by the age of the tumor block over a period of 30 years. Neither the position of tested tissue sections within a tumor block nor the selection of the tissue blocks affected the IS. Reproducibility of the IS was not affected by multiple variables (eg, antibody lots, DAB revelation kits, immunohistochemistry automates and operators). Interassay repeatability of the IS was 100% and interlaboratory reproducibility between two testing centers was 93%. Finally, in a case series of patients with stage II–III colon cancer, the relative proportion of variance for time to recurrence was greatest for the IS (53% of prognostic variability) in a model that included IS, T-stage, microsatellite instability status and total number of lymph nodes. Conclusion IS is a robust and validated clinical assay leveraging immune scoring to predict recurrence risk of patient with localized colon cancer. The strong and independent prognostic value of IS should pave the way for it use in clinical practice.

3513 Background: The Immunoscore (IS), which has been shown to prognostically classify Stage I-III colon cancer (CC) patients, was assessed in the IDEA France cohort study evaluating 3 versus 6 months of oxaliplatin-based adjuvant chemotherapy in Stage III CC patients. Methods: Densities of CD3+ and cytotoxic CD8+ T cells in the tumor and invasive margin of each patient were quantified by digital pathology and converted to IS using pre-defined published cut-off. The performance of IS to predict disease-free survival (DFS) was assessed in the modified intention-to-treat population, in each study arm, and was adjusted with relevant clinical features in multivariable Cox models. Harrell’s C-statistics was used to investigate the IS performance. Results: 1322 patients were included; 82 were excluded due to pre-analytical non-conformity. IS was successfully analyzed in 1062 (85.6%) eligible patients. In a 2-category IS analysis, Low and (Int+High) IS were observed in n=599 (43.6%) and n=463 (56.4%) patients, respectively. IS was significantly correlated with T stage, T/N stage (T1-3 and N1 versus T4 and/or N2), and microsatellite instability status. The study met its primary objective of validating that Low IS identifies patients with higher-risk of relapse or death [HR=1.54; 95%CI 1.24-1.93, p=0.0001]. The 3-year DFS rates were 66.80% [95%CI 62.23-70.95] and 77.14% [95%CI 73.50-80.35] for Low IS and (Int+High) IS, respectively. In multivariable analysis, IS remained independently associated with DFS (p<0.0012) when combined with T/N stage. The addition of IS to the T/N stage significantly improved the model discrimination capacity [bootstrap C index mean difference, 0.022; 95%CI 0.005-0.04]. In addition, IS in 3 categories (Low, Int, High) and as a continuous variable were also both significantly associated with DFS (all p<0.001). In univariable analysis, IS was also associated with DFS in 6 months arm (p<0.0001); a similar trend was observed in 3 months arm (p=0.09). Conclusions: IS was confirmed as a prognostic factor of DFS in Stage III CC patients in the prospective IDEA France cohort study. Clinical trial information: NCT03422601.

487 Background: Immunoscore Colon is an IVD test predicting the risk of relapse in early-stage colon cancer (CC) patients, by measuring the host immune response at the tumor site. It is a risk-assessment tool providing independent and superior prognostic value than the usual tumor risk parameters and is intended to be used as an adjunct to the TNM classification. Risk assessment is particularly important to decide when to propose an adjuvant (adj.) treatment for stage (St) II CC patients. High-risk stage II patients defined as those with poor prognostic features including T4, lymph nodes < 12, poor differentiation, VELIPI, bowel obstruction/perforation can be considered for adj. chemotherapy (CT). However, additional risk factors are needed to guide treatment decisions. Methods: A subgroup analysis was performed on the St II untreated patients (n = 1130) from the Immunoscore international validation study (Pagès The Lancet 2018). The high-risk patients (with at least 1 clinico-pathological high-risk feature) were classified in 2 categories using pre-defined cutoffs: Low Immunoscore versus High Immunoscore and their five-year time to recurrence (5Y TTR) was compared to the TTR of the low-risk patients (without any clinico-pathological high-risk feature). Results: Among the patients with high-risk features (n = 630), 438 (69.5%) had a High Immunoscore with a corresponding 5Y TTR of 87.4 (95% CI 83.9-91.0), statistically similar (logrank pv not stratified p > 0.42, wald pv stratified by center p > 0.20) to the TTR 89.1 (95% CI 86.1-92.1) observed for the 500 low-risk patients (with no clinico-pathological feature). Furthermore, 5Y TTR for these patients were statistically similar to those of St II patients with high-risk features and a High Immunoscore (n = 438), who received adj. CT (n = 162) (5Y TTR of 83.4 (95% CI 77.6-89.9). Conclusions: These data show that despite the presence of high-risk features that usually trigger adj. treatment, when not treated with CT, a significant part of these patients (69.5%) have a recurrence risk similar to the low risk patients. Therefore, the Immunoscore test could be a good tool for adj. treatment decision in St II patients.

Colorectal cancer can be categorized into two major molecular subtypes according to the status of their DNA proofreading and repair machinery. The DNA repair status of tumor cells plays a major role in shaping the immune landscape of tumors and in determining the clinical response of colorectal cancer patients to immune checkpoint blockade therapies. Colorectal cancers that develop in a context of DNA mismatch repair or polymerase proofreading deficiency are generally conspicuously infiltrated by effector memory T cells and are associated with an improved clinical prognosis relative to their replication repair-proficient counterpart. While mismatch repair-deficient colorectal cancers, and most likely POLE and POLD1-mutated cancers, are amenable to immune checkpoint blockade therapies, the promise of immunotherapy still remains unfulfilled for for the majority of colorectal cancer patients. This review focusses on the role of the immune system in the tumorigenesis and clinical behavior of colorectal cancer. Furthermore, we discuss how latest advances in the fields of genomics and oncoimmunology may pave the way to broaden the scope of immunotherapy for this disease.

Colorectal cancer can be categorized into two major molecular subtypes according to the status of their DNA proofreading and repair machinery. The DNA repair status of tumor cells plays a major role in shaping the immune landscape of tumors and in determining the clinical response of colorectal cancer patients to immune checkpoint blockade therapies. Colorectal cancers that develop in a context of DNA mismatch repair or polymerase proofreading deficiency are generally conspicuously infiltrated by effector memory T cells and are associated with an improved clinical prognosis relative to their replication repair-proficient counterpart. While mismatch repair-deficient colorectal cancers, and most likely POLE and POLD1-mutated cancers, are amenable to immune checkpoint blockade therapies, the promise of immunotherapy still remains unfulfilled for for the majority of colorectal cancer patients. This review focusses on the role of the immune system in the tumorigenesis and clinical behavior of colorectal cancer. Furthermore, we discuss how latest advances in the fields of genomics and oncoimmunology may pave the way to broaden the scope of immunotherapy for this disease.

Background: LTX-315 is a first-in class oncolytic peptide that has the ability to kill cancer cells and induce specific anticancer immune response when injected locally into experimental tumors established in immunocompetent mice. The underlying mechanism of action include induction of immunogenic cell death with subsequent infiltration of T-cells into the tumor microenvironment. A multicenter Phase I study was conducted to evaluate the safety and tolerability of LTX-315 in patients with solid tumors who had exhausted standard treatment options. Methods: The primary objective of the trial was to assess the safety and tolerability of multiple, intratumoral doses of LTX-315 as a monotherapy. The secondary objective was to evaluate clinical activity (assessed using immune-related response criteria (irRC)) and the ability of LTX-315 to evoke local and systemic immune responses. Paired pre and post treatment tumor samples were obtained throughout the study. Immunohistochemistry and gene expression analysis were performed on these paired tumor biopsies. T-cell receptor (TCR) repertoire in peripheral blood and tumor biopsies was assessed by TCRβ-gene sequencing. Results: Twenty-seven patients were treated with LTX-315 monotherapy and had at least one post baseline efficacy assessment, of which 5 patients had the diagnosis of sarcoma. Best overall response seen in the sarcoma patients was SD in 4 out of 5 patients (80%). In one patient, a marked tumor regression was observed in two distant non-injected lesions (39% and 66% reduction). All patients experienced a treatment emergent adverse event (TEAE) and all patients experienced at least one episode of LTX-315 related adverse event, most commonly an acute reaction to injection of LTX-315 such as hypotension, rash, flushing or itching. The majority (94%) of these injection-related events were grade 1. There were 2 episodes (6%) of grade 3 AE, no serious adverse events were reported. Enhanced tumor infiltration of CD3+ and CD8+T cells, assessed by immunoscore®, was observed in 100% and 75% of the responding sarcoma patients, respectively. Gene expression profiling by Immunosign ®21 in one injected lesion showed a distinct “cold to hot’’ signature change.TCR sequencing of the patient`s T cells in peripheral blood revealed significant clonal expansion of T-cells, 39% of these T cell clones were also detected in post-treatment biopsied tumors. Conclusions: Intratumoral LTX-315 is generally safe and tolerable. LTX-315 monotherapy enhances TIL population and induces polyclonal T-cell responses Based on the data from the Phase I study, the dosing regimen of LTX-315 will be assessed and optimized to position LTX-315 as a therapeutic agent in combination with other targeted immune therapies such as checkpoint inhibitors to address an unmet need in a select group of indications. Registration number; NCT01986426 Citation Format: Jean-Francois Baaurain, Christiane Jungels, Rebecca S. Kristeleit, Dag E. Jossang, Nina L. Jebsen, Øystein Rekdal, Baldur Sveinbjornsson, Vibeke S. Gjerstad, Paal Brunsvig, Jerome Galon, Fabienne Hermitte, Hamina Patel. A phase I study of the oncolytic peptide LTX-315 generatesde novoT-cell responses and clinical benefit in patients with advanced sarcoma [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 CT010.

614 Background: A consensus interpretation of the IDEA colon cancer study results suggested that risk categories based on T/N stage grouping be used to guide decision-making for duration (3 vs 6 months) of adjuvant FOLFOX or CapeOX chemotherapy. Given the prognostic potential of immune biomarkers, we examined the immunoscore and individual T and B lymphocyte markers in low and high risk T/N subsets of stage III colon carcinoma patients (N=600) treated with adjuvant FOLFOX. Methods: Immunoscore (CD3+, CD8+) and individual T-cell and CD20+ B-cell immunostain densities in central tumor (CT) and invasive margin (IM) of FFPE sections were quantified by image analysis. A predetermined immunoscore categorization was used [high (2-4) vs low (0-1)]. Individual markers were analyzed by backwards selection wherein CD3+ IM was most robust for prognosis and an optimized cutoff was then determined. Associations with disease-free survival (DFS) were analyzed by multivariable Cox regression adjusting for age, T/N stage, sidedness, KRAS/BRAF, and DNA mismatch repair. Results: In low and high risk T/N patient subsets, the immunoscore and CD3+ IM were each significantly discriminant for prognosis. Among low risk (T1-3N1) patients, a high vs low immunoscore was associated with a 91% vs 77% 3-year DFS [HR 0.57, 95% confidence interval (CI) 0.34-0.95, adjusted (adj) P= 0.026]. Among high risk (T4 or N2) patients, a high vs low immunoscore was associated with a 68% vs 54% 3-year DFS (HR 0.64, 95% CI 0.42-0.98, Padj= 0.034]. Similarly, a high vs low intratumoral CD3+ density at the invasive margin (IM) was significantly associated with prognosis in low risk [HR 0.37, 95% CI 0.21- 0.66), Padj< 0.0003] and in high risk [HR 0.47, 95% CI, 0.27- 0.80), Padj< 0.0028] patient subsets. Conclusions: Immunoscore and CD3+ IM were shown to prognostically stratify FOLFOX-treated patients within both low and high risk T/N subsets. These data underscore limitations of the T/N risk classification for adjuvant treatment decisions in stage III patients, and demonstrate the ability of T-cell markers to enhance prognostication to guide clinical decision-making.

Soft tissue sarcoma (STS) is a rare type of cancer, which occurs in tissues connecting, supporting and/or surrounding other structures of the body, like muscle, fat, etc. More than 50 subtypes of STS exist, characterized by a strong propensity to local recurrence and metastatic spreading. Consistently, the immune microenvironment in sarcomas is highly variable. A new class of high electron density material, hafnium oxide, was designed at the nanoscale to efficiently absorb ionizing radiation from within the tumor cells and increase the dose deposition into the tumor. These nanoparticles (HfO2-NP), delivered into the tumor by a single injection and activated by radiotherapy, have the ability to enhance immunogenic cell death and immune response in preclinical studies. Here, we explore in a phase II/III trial in patients with locally advanced STS, the effects of nanosized hafnium oxide exposed to RT in terms of tumor immune profile changes in patients, when compared to RT alone. Patients with locally advanced STS (NCT02379845) received either HfO2-NP activated by RT or RT alone. Pre- and post-treatment (biopsy and resection, respectively) tumor tissues for each patient were analyzed by immunohistochemistry and Digital Pathology for immune biomarkers (CD8+, CD3+, PD1+, CD103+) and Pan-Immune gene expression profiling by NanoString (>16 patients per arm). Immunohistochemistry analysis (post- vs pre-treatment) show a marked increase of the tested biomarkers for patient treated with HfO2-NP + RT, particularly for CD8+ and PD1, while no differences are seen for RT alone. Interestingly, the profile of gene expression HfO2-NP + RT differs from those obtained with RT alone. Functional analysis of genes expression up-regulated in HfO2-NP + RT (post- vs pre-treatment) shows an increase of the cytokine/interleukin and immune checkpoints expression, and T cell lymphocyte activation markers, compared to RT alone. Regarding immune cells infiltrates (post- vs pre-treatment), promising results are reported for patients treated with HfO2-NP activated by RT, when compared to RT. So far, these results show that HfO2-NP + RT induces a specific adaptive immune pattern. As such, it may convert immunologically “cold” tumor into “hot” tumor and be effectively combined with immunotherapeutic agents across oncology. More tissue samples are under evaluation to reinforce these findings.

Background: Tumor infiltrating lymphocytes (TIL) indicate a host anti-tumor immune response that may influence patient (pt) survival. Immunoscore was developed using CD3+ and CD8+ density and location in primary colon cancer (CC) pts with pooled stages, varying treatment and follow-up. We determined if individual immune markers and/or Immunoscore are prognostic in resected stage III CC pts (N = 600) from the FOLFOX arm of a phase IIII trial. Methods: T (CD3+, CD8+) and B (CD20+) lymphocyte marker density in central tumor (CT) and invasive margin (IM) were evaluated by immunostaining and quantified by image analysis. Immunoscore was calculated on a scale of 0-4 with high densities of CD3+ and CD8+ in both CT and IM scored as 2-4; low densities as 0-1. Associations with disease-free survival (DFS) were evaluated by multivariable Cox regression adjusting for age, T/N stage, sidedness, KRAS/BRAF, DNA mismatch repair (MMR). Results: Data for CD3+, CD8+ and CD20+ were generated (N = 595). Higher density of CD3+ CT, CD3+ IM and CD8+ IM were significantly associated with longer DFS adjusting for covariates. CD3+ IM had the strongest association with DFS that was also shown using an optimized cutoff [HR 0.46 (95% CI,.31,.67), p < 0.0001]. Using a prior Immunoscore risk stratification, higher scores were associated with better DFS [HR 0.62 (CI,.45,.86), p = 0.0030]. HRs for CD3+ IM and Immunoscore remained very similar after excluding dMMR pts. In pt subsets of T1-3N1 and T4 or N2 tumors, higher CD3+ IM [T1-3N1: HR 0.37 (CI,.21,.66), p < 0.0003; T4 or N2: HR 0.47 (CI,.27,.80), p < 0.0028] and Immunoscore were both significantly prognostic. Conclusions: Densities of CD3+ and CD8+, especially at IM, and Immunoscore can prognostically stratify FOLFOX-treated stage III CC pts. The prognostic impact remained statistically significantly after excluding deficient MMR tumors, and also in T1-3N1 and T4 or N2 pt subsets. Our results provide validation for Immunoscore in a clinical trial cohort.

e14615 Background: NBTXR3 are functionalized hafnium oxide nanoparticles, undergoing seven clinical trials for enhancing radiation therapy (RT). The high electron density of the nanoparticles, when exposed to radiotherapy (NBTXR3 + RT), allow absorption/deposition of a high radiation dose within the cancer cells to physically kill the cells, and possibly improve outcome. Besides, NBTXR3 + RT has shown subsequent ability to enhance immunogenic cell death and immune response in preclinics. We hypothesized that NBTXR3 + RT could trigger an enhanced immune response when compared to RT in patients with STS. Methods: Tumor tissues pre- (biopsy) and/or post-treatment (resection) were collected from patients (pts) with locally advanced STS, who received either NBTXR3 as intratumor injection and RT (14 pts) or RT (12 pts), as preoperative treatment (NCT02379845). Immunohistochemistry and Digital Pathology for immune biomarkers and for Immunoscore (CD3/CD8) were analyzed. Gene expression profiling and pre-optimized immune-gene signatures called Immunosign were also used. Results: A significant increase of T cells (CD3+, CD8+) and a marked increase of CD103+ immune cell infiltration post- vs pre-treatment were observed for NBTXR3 + RT ( P< 0.01), while no differences were seen for RT. Post-treatment, an increased Immunoscore (CD3 + CD8 cell densities) was observed for NBTXR3 + RT compared to RT (P < 0.07). Consistently, the up-regulation of pan immune genes expression and specifically expression of adaptive immunity genes between pre- and post-treatment, was pronounced for NBTXR3 + RT when compared to RT. Functional analysis of genes up-regulated in NBTXR3 + RT showed an enrichment of cytokine activity (IL7, IFNA, IL16, IL11, IFNG), adaptive immunity (RAG1, GZMA, TAP1, TAP2, TBX21, STAT4, IFNG, LCK, LTK, CD37, CD22) and T cell receptor signaling pathway (CD28, CTLA4, CD274, BTLA, TIGIT, CD40LG, CD5, CD3E, ZAP70). Conclusions: NBTXR3 + RT induces a specific adaptive immune pattern. As such, it may contribute to convert “cold” tumor into “hot” tumor and be effectively combined with immunotherapeutic agents across oncology. These data warrant more tissue samples evaluation to reinforce these findings.