Pathological Responders Research Articles

Assessment of pathologic response in the colorectal cancer cohort of the IMHOTEP phase II trial of neoadjuvant pembrolizumab in dMMR/MSI tumors.

241 Background: Neoadjuvant treatment with immune check point inhibitors has shown promising results in localized deficient mismatch repair/microsatellite instability (dMMR/MSI) colorectal cancer (CRC), notably in terms of pathologic response. However, pathologic response has rarely been precisely assessed on both primary tumor and its corresponding lymph nodes (LN) as an end-point. We performed this analysis on the CRC samples selected from the IMHOTEP trial, a multicenter, single-arm study evaluating peri-operative Pembrolizumab in 4 different cohorts of patients with localized resectable dMMR/MSI tumors. Methods: We analyzed pathologic response on the 56 surgical specimens available from the CRC cohort. Pathologic response was assessed on primary tumor according to the percentage of Residual Viable Tumor (RVT) score, encompassing 4 groups : 0% = pathologic Complete Response (pCR) ; ≤10% = Major Pathologic Response (MPR) ; >10% < 50% = partial Pathologic Response (pPR) ; > 50% = lack of response (noPR). Pathologic response was assessed on lymph node (LN) according to 4 groups : negative LN without sign of sterilization (yN0 reg-), negative LN with sterilization (yN0 reg+) ; metastatic LN without tumor regression (yN+ reg-) ; metastatic LN with tumor regression (yN+ reg+).The type of regression, including colloid, fibrotic and necrotic features was reported, as well as the presence of tertiary lymphoid structures (TLS). pCR and MPR corresponded to pathologic responder patients and pPR and noPR to pathologic non responder patients. Results: In thisCRC cohort pCR, MPR, pPR and noPR were observed in n= 33 (58.9%), 7 (12.5%), 5 (8.9%) and 11 (19.6 %) cases and yN0 reg-, yN0 reg+, yN+ reg-, yN+ reg+ in 41 (73.2%) , 7 (12.5%), 7 (12.5%), and 1 (1.8 % ) cases. There was a significant association between pathologic responders (pCR + MPR) and negative LN status encompassing sterilized LN (p=0.04). Pathologic responders were more frequently associated with classical (Lieberkuhnian) adenocarcinoma than with other CRC special subtypes (mucinous, signet ring-cell, poorly cohesive subtypes)(p<0.01). Colloid response was the most frequent pattern of regression, observed in 42 (75%) cases, and predominant (>80% of pathologic response areas) in 14 (25%) cases. TLS were seen in 46 (82%) cases, without any significant association with the RVT score. However TLS were observed in all CRC cases with MPR. Conclusions: These preliminary results show pembrolizumab efficacy as a neoadjuvant monotherapy in terms of pathologic response on both primary CRC and corresponding LN, highlighting the need for a new and more accurate pathologic score. It also illustrates the potential impact of the histological subtypes. Complementary data will be available after updated pathologic reviewing of additional specimens from CRC patients and will also be correlated with outcome. Clinical trial information: NCT04795661 .

Outcomes of neoadjvuant chemotherapy versus chemoradiation for esophageal adenocarcinoma: A National Cancer Database analysis.

416 Background: While neoadjuvant chemoradiation (NCRT) has been the acceptable standard of care for esophageal adenocarcinoma (EAC), there has been a paradigm shift from recent trials have shown that neoadjuvant chemotherapy (NAC) is either equivalent or superior to NCRT. We sought to examine the outcomes of NAC versus NCRT in esophageal cancer from the National Cancer Database (NCDB). Methods: Utilizing the NCDB, we identified esophagectomy patients with EAC who underwent multiagent NCT versus multiagent NCRT. Overall Survival (OS) was analyzed with the Kaplan-Meier method and multivariate analysis (MVA) was performed to identify predictors of OS. Propensity score matching (PSM) was used to correct for baseline differences between groups. Results: After PSM, we identified 1007 patients in each group. Groups were equally balanced in age, gender, T/N stage, grade, and facility volume. There was improved lymphadenectomy and higher use of adjuvant therapy in NCT patients. There were significant improvements in R0 resection and pathologic response associated with NCRT patients. There was a significant improvement in OS in NCT versus NCRT. The median and 5-year OS was 42.7 months and 42% in NCT patients versus 34.2 months and 35% in NCRT patients (p = 0.001). For pathologic complete responders, median and 5-year OS was 101 months and 64% in NCT patients versus 71.2 months and 53% in NCRT patients (p = 0.04). On MVA, improved mortality was associated with female gender, pathologic N0, >10 nodes removed, pathologic partial or complete response, R0, well/moderate grade, NCT, adjuvant chemotherapy, and higher facility volume. There was also no survival benefit to adjuvant chemoradiation. Conclusions: Despite higher R0 and pathologic response associated with NCRT, NCT was superior to NCRT for OS in EAC patients. NCRT needs to be re-examined in its role as a treatment recommendation for operable EAC patients. Multivariate analysis for overall survival. Variable HR 95% CI P value Age 1.01 1.00 – 1.02 0.004 SexMaleFemale Reference0.79 0.64 – 0.98 0.03 Charlson Deyo score01 Reference1.05 0.91 – 1.21 0.54 Pathologic N-stageN0N+ Reference1.82 1.58 – 2.10 <0.001 LN removed<10>10 Reference0.81 0.68 – 0.97 0.02 ResponseNonePartialComplete Reference0.810.61 0.69 – 0.940.50 – 0.75 0.008<0.001 Margin statusR0R1 Reference1.24 1.01 – 1.52 0.04 GradeWell/moderatePoor Reference1.35 1.18 – 1.54 <0.001 Preop radiationYesNo Reference0.77 0.67 – 0.88 <0.001 Adjuvant therapyNoneChemotherapyChemoradiation Reference0.770.83 0.65 – 0.920.64 – 1.08 0.0040.17 Facility volumeLow (≤10/year)Medium (11-19/year)High (≥20/year) Reference0.860.78 0.72 – 1.030.67 – 0.90 0.10<0.001

Genomic profiling of matched tumor samples in patients with rectal cancer undergoing total neoadjuvant therapy.

213 Background: Total neoadjuvant therapy (TNT) is increasingly used for locally advanced rectal cancer. However, which patients benefit most from TNT remains to be elucidated. In this study we sequenced a TNT cohort with long-term follow-up to identify genomic correlates of TNT efficacy. Methods: Patients with locally advanced rectal cancer who underwent TNT followed by surgery (Oct 2016-June 2020) were identified at our institution. MSS patients with paired tissues (normal, biopsy, and surgery) with successful DNA extraction and sequencing were analyzed. Retrospective chart review collected patient demographics and clinical outcomes. Genomic analyses were performed with the R maftools package. Descriptive statistics were calculated with Fisher’s exact, Wilcoxon rank sum, and Wilcoxon rank sum exact tests. Univariate survival analyses (UVA) were calculated with Cox proportional hazards regressions. All statistical analyses were performed using R (v4.3.2). Results: 53 patients met inclusion criteria and 32 patients with paired tissues (64 samples) were obtained and successfully sequenced. All patients received chemotherapy, most commonly FOLFOX (81.3%) as part of TNT and a 5-FU based chemoradiation therapy (RT) regimen. Almost all patients received 50.4 Gy (93.8%). Median followup was 57 months (IQR: 47-68). There were 24 pathological responders (R) [complete/partial] and 8 nonresponders (NR) [stable disease/progression]. R vs NR were not statistically different across demographic or treatment characteristics. Local recurrences were infrequent (9.4% 3/32). No covariates were prognostic on UVA survival analyses. However, NR was associated with worse distant metastases free survival (DMFS) (HR = 4.11, CI 1.01-16.8, p = 0.048) on UVA. 5-year DMFS was 83% for R and 50% for NR, and the median DMFS was not reached for R, 41 mo for NR. Tumor mutation burden (TMB) did not change with treatment (pre = 4.5 vs post = 6.2 mutations/Mb; r, 1.7-10.3, p=0.59) and was not different on biopsy between R and NR (4.1 vs 5.9, p=0.09). Pre-treatment, the most mutated gene was APC (81%), [majority nonsense/frameshift (88%)], followed by TP53 (69%), [missense (59%)]. When comparing frequent mutations (n ≥ 5), PIEZO1 was more mutated in NR (63%, 5/8) than R (4% 1/24 patients) (p = 0.023 [multiple testing corrected]). Putative radioresistant KRAS-TP53 co-mutations were uncommon with similar representation in both groups (R 12.5%, 3/24, NR 12.5%, 1/8). Conclusions: Pathologic response positively correlated with DMFS in this cohort with long-term followup. PIEZO1 mutations were negatively prognostic for pathologic NR to TNT. This uncovers a potential new role in chemoRT resistance in addition to a previously reported association with metastatic spread. Further evaluation of PIEZO1 as a prognostic biomarker may help personalize appropriate treatment for patients with locally advanced rectal cancer.

Is pT0 a Reliable End Point for Biomarker Discovery for Preoperative Chemotherapy Response in Patients With Bladder Cancer?

Purpose: Traditional biomarker investigation schemas for chemotherapy response prediction in patients with bladder cancer relying on the pT0 status at radical surgery are confounded by the therapeutic effect of transurethral resection of bladder tumor (TURBT). Studying cN+ patients and assessing pN0 status presents a unique opportunity for overcoming this bias. Materials and Methods: We studied 26 patients with biopsy-proven cTanyN1-3M0 bladder cancer (2005-2016) who underwent induction chemotherapy and radical cystectomy with pelvic lymphadenectomy. Metastasis and overall survival (OS) outcomes were examined using Kaplan-Meier method and compared using log-rank test. Paired pretherapy primary bladder and nodal tissues were available for 10 patients. In these patients, whole-transcriptome RNA-seq analysis was performed on bladder tumor (for pT0 and pN0 prediction) and lymph-nodal metastasis (for pN0 prediction) tissues to identify differentially expressed genes (DEGs) with a false discovery rate < 0.1. Results: pN0 pathologic responders, but not pT0 responders, had significantly improved freedom from metastasis (5-year: pN0 88.9% vs pN+ 27.4%, log-rank P = .018) and OS (5-year: pN0 76.2% vs pN+ 12.2%, log-rank P = .024). Using RNA-seq data, we identified a significant discordance rate of 87.5% between DEG-based predictive signatures for pT0 and pN0 response to cisplatin-based chemotherapy. This datum, combined with the knowledge that ∼40% of patients who achieve pT0 status at radical surgery, achieve it simply through the therapeutic effect of TURBT (SWOG S8710), underscores a substantial bias in the current biomarker discovery initiatives that use pT0 as an end point. Conclusions: Our findings suggest a need for devising novel study designs to aid in the discovery of reliable biomarkers for preoperative chemo/immunotherapy response in bladder cancer. Clinical node-positive patients may be ideally situated but remain understudied.

Response-Adaptive Surgical Timing in neoadjuvant immunotherapy demonstrates enhanced pathologic treatment response in Head and Neck Squamous Cell Carcinoma.

We evaluated whether IDO-inhibitor BMS986205 (IDOi) + PD-1 inhibitor nivolumab enhanced T-cell activity and augmented immune-mediated antitumor responses in untreated, resectable HNSCC. We employed response-adaptive surgical timing to identify responders to immunotherapy and enhance their response. Patients with HNSCC were 3:1 randomized to receive nivolumab with or without BMS986205 PO daily (NCT03854032). In the combination arm, BMS986205 was initiated 7 days prior to nivolumab. Patients were stratified by HPV status. Response-adaptive surgical timing involved response assessment by radiographic criteria 4 weeks after nivolumab in both arms. Non-responders underwent surgical resection, while responders received 4 more weeks of randomized therapy before surgery. Biomarker analysis utilized pathologic treatment response (pTR) and RNA sequencing. Forty-two patients were enrolled, and the addition of IDOi to nivolumab did not result in greater rate of radiographic response (p=0.909). Treatment was well-tolerated with only 2 (5%) patients experiencing grade 3 immune-related adverse events. The addition of IDO-inhibitor augmented rates of pTR in patients with high baseline IDO RNA expression (p<0.05). Response-adaptive surgical timing demonstrated reliability in differentiating pathologic responders versus non-responders (p=0.009). A pretreatment NK cell signature, PD-L1 status, and IFN-g expression in the HPV- cohort correlated with response. HPV+ cohort found B-cell and CAF signatures predictive of response/non-response. Response-adaptive surgical timing enhanced treatment response. IDO-inhibitor BMS986205 augmented pTR in patients with high IDO1-expression in baseline samples, indicating a need for identifying and targeting resistant nodes to immunotherapy. HPV-status-dependent signatures predicting response to immunotherapy in HNSCC warrant further study.

Computed Tomography-Based Radiomics with Machine Learning Outperforms Radiologist Assessment in Estimating Colorectal Liver Metastases Pathologic Response After Chemotherapy.

This study was designed to assess computed tomography (CT)-based radiomics of colorectal liver metastases (CRLM), extracted from posttreatment scans in estimating pathologic treatment response to neoadjuvant therapy, and to compare treatment response estimates between CT-based radiomics and radiological response assessment by using RECIST 1.1 and CT morphologic criteria. Patients who underwent resection for CRLM from January 2003-December 2012 at a single institution were included. Patients who did not receive preoperative systemic chemotherapy, or without adequate imaging, were excluded. Imaging characteristics were evaluated based on RECIST 1.1 and CT morphologic criteria. A machine-learning model was designed with radiomic features extracted from manually segmented posttreatment CT tumoral and peritumoral regions to identify pathologic responders (≥ 50% response) versus nonresponders. Statistical analysis was performed at the tumor level. Eighty-five patients (median age, 62 years; 55 women) with 95 tumors were included. None of the subjectively evaluated imaging characteristics were associated with pathologic response (p > 0.05). Inter-reader agreement was substantial for RECIST categorical response assessment (K = 0.70) and moderate for CT morphological group response (K = 0.50). In the validation cohort, the machine learning model built with radiomic features obtained an area under the curve (AUC) of 0.87 and outperformed subjective RECIST assessment (AUC = 0.53, p = 0.01) and morphologic assessment (AUC = 0.56, p = 0.02). Radiologist assessment of oligometastatic CRLM after neoadjuvant therapy using RECIST 1.1 and CT morphologic criteria was not associated with pathologic response. In contrast, a machine-learning model based on radiomic features extracted from tumoral and peritumoral regions had high diagnostic performance in assessing responders versus nonresponders.

Spatial multi-omics reveal intratumoral humoral immunity niches associated with tertiary lymphoid structures in pancreatic cancer immunotherapy pathologic responders.

Integrated multi-modal spatial profiling of human PDAC tumors from neoadjuvant immunotherapy clinical trials reveal diverse spatial niches enriched in TLS.TLS maturity is influenced by tumor location and the cellular neighborhoods in which TLS immune cells are recruited.Unsupervised machine learning of genome-wide signatures on spatial transcriptomics data characterizes the TLS-enriched TME and associates TLS transcriptomes with survival outcomes in PDAC.Interactions of spatially variable gene expression patterns showed TLS maturation is coupled with immunoglobulin distribution and ECM remodeling in pathologic responders.Intratumoral plasma cell and immunoglobin gene expression spatial dynamics demonstrate trafficking of TLS-driven humoral immunity in the PDAC TME. We report a spatial multi-omics atlas of PDAC tumors from a series of immunotherapy neoadjuvant clinical trials. Intratumorally, pathologic responders exhibit mature TLS that propagate plasma cells into malignant niches. Our findings offer insights on the role of TLS-associated humoral immunity and stromal remodeling during immunotherapy treatment.

Safety and Efficacy of Conversion Therapy After Systemic Chemotherapy in Advanced Esophageal Cancer with Distant Metastases: A Multicenter Retrospective Observational Study.

Patients with esophageal squamous cell carcinoma (ESCC) with distant metastasis were treated with systemic chemotherapy. Recent advances in multimodal treatments have made conversion therapy a viable option for patients with incurable ESCC. We aimed to assess the safety and efficacy of conversion therapy for ESCC with distant metastases. Conversion therapy was defined as surgery or chemoradiotherapy (CRT) used to cure tumors that were previously considered incurable because of distant metastasis. We conducted a retrospective review of patients who underwent ESCC conversion therapy and assessed the treatment outcomes, including adverse events and survival rates. A total of 147 patients from 22 institutions were included. Systemic chemotherapy was initially administered to all patients. The most common M1 factor was the para-aortic lymph node, accounting for 55% of cases. Following the initial treatment, 116 patients underwent surgery, with 31 receiving CRT as conversion therapy. Postoperative complications in surgery patients included pneumonia (16%), anastomotic leakage (7%), and recurrent laryngeal nerve palsy (6%). During CRT, 18% of patients developed grade 3 or higher non-hematological toxicities. The 5-year overall survival (OS) rate was 31.7%. Pathological responders had significantly longer OS than non-responders (hazard ratio 0.493, p=0.012). The distribution of distant metastasis, regimen type, clinical response, and conversion therapy modality did not have a significant impact on OS. Conversion therapy can be safely performed for ESCC with distant metastasis and has a favorable prognosis.

Normative Values for the Children Voice Handicap Index-10 (CVHI-10) and for the Children Voice Handicap Index-10 for Parents (CVHI-10-P)

ObjectivesThe objective of this study was to establish normative data and cut-off scores for the Children Voice Handicap Index-10 (CVHI-10) and the Children Voice Handicap Index-10 for Parents (CVHI-10-P) MethodsFor normative data, CVHI-10 and CVHI-10-P questionnaires originally developed in the Italian language were completed by 201 children without dysphonia and with no history of voice disorders, and by one of their parents. The results were analyzed for mean, standard deviation (SD), and standard error of the mean (SEM) for both questionnaires. For cutoff values determination, data from 49 dysphonic children and from one of their parents were also used. This analysis was based on the sensitivity and specificity indicators of the questionnaires using the ‘‘receiver operating characteristic’’ (ROC) curve. ResultsAnalysis of the questionnaires related to healthy children revealed a mean of 0.26 (SD 0.74; SEM 0.06) for CVHI-10 and a mean of 0.15 (SD 0.49; SEM 0.04) for CVHI-10-P for the normative values. ROC curve analysis allowed us to establish the cutoff scores of 2.5 for CVHI-10 and 1.5 for CVHI-10-P. ConclusionsThis study offers normative data for CVHI-10 and CVHI-10-P and provides cutoff values for both questionnaires to distinguish healthy and pathologic responders.

Pathologic Response and Survival after Neoadjuvant Chemotherapy with Bevacizumab Followed by Surgery for Clinical Stage II/IIIA Nonsquamous Non-Small-Cell Lung Cancer: Results from a Phase II Feasibility Study (NAVAL).

The objective of this study was to evaluate the relationship between pathologic response and survival in patients with clinical stage II/IIIA nonsquamous non-small-cell lung cancer (NSCLC) who intended to undergo neoadjuvant chemotherapy with bevacizumab, followed by surgery. In this phase II NAVAL study evaluating the feasibility of neoadjuvant chemotherapy with cisplatin (75 mg/m2), pemetrexed (500 mg/m2), and bevacizumab (15 mg/kg), followed by surgery, progression-free survival (PFS) and overall survival (OS) were assessed as the secondary endpoints. Patients were categorized based on the proportion of residual viable primary tumor in the resected specimen after neoadjuvant chemotherapy: those with residual tumor in less than one-third were classified as pathologic responders, the rest as nonresponders. Of the 30 patients, 25 underwent surgical resection after three cycles of neoadjuvant chemotherapy with bevacizumab; 5 did not undergo surgery. Among all 30 patients, the rates of 2- and 5-year PFS were 41.5% and 34.6%, respectively, and the rates of 2- and 5-year OS were 70.0% and 60.0%, respectively. A total of 6 patients (20%) were classified as pathologic responders; the other 24 (80%), as nonresponders. The five-year PFS differed significantly between pathologic responders (100%) and nonresponders (17.5%; p = 0.002). The five-year OS also differed significantly between pathologic responders (100%) and nonresponders (43.5%; p = 0.006). Pathologic response seems to be a predictor of survival. Long-term survival after surgery is expected for pathologic responders, whereas additional therapy is needed for nonresponders.

FDG-PET associations with pathological response and survival with neoadjuvant immunotherapy for melanoma.

9523 Background: This study sought to describe the changes seen with FDG-PET following neoadjuvant immunotherapy in melanoma patients (pts), and explore associations with pathological response and recurrence-free survival (RFS). Methods: Two prospective clinical trial cohorts of stage III pts with RECIST measurable nodal melanoma were included; 1) NeoTrio, 13 pts received 2 doses of preoperative pembrolizumab alone, and 2) NeoPele, 20 pts received 2 doses of pembrolizumab and 5 weeks of lenvatinib preoperatively. All pts underwent baseline and week 6 (preoperative) FDG-PET assessments and all had surgery. PET responses were evaluated based on the modified EORTC criteria. In addition to the standard categories Complete Metabolic Response (CMR), Partial Metabolic Response (PMR), Stable Metabolic Disease (SMD), and Progressive Metabolic Disease (PMD), a novel category was established, near-CMR, where the maximum standardized uptake value (SUVmax) decreased by more than 90%. PET responses were determined while blinded to the outcome data. Pathological response was determined as per INMC criteria. Results: 33 pts were included, 67% male, median age 65 years, 48% BRAF mutant. Pathological response, PET response and correlations are shown in the Table. All 8 (24%) pts achieving CMR or near-CMR obtained major pathologic response (MPR), while the 14 pts (42%) with PMR had variable pathological outcomes (57% MPR, 21% pPR, 21% pNR). For the 6 pts with PMD, 5 (83%) had pNR and the one pts who achieved pCR recurred with brain metastases. After a median 29.9 mo follow-up (95% CI 27.0-33.1), PET response associated with RFS; those with CMR/near CMR had 100% 24mo RFS (nil recurrences to date) while those with PMR or SMD had inferior survival (79% and 80% 24mo RFS), and those with PMD the worst outcomes (17% 24mo RFS, all pts except one have recurred) (p=0.0029). The predictive value of PET and pathology for RFS was assessed using the Cox Proportional Hazards model. 12- and 24-month RFS AUCs of PET and pathology response were similar at 81.5% (95% CI: 67.7-95.3) vs. 80.9% (95% CI: 67.8-93.9), and 83.3% (95% CI: 69.1-97.5%) vs. 80.8% (95% CI: 66.6-94.9), respectively. Conclusions: FDG-PET demonstrates utility in predicting pathological response and survival with neoadjuvant immunotherapy in melanoma. PET may identify pts who are not going to be pathological responders and who have the worst survival outcomes, enabling a potential switch of neoadjuvant systemic therapy. [Table: see text]

Biomarker analysis and updated clinical outcomes: Neoadjuvant systemic treatment (NST) with nivolumab (nivo) and relatlimab (rela) in surgically resectable melanoma.

9587 Background: NST with immune checkpoint blockade (ICB) improves clinical outcomes over upfront surgery followed by adjuvant treatment (tx) in patients (pts) with stage III, surgically resectable melanoma. The NST platform also provides an opportunity for deep translational analysis to identify baseline (BL) biomarkers predicting pathologic response and to gain insights into resistance. BL biomarkers, including gene expression signatures (GES) such as IFN-γ/ tumor mutational burden, tumor infiltrating lymphocytes, and presence of tertiary lymphoid structures, have been associated with pathologic response to NST with anti-PD1 and/or anti-CTLA4 antibodies. These studies have not evaluated the newest ICB combination, nivo (anti-PD1) + rela (anti-LAG3), which achieved a major pathologic response rate (MPR) (≤10% viable tumor) of 63% in a Ph II study (NCT02519322). Here we report GES analysis from BL and longitudinal tumor tissues obtained on this study and correlations with outcomes. Methods: Longitudinal tissue was collected from 30 pts treated on the clinical trial and available RNA analyzed using the NanoString nCounter PanCancer IO360 panel. Clinical outcomes, including recurrence and event-free survival, were also updated with longer follow-up. Pts were grouped into MPR and non- major pathologic responders (non MPR). Normalization, differential expression / GES evaluation was performed using nSolver Advanced Analysis software. Differential expression is fit on a per signatures basis using a linear model for analysis. P-values were adjusted within each analysis and on the grouping variable level difference t-test using the Benjamini and Yekutieli False Discovery Rate adjustment to account for correlations amongst the tests. BL analysis was grouped based on pathologic response, MPR vs non-MPR. Results: Of the 30 pts (median follow up 44 months), 53 RNA samples from 26 patients (9 NR and 17 R) were included in the full analysis. Immune GES with significantly higher (adjusted p&lt; 0.05) differences at BL in MPR vs non-MPR included: B cells, CD45, CD-8+ T cells, TIGIT, IDO1, and IFN-γ. Significantly higher B7-H3 GES at BL was associated with non MPR. Additional analyses (i.e., cell population changes over time) and association with event outcomes are underway. Conclusions: To our knowledge, this is the first longitudinal RNA analysis reported from pts treated with nivo+rela. BL immune features associated with major pathologic response include higher GES of B cells, CD45+ cells, CD8 T cells, and increased expression of TIGIT, IDO and IFN-y. Additionally, higher B7-H3 in non MPR pts may indicate a clinically actionable strategy for further evaluation. Ongoing analyses of longitudinal samples and correlations with clinical outcomes are underway and will be presented. Clinical trial information: NCT02519322 .

Antigen-specific profiling for neoadjuvant anti-PD-1 therapy in melanoma.

9576 Background: Anti-PD-1 therapy (aPD-1) has had significant clinical success in extending survivability of melanoma patients. However, two-third of the patients do not achieve long-lasting benefits, and currently, there exists no reliable method for predicting clinical response. We test whether monitoring melanoma-specific CD8 T cells in blood, lymph node, and tumor enables us to gain insights into the mechanism of clinical resistance, and identify potential predictive biomarkers. Methods: We leveraged a phase 2 clinical trial of neoadjuvant PD-1 blockade at University of Pennsylvania where patients with stage III melanoma patients receive a pre-treatment biopsy, treatment with a single dose of the aPD-1 therapy, followed by tumor and lymph node resection 4 weeks later, allowing for access to paired blood and tumor samples. We used a combinatorial tetramer system to track panels of 10 HLA-restricted melanoma and viral-specific CD8 T cell populations simultaneously. Results: Out of 35 patients analyzed, 53% of patients had detectable melanoma-specific CD8 T cells. Notably, these cells exhibited exhausted phenotypes both in blood and tumor, whereas viral-specific T cells displayed features resembling effector and memory CD8 T cells in blood and tumor, respectively. Thus. the presence of tumor antigen emerges as a crucial determinant in shaping the phenotype of melanoma-specific CD8 T cells, above that of the tissue microenvironment. Analysis of resected lymph node samples following PD-1 blockade reveals their supportive role in activating and proliferating anti-tumor T cells. Finally, pathologic responders to PD-1 blockade are characterized by both a higher quantity and a less exhausted phenotype of tumor-specific CD8 T cells. This suggests that assessing both the quantity and quality of these T cells can serve as a predictive indicator to distinguish responders from non-responders. Conclusions: These findings highlight the feasibility of antigen-specific profiling in a clinical trial setting, the importance of melanoma-specific CD8 T cells in checkpoint blockade responses, and their potential use an early on-treatment biomarker of clinical outcomes.

Abstract 1159: Machine learning integrating spatial omics uncovers humoral immunity patterns in intratumoral tertiary lymphoid structures in pancreatic cancer pathologic responders

Abstract Background: In pancreatic ductal adenocarcinoma (PDAC), rare long-term survivors correlate with high intratumoral tertiary lymphoid structure (TLS) density. This finding prompted our investigation of clinically viable strategies to induce TLS in patients with immune-excluded tumors. We previously reported the induction of intratumoral TLS following administration of a neoadjuvant GM-CSF-secreting allogeneic vaccine (GVAX) to PDAC patients (NCT00727441). However, no clinical benefit was observed, likely owing to immune tolerance mechanisms governing the PDAC tumor microenvironment (TME). We previously observed upregulation of both the PD-1 and 4-1BB pathways with GVAX, and thus in a subsequent neoadjuvant trial combined GVAX with PD-1 blockade and 4-1BB agonism (NCT02451982) which was associated with pathologic responses. We hypothesized this combination strategy induced TLS of higher maturity and anti-tumor activity compared to GVAX alone. Methods: To explore how this therapeutic strategy affected TLS morphology and intercellular crosstalk, we leveraged the Visium spatial transcriptomics platform and a 35-marker customized TLS panel for imaging mass cytometry. We generated cellular and molecular maps of the TME after neoadjuvant treatment in 26 PDAC patients (GVAX n=19, GVAX+aPD1 n=2, GVAX+aPD1+a41BB n=5). To compare TLS maturation in parallel with secondary lymphoid organ-mediated tumor immunity, we also profiled tumor-adjacent lymph nodes. We applied unsupervised learning with non-negative matrix factorization (NMF) and trained AI-enabled image classification models to characterize cellular states within tissue structures of interest. Results: We identified spatial gene expression NMF patterns in PDAC TLS spanning across distinct morphologies and neoadjuvant treatment arms. Intratumoral TLS after GVAX were found to propagate activated B cells expressing immunoglobulins that infiltrated into malignant cellular niches. TLS NMF patterns were also associated with autoimmune disease signatures, such as diabetes, in a subset of patients. We scored TLS using tumor-draining lymph nodes as a reference and found increased maturation of TLS after PD-1 blockade, while addition of 4-1BB agonism significantly boosted the cytotoxic NK/T cell compartment compared to GVAX alone. Conclusions: We present machine learning approaches for spatial multi-omics analysis to characterize the TLS-enriched TME. We mined genome-wide spatial TLS gene expression patterns elucidating the spatial dynamics of humoral immunity of rare immunotherapy pathologic responders in PDAC. Altogether our findings shed light on the plasticity of TLS in neoadjuvant immunotherapy and suggest future immunotherapy approaches should target both humoral and cytotoxic NK/T cell compartments to augment responses in solid tumors. Citation Format: Dimitrios N. Sidiropoulos, Sarah M. Shin, Alexander Girgis, Daniel H. Shu, Janelle Montagne, Atul Deshpande, Jeanette A. Johnson, Lucie Dequiedt, Victoria Jacobs, Aleksandra Ogurtsova, Guanglan Mo, Xuan Yuan, Genevieve Stein-O’Brien, Mark Yarchoan, Qingfeng Zhu, Ashley Kiemen, Elizabeth M. Jaffee, Lei Zheng, Won Jin Ho, Robert Anders, Elana J. Fertig, Luciane T. Kagohara. Machine learning integrating spatial omics uncovers humoral immunity patterns in intratumoral tertiary lymphoid structures in pancreatic cancer pathologic responders [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1159.

Evaluation of the neoadjuvant chemotherapy response in osteosarcoma using the MRI DWI-based machine learning radiomics nomogram.

To evaluate the value of a nomogram combined MRI Diffusion Weighted Imaging (DWI) and clinical features to predict the treatment response of Neoadjuvant Chemotherapy (NAC) in patients with osteosarcoma. A retrospective analysis was conducted on 209 osteosarcoma patients admitted into two bone cancer treatment centers (133 males, 76females; mean age 16.31 ± 11.42 years) from January 2016 to January 2022. Patients were classified as pathological good responders (pGRs) if postoperative histopathological examination revealed ≥90% tumor necrosis, and non-pGRs if <90%. Their clinical features were subjected to univariate and multivariate analysis, and features with statistically significance were utilized to construct a clinical signature using machine learning algorithms. Apparent diffusion coefficient (ADC) values pre-NAC (ADC 0) and post two chemotherapy cycles (ADC 1) were recorded. Regions of interest (ROIs) were delineated from pre-treatment DWI images (b=1000 s/mm²) for radiomic features extraction. Variance thresholding, SelectKBest, and LASSO regression were used to select features with strong relevance, and three machine learning models (Logistic Regression, RandomForest and XGBoost) were used to construct radiomics signatures for predicting treatment response. Finally, the clinical and radiomics signatures were integrated to establish a comprehensive nomogram model. Predictive performance was assessed using ROC curve analysis, with model clinical utility appraised through AUC and decision curve analysis (DCA). Of the 209patients, 51 (24.4%) were pGRs, while 158 (75.6%) were non-pGRs. No significant ADC1 difference was observed between groups (P>0.05), but pGRs had a higher ADC 0 (P<0.01). ROC analysis indicated an AUC of 0.681 (95% CI: 0.482-0.862) for ADC 0 at the threshold of ≥1.37×10-3 mm²/s, achieving 74.7% sensitivity and 75.7% specificity. The clinical and radiomics models reached AUCs of 0.669 (95% CI: 0.401-0.826) and 0.768 (95% CI: 0.681-0.922) respectively in the test set. The combined nomogram displayed superior discrimination with an AUC of 0.848 (95% CI: 0.668-0.951) and 75.8% accuracy. The DCA suggested the clinical utility of the nomogram. The nomogram based on combined radiomics and clinical features outperformed standalone clinical or radiomics model, offering enhanced accuracy in evaluating NAC response in osteosarcoma. It held significant promise for clinical applications.

An online rectal cancer tumoroid biorepository: A resource to facilitate multimodal data integration.

159 Background: Advancing genetic and computational technologies have increased the complexity and quantity of data available in the field of rectal cancer research. As such, there is a need for a centralized source of data to aid and organize current research efforts. To this end, our team has created a unique online biorepository of rectal cancer tumoroids which may serve as a resource for a community of researchers. Methods: The rectal cancer tumoroid biorepository was created in cBioPortal in 2015. Organoids were derived from patient tumor samples (tumoroids). These samples represented multiple treatment timepoints and included primary, recurrent, and metastatic tumors. These tumoroids were further analyzed by various assays such as MSK-IMPACT and IC50 (to fluorouracil, FOLFOX, and FOLFIRI) to obtain patient-specific genomic and chemosensitivity data. A tumoroid profile was then created in cBioPortal for each sample. Clinical information was collected by chart review and annotated into the tumoroid profiles using the unique features of cBioPortal. These included interactive filters and graphical depictions of patient demographics, clinical and pathologic staging, treatment course, clinical response, overall survival, and disease-free survival. Results were organized in an intuitive visual display for convenient analysis. Novel features such as chemosensitivity plots and an interactive patient timeline were incorporated as well. Results: In total, 401 rectal cancer tumoroids have been derived from 177 unique patients. Approximately 32% of the tumoroids were from patients 50 years or younger, and 63% of patients have a treatment naïve sample in our repository. Ten percent of tumoroids were derived from T1-T2 tumors, 56% from T3 tumors, and 17% from T4 tumors. Additionally, 14% of tumoroids were derived from primary tumor recurrences while 6% were derived from metastases. Of the 78% of tumoroids with completely annotated clinical data, 8% were MSI-H, 11% were clinical complete responders, and 5.5% were pathologic complete responders. Lastly, complete IC50 data with clinical correlates has been established for 20% of tumoroids. These data show that tumoroids with a high sensitivity to chemotherapy (FOLFOX) correlated with a 3.3-fold increase in clinical complete response rates in the corresponding patients (p=0.0263). Conclusions: Integrating histopathological, clinicogenomic, and tumoroid response data, this expanding online resource provides a platform to identify valid biomarkers for patient treatment response. This publicly available biorepository built within cBioPortal is intuitive and flexible to accommodate and organize a wide range of data and has the potential to serve as an important resource in rectal cancer research.

The efficacy and safety of conversion therapy after initial systemic chemotherapy in advanced esophageal cancer with distant metastases: A multicenter retrospective observational study.

310 Background: Systemic chemotherapy, with or without radiation, has been the standard treatment for esophageal squamous cell carcinoma (ESCC) with distant metastasis. The increased efficacy of multimodality treatment allows for the consideration of conversion therapy with curative intent for initially unresectable ESCC after initial treatment. In the present study, we examined the safety and effectiveness of conversion therapy for ESCC. Methods: Conversion therapy was defined as surgery or chemoradiation therapy (CRT) aiming at cure after initial treatment for tumors that were initially unresectable due to distant metastasis. The patients who underwent conversion therapy for ESCC between 2011 and 2021 at participating institutions were retrospectively reviewed. Patient backgrounds, treatment outcomes, and overall survival (OS) were evaluated. Results: From 22 institutions, 149 patients were enrolled. As defined, all patients received systemic chemotherapy as an initial treatment. The distant metastatic sites in para-aortic lymph nodes/extra regional mediastinal lymph nodes/lung/liver/bone/others were 81(54%)/19 (13%)/14 (9%)/11 (7%)/4 (3%)/20 (14%), respectively. After the initial treatment, 116 patients underwent surgery and 33 patients received CRT as conversion therapy. Of 116 patients who underwent conversion surgery, the incidence rate of postoperative pneumonia/leakage/recurrent laryngeal nerve palsy was 16%/7%/6%, respectively. R0 resection was obtained in 87%. Regarding the non-hematological toxicities during conversion CRT (CTCAE grade 3 or higher), decreased appetite/dysphagia/esophagitis was 21%/15%/9%, respectively. No grade 4 or higher hematologic toxicities were observed. The 3-year OS (3y-OS) rate for all patients was 41.9%; no significant differences were found between surgery and CRT groups (43.3% vs 37.0%, p = 0.112). Pathological responders showed a significantly longer OS than non-responders (3y-OS, 56.4% vs 36.1%, p = 0.010). The distribution or number of distant metastases were not identified as prognostic factors. Conclusions: This study showed that conversion therapy for ESCC patients with distant metastasis could be conducted safely and have a favorable prognosis. Since its survival benefit would depend on the pathological response, it is important to develop an indicator to predict pathological response before surgery and carefully select appropriate candidates of conversion therapy in ESCC.

Value of 68Ga-FAPI-04 and 18F-FDG PET/CT in Early Prediction of Pathologic Response to Neoadjuvant Chemotherapy in Locally Advanced Gastric Cancer.

This prospective study investigated whether PET parameters from 18F-FDG and 68Ga-fibroblast activation protein inhibitor (FAPI)-04 PET/CT can predict a pathologic response to neoadjuvant chemotherapy (NAC) early in patients with locally advanced gastric cancer (LAGC). Methods: The study included 28 patients with LAGC who underwent 18F-FDG PET/CT and 68Ga-FAPI-04 PET/CT at baseline and after 1 cycle of NAC. PET parameters including SUV and tumor-to-background ratio (TBR), as well as the change rate of SUV and TBR, were recorded. Patients were classified as major or minor pathologic responders according to postoperative pathology findings. We compared the PET parameters between the 2 pathologic response groups and different treatment regimens and analyzed their predictive performance for tumor pathologic response. Results: Major pathologic responders had significantly lower 68Ga-FAPI change rates (percentage SUVmax [%SUVmax], percentage SUVpeak [%SUVpeak], and percentage TBR [%TBR]) than minor pathologic responders. Among the PET parameters, 68Ga-FAPI %SUVmax (area under the curve, 0.856; P = 0.009), %SUVpeak (area under the curve, 0.811; P = 0.022), and %TBR (area under the curve, 0.864; P = 0.007) were significant parameters for early prediction of pathologic response to NAC in LAGC; they had the same predictive accuracy of 89.29%, with the thresholds of decrease to at least 52.43%, 60.46%, and 52.96%, respectively. In addition, 68Ga-FAPI %SUVmax and %TBR showed significant differences between the different treatment regimens. Conclusion: In this preliminary study, 68Ga-FAPI-04 PET change rate parameters were preferable to 18F-FDG in predicting pathologic response to NAC at an early stage in LAGC. 68Ga-FAPI %SUVmax and %TBR may be better predictors of therapeutic response between different treatment regimens. These findings may help optimize the treatment for patients with LAGC.

Comparison of responses to neoadjuvant and adjuvant chemotherapies in muscle-invasive bladder cancer

BackgroundBladder cancer surgery is critical for treatment, and systemic treatment before or after cystectomy may be necessary. We aimed to investigate the efficacy and response to neoadjuvant and adjuvant treatments.MethodsData on 93 patients with resectable muscle-invasive bladder cancer were analyzed retrospectively. Patients who received neoadjuvant and adjuvant chemotherapies were included. The neoadjuvant treatment group was divided into pathological responders and non-responders. Overall survival and disease-free survival were calculated.ResultsThe median age was 61.5 years; there were 6 female and 87 male patients. Baseline characteristics were similar between the groups. While there was no difference in OS between the neoadjuvant and adjuvant treatment groups (20 months vs. not reached), DFS was significantly higher in the adjuvant group (20.6 vs. 25.3 months). While there was no significant difference in DFS between the responders and non-responders to neoadjuvant treatment (20.6 vs. 19.1 months), OS was significantly longer in the responders (Not reached vs. 12.3 months).ConclusionsOur results concluded that neoadjuvant and adjuvant chemotherapies have similar survival rates, but no response was associated with poor outcomes. Determining the group for patient selection may be helpful for optimal management.

Phase II clinical trial of neoadjuvant anti-PD-1 (toripalimab) combined with axitinib in resectable mucosal melanoma

The outcome of patients with resectable mucosal melanoma is poor. Toripalimab combined with axitinib has shown impressive results in metastatic mucosal melanoma with an objective response rate of 48.3% and a median progression-free survival of 7.5 months in a phase Ib trial. It was hypothesized that this combination administered in the neoadjuvant setting might induce a pathologic response in resectable mucosal melanoma, so we conducted this trial. This single-arm phase II trial enrolled patients with resectable mucosal melanoma. Patients received toripalimab 3 mg/kg once every 2 weeks (Q2W) plus axitinib 5 mg two times a day (b.i.d.) for 8 weeks as neoadjuvant therapy, then surgery and adjuvant toripalimab 3 mg/kg Q2W starting 2 ± 1weeks after surgery for 44 weeks. The primary endpoint was the pathologic response rate according to the International Neoadjuvant Melanoma Consortium recommendations. Between August 2019 and October 2021, 29 patients were enrolled and received treatment, of whom 24 underwent resection. The median follow-up time was 34.2 months (95% confidence interval 20.4-48.0 months). The pathologic response rate was 33.3% (8/24; 4 pathological complete responses and 4 pathological partial responses). The median event-free survival for all patients was 11.1 months (95% confidence interval 5.3-16.9 months). The median overall survival was not reached. Neoadjuvant therapy was tolerable with 8 (27.5%) grade 3-4 treatment-related adverse events and no treatment-related deaths. Tissue samples of 17 patients at baseline and after surgery were collected (5 responders and 12 nonresponders). Multiplex immunohistochemistry demonstrated a significant increase in CD3+ (P= 0.0032) and CD3+CD8+ (P= 0.0038) tumor-infiltrating lymphocytes after neoadjuvant therapy, particularly in pathological responders. Neoadjuvant toripalimab combined with axitinib in resectable mucosal melanoma demonstrated a promising pathologic response rate with significantly increased infiltrating CD3+ and CD3+CD8+ T cells after therapy.