Villasboas, José C.

e18807 Background: CUP represents both a diagnostic and a management challenge. Despite improvements through sophisticated imaging modalities, specific and sensitive testing using immunohistochemistry, a concrete determination of the site of origin of the primary tumor can still be a diagnostic challenge Hereby, we described the genomic landscape of patients with CUP treated at our institution. Methods: Retrospective study of patients with CUP treated at Mayo Clinic Rochester MN from 2010 to 2021. Next generation sequencing (NGS) information was abstracted, and alterations were ranked into different levels of actionability following the Onco KB framework. All data were analyzed by the SPSS version 22.0 software (SPSS, Chicago, IL, United States). Results: From a total of 214 patients, we identified 67 (32%) patients in whom NGS was performed. Among patients with available NGS the median age was 64 years (range: 35-86) and 51% were female. the most prevalent histology included adenocarcinoma (39%), carcinoma NOS (31%), and neuroendocrine tumors (12%). NGS on tumor (t-NGS) was available in 56 (84 %) patients, circulating tumor NGS (b-NGS) was available in 12 (18%) patients, and only 1 patient had both testing available. Among the 56 patients with available t-NGS, MSI-high was detected in 9 patients, whereas among the 12 patients with available b-NGS, MSI-high was detected in 8 patients; yielding an MSI-high detection rate of 16% and 67% for t-NGS and b-NGS. In this cohort, there were a total of 474 genomic alterations detected from which 103 (22 %) were able to be ranked into one therapeutic level following the OncoKB framework. Genomic alterations were most observed among patients with carcinoma (n = 50, 48.53%) adenocarcinoma (n = 33, 32.03 %), squamous cell carcinoma (n = 3, 2.91 %) and neuroendocrine tumor (n = 2, 1.94%). Following the OncoKB framework, 39-level 1 genomic alterations were detected in a total of 14 genes. The most common level 1 genomic alterations comprised the BRCA2 (20.51%), NF1 ATM (17.95%) and HER2/NEU (ERBB2) (15.38%) genes. Therapeutic level 2 included 51 genomic alterations in 13 genes of which KRAS (17.65%), BRAF (15.69%), and BRCA2 (15.69%) were the most prevalent mutated genes. Additionally, level R comprised 13 genomic alterations in the following genes: KRAS (69.23) NRAS (23.08%) and PDGFRA (7.69%). Conclusions: CUP are malignancies rich in potentially actionable alterations, and NGS of tissue and blood samples can inform systemic therapy decisions. Alteration-specific targeted therapy may be an option for a substantial proportion of patients. NGS of tumor tissue or blood should be considered for all patients with CUP.

e18803 Background: CUPs are a heterogeneous group of metastatic cancers for which a standardized diagnostic work-up fails to identify the site of origin at the time of diagnosis. CUP accounts for 3%-5% of all cancer diagnoses worldwide, and the natural history of patient with CUP differs from that of patients (pts) with cancer with known primary tumor. Here we report and summarize the clinical features of patients with CUP treated at Mayo Clinic. Methods: Retrospective study of patients treated at Mayo Clinic Rochester MN from 2010 to 2021. Patient demographics, tumor-related variables, treatment-related variables, and clinical data were extracted. Descriptive statistics were used, and all data were analyzed by the SPSS version 22.0 software (SPSS, Chicago, IL, United States). Results: From a total of 214 pts, 207 pts were included, as primary tumor site was identified in 7 patients after initial evaluation. The pts in this study were predominantly white (87%) of female (50.2%) gender with a mean age of 63 (SD: 13) without history of smoking (51%) and either private or public insurance (82.6%). The predominant histology was adenocarcinoma (30%), followed by neuroendocrine neoplasms (27%), and carcinoma NOS (not otherwise specified) (25%). The most prevalent grade in this cohort was grade III with poorly differentiated tumor cells. All pts had diagnostic imaging and the most used imaging modalities included CT (81.2%), and PET-CT (43.5%). In our cohort, the 3 most common sites of metastases included lymph nodes (57.5%), liver (37.8%), lung (34.3%), and bone (23.7%); and in 64% of pts, there was a specific presentation pattern including liver-predominant (24.6%), lymph node-predominant (24.6%), bone-predominant (7.7%), and peritoneal carcinomatosis (7.7%). The majority of pts received systemic therapy (69%) as first line of therapy and the most frequent first line regimens included platinum-doublet (26.5%), gemcitabine-based regimen (20.7%), 5FU-based regimens (18%) and somatostatin analogs (16.7%); whereas salvage radiation and ablation were offered to 11% of pts and surgery to 17%. The median follow-up time was 22 months (IQR: 45) with a median survival time of 23 months and the 3-year cumulative survival rate was 30%. Conclusions: The heterogenous nature of CUPs and lack of specific immunohistochemical signature prevents primary tissue of origin diagnoses in CUP pts. Without the identification of a primary origin site, treatment is restricted to generic chemotherapy with limited benefit as demonstrated in this cohort.

e18802 Background: CUP is a rare cancer with an incidence of 7–12 cases per 100,000/year. CUP is defined as metastatic cancer with no identifiable primary tumor despite comprehensive evaluation. Despite its heterogeneous clinicopathological presentation, the treatment of CUP has primarily been with platinum-based combination chemotherapies but results are poor and survival is short. Here, we describe survival outcomes in real-world dataset of patients with CUP seen at a tertiary referral center. Methods: Retrospective study of patients treated at Mayo Clinic, Rochester MN, from 2010 to 2021. Survival probabilities were estimated with the Kaplan-Meier method. We used Cox proportional hazard regression with forward modeling to explore the association between each variable and death. Overall survival (OS) analysis was conducted in the entire cohort, and it was stratified by histological subtype. For the hypothesis test, we considered p < 0.05 to be statistically significant; all tests were two-sided. All data were analyzed by the SPSS version 22.0 software (SPSS, Chicago, IL, United States). Results: From a total of 214 patients, 198 patients were included in the survival analysis. The patients were predominantly white (87%), female (50.2%), with a mean age of 63 (SD: 13) without history of smoking (51%). The predominant histology was adenocarcinoma (30%), followed by neuroendocrine neoplasms (NEN) (27%), carcinoma NOS (25%), squamous cell carcinoma (SCC) (10%) and non-classifiable tumors (7%). The median follow-up time was 23 months, and medial OS was 23 months in the entire cohort. OS by histology was as follows: 51 months for NEN, 34 months for SCC, 18 months for carcinomas NOS and 11 months for adenocarcinomas (p < 0.001) (fig.1). Similar OS trends were observed when we restricted the analysis to poorly differentiated tumors. The 3- and 5-year cumulative survival by histology were as follows: 7% and 0% for adenocarcinoma, 25% and 8% for carcinoma NOS, 39% and 17% for SCC, and 56% and 22% for NEN. In Cox regression models we did not identify any prognostic factors among patients with adenocarcinoma. Conclusions: Patients with adenocarcinoma of unknown primary possess a considerable challenge and the OS is short. CUP of other histologies have higher OS. This study highlights the need of accurate tumor identification and better treatment, perhaps as a multiomics therapeutic approach.

AbstractCheckpoint inhibitor (CPI) therapy with anti–PD-1 antibodies has been associated with mixed outcomes in small cohorts of patients with relapsed aggressive B-cell lymphomas after CAR-T failure. To define CPI therapy efficacy more definitively in this population, we retrospectively evaluated clinical outcomes in a large cohort of 96 patients with aggressive B-cell lymphomas receiving CPI therapy after CAR-T failure across 15 US academic centers. Most patients (53%) had diffuse large B-cell lymphoma, were treated with axicabtagene ciloleucel (53%), relapsed early (≤180 days) after CAR-T (83%), and received pembrolizumab (49%) or nivolumab (43%). CPI therapy was associated with an overall response rate of 19% and a complete response rate of 10%. Median duration of response was 221 days. Median progression-free survival (PFS) and overall survival (OS) were 54 and 159 days, respectively. Outcomes to CPI therapy were significantly improved in patients with primary mediastinal B-cell lymphoma. PFS (128 vs 51 days) and OS (387 vs 131 days) were significantly longer in patients with late (&gt;180 days) vs early (≤180 days) relapse after CAR-T. Grade ≥3 adverse events occurred in 19% of patients treated with CPI. Most patients (83%) died, commonly because of progressive disease. Only 5% had durable responses to CPI therapy. In the largest cohort of patients with aggressive B-cell lymphoma treated with CPI therapy after CAR-T relapse, our results reveal poor outcomes, particularly among those relapsing early after CAR-T. In conclusion, CPI therapy is not an effective salvage strategy for most patients after CAR-T, where alternative approaches are needed to improve post–CAR-T outcomes.

Immune checkpoint inhibitors (ICIs) and brentuximab vedotin (BV) are novel agents for classic Hodgkin lymphoma, including relapse after autologous stem cell transplant (ASCT). However, their impact on survival post-ASCT relapse, in comparison with conventional therapy, is less known due to the lack of randomized controlled trials. Clinical characteristics and outcomes of 115 patients with relapse (or progression) after ASCT are studied. After a median follow-up of 8.59 years from post-ASCT relapse, the median progression-free survival (PFS) and overall survival (OS) were 0.91 and 5.07 years, respectively. Median lines of therapy after post-ASCT relapse was 2 (range, 1–12). The median PFS was not reached (NR) versus 1.11 versus 0.50 versus 0.85 versus 0.78 years (P = 0.006) and OS was NR versus 7.60 versus 3.08 versus 3.51 versus 3.17 years (P = 0.28) in patients first treated with ICIs versus BV versus investigational agents versus chemotherapy versus radiation therapy (RT). First-line treatment with novel agents (ie, ICIs and BV) was associated with superior outcomes compared with investigational agents and chemotherapy/RT with a median PFS of 1.65 versus 0.50 versus 0.79 years (P = 0.003) and a median OS of 7.60 versus 3.08 versus 3.32 years (P = 0.08). Regardless of lines of therapy, the treatment with ICIs had the most favorable outcome with a median PFS and OS of 3.98 and NR years, respectively. Allogeneic stem cell transplant (allo-SCT) was done in 23 patients (20%), and the median post-allo-SCT PFS and OS were 1.31 and 2.35 years, respectively. In conclusion, survival following post-ASCT relapse improves significantly when patients receive novel agents.

AbstractBackgroundIt is unknown whether serum procalcitonin (PCT) concentration monitoring can differentiate between bacterial infection or cytokine release syndrome (CRS) when chimeric antigen receptor T‐cell (CAR‐T) recipients present with a constellation of signs and symptoms that may represent both complications.ObjectiveThe objective of the study was to assess the utility of serum PCT concentrations as a biomarker of bacterial infection in CAR‐T recipients.Study designThis single‐center, retrospective, medical record review evaluated patients prescribed CAR‐T therapy until death or 30 days after infusion. Logistic regression modeling determined the association between elevated serum PCT concentrations within 48 h of fever onset and microbiologically confirmed infection. Secondary outcomes included clinically suspected infection, CAR‐T toxicity rates, and broad‐spectrum antibiotic usage. Predictive performance of PCT was assessed by area under the receiver operating characteristic curve (AUC).ResultsThe 98 included patients were a median age of 63 (IQR: 55–69) years old, 47 (48%) were male, and 87 (89%) were Caucasian. Baseline demographics and clinical characteristics were similar between patients with and without a bacterial infection. Serum PCT >0.4 ng/mL within 48 h of fever was significantly associated with a microbiologically confirmed bacterial infection (OR: 2.75 [95% CI: 1.02–7.39], p = 0.045). Median PCT values in patients with and without confirmed infections were 0.40 ng/mL (IQR: 0.26, 0.74) and 0.26 ng/mL (IQR: 0.13, 0.47), respectively. The AUC for PCT to predict bacterial infection was 0.62 (95% CI 0.48–0.76). All patients experienced CRS of some grade, with no difference in CRS severity based on elevated PCT. Broad‐spectrum antibiotics were used for a median of 45% and 23% of days in those with and without confirmed infection, respectively (p = 0.075).ConclusionElevated serum PCT concentrations above 0.4 ng/mL at time of first fever after CAR‐T infusion was significantly associated with confirmed bacterial infection. Furthermore, rigorous, prospective studies should validate our findings and evaluate serial PCT measurements to optimize antimicrobial use after CAR‐T therapy.

Abstract The tumor microenvironment (TME) plays a crucial role in mediating the tumor immune response, thereby affecting patient outcomes in follicular lymphoma (FL). Using CyTOF, we analyzed a cohort of 82 FL patients with biopsy specimens collected before the first treatment regimen was administered. Our results showed that there was a difference in the T-cell phenotype in patients with various TMEs. Patients with TMEs rich in monocyte/macrophages/NK cells had more CD8+ cells and tended to have fewer TN, but more TEMRA and TEXH cells. Patients enriched with T cells exhibited a T-cell phenotype skewed toward to TCM and patients with B cell dominance tended to have significant higher number of TFH cells. T-cell phenotypes with more terminally differentiated, senescent and exhausted cells were highly represented in patients with less T cells when compared to patients with more T cells. We observed that CD57+ TFH cells was significantly more abundant in patients who had disease progression than patients who had complete response to therapy, suggesting a role for CD57+ TFH cells in promoting malignant cell growth in FL. Consistent with this finding, we observed that increased numbers of CD57+ TFH cells correlated with an inferior survival in FL. Using CITE-seq technology, we found that CD57+ TFH cells exhibited a substantially different transcriptome from CD57− TFH cells. Genes that were differentially upregulated in CD57+ TFH cells when compared to CD57− TFH cells included genes involved in cell survival, compromised inflammatory response, and metabolic activation. Taken together, our results indicate different tumor microenvironments among patient groups that is associated with variable T-cell phenotypes.

Abstract T cell Ig and ITIM domain (TIGIT) is an immune checkpoint molecule and its ligation delivers an inhibitory signal to T cells that negatively regulates anti-tumor responses. However, the expression and biological relevance of TIGIT in B-cell non-Hodgkin lymphoma (NHL) is completely unknown. To phenotypically characterize TIGIT+ T cell subsets, we profiled TIGIT-expressing CD4+ and CD8+ T cells from biopsy specimens of B-cell NHL. TIGIT expression was not detectable on T cells from peripheral blood, however, TIGIT is constitutively expressed on CD4+ T cells from biopsy specimens of B-cell NHL with a median of 44.8% (range: 25.9–62.2, n=8) of CD4+ T cells expressing TIGIT. By profiling the CD4+TIGIT+ T cells, we observed that CD25 was highly expressed on intratumoral CD4+TIGIT+ T cells. Intracellular staining revealed that Foxp3 was expressed by intratumoral CD4+TIGIT+ T cells. These intratumoral CD4+TIGIT+ T cells expressed high level of chemokine receptor CCR4 and were absent of IL-7 receptor-α (CD127). Functionally, CD4+TIGIT+ T cells displayed reduced cytokine production, as the number of IFN-γ- and TNF-α-producing cells was lower in the TIGIT+ population than in TIGIT− T cells. While TIGIT expression can be induced by TCR activation, treatment of T cells with IL-2 and TGF-β inhibited TCR-mediated TIGIT induction. Furthermore, lymphoma B cells were involved in TIGIT induction as in vitro depletion of lymphoma B cells altered upregulation of TIGIT on CD4+ T cells in B-cell NHL. Taken together, these results indicated that constitutive expression of TIGIT defines a CD4+ population with similar phenotype to regulatory T cells. Inhibition of TIGIT signaling may be an additional mechanism to prevent T-cell suppression in B-cell NHL