Citations

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.

6589 Background: Real-world utilization and comparative effectiveness of direct oral anticoagulants (DOACs), low molecular weight heparin (LMWH) and warfarin for cancer-associated venous thromboembolism (VTE) treatment remains largely unexplored. Methods: De-identified administrative claims data (OptumLabs - Data Warehouse) for adult active cancer patients with acute VTE (1/1/2012-9/30/2019) were assessed for utilization patterns, recurrent VTE, and major bleeding differences between DOACs, LMWH, and warfarin. Patients were followed up till the end of treatment. Patients who crossed over to other anti-coagulants within the follow up period were excluded. Multinomial logistic regression was used to assess predictors of anticoagulant administration. Kaplan-Meier curves were used to evaluate the differences in time to medication discontinuation among the three groups. Propensity score (PS) and inverse probability of treatment weighting were used to balance baseline differences between groups. Standardized difference (SD) was used to assess the balance of covariates after weighting and SD < 10% was considered acceptable. Weighted Cox proportional hazards regression with a robust variance estimator was then used to assess outcomes in PS weighted groups. Results: A total of 5100 patients met the inclusion criteria; 49.3% filled DOACs (n = 2512), 29.2% LMWH (n = 1488), and 28.6% warfarin (n = 1460). Median treatment duration was around 3.2 months for DOACs and warfarin, and 1.8 months for LWMH ( P-value < 0.01). Multinomial regression analysis showed that younger patients were more likely to be prescribed LMWH (OR 0.97 95% CI: 0.97-0.98) as compared to DOACs. Patients with lung (OR 2.07 95% CI: 1.12-3.65; OR 1.87 95% CI: 1.04-3.37), urological (OR: 1.94 95% CI:1.08-3.49; OR: 2.04 95% CI: 1.12-3.73), gynecological (OR 4.25, 95% CI: 2.31-7.82; OR 2.31 95% CI: 1.22-4.39) and colorectal cancer (OR 2.26 95% CI: 1.20-4.32; OR 2.51; 95% CI: 1.32-4.79) were more likely to be prescribed LMWH or warfarin respectively, compared to DOACs. VTE recurrences were more frequent for patients receiving LMWH (HR: 1.47; 95% CI: 1.14-1.90) or warfarin (HR: 1.46; 95% CI: 1.13-1.87) compared to DOACs. LMWH, but not warfarin, was associated with greater major bleeding rates compared to DOACs (HR: 2.27; 95% CI: 1.62-3.20). All-cause mortality rates were also significantly higher for patients receiving LMWH, but not warfarin compared to DOACs (HR: 1.61; 95% CI: 1.15-2.25). Conclusions: Patients with cancer associated VTE remain on anti-coagulation for a remarkably short duration in real-world clinical practice. DOACs and warfarin may offer better compliance than LMWH. Patients receiving DOACs have a lower risk of VTE recurrence, less major bleeding, and improved mortality. Warfarin may still be considered for patients with contraindications to DOACs and non-compliant to LMWH.

TPS6111 Background: Treatment options for recurrent and/or metastatic (R/M) salivary gland cancer (SGC) are limited with response rates to standard cytotoxic chemotherapy (CT) low at 10-30%, and responses to single-agent immune checkpoint inhibition (ICI) <10%. Current therapeutic agents used to treat R/M SGC have an unfavorable toxicity profile including cytotoxic CTs such as cisplatin and doxorubicin and the targeted therapy lenvatinib. Treatments with general applicability and acceptable side effect profile are urgently needed. Pemetrexed (PTX) is a multi-targeted anti-folate CT with an excellent safety and toxicity profile with promising responses reported in a case series of patients (pts) with R/M SGC (Viscuse P and Price K. Marked responses to pemetrexed chemotherapy for metastatic adenocarcinoma of the parotid gland: case series. Head Neck 2019;41(6):E99-103.). As the combination of PTX and pembrolizumab (PMB) showed enhanced responses and survival in pts with lung cancer, we hypothesize that PTX and PMB will have efficacy in pts with R/M SGC and that the combination will have improved anti-cancer activity compared with historical controls. Correlative studies on archived tissues include methylthioadenosine phosphorylase loss, PDL1 expression, and thymidylate synthase expression as potential biomarkers of response. Methods: MC200708 is a single institution (3-site), open-label, single arm phase II study of PTX and PMB in patients with R/M SGC. Pts will be treated in two cohorts: one for pts with adenoid cystic carcinoma (ACC) and the other for pts with all other types of SGC (non-ACC cohort). Eligible pts must be ≥18 years old, have a pathologically confirmed SGC that is not amenable to curative-intent therapy, ECOG 0-2, adequate organ function, and at least 1 measurable lesion by RECIST 1.1. Any number of lines of prior therapy is allowed; prior treatment with checkpoint inhibitors and/or PTX is allowed. Key exclusion criteria: serious medical co-morbidity or autoimmune disease, prior grade 3-4 adverse event (AE) or grade 2-4 lung AE with ICI, and uncontrolled brain metastases. Simon’s two-stage design will be used for each cohort separately given the expected difference in responses in pts with ACC and non-ACC. Primary endpoint is overall response rate. Secondary endpoints are progression free and overall survival and toxicity. All patients will receive the same treatment of PTX 500 mg/m2 IV + PMB 200 mg IV every 3 weeks until disease progression or treatment intolerance. Response assessments will occur every 3 cycles. Enrollment began July 2021 and 16 of the planned 45 patients (ACC cohort 9 of 20 pts, non-ACC 7 of 25) have been accrued. Clinical trial information: NCT04895735.

e15118 Background: Melanoma, non-small cell lung cancer (NSCLC), colorectal adenocarcinoma and thyroid tumors frequently harbor BRAF mutations and are tumor types eligible for treatment with FDA-approved BRAF inhibitors. Although there are many ongoing clinical trials with BRAF inhibitors in various advanced tumor types, currently eligibility requires both tumor type identification and BRAF mutation confirmation. The 92-gene assay (CancerTYPE ID) is a gene expression-based classifier of 50 tumor types and subtypes for metastatic patients with diagnostic ambiguity. Multimodal biomarker testing, including NGS, IHC and FISH, enables identification of actionable biomarkers to guide targeted therapy selection. Here, a database of metastatic cases integrating tumor type with biomarker analysis was used to identify patients eligible for BRAF inhibitor treatment. Methods: MOSAIC (Molecular Synergy to Advance Individualized Cancer Care) is an IRB-approved, de-identified database of diagnostically ambiguous cases submitted for CancerTYPE ID testing with tumor type-guided multimodal biomarker testing (Neogenomics). In this study, metastatic cancers of various tumor types with BRAF mutations were identified. Results: CancerTYPE ID determined 27 different tumor types in 2929 (92.5%) of 3168 cases. BRAF mutations were identified in 87 cases across 18 tumor types and subtypes. Out of the 87 cases, 22 (25.3%) had BRAF mutations in a tumor type eligible for FDA-approved BRAF inhibitor treatment, including melanoma, NSCLC, colorectal adenocarcinoma and thyroid cancer. Another 26 (29.9%) BRAF-mutated cases were detected in a tumor type with ongoing BRAF inhibitor clinical trials, including lymphoma, pancreaticobiliary and ovarian cancer (Table). Conclusions: This analysis identified patients with metastatic cancer with actionable BRAF mutations eligible for FDA-approved therapy, and patients who may be eligible for investigational BRAF inhibitors based on tumor type and mutation status. Notably, cancer type identification is critical given that FDA-approved BRAF inhibitor treatment regimens vary based on the tumor-specific indication. These findings support the clinical utility of molecular tumor type classification by CancerTYPE ID combined with biomarker profiling to identify additional treatment options for patients with metastatic cancer.[Table: see text]

Abstract Context Metastatic pheochromocytomas and paragangliomas (mPPGL) are rare vascular neuroendocrine tumors that highly express vascular growth factors. Systemic treatment options in cases of unresectable multisite disease are limited. Multikinase inhibitors that inhibit angiogenesis, such as lenvatinib, have proven effective in several other malignancies, and may be a viable option for mPPGL. Objective We aimed to evaluate the efficacy of lenvatinib as salvage therapy in mPPGLs. Methods This was a retrospective analysis of mPPGL patients ≥ 18 years of age who received lenvatinib from 2015 to 2020 at a tertiary referral center. Patients were started on lenvatinib 20 mg daily and dose was adjusted according to tolerance or disease progression. Results Eleven patients were included. Median treatment duration was 14.7 months (95% CI, 2.3-NE). Treatment was discontinued due to disease progression, adverse events, or death. Overall survival at 12 months was 80.8% (95% CI, 42.3-94.9%) but its median was not reached. Median progression-free survival was 14.7 months (95% CI, 1.7-NE). Among the 8 patients with measurable disease, overall response rate was 63%, as 5/8 experienced a partial response and 3/8 had stable disease. Worsening hypertension and anemia were the most common adverse events. Conclusion Lenvatinib may be a viable treatment option for mPPGL, although at the potential risk of worsening hypertension. Larger, multicenter studies are needed to better characterize treatment efficacy.