Gile, Jennifer

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.

Abstract Poorly differentiated extrapulmonary neuroendocrine carcinomas (EP NECs) are aggressive cancers characterized by a high Ki‐67 index, rapid tumor growth and poor survival, and are subdivided into small and large cell carcinoma. For small cell carcinoma of the lung, a pulmonary NEC, the combination of cytotoxic chemotherapy (CTX) and a checkpoint inhibitor (CPI) is considered standard therapy and superior to CTX alone. EP NECs are typically treated with platinum‐based regimens, some clinicians have adopted the addition of a CPI to CTX based on data from trials in patients with small cell carcinoma of the lung. In this retrospective study of EP NECs, we report 38 patients treated with standard first‐line CTX and 19 patients treated with CTX plus CPI. We did not observe any additional benefit of adding CPI to CTX in this cohort.

559 Background: Cabozantinib, a multikanase inhibitor, is approved by the Food and Drug Administration (FDA) for treatment of advanced stage hepatocellular carcinoma (HCC) following progression on sorafenib. The CELESTIAL study which demonstrated benefit from cabozantinib following sorafenib included only patients with Child Pugh class A liver function. Recently, bevacizumab plus atezolizumab has replaced sorafenib as the first line treatment for HCC. It is unclear whether there is benefit from using Cabozantinib following progression on immunotherapy as CELESTIAL trial included very few patients who received prior immunotherapy. We describe the outcomes of individuals with advanced stage HCC treated with Cabozantinib following progression on immunotherapy. Methods: This was a multicenter, retrospective analysis of patients with advanced HCC diagnosed between 2010-2021 at Mayo Clinic Arizona, Florida, and Minnesota. Progression free survival (PFS) and median overall survival analysis were performed using Kaplan-Meier method. Results: We identified a total of 26 patients with advanced stage HCC who received cabozantinib following progression on immunotherapy. The median age of patients was 61 years (range, 39 – 81) and the majority were male (85%). Eighteen (72%) patients had Child Pugh A at initiation of cabozantinib therapy. Four (15%) patients received cabozantinib as second line therapy, the rest received it as third line or later. PFS on cabozantinib was 2.1 months (95% CI: 1.3 – 3.9) and median overall survival from time of cabozantinib initiation was 7.7 months (95% CI: 5.3 – 14.9). PFS was shorter with Child Pugh Class B, 1.3 months (95% CI: 0.9 – NE) compared to those with Child Pugh Class A, 2.1 months (95% CI: 1.5 – 4); although this difference was not significant (p=0.55). Common adverse events included fatigue (50%), anorexia (35%), aspartate aminotransferase (AST) elevation (35%), and diarrhea (31%); 7 (26%) patients experienced Grade 3 or greater adverse events including hypertension, diarrhea, anorexia, and bowel obstruction. Two patients discontinued cabozantinib due to side effects including one for uncontrolled blood pressure elevations and the other due to fatigue. Conclusions: The optimal sequencing of therapy for patients with advanced HCC following progression on immunotherapy is unknown. Treatment with cabozantinib may improve clinical outcomes following progression on immunotherapy with similar adverse event profile. This study included patients with Child Pugh class B liver disease (28%) and heavily pretreated population and demonstrated mPFS and mOS similar to other work examining outcomes of cabozantinib in real world setting after progression on sorafenib. Further studies to determine optimal treatment sequencing for this patient population are needed.

507 Background: Lenvatinib, a multikinase inhibitor, is an FDA approved treatment for advanced hepatocellular carcinoma (HCC) in the first line setting. Atezolizumab and bevacizumab are considered new standard of care as first line therapy after results of the IMBrave 150 trial. Currently, we do not have data to suggest any second-line treatment after administration of immunotherapy. We describe the clinical outcomes in patients with advanced HCC who received lenvatinib following treatment with immunotherapy. Methods: We conducted a multicentric, retrospective analysis of patients with advanced HCC diagnosed between 2010 and 2021 at Mayo Clinic in Minnesota, Arizona, and Florida. The study was reviewed and approved by the intuitional review board. The primary outcomes were overall survival (OS) and progression free survival (PFS). Results: We identified 53 patients with advanced HCC who received lenvatinib following immunotherapy. Most patients (83%) were male. Median age at start of lenvatinib was 67 years old. Forty-two (79%) patients had a Child-Pugh score of A at diagnosis while 30 (58%) patients were still Child-Pugh A at time of lenvatinib initiation. Risk factors for HCC included Hep C (43%), alcohol use (34%), NASH (15%) and hepatitis B (7%). Forty-five (85%) patients received lenvatinib in the 2nd line and 8 (15%) patients received it as third line or later. At time of data extraction, 38 (72%) patients had died. Median PFS was 4 months (95% CI: 3 – 6) and median OS from time of lenvatinib initiation was 13 months (95% CI: 6 – 24). The most common adverse events of any grade included fatigue (53%), hypertension (37%), AST elevation (30%), anorexia (28%), bilirubin elevation (25%) and diarrhea (25%). Twenty-one (40%) patients experienced grade 3 or higher adverse events including hypertension (25%), confusion (6%), acute kidney injury (2%), hyperkalemia (2%), ALT elevation (2%), proteinuria (2%), arthralgia (2%), heart failure (2%), AST elevation (2%), bilirubin elevation (2%), palmar-plantar erythrodysesthesia (2%), oral mucositis (2%), weight loss (2%), hypothyroidism (2%), anorexia (2%), fatigue (2%) and diarrhea (2%). Seven patients stopped treatment due to adverse events: 1 for hypertension, 2 for confusion, 1 for heart failure, 2 for fatigue, and 1 for elevated bilirubin. Conclusions: The optimal sequencing of therapy for patients with advanced HCC following progression on immunotherapy remains unknown. We found that median OS was 13 months in patients who received lenvatinib after immunotherapy which is comparable to survival in other studies when used as first line therapy. Our experience demonstrates that patients may benefit from treatment with lenvatinib following initial progression on immunotherapy.

Abstract Background Isavuconazole (ISA) is a relatively recent triazole antifungal with several attractive qualities and so increased clinical experience and data on the use of ISA are desirable. However, the data on the pattern of ISA use in invasive fungal infections (IFI) is limited. Methods We conducted a retrospective study of patients with probable or proven IFI treated with ISA at Mayo Clinic from 1/1/2015 to 4/1/2020 to examine temporal trends and characteristics of ISA use. Results The use of ISA rose over this period, from 4 cases in 2015 to 42 cases in 2019. Of 131 patients identified, ISA was used as the initial antifungal in 15 (11.5%) patients and as the secondary agent in 116 (88.5%) patients. The most cited reasons for choosing ISA as first-line therapy were drug-drug interactions (5, 33%) and baseline QTc prolongation (3, 20%). In cases of ISA used as a secondary agent, the reasons for transitioning to ISA were QTc prolongation (22, 19%), followed by judged failure of the primary therapy (20, 17%), drug-drug interactions (12, 10%), and various toxicities with the first agent. ISA was discontinued early in 81 (62%) patients. Common reasons for early discontinuation were patient death or comfort care (27, 33%), intolerance (18, 22%), failure of therapy (17, 21%), cost or access (6, 7%), drug-drug interaction (3, 4%), issues with absorption or drug delivery (3, 4%), and microbe susceptibility (1, 1%). ISA was judged successful and used as definitive treatment in the remaining 50 (38%) patients. About 30 patients took &gt;1 year of ISA, and no major adverse effects from long-term therapy were noted. Conclusion Although ISA is approved for pulmonary aspergillosis and mucormycosis, we found that few patients were treated with ISA as either primary or salvage therapy. In cases where it was used, shortening the QTc and fewer drug-drug interactions were its most attractive qualities. Although it is a newer azole, the morbidity common with other antifungals should prompt more studies on ISA’s efficacy to increase clinicians’ confidence in this option. Disclosures All Authors: No reported disclosures.