Tumor biology and immune infiltration define primary liver cancer subsets linked to overall survival after immunotherapy

Primary liver cancer is a rising cause of cancer deaths in the US. Although immunotherapy with immune checkpoint inhibitors induces a potent response in a subset of patients, response rates vary among individuals. Predicting which patients will respond to immune checkpoint inhibitors is of great interest in the field. In a retrospective arm of the National Cancer Institute Cancers of the Liver: Accelerating Research of Immunotherapy by a Transdisciplinary Network (NCI-CLARITY) study, we use archived formalin-fixed, paraffin-embedded samples to profile the transcriptome and genomic alterations among 86 hepatocellular carcinoma and cholangiocarcinoma patients prior to and following immune checkpoint inhibitor treatment. Using supervised and unsupervised approaches, we identify stable molecular subtypes linked to overall survival and distinguished by two axes of aggressive tumor biology and microenvironmental features. Moreover, molecular responses to immune checkpoint inhibitor treatment differ between subtypes. Thus, patients with heterogeneous liver cancer may be stratified by molecular status indicative of treatment response to immune checkpoint inhibitors.

Detection of DNA adduct γ-OHPdG in circulating tumor cells (CTCs) and its use as a prognostic biomarker in patients with hepatocellular carcinoma (HCC)

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Background: A blood-based biomarker to predict the risk of hepatocellular carcinoma (HCC), and its recurrence is needed. Previously, we showed that γ-OHPdG, a mutagenic DNA adduct formed by lipid peroxidation, in liver biopsies from HCC patients, as detected by IHC, is inversely associated with overall survival (p<0.0001) and recurrence-free survival (p<0.007) after surgical resection. This finding suggests that γ-OHPdG may serve as a prognostic biomarker of HCC and its recurrence. A non-invasive method to detect γ-OHPdG is needed. Liquid biopsy is preferred over tissue biopsy because it is non-invasive, allows repeated sampling, lower risk to patient, and lower medical care cost. We developed a non-invasive method for detecting and quantifying γ-OHPdG using CTCs from HCC patient. Methods: The method involved following steps. First, CTCs from blood samples were isolated using a RosetteSep CD45 Depletion Cocktail and Ficoll Paque-based method. Isolated cells were identified as liver CTCs using asialoglycoprotein receptor 1 (ASGPR1), a cell surface protein expressed solely on the surface of hepatic cells, and γ-OHPdG by immunocytochemistry. The percentage of ASGPR1 and γ-OHPdG-positive stained CTCs and γ-OHPdG staining intensity was quantified using Metamorph software. The staining intensities in livers CTCs will be compared with that found in liver biopsies by IHC. Results: To determine the sensitivity and specificity of testing -γ-OHPdG level in circulating tumor cells using an-anti γ-OHPdG antibody, we showed that the proportion of γ-OHPdG-positively stained cells and staining intensity increased in HepG2 liver cancer cells upon acrolein treatment at increasing concentration. Furthermore, when the HepG2 was used to spike blood of healthy volunteers’, the recovery rate of γ-OHPdG positivity was > 50-60%. CTCs from 32 HCC patients, detected at a positivity rate of ~97%, were tested for γ-OHPdG levels using the method developed in this project. The clinical factors including demographics, risk factors, alpha-fetoprotein (AFP), HCC size, multifocality, vascular invasion, extrahepatic metastasis have been correlated with the levels of γ-OHPdG in CTCs. Conclusions: The CTC method developed for detecting and quantifying γ-OHPdG warrant validations as a prognostic biomarker for predicting HCC risk and recurrence in clinical trials.

EXTH-81. ITGA5 IS A NOVEL IMMUNOTHERAPEUTIC TARGET AGAINST TREATMENT REFRACTORY MEDULLOBLASTOMA

Medulloblastoma (MB) is the most common type of malignant pediatric brain cancer. Current standard of care (SOC) involves maximal safe resection and neuraxis radiotherapy and chemotherapy in individuals older than 3 years. To date, these cytotoxic SOC combined with craniospinal irradiation led to devastating neurocognitive and developmental deficits impacting quality of life for pediatric patients. The biological heterogeneity of MB is highlighted by the existence of four distinct molecular subgroups (WNT, SHH, Group 3, and Group 4). Group 3 and Group 4 have the poorest patient outcomes because of their aggressive, metastatic nature, and so often remain treatment refractory to SOC. Group 3 has a poor prognosis due to its high incidence of leptomeningeal spread and an overall survival rate of less than 50%. The cytotoxic nature and lack of response in specific subtypes to SOC underscores the urgent need for developing and translating novel treatment options including immunotherapies. In our earlier work, we have developed a therapy-adapted patient derived xenograft (PDX) model of the Group 3 MB as the tumor cells undergoes therapy in vitro and in vivo. N-glycocapture surfaceome profiling of the MB cells through this PDX model identified Integrin α5 (ITGA5) as one of the most differentially expressed targets found at recurrence when compared to engraftment and untreated timepoints. Through shRNA knockdown and small molecule inhibition, we identify ITGA5 expression marks a MB cell subpopulation with increased self-renewal ability both in vitro and in vivo. Access to recurrent MB (rMB) post-therapy allowed us to investigate the changes in the surfaceome of MB cells using proteomics profiling to identify promising rMB-specific targets for rational development of novel immunotherapies.

Abstract PR009: The functional genomic landscape of recurrent glioblastoma

Glioblastoma (GBM) is a highly fatal brain cancer where mortality is predominantly caused by disease recurrence and lack of second-line therapies. Here, utilizing genome-wide CRISPR-Cas9 screening, we uncover treatment-based conditional genetic interactions modulating sensitivity to combined radiation therapy (RT) and temozolomide (TMZ), the standard of care treatment administered to over 70% of glioblastoma patients. To investigate therapy-induced changes in the functional landscape of glioblastoma stem cells (GSCs) without confounding patient-to-patient differences, we systematically mapped genetic dependencies in patient-matched pre-treatment primary and post-treatment recurrent GSCs. This comparison highlights a remodelling of genes and pathways regulating tumor cell survival at disease relapse, arming recurrent GSCs with newly acquired genetic drivers and further loss of tumor suppressors. Among these genes, we identify PTP4A2, encoding protein tyrosine phosphatase 4A2, as a major regulator of stemness and tumorigenicity in recurrent GSCs. Genetic perturbation or pharmacological inhibition of PTP4A2 influences the phosphorylation status and expression of interacting proteins belonging to axonal guidance pathways, as phosphoproteomic studies showed specific enrichment in axon guidance regulator Roundabout Guidance Receptor 1 (ROBO1) in recurrent GSCs. We therefore designed and developed efficacious Camelid biotinylated single-domain antibody (bio-sdAb) and tetrameric complexes targeting human ROBO1 (MKRo-20). Subsequently, we orthotopically engrafted recurrent GSCs into immunocompromised mice and administered local treatments of tetrameric MKRo-20. All mice treated with tetrameric MKRo-20 were rendered tumor free, suggesting that modulation of ROBO1 with bio-sdAbs presents a new immunotherapeutic strategy to target recurrent glioblastoma. Our work reveals a context-specific dependence on axonal guidance through a PTP4A2-ROBO axis in recurrent glioblastoma, highlighting new avenues of therapeutic intervention for second-line therapy in GBM.

This abstract is also being presented as PO025.

Citation Format: Chirayu Chokshi, David Tieu, Kevin Brown, Chitra Venugopal, Lina Liu, Laura Kuhlman, Katherine Chan, Amy Tong, Neil Savage, Dillon McKenna, Nikoo Aghaei, Minomi Subapanditha, Joseph M Salamoun, Martin Rossotti, Peter Wipf, Elizabeth Sharlow, John S. Lazo, Thomas Kislinger, Kevin Henry, Yu Lu, Jason Moffat, Sheila K. Singh. The functional genomic landscape of recurrent glioblastoma [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PR009.

Analgesic efficacy and safety of nefopam vs. propacetamol following hepatic resection

In order to compare the morphine-sparing effect, analgesic efficacy and tolerance of nefopam and propacetamol given at their highest recommended doses, 120 patients undergoing elective hepatic resection were randomly assigned to receive postoperative intravenous patient-controlled analgesia with morphine alone, or in combination with nefopam (20 mg.4 h-1) or propacetamol (2 g.6 h-1). Compared with the control group (43 [7-92] mg), median [range] cumulative morphine consumption for 24 h after the study started was halved in the nefopam group (21 [3-78] mg, p <0.001) and 20% lower in the propacetamol group (35 [6-84] mg, p = 0.15). Analgesia was superior in the nefopam group despite the lower morphine consumption. Adverse effects were comparable in the three groups, except for significantly more nausea in the control group (39% vs. 17 and 26% in the nefopam and propacetamol groups, respectively) and more sweating in the nefopam group (17% vs. 0 and 3% in the control and propacetamol groups, respectively). Overall patient satisfaction was better (p < 0.001) in patients given nefopam (97%) than those receiving morphine alone (82%) or propacetamol (74%).

Management of peri-operative pulmonary hypertension in a patient presenting for a portosystemic shunt

We report the successful management of intra-operative pulmonary hypertension in a patient with mitral valve insufficiency and portal hypertension. A 48-year-old male with portal hypertension presented for a portosystemic shunt. Previously undiagnosed mitral valve insufficiency and pulmonary hypertension complicated his anaesthetic management. His intra-operative course was marked by systolic hypotension, pulmonary hypertension and a reduction in cardiac output. The use of nitric oxide in this patient reduced right ventricular afterload, increased cardiac output, without exacerbating pre-existing systolic hypotension.

[Hemodynamic effects of the induction of general anesthesia after low thoracic epidural anesthesia]

Sixteen ASA 1 or 2 patients scheduled for abdominal surgery were included in the study after they had given their informed consent. Thirty minutes after starting a low-thoracic epidural anaesthesia (median level of sensitivity loss: T5), the patients were randomly given an intravenous bolus injection of either thiopentone (4 mg.kg-1, n = 8) or etomidate (0.5 mg.-1, n = 8), associated with succinylcholine 1 mg.kg-1. One minute after induction of general anaesthesia, the patients were intubated and mechanically ventilated (V(T) 8 ml.kg-1, rate 12 c.min-1). Mean arterial blood pressure (MAP) (oscillometric method), cardiac output (CO) (transthoracic bioimpedance) and heart rate were recorded semi-continuously. Total peripheral resistances (TPR) were calculated using the formula TPR = (MA/CO)*80. There were no differences between the groups in patient age, height, weight, and cardiovascular consequences of epidural anaesthesia. After anaesthetic induction and before endotracheal intubation, there was a slight decrease in CO in both groups, without any change in MAP. After intubation, MAP increased in both groups through peripheral vasoconstriction, whereas CO did not increase further. A significant tachycardia was occurred only seen in the thiopentone group, before and after tracheal intubation. This study showed that thiopentone and etomidate were suitable drugs for anaesthetic induction in a patient under epidural blockade. However, the absence of tachycardia following etomidate may be beneficial in cardiac patients. The monitoring of cardiac output determinants during thiopentone and etomidate anaesthesia require further invasive investigations.