Background In patients with cirrhosis, portal hypertension increases intestinal permeability, dysbiosis, and bacterial translocation, promoting an inflammatory state that can lead to the progression of liver disease and development of hepatocellular carcinoma (HCC). We aimed to investigate whether beta blockers (BBs), which can mediate portal hypertension, conferred survival benefits in patients treated with immune checkpoint inhibitors (ICIs). Methods We conducted a retrospective, observational study of 578 patients with unresectable HCC treated with ICI from 2017 to 2019 at 13 institutions across three continents. BB use was defined as exposure to BBs at any time during ICI therapy. The primary objective was to assess the association of BB exposure with overall survival (OS). Secondary objectives were to evaluate the association of BB use with progression-free survival (PFS) and objective response rate (ORR) according to RECIST 1.1 criteria. Results In our study cohort, 203 (35%) patients used BBs at any point during ICI therapy. Of these, 51% were taking a nonselective BB. BB use was not significantly correlated with OS (hazard ratio [HR] 1.12, 95% CI 0.9-1.39, P = 0.298), PFS (HR 1.02, 95% CI 0.83-1.26, P = 0.844) or ORR (odds ratio [OR] 0.84, 95% CI 0.54-1.31, P = 0.451) in univariate or multivariate analyses. BB use was also not associated with incidence of adverse events (OR 1.38, 95% CI 0.96-1.97, P = 0.079). Specifically, nonselective BB use was not correlated with OS (HR 0.94, 95% CI 0.66-1.33, P = 0.721), PFS (HR 0.92, 0.66-1.29, P = 0.629), ORR (OR 1.20, 95% CI 0.58-2.49, P = 0.623), or rate of adverse events (OR 0.82, 95% CI 0.46-1.47, P = 0.510). Conclusion In this real-world population of patients with unresectable HCC treated with immunotherapy, BB use was not associated with OS, PFS or ORR.

BACKGROUND A well-recognized class effect of immune checkpoint inhibitors (ICI) is immune-related adverse events (IrAEs) ranging from low grade toxicities to life-threatening end organ damage requiring permanent discontinuation of ICI. Deaths are reported in < 5% of patients treated with ICI. There are, however, no reliable markers to predict the onset and severity of IrAEs. We tested the association between neutrophil-lymphocyte ratio (NLR) and platelet-lymphocyte ratio (PLR) at baseline with development of clinically significant IrAEs (grade ≥ 2) in hepatocellular carcinoma (HCC) patients treated with ICI. AIM To test the association between NLR and PLR at baseline with development of clinically significant IrAEs (grade ≥ 2) in HCC patients treated with ICI. METHODS Data was extracted from an international database from a consortium of 11 tertiary-care referral centers. NLR = absolute neutrophil count/absolute lymphocyte count (ALC) and PLR = platelet count/ALC. Cutoff of 5 was used for NLR and 300 for PLR based on literature. We also tested the association between antibiotic and steroid exposure to IrAEs. RESULTS Data was collected from 361 patients treated between 2016-2020 across the United States (67%), Asia (14%) and Europe (19%). Most patients received Nivolumab (n = 255, 71%). One hundred sixty-seven (46%) patients developed at least one IrAE, highest grade 1 in 80 (48%), grade ≥ 2 in 87 (52%) patients. In a univariable regression model PLR > 300 was significantly associated with a lower incidence of grade ≥ 2 IrAEs (OR = 0.40; P = 0.044). Similarly, a trend was observed between NLR > 5 and lower incidence of grade ≥ 2 IrAEs (OR = 0.58; P = 0.097). Multivariate analyses confirmed PLR > 300 as an independent predictive marker of grade ≥ 2 IrAEs (OR = 0.26; P = 0.011), in addition to treatment with programmed cell death ligand 1 (PD-1)/cytotoxic T lymphocyte-associated protein-4 (OR = 2.57; P = 0.037) and PD-1/tyrosine kinase inhibitor (OR = 3.39; P = 0.01) combinations. Antibiotic use was not associated with IrAE incidence (OR = 1.02; P = 0.954). Patients treated with steroids had a > 2-fold higher incidence of grade ≥ 2 IrAEs (OR = 2.74; P < 0.001), although 74% were prescribed steroids for the treatment of IrAEs. CONCLUSION Given that high baseline NLR and PLR are associated with a decreased incidence of IrAEs, lower baseline NLR and PLR may be predictive biomarkers for the appearance of IrAEs in HCC treated with ICI. This finding is in keeping with several studies in solid tumors that have shown that baseline NLR and PLR appear predictive of IrAEs.

Atezolizumab plus bevacizumab (Atezo/Bev) is first line-treatment for unresectable hepatocellular carcinoma (HCC). Body mass index (BMI) has demonstrated predictive value for response to immunotherapy in non-HCC cancer types. Our study investigated the effect of BMI on safety and efficacy of real-life use of Atezo/Bev for unresectable HCC. 191 consecutive patients from seven centres receiving Atezo/Bev were included in the retrospective study. Overall survival (OS), progression-free survival (PFS), overall response rate (ORR) and disease control rate (DCR) defined by RECIST v1.1 were measured in overweight (BMI ≥ 25) and non-overweight (BMI < 25) patients. Treatment-related adverse events (trAEs) were evaluated. Patients in the overweight cohort (n = 94) had higher rates of non-alcoholic fatty liver disease (NAFLD) and lower rates of Hepatitis B compared to non-overweight cohort (n = 97). Baseline Child–Pugh class and Barcelona Clinic Liver Cancer stage were similar between cohorts, with lower rates of extrahepatic spread in the overweight group. Overweight patients had similar OS compared to non-overweight (median OS 15.1 vs. 14.9 months; p = 0.99). BMI did not influence median PFS (7.1 vs. 6.1 months; p = 0.42), ORR (27.2

BACKGROUND AND AIMS:Different approaches are available after the progression of disease (PD) to immune checkpoint inhibitors (ICIs) for hepatocellular carcinoma (HCC), including the continuation of ICI, treatment switching to tyrosine kinase inhibitors (TKIs) and cessation of anticancer therapy. We sought to characterise the relationship between radiological patterns of progression and survival post-ICI, also appraising treatment strategies.METHODS:We screened 604 HCC patients treated with ICIs, including only those who experienced PD by data cut-off. We evaluated post-progression survival (PPS) according to the treatment strategy at PD and verified its relationship with radiological patterns of progression: intrahepatic growth (IHG), new intrahepatic lesion (NIH), extrahepatic growth (EHG), new extrahepatic lesion (NEH) and new vascular invasion (nVI).RESULTS:Of 604 patients, 364 (60.3%) experienced PD during observation. Median PPS was 5.3 months (95% CI: 4.4-6.9; 271 events). At the data cut-off, 165 patients (45%) received no post-progression anticancer therapy; 64 patients (17.6%) continued ICI beyond PD. IHG (HR 1.64 [95% CI: 1.21-2.22]; p = .0013) and nVI (HR 2.15 [95% CI: 1.38-3.35]; p = .0007) were associated with shorter PPS. Multivariate models adjusted for progression patterns, treatment line and albumin-bilirubin grade and Eastern Cooperative Oncology Group performance status at PD confirmed receipt of ICI beyond PD with (HR 0.17, 95% CI: 0.09-0.32; p < .0001) or without subsequent TKI (HR 0.39, 95% CI: 0.26-0.58; p < .0001) as predictors of prolonged PPS versus no anticancer therapy.CONCLUSIONS:ICI-TKI sequencing is a consolidated option in advanced HCC. nVI and IHG predict a poorer prognosis. Despite lack of recommendation, the continuation of ICI beyond progression in HCC is adopted clinically: future efforts should appraise which patients benefit from this approach.

Pancreatic cancer (PC) is the fourth leading cause of cancer-related mortality with limited diagnostic and therapeutic options. Although immunotherapy has shown promise in the treatment of several cancers, its role in pancreatic cancer is rather limited. Several studies have focused on determining the role of the tumor microenvironment with cancer-cell-intrinsic events and tumor-infiltrating immune cellular properties. However, in the past decade, there has been emerging research aimed at delineating the role of the host microbiome, including the metabolites from microbes and host responses, on pancreatic tumorigenesis. Importantly, there is emerging evidence suggesting the beneficial role of a gut microbiome transplant to improve immunotherapeutic outcomes in cancer patients. In this review, we summarize the recent understanding of the role of the microbiome in pancreatic cancer progression, along with its clinical diagnostic and therapeutic implications.

e21047 Background: There has been prospective and retrospective evidence for the onset of immunotherapy (IO) related adverse events (irAE) and efficacy of anti programmed death (PD1) and Programmed death Ligand 1(PD L1) antibodies. The incidence of irAE in these studies ranged anywhere from 30-44%. There have been attempts in the past to cluster irAEs into distinct subtypes by T cell profiling before and after immunotherapy. Identifying the trend of CD4/CD8 changes during irAE may aid in finding ways to mitigate the severe toxicities, so the benefits of immunotherapy can be extended to far more number of patients. Methods: We have collected blood samples from 20 patients of Non Small Cell Lung Cancer patients (NSCLC) before each cycle of immunotherapy with informed consent. We have measured the different inflammatory markers such as IL6, IL10 using ELISA and isolated cellular components such as CD4, CD8 T cells along with others using magnetic bead technique, from these samples in our research laboratory at East Carolina University. We have also collected clinical information including the adverse events with their (Common Terminology Criteria for Adverse events) CTCAE 5.0 grading, different cell counts and C- reactive Protein (CRP). Results: In the cohort of 20 patients, 9 experienced irAE, out of which 6 had grade 2, including thyroiditis, pneumonitis, dermatitis, cytokine release syndrome (CRS), 1 had grade 3 pneumonitis, 1 had grade 4 pneumonitis and 1 had grade 1 CRS. When we looked at the CD4/CD8 ratio before each cycle, the one prior to the incidence of the irAE had at least 30-40% drop in the ratio consistently although there were minor fluctuations in the ratio at other times in both directions. Conclusions: Although most irAEs can be treated and reversed with steroids and other immunosuppressive agents, prolonged immunosuppression can lead to reduced efficacy of IO and development of undue opportunistic infections. Experience with IO has shown that earlier initiation of immunosuppression shortens the required treatment. However, given the challenge in the subtility of the earlier presentation, therapies are frequently delayed. Hence, biomarker to identify the early manifestations is of critical importance for early intervention. Studies suggest there is clonal expansion of CD8 T cells preceding grade 2-3 irAEs. Studies also indicate that increased T cells in the tumor is indicative of response to immunotherapy. Our observation suggests that increased CD8 in proportion to CD4 in the peripheral blood precedes the onset of irAE. It is unclear as to how this leads to increased toxicity when the immunotherapy treatment works by affecting T cell function. One possible explanation is that the T cell response in the tumor tissue is beneficial, however, T cell response in the peripheral blood may indicate response against self antigens leading to toxicities in the form of irAE.

399 Background: Portal hypertension increases intestinal permeability, dysbiosis, and bacterial translocation, leading to a pro-inflammatory state, which can in turn promote progression of liver disease. However, multiple studies have shown that BB use in patients with cirrhosis can reduce the risk of developing HCC, and in patients with HCC, BB can improve overall survival (OS). In recent years, ICIs have become first-line therapy for patients with unresectable HCC, and we aimed to evaluate whether BB use conferred survival benefits in patients treated with ICIs using real-world data. Methods: We conducted a retrospective chart review of HCC patients treated with ICI from 2017 to 2019 at 13 institutions across North America, Europe, and Asia in order to evaluate the association between BB use and OS, as well as BB use and overall response rate (ORR). Univariable and multivariable logistic regression models were used to evaluate associations, and survival analyses were performed using the Kaplan-Meier method. Results: A total of 578 patients were evaluated. The median age of the cohort was 65 years, and 80% of patients were male. The majority of patients (70%) were cirrhotic. The causes of underlying liver disease were as follows: HBV (22%), HCV (36%), alcohol (20.8%), and NASH (13%). Most patients (73.5%) had Child Pugh (CP) class A liver disease, and good performance status with ECOG score either 0 (52%) or 1 (45%). The majority of patients (75%) treated with ICIs received a PD-1 inhibitor alone. There were 360 deaths (62% of patients) with a median follow-up of 30.8 months (Quartiles: 17.2-40.3 months). Two hundred and three (35%) patients had BB use at any point during ICI therapy. Fifty-one percent of these patients were on a nonselective BB whereas 49% were taking a cardio-selective BB. BB use was not significantly correlated with OS (hazard ratio, 1.12; 95% CI, 0.9-1.39; P = 0.298) or ORR (odds ratio, 0.84; 95% CI, 0.54-1.31; P = 0.451) in univariate or multivariate analyses. Conclusions: Patients who used BB while on immunotherapy for unresectable HCC did not have statistically significant differences in OS or ORR compared to patients who did not use BB. More studies are required to elucidate the effect of beta blockade on the microbiome, immune activation, and HCC.

Immunotherapy has changed the paradigm of cancer treatment, yet immune checkpoint inhibitors (ICIs) such as PD-1/PD-L1 monoclonal antibodies may cause immune-related adverse events (irAEs) in some patients. In this report, two non-small cell lung cancer (NSCLC) patients treated with nivolumab presented with checkpoint inhibitor-induced thyroid dysfunction (CITD), followed by a second irAE of pneumonitis and intestinal perforation, respectively. Increases in peripheral CD8+ T cells correlated with the onset of CITD in the patients. Intriguingly, common inflammatory biomarkers, including C-reactive protein (CRP) and neutrophil/lymphocyte ratio (NLR), were not consistently increased during the onset of CITD but were substantially increased during the onset of pneumonitis and intestinal perforation irAEs. The observations suggest that unlike other irAEs such as pneumonitis, CRP levels and NLR were non-contributory in diagnosing CITD, whereas T cell expansion may be associated with immunotherapy-induced thyroiditis.

e16204 Background: A well-recognized class effect of immune check point inhibitors (ICI) is IrAEs ranging from low grade toxicities to life-threatening end organ damage requiring permanent discontinuation of ICI. Treatment related deaths are reported in ̃5% of patients (pts) treated with ICI. There are, however, no reliable markers to predict the onset & severity of IrAEs. We tested the association between neutrophil-lymphocyte ratio (NLR) & platelet-lymphocyte ratio (PLR) at baseline with development of clinically significant IrAE (graded ≥2) in HCC pts treated with ICI. Methods: Data was extracted from a large international database from a consortium of 11 tertiary-care referral centers located in the USA, Europe & Asia. NLR=Absolute neutrophil count/ Absolute lymphocyte count (ALC) & PLR=Platelet count/ALC. A cutoff of 5 for was used NLR & 300 for PLR based on literature. We also tested the association between antibiotic & steroid exposure to IrAEs. Results: Clinical data was collected from 361 pts treated between 2016–2020 across the USA (66%), Asia (12%) & Europe (22%) in this multinational database. Most pts received Nivolumab monotherapy (n=318, 74%). 167 (46%) pts developed at least one IrAE, highest grade 1 in 80 (48%), grade ≥2 in 87(52%) pts. Baseline characteristics did not differ significantly between the groups (Table). In a univariable regression model to predict grade ≥2 IrAEs, a PLR >300 was associated with a lower incidence of clinically significant IrAEs (OR = 0.40; p=0.044). NLR >5 was associated with a trend toward lower incidence of clinically significant IrAEs (OR = 0.58; p=0.097). Multivariate analyses confirmed PLR as independent predictive marker of grade ≥2 IrAEs (OR = 0.24; p=0.007). Antibiotics use was not associated with IrAE incidence (OR = 1.02; p=0.954). Steroid use was associated with a >2-fold higher incidence of grade ≥2 IrAEs (OR = 2.74; p<0.001), though it may be noted that 37% of pts received steroids for treatment of IrAEs. Conclusions: Lower NLR & PLR may predict the appearance of IrAEs in HCC treated with ICI, although this conclusion warrants prospective validation. This finding is in keeping with several studies that showed improved survival in pts who develop of IrAEs & have a lower NLR & PLR.[Table: see text]

BACKGROUND AND AIMS:Combination atezolizumab/bevacizumab is the gold standard for first-line treatment of unresectable hepatocellular carcinoma (HCC). Our study investigated the efficacy and safety of combination therapy in older patients with HCC. METHODS:191 consecutive patients from eight centres receiving atezolizumab and bevacizumab were included. Overall survival (OS), progression-free survival (PFS), overall response rate (ORR) and disease control rate (DCR) defined by RECIST v1.1 were measured in older (age ≥ 65 years) and younger (age < 65 years) age patients. Treatment-related adverse events (trAEs) were evaluated. RESULTS:The elderly (n = 116) had higher rates of non-alcoholic fatty liver disease (19.8% vs. 2.7%; p < .001), presenting with smaller tumours (6.2 cm vs 7.9 cm, p = .02) with less portal vein thrombosis (31.9 vs. 54.7%, p = .002), with fewer patients presenting with BCLC-C stage disease (50.9 vs. 74.3%, p = .002). There was no significant difference in OS (median 14.9 vs. 15.1 months; HR 1.15, 95% CI 0.65-2.02 p = .63) and PFS (median 7.1 vs. 5.5 months; HR 1.11, 95% CI 0.54-1.92; p = .72) between older age and younger age. Older patients had similar ORR (27.6% vs. 20.0%; p = .27) and DCR (77.5% vs. 66.1%; p = .11) compared to younger patients. Atezolizumab-related (40.5% vs. 48.0%; p = .31) and bevacizumab-related (44.8% vs. 41.3%; p = .63) trAEs were comparable between groups. Rates of grade ≥3 trAEs and toxicity-related treatment discontinuation were similar between older and younger age patients. Patients 75 years and older had similar survival and safety outcomes compared to younger patients. CONCLUSIONS:Atezolizumab and bevacizumab therapy is associated with comparable efficacy and tolerability in older age patients with unresectable HCC.

Background and Aims Atezolizumab plus bevacizumab (AtezoBev) is the standard of care for first-line treatment of unresectable HCC. No evidence exists as to its use in routine clinical practice in patients with impaired liver function. Approach and Results In 216 patients with HCC who were consecutively treated with AtezoBev across 11 tertiary centers, we retrospectively evaluated treatment-related adverse events (trAEs) graded (G) according to Common Terminology Criteria for Adverse Events v5.0, including in the analysis all patients treated according to label (n = 202, 94%). We also assessed overall survival (OS), progression-free survival (PFS), overall response (ORR), and disease control rates (DCR) defined by Response Evaluation Criteria in Solid Tumors v1.1. Disease was mostly secondary to viral hepatitis, namely hepatitis C (n = 72; 36%) and hepatitis B infection (n = 35, 17%). Liver function was graded as Child-Pugh (CP)-A in 154 patients (76%) and CP-B in 48 (24%). Any grade trAEs were reported by 143 patients (71%), of which 53 (26%) were G3 and 3 (2%) G4. Compared with CP-A, patients with CP-B showed comparable rates of trAEs. Presence and grade of varices at pretreatment esophagogastroduodenoscopy did not correlate with bleeding events. After a median follow-up of 9.0 months (95% CI, 7.8-10.1), median OS was 14.9 months (95% CI, 13.6-16.3), whereas median PFS was 6.8 months (95% CI, 5.2-8.5). ORR and DCR were respectively 25% and 73%, with no difference across CP classes. Conclusions This study confirms reproducible safety and efficacy of AtezoBev in routine practice. Patients with CP-B reported similar tolerability compared with CP-A, warranting prospective evaluation of AtezoBev in this treatment-deprived population.

Peripheral blood interleukin 6, interleukin 10, and T lymphocyte levels are associated with checkpoint inhibitor induced pneumonitis: a case report

Background and Objective: Heparin-induced thrombocytopenia (HIT) can develop if immune responses to infections become pathologic in the presence of heparins. Low molecular weight heparin or unfractionated heparin are recommended for prophylaxis and treatment of venous thromboembolic disease in hospitalized patients with Covid-19 infection but may trigger HIT. Our aim is to alert clinicians that HIT occurs in association with Covid-19 infections even in the absence of prior exposure and may not be easily recognized without a high index of suspicion. Case Summary: A 33-year-old previously healthy male was initially evaluated for low grade fever, dyspnea without hypoxia and cough. A Covid-19 PCR swab was negative despite a recent exposure. He was treated with azithromycin. However, his symptoms did not improve, he then developed right leg swelling and hypoxia, so he was re-evaluated. CTA of the chest showed bilateral pulmonary emboli and ground-glass opacities at the lung bases. Venous Duplex Ultrasound showed non-occlusive thrombus in the deep veins of right lower extremity. He was hospitalized and placed on oxygen and heparin. Covid-19 swab was negative again. Laboratory tests before heparin showed a decreased platelet count of 64,000 k/ul, elevated prothrombin time of 16.4 seconds, normal aPTT at 30.8 seconds, decreased serum fibrinogen at 120 mg/dl and markedly elevated D-dimer at 59,966 ng/ml. Lupus anticoagulant and anti-phospholipid antibody tests were negative. On heparin at the desired therapeutic aPTT target range, the right leg became significantly swollen and painful by day five. Platelet count had decreased further to 39,000 k/ul. Repeat doppler examination of the right leg now showed more severe and extensive deep venous thrombosis. D-dimer had increased to 125,133 ng/ml. The HIT 4T score was 4, suggesting intermediate probability. Rapid HIT immunoassays on 2 separate samples were positive. Heparin was discontinued and he was placed on argatroban. Serotonin release assays on 2 separate samples came back positive. Suspicion for Covid-19 infection remained high and so a Covid-19 serology sample was obtained which was positive for IgG. A repeat nasopharyngeal swab at this time turned positive. He did not receive any COVID specific treatments. As viability of his leg appeared threatened, he underwent right iliofemoral vein thrombectomy with arteriovenous fistula creation. He improved on argatroban and was transitioned to apixaban with gradual normalization of hemostasis laboratory parameters, improvement in hypoxemia and fading clinical symptoms, he was discharged home on day 15. Conclusion: Current consensus guidelines for thromboprophylaxis and treatment of thromboembolism in hospitalized patients with Covid-19 infection recommend heparins as primary therapy to reduce morbidity and mortality. However, our report in addition to the two previous reports of HIT in Covid-19 patients illustrate that HIT can be a complication in the setting of Covid-19 infection. Further, our report also highlights that HIT with thrombosis can occur in a spontaneous manner in the absence of prior heparin exposure, which has been so far studied only in bacterial infection with the hypothesis that Platelet factor 4 (PF4) can bind to negatively charged polysaccharides on the surface of bacteria, triggering an immune response. Disclosures No relevant conflicts of interest to declare.

Cell-based immunotherapy is rapidly emerging as a promising alternative to conventional chemotherapy-based treatment for cancer. Previous studies have shown that high salt treatment induces naive CD4+T lymphocytes to differentiate into a highly proinflammatory Th17 phenotype. In our current study, we analyzed the ability of salt treatment to induce cancer-specific Th17 lymphocytes. Naive CD4+T cells isolated by immunomagnetic bead isolation from splenocytes of 10-week-old BALB/c mice were treated in vitro with high salt (Δ0.05 M NaCl) along with CD3 monoclonal antibodies (mAbs), CD28 mAbs and IL-2 for 4 days along with heat killed 4T1 breast cancer cells. The isolated CD4+CCR6+CD45RA-CXCR3- cells were tested for IL-17 expression by flow cytometry and determined to be >95% pure. Orthotopic murine breast tumor models established by injection of 4T1 cells into the mammary fat pad of Nu/J mice were administered two doses of (1 × 106) salt induced Th17 cells on day 7 and day 12, post-tumor implantation. By day 28, the high salt induced Th17 cells cohort demonstrated significantly reduced tumor growth (97 ± 34 mm3 vs 512 ± 91 mm3, untreated control, p Citation Format: Suneetha Amara, Pooja Yenuga, Roy Zent, Venkataswarup Tiriveedhi. NFAT5/TonEBP mediated anti-tumor efficiency of high salt activated CD4+T lymphocytes [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr B45.

Mammaglobin-A (MamA) is overexpressed in 40–80% of all human breast cancers. Recent phase I clinical trials of the MamA DNA vaccine showed encouraging safety outcomes. However, this vaccine elicited only a modest increase in MamA specific CD8+T lymphocyte (CTL) activation. As vaccine adjuvants play a critical role in enhancing the immunotherapeutic efficiency of vaccines, we tested the potential role of three synthetic CpG oligodeoxynucleotides (ODN2216—class A ODN, ODN2006—class B ODN, and ODN M362—class C ODN) to further enhance MamA specific CTL responses. Towards this, naïve CD8+T cells were obtained from healthy HLA-A2+ human donors. The HLA-A2 specific immunodominant epitope of MamA, MamA2.1 (LIYDSSLCDL), was utilized to activate naïve CD8+T cells. The THP-1 (HLA-A2+) cells were used as antigen presenting cells to stimulate naïve CD8+T cells along with (or without) co-treatment of various ODNs mentioned above. Activation of naïve CD8+T cells with the MamA2.1 peptide along with ODNs demonstrated enhanced MamA specific CTL mediated cytotoxicity on AU565 (HLA-A+/MamA+) breast cancer cells following co-treatment with ODN2006 and M362 compared to ODN2216 or MamA2.1 peptide alone. However, no significant cytotoxicity was noted upon treatment of MamA2.1 activated CTLs on MCF7 (HLA-A+/MamA−) cells, suggesting that the activation of CTLs is specific to the MamA antigen. Functional characterization studies demonstrated specific IL-12 mediated cross-talk between TLR-6 and -9 in THP-1 cells following stimulation with ODN2006 and M362, which was critical for the final cytotoxic activation of CD8+T lymphocytes. Based on these data, we conclude that ODN2006 and ODN M362 exerted a strong adjuvant effect through induction of the initial innate immune response through TLR9 upregulation followed by enhanced MamA specific CTL dependent adaptive immune responses. Our current data provide evidence for the application of Class-B/-C-CpG-ODNs as potential vaccine adjuvants towards enhancing the success of MamA based breast cancer vaccination.

Recent phase I DNA vaccine clinical trials with Mammaglobin-A (Mam-A), a human breast tumor-associated antigen (TAA), have shown to be safe and efficient. However, the success of cancer vaccines is limited by the diminished expression of HLA class I molecules on cancer cells. In our current communication, we studied the impact of various selenocompounds towards the expression of HLA class I molecules on breast cancer cells and their impact on the cytotoxicity of MamA2.1 (HLA-A2 immunodominant epitope of Mam-A) activated human CD8+T lymphocytes (hCTLs). We noted an enhanced HLA-A2 expression along with upregulation of components involved in antigen presentation machinery in all four breast cancer cell lines, namely AU565, UACC-812, MCF-7, and MDA-MB-231, following treatment with methyselenol producing methylseninic acid (MSA) and dimethylselenide (DMDSe). Furthermore, we have demonstrated enhanced cytotoxicity of MamA2.1 activated CTLs on HLA-A2+/Mam-A+ AU565 and UACC-812 cell lines following pre-treatment with MSA and DMDSe, while no significant toxicity was noted under similar conditions on HLA-A2+/Mam-A− MCF-7 and MDA-MB-231 breast cancer cell lines. Taken together, our data demonstrated that MSA and DMDSe potentiate effector cytotoxic responses following TAA vaccine specific activation of CD8+T lymphocytes, and thus suggesting their futuristic role as vaccine adjuvants in cancer immunotherapy.

Tumor initiating stem cells (TISCs) are a subset of tumor cells, which are implicated in cancer relapse and resistance to chemotherapy. The metabolic programs that drive TISC functions are exquisitely unique and finely-tuned by various oncogene-driven transcription factors to facilitate pro-cancerous adaptive challenges. While this change in TISC metabolic machinery allows for the identification of associated molecular targets with diagnostic and prognostic value, these molecules also have a potential immunological application. Recent studies have shown that these TISC-associated molecules have strong antigenic properties enabling naïve CD8+T lymphocytes to differentiate into cytotoxic effector phenotype with anticancer potential. In spite of the current challenges, a detailed understanding in this direction offers an immense immunotherapeutic opportunity. In this review, we highlight the molecular targets that characterize TISCs, the metabolic landscape of TISCs, potential antitumor immune cell activation, and the opportunities and challenges they present in the development of new cancer therapeutics.