Stat3 inhibitor abrogates the expression of PD-1 ligands on lymphoma cell lines

Combination of STAT3 inhibitor with Herceptin reduced immune checkpoints expression and provoked anti-breast cancer immunity: An in vitro study

Breast cancer (BC) is the most prevalent diagnosed cancer among women. Herceptin blocks the effects of Her-2 and tumour cell growth. Despite many achievements using Herceptin in Her-2+ invasive BC treatment, there are treatment failures and resistances. The signal transducer and activator of transcription 3 (STAT3) is persistently activated in BC and is associated with immune suppression and tumour cell proliferation. We evaluated whether STAT3 inhibition could increase Herceptin impact on in vitro reduction of immune checkpoint inhibitors and polarize T cells to a protective immune response. We treated SK-BR-3 cells with Herceptin and the STAT3-inhibitor (FLLL32) and assessed the apoptosis and expression of apoptosis-related proteins, VEGF, Her-2 and apoptosis targets of STAT3. PBMCs were isolated from healthy donors and co-cultured with SK-BR-3 cells in the presence or absence of Herceptin and FLLL32. PD-L1, CTLA-4, TIM-3 and T-cell intracellular cytokines were then evaluated. Our results demonstrated that STAT3 inhibition and Herceptin increased SK-BR-3 cell apoptosis, significantly. STAT3 inhibition through combination treatment had a more significant effect on regulating PD-1, TIM-3 and CTLA-4 expression on PBMCs. Alternatively, the combination of FLLL32 and Herceptin promoted T helper-1 protective immune response. The combination of FLLL32 and Herceptin suppress the expression of immune checkpoints and provoke the T-helper1 immune response in lymphocytes. Our analysis indicates STAT3 as a promising target that improves Herceptin's role in breast cancer cell apoptosis.

Regorafenib induces damage-associated molecular patterns, cancer cell death and immune modulatory effects in a murine triple negative breast cancer model

Damage associated molecular patterns (DAMPs), including calreticulin (CRT) exposure, high-mobility group box 1 protein (HMGB1) elevation, and ATP release, characterize immunogenic cell death (ICD) and may play a role in cancer immunotherapy. Triple negative breast cancer (TNBC) is an immunogenic subtype of breast cancer with higher lymphocyte infiltration. Here, we found that regorafenib, a multi-target angiokinase inhibitor previously known to suppress STAT3 signaling, induced DAMPs and cell death in TNBC cells. Regorafenib induced the expression of HMGB1 and CRT, and the release of ATP. Regorafenib-induced HMGB1 and CRT were attenuated following STAT3 overexpression. In a 4T1 syngeneic murine model, regorafenib treatment increased HMGB1 and CRT expression in xenografts, and effectively suppressed 4T1 tumor growth. Immunohistochemical staining revealed increased CD4⁺ and CD8⁺ tumor-infiltrating T cells in 4T1 xenografts following regorafenib treatment. Regorafenib treatment or programmed death-1 (PD-1) blockade using anti-PD-1 monoclonal antibody reduced lung metastasis of 4T1 cells in immunocompetent mice. While regorafenib increases the proportion of MHC II high expression on dendritic cells in mice with smaller tumors, the combination of regorafenib and PD-1 blockade did not show a synergistic effect on anti-tumor activity. These results suggest that regorafenib induces ICD and suppresses tumor progression in TNBC. It should be carefully evaluated when developing a combination therapy with an anti-PD-1 antibody and a STAT3 inhibitor.

Classic Hodgkin lymphoma with marked granulomatous reaction: A clinicopathologic study of 20 cases

Granulomatous reactions can be associated with various types of lymphoma, most commonly classic Hodgkin lymphoma (CHL). In some cases, the granulomatous reaction is extensive, obscuring the presence of neoplastic cells and potentially leading to delayed diagnosis and treatment. It is unknown if this subgroup of CHL has any unique clinicopathologic features. Here, we assessed the clinical and pathological features of 20 cases of CHL with a marked granulomatous reaction, defined in this study as granulomas representing ≥50% of the total cellularity/space of the specimen. This cohort of patients showed a male predominance (M:F ratio = 1.9:1) and 75% of patients were older than 40 years. Nineteen (95%) patients presented with lymphadenopathy with the neck/supraclavicular areas being most commonly involved (11/19; 58%). Advanced stage (III-IV) disease and B symptoms were present in 69% and 64% of patients, respectively. The morphologic features of these neoplasms fit best with mixed cellularity type. The Hodgkin and Reed-Sternberg (HRS) cells were positive for CD30, PAX5 (weak), pSTAT3 (80%), CD15 (70%), PD-L1 (67%), EBV-encoded small RNA (EBER)/LMP1 (50%) and CD20 (42%), and were negative for CD3, CD5, CD45, ALK and pERK. The histiocytes of the granulomas were positive for PD-L1 (67%), pSTAT3 (50%), and were negative for pERK and cyclin D1. Next generation sequencing using a 162-gene panel was negative for mutations in 4 cases. With a median follow-up of 58.9 months (range, 3.4-199.2 months), the median overall survival was 111 months and the 5-year overall survival was 78%. In summary, patients with CHL and a marked granulomatous reaction can present a diagnostic challenge and the pathologist must be alert to the possible presence of CHL to avert potential misdiagnosis. The histiocytes in the granulomas frequently express PD-L1, likely through the activation of the JAK/STAT pathway, suggesting a potential role for PD-1 blockade therapy in these patients.

Liujunzi decoction exerts potent antitumor activity in oesophageal squamous cell carcinoma by inhibiting miR-34a/STAT3/IL-6R feedback loop, and modifies antitumor immunity

BACKGROUND

Liujunzi decoction (LJZD), a traditional herbal formula and one of the most commonly used adjuvant medications for the treatment of oesophageal squamous cell carcinoma (ESCC), exerts good antitumor and immunomodulatory activity. However, its specific mechanism of action remains largely unclear.

PURPOSE

In order to examine the potential primary and adjuvant antitumor mechanisms of LJZD, both in vitro and in vivo.

METHODS

IL-6 and miR-34a inhibitors were used to activate the miR-34a/STAT3/IL-6R feedback loop to observe the effects of LJZD. A humanised mouse model with a functional human immune system was constructed to evaluate the antitumor efficacy of LJZD in vivo on xenograft tumours, which was compared to that of the positive control drug anti-PD-1 monoclonal antibodies (mAb). Finally, a co-culture system of peripheral blood mononuclear and tumour cells in vitro was used to analyse the cytotoxic activity of LJZD on T cells.

RESULTS

LJZD significantly interfered with IL-6-induced activation of the miR-34a/STAT3/IL-6R feedback loop in ESCC by restoring the expression of the tumour suppressor miR-34a, and inhibited the proliferation of EC109 oesophageal cancer cells in a dose-dependant manner. Furthermore, LJZD effectively suppressed oesophageal tumour growth in vivo and alleviated organ injury and visceral index. Furthermore, LJZD boosted antitumor immunity by increasing IFN-γ expression and CD8⁺tumour-infiltrating lymphocytes (TILs) infiltration in the peripheral blood and tumour tissues, respectively, which may be related to a decrease in PD-1, but not PD-L1 expression. Finally, we confirmed that LJZD strengthens the killing ability of T cells by suppressing PD-1 expression in a co-culture system in vitro.

CONCLUSION

LJZD exerts excellent antitumor effect by interfering with the miR-34a/STAT3/IL-6R feedback loop and augmenting antitumor immune responses. Which provides new insights into mechanisms for LJZD and sheds light on the multifaceted role of phytomedicine in cancer.

Immunosuppressive B cells expressing PD-1/PD-L1 in solid tumors: a mini review

Expression of programmed cell death-1 (PD-1/CD279) on T cells and the ligand of PD-1, programmed death ligand-1 (PD-L1) (CD274/B7-H1) on tumor cells or other immune cells, such as myeloid-derived suppressor cells, are important mechanisms to induce malignant immunosuppression. PD-1/PD-L1 expression on B-cell subsets, as well as their signaling and inhibitory functions in solid tumors will be discussed in this review with the focus on how B cells expressing PD-1/PD-L1 play immunosuppressive roles in tumor progression, aiming to figure out the potential for development of diagnostic tools and new therapies involving this unique group of cells.

PD-L1: Can it be a biomarker for the prognosis or a promising therapeutic target in cervical cancer?

Cervical cancer is one of the most common in the female genital tract and remains a leading cause that threatens the health and lives of women worldwide, although preventive vaccines and early diagnosis have reduced mortality. While treatment by operation and chemoradiotherapy for early-stage patients achieve good outcomes, the great majority of cervical cancers caused by the human papilloma virus (HPV) make immunotherapy realizable for patients with advanced and recurrent cervical cancer. To date, some clinical trials of checkpoint immunotherapy in cervical cancer have indicated significant benefits of programmed cell death-1/programmed cell death-ligand 1 (PD-1/PD-L1) inhibitors, providing strong evidence for PD-1/PD-L1 as a therapeutic target. In this review article, we discuss the role of PD-L1 and the application of PD-L1 inhibitors in cervical cancer, with the aim of providing direction for future research.

Discovery of Pyrrole-imidazole Polyamides as PD-L1 Expression Inhibitors and Their Anticancer Activity via Immune and Nonimmune Pathways

In recent years, PD-1 immune checkpoint inhibitors based on monoclonal antibodies have revolutionized cancer therapy, but there still exist unresolved issues, such as the high cost, the relatively low response rates, and so on, compared with small-molecule drugs. Herein a type of pyrrole-imidazole (Py-Im) polyamide as a small-molecule DNA binder was designed and synthesized, which could competitively bind to the same double-stranded DNA stretch in the PD-L1 promoter region as the STAT3 binding site and thus downregulate PD-L1 expression. It was demonstrated that the Py-Im polyamides directly caused apoptosis in tumor cells and retarded cell migration in the absence of T cells through inhibiting the Akt/caspase-3 pathway. Also, in a coculture system, they enhanced the T-cell-mediated killing of tumor cells by the reversal of immune escape. Because such polyamides induced antitumor effects via both immune and nonimmune pathways, they could be further developed as promising PD-L1 gene-targeting antitumor drugs.

The Roles of Programmed Cell Death Ligand-1/ Programmed Cell Death-1 (PD-L1/PD-1) in HPV-induced Cervical Cancer and Potential for their Use in Blockade Therapy

BACKGROUND

Cervical cancer induced by infection with human papillomavirus (HPV) remains a leading cause of mortality for women worldwide although preventive vaccines and early diagnosis have reduced morbidity and mortality. Advanced cervical cancer can only be treated with either chemotherapy or radiotherapy but the outcomes are poor. The median survival for advanced cervical cancer patients is only 16.8 months.

METHODS

We undertook a structural search of peer-reviewed published studies based on 1). Characteristics of programmed cell death ligand-1/programmed cell death-1(PD-L1/PD-1) expression in cervical cancer and upstream regulatory signals of PD-L1/PD-1 expression, 2). The role of the PD-L1/PD-1 axis in cervical carcinogenesis induced by HPV infection and 3). Whether the PD-L1/PD-1 axis has emerged as a potential target for cervical cancer therapies.

RESULTS

One hundred and twenty-six published papers were included in the review, demonstrating that expression of PD-L1/PD-1 is associated with HPV-caused cancer, especially with HPV 16 and 18 which account for approximately 70% of cervical cancer cases. HPV E5/E6/E7 oncogenes activate multiple signalling pathways including PI3K/AKT, MAPK, hypoxia-inducible factor 1α, STAT3/NF-kB and microRNA, which regulate PD-L1/PD-1 axis to promote HPV-induced cervical carcinogenesis. The PD-L1/PD-1 axis plays a crucial role in the immune escape of cervical cancer through inhibition of host immune response. Creating an "immune-privileged" site for initial viral infection and subsequent adaptive immune resistance, which provides a rationale for the therapeutic blockade of this axis in HPV-positive cancers. Currently, Phase I/II clinical trials evaluating the effects of PDL1/ PD-1 targeted therapies are in progress for cervical carcinoma, which provide an important opportunity for the application of anti-PD-L1/anti-PD-1 antibodies in cervical cancer treatment.

CONCLUSION

Recent research developments have led to an entirely new class of drugs using antibodies against the PD-L1/PD-1 thus promoting the body's immune system to fight cancer. The expression and roles of the PD-L1/ PD-1 axis in the progression of cervical cancer provide great potential for using PD-L1/PD-1 antibodies as a targeted cancer therapy.

miR-101, miR-548b, miR-554, and miR-1202 are reliable prognosis predictors of the miRNAs associated with cancer immunity in primary central nervous system lymphoma

MicroRNAs (miRNAs) inhibit protein function by silencing the translation of target mRNAs. However, in primary central nervous system lymphoma (PCNSL), the expression and functions of miRNAs are inadequately known. Here, we examined the expression of 847 miRNAs in 40 PCNSL patients with a microarray and investigated for the miRNA predictors associated with cancer immunity-related genes such as T helper cell type 1/2 (Th-1/Th-2) and regulatory T cell (T-reg) status, and stimulatory and inhibitory checkpoint genes, for prognosis prediction in PCNSL. The aim of this study is to find promising prognosis markers based on the miRNA expression in PCNSL. We detected 334 miRNAs related to 66 cancer immunity-related genes in the microarray profiling. Variable importance measured by the random survival forest analysis and Cox proportional hazards regression model elucidated that 11 miRNAs successfully constitute the survival formulae dividing the Kaplan-Meier curve of the respective PCNSL subgroups. On the other hand, univariate analysis shortlisted 23 miRNAs for overall survival times, with four miRNAs clearly dividing the survival curves-miR-101/548b/554/1202. These miRNAs regulated Th-1/Th-2 status, T-reg cell status, and immune checkpoints. The miRNAs were also associated with gene ontology terms as Ras/MAP-kinase, ubiquitin ligase, PRC2 and acetylation, CDK, and phosphorylation, and several diseases including acquired immunodeficiency syndrome, glioma, and those related to blood and hippocampus with statistical significance. In conclusion, the results demonstrated that the four miRNAs comprising miR-101/548b/554/1202 associated with cancer immunity can be a useful prognostic marker in PCNSL and would help us understand target pathways for PCNSL treatments.

Prognostic value and clinicopathological characteristics of PD-L1 overexpression in non-Hodgkin lymphoma: a meta-analysis

BACKGROUND

Programmed cell death ligand 1 (PD-L1) has already been detected in various carcinomas. In non-Hodgkin lymphoma (NHL), however, the prognostic value of PD-L1 overexpression remains unclear.

METHODS

A meta-analysis of 2321 NHL patients from 12 studies was performed. Hazard ratios (HRs) with 95% confidence intervals (CIs) were used to evaluate the correlation between PD-L1 overexpression and prognosis of NHL, and odds ratios (ORs) with 95% CIs were used to assess the association of PD-L1 overexpression with clinicopathological factors.

RESULTS

The results showed that no significant difference between PD-L1 positive and negative groups was detected in NHL (HR: 1.40, 95% CI: 0.90-2.19; P = 0.137). Nevertheless, the results indicated that PD-L1 overexpression was associated with poor prognosis in the subtype of diffuse large B cell lymphoma (DLBCL) (HR: 1.70, 95% CI: 1.05-2.74; P = 0.031). We also performed subgroup analyses and meta-regression. The pooled OR showed that PD-L1 overexpression was associated with B symptoms, higher international prognostic index (IPI) score (3, 4, and 5 points) and Ann Arbor Stages III and IV.

CONCLUSIONS

The meta-analysis demonstrated that PD-L1 expression was not associated with prognosis of NHL but was associated with prognosis of DLBCL.

Differential expression of individual transcript variants of PD-1 and PD-L2 genes on Th-1/Th-2 status is guaranteed for prognosis prediction in PCNSL

In current molecular medicine, next-generation sequencing (NGS) for transcript variant detection and multivariable analyses are valid methods for evaluating gene expression, cancer mechanisms, and prognoses of patients. We conducted RNA-sequencing on samples from patients with primary central nervous system lymphoma (PCNSL) using NGS and performed multivariable analysis on gene expression data and correlations focused on Th-1/Th-2 helper T cell balance and immune checkpoint to identify diagnosis/prognosis markers and cancer immune pathways in PCNSL. We selected 84 transcript variants to limit the analysis range for Th-1/Th-2 balance and stimulatory and inhibitory checkpoints in 31 PCNSLs. Of these, 21 highly-expressed transcript variants were composed of the formulas for prognoses based on Th-1/Th-2 status and checkpoint activities. Using formulas, Th-1^low, Th-2^high, and stimulatory checkpoint^high resulted in poor prognoses. Further, Th-1^highTh-2^low was associated with good prognoses. On the other hand, CD40-001^high and CD70-001^high as stimulatory genes, and LAG3-001^high, PDCD1 (PD-1)-001/002/003^high, and PDCD1LG2 (PD-L2)-201^low as inhibitory genes were associated with poor prognoses. Interestingly, Th-1^highTh-2^low and Th-1^lowTh-2^high were correlated with stimulatory checkpoint^low as CD70-001^low and inhibitory checkpoint^low as HAVCR2 (TIM-3)-001^low and PDCD1LG2-001/201^low, respectively. Focused on the inhibitory checkpoint, specific variants of CD274 (PD-L1)-001 and PDCD1-002 served severe hazard ratios. In particular, PDCD1-002^high by a cut off score was associated with poor prognoses, in addition to PDCD1-001/003^high, PDCD1LG2-201^low, and LAG3-001^high. These results mainly suggest that expression of transcript variants of PDCD1 and PDCD1LG2 on the Th-1/Th-2 balance enable prognostic prediction in PCNSL. This study provides insights for development of molecular target therapies and identification of diagnosis/prognosis markers in PCNSL.

Systemic, primary cutaneous, and breast implant-associated ALK-negative anaplastic large-cell lymphomas present similar biologic features despite distinct clinical behavior

Despite distinct clinical presentation and outcome, systemic, primary cutaneous, and breast implant-associated anaplastic large cell lymphomas (S-, PC-, BI-ALCL) ALK-negative (ALK-) show similar histopathological features including the presence of the "hallmark" cells with horseshoe-shaped nuclei and CD30 protein expression. The purpose was to better characterize these three entities using immunohistochemistry and FISH (Fluorescent in situ hybridization) to identify biomarkers differently expressed and that might be involved in their pathogenesis. Twenty-two S-ALCL ALK-, 13 PC-ALCL, and 2 BI-ALCL were included. Cases were tested for P53, P63, MUM1, MYC, GATA3, p-STAT3, PD1, and PDL1 protein expression and DUP22, TP53, TP63, MYC, and PDL1 chromosomal aberrations. As expected, S-ALCL ALK- patients had adverse outcome compare to PC and BI-ALCL. No difference was observed between the three groups concerning protein expression except for MUM1 that was significantly more frequently expressed in S-ALCL ALK- compared to PC-ALCL. In particular, constitutive activation of the STAT3 pathway and PDL1/PD1 immune-checkpoint expression was present in the three entities. TP53 deletion and PDL1 gene amplification were the commonest cytogenetic alterations and were present in the three entities. None of the studied biological parameters was associated with prognosis. Despite distinct clinical behavior, S-ALCL ALK-, PC-ALCL, and BI-ALCL share similar biological features. Larger series should be investigated with the current approach to determine more precisely the activity and the prognostic value of these biomarkers and pathways in each group.

Potential anti-lymphoma effect of M-CSFR inhibitor in adult T-cell leukemia/lymphoma

The c-fms proto-oncogene is also known as macrophage colony stimulating factor receptor (M-CSFR) or colony-stimulating factor-1 receptor (CSF-1R), and is expressed on several types of malignant tumor cells and myeloid cells. In the present study, we found that overexpression of M-CSFR was present in adult T-cell leukemia/lymphoma (ATLL) cases. M-CSFR signaling was associated with lymphoma cell proliferation, and M-CSFR inhibition induced apoptosis in lymphoma cells. The ATLL cell line ATL-T expressed M-CSF/CSF-1 and interleukin (IL)-34, which are both M-CSFR ligands. M-CSF and IL-34 expression was seen in ATLL cases, and co-expression of these ligands was detected in 11 of 13 ATLL cases. M-CSFR inhibition suppressed programmed death-1 and -2 ligand in ATL-T cells and macrophages stimulated with conditioned medium from ATL-T cells. Thus, an M-CSFR inhibitor may be useful as additional therapy against ATLL due to direct and indirect mechanisms.

Clinicopathologic implication of PD-L1 and phosphorylated STAT3 expression in diffuse large B cell lymphoma

BACKGROUND

Antitumor immune response of programmed cell death ligand (PD-L1) has shown clinical value not only in Hodgkin lymphoma and EBV-associated lymphomas but also in EBV-negative diffuse large B cell lymphoma (DLBCL) of non-germinal center B cell-like (non-GCB) subtype. Signal transducer and activator of transcription 3 (STAT3) is known to induce PD-L1 in immune cells and its activated form, phosphorylated STAT3 (pSTAT3), is also frequently expressed in non-GCB DLBCL. Herein, we investigated associations between PD-L1 expression/gene alteration, pSTAT3 expression and clinicopathologic variables in EBV-negative DLBCL.

METHODS

In 107 cases of DLBCLs with non-GCB subtype (67%; 72/107), GCB subtype (25%; 27/107) and unclassifiable cases (8%; 8/107), we performed PD-L1 and pSTAT3 immunohistochemistry and fluorescence in situ hybridization for PD-L1 gene translocation and copy number gain/amplification.

RESULTS

PD-L1 was expressed in tumor cells (PD-L1t) in 21% (23/107; 30% cutoff), immune cells (PD-L1i) in 36% (38/107; 20% cutoff), and pSTAT3 in tumor nuclei in 41% (44/107; 40% cutoff). PD-L1 gene alteration was observed in 10% (10/102) including translocation in 6% (6/102) and copy number gain/amplification in 4% (4/102). Non-GCB subtype was associated with PD-L1t and pSTAT3 (p = 0.006 and p = 0.042), and tended to have PD-L1 gene alteration (p = 0.058). Tumoral PD-L1 expression without gene alteration (PD-L1t+ GA-) correlated with pSTAT3-positive tumor cell proportions (%) (p = 0.033). In survival analysis, pSTAT3 expression independently predicted shorter PFS in total cohort (p = 0.017) and R-CHOP-treated group (p = 0.007), and in pSTAT3-negative R-CHOP-treated subset, PD-L1 expression in immune cells (PD-L1i) correlated with shorter PFS (p = 0.042).

CONCLUSIONS

Gene alteration and protein expression of PD-L1 and pSTAT3 expression were closely related in DLBCL and constituted features of non-GCB subtype. In addition to known clinical significance of pSTAT3, immune cell expression of PD-L1 (PD-L1i) had also clinical value in pSTAT3-dependent manner. These findings may provide an insight into immunotherapeutic strategy and risk stratification in DLBCL patients.

Current Immunotherapeutic Approaches in T Cell Non-Hodgkin Lymphomas

T cell non-Hodgkin lymphoma (T-NHL) is a rare and heterogeneous group of neoplasms of the lymphoid system. With the exception of a few relatively indolent entities, T-NHL is typically aggressive, treatment resistant, and associated with poor prognosis. Relatively few options with proven clinical benefit are available for patients with relapsed or refractory disease. Immunotherapy has emerged as a promising treatment for the management of patients with hematological malignancies. The identification of tumor antigens has provided a large number of potential targets. Therefore, several monoclonal antibodies (alemtuzumab, SGN-30, brentuximab vedotin, and mogamulizumab), directed against tumor antigens, have been investigated in different subtypes of T-NHL. In addition to targeting antigens involved in cancer cell physiology, antibodies can stimulate immune effector functions or counteract immunosuppressive mechanisms. Chimeric antigen receptor (CAR)-T cells directed against CD30 and immune checkpoint inhibitors are currently being investigated in clinical trials. In this review, we summarize the currently available clinical evidence for immunotherapy in T-NHL, focusing on the results of clinical trials using first generation monoclonal antibodies, new immunotherapeutic agents, immune checkpoint inhibitors, and CAR-T cell therapies.

B-cell receptor-mediated NFATc1 activation induces IL-10/STAT3/PD-L1 signaling in diffuse large B-cell lymphoma

Knowledge of programmed death ligand 1 (PD-L1) expression and its regulation in B-cell lymphoma cells is limited. Investigating mechanisms that control PD-L1 expression in B-cell lymphoma cells might identify biomarkers that predict the efficacy of immunotherapy with anti-programmed death-1/PD-L1 antibodies. In addition, identification of mechanisms that regulate PD-L1 may identify molecules that can be targeted to improve the clinical efficacy of immune checkpoint inhibitors. In this study, we used proteomic approaches and patient-derived B-cell lymphoma cell lines to investigate mechanisms that regulate PD-L1 expression. We found that PD-L1 expression, particularly in nongerminal center B cell-derived diffuse large B-cell lymphoma (DLBCL), is controlled and regulated by several interactive signaling pathways, including the B-cell receptor (BCR) and JAK2/STAT3 signaling pathways. We found that that BCR-mediated NFATc1 activation upregulates IL-10 chemokine expression in PD-L1⁺ B-cell lymphoma cells. Released IL-10 activates the JAK2/STAT3 pathway, leading to STAT3-induced PD-L1 expression. IL-10 antagonist antibody abrogates IL-10/STAT3 signaling and PD-L1 protein expression. We also found that BCR pathway inhibition by BTK inhibitors (ibrutinib, acalabrutinib, and BGB-3111) blocks NFATc1 and STAT3 activation, thereby inhibiting IL-10 and PD-L1 expression. Finally, we validated the PD-L1 signaling network in 2 primary DLBCL cohorts consisting of 428 and 350 cases and showed significant correlations among IL-10, STAT3, and PD-L1. Thus, our findings reveal a complex signaling network regulating PD-L1 expression in B-cell lymphoma cells and suggest that PD-L1 expression can be modulated by small molecule inhibitors to potentiate immunotherapies.

Au-CGKRK Nanoconjugates for Combating Cancer through T-Cell-Driven Therapeutic RNA Interference

Numerous prior studies on fighting cancer have been based on using inhibitors of JAK-STAT pathway (signal transducer and activator of transcription 3 (STAT3) inhibitor in particular), a signaling pathway responsible for progression of many types of cancer cells. However, recent studies have shown that STAT3 activation leads to upregulation of program death receptor-ligand 1 (PD-L1, an immune checkpoint protein that plays a major role behind evasion of immune systems by growing tumors) expression levels in tumor cells, leading to enhanced immune suppression. This is why global efforts are being witnessed in combating cancer through use of immune checkpoint inhibitors. Herein, we report on the design, synthesis, physicochemical characterizations, and bioactivity evaluation of novel tumor- and tumor-vasculature-targeting noncytotoxic Au-CGKRK nanoconjugates (17-80 nm) for combating tumor. Using a syngeneic mouse tumor model, we show that intraperitoneal (i.p.) administration of the Au-CGKRK nanoparticles (NPs) complexed with both PD-L1siRNA (the immune checkpoint inhibitor) and STAT3siRNA (the JAK-STAT pathway inhibitor) results in significant (>70%) enhancement in overall survivability (OS) in melanoma-bearing mice (n = 5) when compared to the OS in the untreated mice group. The expression levels of CD8 and CD4 proteins in the tumor lysates of differently treated mice groups (by Western blotting) are consistent with the observed OS enhancement being a T-cell-driven process. Biodistribution study using near-infrared dye-loaded Au-CGKRK nanoconjugates revealed selective accumulation of the dye in mouse tumor. Notably, the overall survival benefits were significantly less (∼35%) when melanoma-bearing mice were treated (i.p.) with Au-CGKRK NPs complexed with only PD-L1siRNA or with STAT3siRNA alone. The presently described Au-CGKRK nanoconjugates are expected to find future use in therapeutic RNA-interference-based cancer immunotherapy.

Genome-wide siRNA screening in mouse bone marrow-derived macrophages revealed that knockdown of ribosomal proteins suppresses IL-10 and enhances TNF-α production

Macrophages play a central role in the immune response, and their diverse functions are attributed to the spectrum of their functional states. To elucidate molecules involved in modulating the balance between the anti-inflammatory cytokine IL-10 and the pro-inflammatory cytokine TNF-α, we conducted genome-wide siRNA screening. First, we established an siRNA screening system using mouse bone marrow-derived macrophages, which are a suitable model for studying functional states of macrophages in vitro. In the primary screen and the subsequent reproducibility assay, 112 siRNA pools demonstrated enhancement of IL-10 production and 497 siRNA pools suppressed IL-10 production. After a deconvolution assay for IL-10-up-regulating siRNA pools, 8 genes were identified as IL-10 repressors, including Cnot1 and Rc3h1, components of the CCR4-NOT complex known to degrade cytokine mRNAs. On the other hand, siRNA pools targeting ribosomal proteins were frequently found among those that down-regulated IL-10 production and up-regulated TNF-α production. Four pools were assayed using deconvoluted siRNAs and identified as high-confidence hits. Thus, we found that the genome-wide knockdown of 19 ribosomal proteins resulted in decreased IL-10 and increased TNF-α production.

STAT3 as a potential immunotherapy biomarker in oncogene-addicted non-small cell lung cancer

Immune checkpoint blockade has modified the treatment landscape for many types of tumors, including lung cancer. Still our knowledge on the biology of the interaction between tumor cells and the microenvironment is limited, preventing the optimal use of these new compounds and the maximum benefit that the patients can derive from them. We have actively worked on the role of STAT3, a transcriptional factor that causes innate resistance to targeted therapies in oncogene-addicted tumors. In this short review we take the opportunity to express our opinion and review existing knowledge on the immune role of STAT3 and the possible implications that this may have for the discovery of new biomarkers to predict response to immunotherapy, as well as new partners to combine with and increase the efficacy of immune checkpoint inhibitors.

Modulating PD-L1 expression in multiple myeloma: an alternative strategy to target the PD-1/PD-L1 pathway

Even with recent advances in therapy regimen, multiple myeloma patients commonly develop drug resistance and relapse. The relevance of targeting the PD-1/PD-L1 axis has been demonstrated in pre-clinical models. Monotherapy with PD-1 inhibitors produced disappointing results, but combinations with other drugs used in the treatment of multiple myeloma seemed promising, and clinical trials are ongoing. However, there have recently been concerns about the safety of PD-1 and PD-L1 inhibitors combined with immunomodulators in the treatment of multiple myeloma, and several trials have been suspended. There is therefore a need for alternative combinations of drugs or different approaches to target this pathway. Protein expression of PD-L1 on cancer cells, including in multiple myeloma, has been associated with intrinsic aggressive features independent of immune evasion mechanisms, thereby providing a rationale for the adoption of new strategies directly targeting PD-L1 protein expression. Drugs modulating the transcriptional and post-transcriptional regulation of PD-L1 could represent new therapeutic strategies for the treatment of multiple myeloma, help potentiate the action of other drugs or be combined to PD-1/PD-L1 inhibitors in order to avoid the potentially problematic combination with immunomodulators. This review will focus on the pathophysiology of PD-L1 expression in multiple myeloma and drugs that have been shown to modulate this expression.

The MYC oncogene is a global regulator of the immune response

The MYC proto-oncogene is a gene product that coordinates the transcriptional regulation of a multitude of genes that are essential to cellular programs required for normal as well as neoplastic cellular growth and proliferation, including cell cycle, self-renewal, survival, cell growth, metabolism, protein and ribosomal biogenesis, and differentiation. Here, we propose that MYC regulates these programs in a manner that is coordinated with a global influence on the host immune response. MYC had been presumed to contribute to tumorigenesis through tumor cell-intrinsic influences. More recently, MYC expression in tumor cells has been shown to regulate the tumor microenvironment through effects on both innate and adaptive immune effector cells and immune regulatory cytokines. Then, MYC was shown to regulate the expression of the immune checkpoint gene products CD47 and programmed death-ligand 1. Similarly, other oncogenes, which are known to modulate MYC, have been shown to regulate immune checkpoints. Hence, MYC may generally prevent highly proliferative cells from eliciting an immune response. MYC-driven neoplastic cells have coopted this mechanism to bypass immune detection. Thus, MYC inactivation can restore the immune response against a tumor. MYC-induced tumors may be particularly sensitive to immuno-oncology therapeutic interventions.