Dynamic Changes in PD-L1 Expression and Immune Infiltrates Early During Treatment Predict Response to PD-1 Blockade in Melanoma

Immunotherapy for hepatocellular carcinoma: recent advances and future perspectives

The introduction of immunotherapies has been a major development in the treatment of many advanced cancers, including hepatocellular carcinoma (HCC). We are entering a new era of systemic therapy for advanced HCC associated with an explosion of clinical trial activity. Data from phase I/II studies of checkpoint inhibitors in advanced HCC have been promising, with durable objective response rates of approximately 20% seen (in both first- and second-line settings) and acceptable safety profiles (including immune-mediated hepatitis). Phase III studies evaluating anti-programmed cell death protein 1 (anti-PD-1) and anti-programmed cell death ligand 1 (anti-PD-L1) antibodies compared with sorafenib are already underway. The potential synergistic effects of anti-PD-1/anti-PD-L1 when used in combination with agents against other checkpoint molecules, systemic therapies, as well as conventional surgical and locoregional therapies are also being explored in upcoming clinical trials. Aside from this, other strategies to harness the immune system, including chimeric antigen receptor-engineered T cells, natural killer cell therapies, and peptide vaccines directed against HCC antigens have entered phase I/II studies. Current limitations of immunotherapies and areas of future research include the accurate assessment and prediction of tumor response, overcoming the immunosuppressive effects of a hypoxic microenvironment, and the management of immune-related hepatitis in patients who already have limited liver reserve.

Immunotherapy for skin cancer

Among all tumor types, skin cancers are profoundly sensitive to immunotherapy. Indeed, the recently reported response rates for anti-PD-1 (anti-programmed-death 1) therapy for cutaneous malignant melanomas (MM), Merkel cell carcinomas, basal cell carcinomas, cutaneous squamous cell carcinomas and Kaposi sarcomas are all above 40%. This unique immunogenicity renders skin cancers as a paradigm for tumor-immune interactions and is driven by high mutational burdens, over-expressed tumor antigens and/or viral antigens. However, despite the clear demonstration of immunologic cure of skin cancer in some patients, most tumors develop either early (primary) or late (adaptive) resistance to immunotherapy. Resistance mechanisms are complex, and include contributions of tumor cell-intrinsic, T cell and microenvironment factors that have been recently further elucidated with the advent of single-cell technologies. This review will focus on the exciting progress with immunotherapy for skin cancers to date, and also our current understanding of the mechanisms of resistance to immunotherapy.

A prospective observational study to assess PD-L1 expression in small biopsy samples for non-small-cell lung cancer

Background

Programmed cell death-1 (PD-1) immune checkpoint inhibitor antibody has proven to be effective in advanced non-small cell lung cancer (NSCLC) patients positive for programmed cell death-1 ligand-1 (PD-L1). However, there are currently no prospective studies evaluating PD-L1 expression for small biopsy samples.

Methods

To prospectively investigate the reliability of small samples for NSCLC, we included patients who underwent diagnostic biopsy by flexible bronchoscopy, computed tomography (CT) and ultra-sonography (US) guided core-needle to determine the PD-L1 expression status. In pathologically confirmed NSCLC, PD-L1 expression was evaluated using companion diagnostic PD-L1 immunohistochemistry. We evaluated: 1) tumor cell count and sample size, 2) tumor proportion score (TPS): <1, 1–49%, 50%≦, and 3) the concordance rate of TPS by biopsy and surgical samples.

Results

Of the 153 cases of PD-L1 expression, 110 were assessed using endobronchial ultrasonography guided transbronchial biopsy (EBUS-TBB) (thin bronchoscopy 84 cases; normal bronchoscopy 26 cases), 23 were endobronchial ultrasonography guided transbronchial needle aspiration (EBUS-TBNA), and 20 cases of CT or US-guided core-needle biopsy. Tumor cell count and sample size were significantly larger for normal bronchoscopy than thin bronchoscopy or EBUS-TBNA samples. Moreover, tumor cell counts for each subsequent biopsy decreased. In all cases, TPS distribution (undiagnosed, <1%, 1–49, 50%≦) was 2.6, 34.6, 31.4, 31.4%, respectively. TPS positive cases using thin bronchoscope was 55.9%, normal bronchoscope was 73.1% and EBUS-TBNA was 78.3%. In early stage adenocarcinoma, TPS was lower compared with advanced stages. Conversely, in squamous cell carcinoma, the rates of TPS were similar regardless of stage. The concordance rate of TPS by biopsy and surgical materials was 86.7%.

Conclusion

Utilizing smaller samples for evaluation, the frequency of TPS was comparable to past clinical trials using larger samples. The differences in TPS were influenced by diagnostic tools, cancer histologic types and staging. The concordance of TPS between EBUS-TBB samples and surgical materials was high.

Trial registration

This study was performed at the Department of Respiratory Medicine at St. Marianna University School of Medicine Hospital, with ethics approval (#3590) and registered as a clinical trial (UMIN000027030).

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5773-3) contains supplementary material, which is available to authorized users.

Combined BRAF and MEK inhibition with PD-1 blockade immunotherapy in BRAF-mutant melanoma

Oncogene-targeted therapy with B-Raf proto-oncogene (BRAF) and mitogen-activated protein kinase kinase (MEK) inhibitors induces a high initial response rate in patients with BRAF^V600-mutated melanoma, with a median duration of response of approximately 1 year^1-3. Immunotherapy with antibodies to programmed death 1 (PD-1) produces lower response rates but with long response duration. Preclinical models suggest that combining BRAF and MEK inhibitors with PD-1 blockade therapy improves antitumor activity^4-6, which may provide additional treatment options for patients unlikely to have long-lasting responses to either mode of therapy alone. We enrolled 15 patients with BRAF^V600-mutated metastatic melanoma in a first-in-human clinical trial of dabrafenib, trametinib and pembrolizumab ( NCT02130466 ). Eleven patients (73%) experienced grade 3/4 treatment-related adverse events, the most common being elevation of liver function tests and pyrexia, most of which resolved with drug interruption or discontinuation of either the anti-PD-1 antibody or the targeted therapy combination. Eleven patients (73%; 95% confidence interval = 45-92%) had an objective response, and six (40%; 95% confidence interval = 16-68%) continued with a response at a median follow-up of 27 months (range = 10.3-38.4+ months) for all patients. This study suggests that this triple-combined therapy may benefit a subset of patients with BRAF^V600-mutated metastatic melanoma by increasing the frequency of long-lasting antitumor responses.

Radiologic features of pneumonitis associated with nivolumab in non-small-cell lung cancer and malignant melanoma

Aim: To assess the clinical features/imaging characteristics of pneumonitis reported during nationwide nivolumab postmarketing surveillance in Japan. Patients & methods: Clinical and radiological data were collected from pneumonitis cases reported during/after nivolumab treatment for melanoma or non-small-cell lung cancer. The expert central review committee evaluated each case. Results: Among 144 cases analyzed, 91 (63.2%) had radiological patterns considered typical for drug-induced pneumonitis and 53 (36.8%) patients had previously unobserved patterns with one or more atypical features, including 23 cases (16.0%) with ground glass opacity confined to the area around the tumor (peritumoral infiltration). A higher proportion of patients with (vs without) peritumoral infiltration had an antitumor response to nivolumab. Conclusion: Images of nivolumab-induced pneumonitis showed previously unobserved radiological patterns.

Oncolytic virus immunotherapy induces immunogenic cell death and overcomes STING deficiency in melanoma

Successful immunotherapy for melanoma depends on the recruitment of effector CD8⁺ T cells to the tumor microenvironment. Factors contributing to T cell regulation in melanoma have recently been recognized, including the stimulator of interferon genes (STING). Agents that can activate STING or enhance T cell infiltration into established tumors have become an important focus for further clinical development. Talimogene laherparepvec (T-VEC) is an oncolytic herpes simplex virus, type 1 (HSV-1) encoding granulocyte-macrophage colony stimulating factor (GM-CSF) and is approved for the treatment of melanoma and has shown therapeutic activity in murine tumors known to express high levels of STING. The mechanism of action for T-VEC has not been fully elucidated but is thought to include induction of immunogenic cell death (ICD) and activation of host anti-tumor immunity. Thus, we sought to investigate how T-VEC mediates anti-tumor activity in a melanoma model. To determine if T-VEC induced ICD we established the relative sensitivity of a panel of melanoma cell lines to T-VEC oncolysis. Following T-VEC infection in vitro, melanoma cell lines released of HMGB1, ATP, and translocated ecto-calreticulin. To identify potential mediators of this effect, we found that melanoma cell sensitivity to T-VEC was inversely related to STING expression. CRISPR/Cas9-STING knockout was also associated with increased T-VEC cell killing. In the D4M3A melanoma, which has low expression of STING and is resistant to PD-1 blockade therapy, T-VEC was able to induce therapeutic responses in both injected and non-injected tumors and demonstrated recruitment of viral- and tumor-antigen specific CD8⁺ T cells, and induction of a pro-inflammatory gene signature at both injected and non-injected tumors. These data suggest that T-VEC induces ICD in-vitro and promotes tumor immunity and can induce therapeutic responses in anti-PD-1-refractory, low STING expressing melanoma.

Extracellular Vesicle-Based Therapeutic Targeting of β-Catenin to Modulate Anticancer Immune Responses in Hepatocellular Cancer

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide. Although HCC can respond to immune checkpoint inhibitors, such as monoclonal antibodies against programmed death 1 (PD-1), many patients fail to respond or develop secondary resistance. Activation of Wnt/β-catenin signaling can contribute to immune evasion. Mutations in β-catenin are among the most frequent mutations associated with HCC. Thus, our aim was to directly target β-catenin to enhance the therapeutic response to immune checkpoint inhibition. A synthetic transgenic mouse model of experimental HCC induced by tyrosine-protein kinase Met/β-catenin expression and extracellular vesicles (EVs) as a therapeutic delivery agent was used to evaluate the efficacy of directly targeting β-catenin on the response to anti-PD-1. These studies showed that (1) oncogenic β-catenin could be therapeutically targeted using a biological nanoparticle-based delivery approach, (2) targeting β-catenin using small interfering RNA (siRNA) delivered within EVs can reduce tumor growth, and (3) the therapeutic response to anti-PD-1 can be enhanced by concomitantly targeting β-catenin using therapeutic EVs. These preclinical studies establish the efficacy of the use of biological nanoparticles as an endogenous delivery vehicle for therapeutic RNA delivery and support the use of therapeutic strategies targeting tumor-intrinsic β-catenin as an adjunct to anti-PD-1-based therapy. Conclusion: Combination therapy with anti-PD-1 and β-catenin siRNA delivered using biological nanoparticles provides an effective strategy for the treatment of HCC. This strategy could be further exploited into targeted approaches for immune potentiation by countering oncogene-mediated resistance to immunotherapies.

Efficacy and safety of programmed cell death-1/programmed cell death ligand-1 inhibitors in advanced urothelial malignancy: A systematic review and meta-analysis

INTRODUCTION

Programmed cell death-1/programmed cell death ligand-1 (PD-1/PDL-1) inhibitors are the newest class of approved drugs for advanced urothelial cancer (AdUC). This review aims to collate the evidence for their efficacy and safety in various treatment settings.

METHODS

Extensive search of databases was performed (updated May 2018) and the protocol was registered on PROSPERO (CRD42017081568). The review was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analysis statement. STATA (v 12) and Revman 5.3.5 were used for data analysis.

RESULTS

Ten nonrandomized, open-label clinical trials were included in this review. PD-1/PD-L1 inhibitors were used as second-line, stand-alone in eight trials and as first-line in cisplatin-ineligible in two trials. Heterogeneity was observed for study design, PDL-1 testing methods, cutoff criterias used and translational markers evaluated. The pooled objective response rate (ORR) was 18.2% (95% confidence interval [CI] 15.1-21.2, n = 1785) with PD-1/PDL-1 inhibitors in second-line settings as compared to 12.6% (95% CI 10.3-14.9, n = 736) with second-line chemotherapy and 23.7% (95% CI 19.9-27.4, n = 489) with PD-1/PDL-1 inhibitors as first-line therapy in cisplatin-ineligible patients. The median progression-free survival and overall survival was similar with PD-1/PD-L1 inhibitors in both second- and first-line treatment settings (1.5-2.9 vs. 2.0-2.7 months and 7.9-18.2 vs. 15.9 months) and second-line chemotherapy (3.3-4.0 months and 7.4-8 months). Odds of achieving ORR was 0.10 (95% CI 0.03-0.31, n = 229) in the second-line, stand-alone setting with a combined positive score (CPS) cutoff of 25% and was 0.34 (95% CI 0.19-0.62, n = 265) with a CPS cut-off of 10% in first-line setting in the cisplatin-ineligible.

CONCLUSIONS

PD-1/PDL-1 inhibitors appear to be promising in the treatment of AdUC and CPS may be a potentially reliable biomarker for predicting response but needs validation. Caution needs to be exercised until more data are available on imAEs and further studies are required to prove their worth as the standard of care.

Major pathologic response on biopsy (MPRbx) in patients with advanced melanoma treated with anti-PD-1: evidence for an early, on-therapy biomarker of response

BACKGROUND

With increasing anti-PD-1 therapy use in patients with melanoma and other tumor types, there is interest in developing early on-treatment biomarkers that correlate with long-term patient outcome. An understanding of the pathologic features of immune-mediated tumor regression is key in this endeavor.

MATERIALS AND METHODS

Histologic features of immune-related pathologic response (irPR) following anti-PD-1 therapy were identified on hematoxylin and eosin (H&E)-stained slides in a discovery cohort of pre- and on-treatment specimens from n = 16 patients with advanced melanoma. These features were used to generate an irPR score [from 0 = no irPR features to 3 = major pathologic response on biopsy (MPRbx, ≤10% residual viable tumor)]. This scoring system was then tested for an association with objective response by RECIST1.1 and overall survival in a prospectively collected validation cohort of pre- and on-treatment biopsies (n = 51 on-treatment at 4-week timepoint) from melanoma patients enrolled on the nivolumab monotherapy arm of CA209-038 (NCT01621490).

RESULTS

Specimens from responders in the discovery cohort had features of immune-activation (moderate-high TIL densities, plasma cells) and wound-healing/tissue repair (neovascularization, proliferative fibrosis) compared to nonresponders, (P ≤ 0.021, for each feature). In the validation cohort, increasing irPR score associated with objective response (P = 0.009) and MPRbx associated with increased overall survival (n = 51; HR 0.13; 95%CI, 0.054-0.31, P = 0.015). Neither tumoral necrosis nor pretreatment histologic features were associated with response. Eight of 16 (50%) of patients with stable disease showed irPR features, two of which were MPRbx, indicating a disconnect between pathologic and radiographic features at the 4-week on-therapy timepoint for some patients.

CONCLUSIONS

Features of immune-mediated tumor regression on routine H&E-stained biopsy slides from patients with advanced melanoma correlate with objective response to anti-PD-1 and overall survival. An on-therapy biopsy may be particularly clinically useful for informing treatment decisions in patients with radiographic stable disease. This approach is inexpensive, straightforward, and widely available.

Immunomagnetic isolation of circulating melanoma cells and detection of PD-L1 status

Personalised medicine targeted to specific biomarkers such as BRAF and c-Kit has radically improved the success of melanoma therapy. More recently, further advances have been made using therapies targeting the immune response. In particular, therapies targeting the PD-1/PD-L1 or CTLA-4 axes alone or in combination have shown more sustained responses in 30–60% of patients. However, these therapies are associated with considerable toxicities and useful biomarkers to predict responders and non-responders are slow to emerge. Here we developed a reliable melanoma circulating tumor cell (CTC) detection method with PD-L1 evaluation on CTCs. A set of melanoma cell surface markers was tested as candidates for targeted melanoma CTC isolation and a melanoma specific immunostaining-based CTC identification protocol combined with PD-L1 detection was established. In vitro testing of the effect of exposure to blood cells on melanoma cell PD-L1 expression was undertaken. Immunomagnetic targeting isolated melanoma CTCs in up to 87.5% of stage IV melanoma patient blood samples and 3 8.6% of these had some PD-L1 expressing CTCs. Our in vitro data demonstrate PD-L1 induction on melanoma cells in the blood.This study established a robust, reliable method to isolate melanoma CTCs and detect expression of PD-L1 on these cells.

Immunotherapy in extensive small cell lung cancer

Small cell lung cancer which constitutes about 15% of lung cancers is pathobiologically and clinically distinct from non small cell cancer. Histologically it is characterized by small cells with scant cytoplasm, absent or inconspicuous nucleoli, extensive necrosis, and expresses neuroendocrine markers. It is on a spectrum of neuroendocrine cancer that extend from typical carcinoids to large cell to small cell cancer. Clinically it behaves in a more malignant fashion with a rapid doubling time, early metastasis. They respond rapidly to cytotoxic treatment however tend to develop resistance soon. Immunotherapy with checkpoint inhibitors take advantage of PD 1 ligand-receptor axis between the tumor and T cells or CTLA4 on T cells which when engaged lead to inhibition of T cells. This inhibition helps tumors to evade immune surveillance. Checkpoint inhibitors break this axis by either binding to PD 1 ligands or PD 1 to CTLA4, thereby preventing tumors to evade the immune systems. This has led to remarkable responses in tumors. The immune related adverse effects can be severe however are experienced at much lower rates as compared to cytotoxic chemotherapy. Recently, CheckMate 032 has shown impressive response rates with Nivolumab and Nivolumab/Ipilimumab in relapsed small cell cancer. IMpower 133, a phase 3 trial showed that addition of Atezolizumab to Carbo/Etoposide led to a significant survival benefit in treatment naive extensive small cell cancer. This review will summarize recent developments and ongoing studies of immune therapy in extensive small cell cancer in addition to a brief summary of immune therapy landscape of Non small cell lung cancer. Investigational approaches to immune therapy have also been delineated.

Enhancing antitumor response by combining immune checkpoint inhibitors with chemotherapy in solid tumors

BACKGROUND

Cancer immunotherapy has changed the standard of care for a subgroup of patients with advanced disease. Immune checkpoint blockade (ICB) in particular has shown improved survival compared with previous standards of care for several tumor types. Although proven to be successful in more immunogenic tumors, ICB is still largely ineffective in patients with tumors that are not infiltrated by immune cells, the so-called cold tumors.

PATIENTS AND METHODS

This review describes the effects of different chemotherapeutic agents on the immune system and the potential value of these different types of chemotherapy as combination partners with ICB in patients with solid tumors. Both preclinical data and currently ongoing clinical trials were evaluated. In addition, we reviewed findings regarding different dosing schedules, including the effects of an induction phase and applying metronomic doses of chemotherapy.

RESULTS

Combining ICB with other treatment modalities may lead to improved immunological conditions in the tumor microenvironment and could thereby enhance the antitumor immune response, even in tumor types that are so far unresponsive to ICB monotherapy. Chemotherapy, that was originally thought to be solely immunosuppressive, can exert immunomodulatory effects which may be beneficial in combination with immunotherapy. Each chemotherapeutic drug impacts the tumor microenvironment differently, and in order to determine the most suitable combination partners for ICB it is crucial to understand these mechanisms.

CONCLUSION

Preclinical studies demonstrate that the majority of chemotherapeutic drugs has been shown to exert immunostimulatory effects, either by inhibiting immunosuppressive cells and/or activating effector cells, or by increasing immunogenicity and increasing T-cell infiltration. However, for certain chemotherapeutic agents timing, dose and sequence of administration of chemotherapeutic agents and ICB is important. Further studies should focus on determining the optimal drug combinations, sequence effects and optimal concentration-time profiles in representative preclinical models.

Immunotherapy for genitourinary tumors

The present review provides an update about the major achievements and recent advances of immunotherapy in renal cell carcinoma, urothelial carcinoma, and prostate cancer. Although the treatment strategy for renal cell carcinoma and urothelial carcinoma includes traditional cancer immunotherapies, such as interleukin-2 and interferon-alfa, the clinical outcomes of these therapies are unsatisfactory. In recent years, the development of immune checkpoint inhibitors has drastically changed the treatment strategy for various cancers, including genitourinary cancer. The present review summarizes the approved cancer immunotherapies for renal cell carcinoma, urothelial carcinoma and prostate cancer. Furthermore, we review the response evaluation and biomarkers for immune checkpoint inhibitors with a distinctive mode of action that is different from cytotoxic agents. Finally, future perspectives for cancer immunotherapy are discussed.

Durable intracranial and extracranial response to nivolumab with appearance of secondary resistance in a heavily pretreated patient with head and neck cancer

BACKGROUND

Recently, nivolumab was approved in the second-line setting of squamous cell cancer of the head and neck (SCCHN). The benefits of PD-(L)1 inhibitors in PD-L1(-) tumors are unclear, and no reports exist on the activity of these agents in brain metastases from SCCHN. Little is known regarding the mechanisms underlying acquired resistance to PD-(L)1 inhibition.

METHODS

A patient with PD-L1(-) metastatic SCCHN progressing to cetuximab-based chemotherapy received third-line nivolumab. T cell infiltration and mRNA expression of immune-related genes were compared in prenivolumab and postnivolumab biopsies from a progressing tumor lesion.

RESULTS

An exceptional local and systemic response was achieved, including complete devitalization of brain metastases that lasted for more than a year. Increased T cell infiltration and upregulation of genes related to T cell exhaustion and resistance to PD-1 inhibition were found.

CONCLUSION

Durable responses to PD-(L)1 inhibitors may be observed in biomarker-negative SCCHN. Mechanisms of resistance should be studied.

The Emerging Role of Surgery for Patients With Advanced Melanoma Treated With Immunotherapy

BACKGROUND

The emergence of immune checkpoint inhibitors (ICIs) has improved survival for patients with metastatic melanoma. The types of disease-response patterns to ICI therapy can be more complex relative to traditional chemotherapy and include mixed responses, pseudoprogression, and oligoprogression. The potential benefit of surgery after incomplete response to ICI therapy has not been explored. The purpose of this study was to explore outcomes of surgery after ICI therapy in patients with metastatic melanoma.

METHODS

A retrospective study was conducted at two centers and included patients with melanoma who underwent surgery after treatment with monotherapy or combination therapy with anti-programmed cell death protein (PD) 1 and/or anti-cytotoxic T-lymphocyte associated protein (CTLA)-4 checkpoint blockade.

RESULTS

Of 25 patients, nine received anti-CTLA-4 therapy, eight received anti-PD-1 therapy, and eight received both anti-CTLA-4 and anti-PD-1 therapies before surgery. Five patients were treated in the adjuvant setting and developed new lesions, whereas 20 patients were treated for metastatic disease and underwent surgery for persistent disease on imaging after ICI therapy. Twenty-five patients underwent 30 operations without complications. Twenty-seven of 30 masses were confirmed to be melanoma on pathology, one was a desmoid tumor and two were necrosis. At a median follow-up of 14.2 months, 2 patients died, 8 were alive with a known disease, and 15 continued to have no further evidence of disease.

CONCLUSIONS

Surgery was well tolerated in this cohort of patients receiving ICI therapy for melanoma. Surgery may benefit select patients with an oligoprogressive disease after ICI therapy. After a mixed response, surgery remains the only definitive method to render some patients free of disease.

Reasoning the effect of immunotherapy after chemoradiation in the PACIFIC trial

Durvalumab consolidation after chemoradiation has been a giant leap in the treatment of stage III non-small-cell lung cancer with an unprecedented 16.8-month median progression-free survival. PACIFIC trial is a new foray into chemoimmunotherapy trials where we apply our knowledge of 'immunogenic cell death' and 'Abscopal' effect of radiation in the clinic. Our understanding of immunotherapy after chemoradiation treatment and application of immunogenic cell death biomarkers in future trials may be the approach we need to maximize benefit of these treatments in the appropriate patients.

T Cell-Inflamed versus Non-T Cell-Inflamed Tumors: A Conceptual Framework for Cancer Immunotherapy Drug Development and Combination Therapy Selection

Immunotherapies such as checkpoint-blocking antibodies and adoptive cell transfer are emerging as treatments for a growing number of cancers. Despite clinical activity of immunotherapies across a range of cancer types, the majority of patients fail to respond to these treatments and resistance mechanisms remain incompletely defined. Responses to immunotherapy preferentially occur in tumors with a preexisting antitumor T-cell response that can most robustly be measured via expression of dendritic cell and CD8+ T cell-associated genes. The tumor subset with high expression of this signature has been described as the T cell-"inflamed" phenotype. Segregating tumors by expression of the inflamed signature may help predict immunotherapy responsiveness. Understanding mechanisms of resistance in both the T cell-inflamed and noninflamed subsets of tumors will be critical in overcoming treatment failure and expanding the proportion of patients responding to current immunotherapies. To maximize the impact of immunotherapy drug development, pretreatment stratification of targets associated with either the T cell-inflamed or noninflamed tumor microenvironment should be employed. Similarly, biomarkers predictive of responsiveness to specific immunomodulatory therapies should guide therapy selection in a growing landscape of treatment options. Combination strategies may ultimately require converting non-T cell-inflamed tumors into T cell-inflamed tumors as a means to sensitize tumors to therapies dependent on T-cell killing. Cancer Immunol Res; 6(9); 990-1000. ©2018 AACR.

Biomarkers for predicting efficacy of PD-1/PD-L1 inhibitors

Programmed cell death protein 1/programmed cell death ligand 1 (PD-1/PD-L1) is a negative modulatory signaling pathway for activation of T cell. It is acknowledged that PD-1/PD-L1 axis plays a crucial role in the progression of tumor by altering status of immune surveillance. As one of the most promising immune therapy strategies, PD-1/PD-L1 inhibitor is a breakthrough for the therapy of some refractory tumors. However, response rate of PD-1/PD-L1 inhibitors in overall patients is unsatisfactory, which limits the application in clinical practice. Therefore, biomarkers which could effectively predict the efficacy of PD-1/PD-L1 inhibitors are crucial for patient selection. Biomarkers reflecting tumor immune microenvironment and tumor cell intrinsic features, such as PD-L1 expression, density of tumor infiltrating lymphocyte (TIL), tumor mutational burden, and mismatch-repair (MMR) deficiency, have been noticed to associate with treatment effect of anti-PD-1/anti-PD-L1 therapy. Furthermore, gut microbiota, circulating biomarkers, and patient previous history have been found as valuable predictors as well. Therefore establishing a comprehensive assessment framework involving multiple biomarkers would be meaningful to interrogate tumor immune landscape and select sensitive patients.

Drug response to PD-1/PD-L1 blockade: based on biomarkers

In recent years, immunotherapies targeting programmed death-1 (PD-1)/programmed death ligand 1 (PD-L1) have provided great hopes for patients with cancer. A successful anti-PD-1/PD-L1 therapy includes not only the elimination of immunosuppressive tumor cells but also the rejuvenation of exhausted T cells. Nevertheless, the efficacy of therapy is still low, so that biomarker-driven therapy has attracted more and more attention to identify patients who are likely to benefit from therapy and to reduce unnecessary disease progression. While many studies have focused on characteristics of tumor biopsies, biomarkers linked to T cell exhaustion and rejuvenation have just become new hot spots in drug response studies. However, no biomarker is perfect in drug response prediction currently, so there is an urgent need for other biomarkers to compensate for the deficiency. In this review, we summarize some approved and candidate biomarkers predictive of drug response before and during PD-1/PD-L1 blockade, including those characterizing responsive or suppressive tumor cells and those evaluating the T cell rejuvenation. Overall, we set up a comprehensive network of biomarkers of tumor characteristics and T cell rejuvenation, predicting drug response before and during anti-PD-1/PD-L1 therapies.

Biomarkers for Immune Checkpoint Inhibitors in Melanoma

Immune checkpoint inhibitors have now become a standard therapy for malignant melanoma. However, as immunotherapies are effective in only a limited number of patients, biomarker development remains one of the most important clinical challenges. Biomarkers predicting clinical benefit facilitate appropriate selection of individualized treatments for patients and maximize clinical benefits. Many biomarkers derived from tumors and peripheral blood components have recently been reported, mainly in retrospective settings. This review summarizes the recent findings of biomarker studies for predicting the clinical benefits of immunotherapies in melanoma patients. Taking into account the complex interactions between the immune system and various cancers, it would be difficult for only one biomarker to predict clinical benefits in all patients. Many efforts to discover candidate biomarkers are currently ongoing. In the future, verification, by means of a prospective study, may allow some of these candidates to be combined into a scoring system based on bioinformatics technology.

Immune cell profiling in the age of immune checkpoint inhibitors: implications for biomarker discovery and understanding of resistance mechanisms

Immunotherapy has changed the landscape of cancer treatment. The introduction of immune checkpoint inhibitors has seen tremendous success in improving overall survival of patients with advanced metastatic cancers and has now become the standard of care for multiple tumor types. However, efficacy of immune checkpoint blockade appears to be limited to immunogenic cancers, and even amongst immune-reactive cancers, response rates are low and variable between patients. Recent data have also demonstrated the rapid emergence of resistance to immune checkpoint inhibitors, with some patients progressing on treatment within one year. Significant research efforts are now directed at identifying predictive biomarkers and mechanisms of resistance to immune checkpoint blockade. These studies are underpinned by comprehensive and detailed profiling of the immune milieu. In this review, we discuss the utility and efficacy of immune cell profiling to uncover biomarkers of response and mechanisms of resistance to immune checkpoint inhibitors.

An update on the Society for Immunotherapy of Cancer consensus statement on tumor immunotherapy for the treatment of cutaneous melanoma: version 2.0

BACKGROUND

Cancer immunotherapy has been firmly established as a standard of care for patients with advanced and metastatic melanoma. Therapeutic outcomes in clinical trials have resulted in the approval of 11 new drugs and/or combination regimens for patients with melanoma. However, prospective data to support evidence-based clinical decisions with respect to the optimal schedule and sequencing of immunotherapy and targeted agents, how best to manage emerging toxicities and when to stop treatment are not yet available.

METHODS

To address this knowledge gap, the Society for Immunotherapy of Cancer (SITC) Melanoma Task Force developed a process for consensus recommendations for physicians treating patients with melanoma integrating evidence-based data, where available, with best expert consensus opinion. The initial consensus statement was published in 2013, and version 2.0 of this report is an update based on a recent meeting of the Task Force and extensive subsequent discussions on new agents, contemporary peer-reviewed literature and emerging clinical data. The Academy of Medicine (formerly Institute of Medicine) clinical practice guidelines were used as a basis for consensus development with an updated literature search for important studies published between 1992 and 2017 and supplemented, as appropriate, by recommendations from Task Force participants.

RESULTS

The Task Force considered patients with stage II-IV melanoma and here provide consensus recommendations for how they would incorporate the many immunotherapy options into clinical pathways for patients with cutaneous melanoma.

CONCLUSION

These clinical guidleines provide physicians and healthcare providers with consensus recommendations for managing melanoma patients electing treatment with tumor immunotherapy.

Specific expression of PD-L1 in RELA-fusion supratentorial ependymoma: Implications for PD-1-targeted therapy

BACKGROUND

A desperate need for novel therapies in pediatric ependymoma (EPN) exists, as chemotherapy remains ineffective and radiotherapy often fails. EPN have significant infiltration of immune cells, which correlates with outcome. Immune checkpoint inhibitors provide an avenue for new treatments. This study characterizes tumor-infiltrating immune cells in EPN and aims at predicting candidates for clinical trials using checkpoint inhibitors targeting PD-L1/PD-1 (programmed death ligand 1/programmed death 1).

METHODS

The transcriptomic profiles of the primary study cohort of EPN and other pediatric brain tumors were interrogated to identify PD-L1 expression levels. Transcriptomic findings were validated using the western blotting, immunohistochemistry and flow cytometry.

RESULTS

We evaluated PD-L1 mRNA expression across four intracranial subtypes of EPN in two independent cohorts and found supratentorial RELA fusion (ST-RELA) tumors to have significantly higher levels. There was a correlation between high gene expression and protein PD-L1 levels in ST-RELA tumors by both the western blot and immunohistochemisty. The investigation of EPN cell populations revealed PD-L1 was expressed on both tumor and myeloid cells in ST-RELA. Other subtypes had little PD-L1 in either tumor or myeloid cell compartments. Lastly, we measured PD-1 levels on tumor-infiltrating T cells and found ST-RELA tumors express PD-1 in both CD4 and CD8 T cells. A functional T-cell exhaustion assay found ST-RELA T cells to be exhausted and unable to secrete IFNγ on stimulation.

CONCLUSIONS

These findings in ST-RELA suggest tumor evasion and immunsuppression due to PD-L1/PD-1-mediated T-cell exhaustion. Trials of checkpoint inhibitors in EPN should be enriched for ST-RELA tumors.

Deviations of the immune cell landscape between healthy liver and hepatocellular carcinoma

Tumor-infiltrating immune cells are highly relevant for prognosis and identification of immunotherapy targets in hepatocellular carcinoma (HCC). The recently developed CIBERSORT method allows immune cell profiling by deconvolution of gene expression microarray data. By applying CIBERSORT, we assessed the relative proportions of immune cells in 41 healthy human livers, 305 HCC samples and 82 HCC adjacent tissues. The obtained immune cell profiles provided enumeration and activation status of 22 immune cell subtypes. Mast cells were evaluated by immunohistochemistry in ten HCC patients. Activated mast cells, monocytes and plasma cells were decreased in HCC, while resting mast cells, total and naïve B cells, CD4+ memory resting and CD8+ T cells were increased when compared to healthy livers. Previously described S1, S2 and S3 molecular HCC subclasses demonstrated increased M1-polarized macrophages in the S3 subclass with good prognosis. Strong total immune cell infiltration into HCC correlated with total B cells, memory B cells, T follicular helper cells and M1 macrophages, whereas weak infiltration was linked to resting NK cells, neutrophils and resting mast cells. Immunohistochemical analysis of patient samples confirmed the reduced frequency of mast cells in human HCC tumor tissue as compared to tumor adjacent tissue. Our data demonstrate that deconvolution of gene expression data by CIBERSORT provides valuable information about immune cell composition of HCC patients.

Emerging Biomarkers in Cutaneous Melanoma

Earlier identification of aggressive melanoma remains a goal in the field of melanoma research. With new targeted and immune therapies that have revolutionized the care of patients with melanoma, the ability to predict progression and monitor or predict response to therapy has become the new focus of research into biomarkers in melanoma. In this review, promising biomarkers are highlighted. These biomarkers have been used to diagnose melanoma as well as predict progression to advanced disease and response to therapy. The biomarkers take various forms, including protein expression at the level of tissue, genetic mutations of cancer cells, and detection of circulating DNA. First, a brief description is provided about the conventional tissue markers used to stage melanoma, including tumor depth. Next, protein biomarkers, which provide both diagnostic and prognostic information, are described. This is followed by a discussion of important genetic mutations, microRNA, and epigenetic modifications that can provide therapeutic and prognostic material. Finally, emerging serologic biomarkers are reviewed, including circulating melanoma cells and exosomes. Overall the goal is to identify biomarkers that aid in the earlier identification and improved treatment of aggressive melanoma.

RANKL blockade improves efficacy of PD1-PD-L1 blockade or dual PD1-PD-L1 and CTLA4 blockade in mouse models of cancer

Receptor activator of NF-κB ligand (RANKL) and its receptor RANK, are members of the tumor necrosis factor and receptor superfamilies, respectively. Antibodies targeting RANKL have recently been evaluated in combination with anti-CTLA4 in case reports of human melanoma and mouse models of cancer. However, the efficacy of anti-RANKL in combination with antibodies targeting other immune checkpoint receptors such as PD1 has not been reported. In this study, we demonstrated that blockade of RANKL improves anti-metastatic activity of antibodies targeting PD1/PD-L1 and improves subcutaneous growth suppression in mouse models of melanoma, prostate and colon cancer. Suppression of experimental lung metastasis following combination anti-RANKL with anti-PD1 requires NK cells and IFN-γ, whereas subcutaneous tumor growth suppression with this combination therapy is attenuated in the absence of T cells and IFN-γ. Furthermore, addition of anti-RANKL to anti-PD1 and anti-CTLA4 resulted in superior anti-tumor responses, irrespective of the ability of anti-CTLA4 isotype to engage activating FcR, and concurrent or delayed RANKL blockade was most effective. Early-during-treatment assessment reveals this triple combination therapy compared to dual anti-PD1 and anti-CTLA4 combination therapy further increased the proportion of tumor-infiltrating CD4⁺ and CD8⁺ T cells that can produce both IFN-γ and TNF. Finally, RANKL expression appears to identify tumor-specific CD8⁺ T cells expressing higher levels of PD1 which can be modulated by anti-PD1. These data set the scene for clinical evaluation of denosumab use in patients receiving contemporary immune checkpoint blockade.

Tumor-Associated Macrophages: Therapeutic Targets for Skin Cancer

Tumor-associated macrophages (TAMs) and regulatory T cells (Tregs) are significant components of the microenvironment of solid tumors in the majority of cancers. TAMs sequentially develop from monocytes into functional macrophages. In each differentiation stage, TAMs obtain various immunosuppressive functions to maintain the tumor microenvironment (e.g., expression of immune checkpoint molecules, production of Treg-related chemokines and cytokines, production of arginase I). Although the main population of TAMs is immunosuppressive M2 macrophages, TAMs can be modulated into M1-type macrophages in each differential stage, leading to the suppression of tumor growth. Because the administration of certain drugs or stromal factors can stimulate TAMs to produce specific chemokines, leading to the recruitment of various tumor-infiltrating lymphocytes, TAMs can serve as targets for cancer immunotherapy. In this review, we discuss the differentiation, activation, and immunosuppressive function of TAMs, as well as their benefits in cancer immunotherapy.

Triple negative breast cancer - prognostic role of immune-related factors: a systematic review

PURPOSE

Treatment of breast cancer has been increasingly successful in recent years with the advent of HER2-receptor targeted treatment and endocrine treatment. However, the triple negative subgroup of breast cancer (TNBC) (estrogen-, progesterone- and HER2-receptor negative) still lacks targeted treatment options. TNBC is a type of breast cancer that often affects younger women, and generally has a worse prognosis than other types of breast cancer. Recently, the complex role of the immune system in cancer growth, elimination and metastasis has been the object of increased attention. There is hope that a more detailed understanding of the intricate roles of the constituents of the immune system, will hold potential both as prognostic or predictive markers of cancer progression, but also as treatment targets for a wide range of tumors, including TNBC. The aim of this review is to provide an overview of the cellular immune microenvironment in TNBC, and to highlight areas in which TNBC may differ from other types of breast cancer.

MATERIAL AND METHODS

A search of PubMed was made using the terms 'triple negative breast cancer' and 'tumor infiltrating lymphocytes', 'CD8', 'CD4', 'B cells', 'natural killer cells', 'macrophages', myeloid derived suppressor cells', 'dendritic cells', 'immune check point inhibitor', 'CTLA-4' and 'PD-L1'.

RESULTS

We find that whilst factors such as TILs and certain subgroups of TILs (e.g., CD8 + and regulator T-cells) have been extensively researched, none of these markers are currently applicable to routine clinical practice. Also, TNBC differs from other types of breast cancer with regards to cellular composition of the immune infiltrate and PD-L1 expression, and the prognostic significance of these.

CONCLUSIONS

Immune-related factors have the potential as both prognostic and predictive biomarkers for new treatments targeting the immune system in breast cancer. However, multivariate analyses, taking other well-known factors into account, are required to determine the true value of these biomarkers. Also, differences between TNBC and other types of breast cancer may have implications for treatment and use of immune-related factors as biomarkers.

Microbial biomarkers for immune checkpoint blockade therapy against cancer

Three major standard treatments, i.e., surgery, chemotherapy, and radiotherapy, were traditionally applied to the treatment of cancer and saved many patients. Meanwhile, clinical studies as well as basic research of immunotherapy are being actively conducted for intractable or advanced malignancies that cannot be cured by the conventional standard treatments. Remarkable therapeutic efficacies have been recently reported in clinical trials on some cancer types, and immunotherapy is now being recognized as the "fourth" standard therapy against cancer. In particular, immune checkpoint inhibitor therapy (ICI) has demonstrated the effectiveness of immunotherapy through large-scale randomized clinical trials, leading to the paradigm-shift in cancer treatment. Immune checkpoint molecules transduce co-inhibitory signals to immunocompetent cells including T cells, and crucially contribute to the formation of an immunosuppressive microenvironment in tumor tissues, which intrinsically confers the treatment resistance. Programmed death-1 (PD-1, CD279) is one of the typical immune checkpoint molecules. Anti-tumor therapies targeting PD-1 and its ligands had been developed and approved in many countries, and various studies utilizing clinical specimens are currently progressing. In this review, we provide an overview of the biomarkers based on the analysis of enteric microbiota that correlate with the clinical efficacy/inefficacy of PD-1-based therapy.

PD-L1 status does not predict the outcome of BRAF inhibitor therapy in metastatic melanoma

BACKGROUND

Targeted therapies with BRAF plus MEK inhibitors (BRAFi; MEKi) represent the major treatment strategy for patients with BRAF-mutated metastatic melanoma (MM). Previous analyses suggested a correlation between programmed death-ligand 1 (PD-L1) expression in tumour tissues and the outcome of targeted therapies. This study investigated PD-L1 as a potential predictive biomarker of BRAFi-based targeted therapies in MM patients.

PATIENTS AND METHODS

We analysed two independent cohorts of BRAF V600-mutated MM patients undergoing BRAFi-based therapies for PD-L1 expression in pre-treatment tumour tissues. The oligocentre cohort 1 included 83 patients whose tumour tissues were analysed retrospectively with the anti-PD-L1 antibody clone E1L3N. The multicentre cohort 2 included 58 patients whose tumour tissues were analysed prospectively within the framework of the "Registry of the Arbeitsgemeinschaft Dermatologische Onkologie" (ADOREG) and "Tissue Registry in Melanoma" (TRIM) project using the anti-PD-L1 antibody clone 28-8.

RESULTS

PD-L1 expression in pre-treatment tumour tissue did not correlate with response or survival to BRAFi-based therapies in both MM patient cohorts. This finding was not influenced by retrospective versus prospective immunohistochemistry analyses, oligocentre versus multicentre cohorts or the different anti-PD-L1 antibody clones used. In cohort 1, PD-L1 positivity was detected in tumour tissue of 41.0% and 18.1% of patients (cut-off 1% and 5%, respectively). In cohort 2, 58.6% and 39.7% of patients showed PD-L1 positivity (cut-off 1% and 5%, respectively).

CONCLUSION

In two independent cohorts including a total of 141 MM patients, PD-L1 expression in tumour tissue did not correlate with the outcome of BRAFi-based treatment. Therefore, PD-L1 cannot be recommended for the use as a predictive biomarker of BRAFi-based therapy in BRAF V600-mutated MM.

PD-1 blockade reverses adaptive immune resistance induced by high-dose hypofractionated but not low-dose daily fractionated radiation

Preclinical evidence suggests that high-dose hypofractionated ionizing radiation (IR) can enhance anti-tumor immunity and result in significant tumor control when combined with immune checkpoint blockade (ICB). However, low-dose daily fractioned IR used for many tumor types including head and neck squamous cell carcinoma results in lymphopenia and may be immunosuppressive. We compared immune correlates, primary tumor and abscopal tumor control rates following the addition of PD-1 mAb to either high-dose hypofractioned (8Gyx2) or low-dose daily fractionated (2Gyx10) IR in syngeneic models of cancer. When compared to 2Gyx10 IR, 8Gyx2 IR preserved peripheral and tumor-infiltrating CD8+ T-lymphocyte accumulation and activation and reduced peripheral and tumor gMDSC accumulation. Regulatory T-lymphocytes were largely unaltered. Type I and I IFN levels and expression of IFN-responsive MHC class I and PD-L1 was enhanced in tumors treated with 8Gyx2 compared to 2Gyx10 IR. Functionally, tumor-specific CD8+ T-lymphocyte IFN responses within tumor draining lymph nodes were enhanced following 8Gyx2 IR but suppressed following 2Gyx10 IR. When combined with PD-1 mAb, reversal of adaptive immune resistance and subsequent enhancement of CD8+ cell dependent primary and abscopal tumor control was observed following 8Gyx2 but not 2Gyx10 IR. These data strongly support that compared to daily fractionated low-dose IR, high-dose hypofractionated IR preserves or enhances anti-tumor immunity and, when combined with PD-1 mAb to reverse adaptive immune resistance, promotes anti-tumor immunity to control primary and distant tumors. These data critically inform the rational design of trials combining IR and ICB.

Progress and challenges of predictive biomarkers of anti PD-1/PD-L1 immunotherapy: A systematic review

Despite the marked success of applications of PD-1/PD-L1 checkpoint blockades in clinical, the efficacy and responsiveness of these agents varies greatly among different tumor types and across individual patients. Therefore, establishment of predictive biomarkers for checkpoint blockades is of the most importance to maximize the therapeutic benefits. In this review, we discuss the current progress and challenges of developing predictive biomarkers of immunotherapy responsiveness, aiming to provide some directions for future studies. PD-L1 expression is a logical biomarker for the prediction of response to anti-PD-(L)1 immunotherapies. However, the predictive values of PD-L1 expressions for immunotherapy are currently debating and challenging. Multiplex detecting methods and combined biomarkers may provide new strategies. For example, tumor mutation and neoantigens burden, some oncogene mutations, like EGFR, ALK, KRAS and STK11. In addition, with development of new probes and tracers, immuno-PET provide a new, non-invasive and quantitative strategy to monitor treatment response. As current evidence of those potential predictors, a consensus and standardization is needed to establish to widely applied in future studies. Multiplex detecting methods and combined biomarkers may provide new strategies.

Primary and Acquired Resistance to Immune Checkpoint Inhibitors in Metastatic Melanoma

Immune checkpoint inhibitors have revolutionized the treatment of patients with advanced-stage metastatic melanoma, as well as patients with many other solid cancers, yielding long-lasting responses and improved survival. However, a subset of patients who initially respond to immunotherapy, later relapse and develop therapy resistance (termed "acquired resistance"), whereas others do not respond at all (termed "primary resistance"). Primary and acquired resistance are key clinical barriers to further improving outcomes of patients with metastatic melanoma, and the known mechanisms underlying each involves various components of the cancer immune cycle, and interactions between multiple signaling molecules and pathways. Due to this complexity, current knowledge on resistance mechanisms is still incomplete. Overcoming therapy resistance requires a thorough understanding of the mechanisms underlying immune evasion by tumors. In this review, we explore the mechanisms of primary and acquired resistance to immunotherapy in melanoma and detail potential therapeutic strategies to prevent and overcome them. Clin Cancer Res; 24(6); 1260-70. ©2017 AACR.

Targeting myeloid cells in the tumor sustaining microenvironment

Myeloid cells are the most abundant cells in the tumor microenvironment (TME). The tumor recruits and modulates endogenous myeloid cells to tumor-associated macrophages (TAM), dendritic cells (DC), myeloid-derived suppressor cells (MDSC) and neutrophils (TAN), to sustain an immunosuppressive environment. Pathologically overexpressed mediators produced by cancer cells like granulocyte-macrophage colony-stimulating- and vascular endothelial growth factor induce myelopoiesis in the bone marrow. Excess of myeloid cells in the blood, periphery and tumor has been associated with tumor burden. In cancer, myeloid cells are kept at an immature state of differentiation to be diverted to an immunosuppressive phenotype. Here, we review human myeloid cells in the TME and the mechanisms for sustaining the hallmarks of cancer. Simultaneously, we provide an introduction into current and novel therapeutic approaches to redirect myeloid cells from a cancer promoting to a rather inflammatory, cancer inhibiting phenotype. In addition, the role of platelets for tumor promotion is discussed.