Differential Activity of Nivolumab, Pembrolizumab and MPDL3280A according to the Tumor Expression of Programmed Death-Ligand-1 (PD-L1): Sensitivity Analysis of Trials in Melanoma, Lung and Genitourinary Cancers

Response assessment of bone metastatic disease: seeing the forest for the trees RECIST, PERCIST, iRECIST, and PCWG-2

Tumor response is often used as a surrogate marker for survival practically in all clinical trials. Therefore, robust and valid response criteria during the course of trials are fundamental for the assessment of response to therapy. This aspect, however, becomes particularly challenging when it comes to bone metastases. In the era of targeted therapies and immune-checkpoint inhibitors (ICI), response assessment by morphologic-based criteria cannot detect the real tumor response and, consequently, fail to demonstrate the actual clinical benefit. This review will focus on some of the most common morphologic and metabolic response criteria and their application for bone lesions, highlighting relative strengths and weaknesses as well as potential future methods in the era of target therapies and immunotherapy with ICI.

PD-L1 for selecting non-small-cell lung cancer patients for first-line immuno-chemotherapy combination: a systematic review and meta-analysis

Aim: With the final aim to explore the first-line treatment options for non-small-cell lung cancer (NSCLC) patients, we performed a systematic review and literature-based meta-analysis of available clinical trials exploring immunotherapy in combination versus standard histology-based chemotherapy. Materials & methods: We evaluated interactions according to type of treatment-add-on strategy: immunotherapy in combination versus standard chemotherapy-based regimens. Hazard ratio (HR) for overall survival (OS) and progression-free survival (PFS) were extracted and cumulated. Results: Seven trials (4278 patients) were included. The addition of immunotherapy to standard chemotherapy-based regimens significantly increased OS (HR 0.74; p = 0.001) and PFS (HR 0.61; p < 0.0001) compared with standard-of-care in NSCLC patients in first-line setting. Conclusion: Immunotherapy-based regimens constantly improved OS and PFS compared with chemotherapy in first-line treatment of nononcogene-addicted NSCLC.

Urothelial cancer: a narrative review of the role of novel immunotherapeutic agents with particular reference to the management of non-muscle-invasive disease

AIM

This narrative review describes current guidelines for treating NMIBC, provides an overview of the principle behind immune checkpoint inhibition, and summarizes current evidence for checkpoint inhibitors in urothelial malignancy. Further, we discuss potential strategies for immune checkpoint inhibition in the management of NMIBC.

BACKGROUND

Adjuvant intravesical BCG immunotherapy has been the mainstay of treatment for high-risk non-muscle-invasive bladder cancer (NMIBC) for decades but is associated with both a significant side effect profile and failure rate. Recently, a substantial body of trial data has been published demonstrating the successful use of systemic immunotherapy in the treatment of advanced urothelial malignancy and, in particular, a class of drugs known as 'immune checkpoint inhibitors'. This has led to the approval of a number of these drugs by the UK National Institute of Health and Care Excellence and the US Food and Drug Administration, and ongoing trials are examining use in the management of NMIBC.

METHODS

To identify relevant published data, using the PubMed/ Medline search engine, an online search of the Pubmed/ Medline archives was conducted using the terms bladder cancer' in combination with 'checkpoint inhibitors', and limited to articles in English published between 1966 and September 2017.To identify ongoing trials of interest but not yet published, a further search of the clinical trials.gov search engine was conducted using the term 'non-muscle-invasive bladder cancer'.

CONCLUSION

There has been little advance in available adjuvant therapy for NMIBC treated with TURBT. Current intravesical therapies are associated with a high recurrence rate and significant side effect profile. The impending publication of the wealth of ongoing trials, both into the delivery and efficacy of checkpoint inhibition will direct the future treatment of NMIBC.

Tumor suppression of novel anti-PD-1 antibodies mediated through CD28 costimulatory pathway

Novel anti–PD-1 antibodies (Abs) not blocking the PD-1–PDL-1 interaction are presented with equivalent antagonistic activity to classical blocking anti–PD-1 Abs and have distinct mechanisms of action that synergize in functional recovery of exhausted CD8 T cells and enhancing tumor suppression in an immunogenic mouse tumor model.

Classical antagonistic antibodies (Abs) targeting PD-1, such as pembrolizumab and nivolumab, act through blockade of the PD-1–PDL-1 interaction. Here, we have identified novel antagonistic anti–PD-1 Abs not blocking the PD-1–PDL-1 interaction. The nonblocking Abs recognize epitopes on PD-1 located on the opposing face of the PDL-1 interaction and overlap with a newly identified evolutionarily conserved patch. These nonblocking Abs act predominantly through the CD28 coreceptor. Importantly, a combination of blocking and nonblocking Abs synergize in the functional recovery of antigen-specific exhausted CD8 T cells. Interestingly, nonblocking anti–PD-1 Abs have equivalent antitumor activity compared with blocker Abs in two mouse tumor models, and combination therapy using both classes of Abs enhanced tumor suppression in the mouse immunogenic tumor model. The identification of the novel nonblocker anti–PD-1 Abs and their synergy with classical blocker Abs may be instrumental in potentiating immunotherapy strategies and antitumor activity.

Sustained partial remission of a metastatic NEN using off-label immunotherapy with pembrolizumab

Neuroendocrine neoplasms (NEN) are a heterogeneous group of tumors, which can be histologically separated by primary location, proliferation rate and differentiation of tumor cells. The therapeutic options and outcome depend on grading, staging and resectability of the tumor. Established treatment options of neuroendocrine tumors (NET) and carcinomas (NEC) are based especially on surgery, tumor specific medical treatments, peptide guided radioreceptor therapy (PRRT) and locoregional therapies. We report about a patient diagnosed with a pancreatic, non-functional NET/NEC G2/3 with a proliferation rate of 20% at initial immunohistochemical diagnosis. During the course of the disease, the proliferation rate increased up to more than 50% over a period of 5 years. Due to loss of response to established therapies (i.e. systemic chemotherapy, targeted therapy and brachytherapy), an off-label immunotherapy with the PD-1 antibody pembrolizumab was initiated based on a 30% PD-L1 expression in tumor cells. This report is the first demonstrating a partial remission of a pancreatic NEN using pembrolizumab monotherapy with a hepatic tumor volume reduction of at least 66%, combined with an improvement of the Karnofsky score rising from 60% to 100%. This case offers insight into the potential role of immunotherapy in a subgroup of neuroendocrine neoplasms.

Role of tumor gene mutations in treatment response to immune checkpoint blockades

Early studies shed light on the immune suppression of immune checkpoint molecules in the cancer microenvironment, with later studies applying immune checkpoint blockade (ICB) in treatment of various malignancies. Despite the encouraging efficacy of ICBs in a substantial subset of cancer patients, the treatment response varies. Gene mutations of both tumor cells and immune cells in the tumor microenvironment have recently been identified as potential predictors of the ICB response. Recent developments in gene expression profiling of tumors have allowed identification of a panel of mutated genes that may affect tumor cell response to ICB treatment. In this review, we discuss the association of the ICB response with gene expression and mutation profiles in tumor cells, which it is hoped will help to optimize the clinical application of ICBs in cancer patients.

First-line therapy-stratified survival in BRAF-mutant melanoma: a retrospective multicenter analysis

BACKGROUND

Inhibition of the mitogen-activated protein kinase (MAPK) pathway as well as programmed death 1 receptor (PD-1) blockade was shown to prolong overall survival (OS) in patients with advanced B-Raf proto-oncogene (BRAF)-mutant melanoma. However, due to the lack of head-to-head trials, it remains unclear if one of these therapeutic approaches should be preferred in first-line therapy. Here, we present a retrospective analysis comparing anti-PD-1 monotherapy with BRAF/MAPK/ERK kinase (MEK) combined inhibition used as first-line agents in a real-world clinical setting.

PATIENTS AND METHODS

Clinical data, routine blood counts and lactate dehydrogenase (LDH) levels of 301 patients with unresectable or metastatic melanoma harboring an activating mutation in BRAF (V600E/K) were included. Of these, 106 received anti-PD-1 antibodies, while 195 patients were treated with a selective BRAF inhibitor combined with an MEK inhibitor as palliative first-line therapy. Patients were sub-grouped according to previously described predictive and prognostic markers.

RESULTS

OS was significantly longer in patients receiving anti-PD-1 monotherapy compared to patients receiving combined MAPK inhibitors. Subsequent therapies were comparable among these groups. The difference in OS was less pronounced in patients with high LDH levels and visceral metastatic spread.

CONCLUSION

First-line treatment with a PD-1 blocking antibody might be associated with longer OS than first-line inhibition of the MAPK pathway in patients with advanced melanoma harboring mutant BRAF. These hypothesis-generating data need to be confirmed or rejected in prospective, randomized trials.

Predictive biomarkers for PD-1 and PD-L1 immune checkpoint blockade therapy

The immune system is very important for monitoring and eradicating cancer cells. However, there may be multiple immunosuppressive mechanisms to prevent effective antitumor immunity in the tumor environment, such as the negative immunologic regulators known as checkpoints. Antibodies that block the checkpoints programmed cell death protein 1 (PD-1) pathway have made great success. Nevertheless, the response rates are likely to vary widely. Therefore, several researches are currently underway to determine which biomarkers are able to identify the group of patients who can obtain benefits from PD-1 and programmed cell death-ligand 1 (PD-L1) immune checkpoint blockade therapy. This review focuses on potential predictive biomarkers for PD-1/PD-L1 checkpoint blockade immunotherapy in order to provide advice and guidance for clinical treatment.

PD-L1 expression combined with microsatellite instability/CD8+ tumor infiltrating lymphocytes as a useful prognostic biomarker in gastric cancer

While the importance of programmed death-ligand 1 (PD-L1), mutation burden caused by microsatellite instability (MSI), and CD8+ tumor infiltrating lymphocytes (TILs) has become evident, the significance of PD-L1 expression on prognosis still remains controversial. We evaluated the usefulness of combined markers of PD-L1 and MSI or CD8+ TILs as a prognostic biomarker in gastric cancer. A total of 283 patients with gastric cancer were reviewed retrospectively. PD-L1 expression on >5% tumor cells was defined as PD-L1-positive. PD-L1-positive rate was 15.5% (44/283). PD-L1 positivity was significantly correlated with invasive and advanced cancer and also significantly correlated with MSI, whereas no significance was observed with CD8+ TILs. Kaplan-Meier analysis showed that PD-L1 positivity significantly correlated with a poor prognosis (p = 0.0025). Multivariate analysis revealed that PD-L1 positivity was an independent poor prognostic factor (hazard ratio [HR]: 1.97, p = 0.0106) along with diffuse histological type and lymph node metastases. Combinations of PD-L1 and MSI (HR: 2.18) or CD8+ TILs (HR: 2.57) were stronger predictive factors for prognosis than PD-L1 alone. In conclusion, combined markers of PD-L1 and MSI or CD8+ TILs may be more useful prognostic biomarkers in gastric cancer, and better clarify the immune status of gastric cancer patients.

Immune Cell Infiltration of the Primary Tumor, Not PD-L1 Status, Is Associated With Improved Response to Checkpoint Inhibition in Metastatic Melanoma

Immune checkpoint inhibition has resulted in dramatic improvements in overall and relapse-free survival in patients with metastatic melanoma. The most commonly used immune checkpoint inhibitors are monoclonal antibodies targeting programmed cell death protein 1 and cytotoxic T-lymphocyte-associated protein 4. Unfortunately, a significant subset of patients fail to respond to these therapies, which has resulted in intense research efforts to identify the factors which are associated with treatment response. To this end, we investigated immune cell infiltration in primary melanomas and melanoma metastases, in addition to tumor cell PD-L1 expression, to determine whether these factors are associated with an improved outcome after immune checkpoint inhibition. Indeed, the extent of the immune cell infiltration in the primary melanoma, measured by the Immunoscore, was associated with a significantly improved response to immune checkpoint inhibition in terms of increased overall survival. However, the Immunoscore did not predict which patients would respond to treatment. The Immunoscore was significantly reduced in metastases when compared to primary melanomas. In contrast, PD-L1 expression, exhaustively tested using four commercially available anti-PD-L1 clones, did not differ significantly between primary tumors and melanoma metastases and was not associated treatment response. Whilst replication in larger, prospective studies is required, our data demonstrates the relevance of immune cell infiltration in the primary melanoma as a novel marker of improved overall survival in response to immune checkpoint inhibition.

Autoimmune genetic risk variants as germline biomarkers of response to melanoma immune-checkpoint inhibition

Immune-checkpoint inhibition (ICI) treatments improve outcomes for metastatic melanoma; however, > 60% of treated patients do not respond to ICI. Current biomarkers do not reliably explain ICI resistance. Given the link between ICI and autoimmunity, we investigated if genetic susceptibility to autoimmunity modulates ICI efficacy. In 436 patients with metastatic melanoma receiving single line ICI or combination treatment, we tested 25 SNPs, associated with > 2 autoimmune diseases in recent genome-wide association studies, for modulation of ICI efficacy. We found that rs17388568-a risk variant for allergy, colitis and type 1 diabetes-was associated with increased anti-PD-1 response, with significance surpassing multiple testing adjustments (OR 0.26; 95% CI 0.12-0.53; p = 0.0002). This variant maps to a locus of established immune-related genes: IL2 and IL21. Our study provides first evidence that autoimmune genetic susceptibility may modulate ICI efficacy, suggesting that systematic testing of autoimmune risk loci could reveal personalized biomarkers of ICI response.

Genomic correlates of response to immune checkpoint blockade

Despite impressive durable responses, immune checkpoint inhibitors do not provide a long-term benefit to the majority of patients with cancer. Understanding genomic correlates of response and resistance to checkpoint blockade may enhance benefits for patients with cancer by elucidating biomarkers for patient stratification and resistance mechanisms for therapeutic targeting. Here we review emerging genomic markers of checkpoint blockade response, including those related to neoantigens, antigen presentation, DNA repair, and oncogenic pathways. Compelling evidence also points to a role for T cell functionality, checkpoint regulators, chromatin modifiers, and copy-number alterations in mediating selective response to immune checkpoint blockade. Ultimately, efforts to contextualize genomic correlates of response into the larger understanding of tumor immune biology will build a foundation for the development of novel biomarkers and therapies to overcome resistance to checkpoint blockade.

Combinatorial Approach to Improve Cancer Immunotherapy: Rational Drug Design Strategy to Simultaneously Hit Multiple Targets to Kill Tumor Cells and to Activate the Immune System

Cancer immunotherapy, including immune checkpoint blockade and adoptive CAR T-cell therapy, has clearly established itself as an important modality to treat melanoma and other malignancies. Despite the tremendous clinical success of immunotherapy over other cancer treatments, this approach has shown substantial benefit to only some of the patients while the rest of the patients have not responded due to immune evasion. In recent years, a combination of cancer immunotherapy together with existing anticancer treatments has gained significant attention and has been extensively investigated in preclinical or clinical studies. In this review, we discuss the therapeutic potential of novel regimens combining immune checkpoint inhibitors with therapeutic interventions that (1) increase tumor immunogenicity such as chemotherapy, radiotherapy, and epigenetic therapy; (2) reverse tumor immunosuppression such as TAMs, MDSCs, and Tregs targeted therapy; and (3) reduce tumor burden and increase the immune effector response with rationally designed dual or triple inhibitory chemotypes.

Endocrine Toxicity of Cancer Immunotherapy Targeting Immune Checkpoints

Immune checkpoints are small molecules expressed by immune cells that play critical roles in maintaining immune homeostasis. Targeting the immune checkpoints cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed death 1 (PD-1) with inhibitory antibodies has demonstrated effective and durable antitumor activity in subgroups of patients with cancer. The US Food and Drug Administration has approved several immune checkpoint inhibitors (ICPis) for the treatment of a broad spectrum of malignancies. Endocrinopathies have emerged as one of the most common immune-related adverse events (irAEs) of ICPi therapy. Hypophysitis, thyroid dysfunction, insulin-deficient diabetes mellitus, and primary adrenal insufficiency have been reported as irAEs due to ICPi therapy. Hypophysitis is particularly associated with anti-CTLA-4 therapy, whereas thyroid dysfunction is particularly associated with anti-PD-1 therapy. Diabetes mellitus and primary adrenal insufficiency are rare endocrine toxicities associated with ICPi therapy but can be life-threatening if not promptly recognized and treated. Notably, combination anti-CTLA-4 and anti-PD-1 therapy is associated with the highest incidence of ICPi-related endocrinopathies. The precise mechanisms underlying these endocrine irAEs remain to be elucidated. Most ICPi-related endocrinopathies occur within 12 weeks after the initiation of ICPi therapy, but several have been reported to develop several months to years after ICPi initiation. Some ICPi-related endocrinopathies may resolve spontaneously, but others, such as central adrenal insufficiency and primary hypothyroidism, appear to be persistent in most cases. The mainstay of management of ICPi-related endocrinopathies is hormone replacement and symptom control. Further studies are needed to determine (i) whether high-dose corticosteroids in the treatment of ICPi-related endocrinopathies preserves endocrine function (especially in hypophysitis), and (ii) whether the development of ICPi-related endocrinopathies correlates with tumor response to ICPi therapy.

Programmed cell death-1/programmed cell death ligand-1 checkpoint inhibitors: differences in mechanism of action

Programmed cell death-1 (PD-1)/programmed death-ligand 1 (PD-L1) checkpoint inhibitors are widely used in many types of solid tumors, and are often considered to be in the same immunotherapy subclass. This review explores whether specific agents in these two categories exhibit differences in their mechanism of action, pharmacokinetics and pharmacodynamics, and clinical efficacy and safety. Due to the complicated functional pathways in the immune checkpoint system, the epitopes, interfaces and signal pathways between PD-1: PD-L1/PD-L2, PD-L1/CD28/CTLA-4: B7-1 axes often overlap and affect each other. Therefore, the mechanisms of action of PD-1 and PD-L1 inhibitors reflect the corresponding cross connectivity and their unique characteristics. Only head-to-head comparative studies can provide definitive information regarding clinical efficacy and safety differences between specific PD-1/PD-L1 inhibitors.

Radiological Features of Programmed Cell Death-Ligand 2-positive Lung Adenocarcinoma: A Single-institution Retrospective Study

AIM

Programmed cell death-ligand 1 and 2 (PD-L1 and PD-L2) are ligands of the programmed cell death-1 (PD1) receptor. PD1/PD-L1 inhibitors have shown clinical efficacy in non-small cell lung cancer (NSCLC). However, relatively little is known about the expression of PD-L2, or its association with the clinicopathological features of NSCLC. Here, the radiological features of PD-L2-positive lung adenocarcinoma were evaluated.

MATERIALS AND METHODS

PD-L1 and PD-L2 expression were evaluated by immunohistochemical staining of surgically-resected specimens from 393 patients with primary lung adenocarcinoma who underwent preoperative thin-section computed tomography (CT), 222 of whom also underwent ¹⁸F-fluorodeoxyglucose positron-emission tomography/CT (¹⁸F-FDG-PET/CT).

RESULTS

Among the 393 specimens, 132 (33.6%) and 266 (67.7%) were positive for PD-L1 and PD-L2 expression, respectively. Multivariate analysis showed that the absence of surrounding ground glass opacity and the presence of air bronchogram were significantly associated with PD-L2 expression; however, there was no significant association between PD-L2 expression and the consolidation/tumor ratio. In 222 ¹⁸F-FDG-PET/CT, the maximum standardized uptake value was significantly higher in patients with PD-L2-positive compared to those with PD-L2-negative tumors.

CONCLUSION

PD-L2-positive lung adenocarcinomas are less radiologically malignant and invasive than their PD-L1-positive counterparts.

Phase I/II trial of Durvalumab plus Tremelimumab and stereotactic body radiotherapy for metastatic head and neck carcinoma

BACKGROUND

The efficacy of immunotherapy targeting the PD-1/PD-L1 pathway has previously been demonstrated in metastatic head and neck squamous cell carcinoma (HNSCC). Stereotactic Body Radiotherapy (SBRT) aims at ablating metastatic lesions and may play a synergistic role with immunotherapy. The purpose of this study is to assess the safety and efficacy of triple treatment combination (TTC) consisting of the administration of durvalumab and tremelimumab in combination with SBRT in metastatic HNSCC.

METHOD

This is a phase I/II single arm study that will include 35 patients with 2-10 extracranial metastatic lesions. Patients will receive durvalumab (1500 mg IV every 4 weeks (Q4W)) and tremelimumab (75 mg IV Q4W for a total of 4 doses) until progression, unacceptable toxicity or patient withdrawal. SBRT to 2-5 metastases will be administered between cycles 2 and 3 of immunotherapy. The safety of the treatment combination will be evaluated through assessment of TTC-related toxicities, defined as grade 3-5 toxicities based on Common Terminology Criteria for Adverse Events (v 4.03), occurring within 6 weeks from SBRT start, and that are definitely, probably or possibly related to the combination of all treatments. We hypothesize that dual targeting of PD-L1 and CTLA-4 pathways combined with SBRT will lead to < 35% grade 3-5 acute toxicities related to TTC. Progression free survival (PFS) will be the primary endpoint of the phase II portion of this study and will be assessed with radiological exams every 8 weeks using the RECIST version 1.1 criteria.

DISCUSSION

The combination of synergistic dual checkpoints inhibition along with ablative radiation may significantly potentiate the local and systemic disease control. This study constitutes the first clinical trial combining effects of SBRT with dual checkpoint blockade with durvalumab and tremelimumab in the treatment of metastatic HNSCC. If positive, this study would lead to a phase III trial testing this treatment combination against standard of care in metastatic HNSCC.

TRIAL REGISTRATION

NCT03283605 . Registration date: September 14, 2017; version 1.

New frontiers in precision medicine for sepsis-induced immunoparalysis

INTRODUCTION

In the last decade, the sepsis research field has shifted focus from targeting hyperinflammation to reversing sepsis-induced immunoparalysis. Sepsis-induced immunoparalysis is very heterogeneous: the magnitude and the nature of the underlying immune defects differ considerably between patients, but also within individuals over time. Therefore, a 'one-treatment-fits-all' strategy for sepsis-induced immunoparalysis is bound to fail, and an individualized 'precision medicine' approach is required. Such a strategy is nevertheless hampered by the unsuitability of the currently available markers to identify the many immune defects that can manifest in individual patients. Areas covered: We describe the currently available markers for sepsis-induced immunoparalysis and limitations pertaining to their use. Furthermore, future prospects and caveats are discussed, focusing on 'omics' approaches: genomics, transcriptomics, epigenomics, and metabolomics. Finally, we present a contemporary overview of adjuvant immunostimulatory therapies. Expert opinion: The integration of multiple omics techniques offers a systems biology approach which can yield biomarker profiles that accurately and comprehensively gauge the extent and nature of sepsis-induced immunoparalysis. We expect this development to be instrumental in facilitating precision medicine for sepsis-induced immunoparalysis, consisting of the application of targeted immunostimulatory therapies and follow-up measurements to monitor the response to treatment and to titrate or adjust medication.

Targeting CXCL12/CXCR4 Axis in Tumor Immunotherapy

Chemokines, which have chemotactic abilities, are comprised of a family of small cytokines with 8-10 kilodaltons. Chemokines work in immune cells by trafficking and regulating cell proliferation, migration, activation, differentiation, and homing. CXCR-4 is an alpha-chemokine receptor specific for stromal-derived-factor-1 (SDF-1, also known as CXCL12), which has been found to be expressed in more than 23 different types of cancers. Recently, the SDF-1/CXCR-4 signaling pathway has emerged as a potential therapeutic target for human tumor because of its critical role in tumor initiation and progression by activating multiple signaling pathways, such as ERK1/2, ras, p38 MAPK, PLC/ MAPK, and SAPK/ JNK, as well as regulating cancer stem cells. CXCL12/CXCR4 antagonists have been produced, which have shown encouraging results in anti-cancer activity. Here, we provide a brief overview of the CXCL12/CXCR4 axis as a molecular target for cancer treatment. We also review the potential utility of targeting CXCL12/CXCR4 axis in combination of immunotherapy and/or chemotherapy based on up-to-date literature and ongoing research progress.

Molecular characterization of cancers with NTRK gene fusions

Targeted inhibitors of neurotropic tyrosine kinases are highly effective in selected patients with gene fusions involving NTRK1, NTRK2, or NTRK3. These fusions are consistently detected in rare cancer types (e.g., secretory breast carcinoma and congenital infantile fibrosarcoma), but the occurrence of NTRK fusions in common cancers and their relationship to other therapy biomarkers are largely unexplored. Tissue samples from 11,502 patients were analyzed for 53 gene fusions and sequencing of 592 genes, along with an immunohistochemical evaluation of TrkA/B/C and PD-L1. Thirty-one cases (0.27% of the entire cohort) had NTRK fusions. The most common fusions were ETV6:NTRK3 (n = 10) and TPM3:NTRK1 (n = 6). Gliomas had the highest number of NTRK fusions (14/982, 1.4%), most commonly involving NTRK2 (n = 9). Seventeen non-glioma cases with NTRK fusions included carcinomas of the lungs, thyroid, breast, cervix, colon, nasal cavity, cancer of unknown primary and soft tissue sarcomas. Strong and uniform Trk expression detected with a pan-Trk immunohistochemistry characterized 7/8 NTRK1 fusion cases and 8/9 NTRK2 fusion cases, while NTRK3 fused cases were positive in 6/11 (55%) of cases. 29% of NTRK fusion cases had no other pathogenic genomic alteration. PD-L1 expression was observed in 23% of NTRK fused cases while high tumor DNA microsatellite instability was detected in two cases. We confirm the rarity of NTRK genes fusions outside the brain malignancies. NTRK inhibitors alone or combined with immune checkpoint inhibitors may be a therapeutic option for a substantial proportion of these patients. Strategies for detection of the NTRK fusion-driven cancers may include immunohistochemistry, but gene fusion detection remains the most reliable tool.

Dynamic metrics-based biomarkers to predict responders to anti-PD-1 immunotherapy

Background

Anti-PD-1 immunotherapies have shown clinical benefit in multiple cancers, but response was only observed in a subset of patients. Predicting which patients will respond is an urgent clinical need, but current companion diagnosis based on PD-L1 IHC staining shows limited predictability.

Methods

A dynamic, metrics-based biomarker was developed to discriminate responders from non-responders for anti-PD-1 immunotherapy in B16F10 melanoma-bearing mice.

Results

Similar to patients, there was considerable heterogeneity in response to anti-PD-1 immunotherapy in mice. Compared with the control group, 45% of anti-PD-1 antibody-treated mice displayed improved survival (defined as responders) and the remainder only gained little, if any, survival benefit from PD-1 blockade (non-responders). Interestingly, the dynamics of IFN-γ secretion by peripheral lymphocytes was associated with faster secretion onset (shorter lag time), stronger exponential phase, shorter time to half magnitude, and higher magnitude of secretion in responders at day 10 after tumour inoculation. To sufficiently predict responders from non-responders, IFN-γ secretion descriptors as well as phenotypic markers were subjected to multivariate analysis using orthogonal partial least-squares discriminant analysis (OPLS-DA).

Conclusions

By integrating phenotypic markers, IFN-γ secretion descriptors sufficiently predict response to anti-PD-1 immunotherapy. Such a dynamic, metrics-based biomarker holds high diagnostic potential for anti-PD-1 checkpoint immunotherapy.

T-Cell-Inflamed Gene-Expression Profile, Programmed Death Ligand 1 Expression, and Tumor Mutational Burden Predict Efficacy in Patients Treated With Pembrolizumab Across 20 Cancers: KEYNOTE-028

PURPOSE

Biomarkers that can predict response to anti-programmed cell death 1 (PD-1) therapy across multiple tumor types include a T-cell-inflamed gene-expression profile (GEP), programmed death ligand 1 (PD-L1) expression, and tumor mutational burden (TMB). Associations between these biomarkers and the clinical efficacy of pembrolizumab were evaluated in a clinical trial that encompassed 20 cohorts of patients with advanced solid tumors.

METHODS

KEYNOTE-028 ( ClinicalTrials.gov identifier: NCT02054806) is a nonrandomized, phase Ib trial that enrolled 475 patients with PD-L1-positive advanced solid tumors who were treated with pembrolizumab 10 mg/kg every 2 weeks for 2 years or until confirmed disease progression or unacceptable toxicity occurred. The primary end point was objective response rate (ORR; by RECIST v1.1, investigator review). Secondary end points included safety, progression-free survival (PFS), and overall survival (OS). Relationships between T-cell-inflamed GEP, PD-L1 expression, and TMB and antitumor activity were exploratory end points.

RESULTS

ORRs (with 95% CIs) ranged from 0% (0.0% to 14.2%) in pancreatic cancer to 33% (15.6% to 55.3%) in small-cell lung cancer. Across cohorts, median (95% CI) PFS ranged from 1.7 months (1.5 to 2.9 months) to 6.8 months (1.9 to 14.1 months) in pancreatic and thyroid cancers, respectively, and median OS from 3.9 months (2.8 to 5.5 months) to 21.1 months (9.1 to 22.4 months) in vulvar and carcinoid tumors, respectively. Higher response rates and longer PFS were demonstrated in tumors with higher T-cell-inflamed GEP, PD-L1 expression, and/or TMB. Correlations of TMB with GEP and PD-L1 were low. Response patterns indicate that patients with tumors that had high levels of both TMB and inflammatory markers (GEP or PD-L1) represent a population with the highest likelihood of response. Safety was similar and consistent with prior pembrolizumab reports.

CONCLUSION

A T-cell--inflamed GEP, PD-L1 expression, and TMB predicted response to pembrolizumab in multiple tumor types. These biomarkers (alone/in combination) may help identify patients who have a higher likelihood of response to anti-PD-1 therapies across a broad spectrum of cancers.

Organoid Modeling of the Tumor Immune Microenvironment

In vitro cancer cultures, including three-dimensional organoids, typically contain exclusively neoplastic epithelium but require artificial reconstitution to recapitulate the tumor microenvironment (TME). The co-culture of primary tumor epithelia with endogenous, syngeneic tumor-infiltrating lymphocytes (TILs) as a cohesive unit has been particularly elusive. Here, an air-liquid interface (ALI) method propagated patient-derived organoids (PDOs) from >100 human biopsies or mouse tumors in syngeneic immunocompetent hosts as tumor epithelia with native embedded immune cells (T, B, NK, macrophages). Robust droplet-based, single-cell simultaneous determination of gene expression and immune repertoire indicated that PDO TILs accurately preserved the original tumor T cell receptor (TCR) spectrum. Crucially, human and murine PDOs successfully modeled immune checkpoint blockade (ICB) with anti-PD-1- and/or anti-PD-L1 expanding and activating tumor antigen-specific TILs and eliciting tumor cytotoxicity. Organoid-based propagation of primary tumor epithelium en bloc with endogenous immune stroma should enable immuno-oncology investigations within the TME and facilitate personalized immunotherapy testing.

Cytokines, Chemokines, and Other Biomarkers of Response for Checkpoint Inhibitor Therapy in Skin Cancer

Immunotherapy for skin malignancies has ushered in a new era for cancer treatments by demonstrating unprecedented durable responses in the setting of metastatic Melanoma. Consequently, checkpoint inhibitors are now the first-line treatment of metastatic melanoma and widely used as adjuvant therapy for stage III disease. With the observation that higher tumor mutational burden correlates with a better response, checkpoint inhibitors are tested in other skin cancer types of known high tumor mutational burden with promising results and recently became the first-ever FDA-approved treatment for metastatic Merkel cell carcinoma. The emerging new standards-of-care will necessitate more precise biomarkers and predictors for treatment response and immune-related adverse events. Measurable immune-related mediators are currently under investigation as factors that promote or block the response to cancer immunotherapy and may provide insights into the underlying immune response to the tumor. Cytokines and chemokines are such mediators and are crucial for facilitating the recruitment and activation of specific subsets of leukocytes within the microenvironment of skin cancers. The exact mechanisms of how these meditators, both immunological and non-immunological, operate in the tumor microenvironment is an area of active research, so to reliable biomarkers of responses to cancer immunotherapy. Here, we will review and summarize the expanding body of literature for immune-related biomarkers pertaining to Melanoma, Basal cell carcinoma, Squamous cell carcinoma, and Merkel cell carcinoma, highlighting clinically relevant checkpoint inhibitor therapy biomarker advancements.

Immunotherapy in Older Adults With Advanced Cancers: Implications for Clinical Decision-Making and Future Research

Immunotherapy has expanded the therapeutic landscape for advanced cancers, including solid tumors and lymphomas. For many patients with cancer, these agents have been shown to have substantial efficacy and favorable toxicity compared with cytotoxic agents, particularly in the second-line setting. With the advent of anti-PD-1 and anti-PD-L1 checkpoint inhibitors, combination immunotherapy- and chemoimmunotherapy-based strategies have emerged as promising novel regimens to improve cancer-related outcomes. Older adults age 65 or older represent the growing majority of patients diagnosed with cancer. However, older adults are under-represented in clinical trials in general, as well as in the landmark studies that led to approval of these immunotherapy agents. Because of increasing age and attendant multimorbidity and impaired functional status, many of these patients seen in the community-based oncology practices would not have been considered eligible for such studies. Thus, the results of these studies are difficult to generalize to a broader patient population with these competing risks. Furthermore, robust evaluation of toxicities, effect on quality of life and functional status, and aging-related (i.e., immunosenescence) and immunotherapy-related changes affecting the immune system remain underexplored research areas for older adults. This review examines the role of immunotherapy and its unique issues, specifically in older adults with lung cancer, bladder cancer, and lymphomas.

Analytical Validation and Clinical Utility of an Immunohistochemical Programmed Death Ligand-1 Diagnostic Assay and Combined Tumor and Immune Cell Scoring Algorithm for Durvalumab in Urothelial Carcinoma

Context.—

Clinical responses to anti–programmed death receptor-1 and anti–programmed death ligand-1 (PD-L1) agents are generally improved in patients with high PD-L1 expression compared with those with low/negative expression across several tumor types, including urothelial carcinoma.

Objective.—

To validate a PD-L1 immunohistochemical diagnostic test in urothelial carcinoma patients treated with the anti–PD-L1 monoclonal antibody durvalumab.

Design.—

The Ventana PD-L1 (SP263) assay was validated for intended use in urothelial carcinoma formalin-fixed, paraffin-embedded samples in studies addressing sensitivity, specificity, robustness, and precision, and implemented in study CD-ON-MEDI4736-1108 (NCT01693562). Efficacy was analyzed in patients classified according to prespecified PD-L1 expression cutoffs: PD-L1 high (if &gt;1% of the tumor area contained tumor-associated immune cells, ≥25% of tumor cells or ≥25% of immune cells stained for PD-L1; if ≤1% of the tumor area contained immune cells, ≥25% of tumor cells or 100% of immune cells stained for PD-L1) and PD-L1 low/negative (did not meet criteria for PD-L1 high).

Results.—

The assay met all predefined acceptance criteria for sensitivity, specificity, and precision. Interreader and intrareader precision overall agreement were 93.0% and 92.4%, respectively. For intraday reproducibility and interday precision, overall agreement was 99.2% and 100%, respectively. Interlaboratory overall agreement was 92.6%. In study CD-ON-MEDI4736-1108, durvalumab demonstrated clinical activity and durable responses in both PD-L1–high and PD-L1–low/negative subgroups, although objective response rates tended to be higher in the PD-L1–high subgroup than in the PD-L1–low/negative subgroup.

Conclusions.—

Determination of PD-L1 expression in urothelial carcinoma patients using the Ventana PD-L1 (SP263) assay was precise, highly reproducible, and clinically relevant.

Implications of Programmed Death Ligand-1 Positivity in Non-Clear Cell Renal Cell Carcinoma

The purpose of this study was to assess the prognostic value of programmed death ligand-1 (PD-L1) positivity in a non-clear cell renal cell carcinoma (non-ccRCC) cohort. PD-L1 expression was evaluated by immunohistochemistry (IHC) using formalin-fixed paraffin-embedded (FFPE) specimens from 45 non-ccRCC patients with available tissue. PD-L1 positivity was defined as ≥1% of staining. Histopathological characteristics and oncological outcomes were correlated to PD-L1 expression. Cancer-specific survival (CSS) and recurrence-free survival (RFS) stratified by PD-L1 status were estimated using the Kaplan-Meier method. Median age was 58 years and median follow-up was 40 months. Non-ccRCC subtypes included sarcomatoid (n = 9), rhabdoid (n = 6), medullary (n = 2), Xp11.2 translocation (n = 2), collecting duct (n = 1), papillary type I (n = 11), and papillary type II (n = 14). PD-L1 positivity was noted in nine (20%) patients. PD-L1 positivity was significantly associated with higher Fuhrman nuclear grade (P = 0.048) and perineural invasion (P = 0.043). Five-year CSS was 73.2 and 83% for PD-L1 positive and negative tumors, respectively (P = 0.47). Five-year RFS was 55.6 and 61.5% for PD-L1 positive and negative tumors, respectively (P = 0.58). PD-L1 was expressed in a fifth of non-ccRCC cases and was associated with adverse histopathologic features. Expression of biomarkers such PD-L1 may help better risk-stratify non-ccRCC patients to guide treatment decisions and follow-up strategies.

3D microfluidic ex vivo culture of organotypic tumor spheroids to model immune checkpoint blockade

Microfluidic culture has the potential to revolutionize cancer diagnosis and therapy. Indeed, several microdevices are being developed specifically for clinical use to test novel cancer therapeutics. To be effective, these platforms need to replicate the continuous interactions that exist between tumor cells and non-tumor cell elements of the tumor microenvironment through direct cell-cell or cell-matrix contact or by the secretion of signaling factors such as cytokines, chemokines and growth factors. Given the challenges of personalized or precision cancer therapy, especially with the advent of novel immunotherapies, a critical need exists for more sophisticated ex vivo diagnostic systems that recapitulate patient-specific tumor biology with the potential to predict response to immune-based therapies in real-time. Here, we present details of a method to screen for the response of patient tumors to immune checkpoint blockade therapy, first reported in Jenkins et al. Cancer Discovery, 2018, 8, 196-215, with updated evaluation of murine- and patient-derived organotypic tumor spheroids (MDOTS/PDOTS), including evaluation of the requirement for 3D microfluidic culture in MDOTS, demonstration of immune-checkpoint sensitivity of PDOTS, and expanded evaluation of tumor-immune interactions using RNA-sequencing to infer changes in the tumor-immune microenvironment. We also examine some potential improvements to current systems and discuss the challenges in translating such diagnostic assays to the clinic.

DNA repair defects and implications for immunotherapy

A complex DNA repair machinery has evolved to protect genomic integrity in the face of a myriad of DNA damage sources. When DNA repair fails, this damage can lead to carcinogenesis and tumor genomic instability. Indeed, many heritable cancer predisposition syndromes are attributable to germline defects in DNA repair pathways. On the other hand, these defects may also portend particular vulnerabilities of the cancer and may be exploited therapeutically. Most recently this has been demonstrated in the case of mismatch repair-deficient cancers, in which the immune checkpoint inhibitors have been demonstrated to be highly active. This observation has paved the way for further research investigating other sources of genomic instability that may serve as biomarkers to select patients for immunotherapy.

Antitumor effects of the silencing of programmed cell death ligand 1 in colorectal cancer via immunoregulation

Activation of programmed cell death 1 (PD-1)/PD-ligand 1 (PD-L1) can promote immune suppression of the tumor microenvironment. However, the effects and mechanisms of PD-L1 silencing on colorectal cancer growth are largely unknown. In the present study, PD-L1 expression was compared in colorectal cancer and paracancerous tissues by immunofluorescence. A stable colorectal carcinoma cell line encoding PD-L1 short hairpin RNA (shRNA) was established. Thereafter, inoculated tumors were modeled in C57B/L6 mice. Experiments were divided into 3 groups: Control group, vector group, and PD-L1 silencing group (inoculated with the stable CT26 cell line encoding PD-L1 shRNA). Following decapitation of the mice, tumors were weighed and apoptosis of tumor cells was detected. The number and viability of cluster of differentiation (CD)4⁺ and CD8⁺ T cells were analyzed by flow cytometry and a cell counting kit assay, respectively. Compared with paracancerous tissue, colorectal cancer tissue extensively expressed PD-L1, RAC-α serine/threonine-protein kinase (AKT), and phosphatidylinositol 3-kinase (PI3K). Lymphocyte-activating gene 3 (LAG-3) expression was observed at the edge of tumor tissue, but rarely observed in paracancerous tissue. A stable CT26 cell line encoding PD-L1 shRNA was established, and lack of PD-L1 expression was confirmed by reverse transcription-polymerase chain reaction and western blotting. Compared with the control, the shPD-L1 group demonstrated reduced tumor growth, a high level of apoptosis in tumor cells, a low level of PI3K and AKT expression, and an increased number of cells and greater activity of CD4⁺ T and CD8⁺ T cells. Taken together, PD-L1 silencing promoted tumor cell apoptosis, at least in part, through the activation of CD4⁺ and CD8⁺ T cells.

Avoiding chemotherapy for advanced nononcogene addicted NSCLC overexpressing PD-L1: Rule or option?

Patients with nonsmall-cell lung cancers expressing high levels of PD-L1 present a therapeutic dilemma for clinicians who have to choose between pembrolizumab as a single agent or in combination with chemotherapy. In order to help them as they ponder over this decision we performed a meta-analysis using the data available from randomized clinical trials that enrolled patients with untreated advanced nonsmall-cell lung cancers with PD-L1 expression level ≥50%. We evaluated interactions according to type of treatment-add-on strategy: pembrolizumab plus chemotherapy versus chemotherapy or head-to-head strategy: pembrolizumab alone versus chemotherapy. Hazard and Odds Ratios (HR/OR) for primary (overall survival, OS) and secondary endpoints (progression-free survival, PFS and objective response rate, ORR) were extracted and cumulated by adopting a random-effect model with 95% confidence interval. Four clinical trials that enrolled 2,754 patients including 1,252 with PD-L1 expression in ≥50% of cells were examined. We did not find a significant interaction (P = 0.16) between an add-on strategy and head-to-head comparisons with pembrolizumab for OS (HRs in favor of immunotherapy of 0.50 and 0.67, respectively). A significant quantitative interaction favoring the add-on strategy was found for PFS and ORR (P < 0.001), with a HR for PFS of 0.36 with the add-on strategy and 0.65 in head-to head comparisons, and an OR for ORR of 5.35 and 1.58, respectively. In absence of planned prospective noninferiority trials addressing this issue, addition of chemotherapy to pembrolizumab appears to decrease tumor size and delay disease progression significantly more than pembrolizumab alone, but has no impact on OS. We conclude that the data support deciding between both treatment options on an individual basis by considering a patients' clinical status and disease characteristics.

Prognostic Factors for Checkpoint Inhibitor Based Immunotherapy: An Update With New Evidences

Checkpoint inhibitor (CPI) based immunotherapy (i.e., anit-CTLA-4/PD-1/PD-L1 antibodies) can effectively prolong overall survival of patients across several cancer types at the advanced stage. However, only part of patients experience objective responses from such treatments, illustrating large individual differences in terms of both efficacy and adverse drug reactions. Through the observation on a series of CPI based clinical trials in independent patient cohorts, associations of multiple clinical and molecular characteristics with CPI response rate have been determined, including microenvironment, genomic alterations of the cancer cells, and even gut microbiota. A broad interest has been drawn to the question whether and how these prognostic factors can be used as biomarkers for optimal usage of CPIs in precision immunotherapy. Therefore, we reviewed the candidate prognostic factors identified by multiple trials and the experimental investigations, especially those reported in the recent 2 years, and described the possibilities and problems of them in routine clinical usage of cancer treatment as biomarkers.

PD-L1 expression with immune-infiltrate evaluation and outcome prediction in melanoma patients treated with ipilimumab

Background: Tumor microenvironment may have a key role in providing immunological markers that can help predict clinical response to treatment with checkpoint inhibitors. We investigated whether the baseline expression of PD-L1 in advanced melanoma patients treated with ipilimumab may correlate with clinical outcome. Methods: PD-L1 expression was assessed in 114 patients with advanced melanoma treated with ipilimumab and, in a cohort of 77 patients, a comprehensive assessment using multispectral imaging to assess the presence and distribution of CD3+, CD8+, CD163+, FOXP3+ and PD-L1+ cells inside and at periphery of the tumor was performed. Results: PD-L1 status alone was not a predictive biomarker for response or survival. There was an association between clinical benefit from ipilimumab therapy with the coexistence of low densities of CD8+ and high densities of CD163+ PD-L1+ cells at the periphery of the tumor. Conclusions: To explain the association of this peculiar microenvironment with clinical benefit from ipilimumab, we proposed a model where baseline CD8 cells levels are low due to inhibitory effect of Tregs and to pro-tumor activity of TAM M2 (CD163+ PD-L1+ cells). Ipilimumab treatment causes a decrease of Treg cells, mediated by ADCC from macrophages, with a concomitant change in TAM polarization that switches from M2 to M1 with a subsequent attraction of CD8 cells and the increase of antitumor response.

Impact of lenalidomide use among non-transfusion dependent patients with myelodysplastic syndromes

Chemotherapies approved for defined subgroups promise personalized oncologic care, but their off-label impact is unclear. Lenalidomide is approved for lower-risk, transfusion-dependent (TD) myelodysplastic syndromes (MDS) with del(5q), but frequently used in MDS outside this indication. We characterized lenalidomide use and outcomes among non-TD patients with MDS. Patients 65 or older diagnosed with MDS between 2007 and 2013 were identified using SEER; linked Medicare claims were evaluated for transfusions, lenalidomide use, and incident toxicities. TD was ≥2 transfusion episodes within an 8-week period; responses were transfusion independence (TI) and ≥50% transfusion reduction (minor response). We compared overall survival for non-TD patients receiving lenalidomide versus those not receiving lenalidomide, matched on disease and patient characteristics. We identified 676 patients who had received lenalidomide, including 275 (40.7%) TD and 401 (59.3%) non-TD; 18.5% (125/676) had zero claims for RBC transfusion prior to receiving lenalidomide. Incident toxicities among patients prescribed lenalidomide were similar in TD and non-TD groups, except incident thromboembolic events were higher among non-TD patients (10.8% vs. 6.0%, P = .04). Comparing 191 non-TD patients receiving lenalidomide within 6 months of MDS diagnosis to risk-matched MDS controls, lenalidomide was not associated with improved OS (P = .78). Among TD patients (n = 275), 31% achieved TI, and 30% achieved minor hematologic response, with a median time to TI of 4.1 weeks. In conclusion, we confirmed the benefit of lenalidomide among TD patients with MDS; however, many non-TD patients also received lenalidomide. These patients experienced accompanying toxicity without evidence of benefit in terms of transfusion needs or overall survival.

Genomic correlates of response to immune checkpoint blockade in microsatellite-stable solid tumors

Tumor mutational burden correlates with response to immune checkpoint blockade in multiple solid tumors, although in microsatellite-stable tumors this association is of uncertain clinical utility. Here we uniformly analyzed whole-exome sequencing (WES) of 249 tumors and matched normal tissue from patients with clinically annotated outcomes to immune checkpoint therapy, including radiographic response, across multiple cancer types to examine additional tumor genomic features that contribute to selective response. Our analyses identified genomic correlates of response beyond mutational burden, including somatic events in individual driver genes, certain global mutational signatures, and specific HLA-restricted neoantigens. However, these features were often interrelated, highlighting the complexity of identifying genetic driver events that generate an immunoresponsive tumor environment. This study lays a path forward in analyzing large clinical cohorts in an integrated and multifaceted manner to enhance the ability to discover clinically meaningful predictive features of response to immune checkpoint blockade.

Microsatellite Instability: A Predictive Biomarker for Cancer Immunotherapy

Immunotherapy has shown promising results in various types of cancers. Checkpoint inhibitor drugs developed for cancer immunotherapy have been approved by the US Food and Drug Administration (FDA) for patients with advanced melanoma, non-small cell lung cancer, renal cell carcinoma, bladder cancers, and refractory Hodgkin lymphoma. In the latest announcement, the FDA has granted accelerated approval to pembrolizumab for pediatric and adult patients with microsatellite instability-high (MSI-H) or mismatch repair-deficient solid tumors. This is the first time the agency has approved a cancer treatment based on a common biomarker rather than organ-based approach. MSI-H, either due to inherited germline mutations of mismatch repair genes or epigenetic inactivation of these genes, is found in a subset of colorectal and noncolorectal carcinomas. It is known that MSI-H causes a build up of somatic mutations in tumor cells and leads to a spectrum of molecular and biological changes including high tumor mutational burden, increased expression of neoantigens and abundant tumor-infiltrating lymphocytes. These changes have been linked to increased sensitivity to checkpoint inhibitor drugs. In this mini review, we provide an update on MSI-related solid tumors with special focus on the predictive role of MSI for checkpoint immunotherapy.

Checkpoint blockade-based immunotherapy in the context of tumor microenvironment: Opportunities and challenges

A dynamic and mutualistic interaction between tumor cells and tumor microenvironment (TME) promotes the progression and metastasis of solid tumors. Cancer immunotherapy is becoming a major treatment paradigm for a variety of cancers. Although immunotherapy, especially the use of immune checkpoint inhibitors, has achieved clinical success, only a minority of patients exhibits durable responses. Clinical studies directed at identifying appropriate biomarkers and immune profiles that can be used to predict immunotherapy responses are presently being conducted. Combining treatment strategies tailored to cancer-immune interactions are designed to increase the rate of durable clinical response in patients. It is essential to establish a reasonable tumor classification strategy according to TME to improve cancer immunotherapy. In the current review, a modified classification of TME is proposed, and optimization of TME classification is needed through detailed and integrated molecular characterization of large patient cohorts in the future.

Constrained Combinatorial Libraries of Gp2 Proteins Enhance Discovery of PD-L1 Binders

Engineered protein ligands are used for molecular therapy, diagnostics, and industrial biotechnology. The Gp2 domain is a 45-amino acid scaffold that has been evolved for specific, high-affinity binding to multiple targets by diversification of two solvent-exposed loops. Inspired by sitewise enrichment of select amino acids, including cysteine pairs, in earlier Gp2 discovery campaigns, we hypothesized that the breadth and efficiency of de novo Gp2 discovery will be aided by sitewise amino acid constraint within combinatorial library design. We systematically constructed eight libraries and comparatively evaluated their efficacy for binder discovery via yeast display against a panel of targets. Conservation of a cysteine pair at the termini of the first diversified paratope loop increased binder discovery 16-fold ( p < 0.001). Yet two other libraries with conserved cysteine pairs, within the second loop or an interloop pair, did not aid discovery thereby indicating site-specific impact. Via a yeast display protease resistance assay, Gp2 variants from the loop one cysteine pair library were 3.3 ± 2.1-fold ( p = 0.005) more stable than nonconstrained variants. Sitewise constraint of noncysteine residues-guided by previously evolved binders, natural Gp2 homology, computed stability, and structural analysis-did not aid discovery. A panel of binders to programmed death ligand 1 (PD-L1), a key target in cancer immunotherapy, were discovered from the loop 1 cysteine constraint library. Affinity maturation via loop walking resulted in strong, specific cellular PD-L1 affinity ( K_d = 6-9 nM).

A versatile T cell-based assay to assess therapeutic antigen-specific PD-1-targeted approaches

Blockade of programmed cell death protein 1 (PD-1) immune checkpoint receptor signaling is an established standard treatment for many types of cancer and indications are expanding. Successful clinical trials using monoclonal antibodies targeting PD-1 signaling have boosted preclinical research, encouraging development of novel therapeutics. Standardized assays to evaluate their bioactivity, however, remain restricted. The robust bioassays available all lack antigen-specificity. Here, we developed an antigen-specific, short-term and high-throughput T cell assay with versatile readout possibilities. A genetically modified T cell receptor (TCR)-deficient T cell line was stably transduced with PD-1. Transfection with messenger RNA encoding a TCR of interest and subsequent overnight stimulation with antigen-presenting cells, results in eGFP-positive and granzyme B-producing T cells for single cell or bulk analysis. Control antigen-presenting cells induced reproducible high antigen-specific eGFP and granzyme B expression. Upon PD-1 interaction, ligand-positive antigen-presenting immune or tumor cells elicited significantly lower eGFP and granzyme B expression, which could be restored by anti-PD-(L)1 blocking antibodies. This convenient cell-based assay shows a valuable tool for translational and clinical research on antigen-specific checkpoint-targeted therapy approaches.

PD-L1 is expressed on human platelets and is affected by immune checkpoint therapy

Cancer immunotherapy has been revolutionised by drugs that enhance the ability of the immune system to detect and fight tumors. Immune checkpoint therapies that target the programmed death-1 receptor (PD-1), or its ligand (PD-L1) have shown unprecedented rates of durable clinical responses in patients with various cancer types. However, there is still a large fraction of patients that do not respond to checkpoint inhibitors, and the challenge remains to find cellular and molecular cues that could predict which patients would benefit from these therapies. Using a series of qualitative and quantitative methods we show here that PBMCs and platelets from smokers and patients with head and neck squamous cell carcinoma (HNSCC) or lung cancer express and up-regulate PD-L1 independently of tumor stage. Furthermore, treatment with Atezolizumab, a fully humanised monoclonal antibody against PD-L1, in 4 patients with lung cancer caused a decrease in PD-L1 expression in platelets, which was restored over 20 days. Altogether, our findings reveal the expression of the main therapeutic target in current checkpoint therapies in human platelets and highlight their potential as biomarkers to predict successful therapeutic outcomes.