Rationale for combination of therapeutic antibodies targeting tumor cells and immune checkpoint receptors: Harnessing innate and adaptive immunity through IgG1 isotype immune effector stimulation

Immunotherapy in gastrointestinal cancer: The current scenario and future perspectives

Gastrointestinal cancers include colorectal, gastric, oesophageal, pancreatic and liver cancers. They continue to be a significant cause of mortality and morbidity worldwide. Current treatment strategies include chemotherapy, surgery, radiotherapy and targeted therapies. Immunotherapy has recently been incorporated in treatment regimens for some gastrointestinal malignancies and research into different immune modifying treatments is being carried out in this context. Approaches to immune modulation such as vaccination, adoptive cell therapy and checkpoint inhibition have shown varying clinical benefit, with most of the benefit seen in checkpoint inhibition. This review summarises recent advances and future direction of immunotherapy in patients with gastrointestinal malignancies.

The Potential of CD16 on Plasma-Derived Exosomes as a Liquid Biomarker in Head and Neck Cancer

Head and neck squamous cell carcinomas (HNSCC) are highly immune suppressive and aggressive malignancies. As part of the tumor microenvironment, exosomes contribute to this immune suppression. The Fc receptor CD16 is widely expressed on monocytes, neutrophils, and natural killer (NK) cells and is involved in antibody-dependent cell-mediated cytotoxicity (ADCC). Here, surface levels of CD16 on total exosomes and tumor-derived exosomes (TEX) from plasma of HNSCC patients were analyzed regarding their potential as liquid biomarkers for disease stage. Exosomes were isolated from plasma using mini size exclusion chromatography. TEX were enriched by immune affinity capture with CD44v3 antibodies. On-bead flow cytometry was used to measure CD16 levels on total exosomes and TEX. The results were correlated with clinicopathological parameters. Total exosomes from HNSCC patients had significantly higher CD16 levels compared to TEX. Further, CD16 surface levels of total exosomes, but not TEX, correlated with clinicopathological parameters. Patients with advanced tumor stages T3/4 and Union for International Cancer Control (UICC) stages III/IV had significantly higher CD16 levels on total exosomes compared to patients with early tumor stages T1/2 and UICC stages I/II, respectively. Overall, CD16 positive exosomes have the potential as liquid biomarkers for HNSCC tumor stage and aggressiveness.

Resistance to anti-epidermal growth factor receptor in metastatic colorectal cancer: What does still need to be addressed?

Colorectal cancer (CRC) represents a global health problem, being one of the most diagnosed and aggressive tumors. Cetuximab and panitumumab monoclonal antibodies (mAbs) in combination with chemotherapy are an effective strategy for patients with RAS Wild Type (WT) metastatic colorectal cancer (mCRC). However, tumors are often unresponsive or develop resistance. In the last years, molecular alterations in principal oncogenes (RAS, BRAF, PI3KCA, PTEN) in the downstream pathway of the epidermal growth factor receptor (EGFR) and in other receptors (HER2, MET) that converge on MAPK-ERK signalling have been identified as novel mechanisms of resistance to anti-EGFR strategies. However, further efforts are needed to better stratify CRCs and ensure more individualized treatments. Herein, we describe the consolidated molecular drivers of resistance and the therapeutic strategies available so far, with an overview on potential biomarkers of response that could be integrated in clinical practice.

Efficacy and safety of necitumumab and pembrolizumab combination therapy in patients with Stage IV non-small cell lung cancer

OBJECTIVES

Efficacy and safety of necitumumab when combined with pembrolizumab was assessed in patients with Stage IV non-small cell lung cancer (NSCLC) of squamous and nonsquamous histology, who had progressed after treatment with a platinum-based doublet.

MATERIALS AND METHODS

This single-arm, multicenter, phase Ib study had a dose-finding phase, in which escalating doses of necitumumab (600 mg and 800 mg IV) were administered on Day 1 and 8 every 3 weeks (Q3W) in combination with pembrolizumab (200 mg IV) on Day 1 Q3W, and expansion cohorts. Patients were treated until progressive disease (PD), toxicity requiring cessation, protocol noncompliance, or withdrawal of consent. Efficacy was evaluated by overall response rate (ORR).

RESULTS

In 64 treated patients (32 patients [50 %] were programmed death-ligand 1 [PD-L1] negative), confirmed ORR was 23.4 % (95 % confidence interval [CI] 13.8 %-35.7 %). Two patients (3.1 %) had complete response (CR), 13 patients (20.3 %) had partial response (PR), 26 patients (40.6 %) had stable disease, 17 patients (26.6 %) had PD, and 6 patients (9.4 %) were not evaluable. Regardless of histology or PD-L1 status, median PFS (mPFS) was 4.1 months (95 % CI 2.4-6.9 months) and OS at 6 months was 74.7 % (61.5%-83.9%). Confirmed disease control rate was 64.1 % (95 % CI 51.5-75.7). Patients with programmed death-ligand 1 (PD-L1) ≥1% had numerically improved ORR and median progression-free survival when compared with patients with PD-L1 negative cancer. No dose-limiting toxicities were recorded and the combination of necitumumab 800 mg with pembrolizumab 200 mg was considered tolerable.

CONCLUSION

Results suggest modest benefits of second-line necitumumab and pembrolizumab combination therapy in patients with Stage IV NSCLC. Safety profiles were consistent with class effects typical of epidermal growth factor receptor inhibitors and immunotherapies with no additive toxicities.

NK Cell-Based Immune Checkpoint Inhibition

Immunotherapy, with an increasing number of therapeutic dimensions, is becoming an important mode of treatment for cancer patients. The inhibition of immune checkpoints, which are the source of immune escape for various cancers, is one such immunotherapeutic dimension. It has mainly been aimed at T cells in the past, but NK cells are a newly emerging target. Simultaneously, the number of checkpoints identified has been increasing in recent times. In addition to the classical NK cell receptors KIRs, LIRs, and NKG2A, several other immune checkpoints have also been shown to cause dysfunction of NK cells in various cancers and chronic infections. These checkpoints include the revolutionized CTLA-4, PD-1, and recently identified B7-H3, as well as LAG-3, TIGIT & CD96, TIM-3, and the most recently acknowledged checkpoint-members of the Siglecs family (Siglec-7/9), CD200 and CD47. An interesting dimension of immune checkpoints is their candidacy for dual-checkpoint inhibition, resulting in therapeutic synergism. Furthermore, the combination of immune checkpoint inhibition with other NK cell cytotoxicity restoration strategies could also strengthen its efficacy as an antitumor therapy. Here, we have undertaken a comprehensive review of the literature to date regarding NK cell-based immune checkpoints.

VITAL phase 2 study: Upfront 5-fluorouracil, mitomycin-C, panitumumab and radiotherapy treatment in nonmetastatic squamous cell carcinomas of the anal canal (GEMCAD 09-02)

Aim

VITAL, a phase II single‐arm study, aimed to evaluate efficacy and safety of panitumumab addition to 5‐fluorouracil (5‐FU), mitomycin‐C (MMC) and radiotherapy (RT) in patients with localized squamous cell carcinoma of the anal canal (SCCAC).

Methods

Adult, treatment‐naïve SCCAC patients (Stage T2‐T4, any N, M0) and ECOG‐PS ≤2, received panitumumab (6 mg/kg, day 1 and Q2W; 8 weeks), 5‐FU (1000 mg/m²/d, days 1‐4 and 29‐32), MMC (10 mg/m², days 1 and 29) and RT 45 Gy (1.8 Gy/fraction) to the primary tumor and mesorectal, iliac and inguinal lymph nodes, plus 10‐15 Gy boost dose to the primary tumor and affected lymph nodes. The primary objective was disease free survival rate (DFS) at 3‐years (expected 3‐year DFS rate: 73.7 ± 12%).

Results

Fifty‐eight patients (31 women; median age: 59 years; ECOG‐PS 0‐1:98%; TNM II [29%] (T2 or T3/N0/M0)/IIIA (T1‐T3/N1/M0 or T4/N0/M0) [21%]/IIIB (T4/N1/M0 or any T/N2 or N3/M0) [47%]/nonevaluable [4%]) were included. The median follow‐up was 45 months. The 3‐year DFS rate was 61.1% (95% CI: 47.1, 72.4). The 3‐year overall survival rate was 78.4% (95% CI: 65.1, 87.1). Eighteen patients (31.0%) required a colostomy within 2 years posttreatment. Grade 3‐4 toxicities were experienced by 53 (91%) patients. Most common grade 3‐4 treatment‐related events were radiation skin injury (40%) and neutropenia (24%). No toxic deaths occurred. Improved efficacy in colostomy‐free survival and complete response rate was observed in human papilloma virus positive patients.

Conclusions

Panitumumab addition to MMC‐5FU regimen in SCCAC patients increases toxicity and does not improve patients’ outcomes. RT plus MMC‐5FU remains the standard of care for localized SCCAC patients.

EGFR inhibition for metastasized cutaneous squamous cell carcinoma in dystrophic epidermolysis bullosa

Dystrophic epidermolysis bullosa (DEB) is a hereditary skin fragility disorder, characterized by trauma-induced blistering followed by soft tissue fibrosis. One of the most feared complications is the early development of aggressive cutaneous squamous cell carcinomas (SCC). For patients with locally advanced or metastasized SCCs treatment with cetuximab, a monoclonal antibody against epidermal growth factor receptor (EGFR), has been proposed and so far, treatment of five DEB patients with cetuximab has been published. With this report, we extend the spectrum of EB patients treated with cetuximab by adding two additional patients. Taking together all DEB cases treated with cetuximab, we propose that cetuximab should be administered as early as possible, since it seems to be more efficient and is accompanied by rather mild adverse effects. We also show that EGFR is frequently expressed in DEB-associated SCCs, although there were noticeable differences in the level of expression, which may influence responsiveness to EGFR-targeting therapies. Although only limited experiences with targeted cancer treatments in EB exist, such reports highlight the treatments' effects in this specific cohort and assist our therapeutic decisions.

Targeting the Immune Microenvironment in the Treatment of Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a highly aggressive solid tumor, with a 5-year mortality rate of ~50%. The development of immunotherapies has improved the survival of patients with HNSCC, but, the long-term prognosis of patients with recurrent or metastatic HNSCC remains poor. HNSCC is characterized by intratumoral infiltration of regulatory T cells, dysfunctional natural killer cells, an elevated Treg/CD8+ T cell ratio, and increased programmed cell death ligand 1 protein on tumor cells. This leads to an immunocompromised niche in favor of the proliferation and treatment resistance of cancer cells. To achieve an improved treatment response, several potential combination strategies, such as increasing the neoantigens for antigen presentation and therapeutic agents targeting components of the tumor microenvironment, have been explored and have shown promising results in preclinical studies. In addition, large-scale bioinformatic studies have also identified possible predictive biomarkers of HNSCC. As immunotherapy has shown survival benefits in recent HNSCC clinical trials, a comprehensive investigation of immune cells and immune-related factors/cytokines and the immune profiling of tumor cells during the development of HNSCC may provide more insights into the complex immune microenvironment and thus, facilitate the development of novel immunotherapeutic agents.

Immune checkpoint inhibitors in gastrointestinal malignancies: what can we learn from experience with other tumors?

Gastrointestinal (GI) malignancies are some of the most common cancers worldwide with high rates of morbidity and mortality. Immune checkpoint inhibitors have afforded additional treatment options for patients, but their success has been limited. Conversely, in other tumor types such as lung cancer, melanoma and renal cell carcinoma, treatment strategies with immune checkpoint inhibitors have propelled those agents into the front lines of treatment. Strategies utilized include combining immune checkpoint inhibitors with chemotherapy, other checkpoint inhibitors, and targeted therapy. In this review, we analyze combination strategies employed in other tumor types to help identify current and future approaches toward improving outcomes with immunotherapy in GI malignancies.

Distinguishing Features of Cetuximab and Panitumumab in Colorectal Cancer and Other Solid Tumors

Cetuximab and panitumumab are two distinct monoclonal antibodies (mAbs) targeting the epidermal growth factor receptor (EGFR), and both are widely used in combination with chemotherapy or as monotherapy to treat patients with RAS wild-type metastatic colorectal cancer. Although often considered interchangeable, the two antibodies have different molecular structures and can behave differently in clinically relevant ways. More specifically, as an immunoglobulin (Ig) G1 isotype mAb, cetuximab can elicit immune functions such as antibody-dependent cell-mediated cytotoxicity involving natural killer cells, T-cell recruitment to the tumor, and T-cell priming via dendritic cell maturation. Panitumumab, an IgG2 isotype mAb, does not possess these immune functions. Furthermore, the two antibodies have different binding sites on the EGFR, as evidenced by mutations on the extracellular domain that can confer resistance to one of the two therapeutics or to both. We consider a comparison of the properties of these two antibodies to represent a gap in the literature. We therefore compiled a detailed, evidence-based educational review of the known molecular, clinical, and functional differences between the two antibodies and concluded that they are distinct therapeutic agents that should be considered individually during treatment planning. Available data for one agent can only partly be extrapolated to the other. Looking to the future, the known immune activity of cetuximab may provide a rationale for this antibody as a combination partner with investigational chemotherapy plus immunotherapy regimens for colorectal cancer.

Population Pharmacokinetic Analysis of Bintrafusp Alfa in Different Cancer Types

INTRODUCTION

Bintrafusp alfa, an innovative first-in-class bifunctional fusion protein composed of the extracellular domain of the TGF-βRII receptor (a TGF-β "trap") fused to a human IgG1 monoclonal antibody blocking programmed death ligand 1, has shown promising antitumor activity and manageable safety.

METHODS

To support the dosing strategy for bintrafusp alfa, we developed a population pharmacokinetics model using a full covariate modeling approach, based on pharmacokinetic and covariate data from 644 patients with various solid tumors who received bintrafusp alfa intravenously in two clinical studies.

RESULTS

A two-compartmental linear model best described bintrafusp alfa concentrations, and no time-varying clearance was identified. Using this model, the estimated clearance was 0.0158 l/h (relative standard error, 4.1%), and the central and peripheral volume of distribution were 3.21 l (relative standard error, 3.2%) and 0.483 l (relative standard error, 9.8%), respectively. The estimated mean elimination half-life of bintrafusp alfa was 6.93 days (95% CI 4.69-9.65 days). Several intrinsic factors (bodyweight, albumin, sex, and tumor type) were found to influence bintrafusp alfa pharmacokinetics, but none of these covariate effects was considered clinically meaningful and no dosage adjustments are recommended. Notably, simulations from the model suggested less variability in exposure metrics with flat dosing versus weight-based dosing.

CONCLUSIONS

Pharmacokinetic analysis of bintrafusp alfa supports the use of a flat dose regimen in further clinical trials (recommended phase 2 dose: 1200 mg every 2 weeks).

TRIAL REGISTRATION

ClinicalTrials.gov identifiers: NCT02517398 and NCT02699515.

FUNDING

Merck Healthcare KGaA as part of an alliance between Merck Healthcare KGaA and GlaxoSmithKline.

The Evolving Role of Taxanes in Combination With Cetuximab for the Treatment of Recurrent and/or Metastatic Squamous Cell Carcinoma of the Head and Neck: Evidence, Advantages, and Future Directions

The addition of cetuximab to platinum-based chemotherapy (cisplatin or carboplatin plus 5-fluorouracil [5-FU]), followed by maintenance cetuximab until disease progression (EXTREME), resulted in the first regimen to yield significantly improved survival outcomes in the first-line treatment of patients with recurrent and/or metastatic squamous cell carcinoma of the head and neck (R/M SCCHN) in over 30 years. Currently, the EXTREME regimen is a guideline-recommended treatment in the first-line R/M setting, and, therefore, it is used as a control arm in all new first-line, phase 3 immunotherapy trials. More recently, new checkpoint inhibitor approaches have emerged and are changing the treatment landscape for PD-L1-positive patients with R/M SCCHN. Additionally, alternative chemotherapy backbones in R/M SCCHN are continually investigated. Replacing 5-FU with a taxane in the EXTREME regimen seeks to take advantage of the potential immunogenic and proapoptotic synergy between cetuximab and docetaxel or paclitaxel. These cetuximab-, platinum-, and taxane-based treatments have demonstrated promising survival results and cytoreductive properties in single-arm studies. Thus, these combination treatments may be of importance to patients with high tumor burden and dangerous site involvements (e.g., causing bleeding, suffocation, dysphagia, or ulceration), in whom symptom relief is a key treatment goal. TPExtreme is the first large, randomized trial comparing a cetuximab, platinum, and taxane combination regimen with EXTREME. Currently, the substitution of 5-FU with a taxane is a feasible and clinically beneficial option for patients with contraindications to 5-FU. The TPEx regimen appears to be a new option in first-line R/M SCCHN, with a shorter time on CT and significantly lower toxicity than the EXTREME regimen. For patients with R/M disease in whom further cisplatin- or carboplatin-based treatment is unsuitable, or whose disease has already progressed on first-line R/M therapy, treatment options such as cetuximab plus a taxane, which capitalize on the combinative ability of the 2 agents, can be considered. Notably, it is as of yet unknown what second-line treatments may be suitable to follow a checkpoint inhibitor-based first-line therapy.

PD-1/PD-L1 blockade in paediatric cancers: What does the future hold?

Checkpoint blockade (CPB) immunotherapy has shown unprecedented success in a wide range of adult malignancies, and is increasingly being employed in the treatment of advanced cancers. However, the experience in the paediatric population remains limited and the small number of single agent studies reported have shown disappointing response rates. Paediatric cancers offer unique challenges that can hinder the translation of CPB into the paediatric clinic, and combinational therapies are likely to be needed to achieve therapeutic success. As the number of paediatric trials using CPB rapidly increases, understanding the challenges that these agents may encounter in this population is of special significance to allow the design of optimal combinatorial strategies for each tumour type. Here, we offer an overview of the unique biological and immunological features of paediatric cancers as compared to adult malignancies, and how these might impact the overall success of CPB in the paediatric population. We review the growing body of pre-clinical and clinical experiences to date, and discuss future strategies involving the combination of CPB with traditionally used therapies (chemotherapy and radiotherapy) or with other newly developed immunotherapies.

Nivolumab in Patients with Recurrent or Metastatic Squamous Cell Carcinoma of the Head and Neck: Efficacy and Safety in CheckMate 141 by Prior Cetuximab Use

PURPOSE

Cetuximab, which modulates immune responses, may affect the efficacy of subsequent immunotherapy. Here, we assessed outcomes with nivolumab, by prior cetuximab exposure, in patients with recurrent or metastatic (R/M) squamous cell carcinoma of the head and neck (SCCHN) who had experienced progression within 6 months of platinum-containing chemotherapy.

PATIENTS AND METHODS

In the randomized, open-label, phase III CheckMate 141 trial, patients were randomized 2:1 to nivolumab 3 mg/kg every 2 weeks or investigator's choice (IC) of single-agent chemotherapy, with stratification by prior cetuximab exposure. The primary endpoint was overall survival (OS); additional endpoints were progression-free survival, objective response rate, and safety.

RESULTS

In patients with prior cetuximab exposure, the median OS was 7.1 months with nivolumab versus 5.1 months with IC (HR, 0.84; 95% CI, 0.62-1.15); OS benefit with nivolumab was maintained across most demographic subgroups. In patients without prior cetuximab exposure, the median OS was 8.2 months with nivolumab versus 4.9 months with IC (HR, 0.52; 95% CI, 0.35-0.77); OS benefit with nivolumab was maintained across patient baseline subgroups including tumor programmed death ligand 1 (PD-L1) expression (<1% or ≥1%). Grade 3-4 treatment-related adverse event rates favored nivolumab versus IC in both subgroups.

CONCLUSIONS

Nivolumab appeared to improve efficacy versus IC regardless of prior cetuximab use, supporting its use in patients with R/M SCCHN with or without prior cetuximab exposure. The reduction in risk of death with nivolumab compared with IC was greater in patients without prior cetuximab exposure versus with prior cetuximab exposure.

Combinatorial Approaches With Checkpoint Inhibitors to Enhance Anti-tumor Immunity

Treatment of cancer patients has been recently revolutionized by the application of various immunotherapeutics. However, the response rates are still limited ranging between approximately 20 and 40% suggesting that combinations of immunotherapy with conventional treatment, like chemotherapy, radiation, epigenetic modulators, targeted therapies using small molecules as well as other (immuno) therapeutics, might be an option to increase systemic anti-tumor immunity. It is postulated that different non-immune based therapies in combination with immunotherapies could reprogram the immune suppressive tumor microenvironment and enhance the immunogenicity of tumor cells leading to an improved therapeutic efficacy and a better patients' outcome. Despite there exist various examples of increased objective responses achieved by adding these different therapies to immunotherapies, strategies for rational and evidence-based design of checkpoint inhibitor combinations to maximize the clinical benefit for patients are urgently required. Therefore, the main purpose of this review is to summarize recent results obtained from experimental models and clinical trials to enhance tumor immunogenicity by combining immunotherapy with other therapeutic options to maximize patients' outcome and minimize adverse events.

Targeted Therapies and Immune-Checkpoint Inhibition in Head and Neck Squamous Cell Carcinoma: Where Do We Stand Today and Where to Go?

With an increased understanding of the tumor biology of squamous cell carcinoma of the head and neck (SCCHN), targeted therapies have found their way into the clinical treatment routines against this entity. Nevertheless, to date platinum-based cytostatic agents remain the first line choice and targeting the epidermal growth factor-receptor (EGFR) with combined cetuximab and radiation therapy remains the only targeted therapy approved in the curative setting. Investigation of immune checkpoint inhibitors (ICI), such as antibodies targeting programmed cell death protein 1 (PD-1) and its ligand PD-L1, resulted in a change of paradigms in oncology and in the first approval of new drugs for treating SCCHN. Nivolumab and pembrolizumab, two anti-PD-1 antibodies, were the first agents shown to improve overall survival for patients with metastatic/recurrent tumors in recent years. Currently, several clinical trials investigate the role of ICI in different therapeutic settings. A robust set of biomarkers will be an inevitable tool for future individualized treatment approaches including radiation dose de-escalation and escalation strategies. This review aims to summarize achieved goals, the current status and future perspectives regarding targeted therapies and ICI in the management of SCCHN.

NK-mediated antibody-dependent cell-mediated cytotoxicity in solid tumors: biological evidence and clinical perspectives

The process of antibody-dependent cell-mediated cytotoxicity (ADCC) makes use of the innate immune cells providing antitumor cytotoxicity activated by antibodies linked to target cells. Natural killer (NK) cells are a small set of lymphocytes, but are considered the most important cells among those able to induce ADCC. They provoke innate immune responses and harmonise spontaneous cytotoxicity towards tumor and virus-infected cells. They are able to swiftly produce biochemical signals and cytokines so as to stimulate subsequent adaptive immune responses. Immunotherapeutics that target NK cells, augmenting their immune response, can cause the antitumor dynamics of the antibodies to be improved. The recent developments in the field of NK cell immunotherapy and genotypic factors which might affect patient responses to antibody-dependent immunotherapies are the main subject of this review, with a particular focus on the manipulations and strategies used to augment ADCC. In the next years combined treatment with monoclonal antibodies (mAbs) and immunomodulatory drugs will be an important part in antitumor therapy. The main challenge remains the difficulty in distinguishing in the clinical setting, between the target effect that many mAbs exert against specific cell membrane receptors and the ADCC effect that they too also can induce. Drugs able to activate NK cells, that are major actors in mAb-mediated ADCC, will improve the ADCC effect against tumors.

Immune Modulation of Head and Neck Squamous Cell Carcinoma and the Tumor Microenvironment by Conventional Therapeutics

Head and neck squamous cell carcinoma (HNSCC) accounts for more than 600,000 cases and 380,000 deaths annually worldwide. Although human papillomavirus (HPV)-associated HNSCCs have better overall survival compared with HPV-negative HNSCC, loco-regional recurrence remains a significant cause of mortality and additional combinatorial strategies are needed to improve outcomes. The primary conventional therapies to treat HNSCC are surgery, radiation, and chemotherapies; however, multiple other targeted systemic options are used and being tested including cetuximab, bevacizumab, mTOR inhibitors, and metformin. In 2016, the first checkpoint blockade immunotherapy was approved for recurrent or metastatic HNSCC refractory to platinum-based chemotherapy. This immunotherapy approval confirmed the critical importance of the immune system and immunomodulation in HNSCC pathogenesis, response to treatment, and disease control. However, although immuno-oncology agents are rapidly expanding, the role that the immune system plays in the mechanism of action and clinical efficacy of standard conventional therapies is likely underappreciated. In this article, we focus on how conventional and targeted therapies may directly modulate the immune system and the tumor microenvironment to better understand the effects and combinatorial potential of these therapies in the context and era of immunotherapy.

Immunotherapy-based combination strategies for treatment of gastrointestinal cancers: current status and future prospects

Strategies in comprehensive therapy for gastrointestinal (GI) cancer have been optimized in the last decades to improve patients' outcomes. However, treatment options remain limited for late-stage or refractory diseases. The efficacy of immune checkpoint inhibitors (ICIs) for treatment of refractory GI cancer has been confirmed by randomized clinical trials. In 2017, pembrolizumab was approved by the US Food and Drug Administration as the first agent for treatment of metastatic solid tumors with mismatch repair deficiency, especially for colorectal cancer. Given the different mechanisms, oncologists have focused on determining whether ICIs-based combination strategies could achieve higher efficacy than conventional therapy alone in late-stage or even front-line treatment of GI cancer. This review discusses the current status of combining immune checkpoint inhibitors with molecular targeted therapy, chemotherapy, or radiotherapy in GI cancer in terms of mechanisms, safety, and efficacy to provide basis for future research.

Combination of KIR2DS4 and FcγRIIa polymorphisms predicts the response to cetuximab in KRAS mutant metastatic colorectal cancer

Cetuximab is a standard-of-care treatment for RAS wild-type metastatic colorectal cancer (mCRC) but not for those harbor a KRAS mutation since MAPK pathway is constitutively activated. Nevertheless, cetuximab also exerts its effect by its immunomodulatory activity despite the presence of RAS mutation. The aim of this study was to determine the impact of polymorphism FcγRIIIa V158F and killer immunoglobulin-like receptor (KIR) genes on the outcome of mCRC patients with KRAS mutations treated with cetuximab. This multicenter Phase II clinical trial included 70 mCRC patients with KRAS mutated. We found KIR2DS4 gene was significantly associated with OS (HR 2.27; 95% CI, 1.08–4.77; P = 0.03). In non-functional receptor homozygotes the median OS was 2.6 months longer than in carriers of one copy of full receptor. Multivariate analysis confirmed KIR2DS4 as a favorable prognostic marker for OS (HR 6.71) in mCRC patients with KRAS mutation treated with cetuximab. These data support the potential therapeutic of cetuximab in KRAS mutated mCRC carrying non-functional receptor KIR2DS4 since these patients significantly prolong their OS even after heavily treatment. KIR2DS4 typing could be used as predictive marker for identifying RAS mutated patients that could benefit from combination approaches of anti-EGFR monoclonal antibodies and other immunotherapies to overcome the resistance mediated by mutation in RAS.

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.

Mutated Von Hippel-Lindau-renal cell carcinoma (RCC) promotes patients specific natural killer (NK) cytotoxicity

Background

Previous evidence demonstrated that restoration of wild type VHL in human renal cancer cells decreased in vitro NK susceptibility. To investigate on the role of tumoral VHL status versus NK capability in renal cancer patients, 51 RCC patients were characterized for VHL mutational status and NK function.

Methods

VHL mutational status was determined by direct DNA sequencing on tumor tissue. NK cytotoxicity was measured against specific target cells K562, VHL-wild type (CAKI-1) and VHL-mutated (A498) human renal cancer cells through externalization of CD107a and IFN-γ production. Activating NK receptors, NKp30, NKp44, NKp46, NKG2D, DNAM-1, NCAM-1 and FcγRIIIa were evaluated through quantitative RT-PCR. RCC tumoral Tregs were characterized as CD4⁺CD25⁺CD127^lowFoxp3⁺ and Treg function was evaluated as inhibition of T-effector proliferation.

Results

VHL mutations were detected in 26/55 (47%) RCC patients. IL-2 activated whole-blood samples (28 VHL-WT-RCC and 23 VHL-MUT-RCC) were evaluated for NK cytotoxicity toward human renal cancer cells A498, VHL-MUT and CAKI-1, VHL-WT. Efficient NK degranulation and increase in IFN-γ production was detected when IL-2 activated whole-blood from VHL-MUT-RCC patients were tested toward A498 as compared to CAKI-1 cells (CD107a⁺NK: 7 ± 2% vs 1 ± 0.41%, p = 0.015; IFN-γ⁺NK: 6.26 ± 3.4% vs 1.78 ± 0.9% respectively). In addition, IL-2 activated NKs induced higher CD107a exposure in the presence of RCC autologous tumor cells or A498 as compared to SN12C (average CD107a⁺NK: 4.7 and 2.7% vs 0.3% respectively at 10E:1 T ratio).

VHL-MUT-RCC tumors were NKp46⁺ cells infiltrated and expressed high NKp30 and NKp46 receptors as compared to VHL-WT-RCC tumors. A significant lower number of Tregs was detected in the tumor microenvironment of 13 VHL-MUT-RCC as compared to 13 VHL-WT-RCC tumors (1.84 ± 0.36% vs 3.79 ± 0.74% respectively, p = 0.04). Tregs isolated from VHL-MUT-RCC patients were less suppressive of patients T effector proliferation compared to Tregs from VHL-WT-RCC patients (Teff proliferation: 6.7 ± 3.9% vs 2.8 ± 1.1%).

Conclusions

VHL tumoral mutations improve NKs effectiveness in RCC patients and need to be considered in the evaluation of immune response. Moreover therapeutic strategies designed to target NK cells could be beneficial in VHL-mutated-RCCs alone or in association with immune checkpoints inhibitors.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0952-7) contains supplementary material, which is available to authorized users.

Anti-NKG2A mAb Is a Checkpoint Inhibitor that Promotes Anti-tumor Immunity by Unleashing Both T and NK Cells

Checkpoint inhibitors have revolutionized cancer treatment. However, only a minority of patients respond to these immunotherapies. Here, we report that blocking the inhibitory NKG2A receptor enhances tumor immunity by promoting both natural killer (NK) and CD8⁺ T cell effector functions in mice and humans. Monalizumab, a humanized anti-NKG2A antibody, enhanced NK cell activity against various tumor cells and rescued CD8⁺ T cell function in combination with PD-x axis blockade. Monalizumab also stimulated NK cell activity against antibody-coated target cells. Interim results of a phase II trial of monalizumab plus cetuximab in previously treated squamous cell carcinoma of the head and neck showed a 31% objective response rate. Most common adverse events were fatigue (17%), pyrexia (13%), and headache (10%). NKG2A targeting with monalizumab is thus a novel checkpoint inhibitory mechanism promoting anti-tumor immunity by enhancing the activity of both T and NK cells, which may complement first-generation immunotherapies against cancer.

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Blocking NKG2A unleashes both T and NK cell effector functions

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Combined blocking of the NKG2A and the PD-1 axis promotes anti-tumor immunity

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Blocking NKG2A and triggering CD16 illustrates the efficacy of dual checkpoint therapy

Breast Cancer Chemo-immunotherapy through Liposomal Delivery of an Immunogenic Cell Death Stimulus Plus Interference in the IDO-1 Pathway

Immunotherapy provides the best approach to reduce the high mortality of metastatic breast cancer (BC). We demonstrate a chemo-immunotherapy approach, which utilizes a liposomal carrier to simultaneously trigger immunogenic cell death (ICD) as well as interfere in the regionally overexpressed immunosuppressive effect of indoleamine 2,3-dioxygenase (IDO-1) at the BC tumor site. The liposome was constructed by self-assembly of a phospholipid-conjugated prodrug, indoximod (IND), which inhibits the IDO-1 pathway, followed by the remote loading of the ICD-inducing chemo drug, doxorubicin (DOX). Intravenous injection of the encapsulated two-drug combination dramatically improved the pharmacokinetics and tumor drug concentrations of DOX and IND in an orthotopic 4T1 tumor model in syngeneic mice. Delivery of a threshold ICD stimulus resulted in the uptake of dying BC cells by dendritic cells, tumor antigen presentation and the activation/recruitment of naı̈ve T-cells. The subsequent activation of perforin- and IFN-γ releasing cytotoxic T-cells induced robust tumor cell killing at the primary as well as metastatic tumor sites. Immune phenotyping of the tumor tissues confirmed the recruitment of CD8⁺ cytotoxic T lymphocytes (CTLs), disappearance of Tregs, and an increase in CD8⁺/FOXP3⁺ T-cell ratios. Not only does the DOX/IND-Liposome provide a synergistic antitumor response that is superior to a DOX-only liposome, but it also demonstrated that the carrier could be effectively combined with PD-1 blocking antibodies to eradicate lung metastases. All considered, an innovative nano-enabled approach has been established to allow deliberate use of ICD to switch an immune deplete to an immune replete BC microenvironment, allowing further boosting of the response by coadministered IDO inhibitors or immune checkpoint blocking antibodies.

Crosstalk Between PD-1/PD-L1 Blockade and Its Combinatorial Therapies in Tumor Immune Microenvironment: A Focus on HNSCC

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignancy worldwide with a poor prognosis and high mortality. More than two-thirds of HNSCC patients still have no effective control of clinical progression, and the five-year survival rate is < 50%. Moreover, patients with platinum-refractory HNSCC have a median survival of < 6 months. The significant toxicity and low survival rates of current treatment strategies highlight the necessity for new treatment modalities. Recently, a large number of studies have demonstrated that programmed cell death protein-1 (PD-1) and its ligand, programmed cell death protein ligand-1 (PD-L1) play an essential role in tumor initiation and progression. PD-1/PD-L1 blockade has shown a desired and long-lasting therapeutic effect in the treatment of HNSCC and other malignancies. However, only a small number of patients with HNSCC can benefit from PD-1/PD-L1 blockade monotherapy, while the majority of patients do not respond. To overcome the unsatisfactory therapeutic effect of PD-1/PD-L1 blockade monotherapy, combining other treatment options for HNSCC (including chemotherapy, radiotherapy, targeted therapy, and immunotherapy) in the treatment scheme has become a commonly used strategy. Herein, the potential mechanisms underlying the crosstalk between PD-1/PD-L1 blockade and its combinatorial therapies for HNSCC were reviewed, and it is hoped that the improved understanding of the crosstalk process would provide further ideas for the design of a combinatorial regimen with a higher efficiency and response rate for the treatment of HNSCC and other malignancies.

Window Studies in Squamous Cell Carcinoma of the Head and Neck: Values and Limits

OPINION STATEMENT

In head and neck cancer, we continue to work towards a more personalized approach to treatment of patients, where analysis of a patient's tumor guides targeting of molecular or immunologic pathways. Critically important to this pursuit is a better understanding of the direct biologic effect of a drug or combination on the tumor microenvironment in humans, as well as biomarker discovery. These goals are consistent with the primary purpose of a "window of opportunity" trial and while conduct of these trials requires a careful balance of benefits and potential risks, to date these trials have been both feasible and safe in HNSCC in the curative intent setting. In the era of immunotherapy, with countless possible combinations and ongoing clinical trials, window trials are even more important for informing clinical trial design and appropriate combination therapy, and ultimately a more personalized approach to our patients that leads to improvement in outcomes.

Bone marrow infiltrated Lnc-INSR induced suppressive immune microenvironment in pediatric acute lymphoblastic leukemia

Immune escape due to immunosuppressive microenvironments, such as those associated with regulatory T (Treg) cells is highly associated with initial occurrence and development of solid tumors or hematologic malignancies. Here, we employed high-throughput transcriptome screening to demonstrate immunosuppression-associated increases in the long noncoding (lnc) RNA lnc-insulin receptor precursor (INSR), which was corrected with INSR expression in CD4+ T cells extracted from the bone marrow of patients with childhood acute T lymphoblastic leukemia. Loss-of-function and gain-of-function assays in vitro and in vivo revealed that membrane-localized and cytoplasm-localized lnc-INSR promoted Treg distribution and decreased the percentage of cytotoxic T lymphocytes, which induced tumor growth. Through direct binding with INSR, lnc-INSR blocked the INSR ubiquitination site, causing abnormal activation of INSR and the phosphatidylinositide 3-kinase/AKT-signaling pathway. These results indicated that lnc-INSR might promote immune suppression by enhancing Treg-cell differentiation and serve as valuable therapeutic targets in the immunosuppressive tumor microenvironment.

Somatic mutation-associated T follicular helper cell elevation in lung adenocarcinoma

T follicular helper cells (Tfh) play crucial roles in the development of humoral immunity. In the B cell-rich germinal center of lymphoid organs, they select for high-affinity B cells and aid in their maturation. While Tfh have known roles in B cell malignancies and have prognostic value in some epithelial cancers, their role in lung tumour initiation and development is unknown. Through immune cell deconvolution, we observed significantly increased Tfh in tumours from two independent cohorts of lung adenocarcinomas and found that this upregulation occurs early in tumour development. A subset of tumours were stained for T and B cells using multicolour immunohistochemistry, which revealed the presence of tumour-adjacent tertiary lymphoid organs in 17/20 cases each with an average of 16 Tfh observed in the germinal center. Importantly, Tfh levels were correlated with tumour mutational load and immunogenic cancer testis antigens, suggesting their involvement in mounting an active immune response against tumour neoantigens.

The Relationship Between Tumor Glucose Metabolism and Host Systemic Inflammatory Responses in Patients with Cancer: A Systematic Review

One of the most important and long recognized characteristics of tumor cells is their dysregulated cellular energetics with anaerobic driven glucose uptake. In patients with cancer, the prognostic value of the systemic inflammatory response has been well established, and the recent combination of PET and CT scanning combines the assessment of tumor physiologic activity with detailed anatomic localization. The aim of this study was to perform a systematic review of the assessment of the relationship between both the tumor and the host inflammatory responses using PET/CT. Methods: An extensive literature review using targeted subject headings was performed in the U.S. National Library of Medicine, the Excerpta Medica database, and the Cochrane Database of Systematic Reviews on March 31, 2018. On completion of the online search, the title and abstracts of each identified study were examined for relevance. Studies with duplicate datasets, not available in English, and that did not have full text availability were excluded. Full texts of relevant articles were obtained and were then examined to identify any further relevant articles. Results: Twelve studies containing 2,588 patients were included in the final analysis. All of the included studies used the ¹⁸F-FDG tracer in PET/CT imaging and had biochemical assessment of the systemic inflammatory response. Most studies showed a direct relationship between the tumor and bone marrow glucose uptake and host systemic inflammatory responses as measured by C-reactive protein (n = 2), albumin (n = 2), white cell count (n = 3), neutrophils (n = 2), and platelets (n = 2). Most of the studies (n = 8) also showed a direct relationship between tumor and bone marrow glucose uptake and poor outcomes. Conclusion: This review suggests a direct relationship between the tumor and bone marrow glucose uptake and host systemic inflammation. This may suggest new approaches for more optimal therapeutic targeting and monitoring strategies in patients with cancer.

Perspectives in immunotherapy: meeting report from the Immunotherapy Bridge (29-30 November, 2017, Naples, Italy)

Immunotherapy represents the third important wave in the history of the systemic treatment of cancer after chemotherapy and targeted therapy and is now established as a potent and effective treatment option across several cancer types. The clinical success of anti-cytotoxic T-lymphocyte-associated antigen (CTLA)-4, first, and anti-programmed death (PD)-1/PD-ligand (L)1 agents in melanoma and other cancers a few years later, has encouraged increasing focus on the development of other immunotherapies (e.g. monoclonal antibodies with other immune targets, adoptive cell transfer, and vaccines), with over 3000 immuno-oncology trials ongoing, involving hundreds of research institutes across the globe. The potential use of these different immunotherapeutic options in various combinations with one another and with other treatment modalities is an area of particular promise. The third Immunotherapy Bridge meeting (29-30 November, 2017, Naples, Italy) focused on recent advances in immunotherapy across various cancer types and is summarised in this report.

Toward innovative combinational immunotherapy: A systems biology perspective

The treatment of non-small-cell lung cancer (NSCLC) has advanced significantly in the last decades. Especially immune checkpoint inhibitors have shown inconceivable effect on enhancing host anti-tumor activity in NSCLC. However, the limitation of checkpoint blockade monotherapy seems unavoidable in most of the NSCLC patients and only ∼20% of them achieved response to monotherapy with immune checkpoint inhibitors. Thus combining immune checkpoint inhibitors with other agents with different action mechanisms holds a promise to revitalize NSCLC treatment, such as the combination of checkpoint inhibitors with angiogenesis inhibitors, or with chemotherapy, as well as the combination of two checkpoint inhibitors. Recently, various combinational strategies have been explored to setup promising combination regimens and to understand the action mechanisms. In this review, we summarize the suspected synergistic mechanisms of several combinational approaches by reviewing the available preclinical and clinical data. Then we discuss in light of the current knowledge of cancer biology and systems biology the important facets to be examined when setting up a framework for developing immunotherapy-based combination strategies.

Platelet Metabolism and Other Targeted Drugs; Potential Impact on Immunotherapy

The role of platelets in cancer progression has been well recognized in the field of cancer biology. Emerging studies are elaborating further the additional roles and added extent that platelets play in promoting tumorigenesis. Platelets release factors that support tumor growth and also form heterotypic aggregates with tumor cells, which can provide an immune-evasive advantage. Their most critical role may be the inhibition of immune cell function that can negatively impact the body’s ability in preventing tumor establishment and growth. This review summarizes the importance of platelets in tumor progression, therapeutic response, survival, and finally the notion of immunotherapy modulation being likely to benefit from the inclusion of platelet inhibitors.

Clinical Remission of Cutaneous Squamous Cell Carcinoma of the Auricle with Cetuximab and Nivolumab

Cutaneous squamous cell carcinomas (SCC) affecting the regions of the head and neck can be challenging to resect surgically and refractory to chemotherapy or radiation therapy. Consequently; the treatment of squamous cell carcinomas of the skin is a focus of current research. One such advancement is immunotherapy. Herein we describe clinical remission of invasive, poorly differentiated squamous cell carcinoma of the pre-auricular region with external auditory canal involvement using cetuximab, an epidermal growth factor receptor (EGFR) antibody; and nivolumab, a programmed death receptor-1 (PD-1) antibody. Such durable and comprehensive disease resolution demonstrates the therapeutic potential of cetuximab and nivolumab in surgically challenging, treatment-resistant cutaneous squamous cell carcinoma.