Robin Cornelissen

Extended Tumor Control after Dendritic Cell Vaccination with Low-Dose Cyclophosphamide as Adjuvant Treatment in Patients with Malignant Pleural Mesothelioma

RATIONALE We demonstrated previously that autologous tumor lysate-pulsed dendritic cell-based immunotherapy in patients with malignant pleural mesothelioma is feasible, well-tolerated, and capable of inducing immunologic responses against tumor cells. In our murine model, we found that reduction of regulatory T cells with metronomic cyclophosphamide increased the efficacy of immunotherapy. OBJECTIVES To assess the decrease in number of peripheral blood regulatory T cells during combination therapy of low-dose cyclophosphamide and dendritic cell immunotherapy and determine the induction of immunologic responses with this treatment in patients with mesothelioma. METHODS Ten patients with malignant pleural mesothelioma received metronomic cyclophosphamide and dendritic cell-based immunotherapy. During the treatment, peripheral blood mononuclear cells were analyzed for regulatory T cells and immunologic responses. MEASUREMENTS AND MAIN RESULTS Administration of dendritic cells pulsed with autologous tumor lysate combined with cyclophosphamide in patients with mesothelioma was safe, the only side effect being moderate fever. Dendritic cell vaccination combined with cyclophosphamide resulted in radiographic disease control in 8 of the 10 patients. Overall survival was promising, with 7 out of 10 patients having a survival of greater than or equal to 24 months and two patients still alive after 50 and 66 months. Low-dose cyclophosphamide reduced the percentage of regulatory T cells of total CD4 cells in peripheral blood from 9.43 (range, 4.34-26.10) to 4.51 (range, 0.27-10.30) after 7 days of cyclophosphamide treatment (P = 0.02). CONCLUSIONS Consolidation therapy with autologous tumor lysate-pulsed dendritic cell-based therapy and simultaneously reducing the tumor-induced immune suppression is well-tolerated and shows signs of clinical activity in patients with mesothelioma. Clinical trial registered with www.clinicaltrials.gov (NCT 01241682).

Ratio of Intratumoral Macrophage Phenotypes Is a Prognostic Factor in Epithelioid Malignant Pleural Mesothelioma

Hypothesis The tumor micro-environment and especially the different macrophage phenotypes appear to be of great influence on the behavior of multiple tumor types. M1 skewed macrophages possess anti-tumoral capacities, while the M2 polarized macrophages have pro-tumoral capacities. We analyzed if the macrophage count and the M2 to total macrophage ratio is a discriminative marker for outcome after surgery in malignant pleural mesothelioma (MPM) and studied the prognostic value of these immunological cells. Methods 8 MPM patients who received induction chemotherapy and surgical treatment were matched on age, sex, tumor histology, TNM stage and EORTC score with 8 patients who received chemotherapy only. CD8 positive T-cells and the total macrophage count, using the CD68 pan-macrophage marker, and CD163 positive M2 macrophage count were determined in tumor specimens prior to treatment. Results The number of CD68 and CD163 cells was comparable between the surgery and the non-surgery group, and was not related to overall survival (OS) in both the surgery and non-surgery group. However, the CD163/CD68 ratio did correlate with OS in both in the total patient group (Pearson r −0.72, p<0.05). No correlation between the number of CD8 cells and prognosis was found. Conclusions The total number of macrophages in tumor tissue did not correlate with OS in both groups, however, the CD163/CD68 ratio correlates with OS in the total patient group. Our data revealed that the CD163/CD68 ratio is a potential prognostic marker in epithelioid mesothelioma patients independent of treatment but cannot be used as a predictive marker for outcome after surgery.

Bronchiolitis obliterans organizing pneumonia (BOOP) after thoracic radiotherapy for breast carcinoma

Common complications of thoracic radiotherapy include esophagitis and radiation pneumonitis. However, it is important to be aware of uncommon post-radiotherapy complications such as bronchiolitis obliterans organizing pneumonia (BOOP). We report on two patients with carcinoma of the breast who developed an interstitial lung disease consistent with BOOP. BOOP responds to treatment with corticosteroids and the prognosis is generally good despite of the need for long-term administration of corticosteroids as relapses can occur during tapering of steroids. This report provides guidelines for the evaluation and treatment of patients with pulmonary infiltrates after radiotherapy.

New Roads Open Up for Implementing Immunotherapy in Mesothelioma

Treatment options for malignant mesothelioma are limited, and the results with conventional therapies have been rather disappointing to this date. Chemotherapy is the only evidence-based treatment for mesothelioma patients in good clinical condition, with an increase in median survival of only 2 months. Therefore, there is urgent need for a different approach to battle this malignancy. As chronic inflammation precedes mesothelioma, the immune system plays a key role in the initiation of this type of tumour. Also, many immunological cell types can be found within the tumour at different stages of the disease. However, mesothelioma cells can evade the surveillance capacity of the immune system. They build a protective tumour microenvironment to harness themselves against the immune systems attacks, in which they even abuse immune cells to act against the antitumour immune response. In our opinion, modulating the immune system simultaneously with the targeting of mesothelioma tumour cells might prove to be a superior treatment. However, this strategy is challenging since the tumour microenvironment possesses numerous forms of defence strategies. In this paper, we will discuss the interplay between immunological cells that can either inhibit or stimulate tumour growth and the challenges associated with immunotherapy. We will provide possible strategies and discuss opportunities to overcome these problems.

Patient-tailored modulation of the immune system may revolutionize future lung cancer treatment

Cancer research has devoted most of its energy over the past decades on unraveling the control mechanisms within tumor cells that govern its behavior. From this we know that the onset of cancer is the result of cumulative genetic mutations and epigenetic alterations in tumor cells leading to an unregulated cell cycle, unlimited replicative potential and the possibility for tissue invasion and metastasis. Until recently it was often thought that tumors are more or less undetected or tolerated by the patient’s immune system causing the neoplastic cells to divide and spread without resistance. However, it is without any doubt that the tumor environment contains a wide variety of recruited host immune cells. These tumor infiltrating immune cells influence anti-tumor responses in opposing ways and emerges as a critical regulator of tumor growth. Here we provide a summary of the relevant immunological cell types and their complex and dynamic roles within an established tumor microenvironment. For this, we focus on both the systemic compartment as well as the local presence within the tumor microenvironment of late-stage non-small cell lung cancer (NSCLC), admitting that this multifaceted cellular composition will be different from earlier stages of the disease, between NSCLC patients. Understanding the paradoxical role that the immune system plays in cancer and increasing options for their modulation may alter the odds in favor of a more effective anti-tumor immune response. We predict that the future standard of care of lung cancer will involve patient-tailor-made combination therapies that associate (traditional) chemotherapeutic drugs and biologicals with immune modulating agents and in this way complement the therapeutic armamentarium for this disease.

Checkpoint Blockade in Lung Cancer and Mesothelioma

&NA; In the last decade, immunotherapy has emerged as a new treatment modality in cancer. The most success has been achieved with the class of checkpoint inhibitors (CPIs), antibodies that unleash the antitumor immune response. After the success in melanoma, numerous clinical trials are being conducted investigating CPIs in lung cancer and mesothelioma. The programmed death protein (PD) 1‐PD ligand 1/2 pathway and cytotoxic T lymphocyte‐associated protein 4 are currently the most studied immunotherapeutic targets in these malignancies. In non‐small cell lung cancer, anti‐PD‐1 antibodies have become part of the approved treatment arsenal. In small cell lung cancer and mesothelioma, the efficacy of checkpoint inhibition has not yet been proven. In this Concise Clinical Review, an overview of the landmark clinical trials investigating checkpoint blockade in lung cancer and mesothelioma is provided. Because response rates are around 20% in the majority of clinical trials, there is much room for improvement. Predictive biomarkers are therefore essential to fully develop the potential of CPIs. To increase efficacy, multiple clinical trials investigating the combination of cytotoxic T lymphocyte‐associated protein 4 inhibitors and PD‐1/PD ligand 1 blockade in lung cancer and mesothelioma are being conducted. Given the potential benefit of immunotherapy, implementation of current and new knowledge in trial designs and interpretation of results is essential for moving forward.

Dendritic cell-based immunotherapy in mesothelioma

Mesothelioma is a rare thoracic malignancy with a dismal prognosis. Current treatment options are scarce and clinical outcomes are rather disappointing. Due to the immunogenic nature of mesothelioma, several studies have investigated immunotherapeutic strategies to improve the prognosis of patients with mesothelioma. In the last decade, progress in knowledge of the modulation of the immune system to attack the tumor has been remarkable, but the optimal strategy for immunotherapy has yet to be unraveled. Because of their potent antigen-presenting capacity, dendritic cells are acknowledged as a promising agent in immunotherapeutic approaches in a number of malignancies. This review gives an update and provides a future perspective in which immunotherapy may improve the outcome of mesothelioma therapy.

Intratumoral macrophage phenotype and CD8 + T lymphocytes as potential tools to predict local tumor outgrowth at the intervention site in malignant pleural mesothelioma

OBJECTIVES In patients with malignant pleural mesothelioma (MPM), local tumor outgrowth (LTO) after invasive procedures is a well-known complication. Currently, no biomarker is available to predict the occurrence of LTO. This study aims to investigate whether the tumor macrophage infiltration and phenotype of and/or the infiltration of CD8+ T-cells predicts LTO. MATERIALS AND METHODS Ten mesothelioma patients who developed LTO were clinically and pathologically matched with 10 non-LTO mesothelioma patients. Immunohistochemistry was performed on diagnostic biopsies to determine the total TAM (CD68), the M2 TAM (CD163) and CD8+ T-cell count (CD8). RESULTS The mean M2/total TAM ratio differed between the two groups: 0.90±0.09 in the LTO group versus 0.63±0.09 in patients without LTO (p<0.001). In addition, the mean CD8+ T-cell count was significantly different between the two groups: 30 per 0.025 cm2 (range 2-60) in the LTO group and 140 per 0.025 cm2 (range 23-314) in the patients without LTO (p<0.01). CONCLUSION This study shows that patients who develop LTO after a local intervention have a higher M2/total TAM ratio and lower CD8+ cell count at diagnosis compared to patients who did not develop this outgrowth. We propose that the M2/total TAM ratio and the CD8+ T-cell amount are potential tools to predict which MPM patients are prone to develop LTO.

Large-scale copy number analysis reveals variations in genes not previously associated with malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive tumor that is often causally associated with asbestos exposure. Comparative genomic hybridization techniques and arrays demonstrated a complex set of copy number variations (CNVs) in the MPM-genome. These techniques however have a limited resolution, throughput and flexibility compared to next-generation sequencing platforms. In this study, the presence of CNVs in the MPM-genome was investigated using an MPM-cohort (N = 85) for which genomic microarray data are available through ‘The Cancer Genome Atlas’ (TCGA). To validate these results, the genomes of MPMs and matched normal samples (N = 21) were analyzed using low-pass whole genome sequencing on an ‘Illumina HiSeq’ platform. CNVs were detected using in-house developed analysis pipelines and frequencies of copy number loss and gain were calculated. In both datasets, losses on chromosomes 1, 3, 4, 6, 9, 13 and 22 and gains on chromosomes 1, 5, 7 and 17 were found in at least 25% and 15% of MPMs, respectively. Besides the well-known MPM-associated genes, CDKN2A, NF2 and BAP1, other interesting cancer-associated genes were listed as frequently involved in a copy number loss (e.g. EP300, SETD2 and PBRM1). Moreover, four cancer-associated genes showed a high frequency of copy number gain in both datasets (i.e. TERT, FCGR2B, CD79B and PRKAR1A). A statistically significant association between overall survival and the presence of copy number loss in the CDKN2A-containing region was observed in the TCGA-set. In conclusion, recurrent CNVs were detected in both datasets, occurring in regions harboring known MPM-associated genes and genes not previously linked to MPM.

Precision immunotherapy; dynamics in the cellular profile of pleural effusions in malignant mesothelioma patients

OBJECTIVES Clinical studies have proven the potential of immunotherapy in malignancies. To increase efficacy, a prerequisite is that treatment is tailored, so precision immune-oncology is the logical next step. In order to tailor treatment, characterization of the patients tumor environment is key. Pleural effusion (PE) often accompanies malignant pleural mesothelioma (MPM) and is an important part of the MPM environment. Furthermore, the composition of PE is used as surrogate for the tumor. In this study, we provide an insight in the dynamics of the MPM environment through characterization of PE composition over time and show that the immunological characteristics of PE do not necessarily mirror those of the tumor. MATERIALS AND METHODS From 5 MPM patients, PE and tumor biopsies were acquired at the same time point. From one of these patients multiple PEs were obtained. PEs were acquired performing thoracocenteses and total cell amounts were determined. Immunohistochemistry was performed to quantify immune cell composition (T cells, macrophages) and tumor cells in PE derived cytospins and tumor biopsies. RESULTS The PE amount and (immune) cellular composition varied considerably over time between multiple (n=10) thoracocenteses. These dynamics could in part be attributed to the treatment regimen consisting of standard chemotherapy and dendritic cell (DC)-based immunotherapy. In addition, the presence of T cells and macrophages in PE did not necessarily mirror the infiltration of these immune cells within tumor biopsies in 4 out of 5 patients. CONCLUSIONS In this proof-of-concept study with limited sample size, we demonstrate that the composition of PE is dynamic and influenced by treatment. Furthermore, the immune cell composition of PE does not automatically reflect the properties of tumor tissue. This has major consequences when applying precision immunotherapy based on PE findings in patients. Furthermore, it implies a regulated trafficking of immune regulating cells within the tumor environment.