Protection from tumor recurrence following adoptive immunotherapy varies with host conditioning regimen despite initial regression of autochthonous murine brain tumors

Choroid plexus tumors: A spectrum from benign to malignant

Choroid plexus tumors (CPT) are believed to originate from outgrowths of the choroid plexus. Despite their broad spectrum of symptoms, invasive nature, and prognosis, most CPTs typically exhibit similar presentations due to their relationship with the cerebral ventricles, as well as the mechanical obstruction and mass effect associated with their growth. In addition, these tumors mainly affect the pediatric population, further complicating the differentiation between benign and malignant subtypes. The World Health Organization classifies CPTs into three grades, namely, grades I, II, or III, based on their mitotic activity, which determine the benign or malignant nature of the tumors. CPTs classified by the World Health Organization (WHO) include choroid plexus papillomas (CPP), atypical CPPs (aCPP), and malignant choroid plexus carcinomas (CPC). Choroid plexus adenomas represent an additional category of benign CPTs not officially classified by the WHO. Despite the variations in histology, immunohistochemistry, imaging, treatment, and prognosis, CPTs cannot be reliably distinguished based solely on clinical presentation. Therefore, in this review, we aim to provide a comprehensive overview of each tumor subtype, along with the current management approach and emerging treatments.

Behavioral Improvements following Lesion Resection for Pediatric Epilepsy: Pediatric Psychosurgery?

INTRODUCTION

Resection of brain lesions associated with refractory epilepsy to achieve seizure control is well accepted. However, concurrent behavioral effects of these lesions such as changes in mood, personality, and cognition and the effects of surgery on behavior have not been well characterized. We describe 5 such children with epileptogenic lesions and significant behavioral abnormalities which improved after surgery.

CASE DESCRIPTIONS

Five children (ages 3-14 years) with major behavioral abnormalities and lesional epilepsy were identified and treated at our center. Behavioral problems included academic impairment, impulsivity, self-injurious behavior, and decreased social interaction with diagnoses of ADHD, oppositional defiant disorder, and autism. Pre-operative neuropsychiatric testing was performed in 4/5 patients and revealed low-average cognitive and intellectual abilities for their age, attentional difficulties, and poor memory. Lesions were located in the temporal (2 gangliogliomas, 1 JPA, 1 cavernoma) and parietal (1 DNET) lobes. Gross total resection was achieved in all cases. At mean 1-year follow-up, seizure freedom (Engel 1a in 3 patients, Engel 1c in 2 patients) and significant behavioral improvements (academic performance, attention, socialization, and aggression) were achieved in all. Two patients manifested violence pre-operatively; one had extreme behavior with violence toward teachers and peers despite low seizure burden. Since surgery, his behavior has normalized.

CONCLUSION

We identified 5 patients with severe behavioral disorders in the setting of lesional epilepsy, all of whom demonstrated improvement after surgery. The degree of behavioral abnormality was disproportionate to epilepsy severity, suggesting a more complicated mechanism by which lesional epilepsy impacts behavior. We propose a novel paradigm in which lesionectomy may offer behavioral benefit even when seizures are not refractory. Thus, behavioral improvement may be an important novel goal for neurosurgical resection in children with epileptic brain lesions.

Immunotherapy for Pediatric Brain and Spine Tumors: Current State and Future Directions

BACKGROUND

Brain tumors are the most common solid tumors and the leading cause of cancer-related deaths in children. Incidence in the USA has been on the rise for the last 2 decades. While therapeutic advances in diagnosis and treatment have improved survival and quality of life in many children, prognosis remains poor and current treatments have significant long-term sequelae.

SUMMARY

There is a substantial need for the development of new therapeutic approaches, and since the introduction of immunotherapy by immune checkpoint inhibitors, there has been an exponential increase in clinical trials to adopt these and other immunotherapy approaches in children with brain tumors. In this review, we summarize the current immunotherapy landscape for various pediatric brain tumor types including choroid plexus tumors, embryonal tumors (medulloblastoma, AT/RT, PNETs), ependymoma, germ cell tumors, gliomas, glioneuronal and neuronal tumors, and mesenchymal tumors. We discuss the latest clinical trials and noteworthy preclinical studies to treat these pediatric brain tumors using checkpoint inhibitors, cellular therapies (CAR-T, NK, T cell), oncolytic virotherapy, radioimmunotherapy, tumor vaccines, immunomodulators, and other targeted therapies.

KEY MESSAGES

The current landscape for immunotherapy in pediatric brain tumors is still emerging, but results in certain tumors have been promising. In the age of targeted therapy, genetic tumor profiling, and many ongoing clinical trials, immunotherapy will likely become an increasingly effective tool in the neuro-oncologist armamentarium.

Combined sublethal irradiation and agonist anti-CD40 enhance donor T cell accumulation and control of autochthonous murine pancreatic tumors

Tumor-reactive T lymphocytes can promote the regression of established tumors. However, their efficacy is often limited by immunosuppressive mechanisms that block T cell accumulation or function. ACT provides the opportunity to ameliorate immune suppression prior to transfer of tumor-reactive T cells to improve the therapeutic benefit. We evaluated the combination of lymphodepleting whole body irradiation (WBI) and agonist anti-CD40 (αCD40) antibody on control of established autochthonous murine neuroendocrine pancreatic tumors following the transfer of naïve tumor-specific CD8 T cells. Sublethal WBI had little impact on disease outcome but did promote T cell persistence in the lymphoid organs. Host conditioning with αCD40, an approach known to enhance APC function and T cell expansion, transiently increased donor T cell accumulation in the lymphoid organs and pancreas, but failed to control tumor progression. In contrast, combined WBI and αCD40 prolonged T cell proliferation and dramatically enhanced accumulation of donor T cells in both the lymphoid organs and pancreas. This dual conditioning approach also promoted high levels of inflammation in the pancreas and tumor, induced histological regression of established tumors, and extended the lifespan of treated mice. Prolonged survival was entirely dependent upon adoptive transfer, but only partially dependent upon IFNγ production by donor T cells. Our results identify the novel combination of two clinically relevant host conditioning approaches that synergize to overcome immune suppression and drive strong tumor-specific T cell accumulation within well-established tumors.

Optimization of Peptide Vaccines to Induce Robust Antitumor CD4 T-cell Responses

Substantial evidence indicates that immunotherapy is a feasible and effective approach for the treatment of numerous types of cancer. Among various immunotherapy options, peptide vaccines to generate antitumor T cells appear as promising candidates, because of their cost effectiveness and ease of implementation. Nevertheless, most peptide vaccines are notorious for being weekly immunogenic and, thus, optimization of the vaccination strategy is essential to achieve therapeutic effectiveness. In addition, effective peptide vaccines must stimulate both CD8 cytotoxic and CD4 helper T lymphocytes. Our group has been successful in designing effective peptide vaccination strategies for inducing CD8 T-cell responses in mouse tumor models. Here, we describe a somewhat similar, but distinct, peptide vaccination strategy capable of generating vast CD4 T-cell responses by combining synthetic peptides with toll-like receptor (TLR) agonists and OX40/CD40 costimulation. This vaccination strategy was efficient in overcoming immune tolerance to a self-tumor-associated antigen and generated significant antitumor effects in a mouse model of malignant melanoma. The optimized peptide vaccine also allowed the expansion of adoptively transferred CD4 T cells without the need for lymphodepletion and IL2 administration, generating effective antimelanoma responses through the enhancement of proliferative and antiapoptotic activities of CD4 T cells. These results have practical implications in the design of more effective T-cell-based immunotherapies. Cancer Immunol Res; 5(1); 72-83. ©2016 AACR.