Novel TCR-like CAR-T cells targeting an HLA∗0201-restricted SSX2 epitope display strong activity against acute myeloid leukemia.

The synovial sarcoma X breakpoint 2 (SSX2) belongs to a multigene family of cancer-testis antigens and can be found overexpressed in multiple malignancies. Its restricted expression in immune-privileged normal tissues suggest that SSX2 may be a relevant target antigen for chimeric antigen receptor (CAR) therapy. We have developed a T cell receptor (TCR)-like antibody (Fab/3) that binds SSX2 peptide 41-49 (KASEKIFYV) in the context of HLA-A∗-0201. The sequence of Fab/3 was utilized to engineer a CAR with the CD3 zeta intra-cellular domain along with either a CD28 or 4-1BB costimulatory endodomain. Human T cells from HLA-A2+ donors were transduced to mediate anti-tumor activity against acute myeloid leukemia (AML) tumor cells. Upon challenge with HLA-A2+/SSX2+ AML tumor cells, CAR-expressing T cells released interferon-γ and eliminated the tumor cells in a long-term co-culture assay. Using the HLA-A2+ T2 cell line, we demonstrated a strong specificity of the single-chain variable fragment (scFv) for SSX2 p41-49 and the closely related SSX3 p41-49, with no response against the others SSX-homologous peptides or unrelated homologous peptides. Since SSX3 has not been observed in tumor cells and expression cannot be induced by pharmacological intervention, SSX241-49 represents an attractive target for CAR-based cellular therapy to treat multiple types of cancer.

Subgroup and subtype-specific outcomes in adult medulloblastoma.

Medulloblastoma, a common pediatric malignant central nervous system tumour, represent a small proportion of brain tumours in adults. Previously it has been shown that in adults, Sonic Hedgehog (SHH)-activated tumours predominate, with Wingless-type (WNT) and Group 4 being less common, but molecular risk stratification remains a challenge. We performed an integrated analysis consisting of genome-wide methylation profiling, copy number profiling, somatic nucleotide variants and correlation of clinical variables across a cohort of 191 adult medulloblastoma cases identified through the Medulloblastoma Advanced Genomics International Consortium. We identified 30 WNT, 112 SHH, 6 Group 3, and 41 Group 4 tumours. Patients with SHH tumours were significantly older at diagnosis compared to other subgroups (p < 0.0001). Five-year progression-free survival (PFS) for WNT, SHH, Group 3, and Group 4 tumours was 64.4 (48.0-86.5), 61.9% (51.6-74.2), 80.0% (95% CI 51.6-100.0), and 44.9% (95% CI 28.6-70.7), respectively (p = 0.06). None of the clinical variables (age, sex, metastatic status, extent of resection, chemotherapy, radiotherapy) were associated with subgroup-specific PFS. Survival among patients with SHH tumours was significantly worse for cases with chromosome 3p loss (HR 2.9, 95% CI 1.1-7.6; p = 0.02), chromosome 10q loss (HR 4.6, 95% CI 2.3-9.4; p < 0.0001), chromosome 17p loss (HR 2.3, 95% CI 1.1-4.8; p = 0.02), and PTCH1 mutations (HR 2.6, 95% CI 1.1-6.2; p = 0.04). The prognostic significance of 3p loss and 10q loss persisted in multivariable regression models. For Group 4 tumours, chromosome 8 loss was strongly associated with improved survival, which was validated in a non-overlapping cohort (combined cohort HR 0.2, 95% CI 0.1-0.7; p = 0.007). Unlike in pediatric medulloblastoma, whole chromosome 11 loss in Group 4 and chromosome 14q loss in SHH was not associated with improved survival, where MYCN, GLI2 and MYC amplification were rare. In sum, we report unique subgroup-specific cytogenetic features of adult medulloblastoma, which are distinct from those in younger patients, and correlate with survival disparities. Our findings suggest that clinical trials that incorporate new strategies tailored to high-risk adult medulloblastoma patients are urgently needed.

Biological Treatments of Neurofibromatosis Type 2 and Other Skull Base Disorders.

Studies of genomic alterations that occur in skull base tumors have provided information regarding biological aberrations that are necessary for the growth and maintenance of these tumors. This has led to the development and initiation of clinical trials incorporating biological treatments for many skull base tumors. The exciting developments of molecularly targeted therapy for the treatment of skull base tumors may provide noninvasive therapeutic options for patients that can be used either alone or in combination with surgery and/or radiation therapy. Future analysis and continued scientific discovery of treatments for skull base tumors can lead to improved outcomes in patients.

Considerations when treating high-grade pediatric glioma patients with immunotherapy.

INTRODUCTION: Children with high-grade gliomas (pHGGs) represent a clinical population in substantial need of new therapeutic options given the inefficacy and toxicity of current standard-of-care modalities. Although immunotherapy has emerged as a promising modality, it has yet to elicit a significant survival benefit for pHGG patients. While preclinical studies address a variety of underlying challenges, translational clinical trial design and management also need to reflect the most updated progress and lessons from the field. AREAS COVERED: The authors will focus our discussion on the design of clinical trials, the management of potential toxicities, immune monitoring, and novel biomarkers. Clinical trial design should integrate appropriate patient populations, novel, and preclinically optimized trial design, and logical treatment combinations, particularly those which synergize with standard of care modalities. However, there are caveats due to the nature of immunotherapy trials, such as patient selection bias, evidenced by the frequent exclusion of patients on high-dose corticosteroids. Robust immune-modulating effects of modern immunotherapy can have toxicities. As such, it is important to understand and manage these, especially in pHGG patients. EXPERT OPINION: Adequate integration of these considerations should allow us to effectively gain insights on biological activity, safety, and biomarkers associated with benefits for patients.

PET/CT versus bone marrow biopsy in the initial evaluation of bone marrow infiltration in various pediatric malignancies.

Accurate staging is essential in the prognosis and management of pediatric malignancies. Current protocols require screening for marrow infiltration with bone marrow biopsy (BMB) as the gold standard. Positron emission tomography-computed tomography (PET-CT) is commonly used to complete the staging process and can also be used to evaluate marrow infiltration. OBJECTIVE: To compare PET-CT and BMB in the initial evaluation of bone marrow infiltration in pediatric cancers. DESIGN/METHOD: We retrospectively reviewed new cases of EWS, rhabdomyosarcoma, neuroblastoma, and lymphoma diagnosed between January 2009 and October 2014. Each case had undergone both PET-CT and BMB within 4 weeks without treatment in the interval between screening modalities. RESULTS: We reviewed 69 cases. Bone marrow infiltration was demonstrated in 34 cases by PET-CT and in 18 cases by BMB. The sensitivity and negative predictive value of PET-CT were both 100%. Interestingly, the cases in which infiltration was not detected on BMB had an abnormal marrow signal on PET-CT focal or distant to iliac crest. CONCLUSION: PET-CT has a high sensitivity when assessing marrow infiltration in pediatric malignancies. Advances in radiologic modalities may obviate the use of invasive, painful, and costly procedures like BMB. Furthermore, biopsy results are limited by insufficient tissue or the degree of marrow infiltration (diffuse vs. focal disease). PET-CT can improve the precision of biopsy when used as a guiding tool. This study proposes the use of PET-CT as first-line screening for bone marrow infiltration to improve the accuracy of staging in new diagnoses.

Transferrin conjugated nontoxic carbon dots for doxorubicin delivery to target pediatric brain tumor cells.

Among various cancers, pediatric brain tumors represent the most common cancer type in children and the second most common cause of cancer related deaths. Anticancer drugs and therapies, such as doxorubicin (Dox), have severe side effects on patients during chemotherapy, especially for children as their bodies are still under development. These side effects are believed to be due to the lack of a delivery system with high efficacy and targeting selectivity, resulting in serious damages of normal cells. To improve the efficacy and selectivity, the transferrin (Trans) receptor mediated endocytosis can be utilized for drug delivery system design, as transferrin receptors are expressed on the blood brain barrier (BBB) and often over expressed in brain tumor cells. Carbon dots (C-Dots) have recently emerged as benign nanoparticles in biomedical applications owing to their good water solubility, tunable surface functionalities and excellent biocompatibility. The unique characteristics of C-Dots make them promising candidates for drug delivery development. In this study, carbon dots-transferrin-doxorubicin covalent conjugate (C-Dots-Trans-Dox) was synthesized, characterized by different spectroscopic techniques and investigated for the potential application as a drug delivery system for anticancer drug doxorubicin to treat pediatric brain tumors. Our in vitro results demonstrate greater uptake of the C-Dots-Trans-Dox conjugate compared to Dox alone presumably owing to the high levels of transferrin receptors on these tumor cells. Experiment showed that C-Dots-Trans-Dox at 10 nM was significantly more cytotoxic than Dox alone, reducing viability by 14-45%, across multiple pediatric brain tumor cell lines.