Identifying MAGE-A4-positive tumors for TCR T cell therapies in HLA-A∗02-eligible patients.

T cell receptor (TCR) T cell therapies target tumor antigens in a human leukocyte antigen (HLA)-restricted manner. Biomarker-defined therapies require validation of assays suitable for determination of patient eligibility. For clinical trials evaluating TCR T cell therapies targeting melanoma-associated antigen A4 (MAGE-A4), screening in studies NCT02636855 and NCT04044768 assesses patient eligibility based on: (1) high-resolution HLA typing and (2) tumor MAGE-A4 testing via an immunohistochemical assay in HLA-eligible patients. The HLA/MAGE-A4 assays validation, biomarker data, and their relationship to covariates (demographics, cancer type, histopathology, tissue location) are reported here. HLA-A∗02 eligibility was 44.8% (2,959/6,606) in patients from 43 sites across North America and Europe. While HLA-A∗02:01 was the most frequent HLA-A∗02 allele, others (A∗02:02, A∗02:03, A∗02:06) considerably increased HLA eligibility in Hispanic, Black, and Asian populations. Overall, MAGE-A4 prevalence based on clinical trial enrollment was 26% (447/1,750) across 10 solid tumor types, and was highest in synovial sarcoma (70%) and lowest in gastric cancer (9%). The covariates were generally not associated with MAGE-A4 expression, except for patient age in ovarian cancer and histology in non-small cell lung cancer. This report shows the eligibility rate from biomarker screening for TCR T cell therapies and provides epidemiological data for future clinical development of MAGE-A4-targeted therapies.

Antitumor activity without on-target off-tumor toxicity of GD2-chimeric antigen receptor T cells in patients with neuroblastoma.

The reprogramming of a patient's immune system through genetic modification of the T cell compartment with chimeric antigen receptors (CARs) has led to durable remissions in chemotherapy-refractory B cell cancers. Targeting of solid cancers by CAR-T cells is dependent on their infiltration and expansion within the tumor microenvironment, and thus far, fewer clinical responses have been reported. Here, we report a phase 1 study (NCT02761915) in which we treated 12 children with relapsed/refractory neuroblastoma with escalating doses of second-generation GD2-directed CAR-T cells and increasing intensity of preparative lymphodepletion. Overall, no patients had objective clinical response at the evaluation point +28 days after CAR-T cell infusion using standard radiological response criteria. However, of the six patients receiving ≥108/meter2 CAR-T cells after fludarabine/cyclophosphamide conditioning, two experienced grade 2 to 3 cytokine release syndrome, and three demonstrated regression of soft tissue and bone marrow disease. This clinical activity was achieved without on-target off-tumor toxicity. Targeting neuroblastoma with GD2 CAR-T cells appears to be a valid and safe strategy but requires further modification to promote CAR-T cell longevity.

Preclinical evaluation of an affinity-enhanced MAGE-A4-specific T-cell receptor for adoptive T-cell therapy.

A substantial obstacle to the success of adoptive T cell-based cancer immunotherapy is the sub-optimal affinity of T-cell receptors (TCRs) for most tumor antigens. Genetically engineered TCRs that have enhanced affinity for specific tumor peptide-MHC complexes may overcome this barrier. However, this enhancement risks increasing weak TCR cross-reactivity to other antigens expressed by normal tissues, potentially leading to clinical toxicities. To reduce the risk of such adverse clinical outcomes, we have developed an extensive preclinical testing strategy, involving potency testing using 2D and 3D human cell cultures and primary tumor material, and safety testing using human primary cell and cell-line cross-reactivity screening and molecular analysis to predict peptides recognized by the affinity-enhanced TCR. Here, we describe this strategy using a developmental T-cell therapy, ADP-A2M4, which recognizes the HLA-A2-restricted MAGE-A4 peptide GVYDGREHTV. ADP-A2M4 demonstrated potent anti-tumor activity in the absence of major off-target cross-reactivity against a range of human primary cells and cell lines. Identification and characterization of peptides recognized by the affinity-enhanced TCR also revealed no cross-reactivity. These studies demonstrated that this TCR is highly potent and without major safety concerns, and as a result, this TCR is now being investigated in two clinical trials (NCT03132922, NCT04044768).

Extraction of miRNAs from Formalin-Fixed Paraffin-Embedded (FFPE) Tissues.

miRNAs are small non-coding RNAs that regulate gene expression and are involved in numerous diseases ranging from osteoporosis, cardiovascular disease, and numerous cancer indications. Most of the clinical material that is accessible for study is archival FFPE blocks. Due to the harsh nature of fixation and embedding procedures involved in preserving clinical material, these samples are heavily fragmented and chemically cross-linked by formalin. miRNAs, due to their small size and increased stability, are easier to retrieve and study in these precious tissues. Therefore, miRNAs have become useful tools in the diagnosis, prognosis, and prediction of diseases. Due to their increased importance, isolation of miRNAs from FFPE material is extremely clinically relevant. Here, we describe the best method for miRNA extraction from FFPE tissue blocks and determine the Qiagen miRNeasy FFPE kit to be the best kit for this task.

Investigating the Experiences of Childhood Cancer Patients and Parents Participating in Optional Nontherapeutic Clinical Research Studies in the UK.

BACKGROUND: While the majority of childhood cancer clinical trials are treatment related, additional optional research investigations may be carried out that do not directly impact on treatment. It is essential that these studies are conducted ethically and that the experiences of families participating in these studies are as positive as possible. METHODS: A questionnaire study was carried out to investigate the key factors that influence why families choose to participate in optional nontherapeutic research studies, the level of understanding of the trials involved, and the experiences of participation. RESULTS: A total of 100 participants from six UK centers were studied; 77 parents, 10 patients >16 years, and 13 patients aged 8-15 years. Ninety-seven percent of parents and 90% of patients felt that information provided prior to study consent was of the right length, with 52% of parents and 65% of patients fully understanding the information provided. Seventy-four percent of parents participated in research studies in order to "do something important", while 74% of patients participated "to help medical staff". Encouragingly, <5% of participants felt that their clinical care would be negatively affected if they did not participate. Positive aspects of participation included a perception of increased attention from medical staff. Negative aspects included spending longer periods in hospital and the requirement for additional blood samples. Ninety-six percent of parents and 87% of patients would participate in future studies. CONCLUSIONS: The study provides an insight into the views of childhood cancer patients and their parents participating in nontherapeutic clinical research studies. Overwhelmingly, the findings suggest that participation is seen as a positive experience.

Pharmacokinetics of dactinomycin in a pediatric patient population: a United Kingdom Children's Cancer Study Group Study.

PURPOSE: Dactinomycin (actinomycin D) is an antitumor antibiotic used routinely to treat certain pediatric and adult cancers. Despite concerns over the incidence of toxicity, little is known about the pharmacology of dactinomycin. A study was done to investigate dactinomycin pharmacokinetics in children. EXPERIMENTAL DESIGN: Dactinomycin was administered to 31 patients by bolus i.v. infusion, at doses of 0.70 to 1.50 mg/m2. Plasma concentrations were determined by liquid chromatography-mass spectrometry up to 24 hours after drug administration and National Cancer Institute Common Toxicity Criteria was assessed. RESULTS: Pharmacokinetic data analysis suggested that a three-compartment model most accurately reflected dactinomycin pharmacokinetics. However, there was insufficient data available to fully characterize this model. A median peak plasma concentration (Cmax) of 25.1 ng/mL (range, 3.2-99.2 ng/mL) was observed at 15 minutes after administration. The median exposure (AUC0-6), determined in 16 patients with sampling to 6 hours, was 2.67 mg/L.min (range, 1.12-4.90 mg/L.min). After adjusting for body size, AUC0-6 and Cmax were positively related to dose (P = 0.03 and P = 0.04, respectively). Patients who experienced any level of Common Toxicity Criteria grade had a 1.46-fold higher AUC0-6, 95% confidence interval (1.02-2.09). AUC0-6 was higher in patients <40 kg, possibly indicating a greater toxicity risk. CONCLUSIONS: Data presented suggest that dosing of dactinomycin based on surface area is not optimal, either in younger patients in whom the risk of toxicity is greater, or in older patients where doses are capped.

Pharmacokinetically guided dosing of carboplatin in paediatric cancer patients with bilateral nephrectomy.

An approach to carboplatin dosing in children with bilateral nephrectomy using a renal function-based dosing formula with a glomerular filtration rate of zero was investigated in the current study. Carboplatin exposure was determined in a total of nine courses of chemotherapy in four patients with Wilms' tumour. Carboplatin exposures following initial dosing were less than 50% of the defined target area under the plasma concentration-time curve (AUC) in all four patients studied, with actual AUC values of between 31% and 45% of the target exposures. The use of real-time pharmacokinetic monitoring to guide dosing within a course of carboplatin treatment resulted in exposures within 15% of the target AUC in all patients. Using this information to guide dosing on additional courses of treatment in the same patient resulted in consistent exposures without the need for further monitoring or dose adjustment. These results indicate that real-time pharmacokinetic monitoring of carboplatin treatment plays a key role in ensuring that an appropriate exposure to carboplatin is achieved in children with bilateral nephrectomy. Carboplatin dosing based on patient body weight, or use of a fixed dose of carboplatin, would both be predicted to result in individual patients receiving unsatisfactory drug exposures. Further studies are warranted to further elucidate the relationship between non-renal clearance of carboplatin and patient body weight in this and other patient subpopulations where there remains concern about the optimal way to use this anticancer drug.