Helping Neuro-oncologists Navigate Expanded Access

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ABSTRACT Parent grant: Genetic susceptibility plays a significant role in glioma development. An individual with two or more first- and/or second-degree affected relatives has a two-fold increased risk of the disease. We were the first to suggest mutations in POT1 (Protection of Telomeres 1) as causative in familial glioma (FG). We have now established the presence of POT1 mutations in 5 different families, providing the strongest evidence of its role in glioma. However, we do not yet have direct functional evidence that loss of POT1 is causal in glioma leaving few options for carrier surveillance or potential treatment targets. We are currently able to explain the genetic basis of glioma in up to 12% of our families, using highly stringent criteria for calling a mutation deleterious and causal. In contrast, the majority of our families remain unexplained though several candidate genes have emerged as ‘suspects of interest (SOIs)’. We propose a data-driven, knowledge-based, computational approach to guide candidate gene selection for functional characterization. In order to further our efforts to explain the genetic basis of FG we propose two specific aims to: Identify new gene candidates that may cause FG through WGS (Aim 1). We will identify SNVs, small indels, and structural variants in both coding and noncoding regions of the genome, intensively annotate those variants using more than 50 data sources, and we will rank these variants using multiple criteria based on their likelihood to cause disease. In addition to the 270 FG cases (from 203 FG families) with sequence data already available, we will also sequence an additional 100 cases (from 100 families) already collected in our Glioma International Case-Control Study with a reported family history using Gliogene criteria, and 200 newly recruited cases (from 100 families) with a strong family history of glioma to enhance our discovery, and 150 familial glioma tumor samples. The second aim is to functionally validate SOIs to include: A) POT1 mutations and B) newly discovered FG susceptibility genes (SOIs) from Aim 1 using a novel experimental mouse model of gliomagenesis. To determine the functional contributions of POT1 and novel mutations identified in our WGS studies, we will evaluate these genes in glioma mouse models using CRISPR gene editing technology. This study has the potential for future genetic testing in high-risk families, success will offer much needed insight on the underlying biology and etiology of glioma in both familial and sporadic cases. Supplement: The FDA’s expanded access program (EAP)—sometimes called “compassionate use” for individual requests—is a potential option for patients with immediate, life-threatening conditions when no comparable or satisfactory options are available to gain access to experimental medicines outside of clinical trials. Yet we know little about how oncologists and patients navigate EAP requests, their understanding of federal policy, or how they manage informed consent after a request has been approved. There is no empirically-derived ethical guidance for oncologists considering experimental drugs as treatment options for their patients. We propose to develop and offer guidance to neuro-oncologists through a stepwise approach of empirical research and normative ethics. First, we will conduct individual, in-depth interviews through family-physician dyads, and ask about their experiences in discussing options of providing an experimental drug through compassionate use or expanded access. Family cohorts will include at least two living glioma cases, and will be identified through recruitment in the Discovery, Biology and Risk of Inherited Variants in Glioma (GLIOGENE) parent grant. Then, we will combine ethical principles and paradigmatic cases from the literature with the themes and cases derived from interviews to identify salient ethical areas of concern. Once identified, we will synthesize case scenarios and questions for normative discussion with investigators on the parent grant and three practicing neuro-oncologists. This exercise will be used to generate a set of clinically-relevant recommendations and decision tools for practitioners.