x Vaccines against non-viral tumors have mainly targeted differentiation antigens, cancer testis antigens, and overexpressed antigens. However, negative selection in the thymus against these normal non-mutated antigens severely limits the ability to generate high avidity anti-cancer T-cells. Such depletion can impair their antitumor activity and limit tumor elimination. x The National Cancer Institute Surgery Branch (NCI-SB) has developed a pipeline for the identification of immunogenic T-cell epitopes derived from neoantigens. x In recent studies, we identified the neoantigens recognized by tumor-infiltrating lymphocytes (TIL) that mediated regression in patients with metast atic melanoma. Using whole exome sequencing of a resected meta static nodule followed by high throughput immunologic screening, we were able to demonstrate that tumor regressions were associated with the recognition by the administered TIL of unique somatic mutations that occurred in the cancer. x We also found that TIL from 29 of 32 patie nts with a wide variety of metastatic gastrointestinal cancers contained lymphoc ytes that recognized unique mutations presented in that patient’s cancer. x We, therefore, aim to use this pipeline to identify immunogenic neoantigens and to predict for neoantigens binding the patient human leukocyte antigen (HLA) molecules from melanoma or epithelial cancer patients and to use these epitopes for a personalized therapeutic messenger RNA (mRNA) vaccine. Objectives: x Primary objectives: o Determine the clinical response rate in patients with meta static melanoma, gastrointestinal, or genitourinary cancers who receive NCI-4650. o Determine the safety of NCI-4650 in patients with meta static melanoma, gastrointestinal, or genitourinary cancers. Eligibility: x Age  18 years DQG\HDUV x Evaluable metastatic melanoma, gastrointestin al, or genitourinary cancers refractory to standard of care treatment. x Metastatic cancer lesions suitable for surg ical resection to perform whole exome sequencing and preparation of TIL. Abbreviated Title: mRNA-Based, Cancer Vaccine Version Date: January 23, 2019 3 Design: x Patients with metasta tic cancer will undergo surgical re section of tumor followed by exome and RNA sequencing to identify expr essed mutations. This will be conducted under the NCI-SB cell harvest protocol 03- C-0277 (Cell Harvest and Preparation for Surgery Branch Adoptive Cell Therapy Protocols). x Immunogenic neoantigens will be identified from TIL by high throughput immunologic screening using long peptides and tandem minigenes covering all mutated epitopes. x Up to 15 predicted neoantigens will be selected based on exome and RNA sequencing and their binding affinity to the patient HLA molecules. x The mRNA vaccine will be manufacture d and supplied as cGMP product by ModernaTX, Inc. x The patient will be vaccinated with mRNA containing epitopes from immunogenic neoantigens, predicted neoantig ens, and mutations in tumor suppressor or driver genes. x The mRNA vaccine will be administered intramuscularly (IM) for four cycles every two weeks. A patient may receive a second course for a total of eight cycles. x Blood samples will be taken every two weeks (d uring the vaccination period) and at each follow-up visit, and patients will be monitored for the quantity and quality of circulating neoantigen-specific T-cells. Abbreviated Title: mRNA-Based, Cancer Vaccine Version Date: January 23, 2019 4TABLE OF CONTENTS PRÉCIS ........................................................................................................................ ..................