Neurofibroma, Plexiform

Background: \- Some people with cancer have solid tumors. Others have refractory leukemia. This may not go away after treatment. Researchers want to see if a drug called TURALIO(R) can shrink tumors or stop them from growing. Objectives: \- To find the highest safe dose and side effects of TURALIO(R). To see if it helps treat certain types of cancer. Eligibility: \- People ages 3-35 with a solid tumor or leukemia that has returned or not responded to cancer therapies. Design: * Individuals will be screened with: * Medical history * Physical exam * Blood and urine tests * Heart tests * Scans or other tests of the tumor * Individuals will take TURALIO(R) as a capsule once daily for a 28-day cycle. They can do this for up to 2 years. * During the study, participants will have many tests and procedures. They include repeats of the screening tests. Individuals will keep a diary of symptoms. * Individuals with solid tumors will have scans or x-rays. * Individuals with leukemia will have blood tests. They may have a bone marrow sample taken. * Some individuals may have a biopsy. * When finished taking TURALIO(R), individuals will have follow-up visits. They will repeat the screening tests and note side effects.

As part of a post-approval commitment, the Korean health authority requests a study to characterize safety and effectiveness in patients treated with Koselugo (Selumetinib), an oral selective inhibitor of MAPK kinase (MEK) 1 and 2, by physicians in routine clinical practice settings. This study is designed to assess the known safety profile or identify previously unsuspected adverse reactions and evaluate the effectiveness of Koselugo under conditions of routine daily medical practice in Korea. This study will provide information on the Korean patient population that is treated with the study drug.

The main purpose of this clinical trial is to test PAS-004 in people with at least one symptomatic plexiform neurofibroma due to Neurofibromatosis Type 1 (NF1). The main questions it aims to answer are: * How well participants are able tolerate different doses of PAS-004, and * What side effects PAS-004 might have. This study will have two parts, Part A and Part B. The main goal of Part A of this study is to learn more about how participants tolerate different doses of PAS-004, and what side effects PAS-004 might have. What we learn from Part A of the study will help decide what doses of the study drug (PAS-004) should be used in Part B of the study, and if it is safe. In Part B, two different doses from Part A will be tested. The main goal of this part of the study is to keep studying any side effects of PAS-004 at those two dose levels, and to learn more about if the doses picked for this part of the study might have an effect on plexiform neurofibromas. Participants in Part A of the study who were taking doses selected for Part B may be able to continue on to Part B and keep taking the same dose of PAS-004 for 6 more months. Study participants in both parts will have regular visits to the study doctor and be asked to have tests and exams done to check on their health and safety, including blood draws and MRIs. Everyone participating in the study will take PAS-004 by mouth once a day during the study, in 28-day cycles. Participants will be asked to keep a diary to record their daily dose of study drug. Participants will continue on daily PAS-004 for up to 6 months, or until: * They decide to withdraw from the study, or * They experience unacceptable side effects, or * Their disease progresses, or another illness interferes with taking the study drug, or * The sponsor selects a dose level to study further in the next part of the study, or * The sponsor stops the study.

Neurofibromatosis type 1 (NF1) is an autosomal dominant disease affecting chromosome 17. It is manifested by a neurogenic tumor proliferation that forms cutaneous, subcutaneous or deep neurofibromas. Neurofibromas can cause functional discomfort, neurogenic pain that is difficult to treat, and severe cosmetic disorders. Treatment is essentially surgical. It is sometimes a heavy invasive surgery with complicated postoperative follow-up and significant scarring on the aesthetic level. Currently, no systemic treatment has proven its effectiveness in this pathology. Percutaneous cryotherapy is a cold thermoablation procedure using fine 17 G needles introduced into the lesion after targeting by imaging. This technique is used in the treatment of soft tissue tumors and desmoid tumors. The treatment of neurofibromas with percutaneous cryotherapy is not well known. Encouraging results (unpublished) have been observed in patients with NF1 treated with cryotherapy at the Léon Bérard Center. The beneficial effect was observed in terms of quality of life (in particular, pain) as well as a decrease in tumor size. On the basis of this first experience, it appears important to corroborate these preliminary results by a prospective study allowing the use of this technique to treat patients with unresectable or resectable neurofibromas but with mutilating surgery in a NF1 context.