A Phase 1/2, Multicenter, Open-Label, Randomized Dose Ranging and Expansion Study of the Combination of Gilteritinib, Venetoclax and Azacitidine in Patients With Newly Diagnosed FLT3 Mutated Acute Myeloid Leukemia (AML) Not Eligible for Intensive Induction Chemotherapy

People with acute myeloid leukemia (AML) are usually treated with chemotherapy. Some people with AML have a changed FLT3 gene which causes leukemia cells to grow faster. Therefore, chemotherapy is less suitable to treat AML in people with the changed FLT3 gene. Gilteritinib, given with venetoclax and azacitidine, is a potential new treatment for people with AML with the changed FLT3 gene. They cannot have chemotherapy due to old age or other conditions. Before these combined 3 medicines are available as a treatment, the researchers need to understand how they are processed by and act upon the body when given together. In this study, they do this to find a suitable dose for venetoclax and to check for potential medical problems from the treatment. In this study, people newly diagnosed with AML who have the changed FLT3 gene and cannot have chemotherapy can take part. The main aims of this study are: to find suitable doses of gilteritinib, venetoclax and azacitidine as a combined treatment; to learn how they are processed by and act upon the body; to learn the remission rate; to check for medical problems during this treatment. In the study, people will visit the study clinic many times. The first visit is to check if they can take part. People will be asked about their medical history, have a medical examination, and have their vital signs checked. Also, they will have an ECG to check their heart rhythm and have some blood and urine samples taken for laboratory tests. They will have a chest X-ray and a bone marrow sample will be taken. The changed FLT3 gene will be confirmed, either by the bone marrow or a blood sample. This study will be in 2 phases. In Phase 1, different small groups of people will take venetoclax tablets containing lower to higher doses in the combined treatment. The doses of gilteritinib and azacytidine will be unchanged. This is done to find a suitable dose of venetoclax to use in phase 2 of the study. People will take tablets of gilteritinib and venetoclax once a day on a 28-day cycle. They will be given azacytidine as an infusion or an injection just under the skin. This will be for 7 days at the beginning of each 28-day cycle. They will continue cycles of treatment throughout this phase of the study. In Phase 2, more people newly diagnosed with AML with the changed FLT3 gene will take part. They will be treated with the suitable doses of the combined treatment worked out from Phase 1. Treatment will be on a 28-day cycle. People will continue on cycles of treatment throughout this phase of the study. Researchers will work out the remission rate from this phase of the study. In each phase of the study, people can continue with up to 12 cycles of treatment if they can manage any medical problems. People will visit the study clinic many times during their first treatment cycle, and less often during the next cycles. During these visits, medical problems will be recorded and some blood samples will be taken for laboratory tests. On some visits, people will also have their vital signs checked. Bone marrow samples will be taken during cycle 1, and at the beginning of cycle 3. More samples will be taken during the study from people who are not in remission. When people have finished treatment, those who have responded well to treatment and are in remission will be invited to continue with up to 24 more cycles of gilteritinib plus azacitidine. All people taking part in the study will visit the study clinic for an end-of-treatment visit. During this visit, medical problems will be recorded and some blood samples will be taken for laboratory tests. People will have a medical examination, an ECG, and will have their vital signs checked. Also, a bone marrow sample will be taken. There will be a follow-up visit 30 days later to check for medical problems. Then people will visit the clinic or get a phone call every 3 months for up to 3 years. This is to give an update on their current treatment for AML. Some people can have a stem cell transplant during the study if they meet certain study rules. They will pause their study treatment during the stem cell transplant process and continue study treatment afterwards.