Acute Myeloid Leukemia (AML) is a cancer originating in the blood and bone marrow, characterized by the rapid growth of abnormal myeloid cells. These abnormal cells interfere with the production of healthy blood cells, leading to various symptoms. While initial treatments often aim to achieve remission, some patients experience a return of the leukemia. This return of the disease after a period of remission is known as relapsed AML.
Understanding Relapsed Acute Myeloid Leukemia
Relapse is confirmed through diagnostic procedures, primarily a bone marrow biopsy. During this procedure, a bone marrow sample is collected and examined to detect blast cells, which are immature leukemia cells. Relapse is diagnosed when blast cells constitute 5% or more of the bone marrow cellularity.
Advanced genetic testing also helps understand relapsed AML. Cytogenetic analysis examines chromosomes for abnormalities like translocations or deletions, providing insights into leukemia’s behavior and treatment responses. Molecular testing, such as next-generation sequencing, identifies specific gene mutations (FLT3, IDH1, IDH2, TP53) that may have contributed to relapse or guide targeted therapies. These mutations can be present at initial diagnosis or emerge during relapse, indicating clonal evolution.
Treatment Approaches for Relapsed AML
Treating relapsed AML is complex and tailored to the individual, considering the patient’s age, overall health, specific genetic mutations, and duration of initial remission. Re-induction chemotherapy is a first approach for patients fit for intensive treatment. Regimens involve combinations of drugs like high-dose cytarabine, often with an anthracycline (e.g., mitoxantrone or idarubicin) or fludarabine. The goal is to achieve a second remission, bridging to further curative options.
Targeted therapies represent an advancement, focusing on specific genetic mutations found in leukemia cells. For patients with FLT3 mutations, drugs like gilteritinib or sorafenib block the activity of the mutated FLT3 protein. Similarly, for those with IDH1 or IDH2 mutations, inhibitors such as ivosidenib and enasidenib target the abnormal IDH enzymes. These targeted agents can be administered alone or in combination with chemotherapy, depending on the patient’s profile and disease characteristics.
Allogeneic hematopoietic stem cell transplantation (HSCT) is a potentially curative treatment for eligible patients who achieve a second remission. This procedure replaces diseased bone marrow with healthy stem cells from a donor, ideally a matched sibling or unrelated donor. Donor immune cells can recognize and eliminate residual leukemia cells, a phenomenon known as the graft-versus-leukemia effect. HSCT eligibility depends on patient fitness, suitable donor availability, and achieving a second remission.
Emerging therapies are being investigated to improve outcomes for relapsed AML. Immunotherapies, such as antibody-drug conjugates like gemtuzumab ozogamicin, target specific proteins on leukemia cells and deliver a cytotoxic agent. Other novel approaches include venetoclax, a BCL-2 inhibitor, used in combination with hypomethylating agents, particularly for older or less fit patients. Clinical trials offer access to new and experimental treatments, providing additional options for patients who may not respond to standard therapies or who have specific genetic profiles.
Prognosis and Supportive Care
The prognosis for patients with relapsed AML varies significantly, influenced by several factors. These factors include the duration of the initial remission; a shorter initial remission, particularly less than six months, suggests a more aggressive disease and a higher chance of recurrence. The specific genetic profile of the relapsed leukemia, including high-risk mutations like TP53 or complex cytogenetics, impacts outcomes. The patient’s age and overall health at the time of relapse influence treatment tolerance and response.
Supportive care manages relapsed AML symptoms and treatment side effects. This includes vigilant infection prevention and treatment, as chemotherapy can weaken the immune system. Patients may require frequent blood transfusions for anemia and thrombocytopenia, common due to bone marrow suppression. Managing nausea, fatigue, and pain improves quality of life throughout treatment.
Beyond physical care, addressing the psychological and social well-being of patients and families is important. Support groups, counseling, and palliative care services provide emotional support and help navigate disease challenges. A multidisciplinary team, including oncologists, nurses, social workers, and psychologists, provides comprehensive care considering all aspects of the patient’s journey.