This is associated with the development of dyspnea, fever, weight gain, peripheral edema and is treated with dexamethasone. The etiology of retinoic acid syndrome has been attributed to capillary leak syndrome from cytokine release from the differentiating promyelocytes.The monoclonal antibody, gemtuzumab ozogamicin, has been used successfully as a treatment for APL, although it has been withdrawn from the US market due to concerns regarding potential toxicity of the drug and it is not currently marketed in Australia, Canada or the UK. Given in conjunction with ATRA, it produces a response in around 84% of patients with APL, which is comparable to the rate seen in patients treated with ATRA and anthracycline-based therapy. It produces less cardiotoxicity than anthracycline-based treatments and hence may be preferable in these patients. Maintenance therapy
After stable remission was induced, the standard of care previously was to undergo 2 years of maintenance chemotherapy with methotrexate, mercaptopurine and ATRA. A significant portion of patients relapsed without consolidation therapy. In the 2000 European APL study, the 2-year relapse rate for those that did not receive consolidation chemotherapy (ATRA not included) therapy was 27% compared to 11% in those that did receive consolidation therapy (p<0.01). Likewise in the 2000 US APL study, the survival rates in those receiving ATRA maintenance was 61% compared to just 36% without ATRA maintenance.However, recent research on consolidation therapy following ATRA-ATO, which became the standard treatment in 2013, has found that maintenance therapy in low-risk patients following this therapy may be unnecessary, although this is controversial.
Most deaths following remission are from other causes, such as second malignancies, which in one study occurred in 8% of patients. In this study, second malignancies accounted for 41% of deaths, and heart disease, 29%. Survival rates were 88% at 6.3 years and 82% at 7.9 years.In another study, 10-year survival rate was estimated to be approximately 77%. Epidemiology
Acute promyelocytic leukemia represents 10–12% of AML cases. The median age is approximately 30–40 years, which is considerably younger than the other subtypes of AML (70 years), however in elderly population APL has peculiar characteristics. Incidence is higher among individuals of Latin American or South European origin. It can also occur as a secondary malignancy in those that receive treatment with topoisomerase II inhibitors (such as the anthracyclines and etoposide) due to the carcinogenic effects of these agents, with patients with breast cancer representing the majority of such patients. Around 40% of patients with APL also have a chromosomal abnormality such as trisomy 8 or isochromosome 17 which do not appear to impact on long-term outcomes. References
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Sanz, Miguel A.; Grimwade, David; Tallman, Martin S.; Lowenberg, Bob; Fenaux, Pierre; Estey, Elihu H.; Naoe, Tomoki; Lengfelder, Eva; Büchner, Thomas; Döhner, Hartmut; Burnett, Alan K.; Lo-Coco, Francesco (2009). "Management of acute promyelocytic leukemia: Recommendations from an expert panel on behalf of the European Leukemia Net". Blood. 113 (9): 1875–1891. doi:10.1182/blood-2008-04-150250. hdl:1765/18239. PMID 18812465. PDQ Adult Treatment Editorial Board (2002–2020). "Adult Acute Myeloid Leukemia Treatment (PDQ®): Patient Version". Adult Acute Myeloid Leukemia Treatment (PDQ®). National Cancer Institute (US). PMID 26389377.