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Mutations that initiate acute myeloid leukemia (AML) can cause clonal expansion without transformation (clonal hematopoiesis). Cooperating mutations, usually in signaling genes, are needed to cause overt disease, but these may require a specific fitness state to be tolerated. Here, we show that nearly all AMLs arising in a mouse model expressing 2 common AML-initiating mutations (Dnmt3a\"·7· and Npm1) acquired a single copy amplification of chromosome 7 (chr7), followed by activating mutations in signaling genes. We show that overexpression of a single gene on chr7 (Cab2, which coordinates signaling pathways) was tolerated in the presence of the Npm1\" mutation, could accelerate the development of AML, and was important for the survival of fully transformed AML cells. САВ2 is likewise overexpressed in many human AMLs with mutations in NPM1 and/or signaling genes, and also in acute promyelocytic leukemia initiated by PML:RARA; the PML:RARA fusion protein may activate САВ2 by directly binding to its 5' flanking region. A similar pattern of GAB2 overexpression preceding mutations in signaling genes has been described in other human malignancies. GAB2 overexpression may represent an oncogene-driven adaptation that facilitates the action of signaling mutations, suggesting an important (and potentially targetable) missing link between the initiating and progression mutations associated with AML.

All- trans retinoic acid (ATRA) plus arsenic trioxide was found to be noninferior to ATRA plus chemotherapy, and less toxic, in the treatment of acute promyelocytic leukemia. This is an early example of a curative therapy for acute leukemia without chemotherapy. Acute promyelocytic leukemia (APL) has become a highly curable disease with contemporary treatment, which consists of all- trans retinoic acid (ATRA) and anthracycline-based chemotherapy. 1 , 2 As reported in several large multicenter trials, this combination results in overall remission rates of up to 95% and cure rates now exceeding 80%. 3 – 11 Thus, the combination of ATRA and chemotherapy is currently considered the standard of care for newly diagnosed APL. 12 Arsenic trioxide is also highly effective in the treatment of APL. Early studies conducted in China and the United States showed that this agent can induce sustained molecular remission when used as . . .

Promyelocytic leukemia nuclear bodies (PML-NBs) are PML-based nuclear structures that regulate various cellular processes. SUMOylation, the process of covalently conjugating small ubiquitin-like modifiers (SUMOs), is required for both the formation and the disruption of PML-NBs. However, detailed mechanisms of how SUMOylation regulates these processes remain unknown. Here we report that SUMO5, a novel SUMO variant, mediates the growth and disruption of PML-NBs. PolySUMO5 conjugation of PML at lysine 160 facilitates recruitment of PML-NB components, which enlarges PML-NBs. SUMO5 also increases polySUMO2/3 conjugation of PML, resulting in RNF4-mediated disruption of PML-NBs. The acute promyelocytic leukemia oncoprotein PML-RARα blocks SUMO5 conjugation of PML, causing cytoplasmic displacement of PML and disruption of PML-NBs. Our work not only identifies a new member of the SUMO family but also reveals the mechanistic basis of the PML-NB life cycle in human cells.

All-trans-retinoic acid (ATRA) is highly active in acute promyelocytic leukemia but not in other types of acute myeloid leukemia (AML). Previously, we showed that ATRA in combination with Lysine-specific demethylase 1 (LSD1) inhibition by tranylcypromine (TCP) can induce myeloid differentiation in AML blasts. This phase I/II clinical trial investigated the safety and efficacy of TCP/ATRA treatment as salvage therapy for relapsed/refractory (r/r) AML. The combination was evaluated in 18 patients, ineligible for intensive treatment. The overall response rate was 20%, including two complete remissions without hematological recovery and one partial response. We also observed myeloid differentiation upon TCP/ATRA treatment in patients who did not reach clinical remission. Median overall survival (OS) was 3.3 months, and one-year OS 22%. One patient developed an ATRA-induced differentiation syndrome. The most frequently reported adverse events were vertigo and hypotension. TCP plasma levels correlated with intracellular TCP concentration. Increased H3K4me1 and H3k4me2 levels were observed in AML blasts and white blood cells from some TCP/ATRA treated patients. Combined TCP/ATRA treatment can induce differentiation of AML blasts and lead to clinical response in heavily pretreated patients with r/r AML with acceptable toxicity. These findings emphasize the potential of LSD1 inhibition combined with ATRA for AML treatment.

Although acute promyelocytic leukemia (APL) is one of the most characterized forms of acute myeloid leukemia (AML), the molecular mechanisms involved in the development and progression of this disease are still a matter of study. APL is defined by the PML-RARA rearrangement as a consequence of the translocation t(15;17)(q24;q21). However, this abnormality alone is not able to trigger the whole leukemic phenotype and secondary cooperating events might contribute to APL pathogenesis. Additional somatic mutations are known to occur recurrently in several genes, such as FLT3, WT1, NRAS and KRAS, whereas mutations in other common AML genes are rarely detected, resulting in a different molecular profile compared to other AML subtypes. How this mutational spectrum, including point mutations in the PML-RARA fusion gene, could contribute to the 10%–15% of relapsed or resistant APL patients is still unknown. Moreover, due to the uncertain impact of additional mutations on prognosis, the identification of the APL-specific genetic lesion is still the only method recommended in the routine evaluation/screening at diagnosis and for minimal residual disease (MRD) assessment. However, the gene expression profile of genes, such as ID1, BAALC, ERG, and KMT2E, once combined with the molecular events, might improve future prognostic models, allowing us to predict clinical outcomes and to categorize APL patients in different risk subsets, as recently reported. In this review, we will focus on the molecular characterization of APL patients at diagnosis, relapse and resistance, in both children and adults. We will also describe different standardized molecular approaches to study MRD, including those recently developed. Finally, we will discuss how novel molecular findings can improve the management of this disease.

The retinoids are a group of compounds including vitamin A and its active metabolite all-trans-retinoic acid (ATRA). Retinoids regulate a variety of physiological functions in multiple organ systems, are essential for normal immune competence, and are involved in the regulation of cell growth and differentiation. Vitamin A derivatives have held promise in cancer treatment and ATRA is used in differentiation therapy of acute promyelocytic leukemia (APL). ATRA and other retinoids have also been successfully applied in a variety of dermatological conditions such as skin cancer, psoriasis, acne, and ichthyosis. Moreover, modulation of retinoic acid receptors and retinoid X (or rexinoid) receptors function may affect dermal cells. The studies using complex genetic models with various combinations of retinoic acid receptors (RARs) and retinoid X (or rexinoid) receptors (RXRs) indicate that retinoic acid and its derivatives have therapeutic potential for a variety of serious dermatological disorders including some malignant conditions. Here, we provide a synopsis of the main advances in understanding the role of ATRA and its receptors in dermatology.

Arsenicals are one of the oldest treatments for a variety of human disorders. Although infamous for its toxicity, arsenic is paradoxically a therapeutic agent that has been used since ancient times for the treatment of multiple diseases. The use of most arsenic-based drugs was abandoned with the discovery of antibiotics in the 1940s, but a few remained in use such as those for the treatment of trypanosomiasis. In the 1970s, arsenic trioxide, the active ingredient in a traditional Chinese medicine, was shown to produce dramatic remission of acute promyelocytic leukemia similar to the effect of all-trans retinoic acid. Since then, there has been a renewed interest in the clinical use of arsenicals. Here the ancient and modern medicinal uses of inorganic and organic arsenicals are reviewed. Included are antimicrobial, antiviral, antiparasitic and anticancer applications. In the face of increasing antibiotic resistance and the emergence of deadly pathogens such as the severe acute respiratory syndrome coronavirus 2, we propose revisiting arsenicals with proven efficacy to combat emerging pathogens. Current advances in science and technology can be employed to design newer arsenical drugs with high therapeutic index. These novel arsenicals can be used in combination with existing drugs or serve as valuable alternatives in the fight against cancer and emerging pathogens. The discovery of the pentavalent arsenic-containing antibiotic arsinothricin, which is effective against multidrug-resistant pathogens, illustrates the future potential of this new class of organoarsenical antibiotics.