Identifying STRN3-RARA as a new fusion gene for acute promyelocytic leukemia.

Here we report a new fusion gene, STRN3-RARA, in acute promyelocytic leukemia (APL). It cooperates with UTX deficiency to drive full-blown APL in mice. Although STRN3-RARA leukemia quickly relapses after all-trans retinoic acid treatment, it can be restrained by cepharanthine.

Identification of novel immune-related signatures for keloid diagnosis and treatment: insights from integrated bulk RNA-seq and scRNA-seq analysis.

BACKGROUND: Keloid is a disease characterized by proliferation of fibrous tissue after the healing of skin tissue, which seriously affects the daily life of patients. However, the clinical treatment of keloids still has limitations, that is, it is not effective in controlling keloids, resulting in a high recurrence rate. Thus, it is urgent to identify new signatures to improve the diagnosis and treatment of keloids. METHOD: Bulk RNA seq and scRNA seq data were downloaded from the GEO database. First, we used WGCNA and MEGENA to co-identify keloid/immune-related DEGs. Subsequently, we used three machine learning algorithms (Randomforest, SVM-RFE, and LASSO) to identify hub immune-related genes of keloid (KHIGs) and investigated the heterogeneous expression of KHIGs during fibroblast subpopulation differentiation using scRNA-seq. Finally, we used HE and Masson staining, quantitative reverse transcription-PCR, western blotting, immunohistochemical, and Immunofluorescent assay to investigate the dysregulated expression and the mechanism of retinoic acid in keloids. RESULTS: In the present study, we identified PTGFR, RBP5, and LIF as KHIGs and validated their diagnostic performance. Subsequently, we constructed a novel artificial neural network molecular diagnostic model based on the transcriptome pattern of KHIGs, which is expected to break through the current dilemma faced by molecular diagnosis of keloids in the clinic. Meanwhile, the constructed IG score can also effectively predict keloid risk, which provides a new strategy for keloid prevention. Additionally, we observed that KHIGs were also heterogeneously expressed in the constructed differentiation trajectories of fibroblast subtypes, which may affect the differentiation of fibroblast subtypes and thus lead to dysregulation of the immune microenvironment in keloids. Finally, we found that retinoic acid may treat or alleviate keloids by inhibiting RBP5 to differentiate pro-inflammatory fibroblasts (PIF) to mesenchymal fibroblasts (MF), which further reduces collagen secretion. CONCLUSION: In summary, the present study provides novel immune signatures (PTGFR, RBP5, and LIF) for keloid diagnosis and treatment, and identifies retinoic acid as potential anti-keloid drugs. More importantly, we provide a new perspective for understanding the interactions between different fibroblast subtypes in keloids and the remodeling of their immune microenvironment.

Fast proliferating and slowly migrating non-small cell lung cancer cells are vulnerable to decitabine and retinoic acid combinatorial treatment.

Non-small cell lung cancer (NSCLC) patients are often elderly or unfit and thus cannot tolerate standard aggressive therapy regimes. In our study, we test the efficacy of the DNA-hypomethylating agent decitabine (DAC) in combination with all-trans retinoic acid (ATRA), which has been shown to possess little systemic adverse effects. Screening a broad panel of 56 NSCLC cell lines uncovered a decrease in cell viability after the combination treatment in 77% of the cell lines. Transcriptomics, proteomics, proliferation and migration profiling revealed that fast proliferating and slowly migrating cell lines were more sensitive to the drug combination. The comparison of mutational profiles found oncogenic KRAS mutations only in sensitive cells. Additionally, different cell lines showed a heterogeneous gene expression response to the treatment pointing to diverse mechanisms of action. Silencing KRAS, RIG-I or RARB partially reversed the sensitivity of KRAS-mutant NCI-H460 cells. To study resistance, we generated two NCI-H460 cell populations resistant to ATRA and DAC, which migrated faster and proliferated slower than the parental sensitive cells and showed signs of senescence. In summary, this comprehensive dataset uncovers a broad sensitivity of NSCLC cells to the combinatorial treatment with DAC and ATRA and indicates that migration and proliferation capacities correlate with and could thus serve as determinants for drug sensitivity in NSCLC.

Venetoclax overcomes resistance to all-trans retinoic acid in a variant acute promyelocytic leukemia with TNRC18::RARA fusion.

Acute promyelocytic leukemia (APL) is generally driven by PML::RARA, but approximately 2% of variant APL patients do not contain this fusion gene and pose challenges in diagnosis and treatment. Here, we reported an aggressive APL patient with variant TNRC18::RARA fusion gene, who was resistant to standard differentiation induction therapy consisting of all-trans retinoic acid (ATRA) and arsenic trioxide but achieved complete remission with venetoclax plus ATRA. Mechanistically, venetoclax possesses synergistic effects in ATRA-induced TNRC18::RARA-positive cell differentiation.

All-trans retinoic acid plus low-dose rituximab vs low-dose rituximab in corticosteroid-resistant or relapsed ITP.

The study aimed to compare the efficacy and safety of all-trans retinoic acid (ATRA) plus low-dose rituximab (LD-RTX) with LD-RTX monotherapy in corticosteroid-resistant or relapsed immune thrombocytopenia (ITP) patients. Recruited patients were randomized at a ratio of 2:1 into 2 groups: 112 patients received LD-RTX plus ATRA, and 56 patients received LD-RTX monotherapy. Overall response (OR), defined as achieving a platelet count of ≥30 × 109/L confirmed on ≥2 separate occasions (≥7 days apart), at least a doubling of the baseline platelet count without any other ITP-specific treatment, and the absence of bleeding within 1 year after enrollment, was observed in more patients in the LD-RTX plus ATRA group (80%) than in the LD-RTX monotherapy group (59%) (between-group difference, 0.22; 95% CI, 0.07-0.36). Sustained response (SR), defined as maintenance of a platelet count >30 × 109/L, an absence of bleeding, and no requirement for any other ITP-specific treatment for 6 consecutive months after achievement of OR during 1 year following enrollment, was achieved by 68 (61%) patients in the combination group and 23 (41%) patients in the monotherapy group (between-group difference, 0.20; 95% CI, 0.04-0.35). The 2 most common adverse events (AEs) for the combination group were dry skin and headache or dizziness. Our findings demonstrated that ATRA plus LD-RTX significantly increased the overall and sustained response, indicating a promising treatment option for corticosteroid-resistant or relapsed adult ITP. This study is registered at www.clinicaltrials.gov as #NCT03304288.

Tretinoin improves the anti-cancer response to cyclophosphamide, in a model-selective manner.

BACKGROUND: Chemotherapy is included in treatment regimens for many solid cancers, but when administered as a single agent it is rarely curative. The addition of immune checkpoint therapy to standard chemotherapy regimens has improved response rates and increased survival in some cancers. However, most patients do not respond to treatment and immune checkpoint therapy can cause severe side effects. Therefore, there is a need for alternative immunomodulatory drugs that enhance chemotherapy. METHODS: We used gene expression data from cyclophosphamide (CY) responders and non-responders to identify existing clinically approved drugs that could phenocopy a chemosensitive tumor microenvironment (TME), and tested combination treatments in multiple murine cancer models. RESULTS: The vitamin A derivative tretinoin was the top predicted upstream regulator of response to CY. Tretinoin pre-treatment induced an inflammatory, interferon-associated TME, with increased infiltration of CD8 + T cells, sensitizing the tumor to subsequent chemotherapy. However, while combination treatment significantly improved survival and cure rate in a CD4+ and CD8+ T cell dependent manner in AB1-HA murine mesothelioma, this effect was model-selective, and could not be replicated using other cell lines. CONCLUSIONS: Despite the promising data in one model, the inability to validate the efficacy of combination treatment in multiple cancer models deprioritizes tretinoin/cyclophosphamide combination therapy for clinical translation.

The influence of hospital volume and physician volume on early mortality in acute promyelocytic leukemia patients.

Acute promyelocytic leukemia (APL) is a highly curable hematologic malignancy in the era of all-trans retinoic acid (ATRA) combination treatment. However, only a modest change in early mortality rate has been observed despite the wide availability of ATRA. In addition to the clinical characteristics of APL patients, studies on the hospital volume-outcome relationship and the physician volume-outcome relationship remained limited. We aim to evaluate the association between hospital and physician volume and the early mortality rate among APL patients. The patients were collected from Taiwan's National Health Insurance Research Database (NHIRD). Early mortality is defined as death within 30 days of diagnosis. Patients were categorized into four groups according to individual cumulative hospital and physician volume. The risk of all-cause mortality in APL patients with different cumulative volume groups was compared using a Cox proportional hazard model. The probability of overall survival was estimated using the Kaplan-Meier method. All 741 patients were divided into four quartile volume groups. In the multivariate analysis, only physician volume was significantly associated with early mortality rate. The physician volume of the highest quartile was a protective factor for early mortality compared with the physician volume of the lowest quartile (HR 0.10, 95% CI 0.02-0.65). Hospital characteristics were not associated with early mortality. In the sensitivity analyses, the results remained consistent using two other different definitions of early mortality. Higher physician volume was independently associated with lower early mortality, while hospital volume was not. Enhancing the clinical expertise of low-volume physicians may ensure better outcomes.

Identification of a novel fusion gene, RARA::ANKRD34C, in acute promyelocytic leukemia.

Acute promyelocytic leukemia (APL) is a specific subtype of acute myeloid leukemia that is distinguished by the chromosomal translocation t(15;17)(q24;q21), which leads to the fusion of the promyelocytic leukemia (PML) gene with the retinoic acid receptor alpha (RARA). Recently, we identified a novel fusion gene in APL, RARA::ankyrin repeat domain 34C (ANKRD34C), identified its functions by morphological, cytogenetic, molecular biological and multiplex fluorescence in situ hybridization analyses, and demonstrated the potential therapeutic effect clinically and experimentally of all-trans retinoic acid (ATRA); the findings have important implications for the diagnosis and treatment of atypical APL.

All-trans retinoic acid pretreatment of mesenchymal stem cells enhances the therapeutic effect on acute kidney injury.

A promising new therapy option for acute kidney injury (AKI) is mesenchymal stem cells (MSCs). However, there are several limitations to the use of MSCs, such as low rates of survival, limited homing capacity, and unclear differentiation. In search of better therapeutic strategies, we explored all-trans retinoic acid (ATRA) pretreatment of MSCs to observe whether it could improve the therapeutic efficacy of AKI. We established a renal ischemia/reperfusion injury model and treated mice with ATRA-pretreated MSCs via tail vein injection. We found that AKI mice treated with ATRA-MSCs significantly improved renal function compared with DMSO-MSCs treatment. RNA sequencing screened that hyaluronic acid (HA) production from MSCs promoted by ATRA. Further validation by chromatin immunoprecipitation experiments verified that retinoic acid receptor RARα/RXRγ was a potential transcription factor for hyaluronic acid synthase 2. Additionally, an in vitro hypoxia/reoxygenation model was established using human proximal tubular epithelial cells (HK-2). After co-culturing HK-2 cells with ATRA-pretreated MSCs, we observed that HA binds to cluster determinant 44 (CD44) and activates the PI3K/AKT pathway, which enhances the anti-inflammatory, anti-apoptotic, and proliferative repair effects of MSCs in AKI. Inhibition of the HA/CD44 axis effectively reverses the renal repair effect of ATRA-pretreated MSCs. Taken together, our study suggests that ATRA pretreatment promotes HA production by MSCs and activates the PI3K/AKT pathway in renal tubular epithelial cells, thereby enhancing the efficacy of MSCs against AKI.

Disseminated intravascular coagulation score evolution in 48 h predicts early death in acute promyelocytic leukemia patients.

INTRODUCTION: Early death (ED) is the unsolved issue of acute promyelocytic leukemia (APL). The disseminated intravascular coagulation (DIC) score has been proposed as a marker of bleeding and death in APL; whether its temporal evolution predicts outcomes in APL is unknown. We evaluated whether an increasing score 48 h after diagnosis associates with ED. METHODS: Retrospective, single-center study, including patients with newly diagnosed APL between 2000 and 2023, treated with all-transretinoic acid (ATRA) plus anthracycline or arsenic trioxide (ATO). "DIC score worsening" was defined as ≥1 point increase in the score after 48 h, and ED as death within 30 days of diagnosis. RESULTS: Eighty-six patients were included, with median age of 46 years (17-82). ED patients (26.7%) more frequently had age >60 years and worsening DIC score after 48 h. These were also the only predictors of ED identified in both univariate and multivariate (OR 4.18, p = .011; OR 7.8, p = .005, respectively) logistic regression analysis. CONCLUSION: This is the first study on DIC score evolution in APL-a worsening DIC score 48 h after diagnosis is a strong independent predictive factor of ED. We propose a reduction of the DIC score from diagnosis as a new treatment goal in APL care.

Comparison of the clinical efficacy of topical tretinoin 0.05% cream and tacrolimus 0.1% ointment plus iontophoresis in the management of palmoplantar psoriasis.

BACKGROUND: Palmoplantar psoriasis (PPP) is a localized variant of psoriasis that may be resistant to topical therapy, owing to the poor penetrability of topical agents at this anatomical site. Modalities that enhance localized cutaneous delivery of drugs could help to solve this problem. Iontophoresis is one such procedure that augments transdermal drug delivery, thus enabling better and expeditious therapeutic outcomes. OBJECTIVE: To compare the therapeutic efficacy and safety of iontophoresis with tretinoin 0.05% cream and tacrolimus 0.1% ointment in treating patients with PPP. METHODS: Sixty patients with PPP (28 males and 32 females, age range 8-76 years) were enrolled and randomly assigned to one of two groups comprising 30 patients each. One group (12 males and 18 females) received iontophoresis with tretinoin 0.05% cream; the other (16 males and 14 females) received iontophoresis treatment with tacrolimus 0.1% ointment. Both groups received treatment weekly from baseline until 4 weeks and then fortnightly at weeks 6 and 8. Clinical images were taken at each visit and improvement of psoriasis was evaluated using the erythema, scaling, induration and fissuring (ESIF) score. The percentage reduction in ESIF score was also assessed on completion of treatment and the grade of improvement noted for each patient. RESULTS: Twenty-seven patients in the iontophoresis with tretinoin 0.05% cream group and 29 in the iontophoresis treatment with tacrolimus 0.1% ointment group completed the study. The mean (SD) ESIF score in the former decreased significantly from 8.7 (2) at baseline to 3.2 (1.7) at the study endpoint (P < 0.001). Similarly, in the latter group, there was a substantial reduction in mean (SD) ESIF score from 8.2 (1.9) at baseline to 3.3 (1.1) at the study end (P < 0.001). No significant adverse effects were encountered in either treatment arm. CONCLUSIONS: Iontophoresis using tretinoin and tacrolimus was found to be effective and safe for the treatment of PPP. Although iontophoresis with tretinoin showed slightly better results than with tacrolimus, these were not statistically significant.

Application of cantharidin, retinoic acid cream and salicylic acidy in multiple palmoplantar warts.

OBJECTIVE: Multiple palmoplantar warts, caused by human papillomavirus (HPV) infection, were investigated for clinical efficacy using cantharidin, retinoic acid cream, and salicylic acid cream. METHODS: A total of 110 patients with multiple palmoplantar warts were enrolled. The experimental group (54 cases) received a 1:1:1 combination (CRS) of 0.25% cantharidin, 0.1% retinoic acid cream, and 5% salicylic acid, applied with pressurized encapsulation for 8 h every night, three times per week. The control group (56 cases) underwent conventional liquid nitrogen freezing. Monthly follow-ups assessed cure rate, effective rate, dermatological life quality index (DLQI), visual analog scale (VAS), and cost, with evaluations conducted after 3 months. RESULTS: The treatment group exhibited a cure rate of 85.19% and a total effective rate of 96.30%, surpassing the control group with rates of 39.29% and 51.79%, respectively (p < 0.05). The treatment group's DLQI score (1.84 ± 1.06) was significantly lower than the control group's score (6.04 ± 1.78) (p = 0.0005). Additionally, the treatment group's VAS score (1.84 ± 1.06) was notably lower than the control group's score (8.56 ± 1.07) (p < 0.0001). The treatment group's total cost (43.20 ± 2.85) was markedly lower than the control group's cost (206.38 ± 90.81), with a statistically significant difference (p < 0.0001). CONCLUSION: The combination of cantharidin, retinoic acid cream, and salicylic acid with local encapsulation is a safe, effective, economical, and convenient treatment method for multiple palmoplantar warts, exhibiting few side effects and showing promise.

All-trans retinoic acid exhibits anti-proliferative and differentiating activity in Merkel cell carcinoma cells via retinoid pathway modulation.

BACKGROUND: The limited therapies available for treating Merkel cell carcinoma (MCC), a highly aggressive skin neoplasm, still pose clinical challenges, and novel treatments are required. Targeting retinoid signalling with retinoids, such as all-trans retinoic acid (ATRA), is a promising and clinically useful antitumor approach. ATRA drives tumour cell differentiation by modulating retinoid signalling, leading to anti-proliferative and pro-apoptotic effects. Although retinoid signalling is dysregulated in MCC, ATRA activity in this tumour is unknown. This study aimed to evaluate the impact of ATRA on the pathological phenotype of MCC cells. METHODS: The effect of ATRA was tested in various Merkel cell polyomavirus-positive and polyomavirus-negative MCC cell lines in terms of cell proliferation, viability, migration and clonogenic abilities. In addition, cell cycle, apoptosis/cell death and the retinoid gene signature were evaluated upon ATRA treatments. RESULTS: ATRA efficiently impaired MCC cell proliferation and viability in MCC cells. A strong effect in reducing cell migration and clonogenicity was determined in ATRA-treated cells. Moreover, ATRA resulted as strongly effective in arresting cell cycle and inducing apoptosis/cell death in all tested MCC cells. Enrichment analyses indicated that ATRA was effective in modulating the retinoid gene signature in MCC cells to promote cell differentiation pathways, which led to anti-proliferative and pro-apoptotic/cell death effects. CONCLUSIONS: These results underline the potential of retinoid-based therapy for MCC management and might open the way to novel experimental approaches with other retinoids and/or combinatorial treatments.

Benefit of Topical Combination Therapy for Acne: Analyzing Effect Size Using Number Needed to Treat.

BACKGROUND: Topical acne trials often are confounded by high vehicle response rates and differing outcome measures, making it difficult to compare treatments. Number needed to treat (NNT) can be a simple, clinically meaningful way to indirectly compare treatment options without head-to-head data. NNT is the number of patients who need to be treated with an intervention to observe one additional patient successfully achieving a desired outcome versus vehicle/placebo. While treatment attributes such as adverse events may not be captured, lower NNT is a good indicator of a more effective treatment. METHODS: Following a search of combination topical treatments for acne vulgaris, all treatments that reported pivotal trial efficacy data consistent with the 2018 FDA definition of success were included in NNT analyses.  Results: Of 13 treatments, 7 reported 12-week treatment success rates in 11 phase 3 trials, with similar baseline demographics/disease severity. Treatment success ranged from 26.8% with tretinoin 0.1%/benzoyl peroxide (BPO) 3% cream to 50% with triple-combination clindamycin phosphate 1.2%/adapalene 0.15%/BPO 3.1% gel. NNTs for the triple-combination gel were 4 and 5 (from 2 pivotal trials). Adapalene 0.3%/BPO 2.5% gel had an NNT of 5. Tretinoin/BPO had the largest range between trials, with NNTs of 4 and 9. The other 4 treatments had NNTs ranging from 6 to 8. CONCLUSION: A comparison of combination topical acne treatment trial data, using the same treatment outcome and similar patient populations, resulted in triple-combination clindamycin phosphate/adapalene/BPO gel and adapalene/BPO gel having the most favorable NNTs.J Drugs Dermatol. 2024;23(2):42-49.  doi:10.36849/JDD.7927.

Function of PML-RARA in Acute Promyelocytic Leukemia.

The transformation of acute promyelocytic leukemia (APL) from the most fatal to the most curable subtype of acute myeloid leukemia (AML), with long-term survival exceeding 90%, has represented one of the most exciting successes in hematology and in oncology. APL is a paradigm for oncoprotein-targeted cure.APL is caused by a 15/17 chromosomal translocation which generates the PML-RARA fusion protein and can be cured by the chemotherapy-free approach based on the combination of two therapies targeting PML-RARA: retinoic acid (RA) and arsenic. PML-RARA is the key driver of APL and acts by deregulating transcriptional control, particularly RAR targets involved in self-renewal or myeloid differentiation, also disrupting PML nuclear bodies. PML-RARA mainly acts as a modulator of the expression of specific target genes: genes whose regulatory elements recruit PML-RARA are not uniformly repressed but also may be upregulated or remain unchanged. RA and arsenic trioxide directly target PML-RARA-mediated transcriptional deregulation and protein stability, removing the differentiation block at promyelocytic stage and inducing clinical remission of APL patients.

Tretinoin (2,4-difluoro-phenyl) triazole activates proapoptotic protein expression and targets NRP2 protein to inhibit esophageal carcinoma cell growth.

The present study investigated the effect of tretinoin (2,4-difluoro-phenyl) triazole (TDFPT) on the growth and proliferation of Kyse-270 and EC9706 esophageal carcinoma cells and explored the underlying mechanism. The results demonstrated that TDFPT treatment of Kyse-270 and EC9706 cells led to a dose-dependent reduction in cell proliferation. Colony formation was significantly (p < .05) reduced in Kyse-270 and EC9706 cells on treatment with various concentrations of TDFPT. In TDFPT-treated Kyse-270 and EC9706 cells, the expression of Bcl-2 protein showed a remarkable decrease, whereas the level of Bax protein was found to be higher compared with the control cells. Cell invasion showed a prominent decrease in Kyse-270 and EC9706 cells on treatment with TDFPT. Treatment with TDFPT led to a prominent suppression in the expression of MMP-9 and NRP2 in Kyse-270 and EC9706 cells. In silico studies using the AutoDock Vina and discovery studio software revealed that various confirmations of TDFPT bind to NRP2 protein with the affinity ranging from -8.6 to -6.1 kcal/mol. It was found that the TDFPT interacts with NRP2 protein by binding to alanine (ALA A:295), proline (PRO A:306), glutamine (GLN A:307), and isoleucine (ILE A:293) amino acid residues. In summary, TDFPT exposure suppresses esophageal carcinoma cell proliferation, inhibits colony formation ability, and activates apoptotic pathway. Thus, TDFPT acts as an effective antiproliferative agent for esophageal carcinoma cells and needs to be investigated further as chemotherapeutic molecule.

Protective effect of tretinoin on cervical cancer growth and proliferation through downregulation of pFAK2 expression.

BACKGROUND: Cervical cancer, a life-threatening disease, is the seventh most commonly detected cancer among women throughout the world. The present study investigated the effect of tretinoin on cervical cancer growth and metastasis in vitro and in vivo in the mice model. MATERIALS AND METHODS: Cell Counting Kit-8, clonogenic survival, and transwell chamber assays were used for determination cells proliferation, colony formation, and invasiveness. Western blotting assay was used for assessment of protein expression whereas AutoDock Vina and Discovery studio software for in silico studies. RESULTS: Tretinoin treatment significantly (p < .05) reduced the proliferation of HT-3 and Caski cells in concentration-based manner. Incubation with tretinoin caused a significant decrease in clonogenic survival of HT-3 and Caski cells compared with the control cultures. The invasive potential of HT-3 cells was decreased to 18%, whereas that of Caski cells to 21% on treatment with 8 µM concentration of tretinoin. In HT-3 cells, tretinoin treatment led to a prominent reduction in p-focal adhesion kinase (FAK), matrix metalloproteinases (MMP)-2, and MMP-9 expression in HT-3 cells. Treatment of the cervical cancer mice model with tretinoin led to a prominent decrease in tumor growth. The metastasis of tumor in model cervical cancer mice group was effectively inhibited in spleen, intestines, and peritoneal cavity. In silico studies showed that tretinoin interacts with alanine, proline, isoleucine, and glycine amino acid residues of FAK protein to block its activation. The 2-dimensional diagram of interaction of tretinoin with FAK protein revealed that tretinoin binds to alanine and glycine amino acids through conventional hydrogen bonding. CONCLUSION: In summary, tretinoin suppressed the proliferation, colony formation, and invasiveness of cervical cancer cells in vitro. It decreased the expression of activated focal adhesion kinase, MMP-2, and MMP-9 in HT-3 cells in dose-dependent manner. In silico studies showed that tretinoin interacts with alanine and glycine amino acids through conventional hydrogen bonding. In vivo data demonstrated that treatment of the cervical cancer mice model with tretinoin led to a prominent decrease in tumor growth. Therefore, tretinoin can be developed as an effective therapeutic agent for cervical cancer treatment.

Clinical and genomic characterization of an ATRA-insensitive acute promyelocytic leukemia variant with a FNDC3B::RARB fusion.

The promyelocytic leukemia-retinoic acid receptor-α (PML::RARA) fusion is the hallmark of acute promyelocytic leukemia (APL) and is observed in over 95% of APL cases. RARA and homologous receptors RARB and RARG are occasionally fused to other gene partners, which differentially affect sensitivity to targeted therapies. Most APLs without RARA fusions have rearrangements involving RARG or RARB, both of which frequently show resistance to all-trans-retinoic acid (ATRA) and/or multiagent chemotherapy for acute myeloid leukemia (AML). We present a 13-year-old male diagnosed with variant APL with a novel FNDC3B::RARB in-frame fusion that showed no response to ATRA but responded well to conventional AML therapy. While FNDC3B has been identified as a rare RARA translocation partner in ATRA-sensitive variant APL, it has never been reported as a fusion partner with RARB and it is only the second known fusion partner with RARB in variant APL. We also show that this novel fusion confers an RNA expression signature that is similar to APL, despite clinical resistance to ATRA monotherapy.

A Life-Threatening Complication During the Fourth Pregnancy Due to Acute Promyelocytic Leukemia: A Case Report.

Incidents of leukemia in pregnancy are infrequent with only one case found from 75,000 to 100,000 pregnancies. The pathophysiological mechanism of leukemia during pregnancy is still unclear. Leukemia which occurs in pregnancy is usually acute and predominantly the myeloid type.A 35-year-old woman in her fourth pregnancy with a gestational age of 38-39 weeks, came to the emergency department (ED) with complaints of contractions since 4.5 hours before admission. The contraction was not accompanied by discharge, mucus, or blood, and fetal movements was still active. She denied complaints of fever, nausea, vomiting, dizziness, shortness of breath, weakness, fatigue, lethargy, and bleeding. Physical examination results, both palpebral conjunctiva were pale. Laboratory examination results of a complete blood count, white blood cell count were 2,930/uL, hemoglobin 8.3 g/dL, Hct 24.10%, erythrocytes 2.78x106/µL, platelets 62,000/µL. Bone Marrow Aspiration (BMA) revealed Acute Promyelocytic Leukemia (APL).APL is a subtype of Acute Myelogenous Leukemia (AML). Persistent fatigue, recurrent infections, and bleeding are common manifestations of APL. The diagnosis of APL is made by bone marrow aspiration examination, and it is safe for pregnancy. APL therapy in pregnancy uses All-Trans Retinoic Acid (ATRA) and Arsenic Trioxide (ATO). ATRA and ATO are highly teratogenic, but recent studies have reported no fetal abnormalities.Accuracy and speed in diagnosing and initiating APL therapy in pregnancy are essential in preventing serious complications.