Volume 05 · Issue 02 · 2023

Programmed death-ligand 1 (PD-L1), expressed on the surface of tumor cells, can bind to programmed cell death-1 (PD-1) on T cells. The interaction of PD-1 and PD-L1 can inhibit T-cell responses by decreasing T-cell activity and accelerating their apoptosis. Various cancers express high levels of PD-L1 and exploit PD-L1/PD-1 signaling to evade T-cell immunity, and immunotherapies targeting the PD-1/PD-L1 axis have been shown to exert remarkable anti-tumor effects; however, not all tumor patients benefit from these therapies. Therefore, study of the mechanisms regulating PD-L1 expression are imperative. In this review, we explore regulation of PD-L1 expression in the contexts of gene transcription, signaling pathways, histone modification and remodeling, microRNAs, long noncoding RNAs, and post-translational modification. Current developments in studies of agents that block PD-L1 and correlations between immunotherapies targeting PD-1/PD-L1 and PD-L1 expression are also summarized. Our review will assist in understanding of PD-L1 expression regulation and discusses the implications of reported findings in cancer diagnosis and immunotherapy.

Patients with double-mutated CEBPA (CEBPAdm) AML were stratified into favorable risk group, however, few studies have investigated the heterogeneity of different CEBPAdm types in detail. In this study, we analyzed 2211 newly diagnosed AML and identified CEBPAdm in 10.8% of the patients. Within the CEBPAdm cohort, 225 of 239 patients (94.14%) presented with bZIP region mutations (CEBPAdmbZIP) while 14 of 239 patients (5.86%) without bZIP region mutation (CEBPAdmnonbZIP). Analysis of the accompanied molecular mutations showed statistically different incidences of GATA2 mutations between the CEBPAdmbZIP group and the CEBPAdmnonbZIP group (30.29% vs 0%). In the analysis of outcomes, patients with CEBPAdmnonbZIP were associated with shorter overall survival (OS) censored at hematopoietic stem cell transplantation (HSCT) during CR1 compared to those with CEBPAdmbZIP (hazard ratio (HR) = 3.132, 95% confidence interval (CI)= 1.229-7.979, P= .017). Refractory or relapsed AML (R/RAML) patients with CEBPAdmnonbZIP were associated with shorter OS compared to those with CEBPAdmbZIP (HR = 2.881, 95% CI = 1.021-8.131, P = .046). Taken together, AML with CEBPAdmbZIP and CEBPAdmnonbZIP showed different outcomes and might be regarded as distinctive AML entities.

Invasive fungal diseases (IFDs) are major and lethal infectious complications for patients with neutropenia after chemotherapy. Prophylaxis with intravenous and oral suspended itraconazole (200 mg Q12h intravenously × 2 days followed by 5 mg/kg·d orally in twice) or oral suspension of posaconazole (200 mg Q8h) was administered for preventing IFDs. The only 2 episodes of proven IFDs were not included after propensity-score matching (PSM), while the incidence of possible IFDs was 8.2% (9/110) in itraconazole group and 1.8% (2/110) in posaconazole group, respectively (P = .030). In clinical failure analysis, the failure rate of posaconazole group was lower as compared to the itraconazole group (2.7% vs 10.9%, P = .016). Both intravenous-oral itraconazole and posaconazole suspension are effective in preventing IFDs, while posaconazole suspension seems more tolerable.

Giant inclusions and Auer bodies in promyeloblasts were investigated in a study which included transmission electron microscopy (TEM) for morphology and ultrastructural cytochemistry for myeloperoxidase in 10 patients with acute promyelocytic leukemia (APL). Ultrastructural cytochemistry demonstrated positive myeloperoxidase reactivity in giant inclusions, expanded rER cisternae, Auer bodies and primary granules. TEM revealed that giant inclusions were adorned by degenerated rER membrane, some of them sharing features with Auer bodies. We hypothesize a novel origin for Auer body development in promyeloblasts of APL, namely that they originate from peroxidase-positive and expanded rER cisternae, and that primary granules were directly released from these expanded rER elements, bypassing the Golgi apparatus.

Rituximab maintenance (RM) prolongs the progression-free survival (PFS) of responding patients with follicular lymphoma (FL), but the maintenance efficacy in different Follicular Lymphoma International Prognostic Index (FLIPI) risk group is still confusing. We performed a retrospective analysis of the effect of RM treatments in patients with FL responding to induction therapy based on their FLIPI risk assessment carried out prior to treatment. We identified 93 patients between 2013 and 2019 who received RM every 3 months for ≥4 doses (RM group), and 60 patients who did not accept RM or received rituximab less than 4 doses (control group). After a median follow-up of 39 months, neither median overall survival (OS) nor PFS was reached for the entire population. The PFS was significantly prolonged in the RM group compared to the control group (median PFS NA vs 83.1 months, P = .00027). When the population was divided into the 3 FLIPI risk groups, the PFS differed significantly (4-year PFS rates, 97.5% vs 88.8% vs 72.3%, P = .01) according to group. There was no significant difference in PFS for FLIPI low-risk patients with RM compared to the control group (4-year PFS rates, 100% vs 93.8%, P = .23). However, the PFS of the RM group was significantly prolonged for FLIPI intermediate-risk (4-year PFS rates, 100% vs 70.3%, P = .00077) and high-risk patients (4-year PFS rates, 86.7% vs 57.1%, P = .023). These data suggest that standard RM significantly prolongs the PFS of patients assigned to intermediate- and high-risk FLIPI groups but not to low-risk FLIPI group, and pending larger-scale studies to validate.

Rothmund-Thomson syndrome (RTS) is a rare autosomal-recessive disorder with clinical features consisting of rash, poikiloderma, sparse hair, short stature, juvenile cataracts, skeletal abnormalities, and cancer predisposition. Genetic studies involving detection of pathogenic RECQL4 variants provide the diagnostic certitude. Osteosarcoma was found in two-thirds RECQL4-mutated RTS patients, while hematological malignancies were rarely reported. The variant diversity of RECQL4 gene has not been fully identified and mutations associated with hematologic malignancies are not well described. In this study, we presented a pedigree of RTS from a Chinese family, among which the proband was diagnosed with de novo myelodysplastic syndrome (MDS). Comprehensive medical examination and chromosome karyotyping were performed on the proband. Whole exome sequencing (WES) was performed on the proband, his sister and his mother. The familial cosegregation of sequence variants derived from WES was conducted by polymerase chain reaction-based Sanger sequencing. Structures of candidate RECQL4 mutants were done by in silico analysis to assess pathogenicity. Three novel RECQL4 germline variants, including c.T274C, c.G3014A, and c.G801C, were identified by WES and validated by Sanger sequencing. Prediction of conformation indicated that the structural stability of human RECQL4 protein was largely affected with these variants. The co-occurring U2AF1 p.S34F and TP53 p.Y220C mutations might contribute to the development of MDS. Our study expands the mutational spectrum of RECQL4 and provides underlying molecular mechanism for the development of MDS in RTS patients.

Hemochromatosis, either hereditary hemochromatosis (HH) or secondary hemochromatosis, consists of the accumulation of iron in the liver, heart, and other organs. It leads to end-organ damage in a proportion of affected subjects. Although liver-related morbidity (cirrhosis and hepatocellular carcinoma [HCC]) and mortality are well established, the frequency of these complications remains controversial. The aim of this study is to examine the rate of hospitalization and the incidence of iron overload-related comorbidities in patients with hemochromatosis between the years of 2002 and 2010. We queried the Nationwide Inpatient Sample (NIS) database from the year 2002 to 2010. We included adults (age ≥18 years) and used the ICD-CM 9 code 275.0x to identify hospitalized patients with a diagnosis of hemochromatosis. Data analysis for this study was generated using SAS software version 9.4. A total of 168,614 hospitalized patients between 2002 and 2010 had a diagnosis of hemochromatosis. The majority were males (57%) with a median age of 54 years (37-68), with a predominance of white patients (63.3%) followed by black (26.8%). The rate of hospitalization among patients with hemochromatosis increased by 79% between the years 2002 and 2010 (34.5/100,000 in 2002 vs 61.4/100,000 in 2010). The main associated diagnoses were diabetes mellitus (20.2%), cardiac disease, including arrhythmias (14%) and cardiomyopathy (dilated 3.8%; peri-, endo-, myocarditis 1.3%), liver cirrhosis (8.6%), HCC (1.6%), and acute liver failure (0.81%). Of note, HCC was associated with cirrhosis in 1188 patients (43% of HCC patients) and male sex (87%). Diagnostic biopsies were performed in 6023 (3.6%) of those patients and liver transplant was performed in 881 (0.5%). In-hospital mortality occurred in 3638 (2.16%) patients. In this large database study, we found a rising trend in hospitalization for hemochromatosis, possibly due to the increased recognition of this entity and billing for the condition. The incidence of cirrhosis in hemochromatosis was found to be similar to other studies (8.6% vs 9%). However, the rate of HCC was lower than previous reports (1.6% vs 2.2%-14.9%), and only 43% of HCC was associated with cirrhosis. This raises important pathophysiologic questions regarding the impact of iron overload in HCC. There has been an increase in the rate of hospitalization for patients with a diagnosis of hemochromatosis. This may be related to an increased recognition of hemochromatosis as the underlying etiology for conditions such as diabetes, cardiomyopathy, cirrhosis, and HCC. Further prospective studies are needed to clarify the burden of liver disease in HH and secondary iron overload.

Leukemia stem cells in acute myeloid leukemia (AML) can persist within unique bone marrow niches similar to those of healthy hematopoietic stem cells and resist chemotherapy. In the context of AML, endothelial cells (ECs) are crucial components of these niches that appear to promote malignant expansion despite treatment. To better understand these interactions, we developed a real-time cell cycle-tracking mouse model of AML (Fucci-MA9) with an aim of unraveling why quiescent leukemia cells are more resistant to chemotherapy than cycling cells and proliferate during disease relapse. We found that quiescent leukemia cells were more prone to escape chemotherapy than cycling cells, leading to relapse and proliferation. Importantly, post-chemotherapy resting leukemia cells tended to localize closer to blood vessels. Mechanistically, after chemotherapy, resting leukemia cells interacted with ECs, promoting their adhesion and anti-apoptotic capacity. Further, expression analysis of ECs and leukemia cells during AML, after chemotherapy, and after relapse revealed the potential of suppressing the post-chemotherapy inflammatory response to regulate the functions of leukemia cells and ECs. These findings highlight the role of leukemia cells in evading chemotherapy by seeking refuge near blood vessels and provide important insights and directions for future AML research and treatment.