Metabolic flexibilities and vulnerabilities in the pentose phosphate pathway of the zoonotic pathogen Toxoplasma gondii.

Metabolic pathways underpin the growth and virulence of intracellular parasites and are therefore promising antiparasitic targets. The pentose phosphate pathway (PPP) is vital in most organisms, providing a reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) and ribose sugar for nucleotide synthesis; however, it has not yet been studied in Toxoplasma gondii, a widespread intracellular pathogen and a model protozoan organism. Herein, we show that T. gondii has a functional PPP distributed in the cytoplasm and nucleus of its acutely-infectious tachyzoite stage. We produced eight parasite mutants disrupting seven enzymes of the PPP in T. gondii. Our data show that of the seven PPP proteins, the two glucose-6-phosphate dehydrogenases (TgG6PDH1, TgG6PDH2), one of the two 6-phosphogluconate dehydrogenases (Tg6PGDH1), ribulose-5-phosphate epimerase (TgRuPE) and transaldolase (TgTAL) are dispensable in vitro as well as in vivo, disclosing substantial metabolic plasticity in T. gondii. Among these, TgG6PDH2 plays a vital role in defense against oxidative stress by the pathogen. Further, we show that Tg6PGDH2 and ribulose-5-phosphate isomerase (TgRPI) are critical for tachyzoite growth. The depletion of TgRPI impairs the flux of glucose in central carbon pathways, and causes decreased expression of ribosomal, microneme and rhoptry proteins. In summary, our results demonstrate the physiological need of the PPP in T. gondii while unraveling metabolic flexibility and antiparasitic targets.

Association between weight-adjusted waist index and testosterone deficiency in adult American men: findings from the national health and nutrition examination survey 2013-2016.

BACKGROUND: Testosterone deficiency (TD) and obesity are globally recognized health concerns, with a bidirectional causal relationship between them. And a newly discovered obesity indicator, the Weight-Adjusted-Waist Index (WWI), has been proposed, demonstrating superior adiposity identification capability compared to traditional body mass index (BMI) and waist circumference (WC) indicators. Therefore, we present the inaugural investigation into the associations of WWI with total testosterone levels and the risk of TD. METHODS: Data restricted to the National Health and Nutrition Examination Survey (NHANES) between 2013 and 2016 were analyzed. Only males aged > 20 years who completed body measures and underwent serum sex hormone testing were potentially eligible for analysis. Weighted multivariable linear regression and logistic regression analyses were employed to investigate the relationships between WWI and total testosterone levels, and the risk of TD, respectively. Smooth curve fittings and weighted generalized additive model (GAM) regression were conducted to examine the linear relationship among them. Additionally, subgroup analyses with interaction tests were performed to assess the stability of the results. RESULTS: Finally, a total of 4099 participants with complete data on testosterone and WWI were included in the formal analysis. The mean age of study participants was 46.74 ± 0.35 years with a TD prevalence of 25.54%. After adjusting all potential confounders, the continuous WWI displayed a negative linear relationship with total testosterone levels (ß=-61.41, 95%CI: -72.53, -50.29, P < 0.0001) and a positive linear relationship with risk of TD (OR = 1.88, 95%CI: 1.47, 2.39, P < 0.0001). When WWI was transformed into quartiles as a categorical variable, participants in Q4 exhibited lower total testosterone levels (ß=-115.4, 95%CI: -142.34, -88.45, P < 0.0001) and a higher risk of TD (OR = 3.38, 95% CI: 2.10, 5.44, P < 0.001). These associations remained stable in subgroup analyses without significant interaction (all P for interaction > 0.05). CONCLUSIONS: This investigation firstly unveiled a negative linear association between WWI and total testosterone levels, coupled with a positive linear relationship with the prevalence of TD in U.S. male adults aged 20 years and older. Further studies are needed to validate the potential utility of WWI for the early identification and timely intervention of TD.

Seroprevalence and risk factors of Toxoplasma gondii in urban cats from China.

BACKGROUND: Toxoplasma gondii infects almost all warm-blooded animals, and cats play a crucial role in the epidemiology of T. gondii as the definitive host. Despite sporadic reports on the seroprevalence of T. gondii in domestic cats, systematic surveys are lacking and some regions remain in China uninvestigated. METHODS: A total of 1,521 serum samples were collected from 10 regions of China and analyzed by antibodies against T. gondii by ELISA with the purpose of identifying risk factors of T. gondii infection in cats across China and obtaining seroprevalence data from some previously uninvestigated areas. RESULTS: Antibodies to T. gondii were detected in 62 of 1,478 (4.2%) urban pet cats and in 9 of 43 (20.9%) stray cats. Among the regions examined, the prevalence was 13% in Sichuan, 12.8% in Chongqing, 6.4% in Hunan, 2.5% in Hubei and 0.9% in Guangdong. Additionally, this is the first report on the seroprevalence of T. gondii in urban pet cats from Qinghai (6.2%), Anhui (3.1%), Jiangxi (2.5%), Shaanxi (2.4%) and Ningxia (1.6%). The age and lifestyle (stray or pet) of cats were identified as the risk factors for seropositivity by multivariate analysis of the data. CONCLUSIONS: Our findings improve our understanding of seroprevalence and risk factors of T. gondii infection in cats across China, and provide useful information for the formulating of preventive and control measures against this widespread zoonotic parasite.

Pulmonary manifestations of Erdheim-Chester disease: clinical characteristics, outcomes and comparison with Langerhans cell histiocytosis.

Erdheim-Chester disease (ECD) is a rare form of non-Langerhans cell histiocytosis that typically affects many organs, including the lung and pleura. However, there are few studies concerning pulmonary involvement in ECD patients, as well as the difference of pulmonary involvement between ECD and Langerhans cell histiocytosis (LCH). We performed a retrospective study of 54 ECD patients, and compared the pulmonary manifestations with those of adult LCH patients in our centre. The median age of diagnosis of the 54 ECD patients was 48 years (range 9-66 years). Chest computed tomography (CT) scans revealed lung involvement in 49 (91%) patients and pleural involvement in 34 (63%). Thirty-three (61%) patients had interstitial lung disease (ILD) with varying degrees of interlobular septal thickening, micronodules, and ground-glass opacities. ECD and LCH patients with pulmonary involvement showed significant differences in smoking status (P < 0·001), respiratory symptoms (P = 0·001) such as cough and pneumothorax (P < 0·001), and radiological findings, including cysts (P < 0·001), opacities (P < 0·001), and pleural thickening (P < 0·001). With a median follow-up duration of 24 months (range, 1-84 months), the estimated three-year overall survival (OS) of this entire ECD cohort was 90·2%. Patients with ILD tended to have worse progression-free survival (PFS) than those with no ILD (P = 0·29).

Increased activated regulatory T cell subsets and aging Treg-like cells in multiple myeloma and monoclonal gammopathy of undetermined significance: a case control study.

BACKGROUND: Accumulating evidence have indicated that regulatory T cells (Tregs) play an essential role in T cell-mediated immune response and development of multiple myeloma (MM). CD4+FoxP3+ T cells are composed of three phenotypically and functionally distinct subpopulations: CD45RA+FoxP3lo resting Tregs (rTregs), CD45RA-FoxP3hi activated Tregs (aTregs) and CD45RA-FoxP3lo non-suppressive T cells (non-Tregs). We aimed to clarify the frequency and function of these three subpopulations in newly diagnosed multiple myeloma and monoclonal gammopathy of undetermined significance (MGUS) patients. In addition, CD28-CD4+FoxP3+ Treg-like cell is a senescent regulatory T cell subset with partial suppressive function, which could be impaired during myelomagenesis. METHODS: we examined 20 patients with MGUS, 26 patients with newly diagnosed MM and 18 healthy volunteers. Flow cytometric analysis in peripheral blood and bone marrow was performed for frequency study. The immunosuppressive function of Treg subsets was assessed by their ability to suppress the proliferation of responder cells in co-culture. Concentration of cytokine from the culture supernatants of proliferation assay was measured using ELISA. RESULTS: The proportion of activated Tregs in CD4+ T cells was significantly higher in MGUS and MM patients than healthy controls (P = 0.01, P < 0.001) in both PB and BM; while the proportion of rTregs in MGUS, MM patients was significantly lower than that of controls (P = 0.02, P < 0.01) only in BM. There was no significant difference in frequencies of non-Tregs from MGUS to MM patients with normal controls (P = 0.14, P = 0.88). Significant increase in PB and BM Treg-like cells was observed in MGUS and MM cohort compared with healthy controls (P < 0.01, P < 0.01). Treg-like cells in MM patients were significantly higher than those in MGUS patients (P < 0.01). The inhibition rate of aTreg in bone marrow of MM patients was significantly higher than that of rTreg (P < 0.01), while the inhibition rate of non-Treg was significantly lower than that of rTreg cells (P < 0.01). Functional assays revealed the suppressive and secretory abilities of three Treg subsets were intact in MM patients. CONCLUSIONS: In summary, aTregs and aging Treg-like cells were quantitatively altered in MGUS and MM patients, which might be associated with disease progression and prognosis.

Bone marrow-derived mesenchymal stem cells increase drug resistance in CD133-expressing gastric cancer cells by regulating the PI3K/AKT pathway.

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are recruited to primary tumours to compose the tumour microenvironment. In various cancers, CD133-positive cells have been shown to possess cancer stem cell properties that confer chemoresistance. This study aimed to investigate the role of BM-MSCs in the anti-tumour drug resistance of CD133-expressing gastric cancer cells and explore the underlying mechanisms that governing this role. We found that CD133+ gastric cancer cells displayed more resistance to chemotherapeutics than CD133- cells. In addition, BM-MSCs increased the anti-apoptotic abilities and chemoresistance of CD133+ cells via upregulation of Bcl-2 and downregulation of BAX. Mechanistically, BM-MSCs triggered activation of the PI3K/Akt signalling cascade in CD133+ cells. Blocking the PI3K/Akt pathway inhibited the promotion of chemoresistance. Furthermore, BM-MSCs enhanced the drug resistance of CD133-overexpressing cells in vitro and in vivo, but not that of CD133-knockdown cells, which demonstrated the contribution of CD133 to this process. In conclusion, we demonstrated that BM-MSCs increased the anti-apoptotic abilities and drug resistance of CD133-expressing cells via activation of the PI3K/Akt pathway following Bcl-2 upregulation and BAX downregulation, in which CD133 played a significant role. Targeting this route may help improve the efficacy of chemotherapy in gastric cancer.

Causal effect of gut microbiota on the risk of prostatitis: a two-sample Mendelian randomization study.

BACKGROUND: Recent studies demonstrated that chronic prostatitis (CP) is closely related to the gut microbiota (GM). Nevertheless, the causal relationship between GM and CP has not been fully elucidated. Therefore, the two-sample Mendelian randomization (MR) analysis was employed to investigate this association. METHODS: The summary data of gut microbiota derived from a genome-wide association study (GWAS) involving 18,340 individuals in the MiBioGen study served as the exposure, and the corresponding summary statistics for CP risk, representing the outcome, were obtained from the FinnGen databases (R9). The causal effects between GM and CP were estimated using the inverse-variance weighted (IVW) method supplemented with MR-Egger, weighted median, weighted mode, and simple mode methods. Additionally, the false discovery rate (FDR) correction was performed to adjust results. The detection and quantification of heterogeneity and pleiotropy were accomplished through the MR pleiotropy residual sum and outlier method, Cochran's Q statistics, and MR-Egger regression. RESULTS: The IVW estimates indicated that a total of 11 GM taxa were related to the risk of CP. Seven of them was correlated with an increased risk of CP, while the remained linked with a decreased risk of CP. However, only Methanobacteria (OR 0.86; 95% CI 0.74-0.99), Methanobacteriales (OR 0.86; 95% CI 0.74-0.99), NB1n (OR 1.16; 95% CI 1.16-1.34), Methanobacteriaceae (OR 0.86; 95% CI 0.74-0.99), Odoribactergenus Odoribacter (OR 1.43; 95% CI 1.05-1.94), and Sutterellagenus Sutterella (OR 1.33; 95% CI 1.01-1.76) still maintain significant association with CP after FDR correction. Consistent directional effects for all analyses were observed in the supplementary methods. Subsequently, sensitivity analyses indicated the absence of heterogeneity, directional pleiotropy, or outliers concerning the causal effect of specific gut microbiota on CP (p > 0.05). CONCLUSION: Our study demonstrated a gut microbiota-prostate axis, offering crucial data supporting the promising use of the GM as a candidate target for CP prevention, diagnosis, and treatment. There is a necessity for randomized controlled trials to validate the protective effect of the linked GM against the risk of CP, and to further investigate the underlying mechanisms involved.

Don't wait any longer, conceive in time: a systematic review and meta-analysis based on semen parameters after varicocelectomy.

BACKGROUND: Varicocelectomy was considered to be beneficial to patients with varicocele-related infertility. However, there are only a few researchers who have explored the relationship between better timing and postoperative semen improvement in patients. METHODS: We conducted this meta-analysis by enrolling published prospective studies to find out the best waiting time after varicocelectomy to wait for better improvement of semen quality. An extensive search was conducted in PubMed, Web of Science, and Cochrane Library to identify eligible studies. The included studies were then analyzed comprehensively using STATA software and standardized mean differences (SMDs) and their corresponding 95% confidence intervals were calculated. RESULTS: Our comprehensive analysis showed that after varicocelectomy, follow-up results within 3 months or longer showed a significant improvement in semen parameters compared to the preoperative period. Notably, no further improvement in semen parameters was observed when the follow-up period reached six months or longer (semen volume: WMD: - 0.07 (- 0.29, 0.16); sperm concentration: WMD: - 1.33 (- 2.33, - 4.99); sperm motility: WMD: 2.31 (- 0.55, 5.18); sperm morphology: WMD: 1.29 (- 0.66, 3.24); sperm total motile count: WMD: 3.95 (- 6.28, 14.19)). CONCLUSIONS: Three months after varicocelectomy may be the optimal time for semen parameters compared to six months or even longer, which means it is also the preferable time for conception. However, more well-designed prospective studies are needed in the future to validate our conclusion.

Association between life's essential 8 and testosterone deficiency in US men: findings from national health and nutrition examination survey (NHANES) 2011-2016.

Background: Testosterone deficiency (TD) is closely associated with cardiovascular diseases (CVD). We intended to explore the association of Life's Essential 8 (LE8), the recently updated measurement of cardiovascular health, with the prevalence of TD among US male adults. Methods: The population-based cross-sectional study selected male adults aged 20 years or older from the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2016. According to the American Heart Association definitions, the LE8 score was measured on a scale of 0-100, and divided into health behavior and health factor scores, simultaneously. Furthermore, these scores were categorized into low (0-49), moderate (50-79), and high (80-100) classifications. TD is defined as a total testosterone level below 300ng/dL. Correlations were investigated by weighted multivariable logistic regression, and the robustness of the results were verified by subgroup analysis. Results: A total of 4971 male adults with an average age of 47.46 ± 0.41 years were eligible for the final analyses, of whom 1372 were determined to have TD. The weighted mean LE8 score of the study population was 68.11 ± 0.41. After fully adjusting potential confounders, higher LE8 scores were significantly associated with low risk of TD (odd ratio [OR] for each 10-point increase, 0.79; 95% CI, 0.71-0.88) in a linear dose-response relationship. Similar patterns were also identified in the association of health factor scores with TD (OR for each 10-point increase, 0.74; 95% CI, 0.66-0.83). These results persisted when LE8 and health factor scores was categorized into low, moderate, and high groups. The inversed association of LE8 classifications and TD remained statistically significant among older, obese, and men without CVD. Conclusions: LE8 and its health factor subscales scores were negatively associated with the presence of TD in linear fashions. Promoting adherence to optimal cardiovascular health levels may be advantageous to alleviate the burden of TD.

Metabolic plasticity, essentiality and therapeutic potential of ribose-5-phosphate synthesis in Toxoplasma gondii.

Ribose-5-phosphate (R5P) is a precursor for nucleic acid biogenesis; however, the importance and homeostasis of R5P in the intracellular parasite Toxoplasma gondii remain enigmatic. Here, we show that the cytoplasmic sedoheptulose-1,7-bisphosphatase (SBPase) is dispensable. Still, its co-deletion with transaldolase (TAL) impairs the double mutant's growth and increases 13C-glucose-derived flux into pentose sugars via the transketolase (TKT) enzyme. Deletion of the latter protein affects the parasite's fitness but is not lethal and is correlated with an increased carbon flux via the oxidative pentose phosphate pathway. Further, loss of TKT leads to a decline in 13C incorporation into glycolysis and the TCA cycle, resulting in a decrease in ATP levels and the inability of phosphoribosyl-pyrophosphate synthetase (PRPS) to convert R5P into 5'-phosphoribosyl-pyrophosphate and thereby contribute to the production of AMP and IMP. Likewise, PRPS is essential for the lytic cycle. Not least, we show that RuPE-mediated metabolic compensation is imperative for the survival of the ΔsbpaseΔtal strain. In conclusion, we demonstrate that multiple routes can flexibly supply R5P to enable parasite growth and identify catalysis by TKT and PRPS as critical enzymatic steps. Our work provides novel biological and therapeutic insights into the network design principles of intracellular parasitism in a clinically-relevant pathogen.

Role of 6-phosphogluconate dehydrogenase enzyme 1 in growth and virulence of Toxoplasma gondii and development of attenuated live vaccine.

Toxoplasma gondii is a ubiquitous pathogen that infects all warm-blooded animals, including humans, causing substantial socioeconomic and healthcare burdens. However, there is no ideal vaccine for toxoplasmosis. As metabolism is important in the growth and virulence of Toxoplasma, some key pathways are promising antiparasitic targets. Here, we identified 6-phosphogluconate dehydrogenase 1 (Tg6PGDH1) in the oxidative pentose phosphate pathway as a cytoplasmic protein that is dispensable for tachyzoite growth of T. gondii in vitro but critical for virulence and cyst formation in vivo. The depletion of Tg6PGDH1 causes decreased gene transcription involved in signal transduction, transcriptional regulation and virulence. Furthermore, we analysed the protective effect of the ME49Δ6pgdh1 mutant as an attenuated vaccine and found that ME49Δ6pgdh1 immunization stimulated strong protective immunity against lethal challenges and blocked cyst formation caused by reinfection. Furthermore, we showed that ME49Δ6pgdh1 immunization stimulated increased levels of interferon-gamma, tumour necrosis factor-alpha and Toxoplasma-specific IgG antibodies. These data highlight the role of Tg6PGDH1 in the growth and virulence of T. gondii and its potential as a target for the development of a live-attenuated vaccine.

Follicular helper T cell: Emerging roles in lymphomagenesis.

Follicular helper T cells (Tfh) are a subset of CD4+ T cells that are fundamental to forming germinal centers, which are the primary sites of antibody affinity maturation and the proliferation of activated B cells. Tfh cells have been extensively studied over the past 10 years, especially regarding their roles in cancer genesis. This review describes the characteristics of normal Tfh cells and focuses on the emerging link between Tfh cells and lymphomagenesis. Advances in lymphoma genetics have substantially expanded our understanding of the role of Tfh cells in lymphomagenesis. Moreover, we detail a range of agents and new therapies, with a major focus on chimeric antigen receptor T-cell therapy; these novel approaches may offer new treatment opportunities for patients with lymphomas.

Novel cellular immunotherapies for hematological malignancies: recent updates from the 2021 ASH annual meeting.

Cellular immunotherapy, including the chimeric antigen receptor T (CAR-T) cell therapy and CAR- natural killer (CAR-NK) cell therapy, has undergone extensive clinical investigation and development in recent years. CAR-T cell therapy is now emerging as a powerful cancer therapy with enormous potential, demonstrating impressive anti-tumor activity in the treatment of hematological malignancies. At the 2021 ASH annual meeting, numerous breakthroughs were reported concerning acute lymphocytic leukemia (ALL), lymphoma, acute myeloid leukemia (AML), and multiple myeloma (MM). Universal CAR-T cell and CAR-NK cell therapy, as well as induced pluripotent stem cell (iPSC)-derived immunotherapy, offer great "off-the-shelf" benefits. Major development and updates of cellular immunotherapy for hematological malignancies reported at the 2021 ASH annual meeting are summarized in this review.

Phase 2 study of oral thalidomide-cyclophosphamide-dexamethasone for recurrent/refractory adult Langerhans cell histiocytosis.

Langerhans cell histiocytosis (LCH) is a clonal histiocytic neoplasm with various clinical manifestations and heterogeneous prognoses. No standard therapy is available for recurrent/refractory LCH patients. This single-center, single-arm, phase 2 study enrolled 32 patients diagnosed with recurrent/refractory LCH. The TCD regimen (thalidomide 100 mg daily, cyclophosphamide 300 mg/m2 Day 1, 8, 15, and dexamethasone 40 mg Day 1, 8, 15, 22 every 4 weeks) was administered for 12 cycles and thalidomide alone as maintenance for 12 months. The primary endpoint was event-free survival (EFS). Events were defined as progression during or after TCD therapy or death from any cause. After a median follow-up of 22 months (range 5-24 months), no patient died of all causes. The overall response rate was 87.5%, including 18 patients (56.3%) achieving complete remission and 10 patients (31.3%) as partial remission. The estimated 24-month EFS was 64.0%. Patients with risk organ involvement had similar EFS compared to patients without risk organ involvement (P = 0.38). The common toxicities of TCD regimen include grade 1-2 neutropenia (18.8%), grade 1-2 constipation (12.5%), grade 1-2 tiredness (9.4%) and grade 2 peripheral neuropathy (12.5%). Oral thalidomide, cyclophosphamide and dexamethasone are effective and safe regimen for recurrent/refractory LCH patients, particularly for patients with risk organ involvement.

Effective treatment of progressive nodular histiocytosis by intermediate-dose cytarabine: a case report and literature review.

BACKGROUND: Progressive nodular histiocytosis (PNH) is a rare, clinically distinct non-Langerhans cell histiocytic neoplasm affecting the skin and mucous membranes with no signs of spontaneous regression of the lesions. Patients typically have hundreds of lesions of superficial xanthomatous papules to nodules and deep larger fibrous nodules, which can be life-threatening if laryngeal mucosa was involved. So far, few cases of PNH have been reported and no effective treatment has been shown to reverse the progressive clinical course. CASE PRESENTATION: Here we describe a case of PNH presenting as diffuse, progressively enlarging papules, nodules and even leonine appearance in a young woman. The diagnosis was confirmed by histological and immunohistochemical findings. Next-generation sequencing (NGS) showed identical missense mutation in XIAP Y404C and in-frame deletion in MAPK1 A2[6>5]. Since ERK inhibitor has not been on the market yet, the patient received chemotherapy instead. Traditional chemotherapy with intermediate-dose of cytarabine (500 mg/m2 cytarabine by 3-hour infusion every 12 hours for 3 days every 5 weeks) achieved favorable therapeutic effect as confirmed by clinical symptoms and PET/CT imaging. CONCLUSIONS: PNH is a rare, proliferative disorder with disfiguring lesions and deteriorative quality of life. Mutations in MAPK1, XIAP may play crucial roles in the pathogenesis of PNH. Intermediate-dose cytarabine can be considered as a promising treatment option for PNH patients.

Influence of poly(lactide) stereocomplexes as nucleating agents on the crystallization behavior of poly(lactide)s.

The influence of the addition of linear and four-arm poly(lactide) (PLA) stereocomplexes (scPLAs) on the non-isothermal and isothermal crystallization behavior of poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) from the molten state was investigated. The linear PLAs and four-arm PLA with a similar chain length for each arm were synthesized by ring-opening polymerization. The linear and four-arm scPLAs were then prepared by solution blending and characterized by 1H-NMR, FTIR, and WAXD analysis. Various mass ratios of the scPLAs were subsequently added to PLLA and PDLA as nucleating agents and specimens were prepared by solution casting. The isothermal and non-isothermal crystallization behavior of the specimens was examined by differential scanning calorimetry and polarized optical microscopy. The SC crystallites effectively promoted the nucleation of the PLAs, thereby increasing the general crystallization rate of the matrix. A 10% content of stereocomplex nucleating agent increased the crystallization rate of PDLA and PLLA by more than 55% and 70%, respectively. Compared with the linear scPLA, the four-arm scPLA more strongly promoted crystallization at higher temperatures. This might be because the greater degree of branching and larger steric hindrance of the four-arm scPLA led to the formation of defective SC crystallites, which was more beneficial for adsorption of the matrix on the crystal surface and permitted the nucleation and growth at higher temperatures. These results demonstrate that scPLAs can potentially be used as nucleating agents to improve the performance and transparency of PLA films.

Early or deferred treatment of smoldering multiple myeloma: a meta-analysis on randomized controlled studies.

PURPOSE: Smoldering multiple myeloma (SMM) is a rare asymptomatic plasma cell disorder. Even with emerging therapeutic approaches and risk stratification, the optimal time to treat SMM remains controversial. This meta-analysis aimed to compare early treatment with deferred treatment of SMM, especially high-risk SMM. METHODS: Early treatment was defined as treatment immediately after diagnosis. Deferred treatment was initiated after progression. The primary outcome was progression. Secondary outcomes were mortality, response, and safety. PubMed, EMBASE, Medline, Cochrane, and ClinicalTrials.gov databases were searched from January 1990 to March 2019. Randomized controlled trials (RCTs) comparing early treatment with deferred treatment in SMM patients were eligible. Risk ratios (RRs) with 95% confidence interval (CI) were pooled. RESULTS: Eight RCTs covering 885 SMM patients were included. Considering all the different treatment approaches, early treatment significantly decreased progression of SMM (RR=0.53, 95% CI 0.33-0.87, P=0.01). In subgroup analysis, melphalan plus prednisone (RR=0.22, 95% CI 0.08-0.64, P=0.005) and immuno-modulatory drugs (RR=0.43, 95% CI 0.31-0.59, P<0.00001) significantly reduced progression. However, neither mortality nor response rate was significantly affected by early treatment. In terms of high-risk SMM patients, early treatment significantly decreased both progression (RR=0.51, 95% CI 0.37-0.70, P=0.0001) and mortality (RR=0.53, 95% CI 0.29-0.96, P=0.04). Frequently seen adverse events were infection, constipation, asthenia, and second primary malignancy. A remarkably elevated risk of constipation was associated with early treatment using immuno-modulatory agents (RR=4.43, 95% CI 2.14-9.12, P<0.0001). Second primary malignancy was significantly increased with early treatment (RR=4.13, 95% CI 1.07-15.97, P=0.04). No significant difference was identified in infection or asthenia. CONCLUSION: These findings suggest that early treatment could decrease progression and mortality of high-risk SMM patients with a tolerable safety profile.