Efficacy and safety of ibrutinib in diffuse large B-cell lymphoma: A single-arm meta-analysis

Bruton's Tyrosine Kinase Inhibitors in Refractory or Relapsing Primary Central Nervous System Lymphoma: A Meta-analysis and Systematic Review

BACKGROUND

Primary central nervous system lymphoma (PCNSL) is an aggressive lymphoma that primarily affects the central nervous system. Current treatments, such as surgery, chemotherapy, and whole-brain radiotherapy, often fail to achieve satisfactory results. The prognosis for patients with refractory or relapsed (R/R) PCNSL is bleak. The optimal treatment for refractory or relapsed PCNSL is poorly defined due to a limited number of studies in this setting. Bruton's tyrosine kinase (BTK) inhibitors, as part of targeted therapy regimens, have undergone testing in several clinical trials against PCNSL and have shown promising results in the treatment of R/R PCNSL. In this meta-analysis, we aim to explore and critically appraise the evidence regarding the efficacy of BTK inhibitors in the treatment of refractory or relapsed PCNSL.

METHODS

A systematic search was conducted on multiple databases including PubMed, Embase, Cochrane library, Wanfang Data Knowledge Service Platform, and CNKI, covering the period up to November 2023. The inclusion criteria for studies were patients with R/R PCNSL who received BTK inhibitors, and reported data on overall response rate (ORR) and complete remission (CR). The pooled rates were calculated using a random-effects or fixed-effects model with a double arcsine transformation, and 95% CIs were determined for all outcomes.

RESULTS

In total, 1 studies involving 185 patients were identified and included in the meta-analysis. The pooled complete remission (CR) rate of BTK inhibitors-based treatment for R/R PCNSL was found to be 50%. Subgroup analysis revealed that the CR rates for BTK inhibitor monotherapy, BTK inhibitor combined with chemotherapy, and BTK inhibitor combined with radiotherapy for R/R PCNSL were 7%, 68%, and 80%, respectively. The ORR for BTK inhibitors-based treatment for R/R PCNSL was 70%. Subgroup analysis showed that the ORR rates for BTK inhibitor monotherapy and BTK inhibitor combined with chemotherapy for R/R PCNSL were 55% and 83%, respectively. The most common adverse events (AEs) reported were hematologic AEs, including neutropenia, anemia, and thrombocytopenia. Severe nonhematologic AEs included rash, febrile neutropenia, increased levels of aspartate aminotransferase, and increased blood bilirubin.

CONCLUSIONS

BTK inhibitors can be regarded as a safe and effective treatment option for R/R PCNSL, thereby providing a potential new avenue for R/R PCNSL treatment. However, it is important to note that further large-sample prospective randomized controlled trials are needed to validate these findings and establish their wider applicability.

T Cells Spatially Regulate B Cell Receptor Signaling in Lymphomas through H3K9me3 Modifications

Activated B cell-like diffuse large B-cell lymphoma (ABC-DLBCL) is a subtype associated with poor survival outcomes. Despite identifying therapeutic targets through molecular characterization, targeted therapies have limited success. New strategies using immune-competent tissue models are needed to understand how DLBCL cells evade treatment. Here, synthetic hydrogel-based lymphoma organoids are used to demonstrate how signals in the lymphoid tumor microenvironment (Ly-TME) can alter B cell receptor (BCR) signaling and specific histone modifications, tri-methylation of histone 3 at lysine 9 (H3K9me3), dampening the effects of BCR pathway inhibition. Using imaging modalities, T cells increase DNA methyltransferase 3A expression and cytoskeleton formation in proximal ABC-DLBCL cells, regulated by H3K9me3. Expansion microscopy on lymphoma organoids reveals T cells increase the size and quantity of segregated H3K9me3 clusters in ABC-DLBCL cells. Findings suggest the re-organization of higher-order chromatin structures that may contribute to evasion or resistance to therapy via the emergence of novel transcriptional states. Treating ABC-DLBCL cells with a G9α histone methyltransferase inhibitor reverses T cell-mediated modulation of H3K9me3 and overcomes T cell-mediated attenuation of treatment response to BCR pathway inhibition. This study emphasizes the Ly-TME's role in altering DLBCL fate and suggests targeting aberrant signaling and microenvironmental cross-talk that can benefit high-risk patients.

Metronomic chemotherapy in hematology: Lessons from preclinical and clinical studies to build a solid rationale for future schedules

Metronomic chemotherapy (mCHEMO), based on frequent, regular administration of low, but pharmacologically active drug doses, optimizes antitumor efficacy by targeting multiple targets and reducing toxicity of antineoplastic drugs. This minireview will summarize preclinical and clinical studies on cytotoxic drugs given at weekly, daily, or at continuous metronomic schedules alone or in combination with novel targeted agents for hematological malignancies, including lymphoma, multiple myeloma, and leukemia. Most of the preclinical in vitro and in vivo studies have reported a significant benefit of both mCHEMO monotherapy and combinatorial regimens compared with chemotherapy at the maximum tolerated dose. However, the combination of mCHEMO with targeted drugs is still little explored in the hematologic clinical setting. Data obtained from preclinical studies on low dose metronomic chemotherapy in hematological malignancies clearly suggested the possibility to clinically investigate more tolerable and effective strategies for the treatment of patients with advanced hematological malignancies, or at least for those frail and elderly patients, who are not eligible or resistant to standard treatments.

Efficacy and safety of small-incision corneal intrastromal lenticule implantation for hyperopia correction: a systematic review and meta-analysis

Purpose

To assess the efficacy and safety of intrastromal lenticule implantation for the treatment of hyperopia.

Methods

A systematic search of PubMed, Web of Science, Embase, Cochrane Library, China National Knowledge Internet, and Wan Fang Database identified studies on small-incision intrastromal lenticule implantation for hyperopia correction until January 2023. The Joanna Briggs Institute (JBI) critical appraisal tool was used to assess the quality of the retrospective research, and the Methodological Index for Non-randomized Studies (MINORS) was used to assess the quality of the prospective research. This study included postoperative visual outcomes, corneal morphology, and biomechanical outcomes.

Results

A total of 456 articles were identified, of which 10 were included in the meta-analysis. Ten single-arm studies involving 190 eyes were included. A meta-analysis demonstrated that corneal intrastromal lenticule implantation treatment significantly improved hyperopia. Uncorrected distance visual acuity (UDVA) significantly improved compared to the preoperative value (p = 0.027), corrected distance visual acuity showed no difference compared to the preoperative value (p = 0.27), and 87% eyes have no loss of one or more lines in the Snellen lines of CDVA (p < 0.00001). There was a significant difference between the spherical equivalent refractive (SE) and preoperative examination (p < 0.00001), 52% of eyes had ±0.5 diopters (D) postoperative SE (p < 0.00001), and 74% eyes had ±1.0 D postoperative SE (p < 0.00001). The central corneal thickness (CCT) increased by 72.68 μm compared to that preoperatively (p < 0.00001), and corneal curvature increased by 4.18D (p < 0.00001). The Q-value decreased by 0.82 (p < 0.00001), and higher-order aberration (HOA) decreased by 0.66 (p < 0.00001).

Conclusion

Small-incision intrastromal lenticule implantation may be an effective solution for correcting hyperopia. The effect of improved vision is significant, but further exploration is needed for changes in corneal biomechanics and long-term safety.Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42023432343.

Intrathecal or intraventricular antimicrobial therapy for post-neurosurgical Gram-negative bacillary meningitis or ventriculitis: a systematic review and meta-analysis

PURPOSE

Extensively-drug-resistant Gram-negative bacteria (XDR GNB)-related post-neurosurgical infection is closely related to mortality, which represents a major challenge for neurosurgeons. There is an urgent need to review and evaluate methods to reduce mortality.

METHODS

Both international and Chinese databases were searched independently from their inception to 15 June 2023. A meta-analysis was conducted using RevMan 5.4 to compare the efficacy and safety of intravenous (IV) treatment in combination with intrathecal or intraventricular (ITH/IVT) treatment with IV treatment alone for post-neurosurgical meningitis or ventriculitis due to GNB. Mortality, microbiological clearance and adverse events were considered as primary outcomes.

RESULTS

In total, 18 eligible studies involving 602 patients were included in the meta-analysis. The IV + ITH/IVT group was associated with significantly lower mortality (especially in the XDR GNB subgroup) and acceptable safety. In terms of microbiological clearance, a significant decrease was shown in the XDR GNB subgroup. Significant benefits were shown in laboratory parameters and clinical symptoms after patients were treated with ITH/IVT.

CONCLUSION

Additional ITH/IVT treatment may promote XDR GNB clearance and reduce mortality. In addition, ITH/IVT administration can improve clinical symptoms and cerebrospinal fluid indicators of patients with post-neurosurgical infections. Significantly, ITH/IVT treatment does not increase the incidence of adverse events at the recommended dose.

Efficacy and safety of Orelabrutinib-based regimens in diffuse large B-cell lymphoma: a single-center retrospective analysis

Currently, combining chemotherapy with Bruton tyrosine kinase inhibitors (BTKi) has demonstrated significant effectiveness in treating patients with diffuse large B-cell lymphoma. Orelabrutinib is a second-generation BTK inhibitor, and presently, there have been few reports of Orelabrutinib being used to treat DLBCL. We conducted a retrospective investigation to explore the safety and efficacy of Orelabrutinib in combination with chemotherapy or immunotherapy. The study comprised 19 patients with a median age of 61 years. The overall response rate (ORR) was 89.5% with a complete response (CR) rate of 73.7% and a partial response rate (PR) of 15.8%. The estimated 2-year overall survival (OS) and progression-free survival (PFS) rates were 78.6% (95%CI, 59.8%-100%) and 72.2% (95% CI, 52.4%-99.6%), respectively, with a median follow-up time of 11 months (range 2-24). The most prevalent grade 3 or 4 adverse events (AEs), neutropenia (52.6%), anemia (36.8%), thrombocytopenia (26.3%), febrile neutropenia (26.3%), and lung infection (10.5%), were the most common. Our results reveal that Orelabrutinib is an effective therapy for DLBCL patients. Furthermore, our first investigation of the Orelabrutinib application lays a foundation for larger retrospective studies.

miR-28-based combination therapy impairs aggressive B cell lymphoma growth by rewiring DNA replication

Diffuse large B cell lymphoma (DLBCL) is the most common aggressive B cell lymphoma and accounts for nearly 40% of cases of B cell non-Hodgkin lymphoma. DLBCL is generally treated with R-CHOP chemotherapy, but many patients do not respond or relapse after treatment. Here, we analyzed the therapeutic potential of the tumor suppressor microRNA-28 (miR-28) for DLBCL, alone and in combination with the Bruton's tyrosine kinase inhibitor ibrutinib. Combination therapy with miR-28 plus ibrutinib potentiated the anti-tumor effects of monotherapy with either agent by inducing a specific transcriptional cell-cycle arrest program that impairs DNA replication. The molecular actions of miR-28 and ibrutinib synergistically impair DNA replication by simultaneous inhibition of origin activation and fork progression. Moreover, we found that downregulation of the miR-28-plus-ibrutinib gene signature correlates with better survival of ABC-DLBCL patients. These results provide evidence for the effectiveness of a new miRNA-based ibrutinib combination therapy for DLBCL and unveil the miR-28-plus-ibrutinib gene signature as a new predictor of outcome in ABC-DLBCL patients.

Overcoming the therapeutic limitations of EZH2 inhibitors in Burkitt's lymphoma: a comprehensive study on the combined effects of MS1943 and Ibrutinib

Enhancer of zeste homolog 2 (EZH2) and Bruton's tyrosine kinase (BTK) are both key factors involved in the development and progression of hematological malignancies. Clinical studies have demonstrated the potential of various EZH2 inhibitors, which target the methyltransferase activity of EZH2, for the treatment of lymphomas. However, despite their ability to effectively reduce the H3K27me3 levels, these inhibitors have shown limited efficacy in blocking the proliferation of lymphoma cells. To overcome this challenge, we employed a hydrophobic tagging approach utilizing MS1943, a selective EZH2 degrader. In this study, we investigated the inhibitory effects of two drugs, the FDA-approved EZH2 inhibitor Tazemetostat, currently undergoing clinical trials, and the novel drug MS1943, on Burkitt's lymphoma. Furthermore, we assessed the potential synergistic effect of combining these drugs with the BTK inhibitor Ibrutinib. In this study, we evaluated the effects of combination therapy with MS1943 and Ibrutinib on the proliferation of three Burkitt's lymphoma cell lines, namely RPMI1788, Ramos, and Daudi cells. Our results demonstrated that the combination of MS1943 and Ibrutinib significantly suppressed cell proliferation to a greater extent compared to the combination of Tazemetostat and Ibrutinib. Additionally, we investigated the underlying mechanisms of action and found that the combination therapy of MS1943 and Ibrutinib led to the upregulation of miR29B-mediated p53-upregulated modulator of apoptosis PUMA, BAX, cleaved PARP, and cleaved caspase-3 in Burkitt's lymphoma cells. These findings highlight the potential of this innovative therapeutic strategy as an alternative to traditional EZH2 inhibitors, offering promising prospects for improving treatment outcomes in Burkitt's lymphoma.

Evidence of pre-approval clinical trial supporting the granted conditional approval for novel cancer drugs in China between 2015 and 2022

Background

Accelerated approval (AA) of novel anticancer drugs based on surrogacy has attracted considerable concern globally. China National Medical Products Administration (NMPA) also established a similar conditional approval (CA) program to accelerate the approval of novel drugs to address unmet medical needs. This cross-sectional study aimed to evaluate the pre-approval clinical trial evidence and potential challenge of cancer drugs receiving CA in China from policy implementation to 2022.

Methods

The cancer drugs (initial and supplemental indications) granted CA between January 1, 2015 and December 31, 2022 using the public database of the NMPA were analyzed. The characteristics of the cancer drugs received CA were described. Primary efficacy endpoints and safety derived from the pre-approval clinical trial, including response rates (RR), progression-free survival (PFS), overall survival (OS), treatment-related serious adverse events (SAE) and Grade ≥3 adverse events (AEs) were quantitatively estimated by meta-analysis. Besides, the correlation between the surrogate endpoints and OS was estimated by the reported trial-level correlation analysis.

Findings

The NMPA approved 72 cancer indications (56 new molecular entities) with CA between 2015 and 2022. 34 indications (47%) were also approved by the FDA or EMA. 74% (53/72) of cancer indications were based on a single-arm trial design while 26% (19/72) for randomized controlled trials. The pooled RR was 0.50 (95% CI: 0.45-0.55, I2 = 96%) with significant differences across cancer types and targets while the pooled hazard risk was 0.39 (95% CI: 0.28-0.53, I2 = 89%) for PFS and 0.67 (95% CI: 0.61-0.73, I2 = 0%) for OS. The pooled treatment-related SAE and Grade ≥3 AEs from single-arm designs resulted in 15% and 25%, respectively. In randomized controlled trials, the pooled treatment-related SAE and Grade ≥3 AEs observed in CA drugs and the control groups were comparable. Surrogate endpoints were widely used as the primary efficacy endpoints in the pre-approval pivotal clinical trials with 75% (54/72) for RR, 10% (7/72) for PFS, and 4% (3/72) for others. Of these, 27% (17/63) of the surrogate endpoints reported a trial-level correlation with OS; three reported high correlation (r ≥ 0.85), two reported moderate correlation (0.70 ≤ r < 0.85) and 12 reported low correlation (r < 0.70).

Interpretation

The majority of novel cancer drugs that received CA were based on RR designed for single-arm trials. The reported correlations of treatment effect between the surrogate endpoints and OS used for CA were limited. Our findings highlighted that the introduction of OS or quality of life based on RCT in confirmatory clinical trials as much as feasible was essential to ensure the clinical benefits for patients.

Funding

This study was supported by postdoctoral fellowship from Tsinghua-Peking Joint Centers for Life Sciences (CLS).

PD-L1 expression predicts efficacy in the phase II SPiReL trial with MVP-S, pembrolizumab, and low-dose CPA in R/R DLBCL

BACKGROUND

Patients with relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL) have limited treatment options.

METHODS

R/R DLBCL patients, who were mostly ineligible for ASCT due to age or comorbidities, were treated with maveropepimut-S (MVP-S, previously DPX-Survivac) a survivin directed T cell educating therapy, pembrolizumab, and intermittent low-dose cyclophosphamide.

FINDINGS

We identified, using univariate analysis, a subset of patients with enhanced ORR, PFS and DOR. Patients with baseline CD20+/PD-L1 expression had an ORR of 46% (6/13) and the disease control rate was 10/13 (77%). The PFS and OS of the positive CD20+/PD-L1 patients were 7.1 months and 17.4 months, whereas in the intent-to-treat (ITT) population of 25 enrolled patients, the ORR was 28% (7/25), median PFS and OS were 4.2 months and 10.1 months respectively. A total of 6/7 clinical responders occurred in CD20+/PD-L1 patients. The regimen was well-tolerated, requiring only minor dose modifications and one discontinuation. Grade 1 or 2 injection site reactions occurred in 14/25, (56%). Statistically significant associations were also seen between PFS and; injection site reactions; and ELISpot response to survivin peptides, both identifying the mechanistic importance of specific immune responses to survivin.

INTERPRETATION

This immunotherapy combination was found to be active and safe in this clinically challenging patient population.

Human amniotic membrane graft for refractory macular hole: A single-arm meta-analysis and systematic review

PURPOSE

The treatment of refractory macular holes is controversial, with human amniotic membrane grafts emerging recently as an attractive option. We performed a meta-analysis and systematic review in this paper to assess the results of human amniotic membrane (hAM) in the treatment of refractory macular hole (MH).

METHODS

We searched the Cochrane Database of Systematic Reviews, Web of Science, PubMed, Embase, China National Knowledge Infrastructure databases, VIP database, Wanfang Data Knowledge Service Platform, Sinomed, Chinese Clinical Trial Registry, and Clinical Trials.gov. Studies reporting hAM for the treatment of refractory MH were included. The outcomes are MH closure rate, visual acuity (VA) improvement rate, and graft dislocation/contracture rate.

RESULTS

A total of 8 studies on 103 eyes were included, all of which had undergone failed vitrectomy and internal limiting membrane (ILM) peeling. In all studies, the VA improvement rate was 66% (95%CI: 45 to 84%), the MH closure rate was 94% (95%CI: 84 to 100%) and the hAM graft dislocation/contracture rate was 6% (95%CI: 0 to 15%). In the studies using cryopreserved hAM grafts, the MH closure rate was 99% (95%CI: 94 to 100%) and the hAM graft dislocation/contracture rate was 3% (0%, 10%). The VA improvement rates were 94% (95%CI: 79 to 100%) in the retinal detachment subgroup, 37% (95%CI: 20 to 56%) in the pathologic myopia subgroup, and 62% (95%CI: 14 to 100%) in the idiopathic MH subgroup.

CONCLUSION

Human amniotic membrane in the treatment of refractory MH results in visual improvement. It has a high macular hole closure rate and low dislocation/contracture rate. Cryopreserved hAM grafts might have better outcomes than dehydrated grafts.

Drug-Resistance Mechanism and New Targeted Drugs and Treatments of Relapse and Refractory DLBCL

Diffuse large B-cell lymphoma (DLBCL) is the most common aggressive non-Hodgkin's lymphoma (NHL). 30 ~ 40% of DLBCL patients were resistant to the standard R-CHOP regimen or recurrence after remission. It is currently believed that drug resistance is the main cause of the recurrence and refractory of DLBCL (R/R DLBCL). With the increased understanding of DLBCL biology, tumor microenvironment and epigenetics, some new therapies and drugs like molecular and signal pathway target therapy, chimeric antigen receptor (CAR) T-cell therapy, immune checkpoint inhibitors, antibody drug-conjugate and tafasitamab have been used for R/R DLBCL. This article will review the drug resistance mechanism and novel targeted drugs and therapies of DLBCL.

Quantitative evaluation of therapy options for relapsed/refractory diffuse large B-cell lymphoma: A model-based meta-analysis

New therapies for relapsed/refractory diffuse large B-cell lymphoma (r/rDLBCL) have emerged in recent years, but there have been no comprehensive quantitative comparisons of the efficacy of these therapies. In this study, the efficacy characteristics of 11 types of treatment strategy and 63 treatment regimens were compared by model based meta-analysis. We found that compared with monotherapy, association therapy had significant benefits in terms of overall survival (OS), progression-free survival (PFS), and objective response rate (ORR). However, whereas treatment regimens involving chemotherapy contributed to significant improvements in ORR and PFS, OS was not improved. In terms of treatment strategy, we identified chemotherapy in association with immunotherapy sequential autologous stem cell transplantation (ASCT), the association of two different types of immunotherapies, chemotherapy sequential ASCT, chemotherapy in association with immunotherapy, and chemotherapy in association with two types of immunotherapies as showing better efficacy. With respect to specific treatment regimens, we found that the following had better efficacy: rituximab in association with inotuzumab ozogamicin; rituximab in association with carmustine, etoposide, cytarabine, and melphalan sequential ASCT (R-BEAM+ASCT); lenalidomide in association with rituximab, etoposide, cisplatin, cytarabine, and methylprednisolone; iodine-131 tositumomab in association with BEAM sequential ASCT; and chemotherapy sequential chimeric antigen receptor T-cell immunotherapy, with median OS of 48.2, 34.2, 27.8, 25.8, and 25 months, respectively. Moreover, with respect to association therapy, there was a strong correlation between the 6-month PFS and 2-year OS. The findings of this study provide the necessary quantitative information for clinical practice and clinical trial design for the treatment of r/rDLBCL.

Efficacy and safety of chimeric antigen receptor T-cells treatment in central nervous system lymphoma: a PRISMA-compliant single-arm meta-analysis

BACKGROUND

Chimeric antigen receptor (CAR) T cells are used to treat refractory and recurrent B-cell lymphoma. When administered intravenously, CAR T cells can be detected in cerebrospinal fluid, and thus represent a promising method for the treatment of central nervous system lymphoma (CNSL). This meta-analysis aimed to clarify the effectiveness and safety of CAR T-cell therapy in the treatment of CNSL.

METHODS

Studies involving patients with CNSL who received CAR T-cell therapy that reported overall response (OR), complete response (CR), and partial response (PR) were included. A random-effects or fixed-effects model with double arcsine transformation was used for the pooled analysis and 95% confidence intervals (CI) were determined for all outcomes.

RESULTS

Eight studies, comprising 63 patients, were identified and were included in the meta-analysis. The pooled OR and CR rates after treatment with CAR T cells were 69% (95% CI, 56-81%) and 51% (95% CI, 37-64%), respectively. The pooled rate of progressive disease after remission was 38% (95% CI, 21-55%). The pooled rate for neurotoxicity grade 3 or above was 12% (95% CI, 3-24%, I² = 0.00%, p = 0.53). No treatment-related deaths were reported.

CONCLUSIONS

CAR T-cell therapy is a promising option for the treatment of CNSL owing to a high short-term remission rate and controllable side effects. However, the high recurrence rate after remission must be addressed. Long-term follow-up data with large sample sizes are also needed to better assess the effectiveness and safety of CAR T-cell therapy.

REGISTRATION

This meta-analysis was registered in the international prospective register of systematic reviews (PROSPERO) (CRD42022301332).

Epidemiology and survival outcomes of patients with primary intraocular lymphoma: a population-based analysis

BACKGROUND

Primary intraocular lymphoma (PIOL) is a rare malignancy with a poor prognosis, but its optimal therapy remains unclear. Herein, we aimed to analyze the epidemiology and survival outcomes of PIOL patients based on a population-based cancer registry in the United States.

METHODS

Patients diagnosed with PIOL between 1992 and 2018 were identified from the Surveillance Epidemiology and End Results program. The patients were divided into two groups: those aged < 60 years and ≥ 60 years. We used the chi-squared test to analyze the differences between the two groups. Descriptive analyses were performed to analyze epidemiological characteristics and treatment. The likely prognostic factors were analyzed by Kaplan-Meier curves and Cox proportional hazards models.

RESULTS

The overall incidence of PIOL was 0.23/1,000,000, which was steadily increasing from 1992 to 2018, with an annual percentage change of 2.35. In total, 326 patients (mean age, 66.1 years) with PIOL were included in this study, 72.1% were aged ≥ 60 years, 84.4% were White, and 60.4% were female. The most common pathological type was diffuse large B-cell lymphoma (DLBCL), but in patients aged < 60 years, extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue was the most common. The disease-specific survival rates were 74.2% and 61.5% 5 and 10 years after diagnosis, respectively. Survival analysis found that surgery, radiation, and chemotherapy did not lead to better prognosis.

CONCLUSIONS

PIOL is a rare disease with poor prognosis, and its incidence has been increasing for nearly 30 years. It usually affects people aged ≥ 60 years, and DLBCL is the most common pathological type of PIOL. Patients aged < 60 years and with non-DLBCL type have improved survival. Survival of PIOL has improved in recent years.

Comparison of Intermolecular Interactions of Irreversible and Reversible Inhibitors with Bruton’s Tyrosine Kinase via Molecular Dynamics Simulations

Bruton’s tyrosine kinase (BTK) is a key protein from the TEC family and is involved in B-cell lymphoma occurrence and development. Targeting BTK is therefore an effective strategy for B-cell lymphoma treatment. Since previous studies on BTK have been limited to structure-function analyses of static protein structures, the dynamics of conformational change of BTK upon inhibitor binding remain unclear. Here, molecular dynamics simulations were conducted to investigate the molecular mechanisms of association and dissociation of a reversible (ARQ531) and irreversible (ibrutinib) small-molecule inhibitor to/from BTK. The results indicated that the BTK kinase domain was found to be locked in an inactive state through local conformational changes in the DFG motif, and P-, A-, and gatekeeper loops. The binding of the inhibitors drove the outward rotation of the C-helix, resulting in the upfolded state of Trp395 and the formation of the salt bridge of Glu445-Arg544, which maintained the inactive conformation state. Met477 and Glu475 in the hinge region were found to be the key residues for inhibitor binding. These findings can be used to evaluate the inhibitory activity of the pharmacophore and applied to the design of effective BTK inhibitors. In addition, the drug resistance to the irreversible inhibitor Ibrutinib was mainly from the strong interaction of Cys481, which was evidenced by the mutational experiment, and further confirmed by the measurement of rupture force and rupture times from steered molecular dynamics simulation. Our results provide mechanistic insights into resistance against BTK-targeting drugs and the key interaction sites for the development of high-quality BTK inhibitors. The steered dynamics simulation also offers a means to rapidly assess the binding capacity of newly designed inhibitors.

Evidence-based expert consensus on the management of primary central nervous system lymphoma in China

Primary central nervous system lymphoma (PCNSL) is a type of central nervous system restricted non-Hodgkin lymphoma, whose histopathological diagnosis is majorly large B cell lymphoma. To provide specific, evidence-based recommendations for medical professionals and to promote more standardized, effective and safe treatment for patients with PCNSL, a panel of experts from the Chinese Neurosurgical Society of the Chinese Medical Association and the Society of Hematological Malignancies of the Chinese Anti-Cancer Association jointly developed an evidence-based consensus. After comprehensively searching literature and conducting systematic reviews, two rounds of Delphi were conducted to reach consensus on the recommendations as follows: The histopathological specimens of PCNSL patients should be obtained as safely and comprehensively as possible by multimodal tomography-guided biopsy or minimally invasive surgery. Corticosteroids should be withdrawn from, or not be administered to, patients with suspected PCNSL before biopsy if the patient's status permits. MRI (enhanced and DWI) should be performed for diagnosing and evaluating PCNSL patients where whole-body PET-CT be used at necessary time points. Mini-mental status examination can be used to assess cognitive function in the clinical management. Newly diagnosed PCNSL patients should be treated with combined high-dose methotrexate-based regimen and can be treated with a rituximab-inclusive regimen at induction therapy. Autologous stem cell transplantation can be used as a consolidation therapy. Refractory or relapsed PCNSL patients can be treated with ibrutinib with or without high-dose chemotherapy as re-induction therapy. Stereotactic radiosurgery can be used for PCNSL patients with a limited recurrent lesion who were refractory to chemotherapy and have previously received whole-brain radiotherapy. Patients with suspected primary vitreoretinal lymphoma (PVRL) should be diagnosed by vitreous biopsy. PVRL or PCNSL patients with concurrent VRL can be treated with combined systemic and local therapy.

Interfering B cell receptor signaling via SHP-1/p-Lyn axis shows therapeutic potential in diffuse large B-cell lymphoma

Background

Diffuse large B cell lymphoma (DLBCL) is an aggressive and molecularly heterogeneous non-Hodgkin’s lymphoma. The B cell receptor (BCR) signaling pathway in DLBCL emerges as a new drug target. Protein phosphatase SHP-1 negatively regulates several oncogenic tyrosine kinases and plays a tumor suppressive role.

Methods

The direct SHP-1 agonists were used to evaluate the potential therapeutic implication of SHP-1 in DLBCL. Immunohistochemical staining for SHP-1 was quantified by H-score. The SHP-1 phosphatase activity was determined using tyrosine phosphatase assay. In vitro studies, including MTT, western blot analysis and cell apoptosis, were utilized to examined biological functions of SHP-1.

Results

Oral administration of SHP-1 agonist showed the potent anti-tumor effects compared to a selective Bruton’s tyrosine kinase (BTK) inhibitor ibrutinib in mice bearing U2932 xenografts. SHP-1 agonist increased SHP-1 activity as well as downregulated p-Lyn in vivo. Here, we demonstrated that immunohistochemical staining for SHP-1 expression was positive in 76% of DLBCL samples. SHP-1 agonist exerted anti-proliferative and apoptotic effects compared with ibrutinib in DLBCL cells. Mechanistically, SHP-1 agonist decreased BCR signaling, especially p-Lyn, and led to apoptosis.

Conclusions

These data suggest that SHP-1 negatively regulates phosphorylation of Lyn, and targeting SHP-1/p-Lyn using SHP-1 agonist has therapeutic potential for treatment of DLBCL.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-022-00518-0.

Development and Characterization of 3D Hybrid Spheroids for the Investigation of the Crosstalk Between B-Cell Non-Hodgkin Lymphomas and Mesenchymal Stromal Cells

Purpose

B-cell non-Hodgkin lymphomas (B-NHLs) are the most common lymphoproliferative malignancy. Despite targeted therapies, the bone marrow involvement remains a challenge in treating aggressive B-NHLs, partly due to the protective interactions of lymphoma cells with mesenchymal stromal cells (MSCs). However, data elucidating the relationship between MSCs and B-NHLs are limited and inconclusive due to the lack of reproducible in vitro three-dimensional (3D) models. Here, we developed and described a size-controlled and stable 3D hybrid spheroids of Ri-1 (diffuse large B-cell lymphoma, DLBCL) and RAJI (Burkitt lymphoma, BL) cells with HS-5 fibroblasts to facilitate research on the crosstalk between B-NHL cells and MSCs.

Materials and Methods

We applied the commercially available agarose hydrogel microwells for a fast, low-cost, and reproducible hybrid lymphoma/stromal spheroids formation. Standard histological automated procedures were used for formalin fixation and paraffin embedding (FFPE) of 3D models to produce good quality slides for histopathology and immunohistochemical staining. Next, we tested the effect of the anti-cancer drugs: doxorubicin (DOX) and ibrutinib (IBR) on mono-cultured and co-cultured B-NHLs with the use of alamarBlue and live/dead cell fluorescence based assays to confirm their relevancy for drug testing studies.

Results

We optimized the conditions for B-NHLs spheroid formation in both: a cell line-specific and application-specific manner. Lymphoma cells aggregate into stable spheroids when co-cultured with stromal cells, of which internal architecture was driven by self-organization. Furthermore, we revealed that co-culturing of lymphoma cells with stromal cells significantly reduced IBR-induced apoptosis compared to the 3D mono-culture.

Conclusion

This article provides details for generating 3D B-NHL spheroids for the studies on the lymphoma- stromal cells. This approach makes it suitable to assess in a relevant in vitro model the activity of new therapeutic agents in B-NHLs.

The New Treatment Methods for Non-Hodgkin Lymphoma in Pediatric Patients

One of the most common cancer malignancies is non-Hodgkin lymphoma, whose incidence is nearly 3% of all 36 cancers combined. It is the fourth highest cancer occurrence in children and accounts for 7% of cancers in patients under 20 years of age. Today, the survivability of individuals diagnosed with non-Hodgkin lymphoma varies by about 70%. Chemotherapy, radiation, stem cell transplantation, and immunotherapy have been the main methods of treatment, which have improved outcomes for many oncological patients. However, there is still the need for creation of novel medications for those who are treatment resistant. Additionally, more effective drugs are necessary. This review gathers the latest findings on non-Hodgkin lymphoma treatment options for pediatric patients. Attention will be focused on the most prominent therapies such as monoclonal antibodies, antibody–drug conjugates, chimeric antigen receptor T cell therapy and others.

Translating the Biology of Diffuse Large B-cell Lymphoma Into Treatment

Diffuse large B-cell lymphoma (DLBCL) is characterized by clinical and molecular heterogeneity; however, this heterogeneity is rarely taken into account by standard-of-care treatment approaches. While the disease was traditionally classified based on transcriptome signatures purporting the tumor cell of origin, recent classification systems have further differentiated these subtypes into clusters based on molecular and genetic features. Alongside a better understanding of the biology of the disease and the signaling pathways involved, emerging therapeutic agents may be better aimed at attacking distinct disease subsets. It is hoped that molecular subtyping at diagnosis will allow patients to be allocated to the appropriate treatment that targets their specific disease subtype, thus advancing the promise of precision medicine in lymphoma, an approach that is most needed. For high-risk disease subsets, this is particularly important, and much research is still needed to develop agents effective in this population. Here, we review recent advances in DLBCL biology and how they can be translated into clinical care.

Metronomic chemotherapy regimens and targeted therapies in non-Hodgkin lymphoma: The best of two worlds

Novel drugs are rapidly moving forward the treatment-paradigm of non-Hodgkin-lymphomas (NHLs). Notwithstanding, especially in aggressive subtypes, chemotherapy remains the pillar of treatment. Indeed, the combination of highly effective Maximum-Tolerated-Dose Chemotherapy (MTD-CHEMO) + "novel drugs", has so far, fallen short from expectations, often because it caused excessive toxicity. Metronomic chemotherapy (mCHEMO), which is the frequent, long-term administration of low dose cytotoxic drugs, may allow more effective and tolerable combinations. mCHEMO pharmacodynamics, has been described as pleiotropic. In fact, it may have different cellular and molecular targets, when drugs or their schedules are modified. Although mCHEMO has been little explored in NHLs, pre-clinical studies - in lymphoma models - which addressed the activity of mCHEMO in combination with novel drugs, have shown very promising results. These included inhibitors of histone deacetylase, mTOR and PI3K/mTOR, as well as the immune checkpoint inhibitor anti-PD-L1. Moreover, a few impressive reports have recently shown all-oral mCHEMO schedules, with or without rituximab, can effectively shrink both B and T-cell aggressive NHLs. Indeed, these regimens allowed elderly-frail patients to achieve sustained remission, while toxicity proved manageable. In our opinion, all-oral mCHEMO, is an active, easy-to start, well-tolerated, and inexpensive therapeutic approach, which deserves further investigation. Most importantly, mCHEMO, holds promise to empower the activity of novel targeted therapies, without causing excessive toxicity.

Prevalence of Healed Plaque and Factors Influencing Its Characteristics Under Optical Coherence Tomography in Patients With Coronary Artery Disease: A Systematic Review, Meta-Analysis, and Meta-Regression

Aim: The purpose of this study was to determine the prevalence of healed plaque and its characteristics under optical coherence tomography (OCT) through a formal systematic review, meta-analysis, and meta-regression. Methods and Results: Thirteen studies were selected from MEDLINE, EMBASE, Cochrane, and online databases. The overall incidence of healed plaques was 40% (95% CI: 39-42), with 37% (95% CI: 35-39) in patients with acute coronary syndrome (ACS) and with 46% (95% CI: 43-49) in patients with stable angina pectoris (SAP). The incidence of healed plaque among culprit plaques (48%, 95% CI: 46-50) was nearly two times higher than that among non-culprit plaques (24%, 95% CI: 21-27). The incidence of thin cap fibroatheroma (TCFA), plaque rupture, microvessel, macrophage accumulation, and calcification was significantly higher in the healed plaque group. Meta-regression revealed an association between smoking (P = 0.033) and healed plaque rupture. Gender (P = 0.047) was independently associated with macrophage accumulation, and mean low-density lipoprotein cholesterol (LDL-C) was independently associated with microvessel. Conclusions: In summary, with a total incidence of 40%, the incidence of healed plaques under OCT was higher in SAP than in ACS, and higher in culprit plaques than in non-culprit plaques. Higher incidence of TCFA, plaque rupture, microvessel, macrophage accumulation, and calcification was found in the healed-plaque group. Smoking, gender, and mean LDL-C level were associated with healed-plaque characteristics.

Targeting of HSP70/HSF1 Axis Abrogates In Vitro Ibrutinib-Resistance in Chronic Lymphocytic Leukemia

Simple Summary

The use of ibrutinib has changed the management and clinical history of patients with multiple-treated chronic lymphocytic leukemia (CLL). Nevertheless, an increasing number of patients develop resistance to treatment, with mechanisms still to be fully clarified. Since HSP70 plays a pivotal role in mediating the survival and the progression of CLL, we herein addressed the role of HSP70 and its regulator HSF1 in the development of ibrutinib-mediated resistance. We found an increase in both proteins when the treatment was failing, and thus the disease was progressing. This suggests the involvement of HSP70 in mechanisms of drug resistance. Moreover, we demonstrated that the use, at different levels, of HSP70/HSF1 axis inhibitors could represent a novel rational therapeutic approach to overcome ibrutinib resistance in those patients who relapsed after this type of treatment.

Abstract

The Btk inhibitor ibrutinib has significantly changed the management of chronic lymphocytic leukemia (CLL) patients. Despite its clinical efficacy, relapses occur, and outcomes after ibrutinib failure are poor. Although BTK and PLCγ2 mutations have been found to be associated with ibrutinib resistance in a fair percentage of CLL patients, no information on resistance mechanisms is available in patients lacking these mutations. The heat shock protein of 70 kDa (HSP70) and its transcription factor heat shock factor 1 (HSF1) play a role in mediating the survival and progression of CLL, as well as taking part in drug resistance in various cancers. We demonstrated that resveratrol and related phenols were able to induce apoptosis in vitro in leukemic cells from CLL untreated patients by acting on the HSP70/HSF1 axis. The same was achieved in cells recovered from 13 CLL patients failing in vivo ibrutinib treatment. HSP70 and HSF1 levels decreased following in vitro treatment, correlating to apoptosis induction. We suggest an involvement of HSP70/HSF1 axis in controlling resistance to ibrutinib in CLL cells, since their inhibition is effective in inducing in vitro apoptosis in cells from ibrutinib refractory patients. The targeting of HSP70/HSF1 axis could represent a novel rational therapeutic strategy for CLL, also for relapsing patients.

Characteristics and treatment patterns of relapsed/refractory diffuse large B-cell lymphoma in patients receiving ≥3 therapy lines in post-CAR-T era

OBJECTIVE

Several novel treatments have been approved for relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL) since chimeric antigen receptor T-cell (CAR-T) therapy became available. The objective of this study was to describe characteristics and treatment patterns in patients with R/R DLBCL post-CAR-T approval.

METHODS

Adult patients with R/R DLBCL who initiated third-line treatment or later (3 L+) since 18 October 2017 were identified using administrative claims from IQVIA PharMetrics Plus (1 January 2014-31 March 2020). Treatments were categorized as chemotherapy/chemoimmunotherapy (CT/CIT), targeted therapies, CAR-T and stem cell transplant (SCT). Treatment distribution, treatment duration of CT/CIT and targeted therapies, and initiation of next-line therapy were described for patients receiving 3 L; analyses were repeated for 4 L.

RESULTS

A total of 145 patients received 3 L between 18 October 2017 and 31 March 2020. Mean age was 57 years, and 34% were female. CT/CIT (44.9%), targeted therapies (26.9%), CAR-T (17.2%) and SCT (11.0%) were administered in 3 L. The median treatment duration was 2.9 months for CT/CIT and targeted therapies combined. 31% of patients initiated 4 L within a median follow-up of 5.8 months. Among patients who received 4 L (N = 55), targeted therapies were most commonly used (36.4%), and the median treatment duration was 2.5 months.

CONCLUSIONS

Post-CAR-T approval, the majority of patients were treated with CT/CIT or targeted therapies in 3 L and 4 L, though most of the targeted therapies prescribed are not indicated for DLBCL. Treatment duration was short. A high proportion of patients moved to the next line of therapy (LOT) during a short follow-up period. This study highlights the unmet need for more effective treatments for patients with R/R DLBCL in 3 L+.

Efficacy and Safety of Ibrutinib in Central Nervous System Lymphoma: A PRISMA-Compliant Single-Arm Meta-Analysis

Background

Central nervous system lymphoma (CNSL) is an aggressive lymphoma. Studies investigating primary CNSL determined that the Bruton tyrosine kinase (BTK) played an important role in pathogenesis. Ibrutinib, an oral BTK inhibitor, is a new treatment strategy for CNSL. The purpose of this meta-analysis was to clarify the effectiveness and safety of ibrutinib in the treatment of CNSL.

Methods

A systematic search of PubMed, Embase, Cochrane library, Wanfang Data Knowledge Service Platform, and China National Knowledge Infrastructure databases was conducted through to 31 October 2019. Studies involving patients with CNSL who received ibrutinib that reported the overall response (OR), complete remission (CR), and partial response (PR) were included. The random-effects or fixed-effects model with double arcsine transformation was used for the pooled rates and 95% confidence intervals (CI) were determined for all outcomes.

Results

Eight studies including 162 patients were identified and included in the meta-analysis. The pooled OR rate after treatment with ibrutinib was 69% (95% CI, 61-79%, I² = 47.57%, p = 0.06), while the pooled CR and PR was 52% (95% CI, 35-68%, I² = 74.95%, p = 0.00) and 17% (95% CI, 7-30%, I² = 67.85%, p = 0.00), respectively. Among PCNSL patients, including new diagnoses PCNSL and R/R PCNSL, the pooled OR rate was 72% (95% CI, 63-80%, I² = 49.20%, p = 0.06) while the pooled CR and PR rates were 53% (95% CI, 33-73%, I² = 75.04%, p = 0.00) and 22% (95% CI, 14-30%, I² = 46.30%, p = 0.07), respectively. Common adverse events above grade 3 included cytopenia and infections.

Conclusions

The ibrutinib-containing therapy was well tolerated and offered incremental benefit to patients with CNSL. However, randomized-controlled studies that directly compare efficacy and adverse events of ibrutinib are still needed.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42020218974.

Ibrutinib in Patients with Relapsed or Refractory Diffuse Large B-Cell Lymphoma: A Retrospective Study

Limited treatment options are available for relapsed or refractory diffuse large B cell lymphoma (RR DLBCL). Few clinical studies have reported the use of Ibrutinib, a covalent Bruton Tyrosine kinase (BTK) inhibitor, in RR DLBCL. There are relatively few clinical studies about Ibrutinib in RR DLBCL now. We retrospectively investigated the safety and efficacy of Ibrutinib (alone or in combination with other drugs) in patients with RR DLBCL. We reviewed the medical records of 40 RR DLBCL patients who received Ibrutinib alone or in combination with other drugs in our hospital from June 2018 to August 2020. The objective response rate (ORR) of RR DLBCL patients on Ibrutinib was 22.5%. The median progression free survival time (PFS) was 13.0 months (95% CI 8.914–17.086), and the median overall survival time (OS) was 15.0 months (95% CI 11.931–18.089). Rash (25.0%) and fatigue (25.0%) were the most common adverse reactions in this study. The application of Ibrutinib to patients with RR DLBCL has good short-term efficacy, and the adverse reactions are well tolerated. Combined treatment of Ibrutinib with other drugs has been found to more effective than Ibrutinib therapy alone.

Real-life experience with the combination of polatuzumab vedotin, rituximab, and bendamustine in aggressive B-cell lymphomas

Transplant-ineligible relapsed/refractory (rr) diffuse large B-cell lymphoma (DLBCL) patients represent an unmet medical need. Polatuzumab vedotin (Pola), an anti-CD79b antibody-drug-conjugate (ADG), with bendamustine- rituximab(BR) has recently gained approval for these patients, both in the USA and Europe, based on the GO29365 phase IIb trial. Real-life data with Pola are extremely limited. We report the outcomes of 61 Greek patients, who received Pola-(B)R mainly within a compassionate use program. Treatment was given for up to six 21-day cycles. Bendamustine was omitted in three cases due to previous short-lived responses. Fourty-nine rrDLBCL(efficacy cohort-EC) and 58 rr aggressive B-NHL (safety cohort-SC) patients received at least 1 Pola-BR cycle. Twenty-one (43%) patients of the EC responded with 12/49 (25%) CR and 9/49 (18%) PR as best response. Median progression-free survival, overall survival and duration of response were 4.0, 8.5, and 8.5 months respectively, while 55% of patients experienced a grade ≥3 adverse event, mainly hematologic. Treatment discontinuations and death during treatment were mainly due to disease progression. Twenty-two (41%) patients received further treatment; 11/22 are still alive, including one after CAR-T cells, and two after stem cell transplantation. Our data confirm that Pola-BR is a promising treatment for rrDLBCL patients, inducing an adequate response rate with acceptable toxicity. Pola-BR could be used as bridging therapy before further consolidative treatments.

TNF receptor-associated factor 3 restrains B-cell receptor signaling in normal and malignant B cells

TRAF3 has diverse signaling functions, which vary by cell type. Uniquely in B lymphocytes, TRAF3 inhibits homeostatic survival. Highlighting the role of TRAF3 as a tumor suppressor, loss-of-function TRAF3 mutations are associated with human B-cell malignancies, while B-cell-specific deletion of TRAF3 in mice leads to autoimmunity and lymphoma development. The role of TRAF3 in inhibiting noncanonical NF-κB activation, CD40 and BAFF-R signaling to B cells is well documented. In contrast, TRAF3 enhances many T-cell effector functions, through associating with and enhancing signaling by the T-cell receptor (TCR)-CD28 complex. The present study was designed to determine the role of TRAF3 in signaling via the B-cell antigen receptor (BCR). The BCR is crucial for antigen recognition, survival, proliferation, and antibody production, and defects in BCR signaling can promote abnormal survival of malignant B cells. Here, we show that TRAF3 is associated with both CD79B and the BCR-activated kinases Syk and Btk following BCR stimulation. BCR-induced phosphorylation of Syk and additional downstream kinases was increased in TRAF3^−/− B cells, with regulation observed in both follicular and marginal zone B-cell subsets. BCR stimulation of TRAF3^−/− B cells resulted in increased surface expression of MHC-II, CD80, and CD86 molecules. Interestingly, increased survival of TRAF3^−/− primary B cells was resistant to inhibition of Btk, while TRAF3-deficient malignant B-cell lines showed enhanced sensitivity. TRAF3 serves to restrain normal and malignant BCR signaling, with important implications for its role in normal B-cell biology and abnormal survival of malignant B cells.

Feline lymphoplasmacytic rhinitis (FLPCR): Severity of inflammation correlates with reduced mucosal IgA expression

Feline lymphoplasmacytic rhinitis (FLPCR) is a rare disease with an unclear pathogenesis characterized by lymphoplasmacytic (LPC) inflammation and progressive tissue destruction. Aims were to evaluate specific FLPCR clinical and pathological features to gain insights into disease pathogenesis. Signalment, clinical signs, serology and 47 pin. h biopsies were retrospectively collected from 33 FLPCR and 3 normal cats. Microscopical lesions and immunohistochemistry results utilizing anti-CD3, anti-CD20, anti-FOXP3, anti-feline-IgA, IgG, IgE and anti-FeLV (p27 and gp70), FIV, FCV and, FHV were scored and most were analyzed statistically. The majority of cats were domestic short haired (26/31) with median age of 11 years and a 0.35 F/M ratio. Serology evidenced 3/22 FIV and 1/22 FeLV positive cats. Immunohistochemistry evidenced 1/33 FeLV-p27 positive cats. Common clinical signs were sneezing (19/24 [79 %]), mucous discharge (13/24 [54 %]) and stertor (10/24 [42 %]). In normal tissues, IgAs were expressed in mucin, apical and lateral cell membrane of columnar cells and in periglandular plasma cells. IgGs were expressed in 20-30 % of columnar cells. Number of clinical signs was statistically significantly higher in female cats (p < 0.0001) and was significantly correlated with chronicity (p = 0.004), and IgG scores (p = 0.01). LPC severity scores correlated positively with infiltration of neutrophils (p = 0.015), gland destruction (p = 0.019) and angiogenesis (p = 0.016) and negatively with fibrosis (p < 0.0001). LPC severity scores were also significantly associated to female sex (p = 0.01) and to IgA (p = 0.03), with higher IgA scores associated to lower LPC scores. FLPCR associated to disruption of mucosal defense mechanisms generating cycles of tissue inflammation, tissue damage and repair with progressive loss of function independent from viral infections.