Patterns and timing of perioperative blood transfusion and association with outcomes after radical cystectomy.

BACKGROUND: Perioperative blood transfusion (PBT) has been associated with worse outcomes across tumor types, including bladder cancer. We report our institutional experience with PBT utilization in the setting of radical cystectomy (RC) for patients with bladder cancer, exploring whether timing of PBT receipt influences perioperative and oncologic outcomes. METHODS: Consecutive patients with bladder cancer treated with RC were identified. PBT was defined as red blood cell transfusion during RC or the postoperative admission. Clinicopathologic and peri and/or postoperative parameters were extracted and compared between patients who did and did not receive PBT using Mann Whitney U Test, chi-square, and log-rank test. Overall (OS) and recurrence-free survival (RFS) were estimated with the Kaplan Meier method. Univariate/multivariate logistic and Cox proportional hazards regression were used to identify variables associated with postoperative and oncologic outcomes, respectively. RESULTS: The cohort consisted of 747 patients (77% men; median age 67 years). Median follow-up was 61.5 months (95% CI 55.8-67.2) At least one postoperative complication (90-day morbidity) occurred in 394 (53%) patients. Median OS and RFS were 91.8 months (95% CI: 76.0-107.6) and 66.0 months (95% CI: 48.3-83.7), respectively. On multivariate analysis, intraoperative, but not postoperative, BT was independently associated with shorter OS (HR: 1.74, 95% CI: 1.32-2.29) and RFS (HR: 1.55, 95%CI: 1.20-2.01), after adjusting for relevant clinicopathologic variables. PBT (intra- or post- operative) was significantly associated with prolonged postoperative hospitalization ≥10 days. CONCLUSIONS: Intraoperative BT was associated with inferior OS and RFS, and PBT overall was associated with prolonged hospitalization following RC. Further studies are needed to validate this finding and explore potential causes for this observation.

A New Prognostic Model in Patients with Advanced Urothelial Carcinoma Treated with First-line Immune Checkpoint Inhibitors.

BACKGROUND: While immune checkpoint inhibitors (ICIs) are approved in the first-line (1L) setting for cisplatin-unfit patients with programmed death-ligand 1 (PD-L1)-high tumors or for platinum (cisplatin/carboplatin)-unfit patients, response rates remain modest and outcomes vary with no clinically useful biomarkers (except for PD-L1). OBJECTIVE: We aimed to develop a prognostic model for overall survival (OS) in patients receiving 1L ICIs for advanced urothelial cancer (aUC) in a multicenter cohort study. DESIGN, SETTING, AND PARTICIPANTS: Patients treated with 1L ICIs for aUC across 24 institutions and five countries (in the USA and Europe) outside clinical trials were included in this study. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: We used a stepwise, hypothesis-driven approach using clinician-selected covariates to develop a new risk score for patients receiving ICIs in the 1L setting. Demographics, clinicopathologic data, treatment patterns, and OS were collected uniformly. Univariate Cox regression was performed on 18 covariates hypothesized to be associated with OS based on published data. Variables were retained for multivariate analysis (MVA) if they correlated with OS (p < 0.2) and were included in the final model if p < 0.05 on MVA. Retained covariates were assigned points based on the beta coefficient to create a risk score. Stratified median OS and C-statistic were calculated. RESULTS AND LIMITATIONS: Among 984 patients, 357 with a mean age of 71 yr were included in the analysis, 27% were female, 68% had pure UC, and 13% had upper tract UC. Eastern Cooperative Oncology Group performance status ≥2, albumin <3.5 g/dl, neutrophil:lymphocyte ratio >5, and liver metastases were significant prognostic factors on MVA and were included in the risk score. C index for new 1L risk score was 0.68 (95% confidence interval 0.65-0.71). Limitations include retrospective nature and lack of external validation. CONCLUSIONS: We developed a new 1L ICI risk score for OS based on data from patients with aUC treated with ICIs in the USA and Europe outside of clinical trials. The score components highlight readily available factors related to tumor biology and treatment response. External validation is being pursued. PATIENT SUMMARY: With multiple new treatments under development and approved for advanced urothelial carcinoma, it can be difficult to identify the best treatment sequence for each patient. The risk score may help inform treatment discussions and estimate outcomes in patients treated with first-line immune checkpoint inhibitors, while it can also impact clinical trial design and endpoints. TAKE HOME MESSAGE: A new risk score was developed for advanced urothelial carcinoma treated with first-line immune checkpoint inhibitors. The score assigned Eastern Cooperative Oncology Group performance status ≥2, albumin <3.5 g/dl, neutrophil:lymphocyte ratio >5, and liver metastases each one point, with a higher score being associated with worse overall survival.

Histological Subtypes and Response to PD-1/PD-L1 Blockade in Advanced Urothelial Cancer: A Retrospective Study.

PURPOSE: Urinary tract cancer can be pure urothelial carcinoma, pure nonurothelial carcinoma or variant urothelial carcinoma (defined here as mixed urothelial carcinoma). Little is known regarding outcomes for patients with variant urothelial carcinoma receiving immune checkpoint inhibitors. We hypothesized that variant urothelial carcinoma does not compromise immune checkpoint inhibitor efficacy in patients with advanced urothelial carcinoma. MATERIALS AND METHODS: We performed a retrospective cohort study across 18 institutions. Demographic, clinicopathological, treatment and outcomes data were collected for patients with advanced urothelial carcinoma who received immune checkpoint inhibitors. Patients were divided into pure vs variant urothelial carcinoma subgroups, with variant urothelial carcinoma further divided by type of variant (ie squamous, neuroendocrine etc). We compared overall response rate using univariate and multivariate logistic regression and progression-free survival and overall survival using Kaplan-Meier and univariate and multivariate Cox proportional hazards. RESULTS: Overall 519 patients were identified, with 395, 406 and 403 included in overall response rate, overall survival and progression-free survival analyses, respectively. Overall response rate to immune checkpoint inhibitors between patients with pure vs variant urothelial carcinoma was comparable (28% vs 29%, p=0.90) without significant differences for individual subtypes vs pure urothelial carcinoma. Median overall survival for patients with pure urothelial carcinoma was 11.0 months vs 10.1 months for variant urothelial carcinoma (p=0.60), but only 4.6 months for patients with neuroendocrine features (9 patients, HR 2.75, 95% CI 1.40-5.40 vs pure urothelial carcinoma, p=0.003). Median progression-free survival was 4.1 months for pure vs 5.2 months for variant urothelial carcinoma (p=0.43) and 3.7 months for neuroendocrine features (HR 1.87, 95% CI 0.92-3.79 vs pure urothelial carcinoma, p=0.09). CONCLUSIONS: Overall response rate to immune checkpoint inhibitors was comparable across histological types. However, overall survival was worse for patients with tumors containing neuroendocrine features. Variant urothelial carcinoma should not exclude patients from receiving immune checkpoint inhibitors.

Intratumoral Delivery of Plasmid IL12 Via Electroporation Leads to Regression of Injected and Noninjected Tumors in Merkel Cell Carcinoma.

PURPOSE: IL12 promotes adaptive type I immunity and has demonstrated antitumor efficacy, but systemic administration leads to severe adverse events (AE), including death. This pilot trial investigated safety, efficacy, and immunologic activity of intratumoral delivery of IL12 plasmid DNA (tavo) via in vivo electroporation (i.t.-tavo-EP) in patients with Merkel cell carcinoma (MCC), an aggressive virus-associated skin cancer. PATIENTS AND METHODS: Fifteen patients with MCC with superficial injectable tumor(s) received i.t.-tavo-EP on days 1, 5, and 8 of each cycle. Patients with locoregional MCC (cohort A, N = 3) received one cycle before definitive surgery in week 4. Patients with metastatic MCC (cohort B, N = 12) received up to four cycles total, administered at least 6 weeks apart. Serial tumor and blood samples were collected. RESULTS: All patients successfully completed at least one cycle with transient, mild (grades 1 and 2) AEs and without significant systemic toxicity. Sustained (day 22) intratumoral expression of IL12 protein was observed along with local inflammation and increased tumor-specific CD8+ T-cell infiltration, which led to systemic immunologic and clinical responses. The overall response rate was 25% (3/12) in cohort B, with 2 patients experiencing durable clinical benefit (16 and 55+ months, respectively). Two cohort A patients (1 with pathologic complete remission) were recurrence-free at 44+ and 75+ months, respectively. CONCLUSIONS: I.t.-tavo-EP was safe and feasible without systemic toxicity. Sustained local expression of IL12 protein and local inflammation led to systemic immune responses and clinically meaningful benefit in some patients. Gene electrotransfer, specifically i.t.-tavo-EP, warrants further investigation for immunotherapy of cancer.

Intratumoral G100, a TLR4 Agonist, Induces Antitumor Immune Responses and Tumor Regression in Patients with Merkel Cell Carcinoma.

PURPOSE: G100 is a toll-like receptor 4 (TLR4) agonist that triggers innate and adaptive antitumor immune responses in preclinical models. This pilot study assessed the safety, efficacy, and immunologic activity of intratumoral (IT) administration of G100 in patients with Merkel cell carcinoma (MCC). PATIENTS AND METHODS: Patients with locoregional MCC (n = 3; cohort A) received neoadjuvant IT G100 (2 weekly doses at 5 µg/dose) followed by surgery and radiotherapy; patients with metastatic MCC (n = 7; cohort B) received 3 doses in a 6-week cycle and could receive additional cycles with/without radiotherapy. RESULTS: IT G100 was safe and feasible in both neoadjuvant and metastatic settings. Treatment-related adverse events were mostly grade 1 or 2 injection-site reactions. IT G100 led to increased inflammation in the injected tumors with infiltration of CD8+ and CD4+ T cells and activation of immune-related genes. These proinflammatory changes were associated with local tumor regression and appeared to promote systemic immunity. All 3 cohort A patients successfully completed therapy; 2 patients remain recurrence free at 44+ and 41+ months, including 1 with a pathologic complete response after G100 alone. In cohort B, 2 patients achieved sustained partial responses, both lasting 33+ months after 2 cycles of therapy. CONCLUSIONS: In this first-in-human study, IT G100 induced antitumor immune responses, demonstrated acceptable safety, and showed encouraging clinical activity.See related commentary by Marquez-Rodas et al., p. 1127.

Merkel cell polyomavirus-specific immune responses in patients with Merkel cell carcinoma receiving anti-PD-1 therapy.

BACKGROUND: Merkel cell carcinoma (MCC) is an aggressive skin cancer that frequently responds to anti-PD-1 therapy. MCC is associated with sun exposure and, in 80% of cases, Merkel cell polyomavirus (MCPyV). MCPyV-specific T and B cell responses provide a unique opportunity to study cancer-specific immunity throughout PD-1 blockade therapy. METHODS: Immune responses were assessed in patients (n = 26) with advanced MCC receiving pembrolizumab. Peripheral blood mononuclear cells (PBMC) were collected at baseline and throughout treatment. MCPyV-oncoprotein antibodies were quantified and T cells were assessed for MCPyV-specificity via tetramer staining and/or cytokine secretion. Pre-treatment tumor biopsies were analyzed for T cell receptor clonality. RESULTS: MCPyV oncoprotein antibodies were detectable in 15 of 17 (88%) of virus-positive MCC (VP-MCC) patients. Antibodies decreased in 10 of 11 (91%) patients with responding tumors. Virus-specific T cells decreased over time in patients who had a complete response, and increased in patients who had persistent disease. Tumors that were MCPyV(+) had a strikingly more clonal (less diverse) intratumoral TCR repertoire than virus-negative tumors (p = 0.0001). CONCLUSIONS: Cancer-specific T and B cell responses generally track with disease burden during PD-1 blockade, in proportion to presence of antigen. Intratumoral TCR clonality was significantly greater in VP-MCC than VN-MCC tumors, suggesting expansion of a limited number of dominant clones in response to fewer immunogenic MCPyV antigens. In contrast, VN-MCC tumors had lower clonality, suggesting a diverse T cell response to numerous neoantigens. These findings reveal differences in tumor-specific immunity for VP-MCC and VN-MCC, both of which often respond to anti-PD-1 therapy.

Multidimensional, quantitative assessment of PD-1/PD-L1 expression in patients with Merkel cell carcinoma and association with response to pembrolizumab.

BACKGROUND: We recently reported a 56% objective response rate in patients with advanced Merkel cell carcinoma (MCC) receiving pembrolizumab. However, a biomarker predicting clinical response was not identified. METHODS: Pretreatment FFPE tumor specimens (n = 26) were stained for CD8, PD-L1, and PD-1 by immunohistochemistry/immunofluorescence (IHC/IF), and the density and distribution of positive cells was quantified to determine the associations with anti-PD-1 response. Multiplex IF was used to test a separate cohort of MCC archival specimens (n = 16), to identify cell types expressing PD-1. RESULTS: Tumors from patients who responded to anti-PD-1 showed higher densities of PD-1+ and PD-L1+ cells when compared to non-responders (median cells/mm2, 70.7 vs. 6.7, p = 0.03; and 855.4 vs. 245.0, p = 0.02, respectively). There was no significant association of CD8+ cell density with clinical response. Quantification of PD-1+ cells located within 20 µm of a PD-L1+ cell showed that PD-1/PD-L1 proximity was associated with clinical response (p = 0.03), but CD8/PD-L1 proximity was not. CD4+ and CD8+ cells in the TME expressed similar amounts of PD-1. CONCLUSIONS: While the binomial presence or absence of PD-L1 expression in the TME was not sufficient to predict response to anti-PD-1 in patients with MCC, we show that quantitative assessments of PD-1+ and PD-L1+ cell densities as well as the geographic interactions between these two cell populations correlate with clinical response. Cell types expressing PD-1 in the TME include CD8+ T-cells, CD4+ T-cells, Tregs, and CD20+ B-cells, supporting the notion that multiple cell types may potentiate tumor regression following PD-1 blockade.

Tumor-Infiltrating Merkel Cell Polyomavirus-Specific T Cells Are Diverse and Associated with Improved Patient Survival.

Tumor-infiltrating CD8+ T cells are associated with improved survival of patients with Merkel cell carcinoma (MCC), an aggressive skin cancer causally linked to Merkel cell polyomavirus (MCPyV). However, CD8+ T-cell infiltration is robust in only 4% to 18% of MCC tumors. We characterized the T-cell receptor (TCR) repertoire restricted to one prominent epitope of MCPyV (KLLEIAPNC, "KLL") and assessed whether TCR diversity, tumor infiltration, or T-cell avidity correlated with clinical outcome. HLA-A*02:01/KLL tetramer+ CD8+ T cells from MCC patient peripheral blood mononuclear cells (PBMC) and tumor-infiltrating lymphocytes (TIL) were isolated via flow cytometry. TCRß (TRB) sequencing was performed on tetramer+ cells from PBMCs or TILs (n = 14) and matched tumors (n = 12). Functional avidity of T-cell clones was determined by IFNγ production. We identified KLL tetramer+ T cells in 14% of PBMC and 21% of TIL from MCC patients. TRB repertoires were strikingly diverse (397 unique TRBs were identified from 12 patients) and mostly private (only one TCRb clonotype shared between two patients). An increased fraction of KLL-specific TIL (>1.9%) was associated with significantly increased MCC-specific survival P = 0.0009). T-cell cloning from four patients identified 42 distinct KLL-specific TCRa/b pairs. T-cell clones from patients with improved MCC-specific outcomes were more avid (P < 0.05) and recognized an HLA-appropriate MCC cell line. T cells specific for a single MCPyV epitope display marked TCR diversity within and between patients. Intratumoral infiltration by MCPyV-specific T cells was associated with significantly improved MCC-specific survival, suggesting that augmenting the number or avidity of virus-specific T cells may have therapeutic benefit. Cancer Immunol Res; 5(2); 137-47. ©2017 AACR.

PD-1 Blockade with Pembrolizumab in Advanced Merkel-Cell Carcinoma.

BACKGROUND: Merkel-cell carcinoma is an aggressive skin cancer that is linked to exposure to ultraviolet light and the Merkel-cell polyomavirus (MCPyV). Advanced Merkel-cell carcinoma often responds to chemotherapy, but responses are transient. Blocking the programmed death 1 (PD-1) immune inhibitory pathway is of interest, because these tumors often express PD-L1, and MCPyV-specific T cells express PD-1. METHODS: In this multicenter, phase 2, noncontrolled study, we assigned adults with advanced Merkel-cell carcinoma who had received no previous systemic therapy to receive pembrolizumab (anti-PD-1) at a dose of 2 mg per kilogram of body weight every 3 weeks. The primary end point was the objective response rate according to Response Evaluation Criteria in Solid Tumors, version 1.1. Efficacy was correlated with tumor viral status, as assessed by serologic and immunohistochemical testing. RESULTS: A total of 26 patients received at least one dose of pembrolizumab. The objective response rate among the 25 patients with at least one evaluation during treatment was 56% (95% confidence interval [CI], 35 to 76); 4 patients had a complete response, and 10 had a partial response. With a median follow-up of 33 weeks (range, 7 to 53), relapses occurred in 2 of the 14 patients who had had a response (14%). The response duration ranged from at least 2.2 months to at least 9.7 months. The rate of progression-free survival at 6 months was 67% (95% CI, 49 to 86). A total of 17 of the 26 patients (65%) had virus-positive tumors. The response rate was 62% among patients with MCPyV-positive tumors (10 of 16 patients) and 44% among those with virus-negative tumors (4 of 9 patients). Drug-related grade 3 or 4 adverse events occurred in 15% of the patients. CONCLUSIONS: In this study, first-line therapy with pembrolizumab in patients with advanced Merkel-cell carcinoma was associated with an objective response rate of 56%. Responses were observed in patients with virus-positive tumors and those with virus-negative tumors. (Funded by the National Cancer Institute and Merck; ClinicalTrials.gov number, NCT02267603.).

Single-fraction radiation therapy in patients with metastatic Merkel cell carcinoma.

Merkel cell carcinoma (MCC) is an aggressive, polyomavirus-associated cancer with limited therapeutic options for metastatic disease. Cytotoxic chemotherapy is associated with high response rates, but responses are seldom durable and toxicity is considerable. Here, we report our experience with palliative single-fraction radiotherapy (SFRT) in patients with metastatic MCC. We conducted retrospective analyses of safety and efficacy outcomes in patients that received SFRT (8 Gy) to MCC metastases between 2010 and 2013. Twenty-six patients were treated with SFRT to 93 MCC tumors located in diverse sites that included skin, lymph nodes, and visceral organs. Objective responses were observed in 94% of the measurable irradiated tumors (86/92). Complete responses were observed in 45% of tumors (including bulky tumors up to 16 cm). "In field" lesion control was durable with no progression in 77% (69/89) of treated tumors during median follow-up of 277 days among 16 living patients. Clinically significant toxicity was seen in only two patients who had transient side effects. An exploratory analysis suggested a higher rate of in-field progression in patients with an immunosuppressive comorbidity or prior recent chemotherapy versus those without (30% and 9%, respectively; P = 0.03). Use of SFRT in palliating MCC patients was associated with an excellent in field control rate and durable responses at treated sites, and with minimal toxicity. SFRT may represent a convenient and appealing alternative to systemic chemotherapy for palliation, for which most patients with oligometastatic MCC are eligible. SFRT may also synergize with emerging systemic immune stimulants by lowering tumor burden and enhancing presentation of viral/tumor antigens.

Emerging and mechanism-based therapies for recurrent or metastatic Merkel cell carcinoma.

Merkel cell carcinoma (MCC) is a rare but aggressive neuroendocrine skin cancer with a disease-specific mortality of approximately 40 %. The association of MCC with a recently discovered polyomavirus, combined with the increased incidence and mortality of MCC among immunocompromised patients, highlight the importance of the immune system in controlling this cancer. Initial management of MCC is summarized within the NCCN guidelines and in recently published reviews. The high rate of recurrent and metastatic disease progression in MCC, however, presents a major challenge in a cancer that lacks mechanism-based, disease-specific therapies. Traditional treatment approaches have focused on cytotoxic chemotherapy that, despite frequent initial efficacy, rarely provides durable responses and has high morbidity among the elderly. In addition, the immunosuppressive nature of chemotherapy is of concern when treating a virus-associated cancer for which survival is unusually tightly linked to immune function. With a median survival of 9.6 months after development of an initial metastasis (n = 179, described herein), and no FDA-approved agents for this cancer, there is an urgent need for more effective treatments. We review diverse management options for patients with advanced MCC, with a focus on emerging and mechanism-based therapies, some of which specifically target persistently expressed viral antigens. These treatments include single-dose radiation and novel immunotherapies, some of which are in clinical trials. Due to their encouraging efficacy, low toxicity, and lack of immune suppression, these therapies may offer viable alternatives to traditional cytotoxic chemotherapy.

Role for CD21 in the establishment of an extracellular HIV reservoir in lymphoid tissues.

Follicular dendritic cells (FDC) represent a major extracellular reservoir for HIV. A better understanding of the mechanisms of virion attachment to FDC may offer new avenues for reducing viral burdens in infected individuals. We used a murine model to investigate the establishment of extracellular HIV reservoirs in lymph nodes (LN). Consistent with findings in human tissues, CD21 was required for trapping of HIV to LN cells, as evidenced by significantly reduced virion binding when mice were pretreated with a C3 ligand-blocking anti-CD21 mAb and absence of virion trapping in CD21 knockout mice. Also consistent with findings in human tissues, the majority of HIV virions were associated with the FDC-enriched fraction of LN cell preparations. Somewhat surprisingly, HIV-specific Abs were not essential for HIV binding to LN cells, indicating that seeding of the FDC reservoir may begin shortly after infection and before the development of HIV-specific Abs. Finally, the virion-displacing potential for anti-CD21 mAbs was investigated. Treatment of mice with anti-CD21 mAbs several days after injection of HIV significantly reduced HIV bound to LN cells. Our findings demonstrate a critical role for CD21 in HIV trapping by LN cells and suggest a new therapeutic avenue for reducing HIV reservoirs.

Compromised B cell responses to influenza vaccination in HIV-infected individuals.

BACKGROUND: Yearly influenza vaccination, although recommended for human immunodeficiency virus (HIV)-infected individuals, has not received thorough evaluation in the era of antiretroviral therapy. We assessed the impact of HIV disease on B cell responses to influenza vaccination. METHODS: Sixty-four HIV-infected and 17 HIV-negative individuals received the 2003-2004 trivalent inactivated influenza vaccine. Frequencies of influenza-specific antibody-secreting cells (ASCs) were measured by enzyme-linked immunospot (ELISPOT) assay, and antibody responses were measured by hemagglutination-inhibition (HI) assay. Memory responses to influenza were measured by ELISPOT assay after polyclonal activation of B cells in vitro. RESULTS: Prevaccination HI titers were significantly higher in HIV-negative than in HIV-infected individuals. Peak HI titers and influenza-specific ASC frequencies were directly correlated with CD4+ T cell counts in HIV-infected individuals. Influenza-specific memory B cell responses were significantly lower in HIV-infected than in HIV-negative individuals and were directly correlated with CD4+ T cell counts. CONCLUSIONS: HIV infection is associated with a weak antibody response to influenza vaccination that is compounded by a poor memory B cell response. CD4+ T cell count is a critical determinant of responsiveness to influenza vaccination, and the contribution of plasma HIV RNA level is suggestive and warrants further investigation.

Decreased survival of B cells of HIV-viremic patients mediated by altered expression of receptors of the TNF superfamily.

Human immunodeficiency virus (HIV) infection leads to numerous perturbations of B cells through mechanisms that remain elusive. We performed DNA microarray, phenotypic, and functional analyses in an effort to elucidate mechanisms of B cell perturbation associated with ongoing HIV replication. 42 genes were up-regulated in B cells of HIV-viremic patients when compared with HIV-aviremic and HIV-negative patients, the majority of which were interferon (IFN)-stimulated or associated with terminal differentiation. Flow cytometry confirmed these increases and indicated that CD21(low) B cells, enhanced in HIV-viremic patients, were largely responsible for the changes. Increased expression of the tumor necrosis factor (TNF) superfamily (TNFSF) receptor CD95 correlated with increased susceptibility to CD95-mediated apoptosis of CD21(low) B cells, which, in turn, correlated with HIV plasma viremia. Increased expression of BCMA, a weak TNFSF receptor for B lymphocyte stimulator (BLyS), on CD21(low) B cells was associated with a concomitant reduction in the expression of the more potent BLyS receptor, BAFF-R, that resulted in reduced BLyS binding and BLyS-mediated survival. These findings demonstrate that altered expression of genes associated with IFN stimulation and terminal differentiation in B cells of HIV-viremic patients lead to an increased propensity to cell death, which may have substantial deleterious effects on B cell responsiveness to antigenic stimulation.

Decreased survival of B cells of HIV-viremic patients mediated by altered expression of receptors of the TNF superfamily.

Human immunodeficiency virus (HIV) infection leads to numerous perturbations of B cells through mechanisms that remain elusive. We performed DNA microarray, phenotypic, and functional analyses in an effort to elucidate mechanisms of B cell perturbation associated with ongoing HIV replication. 42 genes were up-regulated in B cells of HIV-viremic patients when compared with HIV-aviremic and HIV-negative patients, the majority of which were interferon (IFN)-stimulated or associated with terminal differentiation. Flow cytometry confirmed these increases and indicated that CD21(low) B cells, enhanced in HIV-viremic patients, were largely responsible for the changes. Increased expression of the tumor necrosis factor (TNF) superfamily (TNFSF) receptor CD95 correlated with increased susceptibility to CD95-mediated apoptosis of CD21(low) B cells, which, in turn, correlated with HIV plasma viremia. Increased expression of BCMA, a weak TNFSF receptor for B lymphocyte stimulator (BLyS), on CD21(low) B cells was associated with a concomitant reduction in the expression of the more potent BLyS receptor, BAFF-R, that resulted in reduced BLyS binding and BLyS-mediated survival. These findings demonstrate that altered expression of genes associated with IFN stimulation and terminal differentiation in B cells of HIV-viremic patients lead to an increased propensity to cell death, which may have substantial deleterious effects on B cell responsiveness to antigenic stimulation.