Acute Myeloid Leukemia Causes T Cell Exhaustion and Depletion in a Humanized Graft-versus-Leukemia Model.

Allogeneic hematopoietic stem cell transplantation (alloSCT) is, in many clinical settings, the only curative treatment for acute myeloid leukemia (AML). The clinical benefit of alloSCT greatly relies on the graft-versus-leukemia (GVL) effect. However, AML relapse remains the top cause of posttransplant death; this highlights the urgent need to enhance GVL. Studies of human GVL have been hindered by the lack of optimal clinically relevant models. In this article, we report, the successful establishment of a novel (to our knowledge) humanized GVL model system by transplanting clinically paired donor PBMCs and patient AML into MHC class I/II knockout NSG mice. We observed significantly reduced leukemia growth in humanized mice compared with mice that received AML alone, demonstrating a functional GVL effect. Using this model system, we studied human GVL responses against human AML cells in vivo and discovered that AML induced T cell depletion, likely because of increased T cell apoptosis. In addition, AML caused T cell exhaustion manifested by upregulation of inhibitory receptors, increased expression of exhaustion-related transcription factors, and decreased T cell function. Importantly, combined blockade of human T cell-inhibitory pathways effectively reduced leukemia burden and reinvigorated CD8 T cell function in this model system. These data, generated in a highly clinically relevant humanized GVL model, not only demonstrate AML-induced inhibition of alloreactive T cells but also identify promising therapeutic strategies targeting T cell depletion and exhaustion for overcoming GVL failure and treating AML relapse after alloSCT.

Multi-dimensional analysis identifies an immune signature predicting response to decitabine treatment in elderly patients with AML.

Decitabine is a DNA-hypomethylating agent that has been widely applied for the treatment of acute myeloid leukaemia (AML) patients who are elderly or unfit for intensive therapy. Although effective, the complete response rate to decitabine is only around 30% and the overall survival remains poor. Emerging data support that regulation of DNA methylation is critical to control immune cell development, differentiation and activation. We hypothesize that defining how decitabine influences the immune responses in AML will facilitate the development of novel immune-based leukaemia therapeutics. Here, we performed phenotypic and functional immune analysis on clinical samples from AML patients receiving decitabine treatment and demonstrated a significant impact of decitabine on the immune system. T-cell expression of inhibitory molecules was upregulated and the ability of CD8 T cells to produce cytokines was decreased upon decitabine treatment. Importantly, in an unbiased comprehensive analysis, we identified a unique immune signature containing a cluster of key immune markers that clearly separate patients who achieved complete remission after decitabine from those who failed to do so. Therefore, this immune signature has a strong predictive value for clinical response. Collectively, our study suggests that immune-based analyses may predict clinical response to decitabine and provide a therapeutic strategy to improve the treatment of AML.

Rituximab extended schedule or retreatment trial for low tumour burden non-follicular indolent B-cell non-Hodgkin lymphomas: Eastern Cooperative Oncology Group Protocol E4402.

The rituximab extended schedule or retreatment trial (RESORT; E4402) was a phase 3 randomized prospective trial comparing maintenance rituximab (MR) versus a retreatment (RR) dosing strategy in asymptomatic, low tumour burden indolent lymphoma. A planned exploratory sub-study compared the two strategies for small lymphocytic (SLL) and marginal zone lymphomas (MZL). Patients responding to rituximab weekly × 4 were randomized to MR (single dose rituximab every 3 months until treatment failure) or RR (rituximab weekly × 4) at the time of each progression until treatment failure. The primary endpoint was time to treatment failure (TTTF). Patients with SLL (n = 57), MZL (n = 71) and unclassifiable small B-cell lymphoma (n = 3) received induction rituximab. The overall response rate (ORR) was 40% [95% confidence interval (CI) 31-49%; SLL ORR 22·8%; MZL ORR 52·1%]; all 52 responders were randomized. At a median of 4·3 years from randomization, treatment failure occurred in 18/23 RR and 15/29 MR. The median TTTF was 1·4 years for RR and 4·8 years for MR (P = 0·012); median time to first cytotoxic therapy was 6·3 years for RR and not reached for MR (P = 0·0002). Survival did not differ (P = 0·72). In low tumour burden SLL and MZL patients responding to rituximab induction, MR significantly improved TTTF as compared with RR.

CD26lowPD-1+ CD8 T cells are terminally exhausted and associated with leukemia progression in acute myeloid leukemia.

Acute myeloid leukemia (AML) is a devastating blood cancer with poor prognosis. Novel effective treatment is an urgent unmet need. Immunotherapy targeting T cell exhaustion by blocking inhibitory pathways, such as PD-1, is promising in cancer treatment. However, results from clinical studies applying PD-1 blockade to AML patients are largely disappointing. AML is highly heterogeneous. Identification of additional immune regulatory pathways and defining predictive biomarkers for treatment response are crucial to optimize the strategy. CD26 is a marker of T cell activation and involved in multiple immune processes. Here, we performed comprehensive phenotypic and functional analyses on the blood samples collected from AML patients and discovered that CD26lowPD-1+ CD8 T cells were associated with AML progression. Specifically, the percentage of this cell fraction was significantly higher in patients with newly diagnosed AML compared to that in patients achieved completed remission or healthy controls. Our subsequent studies on CD26lowPD-1+ CD8 T cells from AML patients at initial diagnosis demonstrated that this cell population highly expressed inhibitory receptors and displayed impaired cytokine production, indicating an exhaustion status. Importantly, CD26lowPD-1+ CD8 T cells carried features of terminal exhaustion, manifested by higher frequency of TEMRA differentiation, increased expression of transcription factors that are observed in terminally exhausted T cells, and high level of intracellular expression of granzyme B and perforin. Our findings suggest a prognostic and predictive value of CD26 in AML, providing pivotal information to optimize the immunotherapy for this devastating cancer.

IMPROVE-BMT: a protocol for a pilot randomised controlled trial of prehabilitation exercise for adult haematopoietic stem cell transplant recipients.

INTRODUCTION: Haematopoietic stem cell transplant (HSCT) in adults is an intensive medical procedure for a variety of haematological malignancies. Although there is a large body of evidence demonstrating the negative effects of HSCT on physical function and psychosocial parameters, there is limited evidence on the impact of HSCT on body composition and bone health. Further, aerobic and resistance-training exercise interventions aimed at improving physical function and patient-reported outcomes largely take place during the peritransplant and post-transplant period. Prehabilitative exercise, or exercise prior to medical treatment, has been successfully deployed in presurgical candidates and other tumour sites, yet there is a paucity of evidence on the effect of prehabilitation in HSCT patients. The aim of this study is to investigate the feasibility, acceptability and safety of a resistance training exercise programme in patients with haematological malignancies prior to HSCT. METHODS AND ANALYSIS: IMpact of PRehabilitation in Oncology Via Exercise-Bone Marrow Transplant is a single-site, pilot randomised controlled trial of an exercise intervention compared with usual care. The primary aim is to assess the feasibility, acceptability and safety of the resistance-training exercise intervention prior to HSCT. Secondary aims include evaluating the differences in physical function, body composition, bone mineral density and patient-reported outcomes between the exercise group and usual care control group. Outcome measurements will be assessed: prior to HSCT, on/around day of HSCT admission, +30 days post-HSCT and +100 days post-HSCT. The exercise intervention is a home-based resistance training exercise programme that incorporates resistance band and body weight exercises. The primary outcomes will be reported as percentages and/or mean values. The secondary outcomes will be analysed using appropriate statistical methods to portray within-group and between-group differences. ETHICS AND DISSEMINATION: The study has Penn State College of Medicine approval. Results will be disseminated through scientific publication and presentation at exercise-related and oncology-related scientific meetings. TRIAL REGISTRATION NUMBER: NCT03886909.

Perceived levels of pain associated with bone marrow aspirates and biopsies.

BACKGROUND: Little is known about the degree of pain experienced by patients undergoing a bone marrow aspiration and biopsy (BMAB). OBJECTIVE: To evaluate the effectiveness of several strategies aimed at reducing the pain score. METHODS: We conducted a retrospective analysis of 258 consecutive adult patients who underwent BMAB via 6 different approaches, the first 5 of which were performed by one physician. Group A received local anesthesia with 1% lidocaine hydrochloride (5 mL) and a 5-minute wait time before the procedure; group B received local anesthesia with a double dose (10 mL) of lidocaine; group C received 5 mL of local anesthesia with a 10-minute wait; group D received 5 mL of local anesthesia plus a topical spray with ethyl chloride; group E received oral analgesia and anxiolysis 30 minutes before the procedure in addition to the group A dosage of lidocaine; and group F received the same anesthesia as did group A, but the BMAD was performed by a less experienced practitioner. RESULTS: On a 0 to 10 scale, the mean pain level among the 258 patients was 3.2 (standard deviation = 2.6). Rate of complications was low (<1%). Several strategies failed to improve the pain level, including the administration of a double dose of local anesthesia, waiting longer for the anesthesia effect, and the additional use of a topical anesthetic spray or oral analgesia and anxiolysis. Pain levels were not increased when the procedure was done by a less experienced practitioner. Younger age and female gender were associated with higher pain levels. CONCLUSIONS: Given that the average level of perceived pain during BMAB is low to moderate (approximately 3 on a 0-10 scale), the routine use of conscious sedation for this procedure may not be indicated. Several strategies aimed at reducing the pain level, including doubling the dose of anesthesia and using an oral prophylactic regimen of analgesia and anxiolysis, failed to improve pain scores.

A novel clinically relevant graft-versus-leukemia model in humanized mice.

The prognosis for acute myeloid leukemia (AML) relapse post allogeneic hematopoietic stem cell transplantation (alloSCT) is dismal. Novel effective treatment is urgently needed. Clinical benefit of alloSCT greatly relies on the graft-versus-leukemia (GVL) effect. The mechanisms that mediate immune escape of leukemia (thus causing GVL failure) remain poorly understood. Studies of human GVL have been hindered by the lack of optimal clinically relevant models. Here, using our large, longitudinal clinical tissue bank that include AML cells and G-CSF mobilized donor hematopoietic stem cells (HSCs), we successfully established a novel GVL model in humanized mice. Donor HSCs were injected into immune-deficient NOD-Cg-Prkdcscid IL2rgtm1Wjl /SzJ (NSG) mice to build humanized mice. Immune reconstitution in these mice recapitulated some clinical scenario in the patient who received the corresponding HSCs. Allogeneic but HLA partially matched patient-derived AML cells were successfully engrafted in these humanized mice. Importantly, we observed a significantly reduced (yet incomplete elimination of) leukemia growth in humanized mice compared with that in control NSG mice, demonstrating a functional (but defective) GVL effect. Thus, for the first time, we established a novel humanized mouse model that can be used for studying human GVL responses against human AML cells in vivo. This novel clinically relevant model provides a valuable platform for investigating the mechanisms of human GVL and development of effective leukemia treatments.

Post-transplant cyclophosphamide alters immune signatures and leads to impaired T cell reconstitution in allogeneic hematopoietic stem cell transplant.

Despite the increased usage of post-transplant cyclophosphamide (PTCy) in allogeneic hematopoietic stem cell transplantation (allo-HSCT), our knowledge of immune reconstitution post-allo-HSCT in the setting of PTCy is limited. Adequate immune reconstitution is the key to a successful transplant. In this study, we aim to investigate the effect of PTCy on the reconstitution of each immune component; more focus was placed on the immunophenotype and functions of T cells. Using blood samples from patients who underwent allo-HSCT under regimens containing PTCy (n = 23) versus those who received no PTCy (n = 14), we examined the impact of PTCy on the post-transplant immune response. We demonstrated a distinct T cell immune signature between PTCy versus non-PTCy group. PTCy significantly delayed T cell reconstitution and affected the T cell subsets by increasing regulatory T cells (Treg) while reducing naïve T cells. In addition, we observed remarkable enhancement of multiple inhibitory receptors (TIGIT, PD-1, TIM-3, CD38, CD39) on both CD4+ and CD8+ T cells on day 30 post-transplantation in patients who received PTCy. Importantly, upregulation of PD-1 on CD8 T cells was persistent through day 180 and these T cells were less functional, manifested by reduced cytokine production upon anti-CD3/CD28 stimulation. Furthermore, we found a significant correlation of T cell immune phenotypes to clinical outcome (disease relapse and GVHD) in patients who received PTCy. Our novel findings provide critical information to understand the mechanism of how PTCy impacts immune reconstitution in allo-HSCT and may subsequently lead to optimization of our clinical practice using this treatment.

Eomes+T-betlow CD8+ T Cells Are Functionally Impaired and Are Associated with Poor Clinical Outcome in Patients with Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) is a devastating blood cancer with poor prognosis. Immunotherapy targeting inhibitory pathways to unleash the antileukemia T-cell response is a promising strategy for the treatment of leukemia, but we must first understand the underlying molecular mechanisms. Eomesodermin (Eomes) and T-bet are both T-box transcription factors that regulate CD8+ T-cell responses in a context-specific manner. Here, we examined the role of these transcription factors in CD8+ T-cell immunity in AML patients. We report that the frequency of Eomes+T-betlow CD8+ T cells increased in newly diagnosed AML. This cell subset produced fewer cytokines and displayed reduced killing capacity, whereas depletion of Eomes by siRNA reversed these functional defects. Furthermore, Eomes bound the promoter of T-cell immunoglobulin and ITIM domain (TIGIT) and positively regulated the expression of this inhibitory receptor on patient-derived T cells. A high frequency of Eomes+T-betlow CD8+ T cells was associated with poor response to induction chemotherapy and shorter overall survival in AML patients. These findings have significant clinical implications as they not only identify a predictive and prognostic biomarker for AML, but they also provide an important target for effective leukemia therapeutics. SIGNIFICANCE: These findings reveal that a high frequency of Eomes+T-betlow CD8+ T cells predicts poor clinical outcome in AML and that targeting Eomes may provide a therapeutic benefit against AML.

VISTA is highly expressed on MDSCs and mediates an inhibition of T cell response in patients with AML.

Treatment of acute myeloid leukemia (AML) remains challenging. Enhancement of anti-tumor responses by blocking negative immune regulators is a promising strategy for novel effective leukemia therapeutics. V-domain Ig suppressor of T-cell activation (VISTA) is a recently defined negative regulator mediating immune evasion in cancer. To investigate the effect of VISTA on anti-leukemia immune response in AML, we initiated a study using clinical samples collected from AML patients. Here we report that VISTA is highly expressed on myeloid-derived suppressor cells (MDSCs) in the peripheral blood of AML patients. Both the frequency and intensity of VISTA expression on MDSCs are significantly higher in newly diagnosed AML than in healthy controls. Importantly knockdown of VISTA by specific siRNA potently reduced the MDSCs-mediated inhibition of CD8 T cell activity in AML, suggesting a suppressive effect of VISTA on anti-leukemia T cell response. Furthermore, we observed a strong positive association between MDSC expression of VISTA and T cell expression of PD-1 in AML. These results support the strategy of VISTA-targeted treatment for AML and underscore the strong potential for combined blockade of VISTA and PD-1 pathways in effective leukemia control.

Blimp-1 impairs T cell function via upregulation of TIGIT and PD-1 in patients with acute myeloid leukemia.

BACKGROUND: T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT) and programmed cell death protein 1 (PD-1) are important inhibitory receptors that associate with T cell exhaustion in acute myeloid leukemia (AML). In this study, we aimed to determine the underlying transcriptional mechanisms regulating these inhibitory pathways. Specifically, we investigated the role of transcription factor B lymphocyte-induced maturation protein 1 (Blimp-1) in T cell response and transcriptional regulation of TIGIT and PD-1 in AML. METHODS: Peripheral blood samples collected from patients with AML were used in this study. Blimp-1 expression was examined by flow cytometry. The correlation of Blimp-1 expression to clinical characteristics of AML patients was analyzed. Phenotypic and functional studies of Blimp-1-expressing T cells were performed using flow cytometry-based assays. Luciferase reporter assays and ChIP assays were applied to assess direct binding and transcription activity of Blimp-1. Using siRNA to silence Blimp-1, we further elucidated the regulatory role of Blimp-1 in the TIGIT and PD-1 expression and T cell immune response. RESULTS: Blimp-1 expression is elevated in T cells from AML patients. Consistent with exhaustion, Blimp-1+ T cells upregulate multiple inhibitory receptors including PD-1 and TIGIT. In addition, they are functionally impaired manifested by low cytokine production and decreased cytotoxicity capacity. Importantly, the functional defect is reversed by inhibition of Blimp-1 via siRNA knockdown. Furthermore, Blimp-1 binds to the promoters of PD-1 and TIGIT and positively regulates their expression. CONCLUSIONS: Our study demonstrates an important inhibitory effect of Blimp-1 on T cell response in AML; thus, targeting Blimp-1 and its regulated molecules to improve the immune response may provide effective leukemia therapeutics.

PIGN gene expression aberration is associated with genomic instability and leukemic progression in acute myeloid leukemia with myelodysplastic features.

Previous studies have linked increased frequency of glycosylphosphatidylinositol-anchor protein (GPI-AP) deficiency with genomic instability and the risk of carcinogenesis. However, the underlying mechanism is still not clear. A randomForest analysis of the gene expression array data from 55 MDS patients (GSE4619) demonstrated a significant (p = 0.0007) correlation (Pearson r =-0.4068) between GPI-anchor biosynthesis gene expression and genomic instability, in which PIGN, a gene participating in GPI-AP biosynthesis, was ranked as the third most important in predicting risk of MDS progression. Furthermore, we observed that PIGN gene expression aberrations (increased transcriptional activity but diminished to no protein production) were associated with increased frequency of GPI-AP deficiency in leukemic cells during leukemic transformation/progression. PIGN gene expression aberrations were attributed to partial intron retentions between exons 14 and 15 resulting in frameshifts and premature termination which were confirmed by examining the RNA-seq data from a group of AML patients (phs001027.v1.p1). PIGN gene expression aberration correlated with the elevation of genomic instability marker expression that was independent of the TP53 regulatory pathway. Suppression/elimination of PIGN protein expression caused a similar pattern of genomic instability that was rescued by PIGN restoration. Finally, we found that PIGN bound to the spindle assembly checkpoint protein, MAD1, and regulated its expression during the cell cycle. In conclusion, PIGN gene is crucial in regulating mitotic integrity to maintain chromosomal stability and prevents leukemic transformation/progression.

Phase III randomized multicenter study of a humanized anti-CD33 monoclonal antibody, lintuzumab, in combination with chemotherapy, versus chemotherapy alone in patients with refractory or first-relapsed acute myeloid leukemia.

PURPOSE: Lintuzumab (HuM195) is an unconjugated humanized murine monoclonal antibody directed against the cell surface myelomonocytic differentiation antigen CD33. In this study, the efficacy of lintuzumab in combination with induction chemotherapy was compared with chemotherapy alone in adults with first relapsed or primary refractory acute myeloid leukemia (AML). PATIENTS AND METHODS: Patients with relapsed or primary resistant AML (duration of first response, zero to 12 months) were randomly assigned to receive either mitoxantrone 8 mg/m(2), etoposide 80 mg/m(2), and cytarabine 1 g/m(2) daily for 6 days (MEC) in combination with lintuzumab 12 mg/m(2), or MEC alone. Overall response, defined as the rate of complete remission (CR) and CR with incomplete platelet recovery (CRp), was the primary end point of the study, with additional analyses of survival time and toxicity. RESULTS: A total of 191 patients were randomly assigned from November 1999 to April 2001. The percent CR plus CRp with MEC plus lintuzumab was 36% v 28% in patients treated with MEC alone (P = .28). The overall median survival was 156 days and was not different in the two arms of the study. Apart from mild antibody infusion-related toxicities (fever, chills, and hypotension), no differences in chemotherapy-related adverse effects, including hepatic and cardiac dysfunction, were observed with the addition of lintuzumab to induction chemotherapy. CONCLUSION: The addition of lintuzumab to salvage induction chemotherapy was safe, but did not result in a statistically significant improvement in response rate or survival in patients with refractory/relapsed AML.

T-Cell Immunoglobulin and ITIM Domain (TIGIT) Associates with CD8+ T-Cell Exhaustion and Poor Clinical Outcome in AML Patients.

PURPOSE: T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT) is a recently identified T-cell coinhibitory receptor. In this study, we aimed to determine the clinical impact of TIGIT in patients with acute myelogenous leukemia (AML) and dissect the role of TIGIT in the pathogenesis of leukemia progression. EXPERIMENTAL DESIGN: TIGIT expression on T cells from peripheral blood collected from patients with AML was examined by flow cytometry. The correlation of TIGIT expression to clinical outcomes, including rate of complete remission and relapse post-allogeneic stem cell transplantation (alloSCT) in AML patients, was analyzed. Phenotypic and functional study (cytokine release, proliferation, killing, and apoptosis) of TIGIT-expressing T cells were performed. Using siRNA to silence TIGIT, we further elucidated the regulatory role of TIGIT in the T-cell immune response by dissecting the effect of TIGIT knockdown on cytokine release and apoptosis of T cells from AML patients. RESULTS: TIGIT expression on CD8(+) T cells is elevated in AML patients and high-TIGIT correlates with primary refractory disease and leukemia relapse post-alloSCT. TIGIT(+) CD8(+) T cells display phenotypic features of exhaustion and exhibit functional impairment manifested by low production of cytokines and high susceptibility to apoptosis. Importantly, their functional defects are reversed by TIGIT knockdown. CONCLUSIONS: TIGIT contributes to functional T-cell impairment and associates with poor clinical outcome in AML. Our study suggests that blockade of TIGIT to restore T-cell function and antitumor immunity may represent a novel effective leukemia therapeutic. Clin Cancer Res; 22(12); 3057-66. ©2016 AACR.

Phase I/II study of clofarabine, etoposide, and mitoxantrone in patients with refractory or relapsed acute leukemia.

BACKGROUND: Clofarabine, a second-generation nucleoside analogue, was studied in combination with etoposide and mitoxantrone in acute leukemia. PATIENTS AND METHODS: In the phase I portion of this study clofarabine was given 20 or 25 mg/m(2) daily for 5 days (Days 2-6) with etoposide 100 mg/m(2) from day 1 to 5 and mitoxantrone 8 mg/m(2) from day 1 to 3. The dose-limiting toxicity was myelosuppression, and dose level 1, with clofarabine 20 mg/m(2) daily for 5 days was identified as the phase 2 dose. In total, 22 patients with relapsed or refractory acute myeloid leukemia (n = 18) and acute lymphocytic leukemia (n = 4) were treated. RESULTS: Five of 22 patients (23%) achieved complete response (CR), and 3 (13%) achieved CR with incomplete platelet recovery; an overall response rate of 36%. Median overall survival was 167 days (range, 22-1327 days). For 2 patients this regimen represented an effective bridge to allogeneic stem cell transplantation. CONCLUSION: Clofarabine in combination with etoposide and mitoxantrone is tolerable and shows significant activity in relapsed and refractory acute leukemia in adults.

A phase 2 study of inotuzumab ozogamicin and rituximab, followed by autologous stem cell transplant in patients with relapsed/refractory diffuse large B-cell lymphoma.

This study evaluated the safety and efficacy of inotuzumab ozogamicin (INO), a targeted humanized anti-CD22 antibody conjugated to calicheamicin, plus rituximab (R-INO) every 3 weeks, up to six cycles, followed by high dose therapy and autologous stem cell transplant (HDT-aSCT) in patients with high-risk relapsed/refractory diffuse large B-cell lymphoma (DLBCL). The primary endpoint was overall response (OR) rate after three cycles of R-INO. Sixty-three patients were enrolled. Common grade 3/4 adverse events during R-INO treatment were thrombocytopenia, lymphopenia and neutropenia. OR rate after three cycles of R-INO was 28.6% (95% confidence interval: 17.9-41.4). Eighteen patients underwent HDT-aSCT; 2-year progression-free survival (PFS) for these patients was 61.1%. Serious infections and hepatic toxicity following aSCT occurred in 33% and 22%, respectively. One- and 2-year PFS rates for all enrolled patients were 28.9% and 25.3%, respectively (median, 3.0 months). R-INO had lower than expected activity as a salvage regimen for transplant eligible patients with DLBCL.

Lacunar and reed-sternberg-like cells in follicular lymphomas are clonally related to the centrocytic and centroblastic cells as demonstrated by laser capture microdissection.

Two cases of follicular lymphoma (FL) with numerous large cells resembling the lacunar and Hodgkin and Reed-Sternberg (HRS) cells of classic Hodgkin lymphoma were studied to determine clonal relationships between the HRS-like cells and centrocytic and centroblastic (CCCB) cells. In both cases, CCCB cells were typical of FL; CD45RB, CD20, CD10 and BCL-2 positive. In case 1, the HRS-like cells were positive for CD45RB, CD20, CD10, CD30, OCT2, and BOB.1 and negative for CD15 and bcl-2. In case 2, the HRS-like cells were positive for CD30, fascin, CD20, OCT2, and BOB.1 and negative for CD45RB, CD10, CD15, and bcl-2. CCCB and single HRS-like cells were isolated by laser capture microdissection followed by polymerase chain reaction amplification and sequencing of immunoglobulin heavy chain gene rearrangements. In both cases, identical sequences were obtained from CCCB and HRS-like cells. These findings confirm that although the HRS cells and CCCB cells in these cases demonstrate morphologic and immunophenotypic divergence, they share a common cell of origin. These cases further highlight the potential diagnostic pitfall presented by FL with HRS-like cells.

Rituximab extended schedule or re-treatment trial for low-tumor burden follicular lymphoma: eastern cooperative oncology group protocol e4402.

PURPOSE: In low-tumor burden follicular lymphoma (FL), maintenance rituximab (MR) has been shown to improve progression-free survival when compared with observation. It is not known whether MR provides superior long-term disease control compared with re-treatment rituximab (RR) administered on an as-needed basis. E4402 (RESORT) was a randomized clinical trial designed to compare MR against RR. PATIENTS AND METHODS: Eligible patients with previously untreated low-tumor burden FL received four doses of rituximab, and responding patients were randomly assigned to either RR or MR. Patients receiving RR were eligible for re-treatment at each disease progression until treatment failure. Patients assigned to MR received a single dose of rituximab every 3 months until treatment failure. The primary end point was time to treatment failure. Secondary end points included time to first cytotoxic therapy, toxicity, and health-related quality of life (HRQOL). RESULTS: A total of 289 patients were randomly assigned to RR or MR. With a median follow-up of 4.5 years, the estimated median time to treatment failure was 3.9 years for patients receiving RR and 4.3 years for those receiving MR (P = .54). Three-year freedom from cytotoxic therapy was 84% for those receiving RR and 95% for those receiving MR (P = .03). The median number of rituximab doses was four patients receiving RR and 18 for those receiving MR. There was no difference in HRQOL. Grade 3 to 4 toxicities were infrequent in both arms. CONCLUSION: In low-tumor burden FL, a re-treatment strategy uses less rituximab while providing disease control comparable to that achieved with a maintenance strategy.