Nivolumab receptor occupancy on effector regulatory T cells predicts clinical benefit.

Immune checkpoint inhibitor discovery represents a turning point in cancer treatment. However, the response rates of solid tumors remain ~10%-30%; consequently, prognostic and immune-related adverse event (irAE) predictors are being explored. The programmed cell death protein 1 (PD-1) receptor occupancy (RO) of PD-1 inhibitors depends on the number of peripheral blood lymphocytes and their PD-1 expression levels, suggesting that the RO may be related to efficacy and adverse events. As PD-1 inhibition affects each T-cell subset differently, the RO of each cell population must be characterized. However, relevant data have not been reported, and the prognostic relevance of this parameter is not known. In this study, we aimed to clarify the association between the nivolumab RO in each T-cell population and patient prognosis and reveal the development of irAEs in nivolumab-treated patients. Thirty-two patients were included in the study, and the mean follow-up period was 364 days. The nivolumab RO on effector regulatory T cells (eTregs) was significantly lower in the group that presented clinical benefits, and a significant negative association was observed between PD-1 occupancy on eTregs and all-cause mortality. The results suggest that the nivolumab RO on eTregs may be a prognostic factor in PD-1 inhibitor therapy, implying that the inhibition of PD-1/PD-ligand 1 (PD-L1) signaling on eTregs may attenuate antitumor effects.

Butyricimonas is a key gut microbiome component for predicting postoperative recurrence of esophageal cancer.

BACKGROUND: Recently, intestinal bacteria have attracted attention as factors affecting the prognosis of patients with cancer. However, the intestinal microbiome is composed of several hundred types of bacteria, necessitating the development of an analytical method that can allow the use of this information as a highly accurate biomarker. In this study, we investigated whether the preoperative intestinal bacterial profile in patients with esophageal cancer who underwent surgery after preoperative chemotherapy could be used as a biomarker of postoperative recurrence of esophageal cancer. METHODS: We determined the gut microbiome of the patients using 16S rRNA metagenome sequencing, followed by statistical analysis. Simultaneously, we performed a machine learning analysis using a random forest model with hyperparameter tuning and compared the data obtained. RESULTS: Statistical and machine learning analyses revealed two common bacterial genera, Butyricimonas and Actinomyces, which were abundant in cases with recurrent esophageal cancer. Butyricimonas primarily produces butyrate, whereas Actinomyces are oral bacteria whose function in the gut is unknown. CONCLUSION: Our results indicate that Butyricimonas spp. may be a biomarker of postoperative recurrence of esophageal cancer. Although the extent of the involvement of these bacteria in immune regulation remains unknown, future research should investigate their presence in other pathological conditions. Such research could potentially lead to a better understanding of the immunological impact of these bacteria on patients with cancer and their application as biomarkers.

FGFR2 loss sensitizes MYCN-amplified neuroblastoma CHP134 cells to CHK1 inhibitor-induced apoptosis.

Checkpoint kinase 1 (CHK1) plays a key role in genome surveillance and integrity throughout the cell cycle. Selective inhibitors of CHK1 (CHK1i) are undergoing clinical evaluation for various human malignancies, including neuroblastoma. In this study, one CHK1i-sensitive neuroblastoma cell line, CHP134, was investigated, which characteristically carries MYCN amplification and a chromosome deletion within the 10q region. Among several cancer-related genes in the chromosome 10q region, mRNA expression of fibroblast growth factor receptor 2 (FGFR2) was altered in CHP134 cells and associated with an unfavorable prognosis of patients with neuroblastoma. Induced expression of FGFR2 in CHP134 cells reactivated downstream MEK/ERK signaling and resulted in cells resistant to CHK1i-mediated cell growth inhibition. Consistently, the MEK1/2 inhibitor, trametinib, potentiated CHK1 inhibitor-mediated cell death in these cells. These results suggested that FGFR2 loss might be prone to highly effective CHK1i treatment. In conclusion, extreme cellular dependency of ERK activation may imply a possible application for the MEK1/2 inhibitor, either as a single inhibitor or in combination with CHK1i in MYCN-amplified neuroblastomas.

HLA 1-3 antigen-mismatched related peripheral blood stem cells transplantation using low-dose antithymocyte globulin versus unrelated cord blood transplantation.

Little information is available regarding whether unrelated cord blood transplantation (CBT) or an HLA 1-3 antigen-mismatched related donor peripheral blood stem-cell transplantation (PBSCT) using low-dose anti-thymocyte globulin (ATG) is superior as an alternative transplantation for patients who lack an HLA-matched sibling or unrelated donor. Therefore, we evaluated 7861 patients with hematologic malignancies (aged 0 to 70 years) who received either a CBT without ATG (CBT-no ATG, n = 7034) or an HLA 1-3 antigen-mismatched related donor PBSCT using low-dose ATG (PBSCT-ATG, n = 827). CBT-no ATG was associated with significantly better overall survival (OS) than the use of a PBSCT-ATG (hazard ratio [HR], 0.77; p < .001), although PBSCT-ATG patients with an HLA 1 antigen-mismatch showed OS comparable to that in the CBT-no ATG group. Neutrophil and platelet engraftment was significantly delayed, whereas the incidences of nonrelapse mortality, and severe graft-versus-host disease (GVHD) were significantly lower in the CBT-no ATG group. The incidences of relapse and chronic GVHD were comparable between these donors. In conclusion, CBT-no ATG may be a better alternative than HLA-mismatched related donor PBSCT using low-dose ATG. Notably, HLA 2-3 antigen mismatch-related transplantation with low-dose ATG had significant adverse effects on transplantation outcomes.

The Prognostic Impact of MYC Gene-Related Abnormalities on Multiple Myeloma Outcome through Fluorescence in situ Hybridization Analysis.

INTRODUCTION: Chromosomal abnormalities (CAs) have been identified as important factors in determining the biological features and prognostic value of multiple myeloma (MM). MYC gene-related abnormalities (MYC GAs) are one of the CAs, but their unfavorable impact has not been fully investigated in daily clinical practice. METHODS: This study retrospectively analyzed the prognostic impact of MYC GAs on 81 patients through fluorescence in situ hybridization analysis in our institute. RESULTS: MYC GAs were associated with poor overall survival (hazard ratio [HR], 3.08; 95% confidence interval [CI]: 1.23-7.73; p = 0.017), progression-free survival (PFS) (HR, 2.96; 95% CI: 1.58-5.53; p < 0.001), and time to next treatment (TNT) (HR, 2.11; 95% CI: 1.13-3.93; p = 0.018) in the median follow-up of 34.7 months. Furthermore, MYC GAs with an additional chromosome 8 (MYC-Ch8(+)) were associated with shorter PFS (HR, 3.15; 95% CI: 1.38-7.2; p = 0.0064), whereas MYC GAs without an additional chromosome 8 (MYC-Ch8(-)) were associated with shorter PFS (HR, 3.62; 95% CI: 1.51-8.68; p = 0.004) and shorter TNT (HR, 3.72; 95% CI: 1.41-9.81; p = 0.0078). CONCLUSION: These findings could help identify high-risk patients with MM. Further prospective studies are needed to confirm the significance of MYC GAs for the MM prognostic effect.

The Sympathetic Nervous System Contributes to the Establishment of Pre-Metastatic Pulmonary Microenvironments.

Emerging evidence suggests that neural activity contributes to tumor initiation and its acquisition of metastatic properties. More specifically, it has been reported that the sympathetic nervous system regulates tumor angiogenesis, tumor growth, and metastasis. The function of the sympathetic nervous system in primary tumors has been gradually elucidated. However, its functions in pre-metastatic environments and/or the preparation of metastatic environments far from the primary sites are still unknown. To investigate the role of the sympathetic nervous system in pre-metastatic environments, we performed chemical sympathectomy using 6-OHDA in mice and observed a decrease in lung metastasis by attenuating the recruitment of myeloid-derived suppressor cells. Furthermore, we note that neuro-immune cell interactions could be observed in tumor-bearing mouse lungs in conjunction with the decreased expression of Sema3A. These data indicate that the sympathetic nervous system contributes to the preparation of pre-metastatic microenvironments in the lungs, which are mediated by neuro-immune cell interactions.

[Isolated central nervous system relapse of Philadelphia chromosome-positive acute lymphoblastic leukemia during ponatinib maintenance therapy].

A 65-year-old man was diagnosed with Philadelphia chromosome-positive acute lymphoblastic leukemia with no initial central nervous system (CNS) involvement. Complete remission was achieved after the induction therapy. However, during consolidation therapy, he developed septic shock and pneumocystis pneumonia, leading to interruption in chemotherapy and allogeneic transplantation. Subsequently, he achieved complete molecular remission and ponatinib maintenance therapy was initiated. Two years later, he developed left leg paralysis and was diagnosed with isolated CNS relapse; however, radiation therapy improved CNS lesions and paralysis. Thus, ponatinib maintenance therapy alone is inadequate in preventing CNS relapse in patients who have not completed systemic chemotherapy for CNS relapse prevention.

[Successful treatment of secondary graft failure after allogeneic stem cell transplantation for aplastic anemia with eltrombopag].

Herein we report a case of successful treatment of secondary graft failure due to poor graft function (PGF) using eltrombopag. A 25-year-old woman with aplastic anemia (stage 3) underwent allogeneic bone marrow transplantation (BMT) from her HLA-matched brother. Neutrophil engraftment was achieved on day 17, but she remained dependent on platelet transfusion. Chimerism analysis showed complete donor type, but she also became dependent on red blood cell transfusion later. Eltrombopag was administered on day 253 after BMT, after which she exhibited hematopoietic recovery, resulting in the withdrawal of transfusion dependency. Blood counts continued to be stable after eltrombopag was discontinued. The use of eltrombopag enabled outpatient treatment and induced hematopoietic recovery without significant side effects. Eltrombopag may be an effective and safe option for PGF after BMT.

A high number of PD-L1+ CD14+ monocytes in peripheral blood is correlated with shorter survival in patients receiving immune checkpoint inhibitors.

PURPOSE: Targeting of anti-programmed cell death protein-1 (PD-1) and anti-programmed death-ligand 1 (PD-L1) is a standard therapeutic strategy for various cancers. The aim of the present study was to investigate the prognostic effect of pretreatment PD-L1 expression levels in peripheral blood mononuclear cell (PBMC) subsets for patients with several cancer types receiving anti-PD-1 blockade therapies. PATIENTS AND METHODS: Thirty-two patients undergoing anti-PD-L1 blockade therapy, including 15 with non-small cell lung cancer, 14 with gastric cancer, 1 with melanoma, 1 with parotid cancer, and 1 with bladder cancer, were recruited for the present study. PD-L1 expression levels in CD3+, CD4+, CD8+, CD45RA+ and CCR7+ T cells; CD20+ B cells; CD14+ and CD16+ monocytes were measured via flow cytometry before treatment. The percentages of PD-L1+ cells in respective PBMC subsets were compared with respect to different clinicopathological conditions and the association with overall survival (OS) was assessed. RESULTS: The percentages of PD-L1+ with CD3+, CD4+ and CD8+ T cells including naïve and memory T cell subsets, or CD20+ B cells during pretreatment were not markedly correlated with the OS of patients (p > 0.05); however, the percentage of the PD-L1+ CD14+ monocyte subset was significantly correlated with OS (p = 0.0426). CONCLUSION: Increase in pretreatment expression levels of PD-L1 on CD14+ monocytes is associated with the OS of patients treated with immune checkpoint inhibitors. Further evaluation of large sample size and each specific cancer type might clarify the predictive role of PBMC in patients.

Increased SLAMF7high monocytes in myelofibrosis patients harboring JAK2V617F provide a therapeutic target of elotuzumab.

Monocyte-derived fibrocytes recently garnered attention because the novel pathogenesis of myelofibrosis (MF), and suppression of fibrocyte differentiation by serum amyloid P remarkably improved MF. We previously revealed that human fibrocytes highly expressed signaling lymphocytic activation molecule F7 (SLAMF7) compared with macrophages and that SLAMF7high monocytes in the peripheral blood (PB) of MF patients were significantly elevated relative to those in healthy controls (HCs). In this study, we evaluated SLAMF7high monocyte percentage in the PB of HCs, myeloproliferative neoplasm (MPN) patients with MF, and MPN patients without MF by using a cross-sectional approach. We found that MPN patients with MF who harbored JAK2V617F had a significantly elevated SLAMF7high monocyte percentage, which correlated positively with the JAK2V617F allele burden. In addition, the serum concentration of interleukin-1ra (IL-1ra) was significantly correlated with the SLAMF7high monocyte percentage and JAK2V617F allele burden. These findings suggest that both SLAMF7high monocytes and IL-1ra could be useful noninvasive markers of MF onset. Furthermore, the JAK2V617F allele burden of SLAMF7high monocytes was significantly higher than that of SLAMF7low monocytes and could be a potential target of elotuzumab (Elo), an anti-SLAMF7 antibody used for treating multiple myeloma. Elo independently inhibited differentiation of fibrocytes derived not only from HCs but also from MF patients in vitro. Elo also ameliorated MF and splenomegaly induced by romiplostim administration in humanized NOG mice. In conclusion, an increase of SLAMF7high monocytes with higher JAK2V617F allele burden was associated with the onset of MF in MPN patients harboring JAK2V617F, and Elo could be a therapeutic agent for MPN patients with MF who harbor JAK2V617F.

Analysis of ADAM12-Mediated Ephrin-A1 Cleavage and Its Biological Functions.

Accumulating evidence indicates that an elevated ephrin-A1 expression is positively correlated with a worse prognosis in some cancers such as colon and liver cancer. The detailed mechanism of an elevated ephrin-A1 expression in a worse prognosis still remains to be fully elucidated. We previously reported that ADAM12-cleaved ephrin-A1 enhanced lung vascular permeability and thereby induced lung metastasis. However, it is still unclear whether or not cleaved forms of ephrin-A1 are derived from primary tumors and have biological activities. We identified the ADAM12-mediated cleavage site of ephrin-A1 by a Matrix-assisted laser desorption ionization mass spectrometry and checked levels of ephrin-A1 in the serum and the urine derived from the primary tumors by using a mouse model. We found elevated levels of tumor-derived ephrin-A1 in the serum and the urine in the tumor-bearing mice. Moreover, inhibition of ADAM-mediated cleavage of ephrin-A1 or antagonization of the EphA receptors resulted in a significant reduction of lung metastasis. The results suggest that tumor-derived ephrin-A1 is not only a potential biomarker to predict lung metastasis from the primary tumor highly expressing ephrin-A1 but also a therapeutic target of lung metastasis.

[Spontaneous resolution of refractory ascites in the late phase after cord blood transplantation in acute myeloid leukemia].

Patients with refractory ascites that develops >3 months after allogenic stem cell transplantation typically have a poor prognosis. We present the case of a 61-year-old man who developed refractory massive ascites approximately 3 months after cord blood transplantation (CBT) and showed complete and spontaneous remission from ascites after 18 months. The patient complained of severe bloating and needed weekly paracentesis to manage the fluid levels. Laboratory tests indicated that the ascites was caused by liver fibrosis. After the patient underwent Keisuke-Matsusaki cell-free and concentrated ascites reinfusion therapy (KM-CART), we were able to decrease the frequency of paracentesis treatments. We planned a transjugular liver biopsy, but the patient contracted pneumocystis pneumonia before the procedure could be performed. Although the pneumonia improved, the ascites worsened again. However, weekly paracentesis spontaneously stopped the progression of ascites and eventually resolved it completely, resulting in the patient's survival.

Improvement of early mortality in single-unit cord blood transplantation for Japanese adults from 1998 to 2017.

The major limitation of cord blood transplantation (CBT) for adults remains the delayed hematopoietic recovery and higher incidence of graft failure, which result in a higher risk of early mortality in CBT. We evaluated early overall survival (OS), non-relapse mortality (NRM), neutrophil engraftment, acute graft-vs-host disease, and cause of early death among 9678 adult patients who received single-unit CBT in Japan between 1998 and 2017. The probability of OS at 100 days was 64.4%, 71.7%, and 78.9% for the periods 1998 to 2007, 2008 to 2012, and 2013 to 2017, respectively (P < .001). The cumulative incidences of NRM at 100 days during the same period were 28.3%, 20.8%, and 14.6%, respectively (P < .001). The cumulative incidences of neutrophil engraftment were also improved during the same period (P < .001). The most common cause of death within 100 days after CBT was bacterial infection in 1998 to 2007 and primary disease in the latter two time periods. Across the three time periods, the proportions of deaths from bacterial and fungal infection, graft failure, hemorrhage, sinusoidal obstructive syndrome, and organ failure decreased in a stepwise fashion. Landmark analysis of OS and NRM after 100 days showed that OS did not change over time in the multivariate analysis. Our registry-based data demonstrated a significant improvement of early OS after CBT for adults over the past 20 years. The landmark analysis suggested that improvement of early mortality could lead to an improvement of long-term OS after CBT.

[Bendamustine and rituximab combination therapy for recurrent indolent B-cell lymphomas: a retrospective single-institution study].

This retrospective study evaluated the outcomes of patients treated with combination of bendamustine and rituximab (BR) for recurrent indolent B-cell lymphoma from January 2011 to February 2018 in our department. The cohort included 36 males and 27 females, and majority of the patients (59%) were between 51 and 70 years of age. The disease types were follicular lymphoma (FL) and mantle-cell lymphoma in 42 (67%) and 15 (24%) patients, respectively. Median progression-free survival (PFS) was not reached in patients with FL who completed BR therapy. The analysis of patients who received BR therapy revealed that the number of CD4-positive lymphocytes remained around 200/µl even five years after the end of treatment. BR therapy was a useful treatment option for recurrent indolent B-cell lymphoma, especially in patients with FL, and completion of BR therapy appeared to be important for improved PFS. Furthermore, attention should be paid for potential infections for at least five years after BR therapy because cell-mediated immunodeficiency may become apparent after treatment.

[VEGF secretion from Epstein-Barr virus-infected cells as a cause of severe anasarca in a patient with angioimmunoblastic T-cell lymphoma].

A 69-year-old woman presented to National Defense Medical College hospital for suspected nephrotic syndrome due to weight gain of 30 kg in 3 weeks and bilateral lower leg edema. However, her urinalysis showed microproteinuria, which excluded nephrotic syndrome. Computed tomography revealed severe systemic edema, pleural effusion, ascites, and enlarged cervical and axillary lymph nodes. Histological examination of axillary lymph node specimen showed a typical architecture of angioimmunoblastic T-cell lymphoma. One course of CHOP chemotherapy regimen was administered which improved the lymph nodes and systemic edema. The patient achieved complete remission after 6 courses of CHOP. Because serum vascular endothelial growth factor (VEGF) level was elevated before the treatment and normalized after the treatment, increased vascular permeability mediated by VEGF was hypothesized to have caused the systemic edema. In addition, VEGF secretion from Epstein-Barr virus (EBV)-infected cells was likely associated with the patient's clinical condition because B lymphocytes stained with CD20 were positive for Epstein-Barr virus-encoded small RNAs (EBERs) and VEGF.

A first-in-human phase 1 study of ACE910, a novel factor VIII-mimetic bispecific antibody, in healthy subjects.

ACE910 is a recombinant humanized bispecific antibody that binds to activated factor IX and factor X and mimics the cofactor function of factor VIII (FVIII). This first-in-human study examined the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of ACE910 in healthy male adults. A total of 40 Japanese and 24 white subjects were randomized to receive a single subcutaneous injection of ACE910 (Japanese: 0.001, 0.01, 0.1, 0.3, or 1 mg/kg; white: 0.1, 0.3, or 1 mg/kg; n = 6 per dose group) or placebo (n = 2 per dose group). ACE910 exhibited a linear PK profile and had a half-life of ∼4 to 5 weeks. In FVIII-neutralized plasma, ACE910 shortened activated partial thromboplastin time and increased peak height of thrombin generation in a dose-dependent manner. All adverse events were nonserious and did not lead to any subject's withdrawal. Neither clinical findings nor laboratory abnormalities indicating hypercoagulability were observed. Two of 48 subjects receiving ACE910 (1 Japanese and 1 white) were positive for anti-ACE910 antibodies (anti-drug antibodies [ADAs]). One subject tested positive for ADAs both before and after ACE910 administration, whereas the other became ADA positive after receiving ACE910. The PK and PD profiles of ACE910 were similar in healthy Japanese and white subjects and suggest that ACE910 will be an effective and convenient prophylactic treatment of hemophilia A. This trial was registered at www.clinicaltrials.jp as #JapicCTI-121934.

Evaluation of CYP2D6 Protein Expression and Activity in the Small Intestine to Determine Its Metabolic Capability in the Japanese Population.

CYP2D6 plays an important role in the metabolism of many drugs such as opioids and antidepressants. Polymorphisms of the CYP2D6 gene are widely observed in the Japanese population, and can affect the first-pass metabolism of orally administered drugs. Several CYP enzymes have been identified in the small intestine of Caucasians, but intestinal CYP enzymes have not been reported in the Japanese population, except for CYP3A4 and CYP2C19. In this study, we evaluated the CYP2D6 metabolic capacity by measurement of CYP2D6 mRNA and protein levels and activity in the small intestine of Japanese individuals. Normal jejunal tissues were obtained from 31 patients who had undergone pancreaticoduodenectomy, and the CYP2D6*10 variant was identified in these tissues. CYP2D6 mRNA and CYP2D6 protein levels were analyzed using real-time RT-PCR and Western blotting, respectively. Bufuralol 1'-hydroxylation, a marker of CYP2D6 activity, was analyzed using HPLC. Frequencies of the CYP2D6*1/*1, *1/*10, and *10/*10 genotypes in the jejunal tissue were 29.0% (n=9), 35.5% (n=11), and 35.5% (n=11), respectively. CYP2D6 protein and activity levels did not differ significantly between the genotypes. A positive correlation was found between CYP2D6 protein and activity levels. Furthermore, CYP2D6 protein levels and activity in the small intestine were significantly lower than those in the liver. These findings suggest that the metabolic capacity of CYP2D6 in the small intestine of the Japanese population has a relatively small effect on drug metabolism.

Molecular epidemiology of enteric viruses in patients with acute gastroenteritis in Aichi prefecture, Japan, 2008/09-2013/14.

Acute gastroenteritis is a critical infectious disease that affects infants and young children throughout the world, including Japan. This retrospective study was conducted from September 2008 to August 2014 (six seasons: 2008/09-2013/14) to investigate the incidence of enteric viruses responsible for 1,871 cases of acute gastroenteritis in Aichi prefecture, Japan. Of the 1,871 cases, 1,100 enteric viruses were detected in 978 samples, of which strains from norovirus (NoV) genogroup II (60.9%) were the most commonly detected, followed by strains of rotavirus A (RVA) (23.2%), adenovirus (AdV) type 41 (8.2%), sapovirus (SaV) (3.6%), human astrovirus (HAstV) (2.8%), and NoV genogroup I (1.3%). Sequencing of the NoV genogroup II (GII) strains revealed that GII.4 was the most common genotype, although four different GII.4 variants were also identified. The most common G-genotype of RVA was G1 (63.9%), followed by G3 (27.1%), G2 (4.7%) and G9 (4.3%). Three genogroups of SaV strains were found: GI (80.0%), GII (15.0%), and GV (5.0%). HAstV strains were genotyped as HAstV-1 (80.6%), HAstV-8 (16.1%), and HAstV-3 (3.2%). These results show that NoV GII was the leading cause of sporadic acute viral gastroenteritis, although a variety of enteric viruses were detected during the six-season surveillance period.

Second-generation total synthesis of aplyronine A featuring Ni/Cr-mediated coupling reactions.

Second-generation total synthesis of aplyronine A, a potent antitumor marine macrolide, was achieved using Ni/Cr-mediated coupling reactions as key steps. The overall yield of the second-generation synthetic pathway of aplyronine A was 1.4%, obtained in 38 steps based on the longest linear sequence. Compared to our first-generation synthetic pathway of aplyronine A, the second-generation synthesis greatly improved both the yield and number of steps. In particular, we improved the stereoselectivity in the construction of the C13 stereogenic center and the C14-C15 (E)-trisubstituted double bond using the asymmetric Ni/Cr-mediated coupling reaction. Furthermore, we established efficient reaction conditions for the asymmetric Ni/Cr-mediated coupling reaction between the C21-C28 segment and C29-C34 segment. Thus, this coupling reaction proceeded with an equimolar ratio of each segment.

Concurrent intestinal plasmablastic lymphoma and diffuse large B-cell lymphoma with a clonal relationship: a case report and literature review.

Herein, we report a case of plasmablastic lymphoma (PBL) and diffuse large B-cell lymphoma (DLBCL) that occurred concurrently in the large intestine. An 84-year-old female presented with a palpable rectal tumor and ileocecal tumor observed on imaging analyses. Endoscopic biopsy of both lesions revealed lymphomatous round cells. Hartmann's operation and ileocecal resection were performed for regional control. The ileocecal lesion consisted of a proliferation of CD20/CD79a-positive lymphoid cells, indicative of DLBCL. In contrast, the rectal tumor showed proliferation of atypical cells with pleomorphic nuclei and abundant amphophilic cytoplasm, with immunohistochemical findings of CD38/CD79a/MUM1/MYC (+) and CD20/CD3/CD138/PAX5 (-). Tumor cells were positive for Epstein-Barr virus- encoded RNA based on in situ hybridization and MYC rearrangement in fluorescence in situ hybridization analysis. These findings indicated the rectal tumor was most likely a PBL. Sequencing analysis for immunoglobulin heavy variable genes indicated a common B-cell origin of the two sets of lymphoma cells. This case report and literature review provide new insights into PBL tumorigenesis.