A phase II Japanese trial of 90-minute rituximab infusion for untreated B-cell lymphoma.

OBJECTIVE: This phase II clinical trial evaluated feasibility and tolerability of 90-minute rituximab infusion and a concentration of 4 mg/mL rituximab infusion in Japanese patients with previously untreated follicular lymphoma or diffuse large B-cell lymphoma. METHODS: Treatment was rituximab with cyclophosphamide, doxorubicin, vincristine and prednisolone. In cycle 1, rituximab at a dose of 375 mg/m2 (4 mg/mL) was administered at the standard infusion rate stipulated in the package insert. On confirmed tolerance of rituximab, patients received 90-minute infusion in second and subsequent cycles. The primary endpoint was incidence of grade 3 or higher infusion-related reactions during 90-minute rituximab infusion in cycle 2 of rituximab with cyclophosphamide, doxorubicin, vincristine and prednisolone. RESULTS: All 32 patients (median age 61.5 years, 16 males, 24 with diffuse large B-cell lymphoma) completed the prescribed six or eight cycles of treatment. One patient withdrew consent after cycle 1, and another developed grade 2 erythema and continued receiving 4 mg/mL at the standard infusion rate for cycle 2. The remaining 30 patients received 90-minute rituximab infusion; 28 (93.3%) completed cycle 2 at the scheduled infusion rate and dosage. No grade 3 or higher infusion-related reactions were associated with a concentration of 4 mg/mL rituximab dose or 90-min rituximab infusion in cycle 2. The most common infusion-related reaction symptoms were pruritus, hypertension and oropharyngeal discomfort. During the study, toxicities and adverse events were as expected, with no new safety signals. CONCLUSION: High-concentration dosing (4 mg/mL) and 90-minute infusion of rituximab are feasible and tolerable in Japanese patients with previously untreated follicular lymphoma or diffuse large B-cell lymphoma. CLINICAL TRIAL NUMBER: JapicCTI-173 663.

Early dynamics of chronic myeloid leukemia on nilotinib predicts deep molecular response.

Chronic myeloid leukemia (CML) is a myeloproliferative disorder caused by the BCR-ABL1 tyrosine kinase. Although ABL1-specific tyrosine kinase inhibitors (TKIs) including nilotinib have dramatically improved the prognosis of patients with CML, the TKI efficacy depends on the individual patient. In this work, we found that the patients with different nilotinib responses can be classified by using the estimated parameters of our simple dynamical model with two common laboratory findings. Furthermore, our proposed method identified patients who failed to achieve a treatment goal with high fidelity according to the data collected only at three initial time points during nilotinib therapy. Since our model relies on the general properties of TKI response, our framework would be applicable to CML patients who receive frontline nilotinib or other TKIs.

Phase II study of E7777 in Japanese patients with relapsed/refractory peripheral and cutaneous T-cell lymphoma.

E7777 is a recombinant cytotoxic fusion protein composed of the diphtheria toxin fragments A and B and human interleukin-2. It shares an amino acid sequence with denileukin diftitox, but has improved purity and an increased percentage of active monomer. We undertook a multicenter, single-arm phase II study of E7777 in patients with relapsed or refractory peripheral T-cell lymphoma (PTCL) and cutaneous T-cell lymphoma (CTCL) to evaluate its efficacy, safety, pharmacokinetics, and immunogenicity. A total of 37 patients were enrolled, of which 17 and 19 patients had PTCL and CTCL, respectively, and one patient with another type of lymphoma (extranodal natural killer/T-cell lymphoma, nasal type), diagnosed by the Central Pathological Diagnosis Committee. Among the 36 patients with PTCL and CTCL, objective response rate based on the independent review was 36% (41% and 31%, respectively). The median progression-free survival was 3.1 months (2.1 months in PTCL and 4.2 months in CTCL). The common adverse events (AEs) observed were increased aspartate aminotransferase (AST) / alanine aminotransferase (ALT), hypoalbuminemia, lymphopenia, and pyrexia. Our results indicated that a 9 µg/kg/d dose of E7777 shows efficacy and a manageable safety profile in Japanese patients with relapsed or refractory PTCL and CTCL, with clinical activity observed across the range of CD25 expression. The common AEs were manageable, but increase in ALT / AST, hypoalbuminemia, and capillary leak syndrome should be carefully managed during the treatment.

Prophylactic antiviral therapy for hepatitis B virus surface antigen-positive patients with diffuse large B-cell lymphoma treated with rituximab-containing chemotherapy.

We conducted a nationwide retrospective analysis of 116 hepatitis B virus (HBV) surface antigen (HBsAg)-positive patients with diffuse large B-cell lymphoma (DLBCL) and 278 HBsAg-negative patients with DLBCL, as a control cohort, who received rituximab-containing regimens as an induction chemotherapy at 30 Japanese medical centers between January 2004 and December 2014. Hepatitis was defined as an absolute serum alanine aminotransferase (ALT) level of ≥100 U/L. HBV reactivation-related hepatitis was defined as hepatitis with an absolute serum HBV DNA level of ≥3.3 log IU/mL or an absolute increase of ≥2 log compared with the baseline value. HBsAg-positive patients were divided into three groups based on anti-HBV prophylactic therapy: no nucleos(t)ide analogue (non-NA, n = 9), lamivudine (LAM, n = 20), and entecavir (ETV, n = 87). The 4-year cumulative incidence (CI) of hepatitis in HBsAg-positive and HBsAg-negative patients was 21.1% and 14.6% (P = .081), respectively. The 4-year CI of HBV reactivation-related hepatitis was higher in HBsAg-positive patients than in HBsAg-negative patients (8.0% vs 0.4%; P < .001). Among HBsAg-positive patients, the 4-year CI of HBV reactivation-related hepatitis was the highest in the non-NA group (33.3%), followed by the LAM (15.0%) and ETV (3.8%) groups (P < .001). Of note, 3 non-NA patients (33%) and 1 LAM patient (5%) (but no ETV patients) died due to HBV hepatitis. Based on Cox multivariate analysis, HBsAg positivity was not associated with poor overall survival. Prophylactic use of ETV would reduce the occurrence of HBV reactivation-related hepatitis and mortality in HBsAg-positive DLBCL patients receiving rituximab-containing chemotherapy.

DA-EPOCH-R combined with high-dose methotrexate in patients with newly diagnosed stage II-IV CD5-positive diffuse large B-cell lymphoma: a single-arm, open-label, phase II study.

CD5-positive diffuse large B-cell lymphoma (CD5+ DLBCL) is characterized by poor prognosis and a high frequency of central nervous system relapse after standard immunochemotherapy. We conducted a phase II study to investigate the efficacy and safety of dose-adjusted (DA)- EPOCH-R (etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab) combined with high-dose methotrexate (HD-MTX) in newly diagnosed patients with CD5+ DLBCL. Previously untreated patients with stage II to IV CD5+ DLBCL according to the 2008 World Health Organization classification were eligible. Four cycles of DA-EPOCH-R followed by two cycles of HD-MTX and four additional cycles of DAEPOCH- R (DA-EPOCH-R/HD-MTX) were planned as the protocol treatment. The primary end point was 2-year progression-free survival (PFS). Between September 25, 2012, and November 11, 2015, we enrolled 47 evaluable patients. Forty-five (96%) patients completed the protocol treatment. There were no deviations or violations in the DA-EPOCH-R dose levels. The complete response rate was 91%, and the overall response rate was 94%. At a median follow up of 3.1 years (range, 2.0-4.9 years), the 2- year PFS was 79% [95% confidence interval (CI): 64-88]. The 2-year overall survival was 89% (95%CI: 76-95). Toxicity included grade 4 neutropenia in 46 (98%) patients, grade 4 thrombocytopenia 12 (26%) patients, and febrile neutropenia in 31 (66%) patients. No treatment-related death was noted during the study. DA-EPOCH-R/HD-MTX might be a first-line therapy option for stage II-IV CD5+ DLBCL and warrants further investigation. (Trial registered at: UMIN-CTR: UMIN000008507.).

Optimal treatment strategy with nilotinib for patients with newly diagnosed chronic-phase chronic myeloid leukemia based on early achievement of deep molecular response (MR4.5 ): The phase 2, multicenter N-Road study.

For patients who have chronic myeloid leukemia (CML), one of the primary treatment options is administration of nilotinib 300 mg twice daily (BID). In previous studies which compared outcomes associated with nilotinib or imatinib treatment, nilotinib achieved a higher rate of deep molecular response (MR). We conducted a phase II, open-label, multicenter study to investigate an intrapatient nilotinib dose-escalation strategy for patients with newly diagnosed chronic-phase (CP) CML based on early MR4.5 achievement. The primary study endpoint was achievement of MR4.5 by 24 months following the initiation of nilotinib 300 mg BID. Fifty-three patients were enrolled, 51 received nilotinib, and 37 completed the treatment. An increase in the nilotinib dose (to 400 mg BID) was allowed when patients satisfied our criteria for no optimal response at any time point. The median (range) dose intensity was 600 (207-736) mg/day. Of 46 evaluable patients, 18 achieved an optimal response and 28 did not. Of the latter, nine patients underwent dose escalation to 400 mg BID, and none achieved MR4.5 . The remaining 19 patients could not undergo dose escalation, 12 (63%) because of adverse events (AEs), and 7 (37%) for non-AE related reasons. Four of these patients achieved MR4.5 . The MR4.5 rate by 24 months was 45.7%. The progression-free, overall and event-free survival were each 97.6%. No new safety concerns were observed. Our findings support the use of continuous nilotinib at a dose of 300 mg BID for newly diagnosed patients with CML-CP.

Treatment-free remission after first-line dasatinib treatment in patients with chronic myeloid leukemia in the chronic phase: the D-NewS Study of the Kanto CML Study Group.

Treatment outcomes for chronic myeloid leukemia (CML) have dramatically improved with the development of tyrosine kinase inhibitors (TKI). However, due to the improved prognosis for CML, problems have arisen from long-term administration of TKI. The present study sought to verify whether more patients could achieve treatment-free remission (TFR) after stopping the administration of dasatinib using dasatinib as frontline treatment. Treatment-naïve chronic phase CML cases were treated with dasatinib as frontline treatment. Dasatinib treatment was stopped for 26 patients who achieved deep molecular response (DMR) within 24 months and were able to maintain DMR for an additional 2 years. Ten patients (38.5%) achieved DMR maintenance after 12 months. Recurrence was confirmed in 16 patients, and the median recurrence-free survival time was 5.1 months. The cumulative DMR rates at six and 12 months after restarting treatment were 84.6% and 100%, respectively. The results of this study demonstrated that the DMR maintenance rate after 12 months was 38.5%, which was not significantly different from previous TKI stop trials. The 2-year dasatinib administration period after reaching DMR did not contribute to improve TFR rates. These results suggest that the type of TKI is not associated with better TFR rates.

Prophylactic Antiemetics for Haematological Malignancies: Prospective Nationwide Survey Subset Analysis in Japan.

BACKGROUND/AIM: Although neurokinin-1 receptor antagonists are approved chemotherapy drugs in Japan, no nationwide surveys have been performed to validate chemotherapy-induced nausea and vomiting (CINV) guidelines in clinical practice. This study evaluated CINV in patients with haematological malignancies starting first-time chemotherapy. PATIENTS AND METHODS: A nationwide CINV survey on patients with haematological malignancies was conducted at 118 institutions. Patients undergoing moderately emetic chemotherapy (n=17) and highly emetic chemotherapy (HEC; n=180) were compared. RESULTS: Forty-one patients undergoing HEC received triple antiemetics. Female gender and young age were risk factors for early-phase nausea, while female gender remained a risk factor for late-phase nausea and vomiting. Among 125 patients receiving CHOP (doxorubicin, cyclophosphamide, vincristine, prednisone)-like regimens, complete response and complete control were increased in patients receiving triple antiemetics, compared to those with double antiemetics. CONCLUSION: Guideline compliance was very low. Although not statistically significant, there was a trend for reduced CINV and improved disease control for triple versus double antiemetics, suggesting that triple antiemetics should be considered for HEC, especially in young female patients with non-Hodgkin lymphoma receiving CHOP-like regimens.

Correction to: Plerixafor for mobilization and collection of haematopoietic stem cells for autologous transplantation in Japanese patients with non-Hodgkin lymphoma: a randomized phase 2 study.

The affiliation of the last author, Kenshi Suzuki has been incorrectly published in the original publication of the article. The correct affiliation is provided in this correction.

Plerixafor for mobilization and collection of haematopoietic stem cells for autologous transplantation in Japanese patients with non-Hodgkin lymphoma: a randomized phase 2 study.

The present study (ClinicalTrials.gov Identifier: NCT02221492) was conducted to assess the efficacy and safety of plerixafor for the mobilization and collection of haematopoietic stem cells (HSCs) for autologous transplantation in Japanese non-Hodgkin lymphoma (NHL) patients. In this randomized phase 2 study, patients received granulocyte-colony stimulating factor (G-CSF, filgrastim) 400 µg/m²/day for up to 8 days. Starting on the evening of day 4, patients received, for up to 4 days, either plerixafor (240 µg/kg/day) in the G-CSF+ plerixafor arm (GP arm) or G-CSF alone arm (G arm). On day 5, daily apheresis started and was continued for up to 4 days, or until ≥ 5 × 106 CD34+ cells/kg was collected. A total of 32 patients were randomized to either the GP or G arm. In the GP arm, 9/16 patients (56.3%) achieved collection of ≥ 5 × 106 CD34+ cells/kg in ≤ 4 days of apheresis, while 1/16 patient (6.3%) achieved this target in the G arm. The most common treatment-emergent adverse events in the GP arm were back pain (56.3%), platelet count decreased (25.0%), headache, diarrhoea, and nausea (18.8% each). We found that plerixafor was well tolerated and effective for the mobilization and collection of peripheral HSCs for autologous transplantation in Japanese NHL patients.

Regulatory T cell inhibition by dasatinib is associated with natural killer cell differentiation and a favorable molecular response-The final results of the D-first study.

We evaluated the effects of regulatory T cell (Treg) inhibition during dasatinib treatment on the anticancer immune response, particularly on natural killer (NK) cells and cytotoxic T lymphocytes (CTLs). Fifty-two newly diagnosed Japanese patients with chronic myeloid leukemia (CML) in the chronic phase were enrolled in the D-first study; all received 100 mg of dasatinib once daily and were followed for at least 36 months. The cumulative deep molecular response (DMR, MR4) rate was 65% by 36 months; the 3-year overall survival was 96%. CD4+ T cell counts were stable, whereas the proportion of CD4+CD25+CD127low (Treg) cells decreased in a time-dependent manner. The DMR rate by18 months was significantly better in low Treg patients (<5.7% at 12 months) compared to the remaining patients (odds ratio 4.07). NK cell and CTL counts at several time points were inversely correlated with Treg counts. Furthermore, the degree of NK cell differentiation (CD3-CD57+/CD3-CD56+) was closely and inversely correlated with the proportion of Treg cells throughout the observation period, and showed a gradually increasing trend. In conclusion, our results demonstrate that Treg inhibition by dasatinib contributes to better treatment response through enhancement of the immune system, particularly via NK cell differentiation.

Randomized phase II study of a bendamustine monotherapy schedule for relapsed or refractory low-grade B-cell non-Hodgkin lymphoma or mantle cell lymphoma (RABBIT-14).

The aim of this randomized phase II study was to improve the treatment delays and discontinuations associated with bendamustine use by comparing the effect of Benda-14 (intravenous bendamustine, 120 mg/m2 on days 1 and 15, repeated every 4 weeks for a total of 6 cycles) with those of the standard treatment in relapsed indolent lymphoma and/or mantle cell lymphoma. Forty-six patients were randomly assigned to the treatments from September 2012 to February 2016. Treatment accomplishment rate and median relative dose intensity were similar in both arms: 38 and 63.4% in the Benda-14 arm and 41 and 66.3% in the standard treatment arm, respectively. The overall response rate and median progression-free survival, respectively, were 83% and 21.0 months for Benda-14, and 77% and 15.5 months for the standard treatment. Benda-14 induced favorable responses with less frequent hematological toxicities.

Japanese phase II study of rituximab maintenance for untreated indolent B-cell non-Hodgkin lymphoma with high tumor burden.

Recent large-scale randomized clinical trials in Europe and the US demonstrated that maintenance therapy with rituximab significantly improved the progression-free survival (PFS) in indolent B-cell non-Hodgkin lymphoma (B-NHL) patients, especially those with follicular lymphoma (FL). However, rituximab maintenance has not been approved in Japan, because there are no clinical data supporting the benefit of rituximab maintenance in Japanese patients. Therefore, we conducted a single-arm, multicenter bridging study in previously untreated indolent B-NHL patients with high tumor burden. The primary endpoint was 4-year PFS and was expected to be 70 % based on previous studies. Sixty-two patients, including 55 FL patients, were enrolled and received induction therapy with CHOP combined with rituximab (R-CHOP). Fifty-eight patients responding to R-CHOP induction received rituximab at 375 mg/m2 every 8 weeks for 2 years as for the rituximab maintenance arm in the PRIMA study. A 4-year PFS of 69.8 % was obtained (95 % confidence interval 55.9-80.0 %). Rituximab maintenance was well tolerated and common adverse events were infections, neutropenia, and/or leukopenia that were manageable with conventional supportive care. No patients died. These data were compatible with the PRIMA data. R-CHOP induction followed by rituximab is useful in Japanese patients with untreated indolent B-NHL having high tumor burden. Clinical trial number UMIN000001191.

Association of pleural effusion with an early molecular response in patients with newly diagnosed chronic-phase chronic myeloid leukemia receiving dasatinib: Results of a D-First study.

Despite the efficacy and safety of dasatinib treatment for chronic-phase chronic myeloid leukemia (CML-CP), adverse effects such as pleural effusion (PE) are still a serious concern. We determined the clinical significance of PE incidence using patient data derived from the D-First clinical study. In the present study, chest radiography and quantification of specific lymphocyte subsets were performed routinely after initiation of dasatinib treatment. Among 52 patients with newly diagnosed CML-CP, 17 (33%) developed PE within 18 months after initial dasatinib administration, but all cases were moderate (Grade 1, 10 patients; Grade 2, 7 patients). CD56+ lymphocyte counts at 1 month correlated significantly with the incidence of PE, whereas lymphocytosis did not. The major molecular response (MMR) rate at 3 months (although not at later times) was significantly higher in PE-positive patients than PE-negative patients (59% versus 24%, respectively; P=0.013). Deep molecular response rates did not differ significantly between the PE groups at any time point during the observation period. Our results suggest that an immune-mediated mechanism involving natural killer cells underlies the development of PE in patients receiving dasatinib for 18 months. This mechanism likely promotes transient tumor regression in patients newly diagnosed with CML-CP.

Early cytotoxic lymphocyte expansion contributes to a deep molecular response to dasatinib in patients with newly diagnosed chronic myeloid leukemia in the chronic phase: results of the D-first study.

Dasatinib is one of the key treatment options for chronic myeloid leukemia (CML) patients. Increase in lymphocyte counts has been known to be predictive of a good treatment response under dasatinib treatment as a second line therapy. However, clinical significance of lymphocyte dynamics in the upfront setting has yet to be clarified. To investigate the significance of lymphocyte dynamics in newly diagnosed chronic phase (CP)-CML, patient data of D-First study (ClinicalTrials.gov NCT01464411) were analyzed. Fifty-two CML-CP patients enrolled to this study were treated with dasatinib (100 mg day(-1) ) and all were followed-up for 18 months. The incidence of lymphocyosis was observed in 14 (27%), but it was not associated with deep molecular response achievement. However, natural killer (NK) cell or cytotoxic T lymphocyte (CTL) counts at 1 month were significantly higher in patients with deep molecular response (DMR) by 18 months compared to those without DMR. When the patients were divided into two groups according to those calculated thresholds by receiver operating characteristic curve (407/µL for NK cells and 347/µL for CTLs), the cumulative DMR rates by 18 months were significantly better in higher value group compared to lower value group. In contrast, regulatory T cell counts were significantly lower at 12 and 15 months in patients achieved DMR. These results suggest the presence of dual effects of dasatinib on immune system through the cytotoxic lymphocytes activation and Treg deregulation in different periods in newly diagnosed CML-CP.

Shorter halving time of BCR-ABL1 transcripts is a novel predictor for achievement of molecular responses in newly diagnosed chronic-phase chronic myeloid leukemia treated with dasatinib: Results of the D-first study of Kanto CML study group.

To investigate the factors that affect molecular responses on dasatinib treatment in patients with chronic-phase chronic myeloid leukemia (CML-CP), we performed a clinical trial named the "D-First study." Fifty-two patients with newly diagnosed CML-CP were enrolled in this study and received 100 mg dasatinib once daily. A deep molecular response (DMR) was defined as <50 copies/µg RNA of BCR-ABL1 transcript value corrected by GAPDH, which ensures <0.01% of BCR-ABL1 transcript value according to International Scale (BCR-ABL1(IS)). The halving time for BCR-ABL1 transcripts was calculated using transcript levels before dasatinib treatment, transcript levels after 3 months of treatment, and the treatment time between these two points. In terms of molecular response, 38 of 51 (75%) patients reached major molecular response (MMR) by 12 months, and the rate of DMR by 18 months was 59% (30/51). While both BCR-ABL1 transcript levels before treatment and a shorter halving time of BCR-ABL1 transcripts (≤14 days) were significant factors affecting achievement of MMR by 12 months, the Sokal score at diagnosis was not associated with MMR. Importantly, the halving time was the only factor that predicted achievement of DMR by 18 months. We showed that patients with CML-CP treated with dasatinib can be stratified according to the early treatment response as determined by the halving time of BCR-ABL1 transcripts. These data emphasize the significance of the early response from dasatinib treatment in achieving a DMR. (ClinicalTrials.gov; NCT01464411).

[Diffuse large B-cell lymphoma of the testis relapsed 16 years after achieving complete response].

Testicular lymphoma is a rare disease, accounting for 1-2% of non-Hodgkin lymphoma and 5-9% of all testicular tumors, and has a high relapse rate with a poor prognosis. We report a patient with testicular diffuse large B-cell lymphoma (DLBCL) who relapsed after being in remission for 16 years. He had undergone orchiectomy of the right testis and was diagnosed as having DLBCL (stage IAE) at 49 years of age. After 3 cycles of CHOP, he achieved a complete remission. Orchiectomy was performed because of a left testicular tumor, and he was again diagnosed with DLBCL at the age of 65. VH3-21 was detected in lymphoma cells at the times of both the first diagnosis and the relapse based on analysis of the variable region of the immunoglobulin heavy chain. Accordingly, the lymphoma cells at relapse were confirmed to be the same clone as that which had been documented at the first diagnosis.

Prognostic significance of pleural or pericardial effusion and the implication of optimal treatment in primary mediastinal large B-cell lymphoma: a multicenter retrospective study in Japan.

The prognosis of patients with primary mediastinal large B-cell lymphoma has improved over recent years. However, the optimal treatment strategy including the role of radiotherapy remains unknown. We retrospectively analyzed the clinical outcomes of 345 patients with newly diagnosed primary mediastinal large B-cell lymphoma in Japan. With a median follow up of 48 months, the overall survival at four years for patients treated with R-CHOP (n=187), CHOP (n=44), DA-EPOCH-R (n=9), 2(nd)- or 3(rd)-generation regimens, and chemotherapy followed by autologous stem cell transplantation were 90%, 67%, 100%, 91% and 92%, respectively. Focusing on patients treated with R-CHOP, a higher International Prognostic Index score and the presence of pleural or pericardial effusion were identified as adverse prognostic factors for overall survival in patients treated with R-CHOP without consolidative radiotherapy (IPI: hazard ratio 4.23, 95% confidence interval 1.48-12.13, P=0.007; effusion: hazard ratio 4.93, 95% confidence interval 1.37-17.69, P=0.015). Combined with the International Prognostic Index score and the presence of pleural or pericardial effusion for the stratification of patients treated with R-CHOP without radiotherapy, patients with lower International Prognostic Index score and the absence of effusion comprised approximately one-half of these patients and could be identified as curable patients (95% overall survival at 4 years). The DA-EPOCH-R regimen might overcome the effect of these adverse prognostic factors. Our simple indicators of International Prognostic Index score and the presence of pleural or pericardial effusion could stratify patients with primary mediastinal large B-cell lymphoma and help guide selection of treatment.

Rituximab monotherapy with eight weekly infusions for relapsed or refractory patients with indolent B cell non-Hodgkin lymphoma mostly pretreated with rituximab: a multicenter phase II study.

Information regarding rituximab monotherapy with eight weekly infusions for relapsed or refractory indolent B cell non-Hodgkin lymphoma (B-NHL), in particular for patients pretreated with rituximab, is limited. To evaluate the efficacy and safety of eight doses of rituximab monotherapy, 52 patients with relapsed or refractory indolent B-NHL were enrolled in the present study. Forty of 45 eligible patients (89%) had follicular lymphoma and 24 (53%) were at intermediate or high risk group according to the Follicular Lymphoma International Prognostic Index. The median number of prior chemotherapy regimens was 1 (range 1-7). At the median follow-up of 12.2 months, the overall response rate (ORR), complete response rate (%CR), and median progression-free survival (PFS) were 69% (95% confidence interval [CI] 53%-82%), 47% (95% CI 32%-62%), and 15.6 months (95% CI 10.6- months), respectively. In the 33 patients pretreated with rituximab, the ORR, %CR, and median PFS were inferior compared with values for the 12 patients who had not received rituximab previously (64%vs 83% for ORR; 39%vs 67% for %CR; and 13.8 vs 17.5 months for median PFS, respectively). All mild-to-moderate infusion-related toxicities were reversible. Grade 3/4 non-hematologic adverse events occurred in six of the 52 patients. Two patients developed Grade 4 late-onset neutropenia and a decrease (>50%) in serum immunoglobulin was observed in six patients. In conclusion, rituximab monotherapy with eight weekly infusions is effective in relapsed patients with indolent B-NHL, with acceptable toxicities, including in patients pretreated with rituximab; however, careful monitoring is recommended for infections associated with late-onset neutropenia and hypogammaglobulinemia. (University Hospital Medical Information Network no. UMIN000002974.)