Advanced Stage Follicular Lymphoma Patients Research Articles

P1132: PET INTERIM RESULTS PREDICT PROGRESSION-FREE-SURVIVAL IN FOLLICULAR LYMPHOMA PATIENTS WITH ADVANCED STAGE

Background: Follicular lymphoma (FL) is the second most common NHL. It is generally associated with an indolent course, but a subgroup of patients has worse outcome, lower progression-free-survival (PFS) and higher risk of histological transformation (HT). Since Lugano classification, the Deauville criteria using the 5-point scale (D5PS) is validated as the interpretation method for response assessment PET scans in HL and NHL. Nevertheless, the prognostic value of D5PS in the interim evaluation in FL (PETINT) is not well stablished. Additionally, the quantitative value of SUVmax parameter in the response assessment is almost not studied. Aims: The aim of this study is to evaluate the prognostic value of PETINT evaluation and quantitative mid-induction SUVmax parameter in a cohort of FL patients followed and treated in a single, academic centre with chemo-immunotherapy. Methods: 179 consecutive FL patients were newly diagnosed between 2011 and 2020. 40 patients that did not require systemic treatment and 68 that did not have a PETINT evaluation were excluded. As well, patients with HT (9) and FL grade 3B (4) were excluded. From the 58 remaining patients, clinical, laboratory and PET examinations data was recorded. All patients were Ann-Arbor stage III-IV and were treated with chemo-immunotherapy. PET/CT examinations were acquired at baseline, mid-induction (after 4 cycles of treatment) and end of treatment (EOT). PET positive was considered when Deauville score (DS) was 4 or 5. Statistical analysis was performed with SPSS® using Cox regression, Kaplan-Meier survival curves and log-rank test. Results: The median age at diagnosis was 64 years (26-95) and 29 (50%) patients were female. 33/58 (57%) patients had a high risk FLIPI and 18/55 (33%) had a high risk PRIMA-PI. 37 (64%) patients were treated with R-CHOP and 21 with R-bendamustine. 44 (76%) patients received maintenance with rituximab. After a median follow-up of 43 months, 20 (34%) patients had progression. On PETINT, 19 (32%) patients were PET(+), and 10 of them remained PETEOT(+). Only one patient with PETINT(-), became PETEOT(+). PETINT(+) patients had a median PFS of 31 months compared with a median PFS of 88 months in PETINT(-) (p < 0.001), Figure 1. 38.2% PETINT(+) presented progression of disease in less than 24 months (POD24) vs 5.2% on those who were in PETINT(-), with a p<0.001. PETINT(-) presented a negative predictive value of 95%. No differences in OS was observed. 3/19 (16%) patients with PETINT(+) presented HT vs 1/39 (2%) with PETINT(-). Transformation-free survival was lower in patients with PETINT(+), with a trend towards significance (p= 0.057). Similar PFS results were obtained independently of prognostic index, treatment or maintenance received. Analysing the prognostic value of quantitative SUVmax, patients with SUVmax< 3,8 (28/58; 48%) presented better outcomes, with larger PFS (p < 0.001) and less HT (p= 0.004). Figure 2. Additionally, PET/CT findings at EOT were predictive of relapse, with a median PFS of 30 months in PETEOF (+) vs 88 months in PETEOT(-) (p = 0.005). PETEOT (+) presented a higher risk of HT (p= 0.004). Figure 3. Image:Summary/Conclusion: This study suggests that response assessment by PET at mid-induction is predictive of relapse in advanced stage FL patients treated with 1st line chemo-immunotherapy. With previous conflicting results, further studies are needed to confirm this preliminary data. Probably, new laboratory tests such as MRD monitored by liquid biopsy could improve the detection of this subgroup of high risk patients and help to develop a response-adapted precision therapy.

Impact of Immunochemotherapy with R-Bendamustine or R-CHOP in the Post-Induction Management of Treatment Naïve Advanced Stage Follicular Lymphoma Patients: A Subset Analysis of the FOLL12 Trial By the Fondazione Italiana Linfomi (FIL)

Impact of Immunochemotherapy with R-Bendamustine or R-CHOP in the Post-Induction Management of Treatment Naïve Advanced Stage Follicular Lymphoma Patients: A Subset Analysis of the FOLL12 Trial By the Fondazione Italiana Linfomi (FIL)

Clinical Factors Impact on Pharmacokinetics of CT-P10 and Reference Rituximab in Patients with Advanced-Stage Follicular Lymphoma

Background: CT-P10 is the first biosimilar to the innovator rituximab (RTX), which was approved by the European Medicines Agency for all indications for which RTX is approved. Pharmacokinetic equivalence and comparable efficacy was demonstrated in advanced-stage follicular lymphoma patients (Kim WS et al. Lancet Haematol. 2017; S2352-3026(17)) as well as in rheumatoid arthritis (Yoo DH, et al. Arthritis Rheumatol. 2016; 68 (suppl 10)). It is known that there are several factors affecting on pharmacokinetics (PK) of rituximab. However, there are limited data on comparing PK data between a biosimilar of rituximab and RTX with different subgroups in advanced-stage follicular lymphoma (AFL) patients.Objective: This report is to investigate the PK of CT-P10 according to the several relevant clinical factors and to compare with RTX in the post-hoc analysis of randomized controlled trial to compare CT-P10 and RTX in advanced-stage follicular lymphoma (NCT02162771).Methods: A total of 121 patients of PK population were included in this analysis. Fifty nine patients in the CT-P10 group and 62 patients in the RTX group received CT-P10 or RTX (375 mg/m2 i.v) plus CVP (cyclophosphamide, vincristine and prednisone) for every 3 weeks over 8 cycles. Area Under the Concentration-time curve at steady state (AUCtau) and the maximum serum concentration at steady state (CmaxSS) at Cycle 4 and trough serum concentration (Ctrough) at Cycle 4 and Cycle 8 were calculated by standard non-compartmental methods using Phoenix WinNonlin. The parameters were analysed by subgroups of Gender (male vs. female), Eastern Cooperative Oncology Group (ECOG) Performance Status (0 vs. ≥1), Follicular Lymphoma International Prognostic Index (FLIPI) Score (0-2 vs. 3-5) and its component (Age (≥60 vs. <60), Hemoglobin [Hb] (≥120g/L vs. <120g/L), Lactate dehydrogenase [LDH] (>UNL vs. ≤UNL), number of nodal sites (>4 vs. ≤4)), presence of bulky lesion at baseline (≥7cm vs. <7cm) and Complete response (CR)/Complete response unconfirmed (CRu) as best overall response assessed by International Working Group 1999 in the each and combined group of CT-P10 and RTX. Outliers which determined by robust regression outlier testing were excluded in this analysis. For AUCtau, 7 patients (5 in the CT-P10 group and 2 in the RTX group) and among them, 4 patients (2 patients in each group) for CmaxSS were defined as outliers.Result: Higher AUCtau and CmaxSS were observed in patients who are female, under 60 years old, good ECOG Performance Status, low FLIPI score, normal Hb and LDH levels, and non-bulky disease at baseline as shown in Table 1. In patients who achieved CR/CRu as their best overall response during 8 cycles showed higher AUCtau, CmaxSS and Ctrough than in patients who did not achieve CR/CRu response in both CT-P10 and RTX groups. At Cycle 4 and Cycle 8, mean Ctrough in the CR/CRu responder were 72 μg/mL, 108 μg/mL, respectively, and those concentrations are 56 μg/mL, 96 μg/mL in the CR/CRu non-responder. Importantly, there was no statistically significant difference between the CT-P10 and RTX in any of subgroup analyses; confidence interval of the ratio of geometric mean of CT-P10 to RTX contains 1 using Satterthwaite approximation for each comparison.Conclusion: Female gender, younger age (<60), better ECOG Performance Status, lower FLIPI score, LDH and Hb levels in normal range, absence of bulky disease at baseline and better response are factors associated with increased serum rituximab concentration in the combined treatment groups. No statistically significant differences were found between CT-P10 and RTX groups in PK at all subgroup analyses. Therefore, this result shows that the PK of CT-P10 is in accordance with the RTX from historical data and further supports the PK similarity between CT-P10 and RTX. [Display omitted] DisclosuresKim:Celltrion, Inc: Consultancy, Honoraria; Roche: Research Funding; Mundipharma: Research Funding; Novartis: Research Funding; Kyowa-Kirin: Research Funding; Donga: Research Funding; J&J: Research Funding; Takeda: Research Funding. Coiffier:Celltrion, Inc: Consultancy, Honoraria. Buske:Hexal: Honoraria; Celltrion, Inc.: Consultancy, Honoraria; Pfizer: Honoraria; Gilead: Honoraria; Janssen: Honoraria, Research Funding; Roche: Honoraria, Research Funding. Ogura:SymBio: Consultancy, Research Funding; Celgene: Consultancy, Honoraria; Astrazeneca: Honoraria; Takeda: Consultancy, Honoraria; Mundipharma: Consultancy; MeijiSeika Pharma: Consultancy; Celltrion, Inc: Consultancy, Honoraria. Kwak:Celltrion, Inc: Consultancy; InnoLifes: Consultancy, Equity Ownership; Pepromene Bio: Consultancy, Equity Ownership. Lee:Celltrion, Inc: Employment. Bae:Celltrion, Inc: Employment. Kim:Celltrion, Inc: Employment. Kim:Celltrion, Inc: Employment. Lee:Celltrion, Inc: Employment. Kwak:Celltrion, Inc: Employment. Lee:Celltrion, Inc: Employment.

Neoantigens Are Typically Associated with Intact HLA Class I Presentation in Early-Stage Follicular Lymphoma

Neoantigens Are Typically Associated with Intact HLA Class I Presentation in Early-Stage Follicular Lymphoma

Renewed interest for low‐dose radiation therapy in follicular lymphomas: From biology to clinical applications

Follicular lymphoma (FL) is the most common subtype of indolent non-Hodgkin lymphoproliferative disorders. Treatment strategies for FL may include several therapeutic choices, ranging from a "watchful waiting" approach to stem cell transplantation, mostly depending on staging, age, risk factors, and disease burden at diagnosis. The high radiosensitivity of FL compared with other solid tumors has been known since the beginning of radiotherapy treatment in lymphoma patients. Doses of 24 to 40Gy were considered appropriate in first line curative treatment for localized disease (stages I-II), but several publications investigating low-dose radiotherapy (LDRT) of 4Gy (2×2Gy) reported an overall response rate surprisingly high. Due to its high local efficacy and negligible toxicity, LDRT might be offered to both early and advanced stage FL patients in combination with new agents, at diagnosis or after several lines of systemic therapy. The aim of this review is to summarize and discuss the current knowledge on LDRT for FL and its potential application in a curative setting in combination with new drugs for both early and advanced disease.

Management strategy for follicular lymphoma.

Follicular lymphoma (FL) is incurable with the current standard therapeutic strategy, although the natural history of FL has improved in the last few decades. Treatment strategy for FL is considered by stage and tumor burden. For advanced-stage FL patients with low tumor burden, monitoring remains an appropriate approach. Single agent rituximab is also suggested as a good alternative. The addition of rituximab to chemotherapy has improved overall survival in advanced-stage FL patients with high tumor burden. The optimal chemotherapy to partner with rituximab might be CHOP or bendamustine. Rituximab maintenance after successful induction rituximab-based chemotherapy prolongs PFS. Recently, progression within 24 months of first-line chemotherapy has been established as a predictor of inferior outcome, with a 50% risk of death in 5 years. Addressing this high-risk group is important for optimal future treatment strategies.

Rituximab Maintenance for Advanced Follicular Lymphoma (FL) Patients - Comparison of Outcomes after First and Second Line Treatment in a Single Center Series

Standard approach to advanced stage FL patients in need of treatment is immunochemotherapy followed by rituximab maintenance (RM). Maintenance improves disease control after first line and overall survival in the relapse setting. The relative benefits of maintenance after first or subsequent treatment have not been directly compared.Purpose: To compare the clinical outcome of patients receiving RM after first-line treatment with those who received RM for the first time after second line.Patients and Methods: We retrospectively analyzed the outcomes (time to next treatment, TTNT, and progression free survival, PFS) of a single center series of advanced FL patients in remission after first or second treatment who received RM. Demographic and clinical characteristics before first or second induction (age, gender, FLIPI and FLIPI2) as well as induction chemotherapy, response rate, PFS and TTNT were retrieved from clinical charts. Patient characteristics at the beginning of induction were compared by Chi-squared test and time-to-event outcomes evaluated by the Kaplan Meyer method and compared by log rank test, with and without stratification for FLIPI; we calculated the adjusted hazard ratio controlled for FLIPI using Cox regression; p‹0.05 was considered significant.Results: Among 371 advanced FL patients diagnosed and treated in a single center between 2001 and 2013, we identified 83 (45% male) who responded to first or second induction and received RM between 2005 and 2015 (59 after first line - M1 group - and 24 after second line - M2 group; 375 mg/m2 every 2 or 3 months for 2 years, respectively). M2 patients were older than M1 (median age 63 versus 55 yo). Other characteristics before induction were similar between the two groups, including FLIPI (low 14% and 13%, intermediate 42% and 33%, high 42% and 42% for M1 and M2, respectively; p=0.93) and FLIPI2 risk group distribution (low 10% and 4% , intermediate 49% and 38%, high 36% and 38% for M1 and M2, respectively; p=0.62). Median time from diagnosis was 5.1 years in M2 patients; M1 patients were treated at a median of 1.9 months after diagnosis.First line treatment in the M1 group was mostly RCHOP (76%) while similar proportions of M2 pts received RCHOP (38%) and RCVP (46%) as second line. 20/24 of M2 pts (83%) had received Rituximab as part of first line treatment. CR/CRu rates after induction were comparable (48% and 42% in M1 and M2 pts respectively; p=0.17). After maintenance, with 13 pts not yet evaluable for response, ORR was 68% in M1 and 50% in M2 (p= 0.15). The frequency of CR/CRu was similar for first and second line patients (43% and 42% in M1 and M2, respectively) with 10/31 (32%) and 4/11 (36%) PR patients converting to CR after M1 and M2, respectively. At a median follow-up of 2.3 in M1 and 2.5 years in M2, relapse/progression occurred in 16 (27%) and 8 (33%) patients, respectively. A new treatment was started in 19% and 29% of patients in the M1 and M2 groups. Accordingly, TTNT after M1 (not reached) was significantly longer than after M2 (33.2 months), p=0.04. This difference was not significant in stratified analysis by FLIPI. However, when controlling for FLIPI, the hazard of subsequent therapy in M2 was twice as M1 (HR=2.1; 95% CI: 0.8-5.4). Two-year PFS was also superior in M1 (80% [95% CI 70-92%] versus 62% [95% CI 44-87%] in M2) although not statistically significant (p= 0.19). Indeed, there was a 50% increase in the risk of progression or death adjusted for FLIPI in M2 compared to M1 (HR=1.5; 95%CI: 0.6-3.8).Conclusion: In this series, although patients receiving RM both after first and second induction therapy benefited from the treatment, longer treatment-free intervals and disease control were seen in the first line setting. The benefits of repeating Rituximab maintenance have not been prospectively evaluated; in countries where economic constraints impose restrictions to its repeated use, our results suggest that advanced FL patients should preferentially receive RM after first line. DisclosuresSilva:Roche Pharmaceutics: Consultancy.

Pharmacokinetic and Safety of CT-P10, a Biosimilar Candidate to the Rituximab Reference Product, in Patients with Newly Diagnosed Advanced Stage Follicular Lymphoma (AFL)

Background: CT-P10 is a biosimilar candidate to the reference rituximab product, EU-approved MabThera® and US-licensed Rituxan®. CT-P10 has an identical amino acid sequence and highly similar physicochemical and in vitro functional properties to its reference drug. In patients with rheumatoid arthritis, CT-P10 has demonstrated compelling similarity in pharmacokinetics (PK), pharmacodynamics (PD), efficacy, safety and immunogenicity (Yoo DH, et al. Arthritis Rheum. 2013;65(10):1736).Objective: The goal of this study was to demonstrate PK similarity of CT-P10 to rituximab, each administered in combination with cyclophosphamide, vincristine, and prednisone (CVP) in patients with newly diagnosed Advanced Follicular Lymphoma (AFL) (NCT02162771) (Kim WS et al. Blood. 2015;126(23): 5111). The results of PK, PD, safety and immunogenicity up to Core Cycle 4 (12 weeks) are presented here from this ongoing study.Methods: Patients with AFL were randomized 1:1 to receive infusion (375mg/m2) of either CT-P10 or rituximab, at a 3-week interval, in combination with CVP. PK analysis was conducted in terms of AUCtau and Cmax at steady state, Core Cycle 4, as primary PK endpoints. PK parameter values considered as outliers determined by robust regression outlier testing were excluded from the pharmacokinetic primary analysis.Results: In total, 121 patients were randomly assigned to receive either CT-P10 (n=59) or rituximab (n=62) in combination with CVP. Result of CT-P10 PK at Core Cycle 4 was similar to that of rituximab. The ratios (90% CI) of geometric least square means (CT-P10 to rituximab treatment group) were 102.3% (94.1%-111.2%) for AUCtau and 100.7% (93.8%-108.0%) for CmaxSS at Core Cycle 4. The 90% CIs of ratio of geometric LS means for both AUCtau and CmaxSS were entirely contained within the equivalence margin of 80% to 125% (Table 1 and Figure 1). Mean serum concentrations of the study drug were highly similar for the 2 treatment groups at each time point (Core Cycle 1 to 4).The B-cell kinetics was similar up to Core Cycle 4 in the 2 treatment groups. Median number of B-cells decreased to below the lower limit of quantification (LLoQ) (20 cells/μL) 1 hour after the end of infusion at Core Cycle 1 and remained below the LLoQ at each subsequent cycle, up to and including Core Cycle 4.The proportion of patients with a positive anti-drug antibody up to Core Cycle 4 at post-treatment visits was similar between the 2 treatment groups; 3/59 (5.1%) patients and 2/62 (3.2%) patients in the CT-P10 and rituximab groups, respectively.In addition, CT-P10 was well tolerated and the safety profile of CT-P10 up to Core Cycle 4 was similar to that of rituximab. The number of patients who experienced at least 1 treatment emergent adverse event (TEAE) was 43 (72.9%) patients and 41 (66.1%) patients in CT-P10 and rituximab treatment groups, respectively. The proportion of patients who experienced at least 1 treatment emergent serious adverse event considered by the investigator to be related to the study treatment was similar between the 2 treatment groups; 2/59 (3.4%) patients and 2/62 (3.2%) patients in the CT-P10 and rituximab groups, respectively. The frequencies of adverse events special interest (AESI) were similar between the 2 treatment groups (Table 2).Conclusion: This study demonstrated similarity of PK in terms of AUCtau and CmaxSS between CT-P10 and rituximab in AFL patients. The B-cell kinetics and immunogenicity were comparable between the two treatment groups. CT-P10 was well tolerated with a safety profile comparable to that of rituximab up to and including Core Cycle 4 (12 weeks). [Display omitted] [Display omitted] [Display omitted] DisclosuresCoiffier:Celltrion, Inc.: Consultancy, Honoraria. Sancho:Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celltrion, Inc: Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Jurczak:Celltrion, Inc: Research Funding; Gilead Sciences: Research Funding; Acerta: Research Funding; Bayer: Research Funding; Janssen: Research Funding. Kim:Celltrion, Inc.: Research Funding. Nagarkar:Celltrion, Inc.: Research Funding. Zhavrid:Celltrion, Inc.: Research Funding. Hernandez Rivas:Celltrion, Inc.: Research Funding. Prokharau:Celltrion, Inc.: Research Funding. Zodelava:Celltrion, Inc.: Research Funding. Osmanov:Celltrion, Inc.: Research Funding. Ogura:SymBio Pharmaceuticals: Consultancy, Honoraria; Celltrion, Inc.: Consultancy, Honoraria. Buske:Celltrion, Inc.: Consultancy, Honoraria. Kwak:Celltrion, Inc.: Consultancy. Kim:Celltrion, Inc.: Consultancy, Honoraria.

Global Phase I/III Pharmacokinetic and Efficacy Study Comparing CT-P10, a Biosimilar Candidate to the Rituximab Reference Product in Patients with Advanced Stage Follicular Lymphoma (AFL)

Global phase I/III pharmacokinetic and efficacy study comparing CT-P10, a biosimilar candidate to the rituximab reference product in patients with advanced stage follicular lymphoma (AFL)CT-P10 is a biosimilar candidate to the reference rituximab product, EU-approved MabThera® and US-licensed Rituxan®. CT-P10 has an identical amino acid sequence and highly similar physicochemical and in vitro functional properties to its reference drug. In patients with rheumatoid arthritis (RA), CT-P10 has demonstrated compelling similarity in pharmacokinetics, pharmacodynamics, efficacy, safety and immunogenicity (http://acrannualmeeting.org/abstracts/abstract-archives/,#1736 in 2013 and #1508 in 2014).This study is a randomized, parallel-group, active-controlled, double-blind, phase I/III study designed to demonstrate similarity in pharmacokinetics and non-inferiority in efficacy of CT-P10 to rituximab when co-administered with cyclophosphamide, vincristine, and prednisone (CVP) (NCT02162771). In this international multicenter trial, 134 patients with untreated advanced stage follicular lymphoma (AFL) will be administered CT-P10 or rituximab for 24 weeks at 3 weeks intervals, defined as Core Study Period. Patients who at least achieve a partial response after the Core Study Period will continue treatment with CT-P10 or rituximab as maintenance therapy over 24 months in 2 monthly intervals (Figure 1).The patients ≥18 years, with a histologically confirmed FL of grade 1 to 3a, Ann Arbor Stage III or IV disease, at least 1 measurable tumour mass that has not previously been irradiated, confirmed CD20+ lymphoma, ECOG performance status of 0-2, and adequate bone marrow, hepatic, and renal function reserves are included.The study has been initiated at >110 clinical sites across Europe, Latin America, Asia and Africa. Currently 83 patients were enrolled in this study, and a blinded initial review of initial safety data was carried out by the Data Safety Monitoring Board. As expected from the highly similar profile of CT-P10 accomplished through analytical studies and the CT-P10 RA trial (NCT01534884, NCT01873443), preliminary safety findings in terms of adverse events (AEs), serious AEs, AEs of special interest and survival characteristics with CT-P10 in AFL patients mirror those with the historical data of rituximab reference product. As currently 4 SAEs related to a study drug (CT-P10/Rituximab) were reported and these were resolved without sequelae. Qualitative feedback from study investigators throughout all regions indicates overall positive experience. Taken together, the study provides AFL patients with early access to a biosimilar investigational product assuring improved standards of care and long-term survival outcomes.In conclusion, it is expected that this ongoing study will demonstrate that CT-P10 is well tolerated in AFL patients with a similar safety profile to the rituximab reference product. [Display omitted] DisclosuresKim:CELLTRION, Inc.: Consultancy, Honoraria. Ogura:CELLTRION, Inc.: Consultancy, Honoraria. Buske:CELLTRION, Inc.: Consultancy, Honoraria. Coiffier:CELLTRION, Inc.: Consultancy, Honoraria. Sancho:CELLTRION, Inc.: Research Funding. Jurczak:CELLTRION, Inc,: Research Funding. Kim:CELLTRION, Inc,: Research Funding. Nagarkar:CELLTRION, Inc,: Research Funding. Zhavrid:CELLTRION, Inc,: Research Funding. Hernandez Rivas:CELLTRION, Inc.: Research Funding. Vinnyk:CELLTRION, Inc.: Research Funding. Tsirigotis:CELLTRION, Inc.: Research Funding. Viero:CELLTRION, Inc.: Research Funding. Volodicheva:CELLTRION, Inc.: Research Funding. Fourie:CELLTRION, Inc.: Research Funding. Soler:CELLTRION, Inc.: Research Funding.

SUVmax on Pre-Treatment FDG PET Scan Is Not Predictive of Outcome in Follicular Lymphoma after R-CHOP Threapy

Introduction: High standardized uptake value (SUV) on FDG PET scan in follicular lymphoma (FL) suggests aggressive disease and possible transformation to diffuse large B-cell lymphoma. Schoder et al, J Clin Oncol, 2005, reported that SUV >10 predicted aggressive lymphoma with >80% certainty and SUV >13 with >90% certainty. However, it is unknown whether the maximum SUV (SUVmax) on FDG PET scan at baseline, suggesting the possibility of focal aggressive or transformed disease, has prognostic value in FL. Here, we determined the prognostic value of SUVmax on baseline FDG PET scan in patients with advanced stage FL treated uniformly with R-CHOP chemoimmunotherapy at initial diagnosis.Methods: We reviewed medical records of all patients with stage III or IV FL who had FDG PET scan at initial diagnosis and were treated with R-CHOP chemoimmunotherapy at MD Anderson Cancer Center between January 2001 and December 2012. Patients with histological diagnosis of concurrent diffuse large B-cell lymphoma were excluded. Results: For the 225 patients studied, the median age was 57 years (range, 20-82). 83 (37%) patients were >= age 60, 137 (61%) had grade 1 or 2 FL, and 88 (39%) had grade 3A (n=57, 25%) or 3B (n=31, 14%). The Ki-67 score was <=40% for 85 (60%) patients and >40% for 56 (40%) patients. FLIPI risk groups were 54 patients (24%) low, 74 (33%) intermediate, and 97 (43%) high. GELF criteria were met in 133 (59%) patients. Tumor bulk of >= 6 cm was seen in 97 (43%) patients. The absolute lymphocyte count (ALC) was normal or high in 155 (69%) patients and low in 70 (31%). Sixty-nine (31%) patients received rituximab maintenance. There was no correlation between baseline SUVmax on FDG PET scan and Ki-67 score (Pearson correlation co-efficient of 0.168). The overall and complete response rates were 96% and 87%, respectively. The median follow-up time was 66 months. At 5 years, progression-free survival (PFS) was 85% and overall survival (OS) was 90%. Male gender, stage IV, high risk FLIPI, presence of GELF criteria, high beta-2 microglobulin, and low ALC were associated with significantly inferior PFS and OS (p<0.05). Histological grade was not associated with PFS or OS. Age >= 60 was associated with inferior OS but not PFS. Rituximab maintenance was associated with improved PFS but not OS. On baseline FDG PET scan, median SUVmax was 13.7 and the SUVmax range was 1.5-42.1. 105 (47%) patients had SUVmax <=13 and 120 (53%) had SUVmax >13. Patient characteristics including age, gender, histological grade, Ki-67 score, and FLIPI risk groups were not significantly different between the two SUVmax populations (p>0.05). The overall response rates were 94% and 96% for the SUVmax <=13 and SUVmax >13 groups, respectively. The complete response rate was 87% in both groups. At 5 years, the PFS and OS were not significantly different between the low and high SUVmax groups (61% vs 63% for PFS, p=0.98 and 90% vs 89% for OS, p=0.63). PFS and OS were not significantly different even when the patients were grouped into SUVmax <=10 vs >10 (p=0.9 and 0.61, respectively) or when other cut-offs were used. SUVmax was also not predictive of PFS and OS when only the patients meeting GELF criteria were analyzed.Conclusions: In this large cohort of advanced stage FL patients treated uniformly with R-CHOP chemoimmunotherapy, SUVmax on baseline FDG PET scan was not predictive of clinical outcome or correlated with other features. It is possible that the doxorubicin-based chemotherapy regimen may have benefited patients with high SUVmax who may have underlying aggressive or undiagnosed transformed disease. It remains to be determined whether SUVmax is predictive of clinical outcome in FL patients treated with other commonly used therapies such as rituximab monotherapy, rituximab and bendamustine, or R-CVP. [Display omitted] DisclosuresWang:Pharmacyclics, Janssen: Honoraria, Research Funding. Westin:Novartis: Research Funding.

Long-term survey of survival time, histological transformation, and secondary malignancies in Japanese patients with advanced-stage follicular lymphoma in the rituximab era: Hokkaido Hematology Study Group.

Following the introduction of rituximab, the long-term overall survival (OS) rate of advanced-stage follicular lymphoma (FL) cases was expected to improve after the introduction of rituximab: however, there is a lack of large-scale survey data in Asia due to the relatively low incidence of FL. We conducted a retrospective survey to assess the treatment outcomes in patients with newly diagnosed advanced-stage FL in 29 institutions in Hokkaido from January 2001 to December 2010. The total number of patients was 443 (men 47.6%, women 52.4%), with a median age of 55 years (range 20-80 years). Of the cases examined, 42.2% had stage III and 57.8% had stage IV disease. Furthermore, 62.5, 19.7, 9.2, 5.2, and 3.4% had performance statuses of 0, 1, 2, 3, and 4, respectively. The 5-year OS was 91.2%, and no survival plateau was observed. Seventeen patients experienced secondary malignancies (six hematological diseases and 11 solid cancers; 5-year probability, 4.2%). Eighteen patients experienced transformation (5-year probability, 4.5%). The overall survival at 5 years after therapy for transformation was 50%. Before the introduction of rituximab, the 5- to 10-year OS of advanced-stage FL patients in Japan was reported to be about 30-60%. Although these data are limited, improvement in OS has been observed in Japan during the rituximab era.

Denileukin diftitox in combination with rituximab for previously untreated follicular B-cell non-Hodgkin's lymphoma

Follicular lymphoma exhibits intratumoral infiltration by non-malignant T lymphocytes inluding CD4+CD25+ regulatory T (Treg) cells. We combined denileukin diftitox with rituximab in previously untreated, advanced-stage follicular lymphoma patients anticipating that denileukin diftitox would deplete CD25+ Treg cells while rituximab would deplete malignant B-cells. Patients received rituximab 375 mg/m2 weekly for 4 weeks and denileukin diftitox 18 mcg/kg/day for 5 days every 3 weeks for 4 cycles; neither agent was given as maintenance therapy. Between August 2008 and March 2010, 24 patients were enrolled. One patient died before treatment was given and was not included in the analysis. Eleven of 23 patients (48%; 95% CI: 27–69%) responded; 2 (9%) had complete responses and 9 (39%) had partial responses. The progression-free rate at 2 years was 55% (95%CI: 37–82%). Thirteen patients (57%) experienced grade ≥3 adverse events and 1 patient (4%) died. In correlative studies, soluble CD25 and the number of CD25+ T-cells decreased after treatment, however there was a compensatory increase in IL-15 and IP-10. We conclude that while the addition of denileukin diftitox to rituximab decreased the number of CD25+ T-cells, denileukin diftitox contributed to the toxicity of the combination without an improvement in response rate or time to progression.

Interferon Maintenance Prolongs Remission Duration After Rituximab-Containing Induction In First-Line Advanced Stage Follicular Lymphoma Patients – a Retrospective Analysis of the German Low-Grade Lymphoma Study Group (GLSG)

AbstractAbstract 2864 Background:Rituximab (R) maintenance in first remission of follicular lymphoma (FL) has recently been shown to improve remission duration as compared to observation only (Salles et al., ASCO 2010). During the nineties of the last century, maintenance using interferon alpha (IFN) had been shown to be effective in indolent lymphoma (Solal-Celigny et al., NEJM 1993, Hagenbeek et al., JCO 1998). Therefore IFN-maintenance became a standard in GLSG trials after 1995. However, data on the impact of IFN after R-containing chemotherapy are rare. We performed a retrospective analysis of GLSG trials in which we compared the outcome of patients who received IFN-maintenance and patients who did not start any form of consolidation or maintenance therapy after achieving a partial or complete remission. We adjusted the analysis for potential confounders that might have influenced the decision not to start IFN-maintenance. Methods:In the GLSG first-line trials “CHOP vs. MCP” and “CHOP vs. R-CHOP” patients younger than 60 years had been randomized between consolidating high-dose radiochemotherapy followed by autologous stem cell transplantation (ASCT) and IFN-maintenance. For all responding patients older than 60 years, IFN-maintenance was intended. All patients with FL achieving a partial or complete remission after MCP, CHOP, or R-CHOP who did not start ASCT were included in the current analysis. Patients intended for IFN who did not start IFN-maintenance were compared to patients who started IFN-maintenance. We compared patient and treatment characteristics between these groups in order to detect possible reasons why IFN-maintenance was not started. Remission duration (RD) was calculated from the end of induction to relapse or death. RD was censored at the latest follow-up date in patients without event, but also when a new antilymphoma therapy was initiated without any sign of progression. No censoring was done for any form of dose reduction or stopping of IFN, which was recommended in the trials if inacceptable side effects were observed. We compared RD with IFN-maintenance to observation only by Kaplan-Meier-curves and log rank test and we adjusted for the potential confounders FLIPI, performance status, R-containing induction and remission status in multiple Cox-Regression. In order to assess the impact of IFN-maintenance after R-containing induction, we performed a subgroup analysis of R-CHOP treated patients. Results:Of 1306 FL patients with clinical remission, ASCT was started in 306 patients and documentation concerning postremission therapy was missing in 21 patients. In 719 (73%) of the remaining 979 patients IFN-maintenance was started, whereas 260 patients did not receive IFN-maintenance. Patients in which IFN-maintenance was started were not more frequently younger than 60 years (59% vs. 55%, p=0.24), and not more frequently in a better performance status (ECOG 0–1: 93% vs. 91%, p=0.33). There was only a trend to better FLIPI (LR/IR/HR 13%/41%/46% vs. 15%/34%/52%, p=0.10) as compared to patients with observation only. Patients with IFN-maintenance had not more frequently achieved a CR (19% vs. 21%, p=0.65), but more patients had been treated without Rituximab during induction (57% vs. 37%, p<0.0001). According to our analysis patients with IFN-maintenance had a significantly prolonged RD (hazard ratio 0.73, 95% CI 0.59 to 0.91, p=0.0045) which was even more pronounced after adjustment for FLIPI factors, performance status, Rituximab containing induction, and remission status (adjusted hazard ratio 0.59, 95% CI 0.47 to 0.74, p<0.0001). In 309 (65%) of 473 patients treated with R-CHOP IFN-maintenance was started. RD after 3 years was 78% vs. 64% (p=0.0007) and the adjusted hazard ratio for IFN-maintenance was 0.57 (95% CI 0.39 to 0.84 p=0.0042). Conclusions:Although this is not a randomized comparison, our analysis shows that the impact of IFN, which was observed before using R-containing therapy may still be valid in the era of immunochemotherapy. Since R-maintenance seems more effective and has less side effects, IFN-maintenance will no longer be the first choice for maintenance therapy in FL. However, it seems relevant to keep in mind that IFN is still an active substance in lymphoma therapy and may be a therapeutic option when rituximab maintenance is not possible. It may also be relevant for future investigations in lymphoma therapy. Disclosures:Dreyling:Johnson & Johnson:.Hiddemann:Roche: Honoraria, Research Funding.

Phase II Clinical Trial of Denileukin Diftitox In Combination with Rituximab In Previously Untreated Follicular B-Cell Non-Hodgkin's Lymphoma

AbstractAbstract 2862Follicular lymphoma (FL) is a B-cell malignancy that exhibits significant intratumoral infiltration by non-malignant T lymphocytes. The pathophysiological significance of infiltrating T cells is poorly understood but recent studies have suggested that CD4+CD25+ regulatory T (Treg) cells are highly represented in lymph nodes involved by FL. These Treg cells display the ability to suppress the proliferation and cytokine production of other tumor-infiltrating T cells and migrate to areas of B-cell lymphoma in response to chemotactic signals provided by the malignant B-cells. Denileukin diftitox, a chimeric immunotoxin composed of the modified cytotoxic domain of diphtheria toxin and human interleukin-2 (IL-2) protein, targets cells expressing CD25 and has proven efficacy in patients with relapsed B-cell lymphoma. In this study, we combined denileukin diftitox with rituximab in a cohort of previously untreated, advanced-stage follicular lymphoma patients. Our hypothesis was that denileukin diftitox would deplete the Treg cells, thereby removing the inhibition of the immune response, and rituximab would deplete the B-cells thereby preventing further recruitment of Treg cells to the areas of lymphoma.Between August 2008 and March 2010, twenty-four patients with stage III and IV follicular grade 1 or 2 non-Hodgkin lymphoma were accrued to the study. One patient died before treatment was given and is not included in the analysis. The median age was 60 years (range: 27 – 79), 12 (52%) of the patients were male, 19 (83%) had a PS of 0 and 4 (17%) had a PS of 1. Based on the Follicular Lymphoma International Prognostic Index (FLIPI), 3 (13%) were low risk, 14 (61%) were intermediate risk and 6 (26%) were high risk. Patients received rituximab 375 mg/m2 on days 1, 8, 15 and 22 and denileukin diftitox 18 mcg/kg/day on days 1–5 every 3 weeks for 4 cycles. A median of 4 cycles of therapy was given (range: 1 – 4). Thirteen patients completed treatment per protocol (57%), however 5 patients discontinued treatment due to adverse events (22%), 2 refused further treatment (9%) and 1 discontinued due to disease progression (4%). Nine of the 23 patients (39%; 95% CI: 21–61%) responded to treatment, 3 (13%) had a complete response and 6 (26%) had a partial response. Twenty-one patients (91%) are alive with a median follow-up of 8.7 months (range: 3.4–19.5). Seven (30%) patients have progressed and two (8.7%) has died. The median time to progression is 13.4 months (95% CI: 10.4 – NA). The combination, however, was associated with significant toxicity. Thirteen patients (57%) experienced grade 3 or greater adverse events. Six patients (26%) had symptoms of capillary leak syndrome, 1 of whom died. In correlative studies performed on the peripheral blood, the number of CD25+ T-cells decreased after treatment when compared to pretreatment numbers (median 24%; range: 8–44%).We conclude that while the addition of denileukin diftitox to rituximab decreased the numbers of CD25+ T-cells, denileukin diftitox contributed significantly to the toxicity of the combination. Furthermore, the overall response rate and time to progression in this study were no better than what would be expected in follicular lymphoma patients treated with rituximab alone. Disclosures:No relevant conflicts of interest to declare.

The architectural pattern of FOXP3-positive T cells in follicular lymphoma is an independent predictor of survival and histologic transformation

AbstractPrevious studies of follicular lymphoma (FL) patients treated heterogeneously have suggested that decreased numbers of regulatory T cells correlates with improved survival. We studied advanced-stage FL patients from a single institution phase 2 trial. All patients were treated uniformly with multiagent chemotherapy and radiation. Tissue microarrays were constructed using diagnostic biopsies available in 105 patients and stained with CD4, CD8, CD25, and forkhead/winged helix transcription factor 3 (FOXP3) antibodies. Both cell content and cell distribution were evaluated. For all antibodies, there were cases with a predominant intrafollicular or perifollicular localization of cells (follicular pattern) while others displayed a diffuse pattern. The median follow-up of living patients was 17.1 years. The International Prognostic Index score predicted overall survival (OS; P = .004) but not risk of transformation (RT). Cell content did not impact survival, while immunoarchitectural patterns of CD4/CD8 were significant for progression-free survival (PFS; P = .056), CD25 for both PFS and OS (P = .002 and P = .024, respectively), and FOXP3+ predicted PFS, OS, and RT (P = .001, P < .001 and p = .002, respectively). A Cox multivariate model showed both International Prognostic Index score and FOXP3+ pattern were independent predictors of OS (P = .008 and P < .001, respectively), while only FOXP3+ pattern predicted RT (P = .004). We conclude that FOXP3+ cell distribution significantly predicts survival and RT in FL.

Combined FOXP3+ and PD1+ T Cell Density and Architectural Patterns Predict Overall Survival and Risk of Transformation in Uniformly Treated Patients with Follicular Lymphoma

Background: Follicular lymphoma (FL) is an indolent heterogeneous lymphoid neoplasm with a variable clinical course. Transformation into an aggressive lymphoma is a dominant clinical event frequently associated with inferior survival. No consistent biological markers are predictive of survival or risk of transformation (RT). Recent studies have highlighted the role of the microenvironment, including regulatory T cells (Treg) as important prognostic factors in FL. Using tissue microarrays (TMA), we previously identified FOXP3+ T cell distribution but not cell density within the tumor is an independent adverse prognostic factor for both overall survival (OS), progression-free (PFS) survival and RT in advanced-stage FL pts treated uniformly with an aggressive treatment regimen (ASH 2007). Programmed death-1(PD1) belongs to the immunoglobulin CD28 receptor family and is characteristically expressed by germinal center associated T cells. They have imunoregulatory activity and are FOXP3-negative. Using the same cohort we assessed the role of PD1+ cells alone and in combination with FOXP3+ cells in FL prognosis.Methods: Between 1987 and 1993, 126 pts were enrolled on a phase II study of BP-VACOP chemotherapy with involved region radiotherapy. All patients were treatment naive, < 61y and had advanced-stage FL. Paraffin blocks were available for 105 pts. TMAs consisted of duplicate 1.0mm cores of diagnostic biopsies and were immunostained with both FOXP3 and PD1 (NAT105) specific antibodies. Both cell content and immuno-architectural patterns were determined and correlated with OS and RT including univariate and multivariate analysis.Results: There were 101 evaluable cases. The median follow-up of the living pts was 14 years. Histologic grade included 78 grade 1, 17 grade 2 and 6 grade 3a FLs. The IPI was predictive of OS (RR = 2.5, 95% CI =1.5–4.4, p = 0.002), but not RT (p = 0.14). Cases revealed zero to 731 FOXP3+ cells per core (median of 242 cells per core) and zero to 654 PD1+ cells per core (median of 102 cells per core). There was a predominantly intrafollicular or perifollicular localization of positive cells (“follicular pattern”) in 38 and 43 pts for FOXP3 and PD1, respectively. There was no significant correlation between cell density (χ2=0.1) or pattern (χ2=0.8) between markers. Separately, cell density did not impact prognosis. Yet, when quartiles were combined and dichotomized, cases with high cell content of FOXP3+/PD1+ cells correlated with inferior OS and increased RT in univariate (p = 0.002 and p = 0.01) and multivariate Cox models (RR = 2.18, 95% CI =1.2–3.9, p = 0.01 & RR = 3.4, 95% CI =1.3–8.8, p = 0.015). In univariate analysis, a PD1 follicular pattern correlated with inferior OS (p=0.027) but did not impact RT. When combined with follicular FOXP3+ cases, a subset of 15 “double follicular” FOXP3 & PD1 cases correlated with inferior OS in univariate (p=0.0016) and multivariate Cox models (RR = 2.1, 95% CI =1–4.3, p = 0.04). This subset of cases also showed a trend for increased RT (p = 0.09).Conclusions: Combined cell density and distribution within FL of immuno-regulatory T cell subsets are important predictors of OS & RT in advanced-stage FL patients treated uniformly with an aggressive treatment regimen. Our results reinforce the importance of the microenvironment in FL biology and further suggest an active role for immuno-modulatory T cells in pro-tumoral immunity.

Rapid and sustained clearance of circulating lymphoma cells after chemotherapy plus rituximab: clinical significance of quantitative t(14;18) PCR monitoring in advanced stage follicular lymphoma patients†

This study of first-line treatment in advanced-stage follicular lymphoma patients analysed the effects of MCP (mitoxantrone, chlorambucil and prednisolone) chemotherapy alone or in combination with rituximab (R-MCP) on circulating lymphoma cells (CLC) and assessed the prognostic value of a quantitative monitoring of CLC. CLC numbers were determined by quantitative polymerase chain reaction (PCR) for the t(14;18)-translocation or by allele-specific PCR for rearranged immunoglobulin heavy chain genes. We analysed blood samples from 43 patients treated in a randomized trial comparing eight cycles of MCP versus R-MCP. Clearance of CLC at the end of therapy was achieved in 21/25 patients (84%) treated with R-MCP compared with 0/18 after MCP alone (P < 0.0001). A > or = 2 log CLC reduction was associated with a favourable clinical response (P = 0.0004) and prolonged event-free survival (P = 0.02). In R-MCP patients, stable CLC numbers or consistently PCR-negative blood samples were associated with a continuing clinical remission whereas in two patients a relapse was preceded by a > or = 2 log CLC increase. This study demonstrated that R-MCP led to a rapid and sustained eradication of CLC and a > or = 2 log CLC reduction was associated with a superior quality and duration of the clinical response.

The Architecural Pattern of FOXP3+ T Cells Predicts Risk of Transformation in Patients with Follicular Lymphoma (FL).

Background: FL is an indolent heterogeneous lymphoid neoplasm with a variable clinical course. Transformation into an aggressive lymphoma (Tly) is a dominant clinical event frequently associated with inferior survival. No consistent biological markers have been identified that predict for Tly. Recent studies have highlighted the role of the microenvironment, including lymphoma-associated-macrophages (LAM) and Treg cells as important prognostic factors in FL. The nuclear expression of FOXP3 is considered a specific marker of regulatory T cells (Treg). However, most series have included pts variably treated with a wide spectrum of protocols. Using tissue microarrays (TMA) we recently demonstrated that both LAM content and follicular/perifollicular pattern of FOXP3+ T cells are independent adverse prognostic factors for both overall (OS) and progression-free (PFS) survival in advanced-stage FL patients treated uniformly with an aggressive regimen. However, the impact of either LAM or Tregs on Tly is largely unknown. Using the same cohort we assessed the role of these cell types for predicting Tly.Methods: Between 1987 and 1993, 126 pts were enrolled on a phase II study of BP-VACOP chemotherapy with involved region radiotherapy. All patients were treatment naïve, < 61y and had advanced-stage FL. Paraffin blocks were available in 105 patients. The TMAs consisted of duplicate 1.0mm cores of diagnostic biopsies and were immunostained with both CD68 and a FOXP3-specific antibody. Both CD68+ macrophage content and FOXP3+ T cell content and immuno-architectural patterns were determined and correlated with RT including univariate and multivariate analyses.Results: There were 102 evaluable cases. The median follow-up of the living pts was 14.3 years and the estimated 10-year OS and Tly rates were 63% and 18%, respectively. The IPI was predictive of OS (RR = 2.4, 95% CI =1.4–4.2, p = 0.002) but not Tly (RR = 2.2, 95% CI =.9–5.1, p = 0.07). Histologic grade included 76 grade 1, 20 grade 2 and 6 grade 3a FLs. Cases revealed 1 to 28 CD68+ cells per high power field (median 7 cells/hpf) and zero to 731 FOXP3+ cells per core (median of 242 cells/core). In 38 pts there was a predominantly intrafollicular or perifollicular localization of positive cells (“follicular Treg pattern”) and in 64 pts the pattern was diffuse. Neither LAM content nor number of FOXP3+ cells had any impact on Tly. However, the immuno-architectural pattern of FOXP3+ cells was predictive of Tly, with the “follicular” pattern showing increased risk of Tly in univariate analysis (p=0.005). A Cox multivariate model including IPI and LAM showed only the FOXP3+ Treg pattern as an independent predictor of Tly (RR = 3.9, 95% CI =.1.5–9.9, p = 0.004).Conclusions: Treg cell distribution within the tumor is an important predictor of Tly in advanced-stage FL patients treated uniformly with an aggressive treatment regimen. Our results reinforce the importance of a FOXP3 follicular pattern as a good surrogate for functionally active Treg cells within the tumor microenvironment and further highlight the important role of the tumor microenvironment in FL biology. [Display omitted]

Introduction of rituximab in front‐line and salvage therapies has improved outcome of advanced‐stage follicular lymphoma patients

It is unclear whether new treatment modalities have improved the survival of follicular lymphoma patients. Some data show that there has been no improvement in survival in the last 3 decades of the 20th century, whereas the results of recent retrospective studies suggest that evolving therapy has improved the outcome for follicular lymphoma patients. To evaluate the impact of evolving therapies for follicular lymphoma, particularly the introduction of rituximab, the overall survival (OS), failure-free survival (FFS), and survival after recurrence (SAR) was analyzed in 438 advanced-stage follicular lymphoma patients enrolled in consecutive Gruppo Italiano Studio Linfomi (GISL) trials between 1988 and 2004. A stepwise improvement in FFS and a significant reduction in the hazard ratio was observed with succeeding studies. Cox regression analysis showed an improvement over time for OS, with a decline in the hazard ratio particularly evident in the group treated with rituximab. Furthermore, the SAR significantly improved in the group of patients treated with chemotherapy + rituximab. After adjusting for all parameters with an impact on FFS and OS, the results of multivariate analysis suggest that rituximab therapy has a favorable effect on the prognosis of follicular lymphoma. The data show that FFS and OS have significantly improved in advanced-stage follicular lymphoma patients treated on GISL protocols during the last 18 years. These improvements are related to evolving front-line and salvage therapies, particularly the introduction of rituximab in combination with chemotherapy.

Prognostic Significance of Quantitative t(14;18) PCR Monitoring in Advanced Stage Follicular Lymphoma Patients.

In a prospective multicenter phase III trial (M 39023) advanced stage follicular lymphoma (FL) patients were randomized to receive eight cycles of MCP (mitoxantrone, chlorambucil, prednisolone) chemotherapy alone or in combination with rituximab (R-MCP). This study was carried out to determine the effects of this therapy on circulating lymphoma cells (CLC) and to assess the value of CLC quantitation as a molecular marker of disease activity and as a prognostic parameter. CLC numbers were determined by real-time quantitative PCR for the t(14;18)-MBR translocation or by allele-specific PCR for rearranged immunoglobulin heavy chain genes. Quantitative PCR of a reference gene (wild type K-ras) allowed the exact quantitation of cells tested per sample and to exclude samples with insufficient DNA content (< 500,000 cells). We analyzed serial blood samples from 43 patients obtained before, during and after completion of therapy. Baseline clinical characteristics and response to therapy of the 43 patients of this study were not significantly different to all 201 FL patients of the clinical trial except for a higher complete response (CR) rate in the R-MCP group (18/25 (72%) in this study versus 52/105 (50%) in the clinical trial, p=.04). Similar to the results of the clinical study, response rate and CR rate in the present study were significantly higher in the R-MCP arm than after therapy with MCP alone (25/25 (100%) versus 13/18 (72%), p= .009, and 18/25 (72%) versus 5/18 (28%), p= .006, respectively). Clearance of CLC at the end of therapy was achieved in 21/25 patients (84%) treated with R-MCP compared to 0/18 (0%) after MCP alone (p< .0001). R-MCP patients achieved a greater reduction of CLC after completion of therapy and a greater reduction of CLC per treatment cycle than patients treated with MCP alone, even if the comparison was restricted to patients with clinical response (3.88 log and 1.18 log reduction versus 2.21 log and 0.23 log reduction, p= .001 and p< .0001). A ≥ 2 log reduction of CLC after completion of therapy was associated with a favourable clinical response (p= 0.0007) and prolonged event-free survival (p= 0.02) regardless of treatment arm. Among patients with a ≥2 log CLC reduction there was no significant difference in EFS between patients with PCR negative samples and patients with PCR positive blood samples at completion of therapy (p= 0.091). In conclusion, R-MCP led to a rapid and sustained eradication of CLC in the majority of patients. The results of serial determinations of CLC numbers showed a good correlation with the quality and duration of the clinical response. Therefore, quantitative molecular disease monitoring could help to develop individualized treatment strategies for patients with advanced stage FL.