Guillaume Cartron

Rituximab-Dependent Cytotoxicity by Natural Killer Cells Influence of FCGR3A Polymorphism on the Concentration-Effect Relationship

The FCGR3A gene dimorphism generates two allotypes: FcγRIIIa-158V and FcγRIIIa-158F. The genotype homozygous for FcγRIIIa-158V (VV) is associated with higher clinical response to rituximab, a chimeric anti-CD20 IgG1 used in the treatment of B lymphoproliferative malignancies. Our objective was to determine whether this genetic association relates to rituximab-dependent cytotoxicity mediated by FcγRIIIa/CD16a+ cells. The number of CD16+ circulating monocytes, T cells, and natural killer (NK) cells in 54 donors was first shown to be unrelated to FCGR3A polymorphism. We then demonstrated that FcγRIIIa-158V displays higher affinity for rituximab than FcγRIIIa-158F by comparing rituximab concentrations inhibiting the binding of 3G8 mAb (anti-CD16) with VV NK cells and NK cells homozygous for FcγRIIIa-158F (FF). VV and FF NK cells killed Daudi cells similarly after FcγRIIIa engagement by saturating concentrations of rituximab or 3G8. However, the rituximab concentration resulting in 50% lysis (EC50) observed with NK cells from VV donors was 4.2 times lower than that observed with NK cells from FF donors (on average 0.00096 and 0.00402 μg/ml, respectively, P = 0.0043). Finally, the functional difference between VV and FF NK cells was restricted to rituximab concentrations weakly sensitizing CD20. This study supports the conclusion that FCGR3A genotype is associated with response to rituximab because it affects the relationship between rituximab concentration and NK cell-mediated lysis of CD20+ cells. Rituximab administration could therefore be adjusted according to FCGR3A genotype.

Phase 1 study results of the type II glycoengineered humanized anti-CD20 monoclonal antibody obinutuzumab (GA101) in B-cell lymphoma patients

Whereas the chimeric type I anti-CD20 Ab rituximab has improved outcomes for patients with B-cell malignancies significantly, many patients with non-Hodgkin lymphoma (NHL) remain incurable. Obinutuzumab (GA101) is a glycoengineered, humanized anti-CD20 type II Ab that has demonstrated superior activity against type I Abs in vitro and in preclinical studies. In the present study, we evaluated the safety, efficacy, and pharmacokinetics of GA101 in a phase 1 study of 21 patients with heavily pretreated, relapsed, or refractory CD20(+) indolent NHL. Patients received GA101 in a dose-escalating fashion (3 per cohort, range 50/100-1200/2000 mg) for 8 × 21-day cycles. The majority of adverse events (AEs) were grades 1 and 2 (114 of 132 total AEs). Seven patients reported a total of 18 grade 3 or 4 AEs. Infusion-related reactions were the most common AE, with most occurring during the first infusion and resolving with appropriate management. Three patients experienced grade 3 or 4 drug-related infusion-related reactions. The best overall response was 43%, with 5 complete responses and 4 partial responses. Data from this study suggest that GA101 was well tolerated and demonstrated encouraging activity in patients with previously treated NHL up to doses of 2000 mg. This trial is registered at www.clinicaltrials.gov as NCT00517530.

Obinutuzumab (GA101) in Patients With Relapsed/Refractory Indolent Non-Hodgkin Lymphoma: Results From the Phase II GAUGUIN Study

PURPOSE The phase II part of the phase I/II GAUGUIN study evaluated the efficacy and safety of two different doses of obinutuzumab (GA101), a type II, glycoengineered, humanized anti-CD20 monoclonal antibody, in patients with relapsed/refractory indolent non-Hodgkin lymphoma. PATIENTS AND METHODS Patients were randomly assigned to receive eight cycles of obinutuzumab (GA101) as a flat dose of 400 mg on days 1 and 8 of cycle 1 and also on day 1 of cycles 2 to 8 (400/400 mg) or 1,600 mg on days 1 and 8 of cycle 1 and 800 mg on day 1 of cycles 2 to 8 (1,600/800 mg). RESULTS Forty patients were enrolled, including 34 with follicular lymphoma; 38 of 40 patients had previously received rituximab and 22 of 40 were rituximab refractory. The overall response rate at the end of treatment was 55% (95% CI, 32% to 76%) in the 1,600/800-mg group (9% complete responders) and 17% (95% CI, 4% to 41%) in the 400/400-mg group (no complete responders). Five of 10 rituximab-refractory patients had an end-of-treatment response in the 1,600/800-mg group versus one of 12 in the 400/400-mg group. Median progression-free survival was 11.9 months in the 1,600/800-mg group (range, 1.8 to 33.9+ months) and 6.0 months in the 400/400-mg group (range, 1.0 to 33.9+ months). The most common adverse events were infusion-related reactions (IRRs) seen in 73% of patients, but only two patients had grade 3 to 4 IRRs (both in the 1,600/800-mg group). No IRRs were considered serious, and no patients withdrew for IRRs. CONCLUSION The 1,600/800-mg dose schedule of obinutuzumab (GA101) has encouraging activity with an acceptable safety profile in relapsed/refractory indolent non-Hodgkin lymphoma.

Ofatumumab monotherapy in rituximab-refractory follicular lymphoma: results from a multicenter study

New treatments are required for rituximab-refractory follicular lymphoma (FL). In the present study, patients with rituximab-refractory FL received 8 weekly infusions of ofatumumab (CD20 mAb; dose 1, 300 mg and doses 2-8, 500 or 1000 mg; N = 116). The median age of these patients was 61 years, 47% had high-risk Follicular Lymphoma International Prognostic Index scores, 65% were chemotherapy-refractory, and the median number of prior therapies was 4. The overall response rate was 13% and 10% for the 500-mg and 1000-mg arms, respectively. Among 27 patients refractory to rituximab monotherapy, the overall response rate was 22%. The median progression-free survival was 5.8 months. Forty-six percent of patients demonstrated tumor reduction 3 months after therapy initiation, and the median progression-free survival for these patients was 9.1 months. The most common adverse events included infections, rash, urticaria, fatigue, and pruritus. Three patients experienced grade 3 infusion-related reactions, none of which were considered serious events. Grade 3-4 neutropenia, leukopenia, anemia, and thrombocytopenia occurred in a subset of patients. Ofatumumab was well tolerated and modestly active in this heavily pretreated, rituximab-refractory population and is therefore now being studied in less refractory FL and in combination with other agents in various B-cell neoplasms. The present study was registered at www.clinicaltrials.gov as NCT00394836.

Obinutuzumab (GA101) in relapsed/refractory chronic lymphocytic leukemia: final data from the phase 1/2 GAUGUIN study

GAUGUIN evaluated the safety and efficacy of obinutuzumab (GA101) monotherapy in patients with relapsed/refractory chronic lymphocytic leukemia (CLL). In phase 1 (dose escalation), 13 patients received obinutuzumab 400 to 1200 mg (days 1 and 8 of cycle 1; day 1 of cycles 2-8). In phase 2, 20 patients received a fixed dose of 1000 mg (days 1, 8, and 15 of cycle 1; day 1 of cycles 2-8). Infusion-related reactions occurred in nearly all patients, but few were grade 3/4. Grade 3/4 neutropenia occurred in 7 patients in phase 1 (but was not dose-related) and in 4 patients in phase 2. Overall end-of-treatment response (all partial responses) was 62% (phase 1) and 15% (phase 2); best overall response was 62% and 30%, respectively. Phase 2 median progression-free survival was 10.7 months and median duration of response was 8.9 months. In summary, obinutuzumab monotherapy is active in patients with heavily pretreated relapsed/refractory CLL.

Tumor burden influences exposure and response to rituximab: pharmacokinetic-pharmacodynamic modeling using a syngeneic bioluminescent murine model expressing human CD20

Clinical studies have shown a large interindividual variability in rituximab exposure and its significant influence on clinical response in patients receiving similar doses of antibody. The aim of this study was to evaluate the influence of tumor burden on dose-concentration-response relationships of rituximab. Murine lymphoma cells (EL4, 8 x 10(3)), transduced with human CD20 cDNA and transfected with luciferase plasmid (EL4-huCD20-Luc), were intravenously injected into C57BL/6J mice. Tumor burden detection, dissemination, and progression were evaluated quantitatively by in vivo bioluminescence imaging. Different doses of rituximab (6, 12, 20, or 40 mg/kg) were infused 13 days after lymphoma cell inoculation, and rituximab serum concentrations were measured by enzyme-linked immunosorbent assay. Without rituximab, all mice developed disseminated lymphoma and died within 30 days, whereas a significant dose-response relationship was observed in mice receiving rituximab. The 20-mg/kg dose was adequate to study interindividual variability in response because 23% of mice were cured, 59% had partial response, and 18% had disease progression. Rituximab concentrations were inversely correlated with tumor burden; mice with low tumor burden had high rituximab concentrations. Furthermore, rituximab exposure influenced response and survival. Finally, using a pharmacokinetic-pharmacodynamic model, we demonstrated that tumor burden significantly influenced rituximab efficacy.

Results From a Prospective, Open-Label, Phase II Trial of Bendamustine in Refractory or Relapsed T-Cell Lymphomas: The BENTLY Trial

PURPOSE To determine the efficacy and safety of bendamustine as a single agent in refractory or relapsed T-cell lymphomas. PATIENTS AND METHODS Patients with histologically confirmed peripheral T-cell lymphoma (PTCL) or cutaneous T-cell lymphoma who progressed after one or more lines of prior chemotherapy received bendamustine at 120 mg/m(2) per day on days 1 through 2 every 3 weeks for six cycles. The primary end point was overall response rate (ORR). Secondary end points were duration of response (DOR), progression-free survival (PFS), and overall survival (OS). RESULTS Of the 60 patients included, 27 (45%) were refractory to their last prior chemotherapy, and the median duration of the best previous response was 6.6 months. Histology was predominantly angioimmunoblastic lymphadenopathy and PTCL not otherwise specified. The disease was disseminated in the majority of patients (87%). The median number of previous lines of chemotherapy was one (range, one to three). Twenty patients (33%) received fewer than three cycles of bendamustine, mostly because of disease progression. In the intent-to-treat population, the ORR was 50%, including complete response in 17 patients (28%) and partial response in 13 patients (22%). Bendamustine showed consistent efficacy independent of major disease characteristics. The median values for DoR, PFS, and OS were 3.5, 3.6, and 6.2 months, respectively. The most frequent grade 3 to 4 adverse events were neutropenia (30%), thrombocytopenia (24%), and infections (20%). CONCLUSION Bendamustine showed an encouraging high response rate across the two major PTCL subtypes, independent of age and prior treatment, with acceptable toxicity in refractory or relapsed T-cell lymphoma.

Clinical radioimmunotherapy—the role of radiobiology

Conventional external-beam radiation therapy is dedicated to the treatment of localized disease, whereas radioimmunotherapy represents an innovative tool for the treatment of local or diffuse tumors. Radioimmunotherapy involves the administration of radiolabeled monoclonal antibodies that are directed specifically against tumor-associated antigens or against the tumor microenvironment. Although many tumor-associated antigens have been identified as possible targets for radioimmunotherapy of patients with hematological or solid tumors, clinical success has so far been achieved mostly with radiolabeled antibodies against CD20 (131I-tositumomab and 90Y-ibritumomab tiuxetan) for the treatment of lymphoma. In this Review, we provide an update on the current challenges aimed to improve the efficacy of radioimmunotherapy and discuss the main radiobiological issues associated with clinical radioimmunotherapy.

A phase 1 clinical trial of the selective BTK inhibitor ONO/GS-4059 in relapsed and refractory mature B-cell malignancies

We report the results of a multicenter phase 1 dose-escalation study of the selective Bruton tyrosine kinase (BTK) inhibitor ONO/GS-4059 in 90 patients with relapsed/refractory B-cell malignancies. There were 9 dose-escalation cohorts ranging from 20 mg to 600 mg once daily with twice-daily regimens of 240 mg and 300 mg. Twenty-four of 25 evaluable chronic lymphocytic leukemia (CLL) patients (96%) responded to ONO/GS-4059, with a median treatment duration of 80 weeks; 21 CLL patients remain on treatment. Lymph node responses were rapid and associated with a concurrent lymphocytosis. Eleven of 12 evaluable patients with mantle cell lymphoma (92%) responded (median treatment duration, 40 weeks). Eleven of 31 non-germinal center B-cell diffuse large B-cell lymphoma patients (35%) responded but median treatment duration was 12 weeks due to development of progressive disease. ONO/GS-4059 was very well tolerated with 75% of adverse events (AEs) being Common Toxicity Criteria for Adverse Events version 4.0 grade 1 or grade 2. Grade 3/4 AEs were mainly hematologic and recovered spontaneously during therapy. One CLL patient experienced a grade 3 treatment-related bleeding event (spontaneous muscle hematoma) but no clinically significant diarrhea, cardiac dysrhythmias, or arthralgia were observed. No maximal tolerated dose (MTD) was reached in the CLL cohort. In the non-Hodgkin lymphoma cohort, 4 patients developed a dose-limiting toxicity, yielding an MTD of 480 mg once daily. ONO/GS-4059 has significant activity in relapsed/refractory B-cell malignancies without major drug-related toxicity. The selectivity of ONO/GS-4059 should confer advantages in combination therapies. This trial was registered at www.clinicaltrials.gov as #NCT01659255.

Impact of the use of autologous stem cell transplantation at first relapse both in naïve and previously rituximab exposed follicular lymphoma patients treated in the GELA/GOELAMS FL2000 study

Background We analyzed detailed characteristics and salvage treatment in 175 follicular lymphoma patients from the FL2000 study who were in progression after first-line therapy with or without addition of rituximab to chemotherapy and interferon. Design and Methods The impact of using autologous stem cell transplantation and/or rituximab administration at first progression was investigated, taking into account initial therapy. With a median follow up of 31 months, 3-year event free and overall survival rates after progression were 50% (95%CI 42–58%) and 72% (95%CI 64–78%), respectively. Results The 3-year event free rate of rituximab re-treated patients (n=112) was 52% (95%CI 41–62%) versus 40% (95%CI 24–55%) for those not receiving rituximab second line (n=53) (P=0.075). There was a significant difference in 3-year overall survival between patients receiving autologous stem cell transplantation and those not: 92% (95%CI 78–97%) versus 63% (95%CI 51–72%) (P=0.0003), respectively. In multivariate analysis, both autologous stem cell transplantation and period of progression/relapse affected event free and overall survival. Conclusions Regardless of front-line rituximab exposure, this study supports incorporating autologous stem cell transplantation in the therapeutic approach at first relapse for follicular lymphoma patients.