An open-label, single-arm, phase 1 study to assess biomarker effects, efficacy and safety of ofatumumab in patients with refractory chronic lymphocytic leukemia.
ABSTRACT: This open-label, phase 1 study evaluated the effects of ofatumumab on QTc intervals, safety, efficacy, B-cell and neutrophil counts, complement levels, and cytokine and chemokine concentrations. Fourteen patients with fludarabine-refractory chronic lymphocytic leukemia received 12 ofatumumab infusions. A higher maximum infusion rate of 400 mL/h was tested at the first two doses and was well tolerated. The 43% overall response rate was similar to previous data (42-51%). B-cell depletion was observed along with complement consumption; median C2 and CH50 levels appeared lower during monthly dosing in patients who responded. Responding patients appeared to have higher median levels of certain pro-inflammatory cytokines and lower median levels of certain immunotolerant cytokines than patients who did not respond. Ofatumumab-induced complement-dependent cytotoxicity activity can be detected clinically by measuring complement and may be associated with clinical activity. The potential relationship between changes in complement or cytokines and clinical response to ofatumumab warrants further study.
Project description:Background:While many humanized monoclonal antibodies utilize complement-dependent cytotoxicity, the complement depleting effects of these antibodies and the impact of complement replacement on treatment response are not well-described. Methods:We conducted a phase 2 trial involving patients with relapsed/refractory chronic lymphocytic leukemia (CLL). Patients were treated with ofatumumab with fresh frozen plasma (FFP) used as a source of complement replacement. The primary endpoint was objective response rate. Correlative endpoints included complement levels (C3 and C4) and complement activity (CH50) which was drawn at baseline and after ofatumumab with FFP administration. Results:Among 12 enrolled patients, overall response rate was 83% with two patients (17%) achieving a complete response. While only two (17%) patients had low complement activity at baseline, eight (67%) developed low levels of complement activity after ofatumumab treatment with FFP replacement. The magnitude of complement depletion did not correlate with response. Adverse events were minimal. The combination of ofatumumab and FFP demonstrated tolerability and surprising activity in high-risk CLL patients. Conclusions:The combination of ofatumumab and FFP demonstrated tolerability and surprising activity in high-risk CLL patients. Complement replacement should be studied further as a minimally toxic approach to improve efficacy of monoclonal antibody-based regimens.
Project description:Although rituximab-based chemoimmunotherapy (CIT) has substantially improved clinical outcomes in chronic lymphocytic leukemia (CLL), only 40% to 50% of patients achieve a complete remission (CR). There remains interest in identifying new approaches to improve the effectiveness of CIT. Ofatumumab is a fully human anti-CD20 monoclonal antibody with greater apparent single-agent activity than rituximab in CLL patients.Previously untreated CLL patients in need of therapy received 6 cycles of CIT induction with pentostatin, cyclophosphamide, and ofatumumab (PCO) followed by response assessment.Of the 48 patients enrolled, 77% completed PCO induction. Adverse events during induction included grade 3+ hematologic toxicity (27%) and grade 3+ nonhematologic toxicity (23%). Median CD4 count after induction and 6 months later were 186 × 10(6)/L and 272 × 10(6) /L. The overall response rate was 96% (46 of 48 patients), and the CR rate was 46% (22 of 48 patients). Among the 38 patients who underwent minimal residual disease evaluation, 7 (18%) were negative for minimal residual disease. After median follow-up of 24 months, 10 (21%) patients have progressed and 8 (17%) have required retreatment. The efficacy and toxicity of ofatumumab-based CIT compare favorably to our historical trials of rituximab-based CIT using an identical chemotherapy backbone (n = 64). Time to retreatment also appeared longer for ofatumumab-based CIT (free of retreatment at 24 months: 86% [95% confidence interval = 75-99] versus 68% [95% confidence interval = 56-81] for rituximab-based CIT).Ofatumumab-based CIT is well tolerated in patients with previously untreated CLL. The efficacy of ofatumumab-based CIT compares favorably to historical trials of rituximab-based CIT, suggesting randomized trials comparing ofatumumab-based CIT and rituximab-based CIT should be considered.
Project description:In patients with chronic lymphoid leukemia (CLL) or small lymphocytic lymphoma (SLL), a short duration of response to therapy or adverse cytogenetic abnormalities are associated with a poor outcome. We evaluated the efficacy of ibrutinib, a covalent inhibitor of Bruton's tyrosine kinase, in patients at risk for a poor outcome.In this multicenter, open-label, phase 3 study, we randomly assigned 391 patients with relapsed or refractory CLL or SLL to receive daily ibrutinib or the anti-CD20 antibody ofatumumab. The primary end point was the duration of progression-free survival, with the duration of overall survival and the overall response rate as secondary end points.At a median follow-up of 9.4 months, ibrutinib significantly improved progression-free survival; the median duration was not reached in the ibrutinib group (with a rate of progression-free survival of 88% at 6 months), as compared with a median of 8.1 months in the ofatumumab group (hazard ratio for progression or death in the ibrutinib group, 0.22; P<0.001). Ibrutinib also significantly improved overall survival (hazard ratio for death, 0.43; P=0.005). At 12 months, the overall survival rate was 90% in the ibrutinib group and 81% in the ofatumumab group. The overall response rate was significantly higher in the ibrutinib group than in the ofatumumab group (42.6% vs. 4.1%, P<0.001). An additional 20% of ibrutinib-treated patients had a partial response with lymphocytosis. Similar effects were observed regardless of whether patients had a chromosome 17p13.1 deletion or resistance to purine analogues. The most frequent nonhematologic adverse events were diarrhea, fatigue, pyrexia, and nausea in the ibrutinib group and fatigue, infusion-related reactions, and cough in the ofatumumab group.Ibrutinib, as compared with ofatumumab, significantly improved progression-free survival, overall survival, and response rate among patients with previously treated CLL or SLL. (Funded by Pharmacyclics and Janssen; RESONATE ClinicalTrials.gov number, NCT01578707.).
Project description:Rituximab monotherapy has proven efficacy in treatment-naïve, asymptomatic advanced-stage follicular lymphoma (FL). Ofatumumab is a fully humanized anti-CD20 monoclonal antibody with increased CD20 affinity and complement-dependent cytotoxicity. This phase 2 trial (NCT01190449) evaluated ofatumumab in patients with untreated, low/intermediate-risk FL International Prognostic Index (FLIPI), advanced-stage FL to determine single-agent efficacy. Patients with measurable disease in stages III/IV or bulky stage II, regardless of Groupe d'Etude des Lymphomes Folliculaires criteria, received 4 weekly 1000 mg doses followed by four extended induction doses once every 8 weeks. Primary endpoint was overall response rate (ORR) to 1000 mg; secondary endpoints were progression-free survival (PFS) and safety. Fifty-one patients were enrolled. Fifteen patients were randomized to 500 mg prior to discontinuing that arm for slow accrual. Among 36 patients on the 1000 mg arm, ORR was 84%, median PFS was 1·9 years and median response duration was 23·7 months. All patients remain alive. No grade 4 infusion reactions or grade 3/4 infections occurred. Grade 3 infusion reactions occurred in 25% in the 1000 mg arm only (all first infusion); all but two patients continued on study. Discontinuation was 6% for the total study population. Ofatumumab monotherapy administered by extended induction in untreated, low/intermediate-risk FLIPI, advanced-stage FL is well tolerated and active. Activity appears similar to that reported with single-agent rituximab.
Project description:We report the final analysis of the PROLONG study on ofatumumab maintenance in relapsed chronic lymphocytic leukemia (CLL). In all, 480 patients with CLL in complete or partial remission after second- or third-line treatment were randomized 1:1 to ofatumumab (300?mg first week, followed by 1000?mg every 8 weeks for up to 2 years) or observation. Median follow-up duration was 40.9 months. Median progression-free survival was 34.2 and 16.9 months for ofatumumab and observation arms, respectively, (hazard ratio, 0.55 [95% confidence interval, 0.43-0.70]; P?<?0.0001). Median time to next treatment for ofatumumab and observation arms, respectively, was 37.4 and 27.6 months (0.72 [0.57-0.91]; P?=?0.0044). Overall survival was similar in both arms; median was not reached (0.99 [0.72-1.37]). Grade???3 adverse events occurred in 62% and 51% of patients in ofatumumab and observation arms, respectively, the most common being neutropenia (23% and 10%), pneumonia (13% and 12%) and febrile neutropenia (6% and 4%). Up to 60 days after the last treatment, four deaths were reported in the ofatumumab arm versus six in the observation arm, none considered related to ofatumumab. Ofatumumab maintenance significantly prolonged progression-free survival in patients with relapsed CLL and was well tolerated.
Project description:Chronic lymphocytic leukemia (CLL) is an indolent but incurable disease. Despite the improvement of the available therapies, the management of heavily-treated CLL patients represents a challenge for modern practitioners. Ofatumumab is a second-generation, fully human anti-CD20 monoclonal antibody that has shown activity in CLL patients who have failed very effective therapies such as fludarabine, alemtuzumab and rituximab. Potential benefits of ofatumumab include powerful complement-dependent cytotoxicity, less immunogenicity, faster infusions and activity in resistant CLL patients. Recently, the FDA has approved ofatumumab for the treatment of CLL patients who have failed fludarabine and alemtuzumab-based regimens. The aim of this review is to summarize the current knowledge regarding pharmacology, mechanism of action, pre-clinical and clinical development, and the role of ofatumumab for the treatment of CLL patients who have failed previous therapies. Further research is necessary to further define the role of ofatumumab in the treatment of CLL.
Project description:The management of chronic lymphocytic leukemia (CLL) has dramatically improved in the past decade with the addition of anti-CD20 monoclonal antibodies to the treatment armamentarium. Ofatumumab is a novel anti-CD20 monoclonal antibody recently approved in the US and Europe for the treatment of CLL refractory to alemtuzumab and fludarabine. Preclinical data showed improved complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity compared with rituximab. Clinical studies have shown single-agent activity for ofatumumab in CLL and in other low-grade non-Hodgkin's lymphomas. Combination studies are being conducted to enhance the therapeutic efficacy of ofatumumab. This paper reviews some of the key clinical studies that led to approval of ofatumumab, and future directions.
Project description:Ofatumumab is an anti-CD20 antibody recently approved for treatment of fludarabine and alemtuzumab refractory chronic lymphocytic leukemia (CLL); it mediates much stronger complement-dependent cytotoxicity (CDC) than rituximab. Human CD59, a key membrane complement regulator that inhibits CDC, is highly expressed in B-cell malignancies and its upregulation is an important determinant of the sensitivity of B-cell malignancies to rituximab treatment. Previously, we have shown that the potent CD59 inhibitor rILYd4 sensitizes rituximab-resistant lymphoma cells to rituximab-mediated CDC. Here, we further investigated whether rILYd4 can sensitize B-cell malignancies to ofatumumab-mediated CDC and whether either ofatumumab-mediated CDC or rILYd4-enhanced ofatumumab-mediated CDC correlates with CD20 or CD59 expression, known biomarkers involved in rituximab activity.Rituximab-resistant cell lines and primary CLL cells were used to investigate the antitumor efficacy of the combination of rILYd4 with ofatumumab or rituximab. Propidium iodide staining or alamarBlue assay were used to evaluate the CDC effect. The levels of CD20 and CD59 on the cell membrane were analyzed by flow cytometry.rILYd4 enhanced CDC effects mediated by ofatumumab or rituximab on rituximab-resistant lymphoma cells and primary CLL cells in vitro. The sensitivity to CDC effects mediated by ofatumumab positively correlated with the ratio of CD20/CD59 and negatively correlated with CD59 levels on CLL cells. The degree to which rILYd4 enhanced CDC correlated positively with the CD59 levels on CLL cells.These data suggest that rILYd4 may enhance the anticancer activity of ofatumumab and rituximab in B-cell malignancies that have relapsed after prior antibody-based therapies.
Project description:Mantle cell lymphoma (MCL) is a mature B-cell lymphoma considered to be incurable with current treatments, including first-line rituximab in combination with multiagent chemotherapy and for those eligible, high-dose chemotherapy and stem cell support or rituximab maintenance. On the other hand, achieving a complete remission by high-sensitive flow cytometry is associated with prolonged duration of remission, stressing the need to develop and/or incorporate novel agents into the management of MCL. To this end, we examined the activity of ofatumumab, an anti-CD20 monoclonal antibody with distinct binding and immunologic properties compared to rituximab, in MCL preclinical models.MCL cells were labeled with (51)Cr before incubation with rituximab or ofatumumab (10 ?g/mL) plus human serum or effector cells. (51)Cr-release was measured and the percentage of lysis was calculated. Surface CD20, CD55, and CD59 were measured by Imagestream analysis. SCID mice inoculated subcutaneously with Z138 cells were assigned to control versus four doses of ofatumumab or rituximab (10 mg/kg/dose).Ofatumumab exhibited enhanced in vitro complement-dependent cytotoxicity activity compared with rituximab in MCL cell lines, despite a high degree of in vitro resistance to rituximab associated with low CD20 levels and/or high expression of complement inhibitory proteins. Ofatumumab also delayed tumor progression and prolonged survival in a murine model of MCL.Our results demonstrate that ofatumumab is more effective than rituximab in MCL preclinical models, including in the presence of rituximab resistance, and support the clinical investigation of ofatumumab in combination with standard systemic chemotherapy in MCL (NCT01527149).
Project description:Transformation of B-cell chronic lymphocytic leukaemia (B-CLL) to diffuse large B cell lymphoma (DLBCL) (Richter's syndrome (RS)) is a rare (2-15% of patients) but catastrophic complication of B-CLL. Dose-intense chemotherapy regimens investigated in small single institution trials, but with the exception of bone marrow transplantation for a minority of patients, little has improved the median overall survival of patients with RS beyond eight months. Patients are often elderly, immunosuppressed, possess co-morbidities and have a deteriorating performance status. TP53 disruption is a common molecular abnormality noted in RS and contributes to the tumour's chemotherapy resistance. Ofatumumab is a fully human anti-CD20 monoclonal IgG1? antibody that targets a unique epitope on B lymphocytes. It has displayed increased binding affinity and a longer dissociation time when compared to rituximab resulting in improved complement dependent cellular cytotoxicity (CDCC); a mechanism with the potential to overcome apoptosis-resistance in TP53 disruption. Given the prevalence of TP53 disruption in RS, Ofatumumab was considered a relatively non-toxic agent with a sound rationale to test in a prospective multicentre trial as an adjunct to CHOP induction and subsequent ofatumumab maintenance therapy in responding patients.The CHOP-OR study is a prospective phase II study to evaluate the safety, feasibility and activity of a CHOP chemotherapy in combination with ofatumumab in induction and subsequent maintenance for patients with newly diagnosed RS. The primary objective will be the overall response rate (ORR) in patients with RS after six cycles of CHOP-O. The secondary objectives include feasibility of recruitment, progression free survival (PFS), overall survival (OS) and toxicity. The study will be accompanied by exploratory analysis of the genomic landscape of RS in newly diagnosed patients.The CHOP-OR trial evaluates the safety, feasibility and activity of CHOP plus Ofatumumab induction and Ofatumumab maintenance in new RS patients. The study is currently recruiting and has met the interim analysis criteria, with more than 7 of the first 25 participants achieving a CR or PR after six cycles of CHOP-O. The study has the potential to identify predictive biomarkers for this treatment modality.NCT01171378.