Efficacy of ofatumumab against rituximab-resistant B-CLL/SLL cells with low CD20 protein expression

Molecular modeling studies of quinazolinone derivatives as novel PI3Kδ selective inhibitors

The main molecular modeling method, the docking results of newly designed compoundD04and the best pharmacophore model are reported herein.

Clinical utility and patient considerations in the use of ofatumumab in chronic lymphocytic leukemia

Treatment aim for chronic lymphocytic leukemia has been radically changed over the past years from providing only a palliative approach to reaching disease eradication and improving survival. Ofatumumab is a monoclonal humanized antibody with peculiar in vitro and in vivo properties, at present approved for double fludarabine and alemtuzumab refractory chronic lymphocytic leukemia. Its efficacy in this subset of patients, who typically have an unfavorable prognosis, facilitated its use in different Phase II and III trials. Ofatumumab as single agent or combined with chemotherapeutic or biologic agents, led to sundry results in the setting of both previously treated or untreated patients. Its role in maintenance therapy is also under investigation. Further advances concerning ofatumumab administration as first line therapy in combination with chlorambucil, came recently from the COMPLEMENT 1 study. Results from this trial will open the door to new perspectives of its use in treatment-naïve patients. Ofatumumab was well tolerated in almost all the studies, with the main adverse events relating mostly to infusion reaction. Hematologic toxicity, especially neutropenia, was also common. A significant improvement in patients' quality of life was reported following ofatumumab treatment and this was mainly due to its effect on constitutional symptoms. Nevertheless, some concerns remain regarding the long-term efficacy of the drug in terms of response duration and survival. The real strength of this drug needs to be confirmed by further studies and direct comparative trials.

Ofatumumab in combination with glucocorticoids for primary therapy of chronic graft-versus-host disease: phase I trial results

Standard primary therapy for chronic graft-versus-host disease (GVHD) is incompletely effective. Based on biologic insights implicating pathogenic B cells, we conducted a phase I trial examining the combination of standard (1 mg/kg/day prednisone) glucocorticoid therapy with ofatumumab, a humanized anti-CD20 monoclonal antibody, for primary chronic GVHD therapy. Patients ages ≥ 18 with National Institutes of Health Consensus moderate-to-severe chronic GVHD newly requiring 1 mg/kg/day prednisone were treated at 3 escalating dose levels (300 mg, 700 mg, and 1000 mg) of i.v. ofatumumab on days 1 and 14 of initial glucocorticoid therapy. Dose-limiting toxicity (DLT) was defined by grade 4 infusion reactions, related grade 4 constitutional symptoms, related grade ≥ 3 organ toxicities, or grade 4 neutropenia lasting > 14 days. A total of 12 patients (median age 54; range, 25 to 72) were treated (dose level 1: n = 3; level 2: n = 3; level 3: n = 6). At enrollment, overall chronic GVHD was moderate (n = 7) or severe (n = 5), with diverse organ involvement (skin: n = 8; mouth: n = 8; eye: n = 8; lung: n = 4; gastrointestinal: n = 3; liver: n = 5; genital: n = 2; joint/fascia: n = 5). Infusion of ofatumumab was well tolerated, and no DLT was observed. From the total number of adverse events (n = 29), possibly related adverse events (n = 4) included grade 1 fatigue, grade 1 transaminitis, and 2 infusion reactions (grades 2 and 3). Infectious complications were expected, and there were no cases of hepatitis B reactivation or progressive multifocal leukoencephalopathy. Ofatumumab in combination with prednisone is safe and a phase II examination of efficacy is ongoing.

Target antigen density governs the efficacy of anti-CD20-CD28-CD3 ζ chimeric antigen receptor-modified effector CD8+ T cells

The effectiveness of chimeric Ag receptor (CAR)-transduced T (CAR-T) cells has been attributed to supraphysiological signaling through CARs. Second- and later-generation CARs simultaneously transmit costimulatory signals with CD3ζ signals upon ligation, but may lead to severe adverse effects owing to the recognition of minimal Ag expression outside the target tumor. Currently, the threshold target Ag density for CAR-T cell lysis and further activation, including cytokine production, has not yet been investigated in detail. Therefore, we determined the threshold target Ag density required to induce CAR-T cell responses using novel anti-CD20 CAR-T cells with a CD28 intracellular domain and a CD20-transduced CEM cell model. The newly developed CD20CAR-T cells demonstrated Ag-specific lysis and cytokine secretion, which was a reasonable level as a second-generation CAR. For lytic activity, the threshold Ag density was determined to be ∼200 molecules per target cell, whereas the Ag density required for cytokine production of CAR-T cells was ∼10-fold higher, at a few thousand per target cell. CD20CAR-T cells responded efficiently to CD20-downregulated lymphoma and leukemia targets, including rituximab- or ofatumumab-refractory primary chronic lymphocytic leukemia cells. Despite the potential influence of the structure, localization, and binding affinity of the CAR/Ag, the threshold determined may be used for target Ag selection. An Ag density below the threshold may not result in adverse effects, whereas that above the threshold may be sufficient for practical effectiveness. CD20CAR-T cells also demonstrated significant lytic activity against CD20-downregulated tumor cells and may exhibit effectiveness for CD20-positive lymphoid malignancies.

New agents for the treatment of lymphoid leukemia and lymphoma: focus on recent FDA approvals

Leukemia and lymphoma are systemic malignancies that represent half of all childhood cancers, though 90% occur in adults. Various treatment options are available, but therapy is mainly systemic chemotherapy plus appropriate monoclonal antibodies. In certain situations radiotherapy and bone marrow transplantation play a role. Some types/subtypes of these diseases are potentially curable, yet many leukemias and lymphomas do not properly respond to current therapies. Although the FDA (US Food and Drugs Administration) approvals of new drugs have shown a small increasing trend between 2007-2012, overall, the trend of new approvals remains relatively steady between 2006-2013, with a peak of 39 new drugs approved in 2012 and a drop in the new FDA drug approvals in 2013, to 27. Drugs approved for cancer treatment have shown a similar trend. Between 2006-2013, at least one drug was approved every year for the treatment of particular types of lymphoma or leukemia, except in 2010, with a peak of 5 new approvals in 2012. Between January 2013-March 2014, several important new approvals were made: ibrutinib for the treatment of CLL and mantle cell lymphoma (MCL), obinutuzumab for the treatment of CLL (in combination with chlorambucil), and lenalidomide for the treatment of mantle cell lymphoma. The results, importance, adverse effects and mechanisms of action of these agents are discussed in this review. These results held promise and their discovery and approval for the treatment of CLL and MCL is a major step forward. However, the emergence of resistance and the lack of cures need to be addressed by rational development of combination therapy, as well as development of novel drugs with enhanced potency or different mechanism of action, to achieve better overall and complete response rates with decreased toxicity.