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- Stasiłojć, Grzegorz, et al.
(författare)
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Calcein release assay as a method for monitoring serum complement activity during monoclonal antibody therapy in patients with B-cell malignancies
- 2020
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Ingår i: Journal of Immunological Methods. - : Elsevier BV. - 0022-1759 .- 1872-7905. ; 476, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- Monoclonal antibodies ofatumumab (anti-CD20) and alemtuzumab (anti-CD52) which are approved for usage in patients with chronic lymphocytic leukemia (CLL), efficiently activate the classical complement pathway. However complement is an exhaustible component and high doses of its activators may deplete complement-dependent cytotoxicity (CDC) potential, thus reducing the effect of repeated mAb dosing. Widely used method to measure CDC activity of patients' serum is hemolytic assay (CH50) on sheep erythrocytes. Despite its simplicity, such CH50 assay may not reflect pivotal interactions between patient serum and human complement inhibitors on the surface of target cells. We propose calcein release assay performed on tumor cells similar to those targeted by therapeutic antibodies as an alternative method. We analyzed serum samples collected from 12 patients participating in the clinical study, receiving s.c. 30 mg alemtuzumab three times per week combined with i.v. ofatumumab at an initial dose of 300 mg in week 3 further escalated to 2000 mg every other week. All serum samples were measured by hemolytic assay on sheep erythrocytes as well as using calcein release assay on CD20-positive Raji cells. Our data show that results obtained from both assays are related to each other at the level of the whole group (n = 96 samples, Spearman r = 0.504, p < .001) but may substantially differ when analyzing individual patients. Furthermore, by using CDC assay on Raji cells, we found that in the presented clinical study CDC serum potential was not significantly affected when measured before consecutive administrations in most of the patients.
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| 2. |
- Stasiłojć, Grzegorz, et al.
(författare)
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New perspectives on complement mediated immunotherapy
- 2016
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Ingår i: Cancer Treatment Reviews. - : Elsevier BV. - 0305-7372 .- 1532-1967. ; 45, s. 68-75
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Forskningsöversikt (refereegranskat)abstract
- Tumor-specific monoclonal antibodies (mAbs) offer several modes of tumor cell killing, from direct cytotoxic activity to indirect mechanisms employing the host immune system, particularly its innate branch. The latter effector functions seem to dominate among clinically approved anti-cancer mAbs and major efforts are being undertaken by both academia and the pharmaceutical industry with the aim to improve complement activation, antibody-dependent cellular cytotoxicity (ADCC) and Fc/opsonin-mediated phagocytosis. On one hand, there are a variety of available effector mechanisms to allow multistep elimination of tumor cells. On the other hand, tumor cells adopt a number of strategies to evade immune attack, such as overexpression of complement inhibitors, trogocytosis, shedding or internalization of mAb-targeted epitopes, which all contribute to their resistance against host defense mechanisms. Another problem recognized only recently is the depletion of immune effectors during the first round of treatment, which in concordance with delayed turnover of immune components renders subsequent rounds of therapy ineffective. Herein, we discuss newly identified limiting factors but also novel mechanistic data on complement activation by antitumor antibodies as issues important for guidance towards the next generations of immunotherapeutics.
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