KIR/HLA Interactions Negatively Affect Rituximab- but Not GA101 (Obinutuzumab)-Induced Antibody-Dependent Cellular Cytotoxicity

Abstract

Ab-dependent cellular cytotoxicity (ADCC) mediated by NK cells is regulated by inhibitory killer cell Ig–like receptors (KIRs), which interact with target cell HLA class I. We analyzed how KIR/HLA interactions influence ADCC induced by rituximab and by GA101, a novel type II CD20 Ab glycoengineered for increased FcgRIII binding and ADCC capacity. We found that KIR/HLA interactions strongly and selectively inhibit rituximab-induced in vitro ADCC toward target cells expressing cognate HLA KIR ligands. NK cells of donors carrying all three ligands to inhibitory KIR showed weak activation and target cell depletion capacity when incubated with rituximab and KIR-ligand matched target B cells. In contrast, NK cells from individuals missing one or more KIR ligands activated more strongly and depleted KIR ligand–matched target B cells more efficiently in the presence of rituximab. NK cells expressing a KIR for which the ligand was absent were the main effectors of ADCC in these donors. Notably, the influence of KIR/HLA interactions on NK cell activation was synergistic with the effect of the V158F FCGR3A single nucleotide polymorphism. In contrast, GA101 induced activation of NK cells irrespective of inhibitory KIR expression, and efficiency of target cell depletion was not negatively affected by KIR/HLA interactions. These data show that modification of the Fc fragment to enhance ADCC can be an effective strategy to augment the efficacy of therapeutic mAbs by recruiting NK cells irrespective of their inhibitory KIR expression.

How to outsmart NK cell tolerance

“…Importantly, multiple KIR/HLA interactions were necessary to decrease obinutuzumabinduced ADCC to the level achieved by rituximab. 2 In line with these observations, target depletion was unaffected by both the percentage of unlicensed effector cells in the repertoire, and by the number of KIR ligands expressed on target cells. In summary, obinutuzumab can induce comparable percentage and quality of activation in all NK cells subpopulations, independent from the licensing status and the KIR/HLA interactions (Fig.…”

“…1A). 2 In line with the concept of unlicensed NK cells being the strongest ADCC effector cells, we observed that killing efficiency correlated positively with the percentage of unlicensed cells. Considering that in Caucasians approximately 30 percent of individuals carry all HLA ligands to the 3 relevant inhibitory KIR receptors (KIR2DL1, KIR2DL2/3, and KIR3DL1), the benefit of anti-CD20 therapy in such patients may be strongly limited by NK cell tolerance.…”

Neuroblastoma patients with high-affinity FCGR2A, -3A and stimulatory KIR 2DS2 treated by long-term infusion of anti-GD2 antibody ch14.18/CHO show higher ADCC levels and improved event-free survival

“…We limited our analysis to 2DL1-3 and 3DL1 based on the recently reported involvement of these KIRs on efficacy of Ab-dependent immunotherapy. 7,28 Due to lack of expression on effector cells, we excluded the remaining known KIR pseudogenes 2DP1and 3DP1 from our analysis. 29 For analysis of KIRLs HLA-C1, HLA-C2 and HLA-Bw4, DNA samples of 52 NB patients were available.…”

“…Following treatment protocol was used: cytokine IL-2 was given for 5 d (s.c., day 1-5, 6 £ 10 6 IU/m 2 /day), followed by a combined application of IL-2 (s.c., day 8-12, 6 £ 10 6 IU/m 2 / day) with ch14.18/CHO (i.v., day 8-18, 10 mg/m 2 /day) and 13-cis-retinoic acid (p.o., day [22][23][24][25][26][27][28][29][30][31][32][33][34][35]. At initial diagnosis, 46 patients had stage 4, four stage 3, one stage 2 and two stage 1 disease.…”

Targeting CD20 in chronic lymphocytic leukemia

“…43 In particular, obinutuzumab has a 50-fold higher affinity for the FcgRIIIa region and 100-fold greater ADCC than rituximab. 43,49 It also has no CD20 antigen internalization with binding, and thus no shaving/trogocytosis in contrast to rituximab. 43 The CLL 11 study conducted by the GCLLSG was recently published in the New England Journal of Medicine (NEJM).…”