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CD205 targeting in lymphomas
Table 1. Prevalence of CD205 expression in hematologic cancers as demonstrated by immunohistochemistry (IHC) on tumor microarrays.
N. of samples
302 82 7 16 13 7 40 3 3
5 2 7 15 5
68 8 7 3
26 14
≥ 1+ (%) 71
73 29 81 31 71 88 0 33
80 50 57 100 100
59 88 86 100
62 100
CD205 expression (IHC)
Lymphoma
B-cell neoplasms
B cell lymphoma (undefined)
Diffuse large B-cell lymphoma
Burkitt’s lymphoma
Follicular lymphoma
Lymphoplasmacytic lymphoma
Mantle cell lymphoma
Mucosa-associated lymphatic tissue lymphoma Small lymphocytic lymphoma
T-cell rich B-cell lymphoma
Hodgkin lymphoma
Hodgkin lymphoma (undefined)
Lymphocyte depleted Hodgkin lymphoma Lymphocyte predominant Hodgkin lymphoma Mixed cellularity
Nodular sclerosis
T-cell and NK-cell neoplasms
T-cell lymphoma (undefined) Anaplastic large cell lymphoma Angioimmunoblastic T-cell lymphoma Peripheral T-cell lymphoma
Leukemia
Acute myeloid leukemia
Myeloma
Multiple myeloma
N: number; NK: natural killer.
2-3+ (%)
37 28 0 23 23 29 50 0 33
20 50 14 7 60
28 50 43 0
58 79
not reduce the anti-tumor activity of the compound (R=- 0.78 and R= -0.72, P<0.001) (Online Supplementary Table S3), as well CD302 itself (R=0.67, P=0.001).
Finally, to further assess the specificity of MEN1309/OBT076, we treated cells with the ADC with or without the addition of MBH-1309, the naked anti- CD205 antibody. The latter molecule had no anti-tumor activity by itself (Online Supplementary Figure S6), but it decreased the activity of MEN1309/OBT076 in a dose dependent manner, as shown both in terms of IC50 and of cell cycle analysis (Figure 1B-D).
MEN1309/OBT076 demonstrates in vivo anti-tumor activity in DLBCL
To confirm the observed in vitro MEN1309/OBT076 anti-lymphoma activity, we performed an in vivo xenograft experiment with the OCI-LY-10 model of DLBCL. Cohorts of mice were treated with vehicle control, IgG- DM4 (5 mg/kg, once every 3 weeks), or MEN1309/OBT076 (1.25, 2.5 or 5 mg/kg once every 3 weeks) (Figure 2A). Low activity was observed with MEN1309/OBT076 1.25 mg/kg (day [D] 7, P=0.012) and with IgG-DM4 (D21, P=0.049; D28, P=0.046). MEN1309/OBT076 at 2.5 mg/kg delayed tumor growth versus control (D21, P=0.039). MEN1309/OBT076 at 5 mg/kg eradicated tumors in all mice with a single dose, highlighted by highly significant differences in tumor vol-
ume versus control mice (D7, D21, D28; P<0.01). Tumor eradication led to an increase in the survival of the mice. While all other groups reached endpoint by D35, the MEN1309/OBT076 5 mg/kg group skipped the second planned treatment at D21 because there was no sign of tumors, and mice remained cured up to two months later (Kaplan-Meier, survival analysis, P<0.0001) (Figure 2B). One mouse belonging to the 5 mg/kg group showed tumor re-growth (D28 and D35), and a second MEN1309/OBT076 injection (D43) conferred tumor remission for the second time (D50 and D57).
MEN1309/OBT076 is synergistic with other targeted agents
MEN1309/OBT076 was then combined with targeted agents in four ABC-DLBCL cell lines (TMD8, HBL1, OCI- LY-10 and U2932) (Table 3). The most effective combina- tions were with the anti-CD20 monoclonal antibody rit- uximab (synergistic in all four), and with the BCL2 inhibitor venetoclax (synergistic in three, additive in one). Both combinations determined increased cell counts as shown by increased percentage of cells in sub-G0 phase during a cell cycle experiment (Online Supplementary Figure S7). Immunoblotting analyses of two ABC-DLBCL cell lines (TMD8 and OCI-LY-10) after exposure to MEN1309/OBT076 provided hints on the mechanism underlining the synergism (Figure 3). Protein levels of anti-
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