Lenalidomide-induced upregulation of CD80 on tumor cells correlates with T-cell activation, the rapid onset of a cytokine release syndrome and leukemic cell clearance in chronic lymphocytic leukemia

Abstract

Background: In chronic lymphocytic leukemia lenalidomide causes striking immune activation, possibly leading to clearance of tumor cells. We conducted this study to investigate the mechanism of action of lenalidomide and the basis for its unique toxicities in chronic lymphocytic leukemia.

Design and methods: Patients with relapsed chronic lymphocytic leukemia were treated with lenalidomide 20 mg (n=10) or 10 mg (n=8) daily for 3 weeks on a 6-week cycle. Correlative studies assessed expression of co-stimulatory molecules on tumor cells, T-cell activation, cytokine levels, and changes in lymphocyte subsets.

Results: Lenalidomide upregulated the co-stimulatory molecule CD80 on chronic lymphocytic leukemia and mantle cell lymphoma cells but not on normal peripheral blood B cells in vitro. T-cell activation was apparent in chronic lymphocytic leukemia, weak in mantle cell lymphoma, but absent in normal peripheral blood mononuclear cells and correlated with the upregulation of CD80 on B cells. Strong CD80 upregulation and T-cell activation predicted more severe side effects, manifesting in 83% of patients as a cytokine release syndrome within 8-72 h after the first dose of lenalidomide. Serum levels of various cytokines, including tumor necrosis factor-alpha, increased during treatment. CD80 upregulation on tumor cells correlated with rapid clearance of leukemic cells from the peripheral blood. In contrast, neither the severity of the cytokine release syndrome nor the degree of T-cell activation in vitro correlated with clinical response.

Conclusions: Upregulation of CD80 on tumor cells and T-cell activation correlate with unique toxicities of lenalidomide in chronic lymphocytic leukemia. However, T-cell activation appears to be dispensable for the drug's anti-tumor effects. This provides a rationale for combinations of lenalidomide with fludarabine or alemtuzumab.

Figure 1.

Upregulation of co-stimulatory molecules and T-cell activation. Upregulation of CD80, CD86 and CD95 on malignant B cells from patients with CLL, MCL and on normal B cells with (A) lenalidomide or (B) CpG. CD69 upregulation on T cells in the same samples: (C) lenalidomide, (D) CpG. (E) correlation between B-cell and T-cell responses to lenalidomide: CLL (open squares), MCL (gray diamond), normal donors (black triangles).

Figure 2.

Cytokine release in CLL patients treated with lenalidomide: (A) daily after the initiation of lenalidomide in patient L13 and (B) in patients pre-treatment (squares, n=13), on day 4 (triangle, n=4) and on day 8 (diamonds, n=13) of lenalidomide treatment. (C) CRP serum levels. (D) Correlation of CRP (maximal value week 1) and cytokine release score.

Figure 3.

Effect of lenalidomide on lymphocytes: (A) percent change compared to pre-treatment cycle 1 day 8. Patient 11: no data. (B) Mean and standard deviation of cell counts. (C) CD3 T-cell content in lymph node biopsies pre-treatment (white columns) and on day 8 of cycle 1 (black columns). (D) CD3 staining in lymph node core biopsies.

Figure 4.

Pearson’s correlation between the upregulation of cell surface markers in response to lenalidomide in vitro and clinical outcome: (A) for the cytokine release score (n=17), and (B) for peripheral blood response of patients measured as reduction in B-cell count on day 21 compared to pre-treatment (n=10).