Treatment of mantle cell lymphoma: targeting the microenvironment

The four types of Tregs in malignant lymphomas

Regulatory T cells (Tregs) are a specialized subpopulation of CD4⁺ T cells, which act to suppress the activation of other immune cells. Tregs represent important modulators for the interaction between lymphomas and host microenvironment. Lymphomas are a group of serious and frequently fatal malignant diseases of lymphocytes. Recent studies revealed that some lymphoma T cells might adopt a Treg profile. Assessment of Treg phenotypes and genotypes in patients may offer prediction of outcome in many types of lymphomas including diffuse large B-cell lymphoma, follicular lymphoma, cutaneous T cell lymphoma, and Hodgkin's lymphoma. Based on characterized roles of Tregs in lymphomas, we can categorize the various roles into four groups: (a) suppressor Tregs; (b) malignant Tregs; (c) direct tumor-killing Tregs; and (d) incompetent Tregs. The classification into four groups is significant in predicting prognosis and designing Tregs-based immunotherapies for treating lymphomas. In patients with lymphomas where Tregs serve either as suppressor Tregs or malignant Tregs, anti-tumor cytotoxicity is suppressed thus decreased numbers of Tregs are associated with a good prognosis. In contrast, in patients with lymphomas where Tregs serve as tumor-killing Tregs and incompetent Tregs, anti-tumor cytotoxicity is enhanced or anti-autoimmune Tregs activities are weakened thus increased numbers of Tregs are associated with a good prognosis and reduced numbers of Tregs are associated with a poor prognosis. However, the mechanisms underlying the various roles of Tregs in patients with lymphomas remain unknown. Therefore, further research is needed in this regard as well as the utility of Tregs as prognostic factors and therapy strategies in different lymphomas.

Granulomatous slack skin presenting as acquired ichthyosis and muscle masses

We describe a case of granulomatous slack skin in a 31-year-old woman with an unusual presentation of acquired ichthyosis and muscular masses involving four limbs over 3 years. Vesicles and ulcerative skin nodules first appeared only 3 months prior to diagnosis. The diagnosis was confirmed after sequential biopsies of muscle, skin lesions, and lymph nodes, together with molecular genetic studies. The patient responded poorly to various therapies, including thalidomide, and died of doxorubicin-related cardiomyopathy.

Long-term results of the treatment of patients with mantle cell lymphoma with cladribine (2-CDA) alone (95-80-53) or 2-CDA and rituximab (N0189) in the North Central Cancer Treatment Group

BACKGROUND

The objective of this study was to test cladribine (2-CDA) alone and in combination with rituximab in patients with mantle cell lymphoma (MCL).

METHODS

Patients with MCL were treated on 2 sequential trials. In Trial 95-80-53, patients received 2-CDA as initial therapy or at relapse. In Trial N0189, patients received combination 2-CDA and rituximab as initial therapy. In both trials, 2-CDA was administered at a dose of 5 mg/m2 intravenously on Days 1 through 5 every 4 weeks for 2 to 6 cycles, depending on response. In Trial N0189, rituximab 375 mg/m2 was administered on Day 1 of each cycle.

RESULTS

Results were reported for 80 patients. Twenty-six previously untreated patients and 25 patients who had recurrent disease with a median age of 68 years received single-agent 2-CDA. The overall response rate (ORR) was 81% with 42% complete responses (CRs) in the previously untreated group. The median progression-free survival (PFS) was 13.6 months (95% confidence interval [95% CI], 7.2-22.1 months), and 81% of patients remained alive at 2 years. The ORR was 46% with a 21% CR rate in the recurrent disease group. The median PFS was 5.4 months (95% CI, 4.6-13.1 months), and 36% of patients remained alive at 2 years. Twenty-nine eligible patients with a median age of 70 years received 2-CDA plus rituximab. The ORR was 66% (19 of 29 patient), and the CR rate was 52% (15 of 29 patients). The median duration of response for patients who achieved a CR had not been reached at the time of the current report, and only 3 of the patients who achieved a CR developed recurrent disease at a median follow-up of 21.5 months.

CONCLUSIONS

2-CDA had substantial single-agent activity in both recurrent and untreated MCL, and the results indicated that it may be administered safely to elderly patients. The addition of rituximab to 2-CDA may increase the duration of response.

Local and systemic induction of CD4+CD25+ regulatory T-cell population by non-Hodgkin lymphoma

Regulatory T (Treg) cells contribute to immune evasion by malignancies. To investigate their importance in non-Hodgkin lymphoma (NHL), we enumerated Treg cells in peripheral blood mononuclear cells (PBMCs) and involved tissues from 30 patients. CD25(+)FoxP3(+)CD127(low)CD4(+) Treg cells were increased markedly in PBMCs (median = 20.4% CD4 T cells, n = 20) versus healthy controls (median = 3.2%, n = 13, P < .001) regardless of lymphoma subtype, and correlated with disease stage and serum lactate dehydrogenase (R(s) = 0.79, P < .001). T-cell hyporesponsiveness was reversed by depleting CD25(+) cells, or by adding anti-CTLA-4, supporting the view that Treg cells explain the systemic immunosuppression seen in NHL. A high proportion of Treg cells was also present in involved tissues (median = 38.8% CD4 T cells, n = 15) versus reactive nodes (median = 11.6%, n = 2, P = .02). When autologous CD25(-) PBMC fractions were incubated with tumor cells from patients (n = 6) in vitro, there was consistent strong induction and then expansion of cells with the CD4(+)CD25(+)FoxP3(+) phenotype of classic "natural" Treg cells. This population was confirmed to be suppressive in function. Direct cell-cell interaction of tumor cells with CD25(-) PBMCs was important in Treg induction, although there was heterogeneity in the mechanisms responsible. We conclude that NHL cells are powerful inducers of Treg cells, which may represent a new therapeutic target.

Intratumoral CD4+CD25+ regulatory T-cell-mediated suppression of infiltrating CD4+ T cells in B-cell non-Hodgkin lymphoma

Most non-Hodgkin lymphomas (NHLs) are of B-cell origin, but the tumor tissue can be variably infiltrated with T cells. In the present study, we have identified a subset of CD4(+)CD25(+) T cells with high levels of CTLA-4 and Foxp3 (intratumoral T(reg) cells) that are overrepresented in biopsy specimens of B-cell NHL (median of 17% in lymphoma biopsies, 12% in inflammatory tonsil, and 6% in tumor-free lymph nodes; P = .001). We found that these CD4(+)CD25(+) T cells suppressed the proliferation and cytokine (IFN-gamma and IL-4) production of infiltrating CD4(+)CD25(-) T cells in response to PHA stimulation. PD-1 was found to be constitutively and exclusively expressed on a subset of infiltrating CD4(+)CD25(-) T cells, and B7-H1 could be induced on intratumoral CD4(+)CD25(+) T cells in B-cell NHL. Anti-B7-H1 antibody or PD-1 fusion protein partly restored the proliferation of infiltrating CD4(+)CD25(-) T cells when cocultured with intratumoral T(reg) cells. Finally, we found that CCL22 secreted by lymphoma B cells is involved in the chemotaxis and migration of intratumoral T(reg) cells that express CCR4, but not CCR8. Taken together, our results suggest that T(reg) cells are highly represented in the area of B-cell NHL and that malignant B cells are involved in the recruitment of these cells into the area of lymphoma.