Doxorubicin enhances the capacity of B cells to activate T cells in urothelial urinary bladder cancer

Highlights

• Doxorubicin treatment of B cells induces increased expression of CD86.

• B cells treated with doxorubicin, obtain increased APC ability.

• Doxorubicin results in decreased expression of anti-inflammatory cytokines.

• B cells from patients treated with chemotherapy, display increased CD86 expression.

Abstract

Cancer is currently treated by a combination of therapies, including chemotherapy which is believed to suppress the immune system. Combination of immunotherapy and chemotherapy correlates with improved survival but needs careful planning in order to achieve a synergistic effect. In this study, we have demonstrated that doxorubicin treatment of B cells resulted in increased expression of CD86 and concordantly increased CD4⁺ T cell activation in the presence of superantigen, an effect that was inhibited by the addition of a CD86 blocking antibody. Furthermore, doxorubicin resulted in decreased expression of the anti-inflammatory cytokines IL-10 and TNF-α. Finally, B cells from urinary bladder cancer patients, treated with a neoadjuvant regiment containing doxorubicin, displayed increased CD86-expression. We conclude that doxorubicin induces CD86 expression on B cells and hence enhances their antigen-presenting ability in vitro, a finding verified in patients. Development of tailored time and dose schedules may increase the effectiveness of combining chemotherapy and immunotherapy.

Introduction

Muscle-invasive urinary bladder cancer (MIBC) is currently treated by a combination of therapies; including neoadjuvant cisplatin based combination chemotherapy (NAC), cystectomy or radiotherapy. NAC is recommended for cT2-T4aN0M0 MIBC in fit patients [1]. This recommendation is based on a few well designed randomized prospective trials and on the results of the ABC meta-analysis [2], [3], [4].

Chemotherapy is considered to primarily act by cytotoxic effects on tumor cells, accompanied by different side effects, including suppression of the host immune system [5]. Some studies however, indicate that chemotherapeutic drugs increase the anti-tumoral immune response and cause tumor regression [6], [7]. It is hypothesized that a dense lymphocytic infiltrate is a positive prognostic factor for survival in different types of cancer [8], [9], [10]. Additionally, it has been shown that treatment with chemotherapy confers improved prognosis in the presence of tumor infiltrating lymphocytes (TILs) [11]. In a study with 1058 breast cancer patients, a pathological complete remission (pCR) was observed primarily in tumors with increased lymphocytic infiltrate. Tumors with > 60% stromal or intratumoral lymphocytes had a pCR rate of 41.7%, whereas tumors without TILs had a pCR rate of only 2.8% [11]. In MIBC, the results of a post-hoc evaluation of the Nordic randomized trials 1 & 2 displayed that patients with pCR (pT0N0M0) had the highest 5-year survival with an absolute risk reduction (ARR) of 31% [12]. Immunotherapy is an additional approach in treating cancer patients. It may offer fewer side effects than conventional treatments and provide long-lasting immunological memory which can respond to possible future tumor relapses. Novel immune-based treatments include monoclonal antibodies and adoptive autologous lymphocyte transfer [13], [14], [15].

B cells are important contributors of an anti-tumoral immune response, by presenting tumor antigens to T cells [16] and producing tumor-specific antibodies [17]. B cells can upon stimulation with IL-21, also secrete granzyme B [18] which has direct cytotoxic effects. In addition, by producing different cytokines and chemokines, B cells can regulate other immune cells, e.g. by assisting the formation of CD4⁺ memory T cells [19] and promote survival and proliferation of CD8⁺ T cells [20]. Furthermore, tumor infiltrating B cells (TIL-B) comprise a significant component of lymphocytic infiltrates in tumors. TIL-B have been correlated with survival in ovarian cancer where CD8⁺ and CD20⁺ tumor infiltrating lymphocytes (TILs) were analyzed using immunohistochemistry and flow cytometry. The presence of both CD8⁺ and CD20⁺ TIL correlated with increased patient survival, as compared with the presence of either of the TIL alone, suggesting synergism between the two [9].

Patients receiving both immunotherapy and chemotherapy have been reported to exhibit prolonged time to progression and improvement of survival, compared to patients receiving chemotherapy alone [21]. However, the combination of cytotoxic drugs and immunotherapy may need careful planning, in order to reach synergistic effects. Ideally, chemo-immunotherapy treatments should initially be evaluated for their effects on the immune system. Based on such studies, drug dosing and time schedules, allowing for recovery of immune function, can be developed, which may lead to improved anti-tumor responses.

Thus, the effects of chemotherapeutic drugs on different T cell subsets in the immune system need further investigations. We have previously studied the effect of three conventional chemotherapeutic drugs; doxorubicin, cisplatin and irinotecan, on human monocytes and dendritic cells (DCs) [6]. Cisplatin treatment enhanced the immune stimulatory ability of human monocytes, a mechanism mediated mainly by the increased production of interferon (IFN)-β. This project aims to investigate the effect of chemotherapeutic drugs on human B cells and their effect on their function as antigen presenting cells (APCs).