Classic Hodgkin lymphoma (cHL) responds markedly to PD-1 blockade therapy, and the clinical responses are reportedly dependent on expression of major histocompatibility complex class II (MHC-II). This dependence is different from other solid tumors, in which the MHC class I (MHC-I)/CD8+ T-cell axis plays a critical role. In this study, we investigated the role of the MHC-II/CD4+ T-cell axis in the antitumor effect of PD-1 blockade on cHL. In cHL, MHC-I expression was frequently lost, but MHC-II expression was maintained. CD4+ T cells highly infiltrated the tumor microenvironment of MHC-II–expressing cHL, regardless of MHC-I expression status. Consequently, CD4+ T-cell, but not CD8+ T-cell, infiltration was a good prognostic factor in cHL, and PD-1 blockade showed antitumor efficacy against MHC-II–expressing cHL associated with CD4+ T-cell infiltration. Murine lymphoma and solid tumor models revealed the critical role of antitumor effects mediated by CD4+ T cells: an anti-PD-1 monoclonal antibody exerted antitumor effects on MHC-I−MHC-II+ tumors but not on MHC-I−MHC-II− tumors, in a cytotoxic CD4+ T-cell–dependent manner. Furthermore, LAG-3, which reportedly binds to MHC-II, was highly expressed by tumor-infiltrating CD4+ T cells in MHC-II–expressing tumors. Therefore, the combination of LAG-3 blockade with PD-1 blockade showed a far stronger antitumor immunity compared with either treatment alone. We propose that PD-1 blockade therapies have antitumor effects on MHC-II–expressing tumors such as cHL that are mediated by cytotoxic CD4+ T cells and that LAG-3 could be a candidate for combination therapy with PD-1 blockade.

Histiocytic sarcoma (HS) is an extremely rare malignant neoplasm that often exhibits an aggressive clinical presentation. In this report, we describe the case of a 38-year-old female with advanced-stage HS who was found to have a subcutaneous tumor in the left calf and enlarged lymph nodes in the left inguinal and internal iliac regions. The subcutaneous tumor and inguinal nodes were resected operatively. Immunohistochemistry of the surgical specimens showed that the malignant cells stained positive for CD163, CD68, and related markers; a diagnosis of HS was established. Following the administration of induction chemotherapy consisting of dose-escalated CHOP plus etoposide, the remaining internal iliac tumors disappeared. At that point, high-dose chemotherapy with autologous stem cell transplantation was performed as consolidation treatment. The patient remains alive with no evidence of disease for 30 months post-treatment. This report provides valuable insight into the treatment of advanced HS.

For patients who have chronic myeloid leukemia (CML), one of the primary treatment options is administration of nilotinib 300 mg twice daily (BID). In previous studies which compared outcomes associated with nilotinib or imatinib treatment, nilotinib achieved a higher rate of deep molecular response (MR). We conducted a phase II, open-label, multicenter study to investigate an intrapatient nilotinib doseescalation strategy for patients with newly diagnosed chronic-phase (CP) CML based on early MR 4.5 achievement. The primary study endpoint was achievement of MR 4.5Note: Data are presented as n (%) or median (range).Abbreviations: CML, chronic myelogenous leukemia; EUTOS, European Treatment and Outcome Study; HU, hydroxyurea.

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Allo-HSCT may not be required in the pediatric regimen-eligible patients; however, pediatric regimen-ineligible patients with either CD20 positivity or high WBC count should receive allo-HSCT after achieving 1CR. This study was registered at http://www.umin.ac.jp/ctr/ as #C000016287.