Langerhans Cell Histiocytosis: A Population-based Study of Anatomical Distribution and Treatment Patterns.

Background: Langerhans cell histiocytosis (LCH) is a rare monoclonal histiocytic neoplasm. Little is known about clinical factors associated with LCH single- vs multi-system involvement at the time of diagnosis. Methods: Data on 1549 LCH patients diagnosed between years 2010 and 2018 were extracted from the Surveillance, Epidemiology and End Results Program. Patterns of single- vs multisystem involvement were examined using multivariable logistic regression analysis. Odd ratio (OR) and 95% confidence interval (CI) were reported. Results: 968 children and adolescents (0-19 years; median: 4 years) and 581 adults (≥20 years; median: 49 years) were included in the analysis. Multi-system LCH was reported for 30.9 % patients. Bone marrow (BM) (OR = 3.776; 95 %CI = 1.939-7.351; P < 0.001) and lymph node (LN) (OR = 3.274; 95 %CI = 1.443-7.427; P = 0.005) involvement were most commonly associated with multi-system LCH at the time of diagnosis; similar pattern was also observed in adult patients (OR = 17.780; 95 %CI = 6.469-48.867; P < 0.001 for BM LCH; and OR = 5.156; 95 %CI = 2.131-12.471; P < 0.001 for LN LCH). Among pediatric patients, craniofacial osseous LCH was more likely to be treated with surgery (OR = 2.822; 95 %CI = 1.199-6.639; P = 0.018) compared to skeletal lesions in other sites, whereas vertebral body LCH was less likely to be treated with surgery (OR = 0.175; 95 %CI = 0.058-0.527; P = 0.002). In pediatric patients with bone LCH, the non-white patients were less likely to be treated surgically compared to the white patients (OR = 0.470; 95 %CI = 0.272-0.812; P = 0.007). Conclusions: BM and LN LCH are associated with the highest risks of multi-system disease, which may require active surveillance. Furthermore, active attempts are needed to mitigate the racial disparity in surgery utilization in pediatric patients with skeletal LCH.

Durable remission for four pediatric patients with high-risk relapsed classical Hodgkin lymphoma treated with brentuximab vedotin plus gemcitabine but without autologous stem cell transplantation: A report from the Children's Oncology Group.

Patients with therapy-refractory or high-risk relapsed classical Hodgkin lymphoma are typically treated with the high-dose chemotherapy and autologous stem cell transplantation (HDC/ASCT) to consolidate the response to salvage therapy. The combination of brentuximab vedotin with gemcitabine has recently been shown to be an effective and safe salvage regimen. While the majority of patients with complete responses to this regimen ultimately underwent HDC/ASCT consolidation, four subjects, reported herein, achieved durable complete remissions lasting more than 4 years after the study treatment but without ASCT consolidation. Further investigation of treatment strategies incorporating targeted agents may allow omission of HDC/ASCT for select patients.

Incidence, Clinical Features, and Outcomes of Langerhans Cell Histiocytosis in the United States.

Langerhans cell histiocytosis (LCH) is a disorder with highly diverse clinical manifestations. We explored if age, sex, race, organ system involved, and therapy approaches determine patient survival in the era of modern treatments. LCH patient data reported to the Surveillance, Epidemiology, and End Results (SEER) program in 2010-2016 (n=1282; age: 0 to 100 y) was analyzed. Age-specific LCH incidence flattening to a low level suggests an age cutoff for pediatric patients of 20 years. The overall survival probability is lower for patients 21 to 100 years old ( P <0.0001), irrespective of sex and race. The commonest sites involved in the 0- to 20-year age group were bone, skin, and bone marrow; this shifted to lung, bone, and skin as the commonest disease sites in patients 21 to 100 years of age. The treatments applied differed between age groups, as younger versus older patients were more likely to receive chemotherapy-based treatment (48.4% vs. 17%; P <0.0001). There also was a trend toward nonwhite versus white patients being less likely to receive chemotherapy-based treatment (31.7% vs. 38.2%; P =0.067). Whereas there are treatment disparities related to LCH patient age and perhaps race, patient age is the strongest predictor of survival, with patients 21 to 100 years of age with lung, lymph node, skin, and bone marrow disease having the worst outcomes ( P <0.0001).

A Case of Subacute Brain Hemorrhage and Disseminated Intravascular Coagulation Secondary to Acute Promyelocytic Leukemia in a Pediatric Patient.

Acute promyelocytic leukemia (APML), characterized by the reciprocal translocation between chromosomes 15 and 17 [t(15;17)], is a result of proliferation of myeloid cells maturation which is interrupted at the promyelocytic stage. The central, and the most important, distinguishing feature of APML is a predisposition to disseminated intravascular coagulation (DIC). The overall prognosis of APML is very good, with 90% of patients achieving complete remission. We find it important to remind pediatric practitioners, both in the ambulatory and urgent care room settings, of presenting signs and symptoms of leukemia, as well as, up-to-date on management of such fulminant scenarios as DIC. Intracranial hemorrhage (ICH) is one of the commonest, and frequently fulminant complication of APML seen after initiation of induction chemotherapy. We report on a young female presenting with non-specific upper respiratory illness symptoms and recurrent headache, who was found to already have ICH and to be in DIC in the setting of APML at the time of initial evaluation. This case illustrates importance of thorough assessment and prompt consideration of wide differential diagnosis, which became somewhat limited and biased towards web-based telemedicine in the COVID-19 pandemics era.

A novel multimeric IL15/IL15Rα-Fc complex to enhance cancer immunotherapy.

The role of T cells in controlling human cancers is well known. Their success requires continued persistence in vivo and efficient trafficking to tumor sites, requirements shared by other effectors such as Natural Killer (NK) cells. To date, cytokine IL2 remains the only clinically approved cytokine therapy available to expand, maintain, and activate these effector lymphoid cells, but toxicities can be severe. Cytokine IL15 offers similar T cell proliferation and activation properties, but without the unwanted side-effects seen with IL2. Several IL15-cytokine fusion proteins have been developed to improve their in vivo function, typically exploiting the IL15Rα to complex with IL15, to extend serum half-life and increase affinity for IL15ß receptor on immune cells. Here we describe a novel IL15 complex incorporating the full-length IL15Rα to complex with wild type IL15 to form spontaneous trimers of dimers (6 IL15 + 6 IL15Rα) during co-expression, resulting in a substantial increase in serum half-life and enhancement of in vivo cytokine effect on IgG or T cell engaging antibody-dependent cell-mediated cytotoxicities, when compared to alternative strategies.

Ab-IL2 fusion proteins mediate NK cell immune synapse formation by polarizing CD25 to the target cell-effector cell interface.

The huKS-IL2 immunocytokine (IC) consists of IL2 fused to a mAb against EpCAM, while the hu14.18-IL2 IC recognizes the GD2 disialoganglioside. They are under evaluation for treatment of EpCAM(+) (ovarian) and GD2(+) (neuroblastoma and melanoma) malignancies because of their proven ability to enhance tumor cell killing by antibody-dependent cell-mediated cytotoxicity (ADCC) and by antitumor cytotoxic T cells. Here, we demonstrate that huKS-IL2 and hu14.18-IL2 bind to tumor cells via their antibody components and increase adhesion and activating immune synapse (AIS) formation with NK cells by engaging the immune cells' IL-2 receptors (IL2R). The NK leukemia cell line, NKL (which expresses high affinity IL2Rs), shows fivefold increase in binding to tumor targets when treated with IC compared to matching controls. This increase in binding is effectively inhibited by blocking antibodies against CD25, the α-chain of the IL2R. NK cells isolated from the peritoneal environment of ovarian cancer patients, known to be impaired in mediating ADCC, bind to huKS-IL2 via CD25. The increased binding between tumor and effector cells via ICs is due to the formation of AIS that are characterized by the simultaneous polarization of LFA-1, CD2 and F-actin at the cellular interface. AIS formation of peritoneal NK and NKL cells is inhibited by anti-CD25 blocking antibody and is 50-200% higher with IC versus the parent antibody. These findings demonstrate that the IL-2 component of the IC allows IL2Rs to function not only as receptors for this cytokine but also as facilitators of peritoneal NK cell binding to IC-coated tumor cells.

Differential internalization of hu14.18-IL2 immunocytokine by NK and tumor cell: impact on conjugation, cytotoxicity, and targeting.

The hu14.18-IL2 (EMD 273063) IC, consisting of a GD(2)-specific mAb genetically engineered to two molecules of IL-2, is in clinical trials for treatment of GD(2)-expressing tumors. Anti-tumor activity of IC in vivo and in vitro involves NK cells. We studied the kinetics of retention of IC on the surface of human CD25(+)CD16(-) NK cell lines (NKL and RL12) and GD(2)(+) M21 melanoma after IC binding to the cells via IL-2R and GD(2), respectively. For NK cells, ∼ 50% of IC was internalized by 3 h and ∼ 90% by 24 h of cell culture. The decrease of surface IC levels on NK cells correlated with the loss of their ability to bind to tumor cells and mediate antibody-dependent cellular cytotoxicity in vitro. Unlike NK cells, M21 cells retained ∼ 70% of IC on the surface following 24 h of culture and maintained the ability to become conjugated and lysed by NK cells. When NKL cells were injected into M21-bearing SCID mice, IT delivery of IC augmented NK cell migration into the tumor. These studies demonstrate that once IC binds to the tumor, it is present on the tumor surface for a prolonged time, inducing the recruitment of NK cells to the tumor site, followed by tumor cell killing.

Enhanced T-cell-independent antitumor effect of cyclophosphamide combined with anti-CD40 mAb and CpG in mice.

We have earlier demonstrated T-cell-independent antitumor effects of a combination of anti-CD40 monoclonal antibody (mAb) and CpG oligodeoxynucleotides (CpG) which involved macrophages. As some immunotherapeutic treatments can be potentiated by chemotherapy, we tested if cyclophosphamide (CY) would enhance the antitumor effect of anti-CD40 mAb+CpG. Treatment of B16 melanoma-bearing mice with CY and anti-CD40 mAb+CpG resulted in a significant reduction in tumor growth in immunocompetent mice compared with either CY alone or anti-CD40 mAb with CpG. This enhanced antitumor effect was maintained in severe combined immunodeficiency mice, as measured by both tumor growth and overall survival. Natural killer cells were not required for this antitumor effect as it was also observed in severe combined immunodeficiency/beige mice. Moreover, although CY treatment of immunocompetent mice suppressed natural killer cell activity, it did not negatively affect the antitumor activity of their macrophages when assayed in vitro. Depletion of macrophages in vivo reduced the antitumor effect of CY and anti-CD40 mAb+CpG. These results suggest that therapeutic strategies to activate macrophages may have potential for clinical application in cancer patients receiving chemotherapy.

Anti-tumour synergy of cytotoxic chemotherapy and anti-CD40 plus CpG-ODN immunotherapy through repolarization of tumour-associated macrophages.

We studied the effectiveness of monoclonal anti-CD40 + cytosine-phosphate-guanosine-containing oligodeoxynucleotide 1826 (CpG-ODN) immunotherapy (IT) in mice treated with multidrug chemotherapy (CT) consisting of vincristine, cyclophosphamide and doxorubicin. Combining CT with IT led to synergistic anti-tumour effects in C57BL/6 mice with established B16 melanoma or 9464D neuroblastoma. CT suppressed the functions of T cells and natural killer (NK) cells, but primed naïve peritoneal macrophages (Mφ) to in vitro stimulation with lipopolysaccharide (LPS), resulting in augmented nitric oxide (NO) production. IT, given after CT, did not restore the responsiveness of T cells and NK cells, but further activated Mφ to secrete NO, interferon-γ (IFN-γ) and interleukin (IL)-12p40 and to suppress the proliferation of tumour cells in vitro. These functional changes were accompanied by immunophenotype alterations on Mφ, including the up-regulation of Gr-1. CD11b(+) F4/80(+) Mφ comprised the major population of B16 tumour-infiltrating leucocytes. CT + IT treatment up-regulated molecules associated with the M1 effector Mφ phenotype [CD40, CD80, CD86, major histocompatibility complex (MHC) class II, IFN-γ, tumour necrosis factor-α (TNF-α) and IL-12] and down-regulated molecules associated with the M2 inhibitory Mφ phenotype (IL-4Rα, B7-H1, IL-4 and IL-10) on the tumour-associated Mφ compared with untreated controls. Together, the results show that CT and anti-CD40 + CpG-ODN IT synergize in the induction of anti-tumour effects which are associated with the phenotypic repolarization of tumour-associated Mφ.

Radiofrequency ablation combined with KS-IL2 immunocytokine (EMD 273066) results in an enhanced antitumor effect against murine colon adenocarcinoma.

PURPOSE: Radiofrequency ablation (RFA) is a common treatment modality for surgically unresectable tumors. However, there is a high rate of both local and systemic recurrence. EXPERIMENTAL DESIGN: In this preclinical study, we sought to enhance the antitumor effect of RFA by combining it with huKS-IL2 immunocytokine [tumor-specific monoclonal antibody fused to interleukin-2 (IL2)] in mice bearing CT26-KS colon adenocarcinoma. Mice were treated with RFA, huKS-IL2 via intratumoral injection, or combination therapy. RESULTS: Treatment of mice bearing s.c. tumors with RFA and huKS-IL2 resulted in significantly greater tumor growth suppression and enhanced survival compared with mice treated with RFA or huKS-IL2 alone. When subtherapeutic regimens of RFA or huKS-IL2 were used, tumors progressed in all treated mice. In contrast, the combination of RFA and immunocytokine resulted in complete tumor resolution in 50% of mice. Treatment of a tumor with RFA and intratumoral huKS-IL2 also showed antitumor effects against a distant untreated tumor. Tumor-free mice after treatment with RFA and huKS-IL2 showed immunologic memory based on their ability to reject subsequent challenges of CT26-KS and the more aggressive parental CT26 tumors. Flow cytometry analysis of tumor-reactive T cells from mice with complete tumor resolution showed that treatment with RFA and huKS-IL2 resulted in a greater proportion of cytokine-producing CD4 T cells and CD8 T cells compared with mice treated with RFA or huKS-IL2 alone. CONCLUSIONS: These results show that the addition of huKS-IL2 to RFA significantly enhances the antitumor response in this murine model, resulting in complete tumor resolution and induction of immunologic memory.

Tumoricidal effects of activated macrophages in a mouse model of chronic lymphocytic leukemia.

The Emu-TCL1 transgenic mouse spontaneously develops a CD5(+) B cell lymphoproliferative disorder similar to human chronic lymphocytic leukemia (CLL). Given the ineffectual T cell antitumor responses in this mouse model of CLL, we sought to determine whether combined treatment with anti-CD40 mAb (alphaCD40) and CpG-containing oligodeoxynucleotides (CpG) could exert immunotherapeutic effects. We have previously shown that macrophages activated by sequential ligation of CD40 and TLR9 could become cytotoxic against solid tumor cell lines both in vitro and in vivo. In the current study, we find that alphaCD40 plus CpG-activated macrophages induce tumor B cell apoptosis in vitro and that alphaCD40 plus CpG treatment markedly retards tumor growth in immunodeficient SCID/Beige mice following transplantation of primary tumor B cells. Our results suggest a novel immunotherapeutic strategy for CLL that may be effective even in the face of tumor or chemotherapy-induced T cell immunodeficiency.