Combination of Cetuximab and Oncolytic Virus Canerpaturev Synergistically Inhibits Human Colorectal Cancer Growth.

The naturally occurring oncolytic herpes simplex virus canerpaturev (C-REV), formerly HF10, proved its therapeutic efficacy and safety in multiple clinical trials against melanoma, pancreatic, breast, and head and neck cancers. Meanwhile, patients with colorectal cancer, which has increased in prevalence in recent decades, continue to have poor prognosis and morbidity. Combination therapy has better response rates than monotherapy. Hence, we investigated the antitumor efficacy of cetuximab, a widely used anti-epidermal growth factor receptor (EGFR) monoclonal antibody, and C-REV, either alone or in combination, in vitro and in an in vivo human colorectal xenograft model. In human colorectal cancer cell lines with different levels of EGFR expression (HT-29, WiDr, and CW2), C-REV exhibited cytotoxic effects in a time- and dose-dependent manner, irrespective of EGFR expression. Moreover, cetuximab had no effect on viral replication in vitro. Combining cetuximab and C-REV induced a synergistic antitumor effect in HT-29 tumor xenograft models by promoting the distribution of C-REV throughout the tumor and suppressing angiogenesis. Application of cetuximab prior to C-REV yielded better tumor regression than administration of the drug after the virus. Thus, cetuximab represents an ideal virus-associated agent for antitumor therapy, and combination therapy represents a promising antitumor strategy for human colorectal cancer.

CD4+ virtual memory: Antigen-inexperienced T cells reside in the naïve, regulatory, and memory T cell compartments at similar frequencies, implications for autoimmunity.

It is widely accepted that central and effector memory CD4+ T cells originate from naïve T cells after they have encountered their cognate antigen in the setting of appropriate co-stimulation. However, if this were true the diversity of T cell receptor (TCR) sequences within the naïve T cell compartment should be far greater than that of the memory T cell compartment, which is not supported by TCR sequencing data. Here we demonstrate that aged mice with far fewer naïve T cells, respond to the model antigen, hen eggwhite lysozyme (HEL), by utilizing the same TCR sequence as their younger counterparts. CD4+ T cell repertoire analysis of highly purified T cell populations from naive animals revealed that the HEL-specific clones displayed effector and central "memory" cell surface phenotypes even prior to having encountered their cognate antigen. Furthermore, HEL-inexperienced CD4+ T cells were found to reside within the naïve, regulatory, central memory, and effector memory T cell populations at similar frequencies and the majority of the CD4+ T cells within the regulatory and memory populations were unexpanded. These findings support a new paradigm for CD4+ T cell maturation in which a specific clone can undergo a differentiation process to exhibit a "memory" or regulatory phenotype without having undergone a clonal expansion event. It also demonstrates that a foreign-specific T cell is just as likely to reside within the regulatory T cell compartment as it would the naïve compartment, arguing against the specificity of the regulatory T cell compartment being skewed towards self-reactive T cell clones. Finally, we demonstrate that the same set of foreign and autoreactive CD4+ T cell clones are repetitively generated throughout adulthood. The latter observation argues against T cell-depleting strategies or autologous stem cell transplantation as therapies for autoimmunity-as the immune system has the ability to regenerate pathogenic clones.

Persistence of Autoreactive IgA-Secreting B Cells Despite Multiple Immunosuppressive Medications Including Rituximab.

IMPORTANCE: Immunobullous diseases mediated by IgA are often difficult to manage, but to date no mechanism has been proposed. Rituximab is an anti-CD20 monoclonal antibody that has demonstrated good efficacy in the treatment of refractory mucous membrane pemphigoid. However, not all cases of mucous membrane pemphigoid respond to rituximab. Herein we present a case of treatment-refractory mucous membrane pemphigoid and propose a mechanism to explain the lack of response to therapy. OBSERVATIONS: Before treatment, direct immunofluorescent examination of a biopsy sample from the patient's perilesional skin demonstrated linear deposition of IgG and IgA along the dermoepidermal junction. After a multidrug immunosuppressive regimen that included rituximab, results of a second biopsy demonstrated only IgA along the dermoepidermal junction. This finding correlated well with flow cytometry data from the same patient that demonstrated a persistent population of IgA-secreting plasmablasts/plasma cells, despite depletion of CD20⁺ cells. In addition, results of immunohistochemical analysis of the perilesional skin remained positive for CD19 and CD138 immune cells (plasmablast/plasma cell markers). CONCLUSIONS AND RELEVANCE: These findings suggest that current available immunosuppressive medications, including rituximab, cannot eliminate IgA-secreting plasmablasts/plasma cells, which are likely central to the pathophysiology of IgA-mediated immunobullous diseases. Future studies are needed to develop alternative therapeutic strategies that target autoreactive IgA-secreting plasmablasts/plasma cells.

Multimodal therapy of idiopathic pyoderma gangrenosum.

A 13-year old girl was admitted to the University of California Davis Medical Center for evaluation and treatment of cutaneous bullae and ulcerations over her lower extremities that were refractory to antibiotic therapy and incision and drainage. Her disease continued to worsen with the appearance of multiple new bullae and the progression of old ones into deep ulcers with undermined borders. Biopsy revealed a neutrophilic dermatosis and diagnostic work-up was negative for infectious or autoimmune etiologies. Given her clinical presentation, biopsy results, and negative work-up, a diagnosis of pyoderma gangrenosum (PG) was made and she was started on immunosuppressive medications. The patient was started on a multidrug regimen of prednisone and cyclosporine but remission was not achieved until the addition of adalimumab. After the inflammatory component of her disease was under control, wound care measures were maximized to promote ulcer healing. Wound care measures included compression and debridement. Upon complete closure of all wounds she was successfully transitioned to mycophenolate mofetil monotherapy for maintenance therapy. This case emphasizes the need for combinational therapy to successfully treat severe cases of PG, which are often refractory to monotherapy with prednisone or cyclosporine. It also highlights the importance of appropriate wound care to achieve complete ulcer healing.

Relapse of leukemia with loss of mismatched HLA resulting from uniparental disomy after haploidentical hematopoietic stem cell transplantation.

We investigated human leukocyte antigen (HLA) expression on leukemic cells derived from patients at diagnosis and relapse after hematopoietic stem cell transplantation (HSCT) using flow cytometry with locus-specific antibodies. Two of 3 patients who relapsed after HLA-haploidentical HSCT demonstrated loss of HLA alleles in leukemic cells at relapse; on the other hand, no loss of HLA alleles was seen in 6 patients who relapsed after HLA-identical HSCT. Single-nucleotide polymorphism array analyses of sorted leukemic cells further revealed the copy number-neutral loss of heterozygosity, namely, acquired uniparental disomy on the short arm of chromosome 6, resulting in the total loss of the mismatched HLA haplotype. These results suggest that the escape from immunosurveillance by the loss of mismatched HLA alleles may be a crucial mechanism of relapse after HLA-haploidentical HSCT. Accordingly, the status of mismatched HLA on relapsed leukemic cells should be checked before donor lymphocyte infusion.

Downregulation of GATA-2 and overexpression of adipogenic gene-PPARgamma in mesenchymal stem cells from patients with aplastic anemia.

Aplastic anemia (AA) is characterized by a reduced number of hematopoietic stem cells and fatty replacement in the bone marrow. Transcriptional factor GATA-2 plays several important roles in both hematopoiesis and adipogenesis. Decreased levels of GATA-2 compromise the proliferation and survival of hematopoietic stem cells. GATA-2 suppresses adipocyte differentiation through direct inhibition of adipogenic factors, including peroxisome proliferator-activated receptor-gamma (PPARgamma). Previous studies have shown that expression of GATA-2 is decreased in marrow CD34-positive cells in AA. To elucidate the mechanisms of fatty marrow replacement, we evaluated the mRNA expression for GATA-2 and PPARgamma in mesenchymal stem cells (MSCs) from patients with AA by quantitative real-time polymerase chain reaction. GATA-2 expression by MSCs from AA patients was significantly lower than in normal subjects. Conversely, expression of PPARgamma was significantly higher in AA patients. Western blot analysis demonstrated that protein levels of GATA-2 were lower in AA patients than those in normal subjects. Moreover, incubation with interferon-gamma induced downregulation of GATA-2 levels in MSCs from normal subjects. These findings indicate that fatty marrow replacement in AA patients can be explained by downregulation of GATA-2 and overexpression of PPARgamma in MSCs. Decreased expression of GATA-2 might be responsible for the pathogenesis and development of the clinical features of the disease.

Congenital erythroid and myeloid hypoplasia terminating myelodysplastic syndrome.

We describe a 4-month-old infant girl with congenital erythroid and myeloid hypoplasia who developed myelodysplastic syndrome. Bone marrow examination showed severe erythroid and myeloid hypoplasia without dysplastic morphology. Flow cytometry detected autoantibodies to myeloid cells, indicating a diagnosis of Diamond-Blackfan anemia with autoimmune neutropenia. The patient was administered prednisolone and rituximab, which brought the neutrophil count and hemoglobin level to within the normal range. However, bicytopenia recurred at the age of 22 months. She was diagnosed with myelodysplastic syndrome because of trilineage dysplasia and the clonal abnormality of 46,XX,dup(1)(q21;q32) in bone marrow. She was transplanted with cord blood from an unrelated human leukocyte antigen-matched donor and has since remained in complete remission for 20 months.

Quantification of granulocyte-macrophage colony-stimulating factor hypersensitivity in juvenile myelomonocytic leukemia by 3H-thymidine assay.

Recent molecular studies have revealed that the GM-CSF/RAS signaling pathway plays a central role in the pathogenesis of juvenile myelomonocytic leukemia (JMML). CFU-GM colony assay is an important test for GM-CSF hypersensitivity in patients with JMML, but requires specific skills. We established a simple and easy quantification method to test GM-CSF hypersensitivity, using a (3)H-thymidine assay. With this quantification method, JMML patients with RAS mutations showed significantly higher GM-CSF sensitivity than JMML patients with PTPN11 mutations. This method will be useful not only in the diagnosis of JMML, but also to evaluate the difference of GM-CSF sensitivity among patients.

Increased midkine gene expression in childhood B-precursor acute lymphoblastic leukemia.

Midkine (MK) is a heparin-binding growth factor that is overexpressed in a number of solid cancers. However, expression in acute leukemia has not been clarified. We examined MK gene expression using real-time PCR in 94 children with acute leukemia. In 30 of the 41 patients with B-precursor ALL, MK gene expression was overexpressed than normal BM. MK gene was also overexpressed in more than half of patients with FAB M1 and M2 types of AML. Quantification of MK gene by real-time PCR offers particular promise as a prognostic marker and a marker for minimal residual disease in children with B-precursor ALL.