Phase I trial of Lipovaxin-MM, a novel dendritic cell-targeted liposomal vaccine for malignant melanoma.

INTRODUCTION: In this phase I study using a 3 + 3 dose escalation design, the safety, dose-limiting toxicity (DLT), immunogenicity and efficacy of intravenous Lipovaxin-MM-a multi-component dendritic cell-targeted liposomal vaccine against metastatic melanoma-was investigated. METHODS: Twelve subjects with metastatic cutaneous melanoma were recruited in three cohorts. Patients in Cohort A (n = 3) and Cohort B (n = 3) received three doses of 0.1 and 1 mL of Lipovaxin-MM, respectively, every 4 weeks. Patients in Cohort C (n = 6) received four doses of 3 mL vaccine weekly. Immunologic assessments of peripheral blood were made at regular intervals and included leukocyte subsets, cytokine levels, and Lipovaxin-MM-specific T-cell and antibody reactivities. Tumor responses were assessed by RECIST v1.0 at screening, then 8 weekly in Cohorts A and B and 6 weekly in Cohort C. RESULTS: Of a total of 94 adverse events (AEs) reported in ten subjects, 43 AEs in six subjects were considered to be possibly or probably vaccine-related. Most (95%) vaccine-related AEs were grade 1 or 2, two (5%) grade 3 vaccine-related AEs of anemia and lethargy were recorded, and higher grade AEs and DLTs were not observed. No consistent evidence of vaccine-specific humoral or cellular immune responses was found in post-immunization blood samples. One patient had a partial response, two patients had stable disease, and the remaining patients had progressive disease. CONCLUSIONS: Lipovaxin-MM was well tolerated and without clinically significant toxicity. Immunogenicity of Lipovaxin-MM was not detected. Partial response and stable disease were observed in one and two patients, respectively.

Splice variants of the condensin II gene Ncaph2 include alternative reading frame translations of exon 1.

Condensins I and II are five-protein complexes that are important for the condensation of chromatin. They are essential for mitosis and important for regulating gene expression during interphase. Here, we investigated the transcription and translation of the mouse Ncaph2 gene, which encodes a subunit of condensin II. We identified three splice variants within the first exon, a NAGNAG splice variant at the beginning of exon 16 and alternative 3'-UTRs. In total, Ncaph2 is potentially capable of generating 12 unique mRNA transcripts and six unique proteins. We confirm that Ncaph2 can generate three different N-termini, all encoded by exon 1, one of which is translated from an alternative reading frame. This alternative reading frame splice variant appears to be a novel outcome of splicing. If this is applicable to other genes, it would account for a previously unappreciated level of eukaryotic protein diversity.

Defective T-cell function leading to reduced antibody production in a kleisin-beta mutant mouse.

The recently described nessy (Ncaph2nes/nes) mutant mouse strain has a defect in T-cell development caused by a mutation in the ubiquitous kleisin-beta (also known as Ncaph2). Kleisin-beta is a subunit of the condensin II complex involved in chromosome condensation during mitosis. The nessy phenotype is characterized by CD44hi CD8+ peripheral T cells, 10-20% of normal thymocyte numbers and 2.5-fold fewer alphabeta T cells in the spleen compared with wild-type mice. In this study we examined the effect of the nessy mutation in kleisin-beta on the immune response by challenging mice with an attenuated strain of Salmonella. Results showed that nessy mice control bacterial load as effectively as wild-type mice but exhibit a reduced antibody titre. Further experiments revealed that while the T-dependent antibody response was diminished in nessy mice the T-independent response was normal, suggesting that the defect was the result of T-cell function and not B-cell function. In vitro activation assays showed that nessy T cells have a lower capacity to up-regulate the early activation marker CD69 than wild-type T cells. Upon transfer into RAG-/- mice, nessy and wild-type CD4 T cells showed equivalent homeostatic proliferation, while nessy CD8 T cells proliferated more than their wild-type counterparts. When cultured with anti-T-cell receptor beta or concanavalin A, nessy T cells were found to die faster than wild-type T cells. These data indicate that kleisin-beta is required for a normal immune response, and represent the first demonstration of a role for kleisin-beta in T-cell function.

A mutation in a chromosome condensin II subunit, kleisin beta, specifically disrupts T cell development.

Condensins are ubiquitously expressed multiprotein complexes that are important for chromosome condensation and epigenetic regulation of gene transcription, but whose specific roles in vertebrates are poorly understood. We describe a mouse strain, nessy, isolated during an ethylnitrosourea screen for recessive immunological mutations. The nessy mouse has a defect in T lymphocyte development that decreases circulating T cell numbers, increases their expression of the activation/memory marker CD44, and dramatically decreases the numbers of CD4(+)CD8(+) thymocytes and their immediate DN4 precursors. A missense mutation in an unusual alternatively spliced first exon of the kleisin beta gene, a member of the condensin II complex, was shown to be responsible and act in a T cell-autonomous manner. Despite the ubiquitous expression and role of condensins, kleisin beta(nes/nes) mice were viable, fertile, and showed no defects even in the parallel pathway of B cell lymphocyte differentiation. These data define a unique lineage-specific requirement for kleisin beta in mammalian T cell differentiation.