Induction of high-titer IgG antibodies against multiple leukemia-associated antigens in CML patients with clinical responses to K562/GVAX immunotherapy.

The ability to target myeloid leukemia with immunotherapy would represent a significant therapeutic advance. We report here immunological analysis of clinical trials of primary and secondary vaccination with K562/GM-CSF immunotherapy in adult chronic phase chronic myeloid leukemia patients (CML-CP) with suboptimal responses to imatinib mesylate. Using serological analysis of recombinant cDNA expression libraries of K562 with autologous vaccinated patient serum, we have identified 12 novel chronic myeloid leukemia-associated antigens (LAAs). We show that clinical responses following K562/GM-CSF vaccination are associated with induction of high-titer antibody responses to multiple LAAs. We observe markedly discordant patterns of baseline and induced antibody responses in these identically vaccinated patients. No single antigen was recognized in all responses to vaccination. We demonstrate that an additional 'booster' vaccination series can be given safely to those with inadequate responses to initial vaccination, and is associated with more frequent induction of IgG responses to antigens overexpressed in K562 vaccine compared with primary CML-CP. Finally, those with induced immune responses to the same LAAs often shared HLA subtypes and patients with clinical responses following vaccination recognized a partially shared but non-identical spectrum of antigens; both findings have potentially significant implications for cancer vaccine immunotherapy.

Immunologic recovery following autologous stem-cell transplantation with pre- and posttransplantation rituximab for low-grade or mantle cell lymphoma.

BACKGROUND: Rituximab may improve transplant outcomes but may delay immunologic recovery. PATIENTS AND METHODS: Seventy-seven patients with low-grade or mantle cell lymphoma received autologous stem-cell transplantation (ASCT) on a phase II study. Rituximab 375 mg/m(2) was administered 3 days before mobilization-dose cyclophosphamide, then weekly for four doses after count recovery from ASCT. Immune reconstitution was assessed. RESULTS: Sixty percent of transplants occurred in first remission. Actuarial event-free survival (EFS) and overall survival (OS) were 60% and 73%, respectively, at 5 years, with 7.2-year median follow-up for OS in surviving patients. Median EFS was 8.3 years. Older age and transformed lymphomas were independently associated with inferior EFS, whereas day 60 lymphocyte counts did not predict EFS or late infections. Early and late transplant-related mortality was 1% and 8%, with secondary leukemia in two patients. B-cell counts recovered by 1-2 years; however, the median IgG level remained low at 2 years. Late-onset idiopathic neutropenia, generally inconsequential, was noted in 43%. CONCLUSION: ASCT with rituximab can produce durable remissions on follow-up out to 10 years. Major infections do not appear to be significantly increased or to be predicted by immune monitoring.

Salvage transplantation for allograft failure using fludarabine and alemtuzumab as conditioning regimen.

Graft failure after allogeneic blood or marrow transplantation, although generally uncommon, can be a devastating complication. This report includes the outcome of nine patients who received a salvage transplant for failure to engraft after one (n=8) or 2 (n=1) prior transplants. Eight patients received allografts from the original donor. All received fludarabine 30 mg/m(2) i.v. and alemtuzumab 20 mg i.v. daily from days -6 to -2. Daily CYA was begun on day -2, and the allograft was infused on day 0. The therapy was well tolerated with low toxicity, and all nine patients engrafted, recovering neutrophils at a median of 12 days after transplant. Four patients died: two of relapse, one of a fungal infection in the setting of GVHD and one of multiple sclerosis. The combination of fludarabine and alemtuzumab is an effective and well-tolerated salvage conditioning regimen for patients who experience graft failure after blood or marrow transplants.

gp100/pmel17 and tyrosinase encode multiple epitopes recognized by Th1-type CD4+T cells.

CD4+ T cells modulate the magnitude and durability of CTL responses in vivo, and may serve as effector cells in the tumour microenvironment. In order to identify the tumour epitopes recognized by tumour-reactive human CD4+ T cells, we combined the use of an HLA-DR4/peptide binding algorithm with an IFN-gamma ELISPOT assay. Two known and three novel CD4+ T cell epitopes derived from the gp 100/pmel17 and tyrosinase melanocyte-associated antigens were confirmed or identified. Of major interest, we determined that freshly-isolated PBMC frequencies of Th1-type CD4+ T recognizing these peptides are frequently elevated in HLA-DR4+ melanoma patients (but not normal donors) that are currently disease-free as a result of therapeutic intervention. Epitope-specific CD4+ T cells from normal DR4+ donors could be induced, however, after in vitro stimulation with autologous dendritic cell pulsed with antigens (peptides or antigen-positive melanoma lysates) or infected with recombinant vaccinia virus encoding the relevant antigen. Peptide-reactive CD4+ T cells also recognized HLA-DR4+ melanoma cell lines that constitutively express the relevant antigen. Based on these data, these epitopes may serve as potent vaccine components to promote clinically-relevant Th1-type CD4+ T cell effector function in situ.

Autologous human monocyte-derived dendritic cells genetically modified to express melanoma antigens elicit primary cytotoxic T cell responses in vitro: enhancement by cotransfection of genes encoding the Th1-biasing cytokines IL-12 and IFN-alpha.

DNA-based immunization strategies designed to elicit cellular antitumor immunity offer an attractive alternative to protein- or peptide-based approaches. In the present study we have evaluated the feasibility of DNA vaccination for the induction of CTL reactivity to five different melanoma Ags in vitro. Cultured, monocyte-derived dendritic cells (DC) were transiently transfected with plasmid DNA encoding human MART-1/Melan-A, pMel-17/gp100, tyrosinase, MAGE-1, or MAGE-3 by particle bombardment and used to stimulate autologous PBMC responder T cells. CTL reactivity to these previously identified melanoma Ags was reproducibly generated after two or three stimulations with genetically modified DC. Co-ordinate transfection of two melanoma Ag cDNAs into DC promoted CTL responders capable of recognizing epitopes from both gene products. Coinsertion of genes encoding the Th1-biasing cytokines IL-12 or IFN-alpha consistently enhanced the magnitude of the resulting Ag-specific CTL reactivity. Importantly, DC transfected with a single melanoma Ag cDNA were capable of stimulating Ag-specific CTL reactivity restricted by multiple host MHC alleles, some of which had not been previously identified. These results support the inherent strengths of gene-based vaccine approaches that do not require prior knowledge of responder MHC haplotypes or of relevant MHC-restricted peptide epitopes. Given previous observations of in situ tumor HLA allele-loss variants, DC gene vaccine strategies may elicit a greater diversity of host therapeutic immunity, thereby enhancing the clinical utility and success of such approaches.

Mean genes and the biology of aggression: a critical review of recent animal and human research.

Recent genetic work has suggested that abnormalities in serotonin biochemistry are directly causally linked to aggressive behavior, and there appears to be a consensus in the psychiatric literature that low levels of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid are specifically associated with impulsive violent behavior. We review the limitations of the genetic studies and conduct a meta-analysis of 39 studies linking 5-HIAA to aggression in humans. No differences in mean 5-HIAA levels were found between groups of violent impulsive psychiatric patients and groups of subjects diagnosed with other psychiatric or medical conditions not considered to involve violence once these levels had been corrected for three nonpsychiatric sources of variation (age, sex and height). However, mean 5-HIAA levels in both of these groups were lower than the mean corrected level in groups of normal healthy volunteers. The results confirm an association between low 5-HIAA levels and psychiatric disorders, but fail to support any specific relationship between low 5-HIAA levels and impulsive aggression or criminality. It is premature and misleading to speak of "mean genes" (Hen 1996) or a specific neurochemistry of aggressive behavior.