ALBERT

Description: Background: Preclinical models have demonstrated enhanced cancer vaccine efficacy when administered early following ASCT and accompanied by vaccine-primed lymphocyte infusion. Methods: Patients with untreated myeloma were enrolled and underwent a bone marrow harvest to obtain tumor cells for vaccine processing. Patients eligible for ASCT following induction chemotherapy received a pre-transplant vaccination followed by leukapheresis to collect “primed” lymphocytes that were reinfused with the stem cell graft. Eight post-transplant vaccinations were administered at 3-week intervals starting 6 weeks posttransplant. The vaccine formulation consisted of irradiated autologous tumor cells admixed with GM-CSF-secreting K562 cells (CG9962) at a ratio of 5:2, respectively. Three dose levels were assigned (1, 4, and 10 x107 tumor cells/vaccination) based on tumor cell yield from the bone marrow harvest. Results: 22 patients underwent tumor harvest, 18 completed induction chemotherapy, and 16 proceeded to vaccination (1 at 1 x 107,4 at 4x107, and 13 at 10x107) and ASCT. At baseline, the median b2 microglobulin was 4 (2–14) and 35% had an IgA subtype. No grade 3/4 vaccine-related toxicities were observed. Median time to neutrophil engraftment (〉500) and platelet engraftment (〉50K) was 10 days. Local vaccine injection site reactions were observed in all patients. Delayed-type hypersensitivity (DTH) reactions to injections of irradiated autologous tumor cells were induced in only 1/15 patients after 4 post-transplant vaccines, but 4/10 were positive at one year post transplant. Induction of autologous tumor-reactive antibodies as well as antibodies reactive against CG9962 cells was observed. In vitro studies have demonstrated the induction and adoptive transfer of tumor-specific cellular immune responses that can be followed throughout the post-transplant period. Reproducible serum GM-CSF levels were achieved with repeated vaccinations suggesting no increased clearance of CG9962 cells due to induction of an allogeneic immune response. Of the 16 patients that have completed the ASCT, there were 6 complete and 5 partial remissions, for an overall response rate of 69%. Three patients with rising paraprotein levels early post-transplant have demonstrated paraprotein declines following initiation of post-transplant vaccines, suggesting a possible vaccine-mediated effect. Conclusions: These data demonstrate the feasibility of this vaccine approach and show the therapeutic potential of K562 GVAX® vaccination in the ASCT setting in multiple myeloma.

Description: Increased understanding of the local injection site infiltrate in response to tumor vaccines may facilitate more effective anti-cancer vaccination strategies. A pilot vaccination strategy was developed to determine if K562/GM-CSF immunotherapy could enhance T cell reactivity and clinical responses in CML patients undergoing therapy with imatinib mesylate. K562/GM-CSF is a tumor vaccine derived from a CML cell line that expresses several defined CML associated antigens and has been genetically modified to secrete GM-CSF. We undertook a correlative project comparing the cellular infiltrates from pre- and post-vaccination skin biopsies in this immunotherapy trial. GM-CSF producing tumor vaccines are effective in recruiting antigen presenting cells (APCs), however alone they are insufficient to initiate APC maturation. Because topical imiquimod (a Toll-like receptor 7 agonist) is known to enhance the in vivo maturation of the recruited APCs, the vaccines (1 x 10*8 cells distributed over 10 injection sites) were given with or without topical 5% imiquimod cream. Imiquimod was applied 4 hrs post-vaccination and then 3d and 5d post-vaccination to injection sites, with at least 1 site left without imiquimod treatment. A series of 4 vaccines were administered in 3 wk intervals. Six mm punch biopsies were taken at baseline, and 3d following the 1st and 4th vaccination. Biopsies were performed at the imiquimod site with the largest area of induration, as well as a site not exposed to imiquimod. Immunohistochemistry of CD3, CD4, CD8, CD1a (Langerhans cell (LC)), factor XIIIa (dermal dendritic cell), and CD68 (monocyte/macrophage) and Geimsa staining was performed. Staining is reported as number of live cells per mm2 in the epidermis and dermis for CD1a+ cells and dermis for the remaining stains. Fifteen subjects agreed to the procedures as part of the clinical trial. Mean area of induration of imiquimod sites was increased significantly compared to the non-imiquimod sites after both the first (p=0.005) and fourth vaccinations (p=0.068). Geimsa staining revealed significant increases in proportion of neutrophils, eosinophils, and mononuclear cells to total number of staining cells after the 1st vaccination in the sites treated with imiquimod compared to the pre-vaccination biopsies while the increases at the sites without imiquimod treatment did not reach statistical significance. We observed increases in CD3+, CD4+, and CD8+ cells at post-vaccination sites. Interestingly, the total number of CD1a+ LCs in the area measured did not appear to be affected by the administration of imiquimod and was constant after vaccinations. However, distribution of CD1a+ LCs shifted from the epidermis to the dermis after vaccination. In addition we observed recruitment of factor XIIIa+ dermal dendritic cells and CD68+ macrophages to the vaccination site that was increased by imiquimod. Epidermal APCs known as LCs migrate to the dermis, yet maintain homeostasis of the total LCs following vaccination independent of Imiquimod application. A correlation across subjects between these histologic features and clinical response to vaccination is on-going.

Description: Despite high rates of clinical responses to IM, molecular complete responses are rare. The curative potential of allo transplantation and donor lymphocyte infusions underscores CML’s responsiveness to T cell mediated immunity. K562/GM-CSF is a tumor vaccine derived from a CML cell line that expresses several defined CML associated antigens and has been genetically engineered to produce GM-CSF. A pilot vaccination strategy was developed to determine if K562/GM-CSF immunotherapy in combination with IM could enhance T cell reactivity and clinical responses in pts having persistent, measurable disease by FISH or RT-PCR despite 1 or more years on IM. Eligible pts also had a major cytogenetic response (