Purpose: To test the feasibility, safety, immunogenicity, and clinical efficacy of an autologous vaccine of leukocyte-derived heat shock protein 70-peptide complexes (Hsp70PC), in conjunction with imatinib mesylate, in patients with chronic myeloid leukemia (CML) in chronic phase. Experimental Design: Patients had cytogenetic or molecular evidence of disease, despite treatment with imatinib mesylate for all except one patient, at the beginning of study. Hsp70PCs were purified from the leukopheresed peripheral blood mononuclear cells and were administered in eight weekly intradermal injections at 50 Ag/dose without adjuvant. Clinical responses were assessed by bone marrow analysis before and after vaccinations. An IFN-g enzyme-linked immunospot assay was used to estimate the effect of treatment on natural killer cells and T cells against CML. Results: Twenty patients were treated. The manufacturing of Hsp70PCs was successful and the administration was safe for all patients. Minimal or no side effects were reported. Clinical responses were seen in 13 of 20 patients as measured by cytogenetic analysis of bone marrow Philadelphia chromosome^positive cells in metaphases and/or, when possible, the level of Bcr/ Abl transcript by PCR. Immunologic responses were observed in 9 of 16 patients analyzed, characterized by an increase in the frequency of CML-specific IFN-g-producing cells and IFN-gsecreting natural killer cells in the blood. A significant correlation between clinical responses and immunologic responses was observed. Conclusions: Autologous Hsp70PC vaccination is feasible and safe. When combined with imatinib mesylate, it is associated with immunologic and possible clinical responses against CML in chronic phase.

A small number of testicular germ cell tumours are refractory to current chemotherapy regimens. DNA topoisomerase I is the target for several new drugs and a potential candidate treatment for chemorefractory germ cell tumours. DNA topoisomerase IIa is the target for etoposide, which is currently used regularly in germ cell tumour treatment. The expression of DNA topoisomerase I and IIa were therefore assessed immunohistochemically in a range of testicular tumours, especially those with persistent malignant elements on retroperitoneal lymph node dissection. Pre-chemotherapy orchidectomy specimens were matched with postchemotherapy retroperitoneal lymph node dissections to examine changes in expression. There was considerable variation in the expression of topoisomerase I in different tumour types. Both yolk sac tumours and teratoma, mature showed universal expression of topoisomerase I, while 38% of seminomas and 30% of embryonal carcinomas were positive. Strong topoisomerase IIa expression was found in embryonal carcinoma. There was a negative correlation between topoisomerase I and IIa expression (P=0.004) and downregulation of topoisomerase IIa after chemotherapy (P=0.02). Topoisomerase I expression appears to increase in those cases with residual teratoma, mature, but is largely unchanged in those cases remaining as embryonal carcinoma. These results suggest that topoisomerase I inhibitors may be useful in chemorefractory germ cell tumours, especially yolk sac tumours and where there are unresectable residual teratoma, mature deposits.

Experiments have been designed to test the hypothesis that soluble mediator production and T-cell-mediated cytotoxicity are necessarily related phenomena, and that soluble mediators may be involved in the mechanism of cytolysis. To this end, agents known to inhibit T-cell-mediated lysis in vitro have been studied for their effects on the production of two lymphocyte-derived mediators, lymphotoxin (LT) and migration inhibitory factor (MIF). A clear dissociation between mediator production and cell-mediated cytolysis was found using inhibitors of protein synthesis. Pactamycin and emetine, in doses of 10–7 M to 10–6 M, suppressed production of MIF and LT with only slight effect on killing of mastocytoma cells by immune T cells. On the other hand colchicine and vinblastine inhibited T-cell-mediated cytolysis in a dose-related manner but had no significant effect on either MIF or LT production, A striking dichotomy was also observed after augmentation of intracellular cyclic 3'5' adenosine monophosphate (cAMP) levels with cholera enterotoxin. Increased cAMP levels were associated with abrogation of direct lytic activity, but were without significant effect on MIF or LT production in guinea pigs or mice. These findings indicate that mediator production and direct lymphocyte-mediated cytolysis can be experimentally dissociated and represent independent cell-mediated immune functions.