Pulsing of dendritic cells with cell lysates from either B16 melanoma or MCA-106 fibrosarcoma yields equally effective vaccines against B16 tumors in mice

Abstract

Background and Objectives: Dendritic cells (DC) pulsed in vitro with a variety of antigens have proved effective in producing specific antitumor effects in vivo. Experimental evidence from other laboratories has confirmed that shared antigens can be encountered in histologically distinct tumors. In our experiments, we set out to evaluate the immunotherapeutic potential of vaccines consisting of DC pulsed with MCA‐106 fibrosarcoma or B16 melanoma cell lysates and to determine whether a cross‐reactivity exists between the two tumors. Methods DC were prepared from the bone marrow of C57BL/6 (B6) mice by culturing progenitor cells in murine granulocyte‐macrophage colony‐stimulating factor (GM‐CSF). They were separated into three equal groups and were either pulsed with B16 melanoma cell lysates (BDC), pulsed with tumor extract from the syngeneic fibrosarcoma MCA‐106 (MDC), or left unpulsed (UDC). DC were then used to immunize three groups of mice, with all mice receiving two weekly intravenous (IV) doses of 1 × 106 DC from their respective preparations on days −14 and −7. A fourth group of control mice were left untreated. On day 0, all mice were challenged with subcutaneous injections of 1 × 105 B16 and 1 × 105 MCA tumor cells, administered in the left and right thighs, respectively. After the inoculations, the mice were monitored closely with respect to tumor growth and survival. Results The MDC mice developed specific cellular immunity directed against not only MCA‐106 tumor cells, but also against B16 melanoma, as measured through chromium‐release assays of splenocyte preparations, while remaining ineffective at killing both L929 fibroblasts and CT26 tumor cells. By day 30 after tumor inoculations, control mice manifested the largest B16 tumor volumes at a mean of 2185 mm3, followed by the UDC, MDC, and BDC groups at 92 mm3 (P = 0.00008), 3 mm3 (P = 0.000002), and 2 mm3 (P = 0.00004), respectively. The survival data mirrored this pattern, with control animals displaying the shortest mean survival time (37.1 ± 4.0 days), followed by UDC (44.8 ± 6.6), MDC (56.2 ± 14.7), and BDC (56.4 ± 18.3) animals. No significant differences were noted between MCA‐106 and B16 cell lysate‐pulsed DC vaccines with respect to their abilities to inhibit B16 tumor growth and to prolong survival. These findings were confirmed using a B16 pulmonary metastasis model. Likewise, vaccination with interferon‐γ gene‐modified MCA‐106 tumor cells was shown to be effective at protecting against a subsequent subcutaneous B16 tumor challenge in 3 of 4 mice observed. Conclusions These results demonstrate that immunization with antigen‐pulsed DC confers cellular immunity, retards tumor growth, and prolongs the survival of tumor‐challenged mice. The ability of MCA‐106 cell lysate‐pulsed DC vaccines to inhibit the growth of subcutaneous B16 tumors also suggests the presence of shared tumor‐associated antigens between these two histologically distinct tumors. J. Surg. Oncol. 1998;68:79–91. © 1998 Wiley‐Liss, Inc.

Trial watch: Dendritic cell-based anticancer immunotherapy

“…[136][137][138][139][140][141] However, the DC-based vaccine most commonly used so far involves the loading of DCs with a source of TAAs followed by their stimulation with defined maturation cocktails. 142,143 Ex vivo, DC loading with TAAs is typically accomplished by (1) co-culturing iDCs with either autologous or allogeneic tumor-cell lysates [71][72][73][74][75][76][77][78][79][80][144][145][146] or recombinant TAAs; [81][82][83][84][85][86][87][88]147 (2) transfecting DCs with vectors or RNAs coding for TAA(s), or even bulk RNA derived from tumor cells; 41,[148][149][150][151][152] and (3) creating fusions between DCs and incapacitated malignant cells (also known as "dendritomes").…”

CpG DNA: A potent signal for growth, activation, and maturation of human dendritic cells

“…The use of DCs as a cellular adjuvant is a promising approach in immunotherapy of infectious disease and cancer. Numerous animal models demonstrate conclusively that ex vivo generated DCs pulsed with protein antigen are useful for the immunotherapy of infectious diseases and cancer (11)(12)(13)(14)(15)(16). Initial clinical studies indicate that tumor antigen-pulsed DCs can be effective in the immunotherapy of cancer patients (17)(18)(19)(20).…”

Concurrent delivery of tumor antigens and activation signals to dendritic cells by irradiated CD40 ligand-transfected tumor cells resulted in efficient activation of specific CD8+ T cells

“…1 Protective cellular immunity was induced by vaccination of DCs loaded with various forms of tumor antigens (Ag) in several animal models. [2][3][4] Early clinical trials using tumor Ag-pulsed DCs as vaccines for the treatment of various advanced malignancies have been reported. [5][6][7] Several DC-based clinical trials employed preidentified tumor-associated Ag (TAA) or synthetic peptides containing cytotoxic T lymphocyte (CTL) epitopes of known TAA as the source of Ag.…”

“…Alternative approaches have been explored to expand DC-based therapy to cancers for which appropriate TAA or relevant CTL epitopes have not been determined. These approaches include pulsing DCs with tumor cell lysates, 3,4,6,8,9 tumor-derived RNA, 10 necrotic or apoptotic tumor cells, [11][12][13][14][15] and fusing DCs with tumor cells. 16,17 Gene-modified tumor cell vaccines, which also use undefined tumor material as the source of tumor Ag, represent another promising new approach for cancer therapy.…”