A tumor vaccine containing anti‐CD3 and anti‐CD28 bispecific antibodies triggers strong and durable antitumor activity in human lymphocytes

Abstract

We recently reported on newly designed virus‐targeted bispecific CD3‐ and CD28‐binding molecules for human T‐cell activation. When bound via one arm to a human virus‐modified tumor cell vaccine, these reagents caused a polyclonal T‐cell response and overcame the potential various T‐cell evasion mechanisms of tumor cells. In our current study, we demonstrated the induction of strong antitumor activity in human lymphocytes upon coincubation with a virus‐modified tumor vaccine containing anti‐CD3 and anti‐CD28 bispecific antibodies. Blood mononuclear cells or purified T cells that were coincubated with such a tumor vaccine for 3 days were able to destroy monolayers of human breast carcinoma and other carcinoma cells. Serial transfer to new tumor cell monolayers revealed antitumor cytotoxic activity in such effector cells that lasted for about 10 days. Nontumor target cells appeared to be much less sensitive to the activated effector cells. Although the bispecific molecules alone did not activate effector cells, their binding to virus‐infected tumor cells was important and more effective than their binding to free virus. Antitumor activity of the activated effector cells was mediated through soluble factors as well as through direct cell contact of effector cells with the nontargeted bystander tumor cells. Since the virus‐modified tumor vaccine is well tolerated and already exhibits a certain effectiveness in cancer patients, the combination with new bispecific molecules has the potential to introduce additional antitumor effects. The reagents can also be combined with Newcastle Disease Virus (NDV)‐based oncolytic virotherapy. © 2005 Wiley‐Liss, Inc.

Multi-walled carbon nanotubes conjugated to tumor protein enhance the uptake of tumor antigens by human dendritic cells in vitro

“…To study the issue, two groups of DC were first incubated with either TumorP or CNT-TumorP for 2 days, mixed with fresh autologous lymphocytes (effector cells) at the ratio of 1:10, and co-incubated with the MCF7 tumor cells (target cells) for 3 more days. The anticancer cytotoxiciy of the lymphocytes was then evaluated using a standard MTS cytotoxicity assay [10]. As shown in Figure 1E, the DC pretreated with CNTTumorP induced higher anti-tumor cytotoxicity (P < 0.05) at most E:T ratios, suggesting that CNT-TumorP enhanced the function of DC to induce anticancer response in lymphocytes.…”

Recombinant Newcastle disease virus (NDV) with inserted gene coding for GM-CSF as a new vector for cancer immunogene therapy

“…It enables to test human PBMC-mediated bystander antitumor, cytotoxic or cytostatic effects on the tumor monolayer. While we previously performed the tumor neutralization assay (TNA) in 96-well plates with 750 vaccine cells, 18 we had to increase the vaccine cell number to have enough of the therapeutic gene product These assays were performed with PBMC from 14 different healthy donors because of individual variability in activity. While in absence of virus infection the vaccine cells (V) did not induce tumor growth inhibition (TGI) (see Figure 5), we observed about 30% TGI when virusmodified vaccine cells (VN) were added on top of the tumor cell monolayer.…”

Cross-infection of tumor cells by contact with T lymphocytes loaded with Newcastle disease virus

“…Details of the tumor neutralization assay (TNA) were described by Haas et al (29). MCF-7 cells were co-cultured with NDV modified PBTC for 2 days to analyze the anti-tumor effect after viral hitchhiking on PBTC or polyclonally activated PBTC.…”

“…The color alteration can be measured with an ELISA reader (Perkin-Elmer Wallac, Freiburg, Germany) at 490 nm. The percent tumor growth inhibition (TGI) was calculated as described (29).…”

“…7). For this we employed the tumor neutralization assay (TNA) previously described by Haas et al (29), in which tumor monolayers are co-cultured with the T cells for several days. The anti-tumor effect is then measured by uptake of MTS by the remaining live tumor cells.…”