T-cell retargeting using bispecific monoclonal antibodies in a rat colon carcinoma model. I. Significant bispecific lysis of syngeneic colon carcinoma CC531 is critically dependent on prolonged preactivation of effector T-lymphocytes by immobilized anti-T-cell receptor antibody.

In order to develop a rat model that reflects human weakly or nonimmunogenic tumor-host relationships and allows investigation of T-cell retargeting with bispecific monoclonal antibodies in vivo, we prepared several mixed hybridomas. One fusion partner was the anti-rat-T-cell receptor (TCR)-framework hybridoma R73 and the others were hybridomas producing antibodies against CC531, a Wag rat colon carcinoma. Stimulation of Wag rat spleen cells with immobilized R73 mAb and rIL-2 yielded predominantly CD8 positive effector T-lymphocytes, which lysed control P815 target cells efficiently in R73-mediated reverse antibody-dependent cellular cytotoxicity (ADCC). The capacity of these effectors to cause significant hybrid antibody-mediated lysis of CC531 emerged several days later, was critically dependent on prolonged stimulation with immobilized R73, and was associated with increased N-alfa-benzyloxycarbonyl-L-lysine thiobenzyl esterase content.

Neurolymphomatosis of the median nerve.

A patient with a non-Hodgkin's lymphoma had a painful axonal neuropathy of the median nerve due to lymphomatous infiltration. The median nerve lesion was the only site of tumor recurrence for 5 months and could be diagnosed with MRI. The median neuropathy responded to chemotherapy.

[Immunology in clinical practice. XII. Indications for T-Cell-mediated immunotherapy of cancer]. / Immunologie in de medische praktijk. XII. Indicaties voor T-celgemedieerde immunotherapie van kanker.

In a limited number of cases, T cell based cancer immunotherapy has proven its clinical efficacy. Indications are restricted to certain haematological malignancies, relapsed after allogeneic bone marrow transplantation, and tumours against which an autologous T cell response can be elicited or boosted, such as melanomas and renal carcinomas. T cell based immunotherapy of non-immunogenic tumors is possible using bispecific antibodies.

T-cell based cancer immunotherapy: direct or redirected tumor-cell recognition?

In development of strategies for immunotherapy of cancer a new emphasis is emerging, termed T-cell retargeting, which involves artificial redirection of cytotoxic T lymphocytes (CTL) against cancer cells, using bispecific reagents. In this article, Gideon Beun, Cornelis van de Velde and Gert Jan Fleuren evaluate this potential strategy for cellular immunotherapy, and propose how the gap between in vitro results and clinical application might be bridged.

T-cell retargeting using bispecific monoclonal antibodies in a rat colon carcinoma model: III. Activation of resting T cells and tumor neutralization induced by bispecific antibodies.

We investigated the ability of two murine bispecific anti-rat T-cell receptor x anti-tumor antibodies, composed of dual IgG1 or IgG1 x IgG2b isotypes, to activate resting T lymphocytes in fresh, unfractionated rat spleen cell populations. The dual IgG1 antibody was found to be a potent activator, whereas the IgG1 x IgG2b antibody was considerably less active. However, on prolonged cocultivation of spleen cells and syngeneic CC531 colon tumor cells, both antibodies induced spleen cell proliferation and tumor neutralization if exogenous IL-2 was present. Their functional activities suggest that these bispecific antibodies should be able, upon in vivo administration, to recruit endogenous T lymphocytes as activated, cytotoxic effector cells. Exploitation of these biological characteristics may be incorporated in the design of therapeutic trials in this model.

T-cell retargeting using bispecific monoclonal antibodies in a rat colon carcinoma model: IV. Tumor neutralization in Winn type assays.

We investigated the ability of bispecific anti-T-cell receptor x anti-tumor antibodies, destined for the study of T-cell retargeting in a rat colon carcinoma model, to enhance tumor neutralization by polyclonally activated CD8+ T lymphocytes in hepatic subcapsular Winn type assays against syngeneic CC531 colon carcinoma cells. Attempts to improve on initially unsatisfactory results were guided by a 3-day in vitro cocultivation assay, demonstrating that recombinant IL-2 (rIL-2) at concentrations as low as 1 U/ml would promote tumor neutralization by retargeted effector cells. Accordingly, we found that a nontoxic regimen of rIL-2 administration, 200,000 U subcutaneously every 8 h for 3 days, strongly enhanced natural killer-like as well as retargeted anti-tumor activity in Winn assays and enabled retargeted effector cells to prevent tumor growth in the majority of animals. These results back up and direct future attempts to treat established tumor lesions.

Low-dose rIL-2-induced remission of disseminated CD30+ anaplastic large-cell lymphoma through reinforcement of presumed T-cell-mediated tumor cell killing, complicated by unilateral drowning of lymphoma-infiltrated lung.

We report on the immuno-oncologic analysis and treatment of a remarkable case of disseminated CD30+ anaplastic non-Hodgkin's lymphoma. Its clinical course was characterized by repeated spontaneous regressions, which were probably due to a T-cell-mediated anti-lymphoma immune reaction, as tumor-infiltrating T lymphocytes were consistently observed in sections of lymphoma lesions and found to express high-affinity receptors for interleukin-2 (IL-2). This marker may be particularly suitable to predict a response to low-dose recombinant IL-2 (rIL-2), as confirmed in this case by prompt lymphoma regression after regional rIL-2 perfusion of a cutaneous lesion and by an impressive overall response to systemic rIL-2 treatment. Despite the very low dose of rIL-2, 600,000 IU/24 h as a continuous i.v. infusion, systemic treatment was complicated by generalized capillary leakage and life-threatening unilateral drowning of the lymphoma-infiltrated left lung.

T cell retargeting using bispecific monoclonal antibodies in a rat colon carcinoma model. II. Syngeneic colon carcinoma CC531 is efficiently killed by retargeted cytotoxic T lymphocytes in vitro despite limited lysis in 51Cr release assays.

We have previously described the generation of bispecific anti-TCR*anti-tumor mAb, intended for in vivo analysis of T cell retargeting in a syngeneic rat colon carcinoma model. Colon carcinoma CC531 proved to be markedly resistant to lysis by polyclonally activated, retargeted rat T lymphocytes, if measured in short term or overnight prolonged 51Cr release assays. Using cocultivation, we have now focused on another, biologically more relevant aspect of retargeted interaction: the effect on the capacity of CC531 tumor cells to survive and grow. Tumor neutralization was scored after 3 days of coculture, using a tetrazolium salt to quantify viable adherent tumor cells. Compared to 51Cr release assays, we found cocultivation to be more sensitive and more informative, as it revealed tumor cell killing at low E:T ratios, synergism of bispecific antibodies and exogenous IL-2, and free bispecific antibody-dependent recycling of effector cells. Apart from providing valuable information for future in vivo studies in this model, these data support the notion of tumor neutralization as a useful alternative for 51Cr release assays.