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Biomedical subjects

Kyra A Gelderman

Publications and source records attributed to Kyra A Gelderman.

5 recordsLinked to original sources
PubMed2004

Tumor-specific inhibition of membrane-bound complement regulatory protein Crry with bispecific monoclonal antibodies prevents tumor outgrowth in a rat colorectal cancer lung metastases model.

Membrane-bound complement regulatory proteins (mCRP) inhibit complement-mediated tumor cell eradication in vitro and in vivo. Immunotherapy of cancer with monoclonal antibodies (mAbs) that activate complement might be hampered by expression of mCRP on tumor cells. An important strategy to improve mAb immunotherapy can be blocking or overwhelming mCRP at the tumor cells surface in a tumor-specific manner. In our study, we investigated the feasibility of this approach in vivo using bispecific mAbs (bi-mAbs). This study, performed in a syngeneic lung metastases model of rat (WAG/Rij) colorectal cancer, showed that modulation of mCRP on tumor cells resulted in significantly decreased tumor outgrowth. Opsonization of tumor cells with a bi-mAb directed against a tumor-associated antigen and rat mCRP Crry (MG4(2a)*5I2) almost completely prevented the outgrowth of lung tumors (0-7 tumors/rat; n = 17). Opsonization with mAb-cobra venom factor conjugates significantly reduced the number of lung tumors (23-59 tumors; n = 12) compared with the unconjugated MG4(2a) (175-246 tumors; n = 17; P = 0.008 and 0.014, respectively). The effect of MG4(2a)*5I2 was shown to be caused by increased complement activation due to inhibition of Crry. Moreover, prophylactic treatment with MG4(2a)*5I2 or MG4(2a) showed comparable results (3-24 and 215-472 tumors, P = 0.02; n = 6) as observed with pre-opsonized tumor cells without noticeable side effects, despite binding of MG4(2a)*5I2 to endothelium and leukocytes. These results demonstrate that Crry inhibits complement-mediated tumor cell eradication by immunotherapeutic mAbs and show that tumor-specific inhibition of complement regulatory proteins using bi-mAbs can significantly improve mAb-mediated immunotherapy.

Adenocarcinoma↗
PubMed2004

Beta-glucan enhanced killing of renal cell carcinoma micrometastases by monoclonal antibody G250 directed complement activation.

Metastases from renal cell carcinomas (RCC) are resistant to radiation and chemotherapy but are relatively immunogenic. We have investigated the possibility to eliminate human RCC micrometastases using MAb G250. G250 penetrates human micrometastases completely in a spheroid model and induces complement deposition rapidly on the outmost cell layers. However, complement dependent cytotoxicity (CDC) was barely detected using either (51)chromium release assays or confocal microscopy, due to relatively low expression of the G250 antigen and the effect of membrane bound complement regulatory proteins. Addition of blocking anti-CD59 MAbs enhanced formation of C5b-9 and consequently complement mediated lysis (13%). Complement assisted cellular cytotoxicity (CACC) was not detectable, although the iC3b ligand and CR3 receptor were present on respectively target and effector cells. Addition of soluble beta-glucan induced the killing of MAb and iC3b opsonized spheroids by effector cells (6-21%). Despite a lower affinity for G250 antigen, a bispecific anti-G250*anti-CD55 MAb enhanced cell killing in spheroids comparable to the parental G250 MAb. Our results suggest that complement-activating G250 in combination with anti-mCRP MAbs is able to kill human RCC cells in micrometastasis in vitro. For CACC the presence of CR3-priming beta-glucan seems to be obligatory. In vivo, bi-MAb may be more effective as therapeutic agent due to its increased C5a generating properties.

Antibodies, Monoclonal↗
PubMed2002

Enhancement of the complement activating capacity of 17-1A mAb to overcome the effect of membrane-bound complement regulatory proteins on colorectal carcinoma.

Adjuvant immunotherapy with 17-1A mAb directed against colorectal carcinoma is found to be effective in patients. However, 52 % of the patients treated with mAb 17-1A showed recurrence within 7 years. This high recurrence rate might be due to inhibition of complement activation by membrane-bound complement regulatory proteins (mCRP). The effect of these complement regulatory proteins might be reduced by blocking mCRP, or be overcome by activating more complement at the tumor cell membrane. In this study the complement-activating capacity of the 17-1A mAb was enlarged by conjugating it to cobra venom factor (CVF) or C3b. The most important C3 regulatory protein, CD55, was blocked using a bispecific mAb directed against the 17-1A / Ep-CAM antigen and CD55. Up to a 13-fold increase in C3 deposition was observed due to 17-1A-CVF and 17-1A-C3b, as compared to 17-1A. CD55 was shown to partly inhibit complement activation by these conjugates. The effect of the bispecific anti-17-1A / Ep-CAM*anti-CD55 mAb was compared with 17-1A conjugates with CVF or C3, and bispecific mAb were shown to be equally or more efficient in complement activation than the 17-1A-CVF or 17-1A-C3b conjugates. Therefore, 17-1A conjugates and anti-17-1A / EpCAM*anti-CD55 bispecific mAb may be promising immunotherapeutic agents for patients with colorectal cancer.

Animals↗
PubMed2002

The inhibitory effect of CD46, CD55, and CD59 on complement activation after immunotherapeutic treatment of cervical carcinoma cells with monoclonal antibodies or bispecific monoclonal antibodies.

The role of membrane-bound complement regulatory proteins (mCRP) in the protection of tumor cells in vivo against elimination by the immune system is still unknown. In this study the effect of expression of these mCRP by cervical cancer cells was investigated. In situ expression of mCRP was observed on cervical carcinomas, normal cervical epithelial cells, and the surrounding stroma. Deposition of C3 and C5b-9 was sporadically found on the tumor cells and the surrounding stroma. A low expression of CD46 was statistically significantly associated with deposition of C3. Comparable expression patterns were shown on primary cervical tumor cell suspensions. A relatively high deposition of C4c was found on these tumor cells, indicating classical pathway activation. Furthermore, it was demonstrated that CD55 and CD59 were the most potent inhibitors of C3 deposition and classical pathway-mediated lysis, respectively, on cervical cancer cell lines. The feasibility of increasing complement activation at the tumor cell membrane surface was demonstrated with an anti-HLA Class I*anti-CD55 bispecific mAb. The potential immunotherapeutic applicability was investigated with both anti-G250*anti-CD55 and anti-Ep-CAM*anti-CD55 bispecific mAbs. An approximate 2-fold increase in C3 deposition, compared with the parental anti-Ep-CAM mAb, was attained with an anti-Ep-CAM*anti-CD55 bispecific mAb when the tumor-associated antigen was expressed in sufficient amounts. These results demonstrate that when tumor-associated antigens are expressed in adequate amounts, bispecific mAbs in vivo may be potent immunotherapeutic agents to enhance an inflammatory reaction at the tumor site.

Antibodies, Bispecific↗