Immunotherapy of colorectal cancer using bispecific antibodies
Immunotherapy of colorectal cancer using bispecific antibodies
In clinical trials a low affinity monclonal antibody (17.1A) to Ep-CAM, a tumour associated antigen found on colorectal cancer cells, has demonstrated a significant survival advantage as adjuvant therapy in Duke’s C colorectal carcinoma.
Bispecific antibodies (BsAbb) are single antibody molecules engineered with two different antigen specificities. In this work I have constructed a F(ab’)2 BsAb from a higher (40x greater than 17.1A) affinity antibody (323A3) to Ep-CAM. The other arm of the BsAb binds to CD3 on cytotoxic T Lymphcyte (CTL), thus targeting them to kill tumour cells. Using CD3 allows recruitment of a large range of CTLs irrespective of their antigen specificity. In vitro this BsAb, 323A3xCD3, successfully killed human colorectal cancer cells (HT-29) and transfected murine tumours bearing human Ep-CAM.
Using the same BsAb, successful immunotherapy in vivo has been achieved in an immunocompetent mouse tumour model. Groups of C57/Blk mice were given B16C215 syngeneic tumour cells expressing human E-CAM on their surface. To model minimal residual disease tumour was given intravenously and animals were either called on day 21 and pulmonary surface tumour was given intravenously and animals were either culled on day 21 and pulmonary surface metastases counted, or survival recorded. To model local growth, tumour was given subcutaneously and tumour appearance, growth survival were recorded. In both these models BsAb was given for 10 days starting 24 hours after tumour administration.
With intravenous tumour, BsAb treatment reduced mean pulmonary metastases: [4.6 cf. 208.5 (control); p<0.001] and prolonged survival [median 56 days cf. 32 (control); p<0.01]; low affinity 17.1A IgG and high affinity 323A3 IgG had no significant effect. In the local tumour model, 323A3xCD3 therapy retarded tumour appearance [median 25.5 days cf. 16 (control); p<0.0001] and growth [mean volume 51.6mm3 cf. 1036mm3 (control) on day 18; p<0.01]; and prolonged survival [median 37 days cf. 23 (control); p<0.0001]; 17.1A IgG and 323A3 IgG had no significant effect.
University of Southampton
Safranek, Peter Michael
24ad5d0b-c1a3-4dfb-830f-d863852481e8
2005
Safranek, Peter Michael
24ad5d0b-c1a3-4dfb-830f-d863852481e8
Safranek, Peter Michael
(2005)
Immunotherapy of colorectal cancer using bispecific antibodies.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
In clinical trials a low affinity monclonal antibody (17.1A) to Ep-CAM, a tumour associated antigen found on colorectal cancer cells, has demonstrated a significant survival advantage as adjuvant therapy in Duke’s C colorectal carcinoma.
Bispecific antibodies (BsAbb) are single antibody molecules engineered with two different antigen specificities. In this work I have constructed a F(ab’)2 BsAb from a higher (40x greater than 17.1A) affinity antibody (323A3) to Ep-CAM. The other arm of the BsAb binds to CD3 on cytotoxic T Lymphcyte (CTL), thus targeting them to kill tumour cells. Using CD3 allows recruitment of a large range of CTLs irrespective of their antigen specificity. In vitro this BsAb, 323A3xCD3, successfully killed human colorectal cancer cells (HT-29) and transfected murine tumours bearing human Ep-CAM.
Using the same BsAb, successful immunotherapy in vivo has been achieved in an immunocompetent mouse tumour model. Groups of C57/Blk mice were given B16C215 syngeneic tumour cells expressing human E-CAM on their surface. To model minimal residual disease tumour was given intravenously and animals were either called on day 21 and pulmonary surface tumour was given intravenously and animals were either culled on day 21 and pulmonary surface metastases counted, or survival recorded. To model local growth, tumour was given subcutaneously and tumour appearance, growth survival were recorded. In both these models BsAb was given for 10 days starting 24 hours after tumour administration.
With intravenous tumour, BsAb treatment reduced mean pulmonary metastases: [4.6 cf. 208.5 (control); p<0.001] and prolonged survival [median 56 days cf. 32 (control); p<0.01]; low affinity 17.1A IgG and high affinity 323A3 IgG had no significant effect. In the local tumour model, 323A3xCD3 therapy retarded tumour appearance [median 25.5 days cf. 16 (control); p<0.0001] and growth [mean volume 51.6mm3 cf. 1036mm3 (control) on day 18; p<0.01]; and prolonged survival [median 37 days cf. 23 (control); p<0.0001]; 17.1A IgG and 323A3 IgG had no significant effect.
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Published date: 2005
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Local EPrints ID: 465618
URI: http://eprints.soton.ac.uk/id/eprint/465618
PURE UUID: cfe17443-6b56-46d7-a6fd-bd487e8836bc
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Date deposited: 05 Jul 2022 02:04
Last modified: 23 Jul 2022 02:16
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Author:
Peter Michael Safranek
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