Intravesical administration of indium-111-labelled HMFG2 monoclonal antibody in superficial bladder carcinomas

CAR T cells redirected against tumor-specific antigen glycoforms: can low-sugar antigens guarantee a sweet success?

Immune-based therapies have experienced a pronounced breakthrough in the past decades as they acquired multiple US Food and Drug Administration (FDA) approvals for various indications. To date, six chimeric antigen receptor T cell (CAR-T) therapies have been permitted for the treatment of certain patients with relapsed/refractory hematologic malignancies. However, several clinical trials of solid tumor CAR-T therapies were prematurely terminated, or they reported life-threatening treatment-related damages to healthy tissues. The simultaneous expression of target antigens by healthy organs and tumor cells is partly responsible for such toxicities. Alongside targeting tumor-specific antigens, targeting the aberrantly glycosylated glycoforms of tumor-associated antigens can also minimize the off-tumor effects of CAR-T therapies. Tn, T, and sialyl-Tn antigens have been reported to be involved in tumor progression and metastasis, and their expression results from the dysregulation of a series of glycosyltransferases and the endoplasmic reticulum protein chaperone, Cosmc. Moreover, these glycoforms have been associated with various types of cancers, including prostate, breast, colon, gastric, and lung cancers. Here, we discuss how underglycosylated antigens emerge and then detail the latest advances in the development of CAR-T-based immunotherapies that target some of such antigens.

Intracavitary radioimmunotherapy to treat solid tumors

Radioimmunotherapy (RIT) potentially is an attractive treatment for radiosensitive early-stage solid tumors and as an adjuvant to cytoreductive surgery. Topical administration of RIT may improve the efficacy because higher local concentrations are achieved. We reviewed the results of locally applied radiolabeled monoclonal antibodies for the treatment of solid tumors. Intracavitary RIT in patients with ovarian cancer and glioma showed improved targeting after local administration, as compared to the intravenous administration. In addition, various studies showed the feasibility of locally applied RIT in these patients. In studies that included patients with small-volume disease, adjuvant RIT in ovarian cancer and glioma showed to be at least as effective as standard therapy. The information about RIT for peritoneal carcinomatosis of colorectal origin is scarce, while results from preclinical data are promising. RIT may be applied for other, relatively unexplored indications. Studies on the application of radiolabeled antibodies in early urothelial cell cancer have been performed, showing that intracavitary RIT may hold a promise. Moreover, in patients with malignant pleural mesothelioma or malignant pleural effusion, RIT may play a role in the palliative treatment. Intracavitary RIT limits toxicity and improves tumor targeting. RIT is more effective in patients with small-volume disease of solid cancers. RIT may have potential for palliation in patients with malignant pleural mesothelioma or malignant pleural effusion. The future of RIT may, therefore, not only be in the inclusion in contemporary multimodality treatment, but also in the expansion to palliative treatment.

Synergistic chemosensitization and inhibition of tumor growth and metastasis by adenovirus-mediated P53 gene transfer in human bladder cancer model

OBJECTIVES

To determine whether an adenovirus-mediated p53 gene (Ad5CMV-p53) transfer enhances cisplatin cytotoxicity in vitro and whether Ad5CMV-p53 and cisplatin synergistically inhibit growth and metastasis in vivo using human bladder cancer KoTCC-1 cells.

METHODS

MTT assays and DNA fragmentation assays were used to examine the effects of treatment with Ad5CMV-p53 and/or cisplatin on growth inhibition and induction of apoptosis, respectively, in KoTCC-1 cells. The efficacies of combined Ad5CMV-p53 and/or cisplatin therapy against growth and metastasis of KoTCC-1 tumors were assessed using subcutaneous and orthotopic tumor cell injection models.

RESULTS

Ad5CMV-p53 substantially enhanced cisplatin chemosensitivity in a dose-dependent manner, reducing the median IC(50) by more than 50%. Characteristic apoptotic DNA laddering was induced by the combination of sublethal doses of Ad5CMV-p53 and cisplatin, but not by either agent alone. Furthermore, combined Ad5CMV-p53 and cisplatin therapy synergistically inhibited growth of subcutaneous KoTCC-1 tumors and the incidence of metastasis after orthotopic injection.

CONCLUSIONS

These findings illustrate that combined treatment with Ad5CMV-p53 and cisplatin could be an attractive strategy for inhibiting progression of bladder cancer through effective induction of apoptosis.

Targeting superficial bladder cancer by the intravesical administration of copper-67-labeled anti-MUC1 mucin monoclonal antibody C595

PURPOSE

More effective intravesical agents are required to limit the recurrence and progression of superficial bladder cancer. This study assessed the ability of copper-67 ((67)Cu)-C595 murine antimucin monoclonal antibody to bind selectively to superficial bladder tumors when administered intravesically, with a view to its development for therapy.

PATIENTS AND METHODS

Approximately 20 MBq of (67)Cu-C595 monoclonal antibody was administered intravesically to 16 patients with a clinical indication of superficial bladder cancer. After 1 hour, the bladder was drained and irrigated. Tissue uptake was assessed by imaging and by the assay of tumor and normal tissues obtained by endoscopic resection.

RESULTS

Tumor was correctly identified in the images of 12 of 15 patients who were subsequently found to have tumors. Assay of biopsy samples at 2 hours showed a mean tumor uptake of 59.4% of the injected dose per kilogram (SD = 48.0), with a tumor-to-normal tissue ratio of 14.6:1 (SD = 20). After 24 hours (n = 5), this decreased to 4.3% of the injected dose per kilogram (SD = 2.9), with a tumor-to-normal tissue ratio of 1.8:1 (SD = 0.8).

CONCLUSION

This study indicates a promising method for the treatment of superficial bladder cancer. Although the mean initial tumor uptake was high, effective therapy of bladder tumors will require an increased retention of the cytotoxic radionuclide in tumor tissue.

Preclinical evaluation of copper-67 labelled anti-MUC1 mucin antibody C595 for therapeutic use in bladder cancer

Transitional cell carcinoma of the bladder is the fifth commonest cause of death from cancer in men in the United Kingdom. Most patients present early with superficial disease, though with current treatment up to 20% progress to invasive disease, which has a poor prognosis. Better local treatments are required to limit this tumour progression. The ease of access to the bladder via a catheter provides the ideal opportunity for antibody (Ab) targeted therapy. We have previously shown that indium-111 labelled anti-MUC1 mucin Ab C595 selectively localises to bladder tumours after intravesical administration. We have selected copper-67 as an alternative radiolabel with suitable physical characteristics for radioimmunotherapy. This communication demonstrates that C595 can be reproducibly labelled with 67Cu and that the radioimmunoconjugate is both stable and maintains high immunoreactivity. Pilot studies on cystectomy specimens in a novel ex vivo system and in one patient confirmed the ability of this conjugate to localise to tumour after intravesical administration. On the basis of these studies we are now in a position to study the intravesical administration of 67Cu-labelled C595 in patients with bladder cancer with a view to a therapeutic trial.

Toxicity of ribosome-inactivating proteins-containing immunotoxins to a human bladder carcinoma cell line

Immunotoxins were prepared by linking the type 1 ribosome-inactivating proteins (RIP) momordin I, pokeweed antiviral protein from seeds (PAP-S) and saporin-S6 to the 48-127 monoclonal antibody (MAb) recognising a glycoprotein (gp54) expressed on all human bladder tumours tested and on human bladder carcinoma cell lines, in particular on the T24 cell line. T24 cells required a 2 hr contact with immunotoxins to ensure binding and endocytosis. A time course of exposure, followed by further incubation without the immunotoxins, showed that maximum inhibition of protein synthesis by T24 cells was reached after 2 hr of contact followed by 3 days without the immunotoxins. Under optimal conditions, 48-127/RIP immunotoxins at nanomolar concentrations inhibited by 50% protein synthesis of target T24 cells. No toxicity was observed if (i) target cells were treated with non-conjugated RIP, (ii) target cells were treated with momordin I- or PAP-S-containing immunotoxins made with an irrelevant antibody and (iii) a non-target cell line was treated with the same 2 RIP conjugated to 48-127 antibody. The in vitro selective toxicity of these immunotoxins encourages further studies in view of a possible use in clinical trials for the local therapy of human bladder carcinomas.

Characterisation of the anti-bladder-cancer monoclonal antibody BLCA-8: identification of its antigen as a neutral glycolipid

A monoclonal antibody, BLCA-8, was raised against the human bladder cancer cell line, UCRU-BL-17CL. By flow cytometry and immunoperoxidase staining, this antibody was found to possess high specificity for bladder tumours, some reactivity with fetal tissues, and no reactivity with normal bladder, or any normal or malignant tissue. This high specificity and the stability of the antigen to the urinary environment suggest that BLCA-8 may have potential for use as an anti-bladder-cancer therapeutic agent. By thin-layer chromatography and autoradiography, BLCA-8 was found to bind four components within the neutral lipid fraction of a bladder cancer cell line, UCRU-BL-17/23 alpha. These components had RF values of 0.22, 0.16/0.15 (doublet), 0.12 and 0.08, and migrated below globoside, indicating the presence of more than four sugars. By enzyme-linked immunosorbent assay and thin-layer chromatography it was found that the binding of BLCA-8 to the lipid extract was increased by both mild alkaline hydrolysis and enzymatic treatments, indicating that adjacent phospholipids and glycolipids interfere with the accessibility of the antibody-binding site. Full biochemical characterisation of the BLCA-8 antigen is currently underway.

Targeting of bladder cancer with monoclonal antibody NCRC48--a possible approach for intravesical therapy

OBJECTIVE

To determine the localization of the anti-MUC1 mucin monoclonal antibody (mAb) NCRC48 to bladder cancer following intravesical administration.

PATIENTS AND METHODS

mAb NCRC48 (330-500 micrograms) radiolabelled with 111indium (11-17 MBq) was administered intravesically to 12 unselected patients with radiological evidence of bladder cancer. Tumour localization was assessed by gamma-camera imaging and by tissue biodistribution studies on biopsies obtained at cystoscopy at about 2 or 24 h after the procedure. After 24 h, whole blood radioactivity was measured and 3 weeks after the procedure the serum level of human anti-mouse antibodies was estimated using an ELISA method.

RESULTS

Eleven patients had tumours confirmed at cystoscopy (grades 1-3, stages pTa-pT2). The mean uptake of NCRC48 by tumour and by normal urothelium (expressed as the percentage of the instilled dose/g x 10(3) +/- SD) at 2 h was 3.42 +/- 3.68 and 0.41 +/- 0.77 (P < 0.05). After 24 h, the values for tumour and normal urothelium were 1.17 +/- 1.18 and 0.17 +/- 0.11, respectively. Areas of increased activity on the scintigrams were consistent with the position of the tumours at cystoscopy. No radioactivity was detected in blood at 24 h and there was no evidence of a human anti-mouse antibody response.

CONCLUSION

The MUC1 mucin may be a suitable antigen to study the potential of therapeutic strategies based on monoclonal antibody targeting of superficial bladder cancer and may allow the development of more effective agents in the treatment of this condition.

Recent developments in radioimmunotherapy

With the advent of monoclonal antibody techniques, there has been renewed interest in RIT as a treatment modality in patients with a variety of tumour types. There has been a considerable research effort to increase understanding of the scientific basis of such therapy at all levels. Antibody, chelator and radioisotope factors are all the subject of research aimed at producing a potent effector system capable of maximal target cell kill with acceptable normal tissue toxicity. Improved knowledge of the host and tumour factors which limit access to the target cell offers the possibility of optimizing targeting and increasing the therapeutic index. Target cell factors that influence response to low dose rate RIT have been elucidated and provide an opportunity to integrate the treatment modality into radical therapy regimens. A number of Phase I and II trials have now been performed in various tumour types. The results have been promising but, as yet, the prospect of radical RIT remains a research goal. Before it can be achieved it will be necessary to improve specific tumour cell targeting and to increase both the initial dose rates and the total dose delivered to tumour deposits. Until such time, it is likely that RIT will be incorporated into multimodality protocols to deliver a moderate (10-20 Gy) tumour boost, or in an adjuvant setting in patients with minimal residual disease.