Chromosome aberrations of human small cell lung cancer induced by a new 111In-bleomycin complex

Squamous cell cancer cell lines: sensitivity to bleomycin and suitability for animal xenograft studies

Bleomycin (BLM) is a natural antibiotic, toxic to dividing cells (G2/M-phase), also proven effective in squamous cell carcinomas (SCC). We have clinically shown that a short-range beta-emitting radionuclide combined to bleomycin (In-111-BLMC) is a tumor-targeting agent in SCCs. With higher radionuclide activities it may be possible to develop a more effective agent, to be tested in animal studies. Using a 96-well clonogenic assay we investigated three SCC cell lines, grown in our own laboratory. IC20, IC50 and IC90 values for BLM were determined. The UT-SCC-12A and UT-SCC-12B cells were originated from a primary tumor and a metastasis of the same patient. UT-SCC-12A cells were also inoculated subcutaneously into nude mice and the tumor growth was analysed. The IC50 value for UT-SCC-19A cell line was 4.0 +/- 1.3 nM. UT-SCC-12A and UT-SCC-12B were both more resistant to BLM; IC50 values were 14.2 +/- 2.8 nM and 13.0 +/- 1.1 nM, respectively. Within 35 days the weight of nude mice increased 2.8 +/- 0.6g. At 25 and 35 days after tumor inoculations the tumor volumes were 111 +/- 51 mm3 and 874 +/- 577 mm3, respectively. The calculated doubling time was 3.86 +/- 0.76 days. SCC cell lines demonstrate different sensitivity to BLM. Our SCC tumor xenograft model showed a rapid growth proper for radiochemotherapeutic studies using In-111-BLMC. The uptake of In-111-BLMC in vivo has been directly proportional to proliferation activity, and the tumors with high binding capacity could be predicted from animal model dose calculations.

Imaging and staging of head and neck cancer using a low pH In-111-bleomycin complex

Bleomycin (BLM), a natural antibiotic toxic to dividing cells has been used for treatment of several forms of cancer. BLM has been labelled with various cations but most have turned out to be unstable in vivo. In-BLM has demonstrated high bone marrow uptake, but by using an In-111-bleomycin complex (BLMC) formed at low pH, the low in vivo stability and high bone marrow uptake can be avoided. Our premise is to combine radiotherapy and chemotherapy by using radionuclide-BLMC. In this study we used In-111-A'2a-c-BLMC in 28 head and neck cancer patients. Scintigraphic findings were compared to those of surgery, pre-operative radiology and proliferation markers. The injected patient activity was approximately 85 MBq, 100 MBq/mg. The half-life of In-111 activity in serum varied from 1.5 to 3.1 h, and in urine from 1.4 to 3.7 h. More than 95% of the urine activity was excreted within 24 h. From biopsies obtained from surgical specimens of 22 patients the absolute uptakes in tumour tissues varied between 0.10 and 0.95 x 10(-3)% ID/g. Uptakes in normal tissues varied from 0.01 to 0.32 x 10(-3)% ID/g, and were always lower than in malignant tissues of the same patients. All patients were examined on the injection day with ultrasonography of the neck. Using In-111-BLMC we missed small metastatic lymph nodes (< 1 cm) in 2 patients, but there were no false positive findings. The critical organ from the dosimetric point of view was the kidney. The absorbed radiation doses with these injected activities were 19 mGy in liver, 75 mGy in kidney and 1.0 mGy in whole body (5 h mean residence time). Our results indicate that In-111-BLMC targets head and neck cancer, and identifies metastatic spread. It could possibly be applied with higher activities for adjuvant Auger-electron therapy of head and neck cancer.