A new 111In-bleomycin complex for tumor imaging: preparation, stability, and distribution in glioma-bearing mice

Indium-111-bleomycin complex in squamous cell cancer xenograft tumors of nude mice

INTRODUCTION

Labeling of bleomycin with Auger-emitter Indium-111 increases cytotoxicity in squamous cell cancer (SCC) cell lines, as we have reported earlier. In this study, we investigated whether (111)In- BLMC is toxic and effective in vivo among SCC-xenografted mice. The influence of (111)InBLMC on the squamous cell carcinoma cell cycle stimulated interest.

MATERIALS AND METHODS

In an animal experiment, 10 SCC-xenografted mice were used, two for demonstrating targeting in gamma-camera images, eight for intraperitoneally receiving NaCl, BLM, or (111)InBLMC as therapy. After a 2-week follow-up, the tumors were analyzed for proliferation (mitoses, Ki-67). DNA flow cytometric analysis was carried out from tumor samples and three UT-SCC cell lines.

RESULTS

Tumors were observed on gamma-camera images in xenografted mice after a (111)InBLMC injection. The UT-SCC-19A-xenografted mouse had a T/non-T uptake of 7.54 at 4 hours after the injection. At the end of the therapeutic trial, the mice were alive. In spite of a small number of animals, our findings indicate that BLM and (111)InBLMC seem to be more effective than NaCl in reducing tumor size. The proliferative activity was strong in BLM and in (111)InBLMC groups, indicating regrowth of the tumors. In DNA analysis, the percentages of cells in the G2/M-phases increased after exposure to BLM and particularly to (111)InBLMC in all three cell lines.

CONCLUSIONS

The effect of BLM is preserved after the adding of Auger-emitter In-111. Tumor-seeking (111)InBLMC can be administered safely at tumor-decreasing concentrations in xenograft head and neck cancers. To demonstrate the antitumor effect of (111)InBLMC, the experiments should be extended to include a larger number of mice. BLM, and especially (111)InBLMC, seems to induce alteration in the cell cycle by producing a G2/M block. The verification of the result requires repeated in vitro experiments.

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.

Indium-111 bleomycin complex for radiochemotherapy of head and neck cancer--dosimetric and biokinetic aspects

Bleomycin (BLM) is used for the treatment of head and neck cancer. In order to improve the effectiveness of this chemotherapeutic drug, BLM was combined with indium-111. A complex of these agents (111In-BLMC), formed at low pH, was injected intravenously into ten head and neck cancer patients in escalating activities of 75, 175 and 375 MBq. The internally delivered dose to the tumours varied from 0.20 to 2.73 mGy at 75 MBq, from 0.33 to 2.51 mGy at 175 MBq, and from 0.87 to 31.3 mGy at the 375 MBq activity level. Uptake of radioactivity was 0.45+/-0.24x10(-3)% ID/g in primary tumours and 0. 52+/-0.20x10(-3)% ID/g in metastases (at 48 h). Tumour volumes varied from 0.51 to 49.0 cm3. The radioactivity half-lives in the tumours were 30+/-7 h. The activity distribution and penetration into tumour tissue were not affected by increasing the injected activity. There was a positive correlation between BLMC uptake and Ki-67/Mib activity as well as number of mitoses in tumour tissue. These data indicate that 111In-BLMC has potential as a radiochemotherapeutic agent in head and neck cancer and that adjuvant Auger-electron therapy is possible using 114mIn-labelled BLMC.

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

A new 111Indium labeled bleomycin complex (111In-BLMC) was prepared and found to be effective for tumor imaging and therapy both in mouse glioma and human small cell lung cancer (SCLC) cells. Chromosome aberrations were studied in human SCLC cells to explore its mechanisms of killing cancer cells. SCLC cells (N417) were exposed to 111In-BLMC, BLM, or 111InCl3 (for control) for 1 hour, treated with colcemid, and chromosomal changes were analyzed. A dramatic increase in chromatic gaps, breaks, chromosome breaks, double minutes, rings, triradii, quadriradii, and chromosome stickiness were observed in the cells treated by 111In-BLMC compared to BLM or 111InCl3. These results indicated that 111In-BLMC has therapeutic potential for combination chemo-radiotherapy of cancer (e.g., by Auger electrons and local energy deposition).

Distribution of111 in-bleomycin complex in small cell lung cancer cells by autoradiography

The distribution of 111In-bleomycin Complex (111In-BLMC) in small cell lung cancer (SCLC) cells was studied by autoradiography. SCLC cells were exposed to 111In-BLMC and 111Indium chloride (111InCl3) for 1 hour, 3 hours, and 4 hours; washed with fresh medium; and spread on slides. The slides were smeared with NTB2 (NTB3) emulsion by wet or dry-mount technique and exposed 3 to 15 days. 111In-BLMC was found to localize in the cell nucleus and nuclear membrane (78.3%); 111InCl3 located mainly in the cytoplasm (52.3%). This distribution of labeled BLM may explain the mechanism of killing SCLC cells by 111In-BLMC.

Enhanced killing of human small cell lung cancer by hyperthermia and indium-111-bleomycin complex

Indium-111-bleomycin complex (111In-BLMC) is a radiopharmaceutical agent that produces tumor regression in mouse glioma in vivo and kills human small cell lung cancer (SCLC) cells in vitro. The interaction between hyperthermia and 111In-BLMC against human SCLC (N417) cells was studied for bleomycin (BLM) (15 micrograms/ml) or 111In-BLMC (40-50 microCi carried by 15 micrograms BLM/ml) for 5 min or 1.5, 2, or 4 hr at 37 degrees C or 43 degrees C exposures. Cell survival was determined by colony formation in soft agarose. There was a synergistic effect for 111In-BLMC and hyperthermia for cell killing. At 37 degrees C, the percent survival of N417 cells for BLM alone was 25.9%, and for 111In-BLMC it was 13.2%; at 43 degrees C, survival was 5.3% for BLM alone and 1.2% for 111In-BLMC by a 4 hr treatment. Effectiveness was greater when 111In-BLMC was combined with hyperthermia.

Killing lung cancer cells at cell-cycle phase by a new indium-111-bleomycin complex

The efficacy of killing small cell lung cancer (SCLC) cells at the G1, S, and G2-M phase of the cell-cycle by a new 111In-bleomycin complex (111In-BLMC) was investigated. SCLC cells (N417, H526, H209) were synchronized by double thymidine block and assessed by DNA content with flow cytometry, and the period for the maximal accumulation of cells in S, G1, or G2-M phase was determined. Cells in different cell cycle phases were exposed to 0.9% NaCl, BLM, or 111In-BLMC for 1 hour and observed for colony formation. The survival of H526 cells treated with 111In-BLMC was 71% (for enriched S phase), 46% (G1), and 31% (G2-M). For N417 cells, it was 25% (S), 20% (G1), and 8% (G2-M) for 111In-BLMC and 18% (S), 33% (G1), and 10% (G2-M) for BLM. These results indicated that SCLC cells in G2-M were most sensitive and those in S phase were least sensitive to 111In-BLMC; cells in G1 phase were the least sensitive to BLM.

Killing of human lung cancer cells using a new [111In]bleomycin complex [111In]BLMC

The ability of a [111In]bleomycin complex [( 111In]BLMC) to kill five cell lines of human lung cancer (small cell lung cancer) was investigated. Cells were exposed to either 0.9% NaCl, [111In]Cl3, BLM, [111In]BLMC, nonradioactive InCl3, or In-BLMC for 60 minutes, plated in soft agarose, and assessed for colony formation. [111In]BLMC (40-200 microCi carried by 15-25 micrograms BLM/ml) was more cytotoxic than BLM (15-25 micrograms BLM/ml) by a factor of 1.6-5.3 for five cell lines. The percent survival of N417 cells was 28.4 for [111In]BLMC (40 microCi/15 micrograms BLM/ml) and 54.3 for BLM (15 micrograms/ml); 1.9 for [111In]BLMC (200 microCi/25 micrograms BLM/ml), and 10.0 for BLM (25 micrograms/ml). 111InCl3 (200 microCi/ml) and nonradioactive InCl3 failed to inhibit colony formation. The new [111In]BLMC may be useful for therapy of some lung cancer patients.

Indium 111-A-bleomycin--a new tracer for imaging orofacial neoplasms

Forty-six patients with maxillofacial squamous cell cancer of variable keratinization underwent radioisotope diagnosis using Indium 111-A-bleomycin. This new technique was applied to expand the battery of diagnostic tools available for detecting maxillofacial neoplasms. Its high specificity (100%) and sensitivity (96%) make it well suited for detection of both local and distant recurrences as well as tumor regrowth. Preliminary whole body retention measurements also indicate that this technique looks promising for potential therapeutic use.

A new 111In-bleomycin complex for combined radiotherapy and chemotherapy

Six days after tumor transplantation three daily intraperitoneal doses of 0.9% NaCl, bleomycin (BLM), or a new 111In-bleomycin complex (BLMC, 15 microCi/g body weight) were administered to glioma-bearing mice. After therapy, tumors in mice treated with 111In-BLMC were smaller than those treated with BLM. Sixteen days after the first injection tumor size for 111In-BLMC-treated mice was 560 (240-1,030) mm3, 1,980 (1,400-3,290) mm3 for BLM (P less than 0.025), and 4,830 (2,580-9,180) mm3 for NaCl (0.1 less than P less than 0.2). Thirteen days after tumor transplantation glioma-bearing mice received single intratumor injection of 0.9% NaCl, BLM, or 111In-BLMC (1.5 mCi, carried by 0.5 mg BLM/g tumor weight). The average tumor size for 111In-BLMC was smaller than that for BLM by a factor of 2.5-3.7. Host weights for these two groups were similar, and morphologic abnormalities were not found in kidney or liver.

A new tumor imaging agent--111In-bleomycin complex. Comparison with 67Ga-citrate and 57Co-bleomycin in tumor-bearing animals

We have found a new 111In-bleomycin complex (BLMC), which has high affinity to tumor, does not bind to transferrin and is stable in vivo. Distribution in animals bearing glioma, hepatoma, or mammary adenocarcinoma at 48 hours showed: the ratios of tumor to blood, brain, heart, lung, liver, pancreas, stomach, and femur were 1.4-22.4 times as high for 111In-BLMC as for 67Ga-citrate. In mammary adenocarcinoma, 111In-BLMC bound more to viable and 57Co-Bleomycin (BLM) more to necrotic tumor. In viable tumor, the concentration of 111In-BLMC was similar to that of 57Co-BLM. The ratios of tumor to stomach and pancreas were higher, to blood, brain, muscle, heart, and femur were lower for 111In-BLMC than those for 57Co-BLM. The ratios of tumor to lung, liver, spleen, skin, and kidney were similar for the two compounds. Tumors were imaged more distinctly with the new 111In-BLMC and 57Co-BLM than with 67Ga-citrate. 111In-BLMC is promising for tumor imaging.