Phase I Trial of Technetium [Leu13] Bombesin as Cancer Seeking Agent: Possible Scintigraphic Guide for Surgery?

Aims and Background

Bombesin-like neuropeptides work as neurotransmitters and growth factors at the same time. Several human cancers show overexpression of three receptors for mammalian counterparts of amphibian bombesins (ABNs), ie gastrin-releasing peptide (GRP), neuromedin B (NMB) and possibly another peptide. ABNs in turn are able to bind to mammalian and human receptors in vitro, and it is therefore interesting to study radioisotope-labeled bombesin (BN) and BN-like peptides as cancer seeking agents.

Methods and Study Design

Starting from the amino acid sequence of [Leu13] ABN, the Demokritos Institute has synthesized and labeled with technetium a new BN-like peptide that has the same biological characteristics as the amphibian peptide; changes were made only in the N-terminal part of this tetradecapeptide. After having obtained satisfactory results with 99mTc BN in a preclinical study, we started a phase I trial involving cancer patients as well as normal volunteers in Tomsk. Three normal volunteers, one patient with small cell lung cancer and one patient with primary prostate cancer were studied after iv injection of 185 MBq, corresponding to 0.7 micrograms of 99mTc BN. Dynamic images of the tumors were acquired for 20 mins, followed by SPET. Total body images were acquired in patients and normal volunteers 1 and 3 h after 99mTc BN acquisition. In addition, 99mTc sestamibi scintigraphy was performed in the patient with small cell lung carcinoma.

Results

No relevant side effects were observed. Both tumors were well visualized on early 1-2 mins images with planar as well as tomographic imaging. Total body images showed radioactivity in the liver, kidneys and thyroid gland. The stomach and spleen were never imaged. Radioactivity was found in the urinary bladder 4 mins after injection in the patient with prostate cancer. Three-hour total body scans showed radioactivity in the duodenum. In the patient in whom also 99mTc sestamibi scintigraphy was performed, thyroid uptake was much higher with sestamibi than with 99mTc BN, whereas the uptake of small cell lung carcinoma was higher with 99mTc BN than with sestamibi.

Conclusions

99mTc BN is able to clearly image tumors with BN receptor overexpression. Our first impression is that in the future this radiopharmaceutical may serve as a cancer seeking agent and, due to its high tumoral uptake, also as a radiotracer for radioisotope-guided surgery.

Breast Cancer Takes up 99mTc Bombesin. A Preliminary Report

Background

Several tumors including lung, prostate, ovarian, colon, and exocrine pancreatic cancer show receptors for the amphibian neurotransmitter and growth factor bombesin (BN) and its mammalian counterparts gastrin-releasing peptide and neuromedin B. Also breast cancer has been reported to show such receptors: the presence of BN receptors in primary breast cancer has been demonstrated on cultured cells and by autoradiography on breast tissue samples. Authors who have studied BN receptors in breast cancer do not agree on their frequency in primary cancer, but indicate that 100% of metastatic breast cancers show such receptors.

Methods

We examined three primary breast cancer patients with 99mTc BN and 99mTc sestamibi one week before surgery. One of them showed axillary node invasion. The same acquisition technique was used for breast and chest imaging with both radiopharmaceuticals, whereas total body images were acquired only with 99mTc BN. Also the administered radioactivity was different: 20 mCi of 99mTc sestamibi and 5-8 mCi of 99mTc BN. Dynamic images were acquired for 20 mins after iv injection with the patient in ventral decubitus and the gamma camera positioned in lateral view, as is generally done in Khakhali's prone scintimammography. Anterior chest images were acquired for 30 mins. Prone scintimammography was performed one hour after administration of both tracers. ROIs were drawn on tumors and surrounding breast with the same technique in order to calculate the tumor to breast ratio (T/B). In addition, total body scan was performed one hour and three hours after 99mTc BN administration. All three patients underwent breast conserving surgery with lymphadenectomy. Postoperative pathologic assessment showed the following T and N stages in the three patients: T1bN0, T1cN0. and T1cN1.

Results

All three cancers were imaged with both tracers. The T/B of 99mTc BN was always higher than that of 99mTc sestamibi. Chest uptake was always much higher with 99mTc sestamibi than with 99mTc BN. Comparison between 99mTc BN and 99mTc sestamibi images gave other intriguing results: in the N1 patient both tracers clearly imaged the invaded node, but on the 99mTc BN image the primary tumor was larger than on the 99mTc sestamibi image and the node was smaller. It is known that 99mTc BN is not taken up by vessels and inflammatory tissue. The time activity curves of the two tracers were significantly different in all patients, with an increase in 99mTc BN uptake in the first three to five minutes, followed by a less sharp uprise of the curve, quite similar to a plateau.

Conclusions

Our first impression is that 99mTc BN is a useful breast cancer seeking agent and very promising for lymph node staging.

Chronic idiophatic urticaria and Helicobacter pylori: a specific pattern of gastritis and urticaria remission after Helicobacter pylori eradication

Chronic urticaria (CU) is defined as the occurrence of spontaneous wheals for a duration of more than 6 weeks and is the most frequent skin disease, with prevalence ranging between 15 and 25%, and is a seriously disabling condition, with social isolation and mood changes causing a significant degree of dysfunction and quality of life impairment to many patients. The main clinical features of CU are the repeated occurrence of transient eruptions of pruritic wheals or patchy erythema on the skin that last less than 24 hours and disappear without sequelae. CU is often defined as chronic idiopathic urticaria (CIU) because the causes of CU remain unknown in the great majority (70-95%) of patients. Drugs, food, viruses, alimentary conservative substances or inhalant substances often seem to be involved in determining CIU skin flare. Despite a general agreement that bacteria infections and parasitic infestations can be involved in the pathogenesis of CIU, proven evidence of these relationships is lacking. The aim of the present study is to evaluate the prevalence of Helicobacter pylori (Hp) infection, and the extension and severity of gastritis in a group of CIU patients compared to controls and to evaluate the effectiveness of eradication of Hp on the CIU symptomatology, and the role of Hp infection in pathogenesis of CIU.

Acute intestinal obstruction and NOD2/CARD15 mutations among Italian Crohn's disease patients

Three CARD15 mutations (SNP8, SNP12, SNP13) were significantly associated with CD, however ethnic variations and genotype-phenotype relationships are still to be defined.

AIMS

To evaluate the prevalence of three CARD15 mutations in 91 in-out consecutive CD, 109 Ulcerative Colitis (UC), 101 healthy controls; to examine the genotype-phenotype relationships among italian pts with CD.

MATERIAL AND METHODS

The three mutations were determined by direct sequencing analysis. In CD were evaluated several feature of disease phenotype. Data analysis was performed by using c2 or Fisher Test applying Bonferroni's correction.

RESULTS

The allelic and genotype frequencies of CARD15 mutations were significantly associated to CD. None of controls or UC were homozygotes (OM) or compound heterozigotes (CET). In CD the carriers of at least one mutation were 26/91 (28.6%). The frequencies of simple heterozygotes (ET), CET and OM were: 19/26, 4/26, 3/26 respectively. A significant positive association was found between small bowel location and an acute intestinal obstruction at diagnosis and the carriers of at least one mutation (p = 0.036, OR:0.33 [0.12-0.9] and p = 0.0025, OR:0.125 [0.03-0.5], respectively), particularly with OM and CET genotype (p = 0.005, OR:0.07 [0.01-0.6]). A positive trend between the number of surgery and the carriers of at least one mutation was found, but it didn't reach statistical significance (p = 0.0469, OR:0.3 [0.1-0.96]). No relationship between CARD15 mutations and the other phenotype characteristics was found.

CONCLUSIONS

Our data confirms that CARD15 mutations are significantly associated with CD also in Italian population and with small bowel location (OM and CET genotype). A new positive association was also found between the carriers of at least one mutation and the acute intestinal obstruction at diagnosis.

Synthesis, chemical, radiochemical and radiobiological evaluation of a new 99mTc-labelled bombesin-like peptide

A new pentadecapeptide bombesin analogue was prepared by Fmoc synthesis, purified by HPLC and identified by electron ionization mass spectrometry. The biological activity of the new peptide was tested on isolated human colonic muscle cells and compared to native bombesin. Labelling of the new biomolecule with Tc-99m yielded a single radioactive species which remained stable at room temperature for eight hours. In a binding assay, the radiolabelled peptide showed high affinity for oat-cell carcinoma (Kd = 9.8 nM) and colorectal adenocarcinoma (Kd = 27.2 nM). Biodistribution studies, performed in normal rodents, indicated uptake by organs that normally express bombesin receptors, such as liver, intestines and kidneys. Scintigraphic studies, performed in nude mice transplanted with small cell lung carcinoma and colon cancer cells, showed significant tumor uptake two hours p.i. The new synthetic pentadecapeptide appears to have promise for several malignancies, including oat-cell lung carcinoma, colorectal cancer and gastroenteropancreatic (GEP) tumors.

Role of disease-causing genes in sporadic pancreatic endocrine tumors: MEN1 and VHL

Pancreatic endocrine tumors (PETs) occur in association with multiple endocrine neoplasia type 1 (MEN1) and von Hippel-Lindau (VHL) syndromes caused by germline alterations in MEN1 and VHL, respectively. It is thus expected that these genes will also be altered in a proportion of sporadic PETs. Indeed, MEN1 is altered in about 25% of nonfamilial PETs, although no mutations have been found in VHL. For all clinical subtypes, the frequency of allelic loss on chromosome arm 11q mirrors observed mutational frequencies, with the exception of nonfunctional tumors (NF-PETs), in which mutations have been reported in only 8% of cases. As allelic loss on 11q is the most frequent event found in these neoplasms, this low frequency is somewhat puzzling, particularly in light of the fact that most MEN1-associated PETs are nonfunctioning. To clarify the role of these genes in sporadic PETs, we analyzed 31 sporadic NF-PETs, nine insulinomas, and one VIPoma for alterations in MEN1 and VHL. As somatic mutations were observed in eight (26%) of the NF tumors and in one insulinoma, it would therefore appear unlikely that an additional tumor suppressor gene related to sporadic PET pathogenesis is located on 11q. One insulinoma also had a somatic mutation in VHL, and thus this gene may also be altered in these neoplasms, albeit in a small proportion of cases.

Three months of octreotide treatment decreases gastric acid secretion and argyrophil cell density in patients with Zollinger-Ellison syndrome and antral G-cell hyperfunction

METHODS

The effects of three months of treatment with octreotide on gastric acid hypersecretion induced by hypergastrinaemia were investigated in patients with Zollinger-Ellison syndrome (n = 5) or antral G-cell hyperfunction (n = 4). Gastric acid secretion, fasting plasma gastrin concentrations and clinical findings were examined, and a morphometrical analysis of oxyntic endocrine cells was performed.

RESULTS

Administration of octreotide 100 mcg b.d. subcutaneously significantly decreased the volume density of argyrophil cells (P < 0.05) as well as basal and pentagastrin-stimulated acid secretion (P < 0.05). Although partial or complete loss of inhibition was found in most patients after 3 months, gastrin levels were decreased during the first 2 months of treatment (P < 0.05). Fundic D-cells were not affected by treatment. Positive correlations were observed between volume density of argyrophil cells and basal acid output (r = 0.65); plasma gastrin and basal acid output (r = 0.74); plasma gastrin concentrations and volume density of argyrophil cells (r = 0.80).

CONCLUSION

These results support the important role of the enterochromaffin-like cell in maintaining acid secretion, and indicate a specific role for octreotide in the therapy of gastric acid hypersecretion associated with hypergastrinaemic diseases.

Helicobacter pylori infection in children with antral gastrin cell hyperfunction

Antral gastrin cell hyperfunction (AGCH) is a rare syndrome characterized by persistent hypergastrinemia and important peptic symptoms in the absence of a gastrin-producing tumor. The pathogenesis of AGCH is still unknown and debated. Helicobacter pylori (Hp) infection has been reported as a possible cause of sustained hypergastrinemia. To assess the relevance of Hp infection in pediatric AGCH patients, Hp status, G cell function, acid secretion, and antral G and D cell populations were investigated in six children presenting with gastrointestinal bleeding of unknown origin, sideropenic anemia, and variable abdominal symptoms. All patients had moderate high basal gastrinemia with abnormally increased peak values after meals and elevated values of basal acid output (BAO), maximal acid output (MAO), and pentagastrin-stimulated acid output (PAO). Circulating pepsinogen I was also significantly increased. Three children had Hp infection, as assessed by enzyme-linked immunosorbent assay, urease test, and histology. Endoscopy showed duodenal erosions in three children, with ulcer in two Hp-positive cases. At histology, moderate gastritis was observed only in the three Hp-positive cases. In all patients, quantitative assessment of antral gastrin and somatostatin cells gave significantly elevated G cell counts; D cells were at the lower reference limit and the G/D cell ratio was significantly elevated. These data indicated a diagnosis of AGCH, possibly due to the elevated G/D cell ratio, and suggest HP infection as an overlapping factor complicating the clinical picture in some cases.

Zollinger-Ellison syndrome and antral G-cell hyperfunction in patients with resistant duodenal ulcer disease

We measured basal and pentagastrin-stimulated acid secretion, as well as basal and meal-stimulated plasma gastrin concentration to determine, in 67 patients affected by resistant duodenal ulcer, whether their condition could be related to gastric acid secretion and/or gastrin-related syndromes. We then compared them to 46 duodenal ulcer control patients. The outpatients were investigated consecutively. The resistant duodenal ulcer patients differed from the controls only in their higher complication rates (bleeding or perforation, P < 0.05). We identified five patients in the resistant duodenal ulcer group with Zollinger-Ellison syndrome and 12 with antral G cell hyperfunction, whereas in the control group only one patient was affected by antral G cell hyperfunction. IgG anti-Helicobacter pylori antibodies were positive for the presence of infection in 7 of the hypergastrinaemic patients. When Zollinger-Ellison syndrome or antral G cell hyperfunction were excluded, no differences could be found in gastric acid secretion, or basal and meal-stimulated plasma gastrin levels, between the resistant and control duodenal ulcer patients, except for basal acid hypersecretion (resistant duodenal ulcer 16% vs duodenal ulcer 2% P = 0.0144). In the presence of duodenal ulcer disease resistant to H2-blockers, it is mandatory to measure basal plasma gastrin concentration since it was possible to diagnose the gastrin-related syndromes, Zollinger-Ellison syndrome and antral G cell hyperfunction, in 26% of this group of patients.

Efficacy of long-term therapy with low doses of omeprazole in the control of gastric acid secretion in Zollinger-Ellison syndrome patients

Thirteen patients with Zollinger-Ellison syndrome were investigated: 8 without, and 5 with, previous gastric surgery. After 7-34 months of treatment with famotidine, 8 out of 13 patients were resistant to this drug. Omeprazole 60 mg/day was administered to these 8 patients; after one month, the dose was reduced to 40 mg/day, and after another month to 20 mg/day. Basal acid secretion was inhibited by every dose of omeprazole. The patients were then treated with a low dose (20 mg/day) of omeprazole for a longer period. Periodic clinical and endoscopic assessments, and measurement of basal acid secretion showed the efficacy of this low dose of omeprazole in our Zollinger-Ellison syndrome patients. The drug was discontinued after 12-32 months of omeprazole treatment, and gastric acid recovery was evaluated. Four patients recovered 50% of their 'initial basal acid secretion' after 5 days, while two patients who had been treated with omeprazole for a longer time (30-32 months) recovered only 38 and 40%, respectively, of their 'initial basal acid secretion' at the tenth day. Our results indicate that the omeprazole dosage to be used in the treatment of Zollinger-Ellison syndrome must be chosen principally on the basis of basal acid secretion determination. A low daily dose of omeprazole is able to control acid secretion in Zollinger-Ellison syndrome for a long period (10-30 months). The slow recovery of gastric secretory function demonstrates the prolonged inhibitory effects of omeprazole.

Quantitative ultrastructure of endocrine cells of oxyntic mucosa in Zollinger-Ellison syndrome. Correspondence with light microscopic findings

The endocrine cells of the oxyntic mucosa of five patients with longstanding Zollinger-Ellison syndrome were quantitatively investigated with electron microscopy and two light microscopic methods (Grimelius and immunostaining for chromogranin A). Ultrastructurally, the volume density of endocrine cells was 3.2% +/- 1.1% of the mucosal epithelial component, a 168% increase (P less than 0.001) over the value found in normal subjects. Of the six endocrine cell types of human oxyntic mucosa, only enterochromaffinlike cells increased in cell density (65% +/- 15% of the total endocrine cell mass), size, and number of cell profiles per unit area. The enterochromaffinlike cells also underwent morphological changes of secretory granules with a decrease in vacuolated forms, increase in elongated profiles, and appearance of granules with a punctate structure of the core. The latter variety of granules was previously observed only in carcinoid tumors of the oxyntic mucosa and is possibly related to the enterochromaffinlike cell hyperplasia-neoplasia sequence seen in hypergastrinemic patients. A positive relationship was found between endocrine cell densities evaluated ultrastructurally and with chromogranin A immunostaining. It is concluded that in Zollinger-Ellison syndrome, the trophic effects induced by longstanding hypergastrinemia are strictly selective for enterochromaffinlike cells and are associated with ultrastructural features typical for enterochromaffinlike cell tumors.

Medical treatment of antral gastrin cell hyperfunction: role of nonantisecretory therapy

Antral G cell hyperfunction (AGCH) is a rare condition, often associated with severe duodenal ulcer disease poorly responsive to medical therapy. Up to now, no studies have been designed to investigate a possible role of medical treatment in the management of this syndrome. In this study we treated 9 AGCH patients with duodenal ulcer, unhealed with the prolonging standard doses of H2 antagonists (300 mg/day ranitidine or 800 mg/day cimetidine), with a nonantacid therapy, tripotassium dicitrato bismuthate (TDB). 6 out of 9 patients showed a complete healing after 8 weeks of treatment. The healing was irrespective to eradication of Campylobacter pylori. After 9 weeks' suspension of H2 blockers basal gastrin levels decreased significantly by 31.5%, whereas peak meal-stimulated levels, although decreased in 6 out 9 patients, were not significantly affected by the withdrawal of the H2 antagonists. Nonantisecretory therapy seems to be an efficacious alternative in the management of AGCH patients.

Somatostatin infused during acute pancreatitis retains its biological activity

Somatostatin (SST) is used in the treatment of acute pancreatitis (AP) to inhibit pancreatic exocrine secretion, which represents one of the goals of medical treatment in this disease. Its therapeutic efficacy, however, is poor. One hypothesis, which has not yet been investigated, is that i.v. SST might be broken down by blood proteolytic enzymes. In order to evaluate the structural integrity and biological activity of infused SST, somatostatin-like immunoreactivity (SLI) and levels of pancreatic enzymes were monitored in the blood stream during the infusion of SST-14 (3,5 micrograms/kg/h for 48 h) in eight patients with severe acute pancreatitis. SLI was measured by both radioimmunoassay (RIA) and high-pressure liquid chromatography (HPLC). The results indicate that SLI levels increase promptly after the beginning of infusion, with a slower increase between 6 and 36 h, and a rapid increase again at 48 h. HPLC analysis shows a single peak of SLI with the same retention time as standard SST-14. Total amylase, lipase, and trypsinogen significantly decreased compared with pretreatment values (48, 63.1, and 77.4%, respectively) after 24 h of SST infusion, while a decrease in elastase 1 (62.6%) was observed later at 48 h. These results indicate that in severe AP, somatostatin recovered in plasma retains its biological activity: it inhibits pancreatic circulating enzymes, an action not influenced by breakdown of the peptide, as demonstrated by HPLC of the SLI measured in plasma.

Evidence that bombesin releases extragastric gastrin in man

Bombesin-induced gastrin release from extragastric sources has been investigated in two groups of patients without gastric antrum: 11 patients with total gastrectomy and 11 patients with subtotal (Billroth II) gastrectomy. A 30-min bombesin infusion (5 ng . kg-1 . min-1) caused a prompt significant gastrin increase (P less than 0.05) in both groups of patients. The gastrin response to bombesin was significantly (P less than 0.005) lower in patients without antral tissue than in the control group (n = 7). The individual peak gastrin responses, in totally (TG) and subtotally (SG) gastrectomized patients, were significantly over basal levels (TG: peak 100.3 +/- 12 vs. basal 62.8 +/- 9.1, P less than 0.005; SG: peak 96.9 +/- 9.4 vs. basal 72.4 +/- 6.8, P less than 0.001; pg/ml, mean +/- S.E.M.). These data indicate that bombesin acts not only on antral G cells, but on all gastrin cells in the gastrointestinal tract.