A Multi-Site Phase I Trial of Veliparib with Standard Radiation and Temozolomide in Patients with Newly Diagnosed Glioblastoma Multiforme (GBM).

Purpose: A multi-site Phase I trial was conducted to determine the safety, maximum tolerated dose, and pharmacokinetics (PK) of Veliparib, a Poly (ADP-ribose) polymerase [PARP] enzyme inhibitor, when administered with temozolomide (TMZ) alone and then with temozolomide and radiation (RT) in patients with newly diagnosed glioblastoma. Methods: Given the potential for myelosuppression when a PARP inhibitor is combined with chemotherapy, the first 6 patients accrued were given Veliparib 10 mg bid and TMZ 75 mg/m2/d daily for six weeks. If this was well tolerated, the same doses of Veliparib and TMZ would be tested along with standard radiation with plans to dose escalate the Veliparib in subsequent patient cohorts. Once a maximal tolerated dose was determined, a 78 patient phase II study was planned. Peripheral blood pharmacokinetics were assessed. Results: Twenty-four patients were enrolled. In the first 6 patients who received 6 weeks of TMZ with Veliparib only one dose limiting toxicity (DLT) occurred. The next 12 patients received 6 weeks of RT + TMZ + veliparib and 4/12 (33%) had dose limiting hematologic toxicities. As a result, Veliparib was reduced by 50% to 10 mg BID every other week, but again 3/3 patients had dose limiting hematologic toxicities. The trial was then terminated. The mean clearance (± SD) CL/F of Veliparib for the initial dose (27.0 ± 9.0 L/h, n = 16) and at steady-state for 10 mg BID (23.5 ± 10.4 L/h, n = 18) were similar. Accumulation for BID dosing was 56% (± 33%). Conclusions: Although Veliparib 10 mg BID administered with TMZ 75 mg/m2 for six weeks was well tolerated, when this regimen was combined with standard partial brain irradiation it was severely myelosuppressive even when the dose was reduced by 50%. This study again highlights the potential of localized cranial radiotherapy to significantly increase hematologic toxicity of marginally myelosuppressive systemic therapies.

Increased labeling of human melanoma cells in vitro using combinations of monoclonal antibodies recognizing separate cell surface antigenic determinants.

A panel of mouse anti-melanoma monoclonal antibodies (MoAb) were analyzed for reactivity with human melanoma cells singly and in combination. Five MoAb, ZME-018, 96.5, P94, 4.2, and 5.1, reactive with individual cell surface melanoma-associated antigens were tested with seven melanoma cell lines and seven fresh tumor biopsies. Cells were incubated with the MoAb, indirectly stained with fluorescein-conjugated goat anti-mouse immunoglobulin, and analyzed by flow cytometry. Percentage of labeled cells and relative fluorescence intensity (FI) with individual MoAb varied with different cell lines and biopsy samples. The most reactive MoAb, ZME-018, 96.5, and P94, labeled 29-93% of the cells from cell lines with relative FI of 2-59 units, thereby demonstrating phenotypic diversity of these cells. Similar results were obtained with cells derived from tumor biopsies, where 1-73% of cells were labeled and relative FI ranged from 0-27. These variations were reduced by using a "cocktail" of MoAb which recognized different melanoma-associated antigens. In cell lines both the percentage of labeled cells (range, 82-95%) and relative FI (range, 36-115) increased substantially (P less than 0.025 and P less than 0.005, respectively) when a "cocktail" prepared from all five MoAb rather than individual MoAb was used. A cocktail of MoAb increased the percentage of labeled tumor biopsy cells (range, 53-78; P less than 0.01) and relative FI (range, 11-69; P less than 0.025). The mean FI obtained by incubating cells with a cocktail of suboptimal concentrations of three MoAb (ZME-018, 96.5, P94) was 48 +/- 12 (SD), which was significantly increased compared to the mean FI seen with suboptimal concentrations of MoAb alone (ZME-018, 7 +/- 10; 96.5, 8 +/- 7; P94, 2 +/- 2; P less than 0.005). These findings were confirmed by radioimmunoassay using a combination of two MoAb, ZME-018 and 96.5. The data suggest that cocktails of MoAb were more effective than single MoAb alone for melanoma tumor cell labeling in vitro and might be more effective for tumor imaging and therapy.

Pharmacokinetics of 111In-labeled anti-p97 monoclonal antibody in patients with metastatic malignant melanoma.

Twenty-eight patients with metastatic malignant melanoma received anti-p97 murine monoclonal antibody (96.5) infused over 2 h at doses between 1 and 20 mg coupled to either 2.5 or 5.0 mCi of 111In by the bifunctional chelating agent diethyltriaminepentaacetic acid. Clearance of 111In from plasma closely fit an open, one-compartment mathematical model (r2 greater than 0.90). The overall half-life of 111In plasma was approximately 31 h and did not appear to be dependent on the total dose of antibody administered. The apparent volume of distribution of the 111In label approximated the total blood volume (7.8 +/- 0.7 liters) at the 1-mg dose and decreased to 3.0 +/- 0.14 liters at the 20-mg dose, suggesting saturation of antigenic or other extravascular binding sites at higher antibody doses. The clearance of the murine monoclonal antibody itself from plasma was measured by an enzyme-linked immunosorbent assay. The pharmacokinetics for the murine antibody in plasma also fit an open, one-compartment mathematical model. All pharmacokinetic parameters for unlabeled antibody closely paralleled those found for 111In-labeled antibody pharmacokinetics. This suggests that the 111In radiolabel remains complexed to the monoclonal antibody after in vivo administration. The cumulative urinary excretion of the 111In label over 48 h was between 12 and 23% of the total administered dose and is assumed to represent 111In-labeled chelate complex unattached to antibody. Analysis of the 111In label in spleen, liver, heart, and kidney showed that the concentration of label in liver tissue was reduced with increasing antibody doses and coincided with changes in the apparent volume of distribution. These studies show that murine monoclonal antibodies are cleared slowly from the circulation in humans and that early, rapid distribution of labeled antibody to the liver can be reduced by increasing the dose of unlabeled antibody. This may be particularly important in limiting hepatic toxicity when administering antibody coupled to drugs, radionuclides, or toxins.

Radioimmunoimaging in malignant melanoma with 111In-labeled monoclonal antibody 96.5.

A radiolabeled monoclonal antibody (96.5) reactive with an Mr 97,000 antigen found on over 80% of melanoma cell lines and tissue extracts was examined for its ability to detect malignant melanoma metastases in vivo. For imaging purposes, it was conjugated with diethyltriaminepentaacetic acid and subsequently labeled with 111In by chelation. Thirty-one patients with metastatic melanoma received single injections of monoclonal antibody 96.5 at concentrations ranging from 0.5 to 20 mg and at specific activities of 111In ranging from 0.125 to 4 mCi/mg. Total-body scans were performed at various time intervals following administration. No serious side effects were observed. Of a total of 100 previously documented metastatic sites, 50 imaged for a specificity of 50%. The number of sites imaged increased significantly as the amount of antibody administered increased relative to the average radiation dose. Considerable background uptake of isotope was observed in blood pool and other organs with gradual acquisition of label in tumor sites by 48 to 72 h. Hence, tumor imaging of melanoma using 111In-labeled monoclonal antibody 96.5 appeared feasible, especially at antibody doses above 2 mg.

Detection of metastatic adrenal carcinoma using 131I-6-beta-iodomethyl-19-norcholesterol total body scans.

Adrenal and total body scintigraphs with 131I-6-beta-iodomethyl-19-norcholesterol were obtained in 5 patients who had had prior resection of adrenal cortical carcinoma. The results were compared with roentgenographic findings and liver, bone, and total body gallium-67 citrate scintigraphs. Metastatic lesions were detected with radiolabeled cholesterol in 4 of 5 patients, including 3 liver metastases, 2 bone metastases, and 1 lung metastasis. These lesions were also demonstrated by one or more of the other diagnostic modalities. All initial findings were negative in a fifth patient, who developed brain metastases within two months. The 6-methyl-analog of iodocholesterol makes it possible to detect metastatic adrenocortical carcinoma with total body scans. Whether or not this agent is "tumor specific" and will be of significant clinical utility will have to be determined more fully in a larger series of patients.

Technetium-99m stannous citrate brain-tumor uptake in mice: concise communication.

The pharmacodynamics of technetium-99m stannous citrate were studies in Yale-Swiss mice bearing a sarcoma-like transplantable brain tumor, and the renal kinetics were determined in normal mice. Using a rating system based on tumor uptake and tumor-to-brain, tumor-to-blood, and tumor-to-skin ratios, the data obtained with this compound were compared with similar data obtained previously in the same model with Tc-99m Fe-(ascorbic acid), Tc-99m Fe-(ascorbic acid)-DTPA, Tc-99m Sn-DTPA, [99mTc] pertechnetate, and [99mTc] pertechnetate with perchlorate predose. Technetium-99m stannous citrate does not appear to achieve tumor localization by a mode different from these other Tc-99m-labeled compounds, nor does it show any potential advantage as a scanning agent in the tumor model.

Kinetics of 111In-bleomycin and 111 In-chlorides in mice.

Indium-111 as the chloride and chelated to bleomycin has been reported useful as a tumor-scanning agent. This report of the kinetics of these compounds compared in Yale-Swiss mice bearing a transplantable, in situ brain sarcoma. Indium-111-chloride, pH 1.5, gave a maximum tumor uptake of 18.5% dose per gram tumor, a maximum tumor-to-brain ratio of 17.0, and a maximum tumor-to-blood ratio of 4.4. Its renal blood clearance was a slow 0.0022 ml/min. Indium-111-bleomycin showed a maximum tumor uptake of 3.0% dose per gram tumor, a maximum tumor-to-brain ratio of 13.5, a maximum tumor-to-blood ratio of 6.8, and renal blood clearance of 0.254 ml/min. The labeling of bleomycin with 111In results in a tracer with localizing properties in this tumor model which are quite different from those obtained with 111In as chloride or that labeled to bleomycin would appear to have significant potential as agents for imaging tumors.

Brain tumor-scanning agents compared in an animal model.

Sixteen radiopharmaceuticals for brain tumor localization have been compared in a mouse brain tumor model. A rating system is presented for such intercomparison. The rusults indicate that 111-in-chloride injected at pH 1.5 has the most favorable biologic characterisTICS FOR BRAIN TUMOR IMAGING.

Radiation damage to mouse testis cells from [99mTc] pertechnetate.

The radiation dose and the biologic damage to mouse testis from intravenously administered [99mTc] pertechnetate were studied. The dose was measured for penetrating radiations from Tc-99m, using calibrated thermoluminescent dosimeters and calculations from the uptake of the nuclide in the testis, and was found to be 4.9 rada per mCi of Tc-99. The biologic damage was measured by the decrease in the number of sperm heads in the testis, counted both by hemacytometer and by Coulter counter. In preliminary experiments using external gamma radiation from Cs-137, the number of sperm heads reached a minimum 29 days after irradiation. Twenty-nine days after injection of 5.8 mCi of Tc-99m, which gives 28 rads to the testis, the number of sperm hads decreased to 70% of control. The biologic effect corresponds to that seen after 40 rads of gamma radiation from Cs-137. The damage to mouse testis cells from internally administered Tc-99m as measured in an in vivo system appears to be at least as significant as that from external gamma irradiation, if not more so.

Critical evaluation of serum thyroglobulin levels and I-131 scans in post-therapy patients with differentiated thyroid carcinoma: concise communication.

Serum thyroglobulin measurements by radioimmunoassay were performed in the follow-up of 68 patients with differentiated thyroid carcinoma undergoing I-131 total-body scans following surgery and/or I-131 therapy. Of 12 patients with distant metastases demonstrated by I-131 scan, thyroglobulin levels were elevated (greater than 60 ng/ml) in nine (75%); the remaining 25% either ranged between 20 and 60 ng/ml or were below 20 ng/ml in spite of having functional metastases. Of six patients with only regional lymph-node metastases demonstrated by I-131 scan, only one (16%) had an elevated thyroglobulin level, while two fell in the 20-60 ng/ml range and three were below 20 ng/ml. Of the remaining patients with no metastatic disease demonstrable by I-131 scan, three (6%) had elevated thyroglobulin levels. These patients were subsequently found to have metastatic disease by other criteria. These results suggest caution in the use of thyroglobulin levels as a replacement for I-131 scans in the follow-up of differentiated thyroid carcinoma. Based on our study, however, the two methods complement each other to achieve maximum sensitivity and reliability.

Clinical parameters related to optimal tumor localization of indium-111-labeled mouse antimelanoma monoclonal antibody ZME-018.

Radioimmunolocalization of an 111In-labeled mouse antimelanoma monoclonal antibody (MoAb), ZME-018, was examined in 21 patients with metastatic malignant melanoma. Each patient received a single. i.v. infusion of MoAb at concentrations ranging from 1 mg to 20 mg, coupled to 5 mCi 111In by the chelating agent DPTA. No toxicity was observed in any patient. Total-body and regions of interest scans performed at 4, 24, and 72 hr following MoAb administration revealed uptake in 63 out of 105 previously diagnosed metastases for an overall sensitivity of 60%. Uptake was consistently observed in liver/spleen, and less frequently in bowel, testes, axillae and bone. Sensitivity of detection increased significantly at doses of MoAb above 2.5 mg, with 74% of lesions imaging at 20 mg/5 mCi compared with 29% at 2.5 mg/5 mCi (p less than 0.005). A significant correlation was observed between tumor uptake of 111In-MoAb conjugate and increasing tumor size. Soft-tissue lesions such as skin and lymph node metastases were imaged to a greater extent (76%) than visceral metastases (19%). In five of six patients, biopsies obtained from 3 days to 14 days after MoAb administration showed antibody present on tumor cells as demonstrated by flow cytometry and/or radioimmunoassay. Human anti-murine immunoglobulin responses were observed in seven of 17 patients studied. Mean plasma clearance of ZME-018 was prolonged with a T1/2 of 24.7 hr and increased slightly with increasing MoAb dose. Urinary excretion of 111In averaged 12.4% of the injected dose over 48 hours. Radioimmunolocalization of melanoma with 111In-labeled ZME-018 appears feasible. The sensitivity of the technique was related to dose, tumor size, and disease site.

Experimental models for evaluation of radioactive tumor-localizing agents.

Although subject to limitations, there is a need for carefully controlled laboratory studies using animal tumor models in research on tumor-localizing agents. This paper reviews the literature relating to the more important transplantable tumor systems, spontaneous or induced, as to origin, host, site, and radioactive agent used. The historical background of animal tumor models is discussed, including such technical aspects as source of tumor, techniques of transplantation, transplantation sites, and maintenance of transplants. Also, considered are the use of animal tumor models as predictive systems, expression of experimental results of quantitative studies of tissue uptake and comparative radionuclide tumor and distributional studies, and suggestions for future studies, such as the need of more intensive study of existing tumor models for a better understanding of the relationship between animal and human tumors, the need for the development of new tumor model systems, and for standardization of experimental protocols and procedures. A total of 48 t,mor models (26 in mice, 11 in rats, 7 in hamsters, 2 in rabbits, and 2 in dogs) are presented in seven tables dividing the models into tumors of epithelial tissue, connective tissue, hematopoietic tissues, melanin-forming tissue, neural tissues, undetermined site of origin or undifferentiated histologic pattern, and miscellaneous background. The use of animal tumor models in cancer research, which utilizes radionuclides, permits the investigator to do many things not permissible with human beings, but the extrapolation of animal results to human beings must be approached with caution, Although malignant disease, whether in animals or man, must be individualized, certain trends in animal studies can be observed. It is the goal of the laboratory investigator to be able to indicate to the clinician those trends or phenomena that, when repeatedly observed in animal model systems, may be applicable to an understanding of malignant disease in man.

Radiation dose and biological effects to mouse testis from sodium 32P-phosphate.

Radiation dose to mouse testis was estimated to be about 1.65 rad per microCi of intravenously injected 32P. This high dose to the organ was due to the incorporation of this isotope into the macromolecules of the testis. Up to 30% of the total testis activity was in DNA molecules. Biologic effects on mouse testis from 32P were determined by testis weight loss and the decrease in the number of sperm heads in the testis. Number of sperm heads reached a minimum of 1.3% of control 36 days after injection of 3.5 microCi/g body weight of 32P. Significant decreases in sperm head counts were observed after as little as 0.2 microCi/g body weight of 32P.

Some aspects of the radiopharmaceutics of 99m-Tc-phytate.

This paper outlines the method of preparation of 99m-Tc-phytate and its use for scanning the reticuloendothelial system. The tissue distribution studies in mice and rats indicate that 99m-Tc-phytate is a safe and effective liver imaging agent. This was confirmed by preliminary studies in human subjects. The stability of the aqueous tin-phytate complex is remarkably good, and it could be successfully used for more than two months to prepare the labelled product.