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Biomedical subjects

D M Goldenberg

Publications and source records attributed to D M Goldenberg.

At least 55 records · Page 3Linked to original sources
PubMed1999

Enhancement of tumor-to-nontumor localization ratios by hepatocyte-directed blood clearance of antibodies labeled with certain residualizing radiolabels.

UNLABELLED: To increase tumor-to-nontumor localization ratios of injected radiolabeled antibodies (Abs), several interrelated methods were used. METHODS: The model systems used were two human carcinoma xenografts grown in nude mice, targeted by antibodies RS11 (antiepithelial glycoprotein-2) or MN-14 (anticarcinoembryonic antigen). The Abs were conjugated with biotin and 111In-benzyl diethylenetriamine pentaacetic acid, and, at various times after injection, were cleared by intraperitoneal injection of galactosylated streptavidin, which delivers the complexes to hepatocytes. The radiolabel used was selected because it is retained within tumors after catabolism of the Ab by the tumor cell but is quite rapidly excreted from hepatocytes into bile. RESULTS: With blood clearance induced at 24 h, and dissection 5 h later, high tumor-to-nontumor ratios were attained. Depending on the model used, tumor-to-blood ratios were 16:1 to 31:1, and tumor-to-nontumor ratios for the kidney, lungs and bone were also high and greatly increased by the clearance regimen. Despite clearance into the liver, tumor-to-liver ratios remained >1, due to fairly rapid biliary excretion of the label. The absolute antibody uptake by the tumors was also high, because 24 h was allowed for the Ab to penetrate and bind to cells within the subcutaneous tumors. CONCLUSION: The method described produced high tumor-to-nontumor ratios at 1 d after injection and may be advantageous for tumor imaging with antibodies. Radiation dosimetry calculations indicate that there is only a slight advantage with this approach for radioimmunotherapy.

Animals↗
PubMed1999

Prediction of hematologic toxicity after radioimmunotherapy with (131)I-labeled anticarcinoembryonic antigen monoclonal antibodies.

UNLABELLED: This study was undertaken to determine the factors affecting myelotoxicity after radioimmunotherapy (RAIT) with 131I-labeled anticarcinoembryonic antigen (anti-CEA) monoclonal antibodies (MAbs). METHODS: Ninety-nine patients who received 131I-labeled MN-14 or NP-4 anti-CEA MAbs for the treatment of CEA-producing cancers were assessed for platelet and white blood cell (WBC) toxicity based on the common Radiation Therapy Oncology Group (RTOG) criteria. Univariate and multivariate regression analyses were used to identify the statistically significant factors affecting toxicity among the following variables: red marrow dose, baseline platelet and WBC counts, bone or marrow (or both) metastases, prior chemo- or radiotherapy, timing of prior chemo- or radiotherapy in relation to RAIT, type and number of prior chemotherapeutic regimens, age, sex, antibody form and cancer type. RESULTS: Red marrow dose, baseline platelet or WBC counts and multiple bone or marrow (or both) metastases were the only significant factors affecting hematologic toxicity according to both univariate and multivariate analyses, whereas chemotherapy, 3-6 mo before RAIT, was significant according to multivariate analysis. In this retrospective study, the multivariate regression equations using these four variables provided an exact fit for postRAIT platelet toxicity grade (PltGr) and WBC toxicity grade (WBCGr) in 40% and 46%, respectively, of the 99 patients included in the analysis. Moreover, severe (grade 3 or 4) PltGr and WBCGr could be classified accurately in all cases, whereas nonsevere (grade 0, 1, or 2) PltGr and WBCGr could be classified accurately in all but 6 of 13 cases of grade 2 toxicity, in which a severe toxicity grade was estimated using the regression equations. CONCLUSION: Red marrow dose, baseline blood counts, multiple bone or marrow (or both) metastases and recent chemotherapy are the most important factors related to hematologic toxicity after RAIT. This study provides a simple model for predicting myelotoxicity with reasonable accuracy in most patients. In addition, the identification of bone or marrow (or both) metastases and recent chemotherapy as significant factors for myelotoxicity may be important in the future design of clinical trials.

Age Factors↗
PubMed1999

Radiolabeling of an anti-carcinoembryonic antigen antibody Fab' fragment (CEA-Scan) with the positron-emitting radionuclide Tc-94m.

The goal of this work was to test whether an antibody-based agent approved for use as a single-photon-emitting imaging agent when radiolabeled with technetium-99m could be labeled comparably with a positron-emitting nuclide, technetium-94m. "Instant kits" containing lyophilized NP-4 antibody Fab' fragment of an anticarcinoembryonic antigen IgG (CEA-Scan) from the same manufactured lot were reconstituted with either Tc-99m or Tc-94m, as solutions of sodium pertechnetate in isotonic saline solution. Radioanalyses of the labeled Fab' fragments by size-exclusion high-performance chromatography and TLC were carried out. Equivalent results were obtained for radioimmunoconjugates when each was analyzed with both methods. Facile incorporation of Tc-94m into tumor-targeting Fab' antibody fragments will enable investigation of such agents for tumor-specific imaging using positron emission tomography.

Antibodies, Monoclonal↗
PubMed1999

Studies on the red marrow dosimetry in radioimmunotherapy: an experimental investigation of factors influencing the radiation-induced myelotoxicity in therapy with beta-, Auger/conversion electron-, or alpha-emitters.

Usually, the red marrow (RM) is the first dose-limiting organ in radioimmunotherapy. However, several studies have obtained only poor correlations between the marrow doses and the resulting toxicities. Furthermore, RM doses are mostly not determined directly but are derived from blood doses by assuming a ratio that is, over time for the respective conjugates, more or less constant between blood and marrow activities. The aim of this study was to determine, in a mouse model, this RM:blood activity ratio for various immunoconjugates, to investigate whether there may be differences between complete IgG and its fragments with various labels ((125/131)I versus (111)In, (88/90)Y, or 213Bi), and to analyze, in more detail, factors other than just total dose, such as dose rate or relative biological effectiveness factors, that may influence the resulting myelotoxicity. The maximum tolerated activities (MTAs) and doses (MTDs) of several murine, chimeric, and humanized immunoconjugates as complete IgG or fragments (F(ab)2 and Fab), labeled with beta(-)-emitters (such as 131I or 90Y), Auger electron-emitters (such as 125I or (111)In), or alpha-emitters (such as 213Bi) were determined in nude mice. Blood counts were monitored at weekly intervals; bone marrow transplantation was performed to support the assumption of the RM as dose-limiting. The radiation dosimetry was derived from biodistribution data of the various conjugates, accounting for cross-organ radiation; besides the major organs, the activities in the blood and bone marrow (and bone) were determined over time. Whereas no significant differences were found for the RM:blood ratios between various IgG subtypes, different radiolabels or various time points, differences were found between IgG and bi- or monovalent fragments: typically, the RM:blood ratios were approximately 0.4 for IgG, 0.8 for F(ab')2, and 1.0 for Fab'. Nevertheless, at the respective MTAs, the RM doses differed significantly between the three conjugates: e.g., with 131I-labeled conjugates, the maximum tolerated activities were 260 microCi for IgG, 1200 microCi for F(ab)2, and 3 mCi for Fab, corresponding to blood doses of 17, 9, and 4 Gy, respectively. However, initial dose rates were 10 times higher with Fab as compared to IgG, and still 3 times higher as compared to F(ab)2; interestingly, all three deliver approximately 4 Gy within the first 24 h. The MTDs of all three conjugates were increased by BMT by approximately 30%. Similar observations were made for 90Y-conjugates. Higher RM doses were tolerated with Auger-emitters than with conventional beta(-)-emitters, whereas the MTDs were similar between alpha- and beta(-)-emitters. In accordance to dose rates never exceeding those occurring at the single injection MTA, two subsequent injections of two doses of 80% of the single shot MTA of 131I- or 90Y-labeled Fab' and two doses of 100% of the single shot MTA of 213Bi-labeled Fab' were tolerated without increased lethality, if administered 24-48 h apart. In contrast, reinjection of bivalent conjugates was not possible within 6 weeks. These data suggest that the RM:blood activity ratios differ between IgG and fragments, although there is no anatomical or physiological explanation for this phenomenon at this point. In contrast to the current opinion, indication for a strong influence of the dose rate (or dose per unit time), not only total dose, on the resulting toxicity is provided, whereas the influence of high-linear energy transfer (alpha and Auger/conversion electrons) versus low-linear energy transfer (beta and gamma) type radiation seems to be much lower than expected from previous in vitro data. The lower myelotoxicity of Auger-emitters is probably due to the short path length of their low-energy electrons, which cannot reach the nuclear DNA if the antibody is not internalized into the stem cells of the RM.

Alpha Particles↗
PubMed1999

Epithelial mucin-1 (MUC1) expression and MA5 anti-MUC1 monoclonal antibody targeting in multiple myeloma.

Multiple myeloma (MM) is the second most common hematological cancer in the United States. It is typically incurable, even with myeloablative chemotherapy and stem-cell transplantation. The epithelial mucin-1 (MUC1) glycoprotein is expressed by normal and malignant epithelial cells but has also been shown to be expressed by MM cells. MUC1 is a useful antigenic target in solid tumors for clinical diagnostic and therapeutic monoclonal antibody (mAb)-based approaches. The MA5 mAb, as well as other anti-MUC1 mAbs reactive with the MUC1 variable number tandem repeat domain, exhibited moderate to strong reactivity with both MM cell lines and clinical samples. To explore the biochemical nature and potential of MUC1 as an antigenic target in MM, studies were performed to: (a) compare the mRNA and the MUC1 glycoprotein species between epithelial cancer and MM cell lines; and (b) develop and use a human MM tumor xenograft model system to study the biodistribution of the MA5 mAb. MA5 mAb was strongly reactive with six of eight human MM cell lines by flow cytometry. In seven of eight MM patient samples (bone marrow and/or peripheral blood) reactivity was found in 10-90% of the cells, whereas normal control (n = 5) and leukemia and lymphoma (n = 5) cells showed only 0-6% reactivity. 125I-labeled MA5 whole-cell binding studies showed quantitatively similar amounts of binding between strongly positive MM lines and high-MUC1-expressing breast carcinoma lines. mRNA expression was assessed by Northern blotting and reverse transcription-PCR. MM cell lines were positive by both methods, with strong similarity in the sizes of the mRNAs and cDNAs that were obtained. Finally, biodistribution experiments were carried out with 131I-labeled MA5 versus a nonbinding control 125I-labeled mAb in a s.c. MM xenograft model. Selective MM tumor uptake of the MA5 mAb was demonstrated, with a potential for delivering a tumor radiation absorbed dose of 8540 cGy/mCi of injected dose compared with 3099 cGy/mCi of tumor-absorbed dose delivered by nonspecific antibody.

Animals↗
PubMed1999

Targeting human cancer xenografts with monoclonal antibodies labeled using radioiodinated, diethylenetriaminepentaacetic acid-appended peptides.

A new nonmetabolizable peptide approach to the production of residualizing radioiodine was evaluated in nude mice bearing xenografts of human lung adenocarcinoma (Calu-3) and B-cell lymphoma (Ramos). Monoclonal antibodies (MAbs) RS7 (anti-epithelial glycoprotein-1) and LL2 (anti-CD22) were radioiodinated using the thiol-reactive diethylenetriaminepentaacetic acid-D-peptide adducts IMP-R1 and IMP-R2. 125I-IMP-R1- and 125I-IMP-R2-labeled MAbs were compared to the MAbs iodinated by the conventional chloramine-T approach, (111)In, and 131I-dilactitoltyramine (DLT). In vivo biodistribution studies demonstrated a significant improvement in the tumor accretion of radiolabel using the 125I-IMP-R1 labeled MAbs compared with the conventionally iodinated antibodies. For example, at day 7, the percentage of injected dose per gram of tissue in Calu-3 was 7.9 +/- 4.1% and 18.1 +/- 7.9% (P < 0.05) for the conventional 131I- and 125I-IMP-R1-RS7, respectively, and tumor:nontumor ratios were 2.6-4.5-fold higher with the 125I-IMP-R1-RS7. It is estimated that 131I-IMP-R1-RS7 would deliver a dose to tumor (at the estimated maximum tolerated dose) 3.9 times greater than conventional 131I-labeled RS7, 1.4 times greater than 90Y-labeled RS7, and 0.7 times that of 131I-DLT-labeled RS7. Tumor accretion of 125I-IMP-R2-RS7 was also improved compared with conventionally iodinated antibody. However, this label also caused a large increase in kidney accretion. Similar improvements in tumor accretion and tumor:nontumor ratios were observed when 125I-IMP-R1-LL2 was used in the Ramos model. IMP-R1 offers a practical and useful residualizing radioiodine label because labeling efficiency is at least 10 times greater than that of the residualizing label DLT, without MAb aggregation. Structural modifications can be envisioned for further improvements in radioiodine incorporation, specific activity, and tumor dosimetry, and efforts along these lines are under way.

Animals↗
PubMed1999

Humanization of Immu31, an alpha-fetoprotein-specific antibody.

Immu31 is a murine monoclonal antibody (Ab) specific for alpha-fetoprotein (AFP), a tumor-associated marker. The excellent tumor targeting ability of Immu31 has led to the development of a Immu31-based radioimmunodiagnostic agent, AFP-Scan, for hepatocellular carcinoma and other AFP-producing tumors. To enhance the capability of Immu31-based immunoconjugates being used in diagnostic and therapeutic procedures in humans, a humanized version of Immu31 (hImmu31) was constructed by grafting the complementarity determining regions (CDRs) of murine variable domains for the heavy (VH) and kappa (Vkappa) chain to the respective human VH and Vkappa framework regions (FRs). The cDNA encoding the VH and Vkappa of Immu31 was cloned by reverse transcription-PCR from hybridoma cells, and a chimeric Immu31 (cImmu31) composed of murine V and human C domains was constructed. Competitive ELISA assays showed identical AFP binding activity between the chimeric and murine Abs, confirming the authenticity of the cloned V genes. Based on sequence homology, the EU FR1, FR2, and FR3 and the NEWM FR4 were selected as the scaffold for grafting VH CDRs and REI FRs for Vkappa CDRs of Immu31. The amino acid residues in murine FRs that are considered to be in contact with the CDRs of the Ab were maintained in the humanized version. hImmu31, thus constructed and expressed, showed comparable immunoreactivity in a competitive binding ELISA assay to that of murine Immu31 and cImmu31. High-level production was achieved by expressing hImmu31 in a dhfr-based amplifiable system, and the productivity has exceeded 100 mg/liter in terminal cultures.

Amino Acid Sequence↗
PubMed1999

Generation and monitoring of cell lines producing humanized antibodies.

Antibody humanization has eliminated or reduced the human antimouse antibody response associated with the administration of murine antibodies. We have successfully humanized three different antibodies: (a) hMN-3 (granulocyte targeting); (b) hMu-9 (colorectal cancer targeting); and (c) hWI2 (anti-idiotype to the anti-carcinoembryonic antigen antibody MN-14). All humanized antibodies demonstrated immunoreactivities comparable to their parent counterparts. Previously, we reported the generation of high productivity cell lines for hMN-14 and hLL2 using the amplifiable vector pdHL2. Through amplification, selection, and cloning procedures, cell lines capable of large scale production were established, and further enhancement of production was achieved by a fed-perfusion bioreactor process. Using a similar and improved approach, we have enhanced the production of the above-mentioned humanized antibodies by gene amplification induced by a stepwise increase in the concentration of methotrexate in the culture media. A reliable IgG determination method is essential to monitor amplification, especially at the final cloning stage, for the selection of the subclones with the highest productivity. We found that measurement of humanized IgG concentration in culture media supplemented with more than 1 microM methotrexate by a standard ELISA assay could be unreliable and misleading. Whereas the determination of antibody by adsorption/elution on protein A from a 100-ml culture is accurate and reproducible, the method is time-consuming, tedious, and labor intensive. We have recently developed a Western blot assay that enables us to monitor the productivity of the cultures. The assay is simple and sensitive, and it makes simultaneous determinations of relative antibody production from individual clones at the 96-well stage feasible. With this method, amplification, cloning, and adaptation to serum-free conditions of multiple cell lines can be monitored in an efficient manner.

Animals↗
PubMed1999

The effects of domain deletion, glycosylation, and long IgG3 hinge on the biodistribution and serum stability properties of a humanized IgG1 immunoglobulin, hLL2, and its fragments.

Antibody (Ab) fragments are preferred agents for imaging applications because of their rapid clearance from the blood, thereby providing high tumor:blood ratios within a few hours. Several preclinical studies have also suggested that Ab fragments might be preferred for therapeutic applications over an intact IgG. The purpose of this project was to develop engineered Ab fragments using a humanized anti-carcinoembryonic antigen and anti-CD22 Ab as the parent. Three types of variants were prepared: a deltaCH2 (deletion mutant missing the CH2), a gamma3 F(ab')2 containing the human IgG3 hinge, and three glycosylated variants. The gamma3 F(ab')2 and glycosylated variants were developed because of the potential for site-specific linkage to the Ab in its divalent or monovalent fragment. The gamma3 F(ab')2 variant contains 10 cysteine residues that could be used for direct coupling using thiol chemistry, whereas the glycosylated variants have N-linked glycosylation sites engineered in the CH1 domain (two variants) as well as the VK domain (one variant). All of these variants were successfully prepared and shown to react with the target antigen. All Abs could be purified to a single peak by size-exclusion HPLC, but the deltaCH2 variant showed two distinct peaks, which were believed to be both the divalent and monovalent forms of this fragment. The two CH1 glycosylated variants showed differences in the extent of glycosylation. Modeling studies suggest that one variant would be better suited for site-specific coupling than the other because the carbohydrate chain is extended further away from the antigen-binding site. The Abs were radioiodinated to determine their pharmacokinetic behavior in mice. All of the humanized Ab divalent fragments cleared nearly 20 times faster from the blood than the murine parent F(ab')2 over a 24-h period. The glycosylated fragments showed some added stability compared to the other fragments over 4 h, but by 24 h, they had cleared to the same extent. Size-exclusion high-performance liquid chromatography of blood samples indicated that the humanized Ab fragments were quickly degraded in the blood. Thus, there is an inherent instability of the divalent fragments from these humanized IgG1 constructs that may affect their utility in imaging or therapy applications.

Animals↗
PubMed1999

Assessment of combined radioimmunotherapy and chemotherapy for treatment of medullary thyroid cancer.

We have shown previously significant antitumor effects using 90Y-MN-14 anti-CEA monoclonal antibody (MAb) for radioimmunotherapy (RAIT) of human medullary thyroid cancer (MTC) xenografts using the TT cell line. The purpose of this investigation was to determine the effect of combining chemotherapy and RAIT with 90Y-MN-14 in MTC. In particular, the toxicity and efficacy of various dose schedules of RAIT and doxorubicin were examined and compared with that at the maximum tolerated dose (MTD) of each single modality treatment. The MTD of RAIT of 105 microCi of 90Y-MN-14 was given alone and combined with 100 and 75% of the MTD of doxorubicin (60 mg/m2); and the MTD of doxorubicin was given alone and combined with 100 and 75% of the MTD of RAIT. In addition, 75% of each agent was also administered in combination. The MTD of RAIT was also evaluated in combination with 58 and 78% of the MTD of Taxol. Whereas 90Y-MN-14 (105 microCi) led to significant antitumor effects (P < 0.0001), doxorubicin at 60 mg/m2 or Taxol at 225 mg/m2 yielded only a slight tumor growth delay. The combinations of 100% of the MTD of RAIT and 75% of the MTD of doxorubicin and 100% of the MTD of doxorubicin and 75% of the MTD of RAIT were equitoxic to the MTD of RAIT alone and appear to result in improved efficacy compared with either RAIT or doxorubicin alone. For the 100% RAIT and 75% doxorubicin combination, the therapeutic efficacy was similar when doxorubicin was administered on the same day or 1 day after RAIT, but the treatment was less effective when doxorubicin was administered 2 days after RAIT (P < 0.03). Prolonged retardation of tumor progression was also observed in animals treated with the MTD of RAIT combined with 175 mg/m2 of Taxol, without increases in toxicity above that observed with RAIT alone. In conclusion, the combination of RAIT and chemotherapy appears to augment the antitumor effects of either treatment alone without a significant increase in toxicity. In addition, the timing of drug administration relative to RAIT in the combined therapy appears to be important.

Animals↗
PubMed1999

Radioimmunotherapy of small volume disease of colorectal cancer metastatic to the liver: preclinical evaluation in comparison to standard chemotherapy and initial results of a phase I clinical study.

At the time of surgery, occult metastases (micrometastases) are present in more than 50% of colorectal cancer patients, and the liver is the most frequent site of apparent metastatic disease. Frequently, adjuvant chemotherapy is unable to prevent tumor recurrence. Thus, novel therapeutic strategies are warranted. The aim of this study was to establish a model of human colon cancer metastatic to the liver of nude mice, to assess, in this setting, the therapeutic efficacy of radioimmunotherapy (RAIT) compared to standard chemotherapy and to evaluate, in a Phase I/II trial, the toxicity and therapeutic efficacy of RAIT in colorectal cancer patients with small volume disease metastatic to the liver. Multiple liver metastases of the human colon cancer cell line GW-39 were induced by intrasplenic injection of a 10% tumor cell suspension. Whereas controls were left untreated, therapy was initiated on day 10 or 20 after tumor inoculation with the 131I-labeled, low affinity anticarcinoembryonic antigen (anti-CEA) monoclonal antibody (MAb), F023C5 (Ka = 10(7) liters/mol), or the high-affinity anti-CEA MAb, MN-14 (Ka = 10(9) liters/mol), or chemotherapy (5-fluorouracil/leucovorin (folinic acid) versus irinotecan) at their respective maximum tolerated doses (MTDs). Twelve colorectal cancer patients with small volume disease metastatic to the liver (all lesions < or = 2.5 cm) were entered into a mCi/m2-based Phase I dose escalation study with 131I-labeled humanized version of MN-14, hMN-14. The patients were given single injections, starting at 50 mCi/m2 and escalating in 10-mCi/m2 increments. The MTD was defined as the dose level at which < or = 1 of 6 patients develop grade 4 myelotoxicity. In the mice, untreated controls died from rapidly progressing hepatic metastases at 6-8 weeks after tumor inoculation. The life span of mice treated with 5-fluorouracil/leucovorin was prolonged for only 1-3 weeks, whereas irinotecan led to a 5-8-week prolongation. In contrast, at their respective MTDs, the 131I-labeled low-affinity anti-CEA MAb, F023C5, led to a 20% permanent cure rate, and the high affinity MAb, MN-14, led to an 80% permanent cure rate, when therapy was initiated at 10 days after tumor inoculation. In the 20-day-old tumor stage, although it prolonged life, 131I-F023C5 was unable to achieve cures, whereas 131I-MN-14 was still successful in 20%. Histologically, no remaining viable tumor cells could be demonstrated in these animals surviving > 6 months. In patients, the MTD was reached at 60 mCi/m2 of hMN-14 (at 70 mCi/m2, two of three grade 4 myelotoxicities). Of 11 assessable patients, 2 had partial remissions (corresponding to an objective response rate of 18%), and 5 (45%) had minor/mixed responses or experienced stabilization of previously rapidly progressing disease. These data suggest that in small volume disease, RAIT may be superior to conventional chemotherapy. Antibodies of higher affinity seem to be clearly superior. The clinical response rates in patients with small volume disease are encouraging, being comparable to the response rates of conventional chemotherapeutic regimens but with fewer side effects. Ongoing studies will show whether treatment at the MTD will further improve therapeutic results.

Adult↗
PubMed1999

Pharmacokinetics, dosimetry, and initial therapeutic results with 131I- and (111)In-/90Y-labeled humanized LL2 anti-CD22 monoclonal antibody in patients with relapsed, refractory non-Hodgkin's lymphoma.

The pharmacokinetics, dosimetry, and immunogenicity of 131I- and (111)In-/90Y-humanized LL2 (hLL2) anti-CD22 monoclonal antibodies were determined in patients with recurrent non-Hodgkin's lymphoma. Fourteen patients received tracer doses of 131I-hLL2 followed 1 week later by therapeutic doses intended to deliver 50-100 cGy to the bone marrow. Another eight patients received (111)In-hLL2 followed by therapy with 90Y-hLL2 also delivering 50 or 100 cGy to the bone marrow. The blood T(1/2) (hours) for the tracer infusions of 131I-hLL2 was 44.2 +/- 10.9 (mean +/- SD) compared with 54.2 +/- 25.0 for the therapy infusions, whereas the values were 70.7 +/- 17.6 for (111)In-hLL2 and 65.8 +/- 15.0 for 90Y-hLL2. The estimated average radiation dose from 131I-hLL2 in tumors >3 cm was 2.4 +/- 1.9 cGy/mCi and was only 0.9-, 1.0-, 1.1-, and 1.0-fold that of the bone marrow, lung, liver, and kidney, respectively. In contrast, the estimated average radiation dose from 90Y-hLL2 in tumors >3 cm was 21.5 +/- 10.0 cGy/mCi and was 3.7-, 2.5-, 1.8-, and 2.5-fold that of the bone marrow, lung, liver, and kidney, respectively. No evidence of significant anti-hLL2 antibodies was seen in any of the patients. Myelosuppression was the only dose-limiting toxicity and was greater in patients who had prior high-dose chemotherapy. Objective tumor responses were seen in 2 of 13 and 2 of 7 patients given 131I-hLL2 or 90Y-hLL2, respectively. In conclusion, 90Y-hLL2 results in a more favorable tumor dosimetry compared with 131I-hLL2. This finding, combined with the initial anti-tumor effects observed, encourage further studies of this agent in therapeutic trials.

Adult↗
PubMed1999

Low- versus high-dose radioimmunotherapy with humanized anti-CD22 or chimeric anti-CD20 antibodies in a broad spectrum of B cell-associated malignancies.

Both CD22 and CD20 have been used successfully as target molecules for radioimmunotherapy (RAIT) of low-grade B cell non-Hodgkin's lymphoma. Because both CD20 and CD22 are highly expressed relatively early in the course of B cell maturation, and because its expression is maintained up to relatively mature stages, we studied the potential of the humanized anti-CD22 antibody, hLL2, as well as of the chimeric anti-CD20 (chCD20) antibody, rituximab (IDEC-C2B8), for low- or high-dose (myeloablative) RAIT of a broad range of B cell-associated hematological malignancies. A total of 10 patients with chemorefractory malignant neoplasms of B cell origin were studied with diagnostic (n = 5) and/or potentially therapeutic doses (n = 9) of hLL2 (n = 4; 0.5 mg/kg, 8-315 mCi of 131I) or chCD20 (n = 5; 2.5 mg/kg, 15-495 mCi of 131I). The diagnostic doses were given to establish the patients' eligibility for RAIT and to estimate the individual radiation dosimetry. One patient suffered of Waldenström's macroglobulinemia, eight patients had low- (n = 4), intermediate- (n = 2) or high- (n = 2) grade non-Hodgkin's lymphoma, and one patient had a chemorefractory acute lymphatic leukemia, after having failed five heterologous bone marrow or stem cell transplantations. Three of these 10 patients were scheduled for treatment with conventional (30-63 mCi, cumulated doses of up to 90 mCi of 131I) and 7 with potentially myeloablative (225-495 mCi of 131I) activities of 131I-labeled hLL2 or chCD20 (0.5 and 2.5 mg/kg, respectively); homologous (n = 6) or heterologous (n = 1) stem cell support was provided in these cases. Good tumor targeting was observed in all diagnostic as well as posttherapeutic scans of all patients. In myeloablative therapies, the therapeutic activities were calculated based on the diagnostic radiation dosimetry, aiming at lung and kidney doses < or = 20 Gy. Stem cells were reinfused when the whole-body activity retention fell below 20 mCi. In eight assessable patients, five had complete remissions, two experienced partial remissions (corresponding to an overall response rate of 87%), and one (low-dose) patient had progressive disease despite therapy. In the five assessable, actually stem-cell grafted patients, the complete response rate was 100%. Both CD20 and CD22 seem to be suitable target molecules for high-dose RAIT in a broad spectrum of hematological malignancies of B cell origin with a broad range of maturation stages (from acute lymphatic leukemia to Waldenström's macroglobulinemia). The better therapeutic outcome of patients undergoing high-dose, myeloablative RAIT favors this treatment concept over conventional, low-dose regimens.

Adolescent↗
PubMed1999

Importance of timing of radioimmunotherapy after granulocyte colony-stimulating factor administration for peripheral blood stem cell harvest.

Nine radioimmunotherapy (RAIT)-naive patients with medullary thyroid cancer received high doses of 131I-MN-14 F(ab)2 anti-carcinoembryonic antigen monoclonal antibody (232-486 mCi), five in combination with bone marrow harvest, without prior granulocyte colony stimulating factor (G-CSF) injections (group 1) and the other four using peripheral blood stem cell harvest (PBSCH) preceded by G-CSF administration of 10 microg/kg per day for 5 days for stem cell mobilization, 6-8 days before RAIT (group 2). The amounts of radioactivity (mCi) given in both groups were similar (312 +/- 93 versus 424 +/- 65; P = NS). The percent platelet loss at nadir, duration of grade 4 thrombocytopenia, and time to complete recovery (TTCR, measured from the day of treatment), were 83 +/- 17%, 2.5 +/- 0.7 days, and 45 +/- 8 days in group 1, respectively, compared with 88 +/- 6%, 3.0 +/- 2.6 days, and 50 +/- 24 days in group 2 (P = NS), respectively. In contrast, the percent WBC loss at nadir, duration of grade 4 leukopenia, and TTCR of WBCs were 72 +/- 12%, 0.0 +/- 0.0 day, and 42 +/- 12 days in group 1, respectively, compared with 93 +/- 3%, 8.0 +/- 3.6 days, and 263 +/- 136 days in group 2, respectively (P < 0.02, 0.03, and 0.05 for differences of percent loss, duration of nadir, and TTCR, respectively). The difference in WBC toxicity after RAIT with bone marrow harvest and PBSCH is thought to be due to the administration of G-CSF for stem cell mobilization within 1 week before RAIT, which may sensitize the "endogenous" granulocyte precursors to subsequent RAIT. Preclinical data of RAIT in mice showed that the time of G-CSF administration before RAIT is critical: increased WBC toxicity was seen in mice given RAIT 3 or 7 days after a 5-day course of G-CSF (81 and 57% WBC loss, respectively) compared with those given no G-CSF or G-CSF 10 or 14 days before RAIT (45-50%) WBC loss). In conclusion, our data indicate that the timing of RAIT after the administration of G-CSF for PBSCH may influence WBC toxicity and recovery after this treatment and may have important implications on the design of high-dose RAIT trials combined with PBSCH.

Adult↗
PubMed1998

Experimental studies on the role of antibody fragments in cancer radio-immunotherapy: Influence of radiation dose and dose rate on toxicity and anti-tumor efficacy.

Whereas bivalent fragments have been widely used for radio-immunotherapy, no systematic study has been published on the therapeutic performance of monovalent conjugates in vivo. The aim of our study was, therefore, to determine the therapeutic performance of (131)I-labeled Fab as compared to bivalent conjugates and to analyze factors that influence dose-limiting organ toxicity and anti-tumor efficacy. The maximum tolerated doses (MTDs) and dose-limiting organ toxicities of the (131)I-labeled anti-CEA antibody MN-14 [IgG, F(ab')2 and Fab] were determined in nude mice bearing s.c. human colon cancer xenografts. Mice were treated with or without bone marrow transplantation (BMT) or inhibition of the renal accretion of antibody fragments by D-lysine or combinations thereof. Toxicity and tumor growth were monitored. Radiation dosimetry was calculated from biodistribution data. With all 3 (131)I-labeled immunoconjugates [IgG, F(ab')2 and Fab], the red marrow was the only dose-limiting organ; MTDs were 260 microCi for IgG, 1,200 microCi for F(ab')2 and 3 mCi for Fab, corresponding to blood doses of 17 Gy, 9 Gy and 4 Gy, respectively. However, initial dose rates were 10 times higher with Fab as compared to IgG and 3 times higher as compared to F(ab')2. The MTD of all 3 immunoconjugates was increased by BMT by approximately 30%. In accordance with renal doses below 10 Gy, no signs of nephrotoxicity were observed. Despite lower absorbed tumor doses, at equitoxic dosing, Fab fragments were more effective at controlling tumor growth than the respective bivalent fragment or IgG, probably due to higher intratumoral dose rates. Our data indicate that the improved anti-tumor effectiveness of antibody fragments as compared to IgG and the higher myelotoxicity at comparably lower red marrow doses are most likely due to the higher initial dose rates observed with antibody fragments.

Animals↗
PubMed1998

Therapeutic efficacy and dose-limiting toxicity of Auger-electron vs. beta emitters in radioimmunotherapy with internalizing antibodies: evaluation of 125I- vs. 131I-labeled CO17-1A in a human colorectal cancer model.

Recent clinical results suggest that higher anti-tumor efficacy may be achieved with internalizing monoclonal antibodies (MAbs) at lower toxicity when labeled with Auger-electron, as compared to conventional beta-emitters. The aim of our study was to compare the toxicity and anti-tumor efficacy of the 125I-labeled internalizing MAb, CO17-1A, with its 131I-labeled form in a human colon cancer model in nude mice. Biodistribution studies were performed in nude mice bearing s.c. human colon cancer xenografts. For therapy, the mice were injected either with unlabeled 125I- or 131I-labeled C017-1A at equitoxic doses. Control groups were left untreated, were given a radiolabeled isotype-matched irrelevant antibody or a tumor-specific, but noninternalizing antibody. The maximum tolerated activities (MTD) of 131I-and 125I-CO17-1A without artificial support were 300 microCi and 3 mCi, respectively. Myelotoxicity was dose-limiting; bone marrow transplantation allowed for an increase of the MTD to 400 microCi of 131I-17-1A, whereas the MTD of 125I-17-1A with bone marrow support had not been reached at 5 mCi. Whereas no significant therapeutic effects were seen with unlabeled C017-1A, tumor growth was retarded with 131I-CO17-1A. With the 125I-label, however, therapeutic results were clearly superior. In contrast, no significant difference was observed in the therapeutic efficacy of the 131I- vs. 125I-labeled, noninternalizing antibodies. Our data indicate a superiority of Auger-electron emitters, such as 125I, as compared to therapy with conventional beta-emitters with internalizing antibodies. The lower toxicity of Auger emitters may be due to the short path length of their low-energy electrons, which can reach the nuclear DNA only if the antibody is internalized (as is the case in antigen-expressing tumor tissue, but not in the stem cells of the red marrow).

Animals↗
PubMed1998

Carbohydrates engineered at antibody constant domains can be used for site-specific conjugation of drugs and chelates.

To improve the efficiency of site-specific conjugation of chelates and drugs to antibodies, and to minimize the incidence of immunoreactivity perturbation to the resultant immunoconjugates, Asn-linked oligosaccharide moieties were designed and engineered into the constant domains of a humanized anti-CD22 monoclonal antibody, hLL2. From 10 potential glycosylation mutants, two CH1 domain glycosylation sites, HCN1 and HCN5, were identified that were positioned favorably for glycosylation. The carbohydrate (CHO) chains attached at these sites were differentially processed so that HCN5-CHOs were physically larger than HCN1-CHOs. Although both the CH1-appended CHOs, and the LL2 Vkappa-appended CHOs conjugated efficiently with small chelates, the HCN5-CHOs, due to the structural and positional superiority, appear to be a better conjugation site for large drug complexes, such as 18 kDa doxorubicin (DOX)-dextran.

Amino Acid Sequence↗