Filgrastim treatment of acute myelogenous leukemia (M7) relapse after allogeneic peripheral stem cell transplantation resulting in both graft-versus-leukemia effect with cytogenetic remission and chronic graft-versus-host disease manifesting as polyserositis and subsequent bronchiolitis obliterans with organizing pneumonia.

Filgrastim (granulocyte colony-stimulating factor) has recently been reported to successfully treat patients with leukemic relapse after allogeneic peripheral stem cell transplantation (PSCT). However, the majority of the patients who responded also developed graft-versus-host disease (GVHD). Polyserositis as a manifestation of GVHD is a rare phenomenon. We report the first case of polyserositis following the use of filgrastim to treat a patient with acute myelogenous leukemia (M7), who had relapsed after an initially successful allogeneic PSCT. The polyserositis manifested with effusions and was initially controlled with high doses of steroids and pericardial stripping; however, after a quiescent period the patient eventually developed bronchiolitis obliterans with organizing pneumonia that required additional immunosuppressive therapy. We review the literature on GVHD-associated polyserositis and offer potential explanations for its pathogenesis.

Radioimmunotherapy with (111)In/(90)Y-2IT-BAD-m170 for metastatic prostate cancer.

PURPOSE: Over 31,000 Americans die of androgen-independent metastatic prostate cancer each year. New strategies that do not involve hormonal manipulation but instead recognize the biochemical and molecular characteristics of prostate cancer are needed. Radioimmunotherapy (RIT) uses a tumor-specific monoclonal antibody to deliver systemic, targeted radiation to cancer. The objectives of this Phase I study of (111)In-2IT-BAD-m170 (for imaging) and (90)Y-2IT-BAD-m170 (for therapy) were to determine the toxicity and maximum tolerated dose (MTD), the specificity for targeting metastatic prostate cancer, and the efficacy for palliation of pain. EXPERIMENTAL DESIGN: M170 is a mouse monoclonal antibody that targets adenocarcinomas. Patients with adequate renal and liver function, rising prostate-specific antigen, and androgen-independent metastatic prostate cancer were eligible. After estimation of dosimetry and pharmacokinetics with (111)In-2IT-BAD-m170, a single dose of (90)Y-2IT-BAD-m170 (0.185, 0.370, 0.555, or 0.740 GBq/m(2)) was administered to cohorts of three patients. Pain was assessed objectively by questionnaires before and for 8 weeks after RIT; weekly prostate-specific antigen levels were obtained for 2 months after RIT. RESULTS: The MTD of (90)Y-2IT-BAD-m170 was 0.740 GBq/m(2) for patients that had up to 10% of the axial skeleton involved with prostate cancer. Toxicity was almost exclusively confined to reversible myelosuppression. Metastatic prostate cancer was targeted by (111)In-2IT-BAD-m170 in all 17 patients. The mean radiation dose delivered to 39 bone and 18 nodal metastases by (90)Y-2IT-BAD-m170 was 10.5 Gy/GBq (range 2.8-25.1). Thirteen of 17 patients reported pain before (90)Y-2IT-BAD-m170; 7 of these 13 had a partial or complete resolution of pain that lasted an average of 4.3 weeks. CONCLUSIONS: This study determined the MTD of (111)In/(90)Y-2IT-BAD-m170 in patients with metastatic prostate cancer. The drugs were well tolerated, targeted metastases, and temporarily palliated pain.

Systemic administration of insulin-like growth factor (IGF)-binding protein-4 (IGFBP-4) increases bone formation parameters in mice by increasing IGF bioavailability via an IGFBP-4 protease-dependent mechanism.

Insulin-like growth factor (IGF)-binding protein-4 (IGFBP-4) is a potent inhibitor of IGF actions in vitro. However, we found that systemic administration of IGFBP-4 at pharmacological doses caused a significant increase in bone formation parameters in mice by a mechanism that may involve increased IGF bioavailability via proteolysis of IGFBP-4. To evaluate the hypothesis that proteolysis of IGFBP-4 is essential for the stimulatory effects of systemically administered IGFBP-4, we produced wild-type, protease-resistant, and IGFBP-4 proteolytic fragments and evaluated their effects using biochemical markers. Protease-resistant IGFBP-4 was more potent than wild-type IGFBP-4 in inhibiting IGF-I-induced mouse osteoblast cell proliferation in vitro and in inhibiting IGF-I-induced increase in alkaline phosphatase (ALP) activity in bone extract after local administration in vivo. Systemic administration of wild-type IGFBP-4, but not protease-resistant IGFBP-4, increased serum osteocalcin, serum ALP, and ALP in skeletal extracts in a dose-dependent manner, with a maximal effect of 40% (P < 0.05) at 1.25 nmol/mouse. Systemic administration of wild-type, but not protease-resistant, IGFBP-4 increased free IGF-I levels in serum in normal mice. IGF-I, but not wild-type IGFBP-4, increased bone formation parameters in IGF-I-deficient mice. This study demonstrates that systemic administration of IGFBP-4 increases bone formation parameters in mice by increasing IGF bioavailability in the circulation via an IGFBP-4 protease-dependent mechanism.

Prospective evaluation of cancer clinical trial accrual patterns: identifying potential barriers to enrollment.

PURPOSE: Well-conducted cancer clinical trials are essential for improving patient outcomes. Unfortunately, only 3% of new cancer patients participate in clinical trials. Barriers to patient accrual in cancer clinical trials must be identified and overcome to increase patient participation. MATERIALS AND METHODS: We prospectively tracked factors that potentially affected patient accrual into cancer clinical trials at the University of California Davis Cancer Center. Oncologists seeing new outpatients were asked to complete questionnaires regarding patient characteristics and the physician's decision-making on patient eligibility, protocol availability, and patient opinions on participation. Statistical analysis was performed to correlate these parameters with subsequent protocol accrual. RESULTS: There were 276 assessable patients. At the initial visits, physicians did not consider clinical trials in 38% (105/276) of patients principally because of a perception of protocol unavailability and poor performance status. Physicians considered 62% (171/276) of patients for participation in clinical trials. Of these, only 53% (91/171) had an appropriate protocol available for site and stage of disease. Seventy-six of 90 patients (84%) with available protocols met eligibility criteria for a particular study. Only 39 of 76 patients (51%) agreed to participate in cancer clinical trials, for an overall accrual rate of 14% (39/276). The remainder (37/76, 49%) declined trial participation despite meeting eligibility criteria. The most common reasons were a desire for other treatment (34%), distance from the cancer center (13%), patient refusal to disclose reason (11%), and insurance denial (8%). Patients with private insurance were less likely to enroll in clinical trials compared to those with government-funded insurance (OR, 0.34; P =.03; 95% CI, 0.13 to 0.9). CONCLUSION: Barriers to cancer clinical trial accrual can be prospectively identified and addressed in the development and conduct of future studies, which may potentially lead to more robust clinical trials enrollment. Investigation of patient perceptions regarding the clinical trials process and the role of third party-payers is warranted.

Systemic radiotherapy in metastatic breast cancer using 90Y-linked monoclonal MUC-1 antibodies.

Radioimmunotherapy (RIT) is a promising approach for treating metastatic breast cancer. Initial clinical trials using 131I radioimmunoconjugates, and more recent studies employing 90Y, have demonstrated objective, although transient, antitumor effects in heavily pretreated patients with minimal toxicity. Antibodies targeting unique epitopes of epithelial glycoprotein mucin (MUC-1) on breast cancer cell surfaces that have been studied in patients include BrE-3 (murine and humanized) and m170 (murine). Both antibodies react with at least 90% of breast cancers. In these and other RIT trials, myelosuppression has been the dose-limiting toxicity. However, this toxicity has been successfully circumvented with the use of autologous peripheral blood stem cell transplantation, and recent clinical trials have escalated 90Y doses up to 50 mCi/m(2). The therapeutic index indicates that using these agents with stem cell support should deliver 9000 to 18000 rads to metastatic tumors. Development of improved chelates that are readily metabolized in the liver may reduce doses to this organ, projected to be next in line as dose-limiting. Combination therapy will be required to produce durable benefits in metastatic breast cancer. Low dose taxanes are synergistic with RIT in preclinical studies and when administered in the optimal sequence could sensitize tumor cells to the continuous low dose radiation delivered by RIT, without increasing toxicity. The addition of systemically administered tumor targeting radiation therapy using RIT as part of combined modality therapy may enhance the rate of complete response and, in patients with minimal metastatic disease, could lead to curative therapy.

Postnatal and pubertal skeletal changes contribute predominantly to the differences in peak bone density between C3H/HeJ and C57BL/6J mice.

Previous studies have shown that 60-70% of variance in peak bone density is determined genetically. The higher the peak bone density, the less likely an individual is to eventually develop osteoporosis. Therefore, the amount of bone accrued during postnatal and pubertal growth is an important determining factor in the development of osteoporosis. We evaluated the contribution of skeletal changes before, during, and after puberty to the development of peak bone density in C3H/HeJ (C3H) and C57BL/6J (B6) mice. Volumetric bone density and geometric parameters at the middiaphysis of femora were measured by peripheral quantitative computed tomography (pQCT) from days 7 to 56. Additionally, biochemical markers of bone remodeling in serum and bone extracts were quantified. Both B6 and C3H mice showed similar body and femoral weights. B6 mice had greater middiaphyseal total bone area and thinner cortices than did C3H mice. Within strains, males had thicker cortices than did females. C3H mice accumulated more minerals throughout the study, with the most rapid accumulation occurring postnatally (days 7-23) and during pubertal maturation (days 23-31). C3H mice had higher volumetric bone density as early as day 7, compared with B6 mice. Higher serum insulin-like growth factor I (IGF-I) was present in C3H mice postnatally at day 7 and day 14. Until day 31, B6 male and female mice had significantly higher serum osteocalcin than C3H male and female mice, respectively. Alkaline phosphatase (ALP) was found to be significantly higher in the bone extract of C3H mice compared with B6 mice at day 14. These data are consistent with and support the hypothesis that the greater amount of bone accrued during postnatal and pubertal growth in C3H mice compared with B6 mice may be caused by increased cortical thickness, increased endosteal bone formation, and decreased endosteal bone resorption.

Evidence that IGF-binding protein-5 functions as a growth factor.

Recent studies support the concept that IGF-binding protein-5 (IGFBP-5) stimulates bone formation, at least in part, via IGF-independent mechanisms. To evaluate this hypothesis further, we evaluated in vitro and in vivo effects of IGFBP-5 on bone formation parameters using the IGF-I knockout (KO) mouse. Treatment of serum-free cultures of osteoblast clones derived from IGF-I KO mice with recombinant human IGFBP-5 increased both proliferation and alkaline phosphatase (ALP) activity in a dose-dependent manner, an effect comparable to that seen with IGF-I. IGF-II levels from media conditioned by osteoblasts derived from IGF-I KO mouse were below those detectable by RIA. To eliminate possible actions of IGF-II, if any was produced by osteoblasts derived from IGF-I knockout mice, the IGFBP-5 effect was studied in the presence of exogenously added IGFBP-4, a potent inhibitor of IGF-II actions in bone cells. Addition of IGFBP-4 blocked IGF-I- but not IGFBP-5-induced cell proliferation in osteoblasts derived from IGF-I knockout mice. Consistent with in vitro results, a single local injection of IGFBP-5 to the outer periosteum of the parietal bone of IGF-I KO mice increased ALP activity and osteocalcin levels of calvarial bone extracts. The magnitudes of IGFBP-5-induced increases in ALP and osteocalcin in parietal bone extracts of IGF-I KO mice were comparable to those seen in C3H mice. In contrast to IGFBP-5, local administration of IGFBP-4 had no significant effect on bone formation in C3H and IGF-I KO mice. These results provide the first direct evidence to our knowledge that IGFBP-5 functions as a growth factor that stimulates its actions in part via an IGF-independent mechanism.

Effects of recombinant insulin-like growth factor-binding protein-4 on bone formation parameters in mice.

Insulin-like growth factor (IGF)-binding protein-4 (IGFBP-4), one of the most abundant IGFBPs produced by bone cells, is a potent inhibitor of IGF actions in vitro. To evaluate the modulation of IGF actions on bone formation in vivo by IGFBP-4, we produced intact and fragment (50- to 100-fold reduced IGF affinity) forms of BP-4 and examined their local and systemic effects using biochemical markers. Local administration of IGF-I over the right parietal bone significantly increased bone extract alkaline phosphatase activity; this was completely blocked by an equimolar dose of intact IGFBP-4, but not IGFBP-4 fragment. A single sc administration of IGF-I (2 microg/g BW) significantly increased bone formation markers in both serum and skeletal extracts; surprisingly, so did intact IGFBP-4, but not fragment IGFBP-4. Subcutaneous administration of an equimolar dose of IGFBP-4 along with IGF-I did not significantly block the IGF-I effect. Administration of intact IGFBP-4 significantly increased the serum 50-kDa IGF pool and decreased the 150-kDa IGF pool without significantly changing total IGF-I. We postulate that the increase in the 50-kDa IGF pool might enhance IGFs bioavailability via a mechanism involving IGFBP-4-specific protease. This study demonstrates for the first time that a single local administration of IGFBP-4 inhibits IGF-I-induced increases in bone formation, whereas systemic administration of IGFBP-4 alone increases serum levels of bone formation markers.

Strategies for developing effective radioimmunotherapy for solid tumors.

Single-agent radioimmunotherapy (RIT) has proven efficacy as a treatment for hematological malignancies, particularly non-Hodgkin's lymphoma. Although promising, RIT has been less effective for solid tumors, in part because they are less radiosensitive. Bone marrow transplantation permits the administration of larger radiopharmaceutical doses, but the results of bone marrow transplantation-supported RIT for solid tumors have been marginal. The purpose of this publication is to provide an overview of promising RIT strategies for solid tumors. It is apparent that combination therapy is required, but optimization of the radiopharmaceutical should be the first step. Metallic radionuclides provide higher tumor radiation doses but not necessarily an improved therapeutic index, that is, the ratio of tumor:normal tissue radiation doses. Biodegradable peptide linkers between the chelated metal and the antibody improve the therapeutic index. Further improvements depend on identification of synergistic therapies which recognize that: (a) continuous, low-dose radionuclide therapy acts through apoptosis; and (b) apoptosis is often blocked because most tumors have ineffective p53 and increased Bcl-2. Taxanes are particularly attractive as synergistic agents for RIT because they induce cell cycle arrest in the radiosensitive G2-M phase and p53-independent apoptosis. Optimal sequence and timing for combined modality RIT are critical to achieve synergy. Data from preclinical and clinical studies will be reviewed to illustrate the potential of these strategies.

Dosimetry-based therapy in metastatic breast cancer patients using 90Y monoclonal antibody 170H.82 with autologous stem cell support and cyclosporin A.

Radioimmunoconjugates of 170H.82 (m170), a panadenocarcinoma monoclonal antibody, are effective for imaging primary and metastatic breast cancer. To evaluate m170 as a targeting agent for therapy, we developed (111)In- and 90Y-2-iminothiolane-2-[p-(bromoacetamido)benzyl]-1,4,7,10 tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid-m170 immunoconjugates with 99% purity by molecular sieving and immunoreactivity comparable to unmodified antibody. (111)In-m170 pharmacokinetic studies were performed prior to each therapy to determine the maximum dose of 90Y-m170 that could be administered without exceeding a limit of 800 rad to the liver, lungs, or kidneys or 250 rad to the whole body or bone marrow for each of three cycles of treatment. Peripheral blood stem cells (PBSCs) were harvested and cyclosporin A (5 mg/kg twice daily) was administered as strategies to ameliorate myelosuppression and prevent the development of HAMA, respectively. An (111)In imaging/pharmacokinetic study was performed, and the 90Y dose was calculated and administered. The liver was the 90Y dose-limiting organ. The mean and range of calculated doses (in rad/mCi) for the five patients evaluated were as follows: whole body, 2.3 (2.1-2.4); liver, 17.8 (12.7-22.2); lung, 6.4 (4.8-7.2); kidney, 6.9 (6.3-11.5); marrow, 3.6 (1.9-4.4); and tumors (n = 25), 71.5 (14.1-141.5). Of the three patients treated, with doses of 37, 54, and 57 mCi of 90Y, one had a partial response, one had measurable tumor reduction but less than a partial response, and one had stable disease for more than 1 month. PBSCs prevented prolonged myelosuppression. The therapeutic responses, coupled with an absence, thus far, of significant adverse sequelae, suggest that this dosimetry-based approach combined with PBSCs may lead to effective therapy when higher 90Y doses are reached.

Recombinant human insulin-like growth factor-binding protein-5 stimulates bone formation parameters in vitro and in vivo.

Insulin-like growth factor-binding protein-5 (rhIGFBP-5) is stored in bone and stimulates osteoblast cell proliferation in vitro. Bone formation is dependent on the number and activity of osteoblasts. We therefore evaluated the ability of recombinant human (rh) IGFBP-5 to increase osteoblast activity in vitro; both alkaline phosphatase (ALP) activity and osteocalcin levels showed a dose-dependent increase. In in vivo time-course studies, daily s.c. administration of 50 microg rhIGFBP-5/day/mouse significantly increased serum osteocalcin levels by day 7, and these levels were sustained through day 21. We further evaluated whether rhIGFBP-5 was as effective as IGF-I. Daily s.c. administration of rhIGFBP-5 (50 microg/day), IGF-I (13 microg/day), or IGF-I plus rhIGFBP-5 complex for 9 days increased serum osteocalcin levels by 58%, 65%, and 81% (P < 0.001 in all) and femoral bone extract ALP activity by 85% (P < 0.001), 29% (P < 0.05), and 13% (P = NS), respectively, and decreased carboxyl-terminal cross-linked telopeptide of type I collagen by 29% (P < 0.05), 20% (P = NS), and 12.5% (P = NS), respectively. One s.c. injection of rhIGFBP-5 (50 microg/mouse) increased serum osteocalcin and bone ALP activity by 21% (P < 0.05) and 27% (P < 0.02), respectively, after 5 days, but did not significantly increase serum IGF-I (1, 6, or 24 h/postinjection), suggesting that the effects of rhIGFBP-5 on bone are not mediated by increasing circulating IGF-I. Our data demonstrate that systemic administration of rhIGFBP-5, either alone or in combination with IGF-I, increases bone formation parameters in vivo.

Comparison of 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA)-peptide-ChL6, a novel immunoconjugate with catabolizable linker, to 2-iminothiolane-2-[p-(bromoacetamido)benzyl]-DOTA-ChL6 in breast cancer xenografts.

Radioimmunotherapy using 131I-ChL6 antibody has shown promise in patients with breast cancer. To enhance this potential, a novel ChL6 immunoconjugate that is catabolizable and tightly binds 90Y and (111)In was developed. The immunoconjugate, 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA)-peptide-ChL6, consists of the macrocyclic chelator DOTA linked to ChL6 by a peptide that is preferentially catabolized in the liver. The pharmacokinetic and dosimetric properties of the radioimmunoconjugates (RICs) (111)In- and 90Y-DOTA-peptide-ChL6 and (111)In- and 90Y-2-iminothiolane (2-IT)-2-[p-(bromoacetamido)benzyl]-DOTA-ChL6 were compared in athymic mice bearing HBT3477 human breast cancer xenografts. Each of the RICs was stable in vivo and concentrated well in the xenografts. Liver concentration, cumulative radioactivity (activity over time), and radiation dose of the DOTA-peptide-ChL6 RICs were one-third to one-half of those of the corresponding 2-IT-2-[p(bromoacetamido)benzyl]-DOTA-ChL6 RICs. Indium-111 RICs were imperfect tracers for corresponding 90Y RICs, although their pharmacokinetics and radiation dosimetries were similar. The results of this study were consistent with previously published in vitro data, which indicated that the peptide linker of DOTA-peptide-ChL6 was catabolized by cathepsin B. The cumulative activities and radiation doses to the liver of DOTA-peptide-ChL6 RICs were one-half of those of corresponding RICs with the 2-IT linker. Preliminary data from pilot studies in patients with breast cancer are in accord with these observations. These novel DOTA-peptide RICs seem to have excellent clinical potential for radioimmunotherapy associated with marrow transplantation, for which liver radiation is likely to be dose limiting for 90Y.

Synergistic therapy of breast cancer with Y-90-chimeric L6 and paclitaxel in the xenografted mouse model: development of a clinical protocol.

BACKGROUND: Paclitaxel (Taxol) has demonstrated synergistic enhancement of radioimmunotherapy (RIT) of breast cancer with Y-90 labeled antibody ChL6, in the xenografted mouse model. To determine the optimal sequence and timing of RIT and Taxol for a prospective clinical trial, efficacy and dosimetry in mice, and dosimetry in patients receiving RIT alone, were examined. MATERIALS AND METHODS: Mice bearing human breast cancer xenografts (HBT 3477) received i.v. Y-90-DOTA-peptide-ChL6 (260 microCi), and i.p. Taxol (300 or 600 micrograms) 72, 48, or 24 hours prior to RIT, or 6, 24, 48, or 72 hours after RIT. RESULTS: Taxol after RIT resulted in cure, CR, or PR of all mice (70/70 tumors) and demonstrated greater therapeutic enhancement (p = 0.001) than Taxol before RIT. Mice receiving 600 micrograms Taxol 48 hours after RIT achieved 88% cure (7/8 tumors). In mice, 57% and 42% of the radiation dose to tumor and marrow, respectively, was delivered from 48-336 hours after RIT; in patients receiving 90Y-DOTA-peptide-ChL6, the corresponding values were 56% and 22%. CONCLUSIONS: Taxol given approximately 48 hours after RIT provides coincident peak deposition of Taxol and Y-90 in tumor, and no Taxol in the marrow during the major radiation dose to marrow, resulting in therapeutic enhancement without observable additive toxicity. A clinical trial of low dose Taxol given after RIT to patients with metastatic breast cancer is planned.

Importance of temporal relationships in combined modality radioimmunotherapy of breast carcinoma.

BACKGROUND: The beneficial effects of radioimmunotherapy (RIT) may result from activation of molecular pathways that lead to programmed cell death (apoptosis). The influences of sequence and timing of 90Y-DOTA-peptide-ChL6 antibody (90Y-ChL6) and anti-epidermal growth factor receptor antibody (ch225) or paclitaxel (Taxol; Bristol-Myers Squibb, Princeton, NJ) on efficacy and toxicity were examined. METHODS: Groups of human breast carcinoma (HBT 3477) tumored mice received paclitaxel (300 or 600 microg) or ch225 (70, 150, or 350 microg) at various intervals before or after 90Y-ChL6. Mortality, hematologic toxicity, weight loss, and therapeutic efficacy were evaluated. RESULTS: Mice receiving paclitaxel within 24 hours of 90Y-ChL6 had a 100% response rate; 48% were cured when paclitaxel was given 6 or 24 hours after 90Y-ChL6. When 150 microg ch225 was given 24 hours before 90Y-ChL6, the response and cure rates surpassed those of 90Y-ChL6 alone. Timing of administration was critical, with mortality rates as high as 80% in some groups receiving 350 microg ch225 and 90Y-ChL6. CONCLUSIONS: In this aggressive human breast carcinoma model, combined 90Y-ChL6 and paclitaxel had a high therapeutic index with many cures. Sequence of administration was critical in order for ch225 or paclitaxel, when combined with 90Y-ChL6, to enhance the response rate.

Peripheral blood stem cell mobilization for hematopoietic support of radioimmunotherapy in patients with breast carcinoma.

BACKGROUND: In clinical trials of radiolabeled monoclonal antibodies targeting metastatic breast carcinoma, myelosuppression has been the initial dose-limiting toxicity. We previously have shown that mobilized peripheral blood stem cell transfusions ameliorate this toxicity of radioimmunotherapy (RIT). Because of the difficulty we experienced harvesting adequate numbers of precursor cells from some of these heavily pretreated patients, we have compared the mobilization results and clinical histories of the metastatic breast carcinoma patients referred for RIT with those of metastatic breast carcinoma patients referred for high dose chemotherapy (HDCT) with transplantation. METHODS: Mobilization of stem cells into the peripheral blood was accomplished using granulocyte-colony stimulating factor with or without chemotherapy. Granulocyte macrophage colony-forming assays (CFU-GM) and flow cytometric analysis for CD34 positive cells were used to evaluate the number of hematopoietic precursors mobilized and collected with each apheresis procedure. Clinical characteristics, including prior chemotherapy and external beam radiotherapy, tumor bulk, and performance status, were determined by chart review. RESULTS: Significantly fewer hematopoietic precursors (both CD34 positive cells and CFU-GM) were harvested per procedure from the six RIT patients compared with a group of six patients with metastatic breast carcinoma who had stem cells harvested prior to HDCT (P = 0.002). There was no significant difference between the groups with regard to age or prior radiotherapy. All the RIT patients had received more chemotherapy, had a less favorable performance status (1 vs. 0), and had measurable tumor, whereas all the HDCT patients had minimal residual disease. CONCLUSIONS: Patients enrolled in RIT studies had lower stem cell yields than metastatic breast carcinoma patients scheduled to receive HDCT with stem cell transplantation. Poor mobilization is unlikely to be due to the mobilizing regimen alone and may be related to the intensity of prior therapy and/or tumor bulk. Mobilizing adequate stem cells for multiple treatment cycles from patients on Phase I/II RIT trials may require new, more effective mobilizing regimens, but referral of patients earlier in their disease course, prior to chronic bone marrow damage and disease progression, is recommended strongly.

Radioimmunotherapy for breast cancer using indium-111/yttrium-90 BrE-3: results of a phase I clinical trial.

UNLABELLED: BrE-3 is a murine IgG1 monoclonal antibody that binds to 97% of human ductal breast cancer specimens. A previous study documented the ability of 111In-labeled 1,4-methyl-benzyl isothiocyanate diethylenetriamine pentaacetic acid (111In-MX-DTPA) BrE-3 to specifically target breast cancer tissue in patients, and the dosimetry derived from the pharmacokinetics suggested that a useful therapeutic index could be obtained with 90Y-MX-DTPA BrE-3. A Phase I maximum tolerated dose study was, therefore, initiated. METHODS: Six patients received 111In/90Y-MX-DTPA BrE-3, three of them receiving 6.25 and the other three receiving 9.25 mCi/m2 of 90Y. Pharmacokinetics, dosimetry, human anti-mouse antibody (HAMA), toxicity and clinical responses were evaluated. RESULTS: Three of six patients demonstrated a minor and transient, but objective tumor response, and none of the patients had significant toxicity. Tumor dosimetry ranged from 39 to 167 rad/mCi of 90Y (442-1887 rad/ dose). HAMA response occurred in five of six patients. CONCLUSION: Minimal toxicity, dosimetric calculations and clinical assessment indicate that a useful therapeutic index can be achieved with this therapy. Indium-111/yttrium-90-MX-DTPA BrE-3 can be safely administered to patients with metastatic breast cancer, and therapy doses yielded pharmacokinetics similar to those of tracer doses. Clinical responses, albeit transient, were achieved with single-dose therapy. Rapid onset of the HAMA response will hinder multicycle therapy, unless it is prevented with immunosuppressive drugs or the use of a "humanized" antibody. Further studies are needed to determine the optimal use of BrE-3 for radioimmunotherapy.

Radioimmunotherapy for advanced breast cancer using I-131-ChL6 antibody.

BACKGROUND: The biologically active, antiadenocarcinoma monoclonal antibody chimeric L6 (ChL6) was labeled with 131I and administered in cycles to patients with metastatic breast cancer who had failed standard therapy. The therapeutic potential, tumor targeting and maximum tolerated dose of 131I-ChL6 were studied. METHODS: Ten patients with L6 reactive breast cancer received an imaging dose of 131I-ChL6 followed 24 hours later by a therapy dose of 131I-ChL6 (20-70 mCi/m2). Patients received up to 4 monthly cycles unless they had significant myelosuppression, progression of disease, or a high human anti-mouse antibody titer. In vivo activation of effector cell function, complement levels and cytokine release were studied. RESULTS: All 10 patients had detectable cancer on the imaging study. In 7 patients with superficial cancer, the radiation dose was 120 to 3700 cGy/cycle; 5-30 times higher than the whole body dose. Therapy resulted in minimal acute or subacute toxicity. Dose limiting toxicities were neutropenia and thrombocytopenia. Six of 10 patients had clinically measurable tumor responses; 5 had responses that lasted more than one month (1.5-5 months). The MTD for 131I-ChL6, given in at least two monthly doses, was 60 mCi/m2. CONCLUSION: Objective clinical responses were seen in five of 10 patients treated with 131I-ChL6. The tumor response in heavily pretreated, advanced breast cancer may be related to the combined effects of targeted radiation and the biological activity of L6/ChL6.

Yttrium-90/indium-111-DOTA-peptide-chimeric L6: pharmacokinetics, dosimetry and initial results in patients with incurable breast cancer.

BACKGROUND: Radioimmunotherapy (RIT) using 131I-Chimeric L6 (ChL6) antibody has shown therapeutic promise for patients with breast cancer. To enhance this potential, a novel immunoconjugate was developed that targets adenocarcinomas like breast cancer and tightly binds yttrium-90 (90Y) for therapy and indium-111 (111In) for imaging. The radioimmunoconjugate consists of a macrocyclic chelator (DOTA) linked to ChL6 by a catabolizable peptide. 90Y-DOTA-peptide-ChL6 was designed to minimize the radiation dose to critical normal tissues, thereby improving the therapeutic index. MATERIALS AND METHODS: Three patients with incurable metastatic breast cancer received 90Y/111In-DOTA-peptide-ChL6 for 5 pharmacokinetics/dosimetry studies and one of these patients also received 2 therapy doses. Quantitative imaging of 111In and in vitro assay of 90Y and 111In in blood urine and bone marrow samples were obtained. RESULTS: 90Y/111In-DOTA-peptide-ChL6 was prepared at high purity and was stable in vivo. Assays of bone marrow revealed no evidence for escape of 90Y or 111In from the chelate. 111In imaging of tumors was excellent, providing a therapeutic index for tumor to marrow radiation as high as 229 to 1. 90Y and 111In provided comparable pharmacokinetics, as did tracer and therapeutic doses of radioimmunoconjugates. One patients that received 2 therapeutic doses of 90Y-DOTA-peptide-ChL6 showed regression of tumors and tumor markers. Toxicities were relatively minor and no anti-globulin response developed despite 5 immunoconjugate infusions. CONCLUSIONS: This first study in patients of radioimmunoconjugates with a catabolizable linker between the metal chelator and the antibody confirmed that these novel 90Y/111In-DOTA-peptide-ChL6 radioimmunoconjugates have significant potential. Tracer doses of 111In-DOTA-peptide-ChL6 for imaging predicted the behavior of therapeutic doses of 90Y-DOTA-peptide-ChL6. The latter radioimmunoconjugate induced regression of tumors and tumor markers without significant toxicity. When compared to earlier 131I-ChL6 dosimetry, 90Y-DOTA-peptide-ChL6 provided a therapeutic index several times better.

Radioimmunotherapy for breast cancer using escalating fractionated doses of 131I-labeled chimeric L6 antibody with peripheral blood progenitor cell transfusions.

Radioimmunotherapy (RAIT) using a humanized murine monoclonal antibody, chimeric L6 (ChL6), has produced objective tumor reduction in 50% of chemotherapy-refractory patients with metastatic breast cancer in our prior studies. Because myelosuppression limited dose escalation, we evaluated the ability of granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood progenitor cell (PBPC) transfusions to ameliorate this problem. 131I-labeled ChL6 was given at a starting dose of 150 mCi/m2 (2,5 times the maximum tolerated dose without PBPCs) for a planned three treatments. When blood radioactivity declined to less than 1 microCi/ml after treatment, PBPCs were transfused, and G-CSF was administered. Patient 1 had minimal myelosuppression, received two cycles of therapy, and then developed human antimonoclonal antibody (HAMA). Patient 2 had prolonged thrombocytopenia that resolved after additional PBPC transfusion. Progressive disease as well as HAMA prevented further treatment. Patient 3 received all three cycles of 150 mCi/m2 at 8-week intervals. Thrombocytopenia (< 25,000/microliter) occurred but was transient (0-7 days). Because HAMA developed in all prior patients who received G-CSF with ChL6 RAIT, including patients 1 and 2, who received PBPC, patient 3 was given cyclosporin for 14 days. She did not develop HAMA or significant toxicity following 3 cycles of RAIT. Cumulative radiation doses to her lungs and tumor were estimated at 3,100 and 11,200 cGy, respectively. For 9 months, she had a reduction in bone pain, a decline in serum tumor markers, and decreased tumor uptake of F-18-deoxyglucose on a positron emission scan. Her performance status improved, and she had no pulmonary toxicity. We conclude that: (a) PBPC transfusion can modify the myelotoxicity of RAIT and can permit repetitive dosing; (b) cyclosporin is a promising means to abrogate HAMA; and (c) fractionation of intensive-dose RAIT may increase the antitumor effect and reduce normal organ toxicity.