Genetic aspects of canine mixed leukocyte cultures.

Recent data stress the importance of matching donor and recipient of an organ graft for both the serologically defined (SD) and lymphocyte-defined (LD) determinants. To allow experimental evaluation of the effect of these SD and LD structures in a noninbred experimental animal, mixed leukocyte culture tests were performed between SD identical and nonidentical dogs to clarify the LD system in these animals. The results of these experiments can be summarized as follows: (a) In the dog there is a LD locus distinct from the known SD loci, which in all probability is localized outside the first (SD-1) series locus on the chromosome. (b) The crossing-over frequency between the SD and LD loci on the chromosome is low. (c) Studies in SD identical unrelated dogs and random unrelated dogs show an apparent high linkage disequilibrium between SD and LD loci. (d) The LD system in dogs is polymorphic.

Review of five consecutive studies of radiolabeled immunoglobulin therapy in Hodgkin's disease.

Recurrent Hodgkin's Disease (HD) provides unique opportunities to improve radiolabeled immunoglobulin therapy (RIT). Normal tissue toxicity after RIT is limited to bone marrow damage and is well documented and quantified in HD patients. Anti-antibody formation is rare in patients with HD, allowing for multiple RIT cycles. Overall, 134 patients with recurrent HD were treated on five different studies with i.v. antiferritin, labeled with 131I or with 111In for diagnostic purposes and 90Y for therapeutic purposes. Patients with recurrent, end-stage HD obtain a 60% response rate following 90Y-labeled antiferritin. One-half of the therapy responses are complete. Responses are more common in patients with longer disease histories (> 3 years) and smaller tumor volumes (< 30 cm3) and in patients receiving at least 0.4 mCi 90Y-labeled antiferritin/kg body weight. Complete responders survive significantly longer than partial responders (2 years versus 1 year). Partial responders survive longer than patients with progressive disease (1 year versus 4 months). HD in one-third of the patients recurs in new areas. A low protein dose (2-5 mg) and a moderate specific activity (10 mCi/mg) are recommended. Results obtained with 90Y-labeled antiferritin are significantly better than results with 131I-labeled antiferritin. Further translational research in vitro in the radio pharmacy and in vivo with experimental animals is ongoing to improve the therapeutic results of RIT in HD. Obviously, many permutations of RIT cannot be explored in HD patients for ethical, financial, or logistic reasons, and predictive preclinical research is required to achieve further progress. Currently, RIT is a low-toxicity, low-cost outpatient procedure for recurrent HD with a high response rate in a patient population with an unfavorable prognosis.

Preclinical analysis of intraperitoneal administration of 111In-labeled human tumor reactive monoclonal IgM AC6C3-2B12.

An IgM lambda human tumor cell-reactive monoclonal antibody was developed that reacts with cells of ovarian cancer, colorectal cancer, breast cancer, and certain other malignancies. The monoclonal antibody AC6C3-2B12, which was obtained from a recent recloning, was purified from tissue culture supernatants and analyzed by high-performance liquid chromatography and sodium dodecyl sulfate-PAGE. An animal model was developed in which human tumors grew either as solid peritoneal metastases or as s.c. nodules utilizing the human colorectal carcinoma cell line SW620. The biodistribution of 111In-labeled IgM conjugate was studied after i.v. or i.p. administration in nude mice bearing an s.c. xenograft or peritoneal tumor lumps of a human colorectal carcinoma (SW620). IgM administered i.v. cleared rapidly from blood and was deposited mainly in the liver [50% injected dose/g (ID)/g)], pancreas (20% ID/g), and kidney (10% ID/g) at 24 h. Tumor deposition was low (< or = 1.0% ID/g) in the s.c. tumor xenograft. In contrast, high tumor targeting (29% ID/g) was found in peritoneal tumor lumps after i.p. administration of 111In-labeled IgM. The biological half-life of IgM in the tumor was 100 h. Long peritoneal residence time (t 1/2 = 67 h) and low liver uptake (7% ID/g) were observed after i.p. administration. Blood activity was < 1% of the injected activity. Tumor:normal organ ratios were high (range, 2-290) from 2 to 144 h after i.p. administration. Whole body autoradiograms at 24 h after i.p. 111In-labeled IgM administration confirmed the biodistribution results. In normal beagle dogs, 75% of the i.p.-administered 111In-IgM decayed in the peritoneal cavity. The majority of the remaining radioactivity was taken up by mediastinal lymph nodes. Biological half-life in both locations was approximately 137 h. The i.p. administration of intact, specific radiolabeled IgM provides prolonged retention of radioactivity in tumor, low normal tissue uptake, a long peritoneal residence time, and very limited spillover of IgM into the circulation. This approach offers a promising new method for the diagnosis and treatment of certain patients with peritoneal carcinomatosis.

Separation of clonogenic tumor cells from small cell lung cancer bone marrow and small cell lung cancer cell lines.

One of the major obstacles to successful autologous bone marrow transplantation is tumor contamination of the marrow. We attempted to separate tumor cells from the marrow of patients with small cell lung cancer by layering bone marrow on a discontinuous albumin gradient and then assessing hematopoietic potential (CFUc) and clonogenic tumor cells (TCFUc) by standard techniques. In the six of seven patients whose bone marrow grew tumor colonies, 75 to 80% of CFUc could be found in Fraction 3 of the gradient; while 80 to 90% of TCFUc could be found in light-density Fraction 1 + 2. Furthermore, we observed tumor colony growth in Fraction 1 + 2 in some patients whose unfractionated bone marrow failed to grow tumor colonies. In separate experiments, we layered five cell lines established in patients with small cell lung cancer on the gradient and found that cells from four of the five lines also migrated to Fraction 1 + 2, and TCFUc from these lines were observed in Fractions 1 + 2 in three of four lines tested. We conclude that gradient fractionation may be one way of removing clonogenic tumor cells from the bone marrow of small cell lung cancer patients prior to autologous transplantation.

Survival of patients with resistant Hodgkin's disease after polyclonal yttrium 90-labeled antiferritin treatment.

PURPOSE: A follow-up study was initiated of patients with Hodgkin's disease who were treated with yttrium 90-labeled antiferritin. Prescription method, pharmacokinetics, acute and late side effects, and survival were evaluated. METHODS: Patients had measurable disease and failed > or = two multiagent chemotherapy regimens previously (N = 44). All patients received 5-mCi indium 111-labeled antiferritin 2 mg intravenously and were scanned repeatedly by gamma camera. In five patients, polyclonal antiferritin (rabbit, pig, or baboon) failed to target the tumor. Thirty-nine patients were injected intravenously with 10-, 20-, 30-, 40-, or 50-mCi yttrium 90-labeled antiferritin 2 to 5 mg. Patients received between one and five cycles. Some patients were supported with 5 x 10(7) autologous bone marrow cells per kilogram. RESULTS: Yttrium 90-labeled polyclonal antiferritin does not produce immunologic, pharmacologic, or microbiologic complications in vivo. Bone marrow toxicity is the only side effect observed. Overall response rate is 20 of 39, or 51%. Two patients had stable disease. A significant positive correlation is found between blood radioactivity level 1 hour after radioimmunoconjugate administration and subsequent response of Hodgkin's disease. A dosage in millicuries per kilogram provides a higher positive correlation with blood radioactivity levels 1 hour after administration than a dosage in millicuries per square meter of body-surface area or in total millicuries. Fifty percent of patients survive for > or = 6 months. CONCLUSION: The low-dose protein used (2 to 5 mg) indicates that the high response rate is due to radiation and not to immunologic effects of the antibody. High-activity administrations followed by bone marrow transplantation are not required for tumor response. The therapeutic ratio of radiolabeled antiferritin is higher than the therapeutic ratio observed in most phase I studies of chemotherapeutic agents. This analysis does not identify a superior mode of treatment for patients with end-stage Hodgkin's disease. However, in a heavily pretreated patient population, prolonged survival is observed after relatively inexpensive treatment. Preclinical research with yttrium 90-labeled antiferritin indicates that significant increases in tumor dose can be obtained in the future without an increase in normal tissue toxicity.

Etoposide, cyclophosphamide, total-body irradiation, and allogeneic bone marrow transplantation for hematologic malignancies.

PURPOSE: To determine the efficacy and toxicity of etoposide, cyclophosphamide, and fractionated total-body irradiation (TBI) as the conditioning regimen for allogeneic bone marrow transplantation (BMT) in patients with hematologic malignancies. PATIENTS AND METHODS: Seventy-nine patients underwent BMT from a human leukocyte antigen (HLA)-identical sibling using cyclosporine/methotrexate for graft-versus-host disease (GVHD) prophylaxis. Thirty-four patients had early leukemia (acute leukemia or lymphoblastic lymphoma in first remission, chronic myelogenous leukemia [CML], or refractory anemia [RA]), and 45 patients had more advanced disease. Patients received etoposide 1,500 mg/m2 on day -8, followed by cyclophosphamide 60 mg/kg/d on days -7 and -6, and 10.2 Gy of TBI administered in six fractions of 1.7 Gy given twice daily for 3 days from day -3 to -1. Donor bone marrow was harvested and infused on day 0. RESULTS: Patients with early leukemia had a disease-free survival rate of 53% +/- 9% and an overall survival rate of 57% +/- 10% at 3 years. Patients with advanced disease had a disease-free survival rate of 15% +/- 5% and overall survival rate of 17% +/- 5%. The actuarial relapse rate for the early-leukemia group is 33% +/- 9% versus 69% +/- 9% for patients with more advanced disease. Severe toxicity was most frequently manifested as pulmonary hemorrhage followed by multiorgan failure and death. The 100-day mortality rate for the early-leukemia group was 10% versus 50% for patients with more advanced disease. CONCLUSION: The combination of cyclophosphamide, etoposide, and TBI is a relatively safe and effective preparative regimen for patients with early hematologic malignancies. Controlled trials are needed to evaluate critically this combination versus other standard preparative regimens. Greater toxicity was observed in patients with advanced disease, and this program does not appear to offer any advantage over other regimens.

Allogeneic bone marrow transplantation for patients with high-risk acute lymphoblastic leukemia.

Seventy-four consecutive patients with high-risk acute lymphoblastic leukemia (ALL) were given cyclophosphamide (CY; 50 mg/kg on each of 4 days) plus total body irradiation (TBI; 300 rad on each of 4 days) followed by a human leukocyte antigen (HLA)-identical allogeneic bone marrow transplant (BMT). Eighteen patients in first complete remission (CR1), 36 in CR2, 16 in CR3, and four in CR4 were transplanted. Patients in CR1 were transplanted 1 to 8 months (median, 3 months) after attaining CR. All 18 patients in CR1 had one or more poor risk factors: age more than 18 (N = 17), initial leukocyte count greater than or equal to 20,000 (N = 11), Ph 1 chromosome (N = 2), delay in attaining CR more than 6 weeks (N = 8), or extramedullary disease (N = 1). Of those transplanted in CR2, 72% had relapsed on therapy. The 5-year event-free survival (EFS) rates for patients transplanted in CR1, CR2, and CR3 are 42%, 43%, and 25%, respectively, at median follow-up times of 57, 54, and 72 months, respectively. Children aged less than 18 years transplanted in CR2 have a 5-year EFS rate of 54%. All CR4 patients died early after transplant. The actuarial probability of relapse is 20%, 26%, and 48% for those transplanted in CR1, CR2, and CR3, respectively. Although there was substantial transplant-associated mortality, it decreased over the decade of the study (P = .01). This study indicates that BMT offers an attractive alternative to postremission chemotherapy in patients in CR1 with poor prognostic factors and in patients in second remission.

Phase I-II studies of yttrium-labeled antiferritin treatment for end-stage Hodgkin's disease, including Radiation Therapy Oncology Group 87-01.

Radiolabeled antiferritin immunoglobulin (Ig) preparations were tested in patients with advanced, end-stage Hodgkin's disease. Four patients received indium-111 (111In)-labeled monoclonal antiferritin (QCI). Targeting was not observed in tumor-bearing areas. Instead, scans showed rapid accumulation of QCI in normal liver. Forty-five patients were injected with 111In-labeled polyclonal antiferritin (rabbit, pig, or baboon). Forty (89%) patients showed tumor uptake, with dosimetric estimates ranging from 300 to 3,000 cGy in 1 week for the subsequently administered yttrium-90 (90Y)-labeled antiferritin. Yttrium-labeled antibody caused hematologic toxicity. Treatment-induced toxicity was not observed in any other organ system. Intravenous autologous bone marrow cells, 18 days after the yttrium infusion, accelerated hematopoietic recovery in eight patients receiving 30 mCi or 40 mCi. Hematopoietic recovery after a 20 mCi 90Y-labeled antiferritin infusion was not influenced by an autologous bone marrow transplant. Two patients receiving 20 mCi and one patient receiving 50 mCi remained aplastic after transplantation for unknown reasons. In 29 assessable patients, a 62% response rate was observed; nine of the 18 responses were complete. Responses ranging from 2 to 26 months were more commonly noted in patients with small tumors and long disease histories. Dosimetric calculations did not predict for responses. Recurrences frequently occurred in new areas instead of areas exhibiting bulky disease at the start of the treatment. Complete responses after 90Y antiferritin were significantly (P less than .02) more frequent than in a previous study with iodine-131 (131I) antiferritin. Further improvements are needed to make this new treatment modality curative.

Yttrium 90-labeled antiferritin followed by high-dose chemotherapy and autologous bone marrow transplantation for poor-prognosis Hodgkin's disease.

PURPOSE: This study was undertaken to examine the feasibility of combining radiolabeled antibody therapy with high-dose chemotherapy followed by autologous bone marrow transplantation in patients with poor-prognosis Hodgkin's disease. PATIENTS AND METHODS: Patients were entered onto this protocol if they had chemotherapy-resistant disease, bulky disease, or extensive prior therapy. Patients received yttrium-labeled antiferritin on day -13, -12, or -11, followed by high-dose cyclophosphamide, carmustine, and etoposide (CBV) on days -6 to -3, and then bone marrow infusion on day 0. RESULTS: Twelve patients received both radiolabeled antibody and high-dose chemotherapy followed by autologous transplantation. Two additional patients started the study, but were unable to complete all therapy. Four of 12 patients experienced early transplant-related mortality. Four patients are alive more than 2 years following transplantation and three are free from disease progression at 24+, 25+, and 28+ months following transplantation. The progression-free survival rate at 1 year is estimated to be 21%. Considering the poor prognostic characteristics of these patients, toxicity on this protocol was not necessarily greater than that observed with high-dose chemotherapy alone. CONCLUSION: This report demonstrates the feasibility of combining radiolabeled antibody therapy with high-dose chemotherapy and autologous bone marrow transplantation.

High-dose cytotoxic therapy and bone marrow transplantation for relapsed Hodgkin's disease.

Patients with Hodgkin's disease who have failed two or more chemotherapy regimens or who have relapsed after an initial chemotherapy-induced remission of less than 12 months are seldom cured with conventional salvage therapies. We studied the effect of high-dose cytoreductive therapy followed by bone marrow transplantation in 50 such patients with relapsed Hodgkin's disease. Twenty-one patients with histocompatibility locus antigen (HLA)-matched donors had allogeneic marrow transplants, one patient received marrow from an identical twin, and 28 patients without a matched donor received autologous grafts purged with 4-hydroperoxycyclophosphamide. Busulfan plus cyclophosphamide was the preparative regimen for the 25 patients who had received extensive prior irradiation, and the other 25 patients received cyclophosphamide plus total body irradiation. The overall actuarial probability of event-free survival at 3 years was 30%, with a median follow-up of 26 months. The event-free survival following transplantation was influenced by the number of chemotherapy failures and the patient's response to conventional salvage therapy prior to transplant. The 16 patients who were transplanted at first relapse, while still responsive to standard therapy, had a 64% actuarial probability of event-free survival at 3 years. Age, presence of extranodal disease, preparative regimen, and type of graft (autologous v allogeneic) were not significant prognostic factors. The majority of transplant-related deaths were from interstitial pneumonitis; inadequate pulmonary function, multiple prior chemotherapy regimens, and prior chest irradiation all appeared to increase the transplant-related mortality. These results suggest a role for marrow transplantation in a subset of patients with relapsed Hodgkin's disease who are unlikely to be otherwise cured but are still responsive to conventional-dose cytoreductive therapy.

Autologous and allogeneic bone marrow transplantation for chronic lymphocytic leukemia: preliminary results.

PURPOSE: This study was undertaken to evaluate the feasibility and therapeutic effect of high-dose chemoradiotherapy with autologous or allogeneic bone marrow transplantation (BMT) in patients with advanced chronic lymphocytic leukemia (CLL) who relapse after fludarabine treatment. PATIENTS AND METHODS: Twenty-two patients with advanced CLL received high-dose cyclophosphamide, total-body irradiation, and BMT. Eleven patients with relapsed CLL received autologous BMT with marrow collected during a prior fludarabine-induced remission; leukemia cells were depleted from the autologous marrow in seven patients using an anti-CD19 monoclonal antibody and immunomagnetic separation. Eleven patients received allogeneic or syngeneic BMT, seven of whom had refractory Rai stage III or IV disease. RESULTS: Six autologous transplant recipients achieved a complete remission (CR), four a nodular CR (nCR), and one a partial remission (PR). Two recurred with CLL, and three developed Richter's transformation. Two patients had recurrence of immune cytopenias while in morphologic remission; one of these patients died of cytomegalovirus pneumonia. Six of 11 patients survive in remission 2 to 29 months following BMT. Of the 11 patients who received allogeneic or syngeneic BMT, seven achieved a CR, two a nCR, and one a PR; 10 survive 2 to 36 months following BMT. CONCLUSION: These data indicate that high-dose chemotherapy with allogeneic BMT is effective at producing CRs in patients with CLL. Autologous transplantation in CLL is feasible and is capable of producing remissions in patients with advanced CLL. Further studies are warranted to assess the role of BMT in the treatment of CLL.

Pharmacokinetics of radiolabeled polyclonal antiferritin in patients with Hodgkin's disease.

The objective was to identify pharmacokinetic parameters predictive for tumor response and normal tissue side effects after i.v. administered radiolabeled rabbit antihuman ferritin IgG. Twenty-eight patients with recurrent Hodgkin's disease received 2 mg of rabbit antihuman ferritin i.v., labeled with 4-7 mCi of In-111 followed by two doses of 0.25, one dose of 0.3, or one dose of 0.4 mCi of Y-90-labeled antiferritin per kg of body weight 1 week later. Radioactivity and HPLC measurements of blood and urine samples and liver and tumor volumes identified on sequential whole-body scans provided the data for a pharmacokinetic analysis covering the first 6 days after the administration of the radioimmunoconjugate. Side effects and tumor response were recorded. Temporary hematological toxicity was noted in all patients. Sixteen patients showed a tumor response. The Y-90 blood level at 1 h after administration correlated with the severity of subsequent hematological toxicity. The rapid blood elimination half-life of radioactivity was 4.4 h. Less than 5% of the administered radioactivity was eliminated in the first 24 h urine. The slow blood elimination half-life was 44 and 37 h for In-111 and Y-90, respectively. One of 12 retreated patients produced anti-rabbit IgG antibodies. The volume of distribution was larger for Y-90 than for In-111-labeled antiferritin (160 versus 110% of estimated blood volume). Accidentally extravasated rabbit IgG was rapidly catabolized in perivascular tissues with an effective half-life of less than 35 h. Slower catabolism was noted for rabbit IgG in blood (t(1/2) = 40 h), liver (t(1/2) = 62 h) or tumor (t(1/2) = 40-80 h). Twelve of 13 patients with an effective tumor half-life > 57 h showed a tumor response. I.v. administered polyclonal rabbit antihuman ferritin, labeled with In-111 or Y-90 is stable in vivo and targets Hodgkin's disease. Intravascular Y-90 causes a vascular leak and a larger volume of distribution for antiferritin. Elevated Y-90 blood levels at 1 h and a tumor half-life of >57 h predict for hematological toxicity and tumor response, respectively.

Fractionated radiolabeled antiferritin therapy for patients with recurrent Hodgkin's disease.

The objective of this study was to determine the therapeutic ratio of fractionated radiolabeled immunoglobulin therapy (RIT) for patients with recurrent Hodgkin's disease. Ninety patients with recurrent Hodgkin's disease received 2 mg of yttrium-90-labeled polyclonal rabbit antihuman ferritin IgG i.v. Fifty-seven patients received a single (unfractionated) administration per treatment cycle; 11 of them were treated with 0.3 mCi/kg body weight, 39 were treated with 0.4 mCi/kg body weight, and 7 received 0.5 mCi/kg body weight per treatment cycle. Thirty-three patients had their radiolabeled immunoglobulin administration separated (fractionated) in 2 x 0.25 mCi/kg body weight (total activity, 0.5 mCi/kg). The interval between fractions was 1 week. Radioimmunoconjugates did not cause serious acute side effects. In vivo radioimmunoconjugates were stable. Human antirabbit IgG antibodies were found in 2 of 50 retreated patients (<5%). Hematological toxicity was the only side effect noted in all patients, and it was usually temporary. Response rates (RRs) were 20%, 61%, and 86% after 0.3, 0.4, or 0.5 mCi/kg unfractionated yttrium-90-labeled antiferritin. The RR for patients treated with fractionated RIT was 42%. In the fractionated RIT group, complete responses were decreased, and progressive disease increased (P < 0.05). Complete responses had a medium duration of 6 months. Median survival times were 390 days for 1 x 0.4 mCi/kg and 300 days for the 2 x 0.25 mCi/kg patient group. Fractionation did not provide the expected decrease in hematological toxicity or the expected increase in tumor RRs.

Optimal prescription method for cancer chemotherapy.

A reexamination of the guidelines for prescriptions for cancer chemotherapy suggests that the use of body surface area (BSA) offers a simplification that may be open to some question. The same drug dose per BSA will give approximately the same toxicity in different age groups and species. This simplification appears to be fortuitous, however, as BSA does not correlate with the dose-limiting target cells, i.e., the hemopoietic stem cell. In patients with an unmodified hemopoietic system, body weight correlates significantly with hemopoietic stem cell concentration. It can be shown that changing the prescription unit from BSA to kilogram (kg) could lead to safer doses in children and neonates. In general, because of low therapeutic index, the expression of cancer chemotherapy drugs per dose-limiting normal tissue target cells could lead to safer and more effective cancer chemotherapy. New assays for prospective in vitro enumeration of dose-limiting target cells need to be developed. The indiscriminate use of BSA as a drug dose unit is discouraged.

Gastrointestinal decontamination of dogs treated with total body irradiation and bone marrow transplantation.

Procedures for total and selective gastrointestinal decontamination of dogs are described. The selective procedure removed only Gram negative aerobic bacteria, yeast and fungi. Dogs receiving total decontamination were less susceptible to the GI syndrome following total body irradiation (TBI) than dogs receiving conventional care. After TBI and allogeneic bone marrow transplantation, serum albumin levels decreased in conventional animals, but remained normal in totally or selectively decontaminated animals. Exogenous infections occurred frequently in both irradiated, and totally decontaminated animals, but were absent in selectively decontaminated animals. Endogenous infections after total body irradiation were prevented only by total decontamination. Endogenous infections occurred in selectively decontaminated animals, but with milder clinical symptoms than in conventional animals. Appearance of donor type leukocytes and serum gamma globulin was slower in decontaminated animals than in conventionally treated controls. Acute graft versus host disease caused by a limited number of lymphocytes of a DLA identical littermate donor were prevented by selective gastrointestinal decontamination. Complications due to late immune reconstitution obscured the effect of decontamination on delayed graft versus host disease.

Autologous bone marrow transplantation in breast cancer: separation of clonogenic tumor cell colonies by gradient fractionation.

A major obstacle to successful autologous bone marrow transplantation in breast cancer is infiltration of the marrow by malignant cells. We layered bone marrow samples from seven breast cancer patients on a discontinuous bovine albumin gradient, then assessed hematopoietic potential (colony-forming units-culture [CFUc]) and clonogenic tumor cells (TCFUc) by standard techniques. We found that 78% of CFUc concentrated in fraction 3 of the gradient, which contained 10% of the total nucleated cell population. TCFUc were distributed across the gradient with 14% of colonies identified in this marrow fraction. We applied these techniques to two patients with metastatic breast cancer who were treated with high-dose mitomycin-C, doxorubicin, and cyclophosphamide before receiving 1.9 x 10(9) and 1.2 x 10(9) total cells, respectively, from CFUc-rich fraction 3. We observed tumor colony growth in three patients only in separated marrow fractions, suggesting that colony growth may be a function of the cell composition after fractionation or that growth factors may be separable. Ninety percent of clonogenic breast cancer cells can be separated from hematopoietic cells by discontinuous density gradient fractionation, a technique that is applicable to the large volumes necessary in bone marrow transplantation and that may be an important initial step in marrow purging for autologous transplantation.

Hematologic side effects of radiolabeled immunoglobulin therapy.

Radiolabeled immunoglobulin therapy (RIT) is a new cancer treatment that is more selective than its predecessors. Its dose-limiting normal tissue side effect is bone marrow toxicity, and hematopoietic stem cell damage appears to be its most significant mechanism. Platelet consumption in irradiated normal liver tissues and apoptosis of circulating peripheral blood lymphocytes are other, less important, hematologic side effects. 131I and 90Y are the radioisotopes most commonly used for RIT; in addition, animal toxicology and initial clinical studies of chelate immunoglobulins radiolabeled with 111In (for diagnosis) or 90Y (for therapy) are reviewed. The bone-seeking properties of free 90Y are not considered to be a major component of the hematologic damage caused by yttrium-labeled immunoglobulins. The microenvironment of the bone marrow system is not significantly damaged by current RIT protocols. Moreover, granulocyte colony-stimulating factor (G-CSF) can open the blood-marrow barrier. Bone marrow toxicity after RIT can be corrected by bone marrow transplantation, growth factors, blood products, or fractionation of RIT. Selection of the appropriate corrective regimen depends on the severity of the bone marrow damage and will further enhance the therapeutic ratio of RIT.

Estimation of hemopoietic potential by CFU-c and bone marrow scan in cancer patients.

The concentration of granulocyte-macrophage colonies in culture (CFU-c) in bone marrow cells was estimated, and bone marrow radionuclide scans were performed in a group of 15 cancer patients prior to bone marrow harvest for autologous transplantation. Preharvest CFU-c counts on iliac-crest bone marrow aspirates correlated very well with CFU-c counts from fresh and frozen-thawed bone marrows. Technetium-99m-sulfur colloid radionuclide scans showed that the distribution of total-body bone marrow and increased peripheral radionuclide uptake correlated with higher preharvest and harvest CFU-c counts. Bone marrow scan results were available in 1 h, whereas CFU-c counts took 14 days to obtain. Bone marrow scans may facilitate the clinical estimation of hemopoietic activity in patients under consideration for autologous bone marrow transplantation.

Radiobiological speculations on therapeutic total body irradiation.

Unexpected total body irradiation (TBI) of human beings, involved in nuclear warfare or in accidents in nuclear reactors can be lethal. In the 1950s, bone marrow transplantation was discovered as a potentially life saving procedure after TBI in the dose range of 5.0 to 12.0 Gy. Since that time, deliberate or "therapeutic" TBI has been used to condition patients with a lethal bone marrow disorder for bone marrow replacement. The therapeutic ratio of TBI followed by bone marrow transplantation is small. Many potentially lethal complications can occur, such as acute TBI side effects, late TBI side effects or immunological complications of bone marrow transplantation such as graft versus host disease or graft rejection. The benefits of TBI and bone marrow transplantation are that they offer a chance for cure of previously lethal bone marrow disorders. The optimal parameters for TBI remain to be defined. The review discusses the current clinical and experimental animal data, as they relate to the future definition of less toxic TBI procedures with a better therapeutic ratio. Different TBI procedures are required for patients with malignant vs. non-malignant disorders or for patients with histoincompatible vs. histocompatible bone marrow donors.

Interstitial pneumonitis after allogeneic bone marrow transplantation. Nine-year experience at a single institution.

Of 386 patients with allogeneic bone marrow transplants (BMT) treated during a 9-year interval, 166 developed interstitial pneumonitis (IP). Idiopathic and cytomegalovirus (CMV) IP constituted 90% of the 113 cases in which tissue was examined. Risk factors for IP overall were acute graft-versus-host disease (AGVHD), remote transplant date, the diagnosis of leukemia, and GVHD prophylaxis with agents other than cyclosporine. Risk factors for CMV IP were pre-transplant CMV seropositivity, CMV excretion, age greater than 10 years, AGVHD, GVHD prophylaxis with agents other than cyclosporine, and a remote transplant date. Patients transplanted for aplastic anemia were at lower risk for idiopathic IP than those transplanted for leukemia. The incidence of IP in patients given busulfan plus cyclophosphamide was equivalent to that in patients receiving cyclophosphamide plus total body irradiation. The incidence of idiopathic IP remained constant over this 9-year period while CMV IP declined significantly.