Autologous stem-cell transplantation after second-line brentuximab vedotin in relapsed or refractory Hodgkin lymphoma.

Background: We previously demonstrated that brentuximab vedotin (BV) used as second-line therapy in patients with Hodgkin lymphoma is a tolerable and effective bridge to autologous hematopoietic cell transplantation (AHCT). Here, we report the post-AHCT outcomes of patients treated with second-line standard/fixed-dose BV and an additional cohort of patients where positron-emission tomography adapted dose-escalation of second-line BV was utilized. Patients and methods: Patients on the dose-escalation cohort received 1.8 mg/kg of BV intravenously every 3 weeks for two cycles. Patients in complete remission (CR) after two cycles received two additional cycles of BV at 1.8 mg/kg, while patients with stable disease or partial response were escalated to 2.4 mg/kg for two cycles. All patients, regardless of treatment cohort, proceeded directly to AHCT or received additional pre-AHCT therapy at the discretion of the treating physician based on remission status after second-line BV. Results: Of the 20 patients enrolled to the BV dose-escalation cohort, 8 patients underwent BV dose-escalation. BV escalation was well-tolerated, but no patients who were escalated converted to CR. Of 56 evaluable patients treated across cohorts, the overall response rate (ORR) to second-line BV was 75% with 43% CR. Twenty-eight (50%) patients proceeded directly to AHCT without post-BV chemotherapy, and a total of 50 patients proceeded to AHCT. Thirteen patients received consolidative post-AHCT therapy with either radiation, BV, or a PD-1 inhibitor. After AHCT, the 2-year progression-free survival (PFS) and overall survival were 67% and 93%, respectively. The 2-year PFS among patients in CR at the time of AHCT (n = 37) was 71% compared with 54% in patients not in CR (p = 0.12). The 2-year PFS in patients who proceeded to AHCT directly after receiving BV alone was 77%. Conclusions: Second-line BV is an effective bridge to AHCT that produces responses of sufficient depth to provide durable remission in conjunction with AHCT (clinicaltrials.gov: NCT01393717).

A randomized trial of a single-dose rasburicase versus five-daily doses in patients at risk for tumor lysis syndrome.

BACKGROUND: Tumor lysis syndrome (TLS) is a life-threatening disorder characterized by hyperuricemia and metabolic derangements. The efficacy of rasburicase, administered daily for 5 days, has been well established. However, the optimal duration of therapy is unknown in adults. PATIENTS AND METHODS: We evaluated the efficacy of rasburicase (0.15 mg/kg) administered as single dose followed by as needed dosing (maximum five doses) versus daily dosing for 5 days in adult patients at risk for TLS. RESULTS: Eighty of the 82 patients enrolled received rasburicase; 40 high risk [median uric acid (UA) 8.5 mg/dl; range, 1.5-19.7] and 40 potential risk (UA = 5.6 mg/dl; range, 2.4-7.4). Seventy-nine patients (99%) experienced normalization in their UA within 4 h after the first dose; 84% to an undetectable level (<0.7 mg/dl). Thirty-nine of 40 (98%) patients in the daily-dose arm and 34 of 40 (85%) patients in single-dose arm showed sustained UA response. Six high-risk patients within the single-dose arm required second dose for UA >7.5 mg/dl. Rasburicase was well tolerated; one patient with glucose-6-phosphate dehydrogenase deficiency developed methemoglobinemia and hemolysis. CONCLUSIONS: Rasburicase is highly effective for prevention and management of hyperuricemia in adults at risk for TLS. Single-dose rasburicase was effective in most patients; only a subset of high-risk patients required a second dose.

Complete molecular remissions induced by patient-specific vaccination plus granulocyte-monocyte colony-stimulating factor against lymphoma.

Lymphomas express a tumor-specific antigen which can be targeted by cancer vaccination. We evaluated the ability of a new idiotype protein vaccine formulation to eradicate residual t(14;18)+ lymphoma cells in 20 patients in a homogeneous, chemotherapy-induced first clinical complete remission. All 11 patients with detectable translocations in their primary tumors had cells from the malignant clone detectable in their blood by PCR both at diagnosis and after chemotherapy, despite being in complete remission. However, 8 of 11 patients converted to lacking cells in their blood from the malignant clone detectable by PCR after vaccination and sustained their molecular remissions. Tumor-specific cytotoxic CD8+ and CD4+ T cells were uniformly found (19 of 20 patients), whereas antibodies were detected, but apparently were not required for molecular remission. Vaccination was thus associated with clearance of residual tumor cells from blood and long-term disease-free survival. The demonstration of molecular remissions, analysis of cytotoxic T lymphocytes against autologous tumor targets, and addition of granulocyte-monocyte colony-stimulating factor to the vaccine formulation provide principles relevant to the design of future clinical trials of other cancer vaccines administered in a minimal residual disease setting.

Prospective trial of targeted radioimmunotherapy with Y-90 ibritumomab tiuxetan (Zevalin) for front-line treatment of early-stage extranodal indolent ocular adnexal lymphoma.

BACKGROUND: To determine the efficacy and side-effects of (90)Y ibritumomab tiuxetan (Zevalin) as front-line treatment in patients with early-stage extranodal indolent lymphoma of the ocular adnexa (orbit, conjunctiva, or eyelid). PATIENTS AND METHODS: From August 2004 to November 2007, 12 patients with stages I-E extranodal indolent lymphoma of the ocular adnexa were enrolled in a prospective trial of rituximab followed by (90)Y ibritumomab tiuxetan (Zevalin therapeutic regimen). For each patient, clinical examinations and imaging studies were used to document response to therapy using the The International Working Group response criteria. All patients had (111)In ibritumomab tixuetan imaging to confirm expected biodistribution before (90)Y-Zevalin therapy; in addition, three patients had an optional single photon emission computed tomography-computed tomography scan to estimate the absorbed radiation dose to the orbital and ocular tissues. RESULTS: The study included seven women and five men. The median age was 60 years (range 22-79). Nine patients had mucosa-associated lymphoid tissue lymphoma of conjunctiva or orbit; three patients had grades 1-2 follicular lymphoma of orbit. One patient who had been deemed stage I-E initially was found to have another lesion in her deltoid muscle on positron emission tomography 2 weeks after enrollment. She was kept on trial although her disease was reclassified as stage IV due to this single additional (biopsy-proven) site. Ten patients had a complete response and two partial response (PR) within 3 months of treatment. One patient had a recurrence in the upper eyelid 6 months after an initial PR; he then received 30 Gy of external-beam radiotherapy (EBRT). His disease later progressed again in the orbit and he is currently being considered for other treatments. A second patient who attained a PR has remained stable with no progression 12 months after treatment. With a median follow-up time of 20 months (range 6-44 months), there were no cases of distant (extraorbital) relapse. All 12 patients experienced grade I or II transient pancytopenia during the first 3 months after enrollment in the trial. There were no episodes of grade III or IV myelosuppression. The estimated absorbed radiation dose to the orbital soft tissues was <3 Gy, 10 times lower than that with EBRT. CONCLUSIONS: Rituximab followed by (90)Y ibritumomab tiuxetan is an effective and safe front-line treatment for early-stage extranodal indolent B-cell lymphoma of the ocular adnexa.

H-2-linked resistance to mastocytoma in male mice: immune response to a histocompatibility antigen on the X chromosome.

Male hybrids from a cross between female mice of strain C57BL/6Kh and males of strain DBA/2J lived longer after injection of P815 mastocytoma cells of DBA/2 origin than did their female siblings. Responses to the histocompatibility antigen on the X chromosome of the DBA/2 strain may be involved in resistance to the tumor. When the female parent was replaced with a C57BL/6Kh carrying one of several mutations in the H-2 region, this sex effect disappeared in some of the hybrid combinations. Thus, the H-2 complex appears to be involved in the regulation of the immune response to the X-linked histocompatibility antigen in this tumor model.

Genetic fusion of chemokines to a self tumor antigen induces protective, T-cell dependent antitumor immunity.

We converted a model, syngeneic, nonimmunogenic tumor antigen into a vaccine by fusing it with a proinflammatory chemokine. Two chemokines, interferon inducible protein 10 and monocyte chemotactic protein 3, were fused to lymphoma Ig variable regions (sFv). The sFv-chemokine fusion proteins elicited chemotactic responses in vitro and induced inflammatory responses in vivo. Furthermore, in two independent models, vaccination with DNA constructs encoding the corresponding fusions generated superior protection against a large tumor challenge (20 times the minimum lethal dose), as compared with the best available protein vaccines. Immunity was not elicited by controls, including fusions with irrelevant sFv; fusions with a truncated chemokine that lacked receptor binding and chemotactic activity; mixtures of free chemokine and sFv proteins; or naked DNA plasmid vaccines encoding unlinked sFv and chemokine. The requirement for linkage of conformationally intact sFv and functionally active chemokine strongly suggested that the mechanism underlying these effects was the novel targeting of antigen presenting cells (APC) for chemokine receptor-mediated uptake of antigen, rather than the simple recruitment of APC to tumor by the chemokine. Finally, in addition to superior potency, these fusions were distinguished from lymphoma Ig fusions with granulocyte-macrophage colony-stimulating factor or other cytokines by their induction of critical effector T cells.

Tumor antigen-specific immunization of bone marrow transplantation donors as adoptive therapy against established tumor.

BACKGROUND: Persistence of the underlying malignancy remains the main obstacle to the successful treatment of human malignancies with high-dose chemoradiotherapy and bone marrow transplantation. PURPOSE: The aim of this study was to determine whether antigen-specific antitumor immune responses, elicited in normal donor mice by immunization with the soluble form of a surrogate tumor antigen (i.e., ovalbumin [OVA]), can be transferred via bone marrow transplantation into lethally irradiated, syngeneic recipient mice. An additional goal was to evaluate the ability of these adoptively transferred bone marrow cells to eradicate established recombinant OVA-expressing lymphomas that recurred after lethal-dose total-body irradiation (TBI). METHODS: Female C57BL/6 donor mice were immunized twice with OVA emulsified in a muramyl-dipeptide-containing adjuvant. Syngeneic mice bearing a day-10 or day-11, approximately 1-cm subcutaneous E.G7-OVA tumor (E.G7-OVA tumor cells were derived from transfection of EL-4 thymoma tumor cells using the coding sequence of chicken OVA gene complementary DNA) were treated with TBI and reconstituted with bone marrow from nonimmune or OVA-immunized mice. In subsequent experiments, tumor-bearing mice, treated with TBI and OVA-immune bone marrow, were given additional therapy either with a single OVA immunization or by the adoptive transfer of 1 x 10(7) in vitro activated spleen cells derived from OVA-immune donor mice and cultured 5 days with irradiated E.G7-OVA cells before transfer. RESULTS: E.G7-OVA tumor-bearing mice given TBI and OVA-immune bone marrow showed a significantly increased cure rate when compared with that among controls reconstituted with nonimmune bone marrow after TBI (logrank, P < .01). The antitumor effect of immune bone marrow was abrogated by T-cell depletion of the marrow graft (P < .016). The antitumor effect of immune marrow was enhanced by the addition of OVA immunization of tumor-bearing recipients (P < .015). OVA-specific cytotoxic T-lymphocyte (CTL) activity was recovered from tumor-bearing recipients of immune marrow 14 days after bone marrow transplantation. The antitumor effect observed following the adoptive transfer of immune marrow was further augmented by the addition of 1 x 10(7) splenic E.G7-OVA-specific in vitro activated CTLs derived from OVA-immune mice (P < .03). CONCLUSION: These studies establish the principle that antigen-specific T-cell immunity against a defined tumor-specific antigen can be transferred with bone marrow from an immune donor. IMPLICATIONS: Active immunization of normal human bone marrow or T-cell donors with a refined, safe tumor antigen and transfer of immunity to the patient may represent a novel strategy for circumventing the obstacle of host immune suppression associated with the tumor-bearing state.

Cytotoxic T-cell response and in vivo protection against tumor cells harboring activated ras proto-oncogenes.

BACKGROUND: Activated forms of the ras proto-oncogene have been found in approximately 30% of human malignancies, including pancreatic, colon, and lung adenocarcinomas. Ras oncoproteins arise by somatic mutation and contain amino acid changes at residues 12, 13, or 61, thus generating unique tumor-specific proteins that are attractive targets for cancer therapy. PURPOSE: The goal of this study was to determine whether vaccination with mutant Ras protein could lead to the generation of cytotoxic T lymphocytes (CTLs) specific for the mutant epitope and to protection against challenge with tumor cells expressing the mutant oncoprotein. METHODS: To determine a methodology for generating CTL responses following immunization with soluble protein, ovalbumin was used as a model tumor antigen. C57BL/6 mice were immunized with soluble ovalbumin administered intraperitoneally at 2-week intervals or with intravenous injection of ovalbumin or osmotically loaded splenocytes. Immunized mice were challenged with E.G7 cells (which express a transfected ovalbumin gene), and tumor growth was monitored. Generation of ovalbumin-specific CTLs was determined by 51Cr release assays. Purified wild-type or mutant H-Ras proteins (containing single amino acid substitutions at position 12 converting Gly to Arg or Val) were used to immunize BALB/c mice intraperitoneally. Ras-immunized mice were challenged with tumor cells containing Arg 12 or Val 12 mutations or not harboring mutant forms of Ras. Cytolytic and proliferative responses to mutant forms of Ras were studied, and the effects of in vivo depletion of CD4+ or CD8+ T lymphocytes were determined. RESULTS: In vivo challenge with E.G7 showed that intraperitoneal immunization with soluble ovalbumin was as effective as osmotic loading, resulting in long-term disease-free survival of some mice and the development of ovalbumin-specific CTLs. Immunization with Arg 12 Ras led to disease-free survival in nine of 10 animals challenged with tumor cells containing an Arg 12 mutation, while no protection was afforded against tumors expressing other forms of Ras or other oncogenes. Splenocytes from BALB/c mice immunized with Arg 12 Ras demonstrated cytolytic activity specific against tumor cells expressing Arg 12 Ras, with most of this activity residing in the CD8+ subset. Mutation-specific proliferation to Arg 12 Ras peptides was also observed. Immunization with Val 12 Ras did not elicit detectable Val 12-specific immunity. CONCLUSIONS: Antigen-specific CTLs can be induced following intraperitoneal immunization of mice with purified, soluble proteins. For both ovalbumin and Arg 12 Ras, specific in vivo protection against tumor cell challenge was observed.

Tumor resistance induced by syngeneic bone marrow transplantation and enhanced by interleukin 2: a model for the graft versus leukemia reaction.

Lethally irradiated C3H/HeN mice reconstituted with normal syngeneic bone marrow survived significantly longer than unmanipulated control mice following challenge with a lethal dose of 38C13 lymphoma cells 2 to 3 weeks post-bone marrow transplantation (BMT). Although the magnitude of this effect was modest, it was highly reproducible. This resistance-producing effect of BMT could be enhanced by interleukin 2 administration and could be abrogated by anti-asialo-GM1 antiserum treatment of recipients. These findings are consistent with the hypothesis that cells with a natural killer phenotype are activated by BMT and can mediate tumor resistance. These studies provide a model to explore the cellular basis, independent of donor alloreactivity, of the graft antitumor effect of BMT observed in humans.

H-2 gene control of resistance to P815-X2 mastocytoma.

Some, but not all, mutations at H-2 loci can alter, in either direction, histocompatible tumor resistance in the model system of P815-X2 mastocytoma (DBA/2 origin) transplanted into DBA/2J or (C57BL/6 X DBA/2J)F1 mice. This hybrid effect has been shown previously to depend on the immune system. We have examined eight mutants at H-2Kb (bm1, bm4, bm6, bm7, bm8, bm10, bm11, and bm16, two at H-2Db (bm13 and bm14), and one I-Ab mutant (bm12). When one parent is an H-2b mutant (C57BL/6 mutant), the hybrid progeny (C57BL/6 mutant X DBA/2J)F1 may have increased (bm7 and bm8) or decreased (bm10, bm11, bm12, and bm16) survival times when compared to C57BL/6 X DBA/2J)F1 controls. Hybrids from bm1, bm4, bm6 (all H-2Kb), and bm13 and bm14 (both H-2Db) mutants showed no differences in survival. Several of the mutant molecules differ from those of the parental strain by only one or two amino acids. Apparently, these small changes in H-2 antigens are capable of altering resistance to a histocompatible tumor to produce an immune response gene-like effect. The availability of H-2 mutant strains and detailed data on the molecular nature of the gene products make the model presented in this report a particularly useful system to study.

Prognostic significance of actual dose intensity in diffuse large-cell lymphoma: results of a tree-structured survival analysis.

While diffuse large-cell lymphoma (DLCL) is considered to be highly curable with current therapy, treatment failures are observed even with intensive combination chemotherapy regimens. In order to study the prognostic significance of actual dose intensity of chemotherapy in DLCL, we retrospectively analyzed 115 previously untreated patients treated as Stanford between 1975 and 1986 with cyclophosphamide, Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH), vincristine, and prednisone (CHOP), methotrexate, bleomycin, Adriamycin, cyclophosphamide, vincristine, and dexamethasone ([M]BACOD), or methotrexate, Adriamycin, cyclosphosphamide, vincristine, prednisone, and bleomycin (MACOP-B). The actual relative dose intensity (RDI), the amount of drug actually administered to each patient during the first 12 weeks of therapy, was calculated as standardized to CHOP and analyzed in addition to clinical factors prognostic for survival by univariate analysis. Multivariate recursive partitioning (tree-structured) survival analysis identified the actual RDI of Adriamycin greater than 75% as the single most important predictor of survival. A model incorporating the actual RDI of Adriamycin and performance status, in combination with serum lactate dehydrogenase (LDH) and extranodal disease, defined three overall prognostic groups of patients with respective 3-year survival rates of 89%, 63%, and 18%. The three prognostic groups remained distinct, even when restricted to complete responders. This model was also predictive of survival when dose intensity was analyzed relative to the optimum dose defined for each of the three regimens and when applied to a subgroup of patients aged 50 years or younger. We conclude that actual RDI is an important prognostic factor for survival in DLCL and that analysis of RDI early in the course of treatment may allow modification of the treatment plan.

Clinical trial designs for the early clinical development of therapeutic cancer vaccines.

There are major differences between therapeutic tumor vaccines and chemotherapeutic agents that have important implications for the design of early clinical trials. Many vaccines are inherently safe and do not require phase I dose finding trials. Patients with advanced cancers and compromised immune systems are not good candidates for assessing either the toxicity or efficacy of therapeutic cancer vaccines. The rapid pace of development of new vaccine candidates and the variety of possible adjuvants and modifications in method of administration makes it important to use efficient designs for clinical screening and evaluation of vaccine regimens. We review the potential advantages of a wide range of clinical trial designs for the development of tumor vaccines. We address the role of immunological endpoints in early clinical trials of tumor vaccines, investigate the design implications of attempting to use disease stabilization as an end point and discuss the difficulties of reliably utilizing historical control data. Several conclusions for expediting the clinical development of effective cancer vaccines are proposed.

Similar outcome of treatment of B-cell and T-cell diffuse large-cell lymphomas: the Stanford experience.

Although previous studies have suggested a relatively poor prognosis for some patients with peripheral T-cell lymphoma, the clinical significance of immunologic phenotype in diffuse large-cell lymphoma (DLCL) remains controversial. One hundred one patients with a uniform morphologic diagnosis of DLCL treated at Stanford between 1975 and 1986 with cyclophosphamide, Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH), vincristine, and prednisone (CHOP), methotrexate, bleomycin, Adriamycin, cyclophosphamide, vincristine, and dexamethasone ([M]BACOD), or methotrexate, Adriamycin, cyclophosphamide, vincristine, prednisone, and bleomycin (MACOP-B) chemotherapy were studied with regard to immunologic phenotype. Immunologic analysis, performed on frozen or paraffin-embedded tissue, identified 77 cases of B-cell origin, 21 cases of T-cell origin, and three cases that lacked B-cell or T-cell markers. Analysis of complete remission (CR) rates (84% v 95%), 5-year actuarial freedom from disease progression (38% v 53%), and 5-year actuarial overall survival (52% v 79%) showed no statistically significant differences in prognosis between B- and T-cell patients, respectively. The 5-year actuarial survival of patients with stage IV T-cell DLCL (56%) also did not differ in a statistically significant way from stage IV B-cell patients (36%). We conclude that treatment selection for DLCL should not be based on immunologic phenotype alone.

Tumor antigen immunization of sibling stem cell transplant donors in multiple myeloma.

The unique antigenic determinants (idiotype (Id)) of the immunoglobulin secreted by myeloma tumor can serve as a tumor-specific antigen for active immunotherapy. Our objective was to induce tumor-specific T-cell immunity in bone marrow transplant (BMT) donors to enhance antitumor effects of allografts. We vaccinated five HLA-matched sibling donors with myeloma Id proteins isolated from recipient plasma before bone marrow harvest. Recipients were administered booster Id immunizations following transplantation. Vaccination induced donor Id and carrier-specific cellular and/or humoral immune responses. Two recipients died within 30 days of BMT from transplant-related complications. Id and carrier-specific T-cell responses were detected in all three remaining patients post-, but not pre-BMT and persisted for 18 months. All three surviving patients converted from partial to complete responses following BMT. Two of the three patients remain disease-free 7 years and 8 years after BMT, and the third died of renal failure after 5.5 years while in complete remission from myeloma. Our results suggest that myeloma Id vaccination induces specific T-cell immunity in healthy donors which may be transferable by BMT, is associated with prolonged disease-free survival of recipients, and may represent a general strategy to enhance graft-versus-tumor effect in other malignancies for which defined tumor-specific antigens exist.

Detection of tumor messenger RNA in the serum of patients with malignant melanoma.

Serum RNases are known to be elevated in patients with cancer. Consequently, it is not clear whether human mRNA with sufficient integrity as to permit reverse transcription-PCR (RT-PCR) amplification is detectable in serum. We examined serum from six patients with malignant melanoma for human tyrosinase mRNA using RT-PCR. Serum from 20 normal volunteers served as controls. Tyrosinase mRNA could be demonstrated in serum from four of the six melanoma patients with detection by gel electrophoresis and confirmation by blotting amplified product to a tyrosinase-specific probe. The serum remained tyrosinase mRNA positive, even if passed through a 0.45 microm filter prior to RNA extraction, indicating that the mRNA was extracellular at the time of extraction. Tyrosinase mRNA could not be detected in any control serum (0 of 20 individuals). The presence and integrity of amplifiable RNA was confirmed in all serum specimens (patients and controls) by RT-PCR amplification of c-abl mRNA. Amplifiable RNA could be demonstrated regardless of whether serum was freshly drawn or stored frozen for several years. We conclude that human mRNA can be extracted and amplified from serum. The ability to amplify tumor mRNA from serum may have important utility in cancer diagnostics and monitoring.

Immunotherapy of multiple myeloma.

The failure of chemotherapy to cure a significant proportion of multiple myeloma (MM) patients and increasing knowledge of tumor immunology and MM biology have generated considerable interest in immunotherapy for this lethal disease. Immunotherapy for MM can be divided into three broad categories: passive antibody-mediated immunotherapy, active specific immunization (vaccination), and adoptive T-cell immunotherapy. Early clinical trials using anti-CD20 monoclonal antibodies (mAbs) have met with limited success so far but have also suggested that selected patient subgroups may benefit from this treatment. The availability of a truly tumor-specific antigen such as immunoglobulin idiotype, the recent demonstration that MM cells process and present idiotype to T lymphocytes, and formal evidence of an antitumor effect of idiotypic vaccination in follicular lymphoma provide the framework for applying idiotypic vaccination in MM. The ability to generate ex vivo functional dendritic cells has made it possible to fuse them with patients' MM cells, thus producing a different type of customized vaccine. Dendritic cells are also a pivotal reagent to generate ex vivo MM-specific cytotoxic T lymphocytes (CTLs) to be reinfused into the patient for adoptive immunotherapy. This review summarizes achievements in MM immunotherapy based on data reported since 1998.

Idiotypic vaccination as therapy for multiple myeloma.

Although advances in the treatment of multiple myeloma have been made using high-dose chemotherapy with subsequent autologous stem-cell transplantation, recurrence of the underlying disease almost invariably occurs. One proposed strategy to increase survival is tumor-specific activation of the immune system via idiotypic protein vaccination. Current issues to be resolved in the development of this approach include optimal vaccine formulation, appropriate assays to monitor treatment results, and timing of vaccine administration. Several clinical trials of idiotypic vaccines are currently being conducted in the United States and Europe. Initial results support the use of these vaccines as adjunct therapy in patients with multiple myeloma after high-dose chemotherapy and transplantation.

Blood levels of organochlorines before and after chemotherapy among non-Hodgkin's lymphoma patients.

Several small studies suggest a link between environmental exposure to organochlorine compounds and risk of non Hodgkin's lymphoma (NHL). Because NHL is uncommon, studies of the topic often use a population-based case-control design, in which cases generally are enrolled after treatment has begun. If chemotherapy affects blood levels of organochlorines, exposure will be misclassified and findings distorted. To determine whether chemotherapy alters serum levels of organochlorines in NHL cases, we compared serum samples before and after treatment in 22 cases diagnosed with NHL between March 1994 and August 1995 and enrolled in a clinical trial at the United States National Cancer Institute's Clinical Center. The time difference between pretreatment and posttreatment samples ranged from 15 to 27 months with an average of 20 months. Laboratory analyses were conducted in blinded pretreatment and posttreatment pairs of the subjects. Pretreatment and posttreatment organochlorine serum levels were compared using Pearson correlation coefficient (r) and paired t test. The pretreatment and posttreatment serum levels were highly correlated for 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) and polychlorinated biphenyls (PCBs) PCB-138, PCB-153, PCB-156, and total PCBs (ranging from 0.78 to 0.93). Serum levels of all of these organochlorines significantly decreased between initiation and completion of chemotherapy, 25% for total PCB (P = 0.0044), 28% for DDE (P = 0.0014), 25% for PCB-138 (P = 0.0053), 27% for PCB-153 (P = 0.0031), and 29% for PCB-156 (P = 0.045). Neither weight change nor lipid change was correlated with changes in chemical levels. There was no association between the length of time between blood draws and changes in chemical levels. Our data raise the possibility that lymphoma treatment depresses serum organochlorine levels.

Radiation-induced augmentation of host resistance to histocompatible tumor in mice. Detection of a graft antitumor effect of syngeneic bone marrow transplantation.

Lethally irradiated and syngeneic bone marrow-reconstituted (C57BL/6JxDBA/2J) F1 female mice demonstrated prolonged survival following challenge with the DBA/2 mastocytoma P815-X2 compared with non-irradiated littermate controls. This radiation-induced augmentation of host resistance to P815-X2 was not abolished by the adoptive transfer of normal syngeneic spleen cells. In addition, this phenomenon was not detectable in adult thymectomized recipients, suggesting the requirement for an intact host thymus. This effect was also absent in syngeneic F1 male recipients. We suggest that lethal irradiation and marrow reconstitution may result in activation of a nonspecific immune effector mechanism against tumor cells--and, as such, may serve as a model to explore the graft-antitumor effect of bone marrow transplantation.