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).

FAS-antisense 1 lncRNA and production of soluble versus membrane Fas in B-cell lymphoma

Impaired Fas-mediated apoptosis is associated with poor clinical outcomes and cancer chemoresistance. Soluble Fas receptor (sFas), produced by skipping of exon 6, inhibits apoptosis by sequestering Fas ligand. Serum sFas is associated with poor prognosis of non-Hodgkin's lymphomas. We found that the alternative splicing of Fas in lymphomas is tightly regulated by a long-noncoding RNA corresponding to an antisense transcript of Fas (FAS-AS1). Levels of FAS-AS1 correlate inversely with production of sFas, and FAS-AS1 binding to the RBM5 inhibits RBM5-mediated exon 6 skipping. EZH2, often mutated or overexpressed in lymphomas, hyper-methylates the FAS-AS1 promoter and represses the FAS-AS1 expression. EZH2-mediated repression of FAS-AS1 promoter can be released by DZNeP (3-Deazaneplanocin A) or overcome by ectopic expression of FAS-AS1, both of which increase levels of FAS-AS1 and correspondingly decrease expression of sFas. Treatment with Bruton's tyrosine kinase inhibitor or EZH2 knockdown decreases the levels of EZH2, RBM5 and sFas, thereby enhancing Fas-mediated apoptosis. This is the first report showing functional regulation of Fas repression by its antisense RNA. Our results reveal new therapeutic targets in lymphomas and provide a rationale for the use of EZH2 inhibitors or ibrutinib in combination with chemotherapeutic agents that recruit Fas for effective cell killing.

Lenalidomide enhances the protective effect of a therapeutic vaccine and reverses immune suppression in mice bearing established lymphomas

Immunomodulatory drugs (IMiDs) are effective therapeutic agents with direct inhibitory effects on malignant B- and plasma-cells and immunomodulatory effects on the T-cell activation. This dual function of IMiDs makes them appealing candidates for combination with a cancer vaccine. We investigated the immune stimulatory effects of lenalidomide, administrated to mice in doses, which provided comparable pharmacokinetics to human patients, on the potency of a novel fusion DNA lymphoma vaccine. The combination was curative in the majority of mice with 8d pre-established syngeneic A20 lymphomas compared with vaccine or lenalidomide alone and induced immune memory. In vivo depletion experiments established the requirement for effector CD8(+) and CD4(+) T cells in protective immunity. Unexpectedly, lenalidomide alone was also associated with reduced numbers of systemic myeloid-derived suppressor cell (MDSC) and regulatory T cell (Treg) in tumor-bearing but not naïve mice, an effect that was independent of simple tumor burden reduction. These results confirm and extend results from other models describing the effect of lenalidomide on enhancing T-cell immunity, highlight the potency of this effect, and provide a rationale for clinical application. Independently, a novel mechanism of action reversing tumor-induced immune suppression by MDSC is suggested.

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.

Idiotype vaccine therapy (BiovaxID) in follicular lymphoma in first complete remission: Phase III clinical trial results

2

Background: In previous trials, tumor-specific purified idiotype (Id) protein conjugated to keyhole limpet hemocyanin (KLH) administered with granulocyte-monocyte colony-stimulating factor (GM-CSF) induced follicular lymphoma (FL)-specific immune responses and molecular remissions (Nat Med. 1999;5:1171–7). Methods: We conducted a prospective randomized double-blind placebo-controlled multicenter phase III study of patient-specific autologous tumor-derived Id vaccine in advanced stage previously untreated FL patients (pts) with a lymph node adequate for vaccine production (≥ 2cm). Pts achieving complete response (CR) or complete response unconfirmed (CRu) after chemotherapy (PACE: prednisone, doxorubicin, cyclophosphamide, etoposide) were stratified by International Prognostic Index risk group and randomized 2:1 to receive either vaccination with Id-KLH/GM-CSF or control (KLH/GM-CSF). The primary endpoint was disease free survival. Results: 234 pts were enrolled; 177 (76%) achieved CR/CRu and were randomized. Of 177 randomized pts, 117 maintained CR/CRu ≥ 6 mo per protocol requirement and then received at least one dose of vaccine, 55 relapsed before vaccination, 4 were vaccine manufacturing failures, and 1 violated protocol. Pts who received ≥ one vaccine dose constituted the modified intent-to-treat population for determination of efficacy. 76 pts received Id-KLH/GM-CSF and 41 pts received the control (KHL/GM-CSF). No serious adverse events were attributed to Id vaccination. At a median follow-up of 56.6 mo (range 12.6 –89.3 mo), median time to relapse after randomization for the Id-KLH/GM-CSF arm was 44.2 mo, versus 30.6 mo for the control arm (p = 0.045; HR = 1.6). Conclusions: Id vaccination after a chemotherapy-induced remission of ≥ 6 mo prolongs remission duration in pts with FL. Compared to other phase III Id vaccine trials, the positive outcome of this study may reflect application of Id vaccine in pts in CR/CRu or use of hybridomas to produce Id. Genomic and immune response analyses are planned on residual autologous tumor and blood samples. Additional studies of this patient-specific vaccine in FL pts pretreated with anti-CD20 antibody-containing chemotherapy are indicated.

[Table: see text]

Sibling donor immunization with patient-derived Id-KLH vaccine prior to reduced-intensity allogeneic hematopoietic cell transplantation for multiple myeloma

7024

Background: Relapse is the most common cause of treatment failure after reduced-intensity allogeneic hematopoietic cell transplantation (RI-alloHCT) for multiple myeloma (MM). To enhance graft-versus-myeloma effects, we investigated the use of patient-specific idiotype (Id) vaccine in both donors and recipients. Methods: Id protein was obtained by plasmapheresis and conjugated to keyhole limpet hemocyanin (Id-KLH) to generate vaccine. Donors received 3 SQ injections of Id-KLH + GM-CSF at 10, 8, and 4 weeks before stem cell donation. MM pts received a reduced-intensity conditioning regimen (Flu/Cy) and GVHD prophylaxis consisted of cyclosporine plus methotrexate. MM pts were vaccinated with the Id-KLH+GM-CSF at 3, 4, and 6 months post-transplant. Humoral responses were determined by ELISA and Th1 (IL-2, IFN-γ, TNF-α, and GM-CSF) and Th2 (IL-4, IL-5, IL-10, and IL-13) cellular immune responses against Id and KLH were determined by multiplex cytokine assay. Results: Ten MM pts (median age: 54 years; IgG = 8, IgA = 2) and their respective donors were enrolled onto study. All 10 donors completed vaccinations without significant complications. Following vaccination, KLH-specific antibody and Th1/Th2 responses were noted in all 10 donors. Id-specific antibody responses were noted in 6 donors; Th1 and Th2 responses were noted in 5 and 6 donors, respectively. All 10 MM pts underwent RI-alloHCT; the median potential follow-up post-transplant is 43.8 months. Id-specific Th1 and Th2 responses were noted in 5 and 3 pts, respectively, prior to post-transplant immunization; antibody response was noted in 1 patient. Nine evaluable MM pts completed their post-transplant vaccinations. KLH-specific antibody and Th1/Th2 responses were detectable in all 9 pts post-transplant. Id and KLH immune responses were further enhanced by post-transplant vaccinations. Median progression-free survival is 27.3 months; median survival has not been reached. Conclusions: The data suggest Id-specific immunity can be safely induced in normal stem cell donors and passively transferred to recipients of RI-alloHCT. Donor vaccination with tumor-specific antigen represents a tactic to potentially reduce relapse after RI-alloHCT.

No significant financial relationships to disclose.

Idiotype vaccine therapy (BiovaxID) in follicular lymphoma in first complete remission: Phase III clinical trial results

2

The full, final text of this abstract will be available in Part II of the 2009 ASCO Annual Meeting Proceedings, distributed onsite at the Meeting on May 30, 2009, and as a supplement to the June 20, 2009, issue of the Journal of Clinical Oncology.

[Table: see text]

Bortezomib is synergistic with rituximab and cyclophosphamide in inducing apoptosis of mantle cell lymphoma cells in vitro and in vivo

Mantle cell lymphoma (MCL) is an aggressive B-cell lymphoma with poor clinical outcome. Although front therapy induces a high rate of complete remission (CR), relapse is inevitable and new regimens are much needed for relapsed MCL. The proteasome inhibitor bortezomib (BTZ) induces apoptosis and sensitizes MCL cells to chemotherapy in relapsed MCL, but CR rates are low, with a short duration of response and severe toxicity. Here we evaluated whether BTZ is additive or synergistic with cyclophosphamide (CTX) and rituximab (RTX). Increasing doses of BTZ with a fixed dose of RTX and CTX (BRC regimen) resulted in markedly synergistic growth inhibition of MCL cells. BRC significantly enhanced apoptosis in MCL cell lines and primary tumor cells compared with single-agent treatment. Furthermore, western blotting analysis indicated that BRC induces apoptosis earlier via activation and cleavage of caspases-8, -9 and -3, and poly (ADP-ribose) polymerase, than single-agent treatment. The pan-caspase inhibitor completely blocked apoptosis induced by BRC. In vivo studies showed that BRC eradicated subcutaneous tumors in MCL-bearing SCID mice and significantly prolonged the long-term event-free survival in 70% of the mice. Hence, our study demonstrates that cytoreductive chemotherapy with both BTZ and anti-CD20 antibody may offer a better therapeutic modality for relapsed MCL.

Idiotype vaccine therapy of follicular lymphoma in first remission: Association of t(14;18) and disease free survival in a phase II cohort

7582

Background: A single-arm Phase 2 study (Nature Med 5:1171–7,1999), evaluated the ability of tumor-specific idiotype (Id) conjugated to keyhole limpet hemocyanin (KLH) administered with granulocyte-monocyte colony-stimulating factor - GM-CSF (BiovaxID vaccine) to induce complete remission (CR) and molecular remission (MR) in follicular NHL patients in first CR after chemotherapy. We reported (ASH 2005, Abstr 2441) that at 9.2 years follow-up, disease free survival (DFS) and overall survival (OS) were 45% and 95%, respectively; median DFS was 8.0 years. Previous studies indicated that the t(14;18) chromosomal translocation is associated with follicular NHL. We tested the hypothesis that absence of t(14;18) in peripheral blood (PB) of patients after Id vaccination is predictive of DFS. Methods: A 20-patient cohort in first CR treated with the vaccine was evaluated. t(14;18)- (MR) is defined as <1 t(14;18)+ cell in 105 cells using PCR of the MBR breakpoint cluster on DNA from tumor biopsies or PB. Of the 20 patients, 11 had t(14;18)+ tumors and PB before chemotherapy. Following chemotherapy all 11 patients continued to have t(14;18)+ PB despite being in CR. However, at 1 month following final vaccine treatment, 8 of these patients had converted to t(14;18)- . In this ad hoc analysis, the proportion of patients remaining in DFS was stratified by t(14;18) status; Kaplan-Meier analysis compared median DFS of patients across t(14;18) status following vaccination. Results: At median follow-up of 9.2 years, 55% of patients had clinically relapsed. Although not statistically significant, of the 17 patients t(14;18)- post-vaccine, only 47.1% had clinically relapsed while 100% of the 3 t(14;18)+ patients had relapsed [Chi-square test; P=0.089]. Median DFS in t(14;18)+ patients was 60 months (5.0 years) and had not yet been reached in t(14;18)- patients at 91 months (7.6 years) [Log-rank test; P=0.069]. Conclusions: These data show a possible association between t(14;18) negativity following vaccine and prolonged DFS. Additional follow-up on these patients is needed, as well as similar analyses in other cohorts, to further explore this association.

[Table: see text]

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.

Roles of antimicrobial peptides such as defensins in innate and adaptive immunity

A number of antimicrobial peptides such as defensins have multiple functions in host defence. Defensins are produced not only by phagocytic cells and lymphocytes, but also by the epithelial cell lining of the gastrointestinal and genitourinary tracts, the tracheobronchial tree, and keratinocytes. Some are produced constitutively, whereas others are induced by proinflammatory cytokines and exogenous microbial products. Defensins produced by cells in the course of innate host defence serve as signals which initiate, mobilise, and amplify adaptive immune host defences. Administration of defensins with antigens to mice enhances both cellular (Th1-dependent) and humoral (Th2-dependent) cytokine production and immune responses. Linkage of defensins to weak tumour antigens potentiates their immunoadjuvant effects. Defensins use multiple cellular receptors, which endows them with the capacity to marshall adaptive host defences against microbial invaders.

Recent advances in multiple myeloma immunotherapy

Multiple myeloma (MM) responds to, but is not cured by, chemotherapy and may therefore be amenable to tumor-specific immunization in the setting of minimal residual disease. The idiotype of the monoclonal immunoglobulin expressed by the tumor provides a clear tumor-specific antigen. Patients with follicular lymphoma have unequivocally established that idiotypic vaccination, administered when patients have minimal residual disease, has an antitumor effect and potential to improve the clinical outcome. This result and preclinical studies demonstrating that MM cells display idiotypic peptides on their surface in a form suitable for recognition and killing by host T cells, foster the application of idiotypic vaccination in MM. The current vaccine production involves idiotype protein purification for each patient followed by conjugation to exogenous, immunogenic carriers in order to break immunological tolerance. Furthermore, recent advances in molecular cloning and development of novel antigen delivery systems are making it possible to streamline the production of equally or more effective idiotypic vaccines. Particularly, DNA vaccines utilising genetic carriers to target idiotype on dendritic cells in vivo have proven successful in preclinical models. Additional candidate T cell antigens, such as MUC1, the cancer-testis antigens, and telomerase have been identified as potential targets for immunization. The possibility of using whole myeloma cells as a source of tumor antigens for immunotherapy is also being actively explored. Finally, clinical studies have begun in which dendritic cells are generated ex vivo, loaded with tumor antigen(s), and reinfused to immunize patients.

Mediators of innate immunity that target immature, but not mature, dendritic cells induce antitumor immunity when genetically fused with nonimmunogenic tumor antigens

Chemokine receptors are differentially expressed on immature and mature dendritic cells (DC). Herein, we demonstrate for the first time that murine antimicrobial peptides beta-defensins 2 and 3 bind murine CCR6, similarly to inflammatory chemokine macrophage-inflammatory protein 3alpha, and they chemoattract bone marrow-derived immature, but not mature DC. Using various chemokines or defensins fused with nonimmunogenic tumor Ags, we studied their capacity to delivery Ags to subsets of immune cells to elicit antitumor immunity. We demonstrate that DNA immunizations with fusion constructs with beta-defensin 2 or inflammatory chemokines that target immature DC, but not homeostatic chemokines secondary lymphoid tissue chemokine, CCL21, or stromal cell-derived factor 1, CXCL12, which chemoattract mature DC, elicit humoral, protective, and therapeutic immunity against two different syngeneic lymphomas.

Detection of keyhole limpet hemocyanin (KLH)-specific immune responses by intracellular cytokine assay in patients vaccinated with idiotype-KLH vaccine

Keyhole limpet hemocyanin (KLH) has been used as an immune potentiator to enhance antigen-specific responses against haptens and weak antigens including self-antigens. In the present study, we describe the optimization of the intracellular cytokine response to KLH in peripheral blood mononuclear cells (PBMC) of lymphoma and myeloma patients that were vaccinated with tumor-specific immunoglobulin (Id) conjugated to KLH. Addition of anti-CD28 antibody significantly enhanced cytokine-producing CD4-T cells. While fresh PBMC showed maximal cytokine response 14 h after antigen stimulation, the frozen PBMC showed maximal cytokine responses by 24 h. Supplementation of the culture medium with fetal bovine serum gave a better signal-to-noise ratio than human AB serum in the intracellular detection of cytokines. The intracellular cytokine responses correlated with the cytokine measurements by enzyme-linked immunosorbent assay (ELISA). Together these results indicate that the intracellular cytokine assay is very helpful to measure antigen-specific immune responses, and in subsequent studies, we have utilized this sensitive technique to detect immune responses against tumor antigens such as idiotype.

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.

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.

Tumor-specific recognition of human myeloma cells by idiotype-induced CD8(+) T cells

Immunoglobulin secreted by myeloma cells contains a unique antigenic determinant (idiotype [Id]) that may serve as a tumor-specific antigen. Although Id-protein-specific T-cell responses have been reported in patients with myeloma, it is not known whether primary myeloma tumor cells can present naturally processed Id peptides on their surface as a target. We immunized 2 healthy human stem-cell donors with Id proteins from their recipients. T cells from the immunized donors released high levels of T-helper 1-type cytokines in response to stimulation with myeloma cells from their recipients. The T-cell-mediated cytokine response to tumor cells was blocked by a major histocompatibility complex (MHC) class I monoclonal antibody, whereas the response to soluble Id protein was dependent on MHC class II. To investigate whether Id-specific CD8(+) T cells can recognize and kill autologous myeloma cells, we generated T cells from peripheral blood mononuclear cells from a third patient with myeloma by means of in vitro stimulation with autologous dendritic cells pulsed with Id protein. Tumor-specific lysis of myeloma cells was demonstrated by the lack of killing of autologous nonmalignant B cells or natural killer-sensitive K562 cells. Lysis of autologous myeloma targets was restricted by MHC class I molecules. These data represent the first report of class I-restricted T-cell recognition of fresh autologous myeloma targets and formally demonstrate that human myeloma cells can serve as targets of an Id-specific T-cell response. (Blood. 2000;96:2828-2833)

Serum BCL2/IGH DNA in follicular lymphoma patients: a minimal residual disease marker

The majority of follicular lymphoma patients carry a t(14,18) juxtaposing the BCL2 oncogene to the immunoglobulin heavy chain joining region (IgH). Molecular analysis for follicular lymphoma-specific DNA translocations may permit evaluation of minimal residual disease (MRD). We identify extracellular BCL2/IGH transgene DNA in the serum of patients with follicular lymphoma, and evaluate its utility as a surrogate marker. DNA was harvested from both the sera and bone marrow of 5 stage IV follicular lymphoma patients prior to and after chemotherapy and following a novel vaccine-based regimen. Serial PCR amplifications were performed using heminested BCL2-specific major breakpoint cluster region (MBR) primers and the immunoglobulin heavy chain consensus primer. Amplification products were detected by agarose gel electrophoresis, and comparison was made to amplification products from the original tumor biopsy. Results show that four of the five lymphoma patients carried extracellular BCL2/IGH transgene DNA in their serum. The remaining patient did not have an amplification product from either the tumor or the serum, suggesting either the absence of a translocation or the presence of a variant translocation not detectable with this primer set. Transgene DNA was detectable in serum even in patients with MRD, comparing favorably with bone marrow results. In at least one patient, the presence of the transgene in serum at the conclusion of therapy preceded relapse. In conclusion, it seems that tumor-specific, extracellular DNA is present in the serum of follicular lymphoma patients, including those with MRD. Because extracellular DNA may be released into the bloodstream by tumor throughout the body it may be less subject to sampling error, and appears to be an ideal surrogate marker.

Defensins act as potent adjuvants that promote cellular and humoral immune responses in mice to a lymphoma idiotype and carrier antigens

Defensins released by neutrophils are able to kill a broad spectrum of microbes. They also induce leukocyte migration in vitro and elicit inflammatory leukocyte responses at s.c. injection sites in mice. In vitro experiments showed that human defensins enhanced concanavalin A-stimulated murine spleen cell proliferation and IFN-gamma production. This led us to examine the effects of human defensins on specific immune responses in vivo. BALB/c mice were immunized with 50 microg of keyhole limpet hemocyanin (KLH) adsorbed to aluminum hydroxide and administered with defensins in aqueous solution. Intraperitoneal administration of defensins significantly increased the production of KLH-specific IgG1, IgG2a and IgG2b antibodies 14 days after immunization. In vitro splenic KLH-specific proliferative responses were higher in mice treated with KLH and defensins than in those treated with KLH alone. Increased IFN-gamma and, to a lesser extent, IL-4 production were also detected in the supernatants of ex vivoKLH-activated spleen cells from mice treated with defensins. Finally, defensins significantly enhanced the antibody response to a syngeneic tumor antigen, lymphoma Ig idiotype and also augmented resistance to tumor challenge. These results indicate that defensins act as potent immune adjuvants by inducing the production of lymphokines, which promote T cell-dependent cellular immunity and antigen-specific Ig production. Thus, defensins appear to function as neutrophil-derived signals that promote adaptive immune responses.

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.

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.

B-cell malignancies as a model for cancer vaccines: from prototype protein to next generation genetic chemokine fusions

B-cell malignancy-derived Ig may be considered a model tumor antigen for vaccine development. However, as a non-immunogenic self antigen, it must also be first rendered immunogenic by chemical or genetic fusion to carriers which enable the induction of protective antitumor immunity in murine tumor models. Our group has demonstrated that active immunizations of human patients with idiotypic vaccines elicited antigen-specific CD8+ T-cell responses and antitumor effects. Several alternative preclinical strategies to develop vaccines have been previously reported, including fusion of tumor idiotype-derived single chain Fv with cytokines and immunogenic peptides. On the other hand, we have recently explored a different approach in which the model antigen is rendered immunogenic in mice by genetically fusing it to a chemokine moiety. Administration of these vaccines as fusion proteins or naked DNA vaccines may allow efficient targeting of antigen-presenting cells in vivo. Potent antitumor immunity was dependent on the generation of specific anti-idiotypic antibodies and both CD4+ and CD8+ effector T cells. We propose that chemokine fusion may represent a novel, general strategy for formulating existing or newly identified tumor and HIV antigens into vaccines for cancer and AIDS, respectively, which elicit potent CD8+ T-cell immunity.

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.

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.

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.

Tumor vaccination strategies combined with autologous peripheral stem cell transplantation

Despite advances in high-dose therapy with autologous stem cell transplantation for lymphomas, relapse of the underlying disease remains a significant obstacle. Recent advances in cancer vaccine development, specifically, the molecular identification of novel tumor antigens and understanding of cellular signals delivered by cytokines and costimulatory molecules required for efficient T-cell activation, now make it possible to consider combining active specific immunotherapy with PSCT as a strategy for elimination of minimal residual disease. As a model lymphoma-specific antigen, vaccination with patient-specific, immunoglobulin idiotype has been shown to be therapeutically effective when combined with marrow transplantation in small animal models. These preclinical studies predict the feasibility of immunization of human patients with B-cell malignancies vaccinated with this antigen in the post-transplant setting in ongoing clinical trials, especially for T-cell responses. In the future, other vaccine formulations, based on gene therapy approaches to enhance the immunogenicity of whole lymphoma cells or the identification of novel, defined antigens selectively expressed on lymphoma cells, as well as combined strategies of pre- and post-transplant tumor vaccination are envisioned.

Liposomal formulation of a self lymphoma antigen induces potent protective antitumor immunity

We developed a liposome carrier for a model nonimmunogenic, self Ag. This carrier reproducibly converted lymphoma Ig into a potent tumor rejection Ag in mice. A single immunization induced protection against challenges representing 20 to 100 times the minimum lethal dose of parental tumor. This protective effect required minimal amounts of incorporated Ag and IL-2 and elicited specific Abs (compared with free Ag or liposomal control Ig which did not elicit any specific Abs); depletion experiments demonstrated a requirement for effector CD4+ and CD8+ T cells. Head-to-head comparisons, indicating superior potency and induction of specific T cell activation, distinguished liposomal from prototype, carrier-conjugated Ag. These results provide a strategy for formulating weak tumor or other clinically important Ags into vaccines.

Tumor-specific idiotype vaccines in the treatment of patients with B-cell lymphoma--long-term results of a clinical trial

The surface Ig on each B-cell lymphoma has unique portions (idiotypes), which can be recognized by the immune system. In this study, we immunized patients against the Ig expressed by their tumor and observed their clinical outcomes. After standard chemotherapy, 41 patients with non-Hodgkin's B-cell lymphoma received a series of injections with a vaccine consisting of tumor Ig protein coupled to keyhole limpet hemocyanin and emulsified in an immunologic adjuvant. Subjects were observed for toxicity, immune responses, and tumor status. The median duration of follow-up of all patients is 7.3 years from diagnosis and 5.3 years from the last chemotherapy given before vaccine treatment. Twenty patients (49%) generated specific immune responses against the idiotypes of their tumor Ig. Two patients who had residual disease experienced complete tumor regression in association with the development of these immune responses. The median duration of freedom from disease progression and overall survival of all 20 patients mounting an anti-idiotype immune response are significantly prolonged compared to the patients who did not mount an immune response. Thirty-two patients were in their first remission and nine were in subsequent remissions before beginning vaccine treatments. Analysis of the 32 first remission patients also shows an improved clinical outcome for those patients who mounted a specific immune response compared to those who did not (freedom from progression, 7.9 years v 1.3 years P = .0001; median survival from time of last chemotherapy not yet reached v 7 years, P = .04). This study confirms an earlier report that patients with B-cell lymphoma can be induced to make a specific immune response against the Ig expressed by their own tumor. It further shows that the ability to make such an immune response is correlated with a more favorable clinical outcome. Prospective controlled trials will be needed to prove a causal relationship between anti-idiotype immunity and improved clinical outcome.

Adoptive transfer of anti-CD3-activated CD4+ T cells plus cyclophosphamide and liposome-encapsulated interleukin-2 cure murine MC-38 and 3LL tumors and establish tumor-specific immunity

The infusion of anti-CD3-activated murine T cells plus interleukin-2 (IL-2) exerts antitumor effects against several tumors in murine immunotherapy models. This study compares the therapeutic efficacy of anti-CD3-activated CD4+ or CD8+ T-cell subsets, when given with cyclophosphamide (Cy) and liposome-encapsulated IL-2 (L-IL2) in a murine model. C57BL/6 mice bearing subcutaneous (S.C.) MC-38 colon adenocarcinoma, 3LL Lewis lung carcinoma, or 38C13 lymphoma for 7 to 14 days were pretreated with low-dose intraperitoneal (I.P.) Cy before intravenous (I.V.) injection of anti-CD3-activated T cells or T-cell subsets. Cell administration was followed by I.P. administration of L-IL2 for 5 days. Mice receiving activated CD4+ T cells showed significantly reduced tumor growth or complete remissions with prolonged disease-free survival in MC-38, 3LL, and 38C13. The timing of Cy doses in relation to adoptive transfer was critical in obtaining the optimal antitumor effect by CD4+ cells. Injecting Cy 4 days before the infusion of CD4+ cells greatly enhanced the antitumor effect of the CD4+ cells and improved survival of the mice compared with other Cy regimens. C57BL/6 mice cured of MC-38 after treatment with CD4+ T cells developed tumor-type immunologic memory as demonstrated by their ability to reject rechallenges with MC-38, but not 3LL. Similarly, mice cured of 3LL tumors rejected rechallenges of 3LL, but not MC-38. The immunologic memory could be transferred with an I.V. injection of splenocytes from mice cured of MC-38 or 3LL. No cytotoxic T-lymphocyte activity was detected in T cells or T-cell subsets from mice cured of MC-38 or 3LL. Increased IL-2 and interferon-gamma (IFN-gamma) production was observed from CD4+ subsets in cured animals when stimulated in vitro with the original tumor, but not with an unrelated syngeneic tumor. These results suggest that tumor-specific immunity can be achieved in vivo with anti-CD3-stimulated CD4+ T cells in this cellular therapy model.

Vaccination with syngeneic, lymphoma-derived immunoglobulin idiotype combined with granulocyte/macrophage colony-stimulating factor primes mice for a protective T-cell response

The idiotype of the Ig expressed by a B-cell malignancy (Id) can serve as a unique tumor-specific antigen and as a model for cancer vaccine development. In murine models of Id vaccination, formulation of syngeneic Id with carrier proteins or adjuvants induces an anti-idiotypic antibody response. However, inducing a potent cell-mediated response to this weak antigen instead would be highly desirable. In the 38C13 lymphoma model, we observed that low doses of free granulocyte/macrophage colony-stimulating factor (GM-CSF) 10,000 units i.p. or locally s.c. daily for 4 days significantly enhanced protective antitumor immunity induced by s.c. Id-keyhole limpet hemocyanin (KLH) immunization. This effect was critically dependent upon effector CD4+ and CD8+ T cells and was not associated with any increased anti-idiotypic antibody production. Lymphocytes from spleens and draining lymph nodes of mice primed with Id-KLH plus GM-CSF, but not with Id-KLH alone, demonstrated significant proliferation to Id in vitro without any biased production of interferon gamma or interleukin 4 protein or mRNA. As a further demonstration of potency, 50% of mice immunized with Id-KLH plus GM-CSF on the same day as challenge with a large s.c. tumor inoculum remained tumor-free at day 80, compared with 17% for Id-KLH alone, when immunization was combined with cyclophosphamide. Taken together, these results demonstrate that GM-CSF can significantly enhance the immunogenicity of a defined self-antigen and that this effect is mediated exclusively by activating the T-cell arm of the immune response.

Tumor-specific, cytotoxic T-lymphocyte response after idiotype vaccination for B-cell, non-Hodgkin's lymphoma

Patients with non-Hodgkin's B-cell lymphoma who received an antitumor vaccine of idiotypic ig protein showed humoral and proliferative immune responses. Because immunity to some antigens, including tumor antigens and human pathogenic viruses, may be better correlated with the cytolytic cellular immune response, we evaluated 16 non-Hodgkin's lymphoma patients immunized with autologous idiotypic ig molecules for changes in tumor-specific cytotoxic T-lymphocyte precursor (CTLp) frequency using limiting dilution analysis. Eleven patients had a significant increase in tumor-specific CTLp. Eight of these 11 patients remain without evidence of disease or with stable minimal disease. In contrast, all five patients who did not have a significant change in tumor-specific CTLp have developed progressive disease. Patient vaccination with tumor associated protein antigens can increase tumor-specific CTLp frequencies. The correlation of increased tumor specific CTLp with freedom from progression is significant at P = .002. This study indicates that measurement of CTLp frequencies are relevant to the clinical evaluation of human tumor vaccines and suggests that cell-mediated cytolytic immune responses may be an important determinant of vaccine efficacy.

Immunization with granulocyte-macrophage colony-stimulating factor-transduced, but not B7-1-transduced, lymphoma cells primes idiotype-specific T cells and generates potent systemic antitumor immunity

Recently, genetically modified tumor cell vaccines have been described for nonhematopoietic cancers in which the relevant Ags are unknown. Several of these cell-based vaccine strategies have been shown to induce T cell-mediated systemic antitumor immunity, either by enhancing the processing and presentation of tumor Ags by host APCs or by facilitating effective Ag presentation by the tumor vaccine itself. These strategies were compared in a model B cell lymphoma, a tumor derived from APCs, which have the inherent capacity to activate Ag-specific T cells. Eradication of pre-established systemic lymphoma was achieved following immunization with lymphoma cells engineered to produce granulocyte-macrophage (GM)-CSF, and to a lesser extent cells producing IL-4, whereas vaccination with lymphoma cells transfected with the genes encoding IL-2 or B7-1 had no effect. The systemic immunity generated by GM-CSF- or IL-4-transfected lymphoma required both CD4+ and CD8+ T cells. Previous immunotherapeutic strategies for the treatment of lymphoma have focused on the generation of Ab responses targeted to the unique Ig Id as a tumor-specific Ag. Anti-idiotypic Abs were undetectable in animals vaccinated with GM-CSF-transduced lymphoma cells. In contrast, such immunization did result in the induction of Id-specific T cell responses. This is the first demonstration that T cell responses specific for a native tumor Ag are generated by GM-CSF-transduced tumor cell-based vaccination, suggesting that B cell lymphoma may be a suitable disease for genetically modified tumor vaccine strategies.

Immunization with granulocyte-macrophage colony-stimulating factor-transduced, but not B7-1-transduced, lymphoma cells primes idiotype-specific T cells and generates potent systemic antitumor immunity

Recently, genetically modified tumor cell vaccines have been described for nonhematopoietic cancers in which the relevant Ags are unknown. Several of these cell-based vaccine strategies have been shown to induce T cell-mediated systemic antitumor immunity, either by enhancing the processing and presentation of tumor Ags by host APCs or by facilitating effective Ag presentation by the tumor vaccine itself. These strategies were compared in a model B cell lymphoma, a tumor derived from APCs, which have the inherent capacity to activate Ag-specific T cells. Eradication of pre-established systemic lymphoma was achieved following immunization with lymphoma cells engineered to produce granulocyte-macrophage (GM)-CSF, and to a lesser extent cells producing IL-4, whereas vaccination with lymphoma cells transfected with the genes encoding IL-2 or B7-1 had no effect. The systemic immunity generated by GM-CSF- or IL-4-transfected lymphoma required both CD4+ and CD8+ T cells. Previous immunotherapeutic strategies for the treatment of lymphoma have focused on the generation of Ab responses targeted to the unique Ig Id as a tumor-specific Ag. Anti-idiotypic Abs were undetectable in animals vaccinated with GM-CSF-transduced lymphoma cells. In contrast, such immunization did result in the induction of Id-specific T cell responses. This is the first demonstration that T cell responses specific for a native tumor Ag are generated by GM-CSF-transduced tumor cell-based vaccination, suggesting that B cell lymphoma may be a suitable disease for genetically modified tumor vaccine strategies.

Active immunization of murine allogeneic bone marrow transplant donors with B-cell tumor-derived idiotype: a strategy for enhancing the specific antitumor effect of marrow grafts

Persistence of the underlying malignancy remains the major obstacle limiting the success of high-dose chemoradiotherapy with allogeneic bone marrow transplantation (BMT) for lymphomas and multiple myeloma. We used the C3H 38C13 murine B-cell lymphoma, which expresses and secretes clonally derived Ig, the idiotype of which can serve as a tumor-specific antigen, to test the principle of transfer of tumor idiotype-specific immunity with BM. BALB/c marrow donors were twice immunized with 38C13-derived Ig, or with an isotype-matched control Ig, conjugated to keyhole limpet hemocyanin. Lethally irradiated C3H recipients reconstituted with marrow from idiotype immune, but not nonspecifically immune, donors demonstrated protection against subsequent lethal tumor challenge. The immunoprotective effect of immune allogeneic marrow was abrogated by T-cell depletion of the marrow graft before infusion. Low levels of serum anti-idiotypic antibody remained unaltered in recipients of T-cell-depleted immune marrow, consistent with a primary role for T-cell immunity in the cellular mechanism of this phenomenon. A modest therapeutic effect of immune allogeneic marrow was observed against 10 day, 1 cm established subcutaneous tumors, but only in combination with a booster immunization of the recipient post-BMT. These results provide the rationale for a novel strategy for enhancing the specific antitumor effect of allogeneic marrow grafts.

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.

Transfer of myeloma idiotype-specific immunity from an actively immunised marrow donor

The idiotype of myeloma immunoglobulin can be used as a unique tumour-specific antigen. We tested the hypothesis that tumour antigen-specific immunity can be transferred from bone-marrow-transplant donor to recipient. We immunised a healthy sibling donor with myeloma immunoglobulin from the plasma of the recipient, conjugated to an immunogenic carrier protein and emulsified in an adjuvant, before marrow transplantation. Detection of a lymphoproliferative response, a parallel response in the carrier protein, recovery of a recipient CD4+ T-cell line with unique specificity for myeloma idiotype, and demonstration by in-situ hybridisation that the cell line was of donor origin, proved that a myeloma idiotype-specific T-cell response was successfully transferred to the recipient. Donor immunisation with myeloma idiotype may represent a new strategy for enhancing the specific anti-tumour effect of allogeneic marrow grafts.

Induction of a CD8+ cytotoxic T lymphocyte response to soluble antigen given together with a novel muramyl dipeptide adjuvant, N-acetyl-D-glucosaminyl-(beta 1-4)-N-acetylmuramyl-L-alanyl-D-isoglutamine (GMDP)

We have investigated the ability of the novel muramyl dipeptide, GMDP, to act as an adjuvant for the induction of ovalbumin (OVA)-specific, CD8+ cytotoxic T lymphocyte (CTL) responses. C57Bl/6 mice were twice immunized s.c. with 50 micrograms OVA emulsified with a squalane, L121 pluronic containing Tween-80 vehicle either with (STP-GMDP) or without (STP) GMDP. Splenic precursor CD8+ CTL activity against E.G7-OVA, but not against EL-4 parental targets was detected in STP-GMDP immunized mice after 5 days of in vitro re-stimulation with irradiated E.G7-OVA cells, while mice immunized with OVA in STP alone or OVA alone failed to demonstrate CTL activity. OVA emulsified in a microfluidized STP vehicle formulation without GMDP also elicited the E.G7-OVA precursor CTL. The ability of GMDP to induce a class I-restricted, CD8+ CTL response to a soluble protein antigen may have implications for the development of useful vaccines against viral pathogens or tumours against which CTL responses are desirable.

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.

MACOP-B +/- radiation therapy for diffuse large cell lymphoma. Analysis of the Stanford results according to prognostic indices

BACKGROUND

The efficacy and toxicity of the MA-COP-B regimen were assessed after outstanding results were reported in diffuse large cell lymphoma (DLCL) by the Vancouver group. The results are reported according to several proposed prognostic indices, including the recent International Prognostic Factors (IPF) Project.

METHODS

Forty-seven patients with untreated DLCL received MACOP-B chemotherapy. Thirty patients, most of whom had bulky disease, also received consolidative radiation therapy (RT). Patient characteristics include median age of 42 years, Stage III/IV (57%), bulky or symptomatic Stage II disease (43%), elevated lactic dehydrogenase (81%) and at least one extranodal site (72%).

RESULTS

At a median follow-up of 3.3 years, overall survival was 57% and freedom from progression (FFP) was 52%. The 3-year FFP data were related to tumor extent: 74% for limited stage versus 38% for extensive disease. These data correlated well with four prognostic indices reported in the literature. The IPF index accurately identified low-, intermediate-, and high-risk subgroups.

CONCLUSIONS

Patients with limited or low-risk DLCL have an excellent prognosis with MACOP-B +/- RT. These results do not support the use of consolidative high-dose therapy and bone marrow transplantation in patients with limited disease, even if bulky or accompanied by an elevated lactic dehydrogenase. Compared to historical CHOP data, MACOP-B +/- RT does not appear to improve outcome for those patients with poor prognostic features, most of whom will fail. The IPF index is a simple, accurate method of distinguishing high-risk patients who require new therapeutic initiatives.