Neoantigen and tumor antigen-specific immunity transferred from immunized donors is detectable early after allogeneic transplantation in myeloma patients.

To enhance the therapeutic index of allogeneic hematopoietic SCT (HSCT), we immunized 10 HLA-matched sibling donors before stem cell collection with recipient-derived clonal myeloma Ig, idiotype (Id), as a tumor antigen, conjugated with keyhole limpet hemocyanin (KLH). Vaccinations were safe in donors and recipients. Donor-derived KLH- and Id-specific humoral and central and effector memory T-cell responses were detectable by day 30 after HSCT and were boosted by post-transplant vaccinations at 3 months in most recipients. One patient died before booster vaccinations. Specifically, after completing treatment, 8/9 myeloma recipients had persistent Id-specific immune responses and 5/9 had improvement in disease status. Although regulatory T cells increased after vaccination, they did not impact immune responses. At a median potential follow-up period of 74 months, 6 patients are alive, the 10 patients have a median PFS of 28.5 months and median OS has not been reached. Our results provide proof of principle that neoantigen and tumor antigen-specific humoral and cellular immunity could be safely induced in HSCT donors and passively transferred to recipients. This general strategy may be used to reduce relapse of malignancies and augment protection against infections after allogeneic HSCT.

Conjugation of lymphoma idiotype to CD40 antibody enhances lymphoma vaccine immunogenicity and antitumor effects in mice.

Personalized immunotherapy of lymphoma based on tumor idiotype (Id) has shown anti-idiotype humoral immune responses in 40%-50% and cellular immune responses in 50%-75% of follicular lymphoma patients, indicating that this therapy can be clinically successful. We have developed a novel vaccine against lymphoma consisting of an anti-CD40 Ab (ADX40) chemically conjugated to the tumor idiotype A20 and tested it in a murine lymphoma model. BALB/c mice were immunized with 2 doses of immunogen alone or in conjunction with additional adjuvants before tumor challenge. ADX40-Id vaccination resulted in significantly retarded tumor growth and reduced mouse morbidity. Moreover, similar mouse survival was obtained with 2 injections of ADX40-Id as with 8 injections using the standard therapy of keyhole limpet hemocyanin Id + GM-CSF. Co-administration of ADX40-Id with 3-O-deacyl-4'-monophosphoryl lipid A further significantly enhanced vaccine efficacy, resulting in an increased overall survival. Anti-Id-specific Abs were detected at elevated levels after ADX40-Id immunization; however, in vivo depletion of CD4 and/or CD8 T cells before challenge showed that CD8 effector T cells were the major mediators of tumor protection. The results of the present study show that the ADX40-Id conjugate vaccine is a potential candidate as a stand-alone vaccine or in combination with currently licensed adjuvants for lymphoma immunotherapy.

CpG or IFN-α are more potent adjuvants than GM-CSF to promote anti-tumor immunity following idiotype vaccine in multiple myeloma.

Idiotype (Id) protein in combination with GM-CSF has been used as vaccines for immunotherapy of patients with myeloma and B-cell tumors and the results have been disappointing. To search for better immune adjuvants to improve the efficacy of Id-based immunotherapy in myeloma, we evaluated and compared the efficacy of vaccination of Id protein in combination with CpG or IFN-α, or GM-CSF as a control, in the 5TGM1 myeloma mouse model. Our results showed that Id vaccine combined with CpG or IFN-α, but not GM-CSF, not only efficiently protected mice from developing myeloma but also eradicated established myeloma. The therapeutic responses were associated with an induction of strong humoral immune responses including anti-Id antibodies, and cellular immune responses including Id- and myeloma-specific CD8+ cytotoxic T lymphocytes (CTLs), CD4+ type-1 T-helper (Th1) cells and memory T cells in mice receiving Id vaccine combined with CpG or IFN-α. Furthermore, Id vaccine combined with CpG or IFN-α induced Id- and tumor-specific memory immune responses that protected surviving mice from tumor rechallenge. Thus, our study clearly shows that CpG or IFN-α are better immune adjuvants than GM-CSF. This information will be important for improving the strategies of Id-based immunotherapy for patients with myeloma and other B-cell tumors.

BiovaxID®: a customized idiotype vaccine for the treatment of B-cell lymphoma.

Most patients with B-cell lymphoma face an often incurable disease, particularly those diagnosed with an indolent subtype. The addition of passive immunotherapy to old and new chemotherapy regimens has improved both response rates and disease-free survival, leading in many cases to an extended overall survival. However, a cure remains elusive in most cases. For this reason, the patient- and tumor-specific idiotype, that is the collection of epitopes exclusively presented by the tumor clone's surface immunoglobulin, has been extensively studied as a privileged target for vaccine therapy, aiming at preventing disease re-occurrence after standard treatment. BiovaxID(®) (Biovest International, FL, USA), the most clinically advanced among such therapeutic vaccines, finds itself at a crucial turning point when it comes to further development. Both clinical trials in which it has been formally employed have shown intriguing results. Independent studies using slightly different versions of a conceptually identical vaccine provided all proofs of principle required to ascertain the vaccine's value - biological and clinical efficacy as well as clinical benefit. However, all these data have failed to bring an idiotype vaccine to the market owing to reasons that often have very little to do with the product itself. In fact, some successful studies were not conceived with this goal in mind, while others simply did not enroll enough patients to convincingly make their case for regulatory approval. It is likely that one or more new clinical trials will have to be successfully completed to reach the ultimate goal - that is, to make BiovaxID available to most patients and to adequately position it in the very crowded therapeutic algorithm of B-cell lymphoma.

Anti-NeuGcGM3 antibodies, actively elicited by idiotypic vaccination in nonsmall cell lung cancer patients, induce tumor cell death by an oncosis-like mechanism.

1E10 is a murine anti-idiotypic mAb specific for an idiotypic mAb that reacts with NeuGc-containing gangliosides, sulfatides, and Ags expressed in some human tumors. In melanoma, breast, and lung cancer patients, this anti-idiotypic Ab was able to induce a specific Ab response against N-glycosylated gangliosides, attractive targets for cancer immunotherapy as these glycolipids are not naturally expressed in humans. A clinical study with nonsmall cell lung cancer patients showed encouraging clinical benefits. Immunological studies performed in 20 of these patients suggested a correlation between the induction of Abs against NeuGcGM3 and longer survival times. The induced anti-NeuGcGM3 Abs recognized and directly killed tumor cells expressing the Ag, by a mechanism independent of complement activation. In the present work, we show that this cytotoxicity differs from apoptosis because it is temperature independent, no chromatin condensation or caspase 3 induction are detected, and the DNA fragmentation induced has a different pattern than the one characteristic for apoptosis. It is a very quick process and involves cytosqeleton reorganization. The Abs induce cellular swelling and the formation of big membrane lesions that allow the leakage of cytoplasm and the loss of the cell membrane integrity. All of these characteristics resemble a process of oncotic necrosis. To our knowledge, this is the first report of the active induction in cancer patients of NeuGcGM3-specific Abs able to induce complement independent oncotic necrosis to tumor cells. These results contribute to reinforcing the therapeutic potential of anti-idiotypic vaccines and the importance of NeuGcGM3 ganglioside as antitumor target.

Idiotype-pulsed antigen-presenting cells following autologous transplantation for multiple myeloma may be associated with prolonged survival.

Vaccines are attractive as consolidation therapy after autologous stem cell transplantation (ASCT) for multiple myeloma (MM). We report the results of a phase II trial of the immunotherapeutic, APC8020 (Mylovenge), given after ASCT for MM. We compared the results with that of other patients with MM who underwent ASCT at Mayo Clinic during the same time period. Twenty-seven patients were enrolled on the trial between July, 1998 and June, 2001, and the outcomes were compared to that of 124 consecutive patients transplanted during the same period, but not enrolled on the trial. The median (range) follow-up for patients still alive from the vaccine trial is 6.5 (2.9-8 years), and 7.1 (6-8 years) in the control group. The median age was 57.4 range (36.1-71.3) in the DB group and 56.4 (range, 30-69) in the trial group. Known prognostic factors including PCLI, B2M, and CRP were comparable between the groups. The median overall survival for the trial patients was 5.3 years (95% CI: 4.0 years-N/A) compared to 3.4 years (95% CI: 2.7-4.6 years) for the DB group (P = 0.02). The median time to progression and progression-free survival for the trial group was similar to the DB group. Although not a controlled trial, the vaccines given after ASCT appear to be associated with improved overall survival compared to historical controls. This approach warrants further investigation to confirm this and define the role of vaccine therapy in myeloma.

Vaccine site inflammation potentiates idiotype DNA vaccine-induced therapeutic T cell-, and not B cell-, dependent antilymphoma immunity.

Lymphoma idiotype protein vaccines have shown therapeutic potential in previous clinical studies, and results from a completed pivotal, phase 3 controlled trial are promising. However, streamlined production of these patient-specific vaccines is required for eventual clinical application. Here, we show that second-generation, chemokine-fused idiotype DNA vaccines, when combined with myotoxins that induced sterile inflammation with recruitment of antigen-presenting cells at vaccination sites, were exceptional in their ability to provoke memory antitumor immunity in mice, compared with several TLR agonists. The combined vaccination strategy elicited both antigen-specific T-cell responses and humoral immunity. Unexpectedly, vaccine-induced tumor protection was intact in B cell-deficient mice but was abrogated completely by T-cell depletion in vivo, suggesting T-cell dependence. Furthermore, the optimal effect of myotoxins was observed with fusion vaccines that specifically targeted antigen delivery to antigen-presenting cells and not with vaccines lacking a targeting moiety, suggesting that the rational vaccine design will require combination strategies with novel, proinflammatory agents and highly optimized molecular vaccine constructs. These studies also challenge the paradigm that antibody responses are the primary of idiotype-specific antitumor effects and support the optimization of idiotype vaccines designed to induce primarily T-cell immunity.

Tumor-specific recombinant idiotype immunisation after chemotherapy as initial treatment for follicular non-Hodgkin lymphoma.

Tumor-specific variable regions of the clonal immunoglobulin (idiotype, Id) expressed by B cell non-Hodgkin lymphoma (NHL) can be targeted by active immunotherapy. We conducted a phase I/II trial to determine the safety and immunogenicity of a patient-specific, recombinant, mammalian cell-derived Id protein conjugated to keyhole limpet hemocyanin (Id-KLH; MyVax personalised immunotherapy) in 22 patients with follicular NHL in first remission after chemotherapy. Subjects received five subcutaneous immunisations with MyVax plus locally administered granulocyte-macrophage colony-stimulating factor (GM-CSF). Among 21 evaluable patients, 62% mounted Id-specific immune responses. Evoked anti-Id antibodies recognised both recombinant Id and native Id, and could specifically stain autologous tumor cells. At median follow-up of more than 6 years, median progression-free survival is 38 months. Immunisation of follicular lymphoma patients with MyVax Id-KLH is safe and patients often mount tumor-specific immune responses. These results form the basis of a pivotal phase 3 trial of MyVax in follicular NHL.

Sulfhydryl-based tumor antigen-carrier protein conjugates stimulate superior antitumor immunity against B cell lymphomas.

Therapeutic vaccination of B cell lymphoma patients with tumor-specific Ig (idiotype, or Id) chemically coupled to the immunogenic foreign carrier protein keyhole limpet hemocyanin (KLH) using glutaraldehyde has shown promising results in early clinical trials, and phase III trials are underway. However, glutaraldehyde Id-KLH vaccines fail to elicit anti-Id immune and clinical responses in many patients, possibly because glutaraldehyde reacts with lysine, cysteine, tyrosine, and histidine residues, damaging critical immunogenic epitopes. A sulfhydryl-based tumor Ag-carrier protein conjugation system using maleimide chemistry was used to enhance the efficacy of Id-KLH vaccines. Maleimide Id-KLH conjugates eradicated A20 lymphoma from most tumor-bearing mice, whereas glutaraldehyde Id-KLH had little efficacy. Maleimide Id-KLH elicited tumor-specific IgG Abs and T cells, with CD8(+) T cells being the major effectors of antilymphoma immunity. Maleimide Id-KLH vaccines also demonstrated superior efficacy in 38C13 and BCL-1 lymphoma models, where Abs were shown to be critical for protection. Importantly, standard glutaraldehyde Id-KLH conjugation procedures could result in "overconjugation" of the tumor Ag, leading to decreased efficacy, whereas the heterobifunctional maleimide-based conjugation yielded potent vaccine product regardless of conjugation duration. Under lysosomal processing conditions, the Id-carrier protein linkage was cleavable only after maleimide conjugation. Maleimide KLH conjugation was easily performed with human Igs analogous to those used in Id-KLH clinical trials. These data support the evaluation of sulfhydryl-based Id-KLH vaccines in lymphoma clinical trials and possibly the use of tumor Ag-carrier protein vaccines for other cancers.

Boosting anti-idiotype immune response with recombinant AAV enhances tumour protection induced by gene gun vaccination.

Thanks to the safety of administration, efficiency of in vivo transduction and persistence of transgene expression, vectors based on the adeno-associated virus (AAV) are extensively utilized in both preclinical and clinical experimentation. Here we thoroughly explore the potential of AAV-mediated antigen delivery for tumour vaccination. A recombinant AAV vector (rAAV) encoding a lymphoma idiotype (Id) in a single-chain variable fragment format was found to induce an efficient anti-Id immune response upon injection in immunocompetent animals. The intensity of the immune response and the protective effect of rAAV administration in vivo were systematically compared with those elicited by simple injection of naked DNA or biolistic immunization. The results indicate that Id delivery via rAAV enhances the intensity of immune response compared with injection of naked DNA, while anti-idiotypic antibodies titres are not considerably increased compared with biolistic vaccination. On the contrary, a prime-boost vaccination strategy combining biolistic and AAV DNA delivery results in a major increase in anti-Id antibody response compared with the repetitive biolistic immunization. This increased anti-Id humoral response strictly correlated with a significant improvement on tumour protection in vivo.

Long-term effects of idiotype vaccination on the specific T-cell response in peripheral blood and bone marrow of multiple myeloma patients.

OBJECTIVES: To elucidate long-term effects of idiotype (Id) vaccination on Id-specific T cells of multiple myeloma (MM) patients and compare Id-specific T-cell responses of peripheral blood with those of bone marrow (BM). MATERIALS AND METHODS: Id-specific T-cell responses of peripheral blood mononuclear cells (PBMC) were compared with those of BM mononuclear cells (BMMC) in 10 MM patients vaccinated with the Id protein at a median time of 41 months since the last immunization. The PBMC responses at late follow-up were also compared with those during active immunization. The responses were assessed by a proliferation assay, enzyme-linked immunospot (ELISPOT) (gamma-interferon), cytometric bead array (CBA) for secreted cytokines and quantitative real-time polymerase chain reaction (QRT-PCR) for cytokine gene expression. RESULTS: At the late testing time, an Id-specific response was detected in PBMC of five patients (ELISPOT, CBA, QRT-PCR) and in BMMC of four patients (CBA, QRT-PCR). A response in both compartments was noted only in three patients. The cytokines gene profile was consistent with a predominance of Th(2) cells [interleukin (IL)-4, IL-5, IL-10]. Comparison of the Id-specific responses of PBMC during active immunization with those at the late follow-up showed that the frequency and magnitude of the responses had decreased significantly by time (proliferation/ELISPOT) (P < 0.02) and shifted at the gene level from a Th(1) to a Th(2) profile (P < 0.05). CONCLUSION: Id-specific T-cells may decline overtime and shift toward a Th(2) response and may be found at a similar frequency of patients in blood and BM.

[Induction of active antitumor immune response by myeloma idiotype protein-pulsed dendritic cells].

BACKGROUND & OBJECTIVE: Most multiple myeloma (MM) patients could not be cured by high-dose chemotherapy and bone marrow transplantation. This study was designed to investigate in vitro killing effect of tumor-specific cytotoxic T lymphocytes (CTLs) stimulated by idiotype protein (Id)-pulsed dendritic cells (DCs) on autologous MM cells. METHODS: DCs were generated from peripheral blood monocytes of 6 MM patients using interleukin-4 (IL-4) and granulocyte-macrophage colony-stimulating factor (GM-CSF). After cultured for 5 days, immature DCs were pulsed with Idû tumor necrosis factor-alpha (TNF-alpha) was added at the 7th day. Id-pulsed DCs were cocultured with autologous T cells for 3 days to induce tumor-specific CTLs. MTT assay was used to detect proliferation of autologous T cells, and evaluate killing effect of CTLs on autologous MM cells. RESULTS: Mature DCs were successfully induced. Id-pulsed DCs markedly increased proliferation of autologous T cells in a dose-dependent manner; stimulation index (SI) of Id-pulsed DCs was the highest [(39.1+/-6.0)%] when the radio of DCs to T cells was 10:1, which was significantly higher than those of unpulsed mature DCs [(19.3+/-7.7)%], Id-pulsed immature DCs [(15.9+/-6.1)%], and unpulsed immature DCs [(11.4+/-4.9)%] (P < 0.01). Id-pulsed DCs induced anti-MM activity of CTLs in a dose-dependent manner. Unpulsed mature DCs also induced cytotoxicity of CTLs against autologous MM cellsû however, when DC:T was 30:1, killing rate of MM cells was significantly higher in Id-pulsed mature DCs group than in unpulsed mature DCs group [(70.1+/-7.9)% vs. (40.8+/-7.8)%,P < 0.05]. KRN7000-pulsed mature DCs stimulated proliferation of allogeneic T cells in a dose-dependent manner; when DC:T was 1:10, SI was significantly higher in KRN7000-pulsed mature DCs group than in unpulsed mature DCs group [(38.5+/-5.7)% vs. (20.2+/-5.7)%, P < 0.05]. CONCLUSIONS: Mature DCs could be induced and Id with biological activity could be extracted from peripheral blood of MM patients. Id-pulsed DCs could induce antitumor immune response. KRN7000 could improve the immune function of in vitro cultured DCs.

Therapeutic effects of idiotype vaccination can be enhanced by the combination of granulocyte-macrophage colony-stimulating factor and interleukin 2 in a myeloma model.

Idiotype (Id) vaccination provides an interesting immunotherapeutic strategy against B-cell lymphomas. In multiple myeloma (MM), however, the therapeutic efficacy of Id vaccination has been disappointing. In an attempt to improve the antitumoral potential, we added granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin 2 (IL-2) to the protocol. Balb/c mice were inoculated i.p. (d 2) with different doses (1-5 x 10(5)) of HOPC myeloma cells secreting the Ig(HOPC) Id protein. Two days later, animals were injected with 10,000 U GM-CSF i.p. for 6 d consecutively (d 0-5). On d 5 and 11, myeloma-specific immunoglobulin (Ig(HOPC)) was administered i.p. together with incomplete Freund adjuvans followed by IL-2 (2 x 10,000 U/d; i.p) for 10 d (d 5-14). In animals inoculated with 10(5) myeloma cells, treatment with IL-2 given as a single agent prolonged the median survival time (MST, 67 d) when compared with the tumour control group (MST 48 d), whereas GM-CSF did not elicit any survival benefit (MST 49 d). Complete tumour rejection could be achieved in 27% (4/15) by the combination of Id vaccination and GM-CSF. Additional treatment with IL-2 further increased antimyeloma activity. In this case, 59% of the animals showed no signs of tumour recurrence. In mice with high tumour burden (5 x 10(5)), no treatment modality achieved long-term survivors. Both natural killer (NK) cells and CD8+ T cells may be involved in the anti-tumoural immune response. These data provide evidence for the combined use of GM-CSF and IL-2 to enhance the therapeutic effectiveness of clinical cancer vaccination protocols.

Tumor cell lysate-pulsed dendritic cells are more effective than TCR Id protein vaccines for active immunotherapy of T cell lymphoma.

TCR Id protein conjugated to keyhole limpet hemocyanin (KLH) (TCR Id:KLH) and injected with a chemical adjuvant (QS-21) induces a protective, Id-specific immune response against the murine T cell lymphoma, C6VL. However, Id-based immunotherapy of C6VL has not demonstrated therapeutic efficacy in tumor-bearing mice. We report here that C6VL lysate-pulsed dendritic cells (C6VL-DC) vaccines display enhanced efficacy in both the prevention and the therapy of T cell lymphoma compared with TCR Id:KLH with QS-21 vaccines. C6VL-DC vaccines stimulated potent tumor-specific immunity that protected mice against lethal challenge with C6VL and significantly enhanced the survival of tumor-bearing mice. Tumor-specific proliferation and secretion of IFN-gamma indicative of a Th1-type immune response were observed upon ex vivo stimulation of vaccine-primed lymph node cells. Adoptive transfer of immune T cell-enriched lymphocytes was sufficient to protect naive recipients from lethal tumor challenge. Furthermore, CD8(+) T cells were absolutely required for tumor protection. Although C6VL-DC and control vaccines stimulated low levels of tumor-specific Ab production in mice, Ab levels did not correlate with the protective ability of the vaccine. Thus, tumor cell lysate-pulsed DC vaccines appear to be an effective approach to generate potent T cell-mediated immune responses against T cell malignancies without requiring identification of tumor-specific Ags or patient-specific Id protein expression.

Immunization with a recombinant adenovirus encoding a lymphoma idiotype: induction of tumor-protective immunity and identification of an idiotype-specific T cell epitope.

The Ig Id of a B cell lymphoma is a tumor-specific Ag, although as a self-Ag it is likely to be a weak immunogen. Provision of a foreign gene may enhance the immunogenicity of the idiotype. Viral vectors allow highly efficient transfer of genetic material and are themselves innately immunogenic. We have investigated the ability of recombinant adenoviral vectors, encoding the idiotypic gene with or without fusion to the human Fc region, to produce anti-idiotypic Ab- and T cell-mediated responses in a syngeneic BALB/c A20 murine lymphoma model. The idiotypic V(H) and V(L) sequences were assembled as a single chain variable fragment (scFv) and adenoviral vectors encoding the A20 scFv (Ad.A20) and A20 scFv linked to the Fc fragment of human IgG1 (Ad.A20hFc) were constructed. A single immunization of BALB/c mice with Ad.A20hFc but not Ad.A20 induced a specific anti-idiotypic Ab response. T cell lines generated from mice vaccinated with either vector displayed specific cytotoxicity, proliferation, and IFN-gamma release against a syngeneic dendritic cell line transduced using a retroviral vector to express the A20 scFv idiotype (XS52.A1.A20). Importantly, both T cell lines lysed the A20 lymphoma cells. An immunodominant H-2K(d)-restricted CD8(+) T cell peptide, DYWGQGTEL (A20[106-114]), was identified as a naturally occurring A20 scFv epitope. A single immunization with Ad.A20hFc but not Ad.A20 provided protection in >40% of animals challenged with a lethal dose of the A20 tumor line and was more effective, in this model, than a previously optimized plasmid vaccine.

Enhanced antitumoral effectiveness of idiotype vaccination induced by the administration of Flt3 ligand combined with interleukin 2 against a murine myeloma.

Idiotype (Id) vaccination provides an innovative treatment modality against B-cell malignancies. In multiple myeloma patients, however, the antitumoral potential of this immunotherapeutic concept is limited. In an attempt to improve the therapeutic effectiveness of Id vaccination, we added Flt3 ligand (Flt3-L) and interleukin 2 (IL-2) to the protocol. Balb/c mice were inoculated i.p. (d -2) with different doses (1-5 x 10(5)) of HOPC myeloma cells, secreting the IgHOPC Id-protein. Two days later, animals were treated with Flt3-L (10 microg per mouse/d, given i.p) for 10 consecutive days (d 0-9). On d 5 and d 11, myeloma-specific immunoglobulin (Ig(HOPC)) was administered s.c., together with incomplete Freund adjuvans (IFA) followed by the administration of IL-2 (2 x 10.000/d given i.p) for 10 d (d 5-14). Whereas Ig(HOPC), Flt3-L or IL-2, given alone, did not elicit long-term survival, the combination of IL-2 or Flt3-L with Id vaccination achieved a complete tumour rejection in 27% and 41% of mice respectively. However, the most powerful antimyeloma effects were induced by Flt3-L + Id vaccination + IL-2: 81% of the treated animals experienced long-term survival (> 180 d). Both natural killer (NK) cells and CD8+ T cells may be involved in the antitumoral immune response. These data suggest that the combination of Flt3-L and IL-2 can be used to enhance the therapeutic effectiveness of clinical cancer vaccination protocols.

Idiotype vaccination following ABMT can stimulate specific anti-idiotype immune responses in patients with B-cell lymphoma.

Vaccination with the idiotype (Id) protein derived from B-cell malignancies can produce Id-specific immune responses that correlate with improved remission duration and survival rates in patients with follicular non-Hodgkin's lymphoma (NHL). A state of minimal or no residual disease correlates strongly with the laboratory detection of a cellular or humoral immune response. High-dose cytotoxic therapy (HDCT) with autologous stem cell support (autologous bone marrow transplantation [ABMT]) can provide profound cytoreduction of B-cell NHL, but the potential immune suppression associated with myeloablative therapy may compromise a patient's ability to mount a specific immune response. To determine whether patients with NHL could mount detectable immuneresponses following ABMT, Id vaccines were administered at 2 to 12 months following myeloablative therapy to a series of patients with relapsed or resistant B-cell NHL. Two different vaccination strategies produced robust immune responses against KLH in all patients, supporting the capacity of the reconstituted immune system following HDCT to react against a strong antigen. Combining the results from both vaccination strategies, 10 of 12 patients mounted Id-specific humoral or cellular responses. Vaccinations were consistently well tolerated. Of the 12 patients, 7 have experienced prolonged remissions with a follow-up from HDCT ranging from 3 to more than 11 years. Our experience serves to document the ability of the recovering immune system to react against both self and xenotypic antigens and supports the feasibility and safety of antigen-specific vaccination following myeloablative therapy in patients with B-cell NHL.

Antitumor effect of the idiotypic cascade induced by an antibody encapsulated in poly(d,l-lactide-co-glycolide) microspheres.

A major difficulty encountered during development of antibody vaccines is their weak immunogenicity. In this study, a monoclonal antibody CS20.5 to human breast cancer antigen CA15.3 was coencapsulated in poly(d,l-lactide-co-glycolide) microspheres with monophosphoryl lipid A. The antitumor effect of this formulation was investigated in a murine model. The induced Ab2 biologically mimics antigen as it competed with CA15.3 for the same idiotope on Ab1. Ab3 induction was also observed. After five sequential administrations of encapsulated antibody, mice showed statistically significant tumor regression. These results indicate that this formulation may serve as a potential treatment for breast cancer.

Idiotype vaccination using dendritic cells after autologous peripheral blood progenitor cell transplantation for multiple myeloma.

The idiotype (Id) determinants on the multiple myeloma immunoglobulin can serve as tumor-specific antigens. An anti-Id immune response may stem the growth of the malignant clone. We report on 26 patients treated at our institution with high-dose chemotherapy and peripheral blood progenitor cell transplantation (PBPCT) and vaccinated with the Id protein. The patients received chemotherapy and PBPCT to establish a minimal residual disease state. After high-dose therapy, the patients received a series of monthly immunizations consisting of 2 intravenous infusions of dendritic cells (DCs) pulsed with either Id protein or Id coupled with keyhole limpet hemocyanin (KLH) as an immunogenic carrier protein, followed by subcutaneous boosts of Id-KLH conjugates. DCs were obtained in all patients from a leukapheresis product 3 to 9 months after PBPCT. Patients were observed for toxicity, immune responses, and tumor status. The DC infusions and the administration of Id-KLH boosts were well tolerated, with patients experiencing only minor and transient side effects. Of the patients, 24 of 26 generated a KLH-specific cellular proliferative immune response. Only 4 patients developed an Id-specific proliferative immune response. Three of these immune responders were in complete remission at the time of vaccination. A total of 17 patients are alive at a median follow-up of 30 months after transplantation. Id vaccination with autologous DCs is feasible for myeloma patients after transplantation. Id-specific cellular responses can be induced in patients who are in complete remission. Further studies are needed to increase the rate of anti-Id immune responses in patients who do not achieve complete remission.