Combination of mAb-AR20.5, anti-PD-L1 and PolyICLC inhibits tumor progression and prolongs survival of MUC1.Tg mice challenged with pancreatic tumors.

A substantial body of evidence suggests the existence of MUC1-specific antibodies and cytotoxic T cell activities in pancreatic cancer patients. However, tumor-induced immunosuppression renders these responses ineffective. The current study explores a novel therapeutic combination wherein tumor-bearing hosts can be immunologically primed with their own antigen, through opsonization with a tumor antigen-targeted antibody, mAb-AR20.5. We evaluated the efficacy of immunization with this antibody in combination with PolyICLC and anti-PD-L1. The therapeutic combination of mAb-AR20.5 + anti-PD-L1 + PolyICLC induced rejection of human MUC1 expressing tumors and provided a long-lasting, MUC1-specific cellular immune response, which could be adoptively transferred and shown to provide protection against tumor challenge in human MUC1 transgenic (MUC.Tg) mice. Furthermore, antibody depletion studies revealed that CD8 cells were effectors for the MUC1-specific immune response generated by the mAb-AR20.5 + anti-PD-L1 + PolyICLC combination. Multichromatic flow cytometry data analysis demonstrated a significant increase over time in circulating, activated CD8 T cells, CD3+CD4-CD8-(DN) T cells, and mature dendritic cells in mAb-AR20.5 + anti-PD-L1 + PolyICLC combination-treated, tumor-bearing mice, as compared to saline-treated control counterparts. Our study provides a proof of principle that an effective and long-lasting anti-tumor cellular immunity can be achieved in pancreatic tumor-bearing hosts against their own antigen (MUC1), which can be further potentiated using a vaccine adjuvant and an immune checkpoint inhibitor.

Controlled tetra-Fc sialylation of IVIg results in a drug candidate with consistent enhanced anti-inflammatory activity.

Despite the beneficial therapeutic effects of intravenous immunoglobulin (IVIg) in inflammatory diseases, consistent therapeutic efficacy and potency remain major limitations for patients and physicians using IVIg. These limitations have stimulated a desire to generate therapeutic alternatives that could leverage the broad mechanisms of action of IVIg while improving therapeutic consistency and potency. The identification of the important anti-inflammatory role of fragment crystallizable domain (Fc) sialylation has presented an opportunity to develop more potent Ig therapies. However, translating this concept to potent anti-inflammatory therapeutics has been hampered by the difficulty of generating suitable sialylated products for clinical use. Therefore, we set out to develop the first, to our knowledge, robust and scalable process for generating a well-qualified sialylated IVIg drug candidate with maximum Fc sialylation devoid of unwanted alterations to the IVIg mixture. Here, we describe a controlled enzymatic, scalable process to produce a tetra-Fc-sialylated (s4-IVIg) IVIg drug candidate and its qualification across a wide panel of analytic assays, including physicochemical, pharmacokinetic, biodistribution, and in vivo animal models of inflammation. Our in vivo characterization of this drug candidate revealed consistent, enhanced anti-inflammatory activity up to 10-fold higher than IVIg across different animal models. To our knowledge, this candidate represents the first s4-IVIg suitable for clinical use; it is also a valuable therapeutic alternative with more consistent and potent anti-inflammatory activity.

A novel IgE antibody targeting the prostate-specific antigen as a potential prostate cancer therapy.

BACKGROUND: Prostate cancer (PCa) is the second leading cause of cancer deaths in men in the United States. The prostate-specific antigen (PSA), often found at high levels in the serum of PCa patients, has been used as a marker for PCa detection and as a target of immunotherapy. The murine IgG1 monoclonal antibody AR47.47, specific for human PSA, has been shown to enhance antigen presentation by human dendritic cells and induce both CD4 and CD8 T-cell activation when complexed with PSA. In this study, we explored the properties of a novel mouse/human chimeric anti-PSA IgE containing the variable regions of AR47.47 as a potential therapy for PCa. Our goal was to take advantage of the unique properties of IgE in order to trigger immune activation against PCa. METHODS: Binding characteristics of the antibody were determined by ELISA and flow cytometry. In vitro degranulation was determined by the release of ß-hexosaminidase from effector cells. In vivo degranulation was monitored in human FcεRIα transgenic mice using the passive cutaneous anaphylaxis assay. These mice were also used for a vaccination study to determine the in vivo anti-cancer effects of this antibody. Significant differences in survival were determined using the Log Rank test. In vitro T-cell activation was studied using human dendritic cells and autologous T cells. RESULTS: The anti-PSA IgE, expressed in murine myeloma cells, is properly assembled and secreted, and binds the antigen and FcεRI. In addition, this antibody is capable of triggering effector cell degranulation in vitro and in vivo when artificially cross-linked, but not in the presence of the natural soluble antigen, suggesting that such an interaction will not trigger systemic anaphylaxis. Importantly, the anti-PSA IgE combined with PSA also triggers immune activation in vitro and in vivo and significantly prolongs the survival of human FcεRIα transgenic mice challenged with PSA-expressing tumors in a prophylactic vaccination setting. CONCLUSIONS: The anti-PSA IgE exhibits the expected biological properties and is capable of triggering immune activation and anti-tumor protection. Further studies on this antibody as a potential PCa therapy are warranted.

Epithelial ovarian cancer is infiltrated by activated effector T cells co-expressing CD39, PD-1, TIM-3, CD137 and interacting with cancer cells and myeloid cells.

Introduction: Despite predicted efficacy, immunotherapy in epithelial ovarian cancer (EOC) has limited clinical benefit and the prognosis of patients remains poor. There is thus a strong need for better identifying local immune dynamics and immune-suppressive pathways limiting T-cell mediated anti-tumor immunity. Methods: In this observational study we analyzed by immunohistochemistry, gene expression profiling and flow cytometry the antigenic landscape and immune composition of 48 EOC specimens, with a focus on tumor-infiltrating lymphocytes (TILs). Results: Activated T cells showing features of partial exhaustion with a CD137+CD39+PD-1+TIM-3+CD45RA-CD62L-CD95+ surface profile were exclusively present in EOC specimens but not in corresponding peripheral blood or ascitic fluid, indicating that the tumor microenvironment might sustain this peculiar phenotype. Interestingly, while neoplastic cells expressed several tumor-associated antigens possibly able to stimulate tumor-specific TILs, macrophages provided both co-stimulatory and inhibitory signals and were more abundant in TILs-enriched specimens harboring the CD137+CD39+PD-1+TIM-3+CD45RA-CD62L-CD95+ signature. Conclusion: These data demonstrate that EOC is enriched in CD137+CD39+PD-1+TIM-3+CD45RA-CD62L-CD95+ T lymphocytes, a phenotype possibly modulated by antigen recognition on neoplastic cells and by a combination of inhibitory and co-stimulatory signals largely provided by infiltrating myeloid cells. Furthermore, we have identified immunosuppressive pathways potentially hampering local immunity which might be targeted by immunotherapeutic approaches.

Targeting HER2/neu with a fully human IgE to harness the allergic reaction against cancer cells.

Breast and ovarian cancer are two of the leading causes of cancer deaths among women in the United States. Overexpression of the HER2/neu oncoprotein has been reported in patients affected with breast and ovarian cancers, and is associated with poor prognosis. To develop a novel targeted therapy for HER2/neu expressing tumors, we have constructed a fully human IgE with the variable regions of the scFv C6MH3-B1 specific for HER2/neu. This antibody was expressed in murine myeloma cells and was properly assembled and secreted. The Fc region of this antibody triggers in vitro degranulation of rat basophilic cells expressing human FcεRI (RBL SX-38) in the presence of murine mammary carcinoma cells that express human HER2/neu (D2F2/E2), but not the shed (soluble) antigen (ECD(HER2)) alone. This IgE is also capable of inducing passive cutaneous anaphylaxis in a human FcεRIα transgenic mouse model, in the presence of a cross-linking antibody, but not in the presence of soluble ECD(HER2). Additionally, IgE enhances antigen presentation in human dendritic cells and facilitates cross-priming, suggesting that the antibody is able to stimulate a secondary T-cell anti-tumor response. Furthermore, we show that this IgE significantly prolongs survival of human FcεRIα transgenic mice bearing D2F2/E2 tumors. We also report that the anti-HER2/neu IgE is well tolerated in a preliminary study conducted in Macaca fascicularis (cynomolgus) monkeys. In summary, our results suggest that this IgE should be further explored as a potential therapeutic against HER2/neu overexpressing tumors, such as breast and ovarian cancers.

CRISPR-based gene disruption and integration of high-avidity, WT1-specific T cell receptors improve antitumor T cell function.

T cell receptor (TCR)-based therapy has the potential to induce durable clinical responses in patients with cancer by targeting intracellular tumor antigens with high sensitivity and by promoting T cell survival. However, the need for TCRs specific for shared oncogenic antigens and the need for manufacturing protocols able to redirect T cell specificity while preserving T cell fitness remain limiting factors. By longitudinal monitoring of T cell functionality and dynamics in 15 healthy donors, we isolated 19 TCRs specific for Wilms' tumor antigen 1 (WT1), which is overexpressed by several tumor types. TCRs recognized several peptides restricted by common human leukocyte antigen (HLA) alleles and displayed a wide range of functional avidities. We selected five high-avidity HLA-A*02:01-restricted TCRs, three that were specific to the less explored immunodominant WT137-45 and two that were specific to the noncanonical WT1-78-64 epitopes, both naturally processed by primary acute myeloid leukemia (AML) blasts. With CRISPR-Cas9 genome editing tools, we combined TCR-targeted integration into the TCR α constant (TRAC) locus with TCR ß constant (TRBC) knockout, thus avoiding TCRαß mispairing and maximizing TCR expression and function. The engineered lymphocytes were enriched in memory stem T cells. A unique WT137-45-specific TCR showed antigen-specific responses and efficiently killed AML blasts, acute lymphoblastic leukemia blasts, and glioblastoma cells in vitro and in vivo in the absence of off-tumor toxicity. T cells engineered to express this receptor are being advanced into clinical development for AML immunotherapy and represent a candidate therapy for other WT1-expressing tumors.

Necuparanib, A Multitargeting Heparan Sulfate Mimetic, Targets Tumor and Stromal Compartments in Pancreatic Cancer.

Pancreatic cancer has an abysmal 5-year survival rate of 8%, making it a deadly disease with a need for novel therapies. Here we describe a multitargeting heparin-based mimetic, necuparanib, and its antitumor activity in both in vitro and in vivo models of pancreatic cancer. Necuparanib reduced tumor cell proliferation and invasion in a three-dimensional (3D) culture model; in vivo, it extended survival and reduced metastasis. Furthermore, proteomic analysis demonstrated that necuparanib altered the expression levels of multiple proteins involved in cancer-driving pathways including organ development, angiogenesis, proliferation, genomic stability, cellular energetics, and invasion and metastasis. One protein family known to be involved in invasion and metastasis and altered by necuparanib treatment was the matrix metalloprotease (MMP) family. Necuparanib reduced metalloproteinase 1 (MMP1) and increased tissue inhibitor of metalloproteinase 3 (TIMP3) protein levels and was found to increase RNA expression of TIMP3. MMP enzymatic activity was also found to be reduced in the 3D model. Finally, we confirmed necuparanib's in vivo activity by analyzing plasma samples of patients enrolled in a phase I/II study in patients with metastatic pancreatic cancer; treatment with necuparanib plus standard of care significantly increased TIMP3 plasma protein levels. Together, these results demonstrate necuparanib acts as a broad multitargeting therapeutic with in vitro and in vivo anti-invasive and antimetastatic activity.

Elucidating the interplay between IgG-Fc valency and FcγR activation for the design of immune complex inhibitors.

Autoantibody immune complex (IC) activation of Fcγ receptors (FcγRs) is a common pathogenic hallmark of multiple autoimmune diseases. Given that the IC structural features that elicit FcγR activation are poorly understood and the FcγR system is highly complex, few therapeutics can directly block these processes without inadvertently activating the FcγR system. To address these issues, the structure activity relationships of an engineered panel of multivalent Fc constructs were evaluated using sensitive FcγR binding and signaling cellular assays. These studies identified an Fc valency with avid binding to FcγRs but without activation of immune cell effector functions. These observations directed the design of a potent trivalent immunoglobulin G-Fc molecule that broadly inhibited IC-driven processes in a variety of immune cells expressing FcγRs. The Fc trimer, Fc3Y, was highly efficacious in three different animal models of autoimmune diseases. This recombinant molecule may represent an effective therapeutic candidate for FcγR-mediated autoimmune diseases.

Randomized, placebo-controlled study of oregovomab for consolidation of clinical remission in patients with advanced ovarian cancer.

PURPOSE: To assess oregovomab as consolidation treatment of advanced ovarian cancer and refine the immunotherapeutic strategy for subsequent study. PATIENTS AND METHODS: Patients with stage III/IV ovarian cancer who had a complete clinical response to primary treatment were randomly assigned to oregovomab or placebo administered at weeks 0, 4, and 8, and every 12 weeks up to 2 years or until recurrence. The primary end-point was time to relapse (TTR). RESULTS: One hundred forty-five patients were treated with oregovomab (n = 73) or placebo (n = 72). For the population overall, median TTR was not different between treatments at 13.3 months for oregovomab and 10.3 months for placebo (P =.71). Immune responses were induced in most actively treated patients. This was associated with prolonged TTR. Quality of life was not adversely impacted by treatment. Adverse events were reported with similar frequency in oregovomab and placebo groups, indicating a benign safety profile. A long-term survival follow-up is ongoing. Cox analysis of relapse data identified significant factors: performance status, CA-125 before third cycle, and baseline CA-125. Further evaluation identified a subpopulation with favorable prognostic indicators designated as the successful front-line therapy (SFLT) population. For the SFLT population, TTR was 24.0 months in the oregovomab group compared with 10.8 months for placebo (unadjusted hazard ratio of 0.543 [95% CI, 0.287 to 1.025]), a hypothesis-generating observation. CONCLUSION: Consolidation therapy with oregovomab did not significantly improve TTR overall. A set of confirmatory phase III studies has been initiated to determine whether the SFLT population derives benefit from oregovomab treatment.

Monitoring of immune responses to CA125 with an IFN-gamma ELISPOT assay.

The CA125 (carcinoma antigen 125)-specific antibody MAb-B43.13 (OvaRex MAb-B43.13) is in clinical trials for patients with ovarian carcinoma as an immunotherapeutic agent. To develop an assay for monitoring CA125-specific as well as tumor-specific T cells in the peripheral circulation of ovarian cancer patients treated with this antibody, the IFN (interferon)-gamma enzyme-linked immuno SPOT (ELISPOT) assay was optimized. Various assay formats and experimental conditions were evaluated, using peripheral blood mononuclear cells (PBMC) obtained from normal donors and patients with ovarian cancer. T cell proliferation assays were performed in parallel. Conditions tested included different types of antigen presenting cells (APC), the need for and length of in vitro sensitization to enrich in T cell precursors, titration of the antigen and comparison of pulsing dendritic cells (DC) with immune complexes (IC) of CA125 and monoclonal antibody (MAb)-B43.13 or CA125 antigen alone. Proliferation assays were found not to be sufficiently sensitive for detection of CA125-specific T cells in the peripheral circulation of normal donors. A more sensitive 24-h direct ELISPOT assay was also negative. However, ELISPOT assays preceded by a 7-day in vitro sensitization (IVS) step allowed the detection of CA125 antigen-specific T cells in the circulation of normal donors and patients with ovarian cancer. The use of DC as APC was compared to whole PBMC or immortalized B cells. Most donors and ovarian cancer patients responded best to DC pulsed with CA125 in the form of immune complexes. Optimal responses were seen using CA125 concentrations of 500 U/ml and 5 microg/ml of MAb-B43.13. The data indicate that precursor cells specific for CA125 antigen are present at low frequencies in the peripheral circulation of normal donors and patients with ovarian carcinoma and need to be expanded ex vivo for frequency determinations. The optimized assay is able to detect increases in T cell precursor frequencies to CA125 in ovarian cancer patients after immunization with MAb-B43.13.

Immunomodulation with antibodies: clinical application in ovarian cancer and other malignancies.

This review identifies the role of antibodies in the field of therapeutic cancer vaccines. Ovarian cancer is used as a model to review advances in therapeutic vaccine development with a focus on antibodies as immunomodulators and antigen mimetics, highlighting research on B43.13 and ACA125. The interaction of biological immunomodulation and chemotherapy is discussed. Requirements of antigen processing and recent advances in the field of dendritic cell biology are critical to current understanding of potent immune response induction. Future directions including use of growth factors, adjuvants and cellular therapies to enhance effects may potentiate observed effects and provide clues for application in many cancers and beyond oncology.

Synthesis and biological evaluation of a unique heparin mimetic hexasaccharide for structure-activity relationship studies.

To date, the structure-activity relationship studies of heparin/heparan sulfate with their diverse binding partners such as growth factors, cytokines, chemokines, and extracellular matrix proteins have been limited yet provide early insight that specific sequences contribute to this manifold biological role. This has led to an impetus for the chemical synthesis of oligosaccharide fragments of these complex polysaccharides, which can provide an effective tool for this goal. The synthesis of three heparin mimetic hexasaccharides with distinct structural patterns is described herein, and the influence of the targeted substitution on their bioactivity profiles is studied using in vitro affinity and/or inhibition toward different growth factors and proteins. Additionally, the particularly challenging synthesis of an irregular hexasaccharide is reported, which, interestingly, in spite of being considerably structurally similar with its two counterparts, displayed a unique and remarkably distinct profile in the test assays.

M402, a novel heparan sulfate mimetic, targets multiple pathways implicated in tumor progression and metastasis.

Heparan sulfate proteoglycans (HSPGs) play a key role in shaping the tumor microenvironment by presenting growth factors, cytokines, and other soluble factors that are critical for host cell recruitment and activation, as well as promoting tumor progression, metastasis, and survival. M402 is a rationally engineered, non-cytotoxic heparan sulfate (HS) mimetic, designed to inhibit multiple factors implicated in tumor-host cell interactions, including VEGF, FGF2, SDF-1α, P-selectin, and heparanase. A single s.c. dose of M402 effectively inhibited seeding of B16F10 murine melanoma cells to the lung in an experimental metastasis model. Fluorescent-labeled M402 demonstrated selective accumulation in the primary tumor. Immunohistological analyses of the primary tumor revealed a decrease in microvessel density in M402 treated animals, suggesting anti-angiogenesis to be one of the mechanisms involved in-vivo. M402 treatment also normalized circulating levels of myeloid derived suppressor cells in tumor bearing mice. Chronic administration of M402, alone or in combination with cisplatin or docetaxel, inhibited spontaneous metastasis and prolonged survival in an orthotopic 4T1 murine mammary carcinoma model. These data demonstrate that modulating HSPG biology represents a novel approach to target multiple factors involved in tumor progression and metastasis.

Oregovomab maintenance monoimmunotherapy does not improve outcomes in advanced ovarian cancer.

PURPOSE: This phase III study tested the hypothesis that the CA-125-specific murine monoclonal antibody, oregovomab, administered as a monoimmunotherapy after front-line therapy in a selected ovarian cancer population would prolong time to relapse (TTR) and, ultimately, survival. PATIENTS AND METHODS: Patients with stage III to IV ovarian cancer with preoperatively elevated CA-125 and objectively defined characteristics were randomly assigned 4 to 12 weeks after front-line carboplatin and paclitaxel chemotherapy to maintenance monoimmunotherapy in a fully blinded protocol. Two mg of oregovomab or placebo was infused over 20 minutes at weeks 0, 4, and 8 and then 12 weeks until recurrence or up to year 5. Patients were evaluated with serial imaging and clinical evaluation for evidence of recurrence at quarterly visits. TTR was the primary end point. RESULTS: Three hundred seventy-three patients were accrued at more than 60 centers; 251 patients were assigned to oregovomab and 120 patients were assigned to placebo. The treatment arms were well balanced. There were no differences in the clinical outcomes between treatment groups. Median TTR measured from randomization after completion of chemotherapy for the integrated study was 10.3 months (95% CI, 9.7 to 13.0 months) for oregovomab and 12.9 months (95% CI, 10.1 to 17.4 months) for placebo (P = .29, log-rank test). The treatment was well tolerated. Grade 3 to 4 toxicity was reported in 24.6% of patients in the placebo group and 20.1% of patients in the oregovomab group, respectively. CONCLUSION: Although oregovomab has demonstrated bioactivity, the strategy of monoimmunotherapy is not effective as maintenance therapy after front-line treatment of a favorable subset of patients with advanced ovarian cancer. Future studies of this or other tumor-antigen specific immunization strategies should seek ways to further augment induced immunity.

Role of monoclonal antibodies in tumor-specific immunity.

Monoclonal antibodies, considered to be 'magic bullets' 20 years ago, may finally be realizing their full potential, particularly in the area of oncology, where > 10 monoclonal antibodies are approved for treatment. Monoclonal antibodies are being used to modulate tumor-specific immunity through several approaches: antibodies that direct cytotoxicity against the tumor through cellular or complement-mediated pathways; antibodies that directly modulate immune regulation; antibodies that alter tolerance to tumor antigens; and antibodies that act as antigen mimetics through the anti-idiotype network. Therapeutic progress in these areas is reviewed as well as the potential to combine these approaches with standard therapies.

Using antibodies in tumour immunotherapy.

The role of antibodies as therapeutic cancer vaccines includes two distinct approaches, which are summarised in this review, namely anti-idiotypic vaccines and antigen-antibody complex therapies. Bispecific antibodies directed against T cells or antigen-presenting cells are also referenced. The report focuses on theoretical issues, laboratory data on the mechanism of action, examples of humoral and cellular immune induction, and novel therapeutic advances in vaccine development. The biology of antigen processing and recent advances in the field of dendritic cell biology are critical to understanding the potent immune response induction. Future directions include combination therapies to manipulate immune regulatory mechanisms and to enhance clinical effects. Additional applications of antibodies targeting costimulatory or regulatory receptors on antigen-presenting cells and T cells, neutralising immune suppressive cytokines, and depleting T regulatory cells hold promise for future mono- and particularly combination therapies.

Biologic and immunologic therapies for ovarian cancer.

Biologic therapy of ovarian cancer has been conducted using nonspecific biologic response modifiers, cytokines, monoclonal antibodies (MAbs), vaccines, and gene therapy. Antibodies directed toward her2/neu have also been studied. Phase I and II gene therapy trials using adenoviral vectors containing a wild-type or modified p53 have shown that the treatment is well tolerated. Phase II and III trials are ongoing with MAbs directed against CA-125 (MAb B43.13) and an antibody directed against HMFG1 (anti-HMFG1-yttrium-90-labeled antibody). The trials have shown that these agents are well tolerated and that immunologic responses occur, although the ultimate clinical value of these agents remains to be determined. Prolonged survival after MAb B43.13 treatment has been correlated with changes in several immune parameters, including human antimurine antibody, Ab2, anti-CA-125 antibody development, and induced T-cell immunity. Clinical trials using a MAb directed toward the encoded products of her2/neu have shown minimal activity against ovarian cancer in a phase I and II trial conducted by the Gynecologic Oncology Group. Cytokine therapies have been administered systemically and intraperitoneally. Intracavitary interferon alfa, interferon gamma, and interleukin-2 alone or in combination with cytotoxic therapy in phase I and II trials demonstrated intraperitoneal lymphoid cell stimulation and produced antitumor responses. A randomized trial of chemotherapy with or without interferon gamma in primary treatment produced a response and a progression-free survival advantage in the arm that incorporated the interferon gamma, without a statistically significant benefit in overall survival. A phase III study of interferon gamma in combination with first-line chemotherapy is currently ongoing.

CA125- and tumor-specific T-cell responses correlate with prolonged survival in oregovomab-treated recurrent ovarian cancer patients.

OBJECTIVE: To evaluate immune responses and clinical outcomes for combined oregovomab and chemotherapy treatment of patients with recurrent ovarian cancer. METHODS: Patients with advanced recurrent ovarian cancer were administered oregovomab over 12 weeks before chemotherapy, then optionally concurrent with chemotherapy x 2. Antibody responses, including human anti-mouse antibody (HAMA), anti-idiotypic antibody (Ab2) and anti-CA125, were assessed by ELISA; T-cell responses to CA125, autologous tumor and oregovomab by interferon (IFN)-gamma enzyme-linked immunoSPOT (ELISPOT) were also evaluated. Clinical outcomes were recorded. RESULTS: Twenty patients were enrolled; median follow-up was 15.8 months. Oregovomab was well tolerated and did not produce drug-related serious adverse reactions. In 15/19 (79%) patients, robust treatment-emergent humoral responses were observed to the constant (HAMA) and variable region (Ab2) of oregovomab, and 2/19 (11%) patients developed anti-CA125 antibodies. Significant increases in T-cell responses were measured in 7/18 (39%) patients in response to CA125, in 5/8 (63%) patients in response to autologous tumor and in 9/18 (50%) patients in response to oregovomab. Immune responses appeared by week 12 (four doses) and were generally maintained or augmented in patients continuing combined treatment with oregovomab and chemotherapy. Median survival was 70.4 weeks (4.6-141.6 weeks), and the median progression-free interval was 11 weeks (2.6-114.6 weeks). Patients who mounted a T-cell response to CA125 and/or autologous tumor showed significantly improved survival (median not reached vs. 51.9 weeks, P = 0.002) compared to patients who did not. CONCLUSIONS: Oregovomab was well tolerated and induced multiple antigen-specific immune responses, maintained during concomitant chemotherapy. A significant survival benefit was observed in patients mounting a T-cell response to CA125 and/or autologous tumor.

Immune responses to murine monoclonal antibody-B43.13 correlate with prolonged survival of women with recurrent ovarian cancer.

OBJECTIVE: We evaluated the therapeutic efficiency of the murine monoclonal antibody-B43.13 in the treatment of patients with recurrent ovarian cancer. STUDY DESIGN: This was a retrospective study of immune responses and survival in 44 patients who were treated with technetium 99m-labeled monoclonal antibody-B43.13, a murine monoclonal antibody that is directed against the tumor-associated antigen CA125. Most patients were pretreated heavily. Biologic activity was quantified by the assay of immune responses to the human anti-murine antibodies against the monoclonal antibody-B43.13 variable region (Ab(2)) and antibodies that target the CA 125 antigen itself (anti-CA 125 antibody). RESULTS: More than one half of patients (56.8%) survived for >12 months after the first dose of monoclonal antibody B43.13; 34.1% of the patients survived >24 months. To date, 6 of the 44 patients are alive, with survival times of 4 to 7.5 years after the start of the antibody treatment. More than 60% of the evaluable patients met predefined criteria for robust, treatment-emergent human anti-murine antibodies and Ab(2) responses, and these responses were associated with improved survival rates. Median survival time increased approximately 3-fold for human anti-murine antibody responders (22.6 months) versus nonresponders (7.2 months; P <.0016, log-rank test) and 2-fold for Ab(2) responders (18.3 months) versus nonresponders (9.3 months). No serious drug-associated adverse events were reported. CONCLUSION: The associations between multiple types of immune response and improved clinical outcomes suggest that monoclonal antibody-B43.13 should be further evaluated for potential use as an immunotherapy for CA125-expressing malignancies.