Christopher F. Nicodemus

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.

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.

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.

The Immune adjuvant properties of front-line carboplatin-paclitaxel: a randomized phase 2 study of alternative schedules of intravenous oregovomab chemoimmunotherapy in advanced ovarian cancer.

Oregovomab is a monoclonal antibody that recognizes CA125 and forms circulating immune complexes that can elicit immunity against both tumor antigen and tumor. This study was designed to assess combining this immunotherapy at 2 dosing schedules with front-line chemotherapy in patients with advanced ovarian cancer. Forty patients with stage III/IV carcinomas were randomized to receive a 2 mg oregovomab infusion either the same day [simultaneous infusion (SIM)] or 1 week after [1-week delayed (OWD)] standard carboplatin-paclitaxel chemotherapy at cycles 1, 3, and 5, then quarterly for up to 11 antibody doses. The primary end point was antibody response to oregovomab. Secondary end points included cellular immune response, response rate to front-line treatment, and progression-free survival. A different immune response pattern was observed between the SIM arm and the OWD arm, baseline plasma cytokines were balanced. Humoral immunity occurred more rapidly (P=0.0033) and with greater magnitude in the SIM arm. Absolute lymphocyte counts decreased in the SIM arm at cycles 3 and 5 compared with baseline. Treatment emergent CA125-specific cellular immunity was measured more commonly with SIM (P=0.04) and clinical parameters directionally favored this schedule. The immune responses were stronger than those measured in a previous maintenance monoimmunotherapy protocol. Immunotherapy-associated toxicity was minimal in this study. Front-line chemotherapy with carboplatin-paclitaxel has immune adjuvant properties when combined with oregovomab immunotherapy; however, schedule is important. SIM strategies of carboplatin and paclitaxel should be further studied with oregovomab and other antigen-specific cancer immunotherapy approaches.

TLR3 agonists as immunotherapeutic agents

The interaction of innate and adaptive immune responses is extremely complex and just beginning to be understood in detail. The tendency for biomedical research to establish reproducible models, cell systems and receptor pathways, and then to focus on these systems can sometimes result in opportunity that is not appreciated. The Toll-like receptor (TLR)3 pathway as a therapeutic target falls into this category. There is an immense body of data that has been developed for more than 40 years; all of which is highly relevant to the TLR3 story and yet most of which predates the elucidation of the TLR pathways. A new recognition of TLR3, its unique properties that distinguish it from other TLR pathways, the specificity of relevant and long-available TLR agonists, and new studies of this biology utilizing modern assay methodology suggest that this target may be especially valuable as an adjunct to multiple immunotherapy strategies currently in use or in development.

CA125 velocity at relapse is a highly significant predictor of survival post relapse: results of a 5-year follow-up survey to a randomized placebo-controlled study of maintenance oregovomab immunotherapy in advanced ovarian cancer.

This report presents final survival survey results from a previously reported study using oregovomab immunotherapy in patients with advanced ovarian epithelial cancer. Follow-up surveys to 5 years from randomization were collected for the cohort of stage III/IV ovarian cancer patients achieving initial remission who received subsequent maintenance immunotherapy with oregovomab or placebo. The relationship of time-to-relapse, survival postrelapse, and overall survival was analyzed. One hundred forty-five patients in the intent-to-treat population and the hypothesis generating subset of 67 patients (debulked to ≤2 cm, CA125 ≤65 U/mL before cycle 3, normal CA125 and no evidence of disease postchemotherapy) previously reported were evaluated for long-term outcomes. Patterns of relapse and survival were consistent in both groups for the intent-to-treat population. Median survival time was 57.5 months for oregovomab and 48.6 months for placebo with an adjusted hazard ratio of 0.72 (95% confidence interval, 0.41-1.25). Median survival has not been reached in the hypothesis generating subset of patients receiving oregovomab. Cox multivariate regression analysis identified velocity of CA125 rise at relapse to be a highly statistically significant predictor of postrelapse outcome (P=0.006). Although time-to-relapse may be a useful surrogate of survival in ovarian cancer immunotherapy studies, 5 years of follow-up has proved insufficient to permit a definitive survival analysis and it has been extended in ongoing phase III studies of oregovomab. Velocity of CA125 rise at relapse is a highly significant predictor of survival after relapse.

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

BackgroundProstate 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.MethodsBinding characteristics of the antibody were determined by ELISA and flow cytometry. In vitro degranulation was determined by the release of β-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.ResultsThe 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.ConclusionsThe 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.

Toll-like receptor-3 as a target to enhance bioactivity of cancer immunotherapy.

OBJECTIVE The purpose of this study was to explore the potential of toll-like receptor-3 stimulation, with polyI:C(12)U (poly[l].poly[C(12),U]; rintatolimod [Ampligen; Hemispherx Biopharma, Philadelphia, PA]) to enhance bioactivity of cancer immunotherapies. STUDY DESIGN Several models of immune activation were assessed with polyI:C(12)U at concentrations that were achieved clinically. Dendritic cell maturation and antigen-specific immune responses were evaluated in vitro and in a murine model. The potential for polyI:C(12)U to enhance antibody-dependent cellular cytotoxicity against tumor was also evaluated. RESULTS Dendritic cells are matured and T-cell stimulation is enhanced in the presence of polyI:C(12)U. In addition, polyI:C(12)U induced the release of proinflammatory chemokines and cytokines. Prostate-specific antigen-specific T-cell and antibody responses were enhanced significantly in a BALB/c prostate-specific antigen transgenic mouse model. Finally, rituximab-mediated antibody-dependent cellular cytotoxicity against tumor targets was improved significantly by the addition of polyI:C(12)U. CONCLUSION PolyI:C(12)U shows promise as a potential agent for selective enhancement of effect with currently available and future cancer immunotherapies.

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 (ECDHER2) 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 ECDHER2. 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.

Monoclonal antibody therapy of ovarian cancer

Despite advances in understanding and treatment, ovarian cancer remains a major cause of cancer mortality worldwide. Debulking surgery and paclitaxel/carboplatin chemotherapy induce good initial responses in most patients, although most cases of advanced disease are not controlled. Monoclonal antibodies hold promise as a potential incremental advance for the treatment of the disease. Antibodies can be used to stimulate the immune response, target tumor-specific receptors to induce antibody-dependent cellular cytotoxicity or interfere with biologic pathways. They can also be used to deliver therapeutic radioisotopes to malignant cells. Oregovomab is in Phase III clinical trials as a consolidation treatment post front-line therapy to trigger tumor-specific cellular immunity. Bevacizumab, which blocks vascular endothelial growth factor, will be entering Phase III as an adjuvant to front-line chemotherapy with a direct effect on angiogenesis. Additional immunostimulating, immune counter-regulatory and receptor-targeting approaches are also reviewed. The family of epidermal growth factor receptors including epidermal growth factor receptor 1 (HER-1) and 2 (HER-2) are both expressed in ovarian cancer and are the subject of ongoing research and development. The recent disappointing results with 90-yttrium-labeled anti-HMFG by single intraperitoneal administration have left the radiopharmaceutical field without a Phase III candidate. Identification of novel targets may advance this therapeutic area in the future. The rapid advances in the fields of immunoregulation and tumor biology should permit an accelerated introduction of antibodies for the treatment of ovarian cancer. These antibodies could complement novel small molecules that are also in development.