CVP alternating with fludarabine (CVP/F) chemotherapy prior to idiotype vaccination for follicular lymphoma (FL)

8065

Background: Reducing the tumor burden prior to vaccination facilitates an effective immune response (IR) against the idiotype in FL. In this context, we evaluated the efficacy and toxicity of a novel cytoreductive regimen, CVP/F. Methods: Newly diagnosed, advanced stage FL patients (pt) were treated with CVP (cyclophosphamide 400 mg/m2 PO d1–5, vincristine 2 mg d 1, prednisone 100 mg/m2 d1–5) alternating with F (25 mg/m2 IV d1–5) every 21 days for 2 cycles beyond best response (maximum 8). Pt judged to be cytoreduced adequately were vaccinated monthly × 5 with idiotype protein made from their FL. Results: Among 34 enrolled pt, median age was 45 years (yr), and FLIPI scores were: 18% low, 71% intermediate and 12% high. 38% pt had grade 1 and 62% had grade 2 FL. There were no toxic deaths or opportunistic infections. With 233 cycles (117 CVP and 116 F) given to 33 evaluable pt, neutropenic fever occurred in 7 cycles (3%). 20 cycles (17%) of CVP and 29 cycles (25%) of F were dose reduced for leukopenia. 18 pt (53%) achieved a CR (16) or CRu (2), and 13 pt (38%) had a PR. 22 pt (65%) treated with CVP/F proceeded to vaccination; 10 additional pt (29%) were vaccinated after secondary chemotherapy was given for further cytoreduction. At median follow-up of 11.2 yr, 15-yr overall survival (OS) was 85%. Two of 5 deaths occurred without lymphoma progression. TTF (time to treatment failure = second treatment, relapse, death) at 11 yr was 38%. Anti-idiotype antibody and T cell IR were seen in 44% and 31% pt, respectively. There were no differences in TTF or OS according to IR. Conclusions: CVP/ F was effective in advanced FL, comparing favorably with our historical experience with CVP in terms of CR rate, proportion proceeding to vaccination, TTF and OS after vaccination. This favorable outcome may have been due to the novel alternating CVP/F cytoreductive regimen, idiotype vaccination or both. The idiotype vaccine is now being tested in phase III trials. The CVP/F regimen also warrants further evaluation.

No significant financial relationships to disclose.

Combination immunotherapy with rituximab and local delivery of CpG oligonucleotide in a syngeneic murine model expressing human CD20

2502

Background: Immunostimulatory agents such as CpG oligonucleotides (CpG) may improve the efficacy of rituximab (R) by augmenting antibody-dependent cellular cytotoxicity. We have generated a murine B cell lymphoma expressing human CD20 (38C13-huCD20) for growth in syngeneic wild-type (WT) mice to efficiently study combination immunotherapy in an immunocompetent model. Methods: Groups of mice were inoculated s.c. with tumor cells and after tumor establishment, were treated with R on days 1 and 3, and either intratumoral (i.t.) or systemic (intraperitoneal, i.p.) CpG days 1, 2, 3, 5, 7 and 9. Tumor size was monitored daily and animals sacrificed when tumors reached 1.4 cm. Results: 38C13-huCD20 tumors were shown to express high levels of CD20 by flow cytometry, immunohistochemistry and microPET. While single agent R prevented growth of 100% of tumors when given on the day of inoculation, therapy of established tumors with either R or CpG alone provided no cures. In contrast, R plus i.t. CpG resulted in complete regressions (CR) of tumors in some mice. The route of CpG delivery was critical as only i.t., not systemic (i.p.) CpG combined with R led to CRs. All mice with CR survived challenge with a lethal dose of WT tumor cells, suggesting induction of immunity against non-human CD20 tumor antigens. Cyclophosphamide (Cy) was used to cytoreduce bulky tumors prior to treatment with R/CpG. Cy alone resulted in initial tumor shrinkage but no cures. In this stringent setting, there were no survivors after Cy/R. Long term tumor-free survivors were seen only in mice receiving i.t. CpG ± R. Addition of i.t. CpG significantly improved survival over Cy/R (p=0.018), while addition of i.p. CpG did not (p=0.24). Adding a second cycle of R/CpG i.t. on day 14 after Cy further improved survival (day 55) compared to 2 cycles of R alone (p=0.01) or 2 cycles of i.t. CpG alone (p=0.002). Conclusions: We have identified a novel combination immunotherapy resulting in eradication of an aggressive B cell lymphoma. Admininstration of CpG into the tumor bed was critical in enhancing the R effect. Ongoing studies are evaluating underlying immunologic mechanisms. Such models should allow identification of promising strategies appropriate for translation into clinical trials.

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Idiotype-encoding recombinant adenoviruses provide protective immunity against murine B-cell lymphomas

Vaccination with tumor-specific immunoglobulin or idiotype (Id) is a promising new form of immunotherapy for B-cell malignancies. Id protein vaccination has demonstrated clinical activity in B-cell lymphomas, yet it requires the laborious and time-consuming procedures of tumor-myeloma cell hybridization, large-scale in vitro culture, and protein purification. Recombinant adenoviruses are highly efficient and immunogenic gene transfer vehicles from which individualized vaccines can be rapidly assembled using polymerase chain reaction-amplified tumor Id genes. Id-encoding adenoviruses were evaluated as vaccines in 2 murine B-cell lymphoma models. A single injection of recombinant Id adenovirus provided protection from subsequent tumor challenge that was equivalent or superior to that afforded by Id protein vaccination. Protected mice had substantial serum titers of Id-specific antibodies. When used in conjunction with chemotherapy, vaccination also prolonged the survival of mice bearing pre-existing tumor. Mechanistic studies demonstrated that tumor protection was not dependent upon T cells. Importantly, in mice prevaccinated with an irrelevant adenovirus, tumor protection following vaccination with Id adenovirus was not significantly impaired. These findings have implications for the design of future lymphoma immunotherapy trials.

The history of the development of vaccines for the treatment of lymphoma

Exploitation of the immune system is an attractive strategy for developing selective lymphoma therapies. In the past several decades, increased knowledge of tumor immunology has granted investigators the tools to formulate a variety of lymphoma-specific vaccines. Vaccines targeting the tumor-specific immunoglobulin (idiotype) of B-cell lymphomas were the first to be developed, owing to successful active vaccination studies in animal models and clinical studies of passive anti-idiotype monoclonal antibodies. In initial clinical trials, patient-specific idiotype vaccines have been found to induce anti-idiotype immune responses that correlate with improved disease-free and overall survival and the reduction of the level of detectable residual disease. More recent strategies for improving the potency and practicality of idiotype vaccines are utilization of dendritic cells, recombinant idiotype proteins, and DNA vaccination. Custom-made vaccines utilizing whole autologous tumor cells are also being developed. Given the exciting results of these early lymphoma vaccine studies and the accelerated pace of immunologic research, it is hoped that vaccines will someday expand the armamentarium of effective lymphoma therapies.

Linkage of foreign carrier protein to a self-tumor antigen enhances the immunogenicity of a pulsed dendritic cell vaccine

The unique Ag-presenting capabilities of dendritic cells (DCs) make them attractive vehicles for the delivery of therapeutic cancer vaccines. While tumor Ag-pulsed DC vaccination has shown promising results in a variety of murine tumor models and early clinical trials, the optimal form of tumor Ag for use in DC pulsing has not been determined. We have studied DC vaccination using alternative forms of a soluble protein tumor Ag, the tumor-specific Ig idiotype (Id) expressed by a murine B cell lymphoma. Vaccination of mice with Id-pulsed DCs was able to induce anti-Id Abs only when the Id was modified to constitute a hapten-carrier system. DCs pulsed with Id proteins modified to include foreign constant regions, foreign constant regions plus GM-CSF, or linkage to keyhole limpet hemocyanin (KLH) carrier protein were increasingly potent in their ability to elicit anti-Id Abs. Vaccination with Id-KLH-pulsed DCs induced tumor-protective immunity superior to that obtained with Id-KLH plus a chemical adjuvant, and protection was not dependent upon effector T cells. Rather, protection was associated with the induction of high titers of anti-Id Abs of the IgG2a subclass, characteristic of a Th1 response. These findings have implications for the design of therapeutic Ag-pulsed DC vaccines for cancer immunotherapy in humans.

Dendritic cell vaccines for cancer immunotherapy

Human tumors express a number of protein antigens that can be recognized by T cells, thus providing potential targets for cancer immunotherapy. Dendritic cells (DCs) are rare leukocytes that are uniquely potent in their ability to present antigens to T cells, and this property has prompted their recent application to therapeutic cancer vaccines. Isolated DCs loaded with tumor antigen ex vivo and administered as a cellular vaccine have been found to induce protective and therapeutic anti-tumor immunity in experimental animals. In pilot clinical trials of DC vaccination for patients with non-Hodgkin's lymphoma and melanoma, induction of anti-tumor immune responses and tumor regressions have been observed. Additional trials of DC vaccination for a variety of human cancers are under way, and methods for targeting tumor antigens to DCs in vivo are also being explored. Exploitation of the antigen-presenting properties of DCs thus offers promise for the development of effective cancer immunotherapies.

Malignant germ cell tumors in men infected with the human immunodeficiency virus: natural history and results of therapy

PURPOSE

To determine how men infected with the human immunodeficiency virus (HIV) tolerate and respond to treatment for malignant germ cell tumors (GCTs), and how GCT histology and stage compare among HIV-infected versus non-HIV-infected men.

PATIENTS AND METHODS

Two hundred ninety-four cases of GCT diagnosed or treated from 1980 to 1993 were reviewed. Nine new cases among HIV-infected men were identified; these were analyzed together with six cases previously reported from our institution.

RESULTS

Low-stage tumors (stages I and IIA) comprised 67% of HIV-infected and 63% of non-HIV-infected cases. Sixty-seven percent of HIV-infected cases were seminomas versus 51% of non-HIV-infected cases. Ten patients had AIDS at the time of GCT diagnosis. Five patients underwent radiation therapy and one patient underwent retroperitoneal lymphadenectomy without complications. Seven patients received chemotherapy with four cycles of cisplatin, etoposide, and bleomycin (PEB) or cisplatin, vinblastine, and bleomycin (PVB) without excess cytopenias or new opportunistic infections. Of seven patients treated for advanced disease, there were five complete and two partial responses. Six patients have died of AIDS at a median of 20 months after diagnosis of GCT. The median follow-up time for surviving patients has been 42 months (range, 8 to 87) and all but one remain without evidence of active disease. In no case was a patient's HIV disease classification altered by antitumor therapy.

CONCLUSION

The natural history of GCTs is comparable in HIV-infected and non-HIV-infected men and standard therapy including orchiectomy, retroperitoneal lymph node dissection, radiation therapy, and chemotherapy is well tolerated.