Some interesting 2007 SNO Abstracts:
IM-29. TEMOZOLOMIDE THERAPY INDUCES AN INCREASE IN REGULATORY T-CELLS WITHOUT ABBROGATING A SPECIFIC TUMOR ANTIGEN IMMUNE RESPONSE IN PATIENTS WITH GBM
Gary Archer,1 Duane Mitchell,1 Amy Heimberger,2 Henry Friedman,1 David Reardon,3 James Vredenburgh,4 Mark Gilbert,5 Allan Friedman,6 Raymond Sawaya,2 Kenneth Aldape,2 Darell Bigner,1 and John Sampson3; 1Duke University, Durham, NC, USA; 2University of Texas M.D. Anderson Cancer Center, Houston, TX, USA; 3Durham, NC, USA; 4Duke University Medical Center, Durham, NC, USA; 5Houston, TX, USA; 6Surgery, Duke University, Durham, NC, USA
Traditional dogma would suggest that the combination of immuno- therapy with cytotoxic chemotherapy would be domed to failure due to the induced lymphopenia accompanying chemotherapy. However new para- digms are emerging that suggest that immunotherapy may benefit from this induced lymphopenia if prior thought is given to the timing of the two agents. We have previously carried out a Phase II clinical trial for patients with newly diagnosed GBM that are EGFRvIII positive at Duke and M.D. Anderson. In this trial patients with newly diagnosed, completely resected GBM were vaccinated with an EGFRvIII-speci c peptide q2 weeks 3 3 after radiation (XRT) (~60Gy) and Temozolomide (TMZ) (75mg/m2/d) and then monthly until progression. The initial finding of this trial was a median time to progression of 64.5 weeks (p , 0.0001, compared with a matched control group) and a median survival of 126.1 weeks. Immunomonitoring showed the induction of peptide specific humoral immune response. The recurrent tumors in the vaccinated patients with shown to be EGFRvIII negative by immunohistochemistry. In a second Phase II trial, the same patient population was vaccinated as before, q2 weeks 3 3 after radiation (XRT) (~60Gy) and TMZ (75mg/m2/d), and then monthly with the addition of 5 day TMZ cycles (200mg/m2/d). In these patients the TMZ induces a transient, Grade 3 lymphopenia (, 500 cells/mL) in 70% of patients after the rst TMZ cycle with nadirs occurring 14–21 days after treatment (n 5 10). Regulatory T cell (TReg) (CD41CD2511CD45RO1FOXP31) levels increased from 5.2 1 1.5% (3.3–7.5) to 11.8 1 2.6% (6.9–13.8) (p 5 0.0004; paired t-test) with TMZ and XRT and averaged 12.2 1 4.0% (6.4–18.1) after the second TMZ cycle (p 5 0.007) (n 5 6). Despite these fundings, in patients assayed, both humoral and cellular EGFRvIII-specific immune responses appear to be enhanced with TMZ. Median survival and TTP after vaccination is 22.1 weeks with no patients progressing (n 5 8). These initial results demonstrate that both chemotherapy and immunotherapy can be delivered concurrently without negating the effects of immunotherapy. TMZ-induced lymphopenia in patients with GBM may prove to be synergistic with a tumor specific peptide vaccine.
IM-30. A PHASE II CLINICAL TRIAL TO TEST THE EFFICACY OF DCVax-BRAIN, AUTOLOGOUS DENDRITIC CELLS PULSED WITH AUTOLOGOUS TUMOR LYSATE, FOR THE TREATMENT OF PATIENTS WITH GLIOBLASTOMA MULTIFORME
?Marnix Bosch,1 Alton Boynton,1 Robert Prins,2 and Linda Liau3; 1Northwest Biotherapeutics, Inc., Bothell, WA, USA; 2University of California, Los Angeles, CA, USA; 3CA, USA
Northwest Biotherapeutics Inc. has initiated a Phase II clinical trial to test the activity and ef cacy of DCVax-Brain, autologous dendritic cells pulsed with autologous tumor cell lysate, for the treatment of patients with newly diagnosed glioblastoma multiforme (GBM). GBM is the most aggressive form of brain cancer, with median time to tumor progression (TTP) of approximately 8 months and median survival time of 15–18 months. Patients treated with DCVax-Brain in Phase I trials at UCLA have median TTP of 18 months (p , 0.00001, log-rank) and median survival times of 33.8 months (p 5 0.0015, log-rank). Twenty-five percent of patients treated in these trials are alive for more than 42 months without progression. Evidence for immune responses induced by DCVax-Brain included detection of CTL responses and tetramer analysis of CD81 T cells. The trial will enroll 141 patients at 15 institutions in the United States over approximately 9 months. Patients are screened for eligibility during standard primary treatment consisting of surgery, external beam radiation therapy and concurrent temozolomide, and eligible patients are randomized to the treatment arm or the control arm at a 2:1 ratio. Patients in the treatment group will receive immunizations at frequent intervals, as well as continued adjuvant temozolomide. The primary endpoint is progression-free survival (PFS), and the secondary endpoint is overall survival (OS). Other secondary endpoints include safety, as well as the monitoring of immune responses induced by DCVax-Brain. This is the first large, multicenter, randomized trial to test the efficacy of dendritic cell-based immunotherapy for primary brain cancer.
IM-11. B CELLS ARE REQUIRED FOR PRESENTATION OF TUMOR ANTIGEN TO T CELLS AND FOR T CELL– DEPENDENT TUMOR REGRESSION
?James Curtin, Tamer Fakhouri, Chunyan Liu, Pedro Lowenstein, and Maria Castro; GTRI, Cedars-Sinai Medical Center, Los Angeles, CA, USA
B cells can present foreign antigen to nai¨ve T cells and stimulate T cell proliferation and clonal expansion in response to infectious agents. However, the role of B cells as brain tumor antigen presenting cells is not clear. Immunotherapy against brain tumors must first overcome immune igno- rance to tumor antigen. We have successfully induced T cell–dependent brain tumor regression by the intratumoral expression of Fms-like tyrosine kinase 3 ligand (Flt3 ligand) and Herpes Simplex Virus 1 Thymidine Kinase (TK) (p , 0.001, One Way ANOVA). In this study, we demonstrate that B cells are necessary to mount effective, tumor specific T cell immune responses in vivo. We found that bone-marrow-derived CD191 B cells infiltrated syngeneic GL26 brain tumors, in both saline and Flt3L and TK treated mice. We found that tumor in ltrating B cells engulfed CellTracker Green-labeled tumor antigen and con rmed that B cells containing Cell- Tracker Green labeled tumor antigen were present in the draining (cervical) lymph nodes. This suggested that B cells can endocytose tumor antigen in the brain tumor and traffic from the tumor to the draining lymph nodes (DLN). We found that intratumoral expression of Flt3L and HSV1–TK increased the total number of B cells in the DLN and we also found that B7–1 and B7–2 was upregulated on B cells in the DLN 7 days after treat- ment with Flt3L and TK compared with saline-treated control mice. We observed significant (p , 0.01, One Way ANOVA) increases in the total number of tumor-infiltrating T cells in wild type C57BL/6 mice 7 days after treatment with Flt3L and TK. Moreover, we used ELISPOT to determine that while IFN?-producing tumor antigen–speci c T cells were increased in wild type mice, no such increase was observed in B cell–deficient mice bearing GL26 tumors and treated with Flt3L and TK. We did not detect any increase in tumor speci c antibodies in the sera of treated mice, nor did we observe any increase in the presence of immunoglobulins that opsonized GL26 cells that we had isolated from the brains of Flt3L and TK treated mice, compared with saline-treated control mice. Together, our data sug- gest that the primary role of B cells in brain tumors treated with Flt3L and TK is to initiate T cell–dependent tumor regression. They may do this either by directly presenting tumor antigen to T cells or by traf cking tumor antigen from the tumor to the DLN where DC can present the antigen to T cells. In conclusion, our data support the hypothesis that B cells are tumor antigen–presenting cells and are required for the clonal expansion of tumor antigen–specific T cells and brain tumor regression. Supported by NIH/NINDS Grant 1R01 NS44556.01, Minority Supplement NS445561; 1R21-NSO54143.01; 1UO1 NS052465.01to M.G.C.; NIH/NINDS Grants 1 RO1 NS 054193.01; RO1 NS 42893.01; U54 NS045309-01, and 1R21 NS047298-01 to P.R.L.
IM-12. SYSTEMIC IMMUNOLOGICAL MEMORY ELICITED BY AD.FLT3L AND AD.TK TREATMENT OF RAT INTRACRANIAL GLIOMA RESULTS IN REGRESSION OF A SECOND TUMOR IMPLANTED IN THE PERIPHERY
A.K.M. Muhammad, Gwendalyn King, James Curtin, Marianela Candol , Chunyan Liu, Kurt Kroeger, Pedro Lowenstein, and Maria Castro; GTRI, Cedars-Sinai Medical Center, Los Angeles, CA, USA
Recurrence of human glioblastoma multiforme (GBM) is a common phenomenon that renders the outcome of currently available treatment modalities, including surgery, radiotherapy and chemotherapy margin- ally effective. We have developed a gene therapy strategy that combines conditional cytotoxicity (Thymidine kinase, TK) and immune stimulation utilizing Flt3 ligand (Flt3L) to treat very large syngeneic, intracranial GBM model (Ali et al., Cancer Res., 2005, 65:7194–7204). The combined gene therapy not only resulted in .80% survival of treated animals bearing a very large intracranial GBM, but also induced CD81 T cell dependent immunological memory that was capable of eliminating a second tumor implanted into the contra lateral hemisphere of the long-term (over 60 days) survivors. In the present study, we evaluated the ef cacy of such treatment in preventing growth of a second tumor implanted outside the neuroaxis. Male Lewis rats (200–250 g; Harlan, Indianapolis, IN, USA) were injected with 4,500 CNS-I cells into the striatum (11 mm anterior from bregma, 13 mm lateral and –5 mm from dura). Nine days later, they were treated with intratumoral injection of Ad.TK and Ad.Flt3L (1 3 108 pfu each); the controls received saline. Twenty-four hours later, gancyclovir (25 mg/ kg) was injected i.p. twice daily for 10 consecutive days. All saline treated control animals succumbed to tumor by day 20 and 80 % of the TK-Flt3L treated rats survived long term (p , 0.05). The long-term survivors were rechallenged with CNS-I cell (3 3 106) implanted in the anks; nai¨ve rats implanted with CNS- I cell in anks served as controls. The size of the tumor was measured daily in both groups for 10 days, that is, until the control tumors started regressing in size due to ischemic necrosis as revealed by H&E staining. The volume of the tumor mass (mm3; mean 6SD) was estimated to be 13.0 63.3, 13.7 62.8, 11.5 65.9, 1.7 60.7, and 0.3 60.2 in treated and 26.3 62.5, 52.1 64.2, 127.5 614.5, 426.1 636.3, and 203.8 634.3 in control groups at post implantation day 2, 4, 6, 8, and 10, respectively. The inter-group difference in tumor volume mass was signi cantly different. Employing irradiated CNS-I cells, delayed type hypersensitivity (DTH) reaction was seen to be present in long-term survivors whereas it was absent in saline treated controls. These findings suggest that the long-term immunological memory induced by our combined gene therapy is capable of causing regression of a second tumor implanted peripherally two months after treatment of the primary intracranial tumor mass and attest to the systemic nature of the anti-GBM immune response elicited by the combined Flt3L/TK (plus GCV) gene therapy. Brains of long-term survivors displayed no residual tumor. We detected CD681 macrophages at and around tumor regression scar but CD81 T cells were not seen, indicating that tumor regression results in limited damage to the brain parenchyma and low level, site-speci c innate in ammation. In conclusion, gene therapy combining TK and Flt3L can elicit a powerful systemic anti-GBM immune response and appears to be a promising adjuvant for the treatment of GBM. Supported by NIH/NINDS Grant 1R01 NS44556.01, Minority Supplement NS445561; 1R21-NSO54143.01; 1UO1 NS052465.01 to M.G.C.; NIH/NINDS Grants 1 RO1 NS 054193.01; RO1 NS 42893.01; U54 NS045309–01, and 1R21 NS047298-01 to P.R.L
