Surgical cytoreduction restores the antitumor efficacy of a Listeria monocytogenes vaccine in malignant pleural mesothelioma.

Recent studies suggest that immunotherapy may offer a promising treatment strategy for early-stage malignant pleural mesothelioma (MPM), but advanced tumor burden may limit the efficacy of immunotherapy. Therefore, we hypothesized that surgical cytoreduction could restore the efficacy of vaccine-based immunotherapy for MPM. We developed a murine model of MPM through transduction of a mesothelioma cell line with mesothelin. We used this model to evaluate the efficacy of a Listeria monocytogenes vaccine expressing mesothelin. Tumor growth was significantly inhibited at four weeks in animals vaccinated two weeks prior to tumor cell inoculation as compared to those given an empty vector control (1371 ± 420 mm(3) versus 405 ± 139 mm(3); p < 0.01). Mice vaccinated one week prior to tumor challenge also displayed significant reduction in tumor volume (1227 ± 406 mm(3) versus 309 ± 173 mm(3); p < 0.01). The vaccine had no effect when administered concurrently with tumor challenge, or after tumors were established. Flow cytometry showed reduced mesothelin expression in large tumors, as well as tumor-associated immunosuppression due to increased myeloid derived suppressor cells (MDSCs). These factors may have limited vaccine efficacy for advanced disease. Surgical cytoreduction of established tumors restored the antitumor potency of the therapeutic vaccine, with significantly reduced tumor burden at post-operative day 18 (397 ± 103 mm(3) versus 1047 ± 258 mm(3); p < 0.01). We found that surgery reduced MDSCs to levels comparable to those in tumor-naïve mice. This study demonstrates that cytoreduction surgery restores the efficacy of cancer vaccines for MPM by reducing tumor-related immunosuppression that impairs immunotherapy.

Kennedy GT ，Judy BF ，Bhojnagarwala P ，Moon EK ，Fridlender ZG ，Albelda SM ，Singhal S ... -  《-》

Clinical Response of Live-Attenuated, Listeria monocytogenes Expressing Mesothelin (CRS-207) with Chemotherapy in Patients with Malignant Pleural Mesothelioma.

Malignant pleural mesothelioma (MPM) is an aggressive cancer associated with poor prognosis. CRS-207 is a live-attenuated Listeria monocytogenes engineered to express mesothelin, a tumor-associated antigen highly expressed in MPM. CRS-207 induces antitumor immune responses and increases susceptibility of neoplastic cells to immune-mediated killing. Patients with unresectable MPM, ECOG 0 or 1, and adequate organ and pulmonary function were enrolled in this multicenter, open-label phase Ib study. They received two priming infusions of 1 × 109 CFU CRS-207, followed by pemetrexed/cisplatin chemotherapy, and CRS-207 booster infusions. Primary objectives were safety and induction of immune response. Secondary/exploratory objectives included tumor response, progression-free survival (PFS), overall survival (OS), immune subset analysis, and gene-expression profiling of tumor. Of 35 evaluable patients, 89% (31/35) had disease control with one complete response (3%), 19 partial responses (54%), and 10 stable disease (29%). The estimated median duration of response was 5.0 months (95% CI, 3.9-11.5). The median PFS and OS were 7.5 (95% CI, 7.0-9.9) and 14.7 (95% CI, 11.2-21.9) months, respectively. Tumor size reduction was observed post-CRS-207 infusion prior to chemotherapy in 11 of 35 (31%) patients. No unexpected treatment-related serious adverse events or deaths were observed. IHC analysis of pre- and post-CRS-207 treatment tumor biopsies revealed possible reinvigoration and proliferation of T cells, increased infiltration of dendritic and natural killer cells, increased CD8:Treg ratio, and a shift from immunosuppressive M2-like to proinflammatory M1-like macrophages following CRS-207 administration. Combination of CRS-207 and chemotherapy induced significant changes in the local tumor microenvironment and objective tumor responses in a majority of treated patients.

Hassan R ，Alley E ，Kindler H ，Antonia S ，Jahan T ，Honarmand S ，Nair N ，Whiting CC ，Enstrom A ，Lemmens E ，Tsujikawa T ，Kumar S ，Choe G ，Thomas A ，McDougall K ，Murphy AL ，Jaffee E ，Coussens LM ，Brockstedt DG ... -  《-》

Immuno-modulators enhance antigen-specific immunity and anti-tumor effects of mesothelin-specific chimeric DNA vaccine through promoting DC maturation.

As a tumor antigen, mesothelin (MSLN) can be identified in various malignancies. MSLN is potential for antigen-specific cancer vaccines. We generated a novel chimeric DNA vaccine using antigen-specific connective tissue growth factor lined with MSLN (CTGF/MSLN). The anti-tumor effects of the CTGF/MSLN DNA vaccine combined with anti-CD40 Ab and toll-like receptor 3 ligand-poly(I:C) were validated in an MSLN-expressing model. CTGF/MSLN DNA with anti-CD40Ab and poly(I:C) vaccinated mice demonstrated potent anti-tumor effects with longer survival and less tumor volumes. An increase in MSLN-specific CD8+ T cells and anti-MSLN Ab titers was also noted in CTGF/MSLN DNA with anti-CD40Ab and poly(I:C) vaccinated mice. The CTGF/MSLN DNA vaccine combined with immuno-modulator EGCG also generated potent anti-tumor effects. Immuno-modulators could enhance the antigen-specific anti-tumor effects of CTGF/MSLN DNA vaccine through promoting the DC maturation. In addition, MSLN-specific cell-based vaccine with AAV-IL-12 and the CTGF/MSLN DNA vaccine with anti-CD40Ab/polyp(I:C) generated more potent anti-tumor effects than the other combinational regimens. The results indicate that an MSLN-specific DNA vaccine combined with immuno-modulators may be an effective immunotherapeutic strategy to control MSLN-expressing tumors including ovarian and pancreastic cancers, and malignant mesothelioma.

Chen YL ，Chang MC ，Chiang YC ，Lin HW ，Sun NY ，Chen CA ，Sun WZ ，Cheng WF ... -  《-》

A novel mycobacterial Hsp70-containing fusion protein targeting mesothelin augments antitumor immunity and prolongs survival in murine models of ovarian cancer and mesothelioma.

Yuan J ，Kashiwagi S ，Reeves P ，Nezivar J ，Yang Y ，Arrifin NH ，Nguyen M ，Jean-Mary G ，Tong X ，Uppal P ，Korochkina S ，Forbes B ，Chen T ，Righi E ，Bronson R ，Chen H ，Orsulic S ，Brauns T ，Leblanc P ，Scholler N ，Dranoff G ，Gelfand J ，Poznansky MC ... -  《Journal of Hematology & Oncology》

A live-attenuated Listeria vaccine (ANZ-100) and a live-attenuated Listeria vaccine expressing mesothelin (CRS-207) for advanced cancers: phase I studies of safety and immune induction.

Le DT ，Brockstedt DG ，Nir-Paz R ，Hampl J ，Mathur S ，Nemunaitis J ，Sterman DH ，Hassan R ，Lutz E ，Moyer B ，Giedlin M ，Louis JL ，Sugar EA ，Pons A ，Cox AL ，Levine J ，Murphy AL ，Illei P ，Dubensky TW Jr ，Eiden JE ，Jaffee EM ，Laheru DA ... -  《-》