Tumor-associated stroma cell therapy in patients with pancreatic cancer potentiates therapeutic effect of tumor B-cell hybrid (TBH) auto-vaccines

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Background: Pancreatic Cancer (PC) tumor-associated stroma cells play an important role in PC’s immune surveillance escape. Secretion of Transforming Growth Factor β (TGFβ) and IL10 by PC tumor cells disturb the antigen presenting function of the stroma cells. It may explain the poor results of most immunotherapeutic approaches. Granger et al. reported a successful approach for treating small size pancreatic tumors, namely Mixed Lymphocyte Culture (MLC) cytoimplant. MLC cytoimplants, acting as a Th1 cytokine pump inside the tumor, are thought to revert the tumor-associated stroma cell dysfunction, and facilitate an immune attack. In view that TBH auto-vaccines have modest activity in advanced PC, we considered the possibility that a combination of MLC cytoimplant and TBH vaccines might potentiate the immune response. In this study we compared the response of MLC cytoimplant, TBH vaccines, and combinations of both therapies. Methods: 40 patients with advanced PC were treated: Group 1 MLC cytoimplan (10); Group 2 TBH vaccines (3); Group 3 one MLC cytoimplant and three TBH vaccines (9); Group 4 one MLC cytoimplant and six TBH vaccines (12) and Group 5 one MLC cytoimplant followed by two TBH immunizations, then second MLC cytoimplant followed by 4 TBH vaccines (6). Anti-tumor immune response was measured by Lymphocyte proliferation assay against autologous PC. Results: MLC cytoimplant combined with TBH vaccines appears to have synergistic and effective anti-tumor activity in advanced PC. Kaplan Meyer analysis showed a significant difference in the survival of group 4 as compared with the other four groups (P<0.001). After cytoimplant administration, 1/12 patients in Group 4 and 1/6 patients in Group 5 experienced transient bleeding episodes (lasting less than 12 hours). After the second MLC cytoimplant, all patients in Group 5 developed significant Graft Vs Host Disease (GVHD), an occurrence that probably contributed to the Group’s shorter survival when compared to Group 4’s survival. Conclusions: The observation that a second MLC cytoimplant leads to GVHD is consistent with a pro-inflammatory change in the tumor-associated stroma cells. MLC cytoimplant followed by TBH vaccines appear to prolong survival.

No significant financial relationships to disclose.

Tumor stem cell vaccine for NSCLC and GBM-assessment of feasibility, adverse events and efficacy

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Background: Only a small part of the total cell population of a malignancy has the potential to grow and regenerate the total tumor mass. The rest are only differentiated forms of those stem cells. This biologic characteristic seems to be responsible for the failure to achieve long term remission for several peptide based vaccines. Method: To overcome this obstacle, we have established a technique that uses tumor stem cells (TSC) to develop a TSC-B cell vaccine. To test efficacy and best administration form of this vaccine, we have proceeded as follow: First: Pieces from total or partial resections of GBM or NSCLC were mechanically dissociated to a single cell suspension. Cells were cultured in an appropriate tissue culture medium and allowed to grow for two weeks or until they reach a semi confluent stage. Then, cells were harvested and re-seeded. This procedure was repeated 6 to 24 weeks according to vitality and growth characteristics of cells. Finally, Tumor cells were fused with autologous B cells. The hybrid was kept in culture and used for an intra lymph node immunization every 3 weeks. To potentiate its action, 3 days prior to its administration we co-incubated the hybrid with either autologous dendritic cells or autologous mononuclear cells. Adverse events were evaluated by the “Common terminology criteria for Adverse Events (AE), 2004” developed by NIH. Definitions are available on the web at http://ctep.cancer.gov/reporting/ctc.html . Clinical efficacy of this procedure was evaluated according RESIST criteria for NSCLC and a combination of MRI and spectroscopy for GBM. Results: At present 8 patients with GBM with post surgical second relapse and who had received complete radiotherapy doses were treated. We have also treated 6 patients with NSCLC:4 with minimal residual disease and 2 with measurable residual disease. Patients have presented minor adverse events, mainly referred to inflammation of the injection site. The median survival rates registered to the present are 22 months for GBM patients and 3 years for patients with stage IV NSCLC who had minimal residual disease at the beginning of the treatment. Conclusion: A tumor stem cell vaccine seems to be a feasible and effective therapy with very low toxicity for the treatment of advanced GBM and NSCLC patients.

No significant financial relationships to disclose.