Abstract 4515: Metabolic stress sensor MondoA mediates in vivo aggressiveness of common ALL by induction of HIF1α

Tumor cells evolve adaptive mechanisms to survive hypoxia, nutrient deprivation, oxidative or genotoxic stress to ultimately drive tumor progression (Sorensen et al. 2015). We previously described MondoA (also known as MLXIP, MAX like protein X interacting protein) as a metabolic stress sensor, required for leukemogenesis. Lymphocytes, in particular B Lymphocytes are adapted to hypoxic environments from their very beginning. They are destined to travel from the hypoxic bone marrow via normoxic peripheral blood to hypoxic lymph nodes. They thus are specialized in glycolysis to compensate the lack of oxidative phosphorylation under hypoxic conditions. Leukemic counterparts of B-lymphocytes exploit these features for their survival. Glucose-derived metabolites control the nuclear activity of the transcription factor MondoA. Here we report on the expression of MondoA in common B-cell acute lymphoblastic leukemia (cALL) compared to other malignancies, its role in malignancy of cALL in vivo, downstream pathways and correlation with relapse risk.

Methods. Our human/murine xenotransplantation model with immunodeficient RAG2-/-gc-/- mice was used (Richter et al. 2009). NALM6 and 697 cALL lines were lentivirally transduced with MondoA short hairpin RNA. Upon successful MondoA knock down (KD), KD and control lines were injected into the mice; CD10+ blasts in blood, spleen and marrow were assessed.

Results. We found MondoA to be most strongly expressed in pediatric cALL and AML. Moreover MondoA expression was high in gastrointestinal stromal tumors and alveolar rhabdomyosarcoma. MondoA KD in cALL cell lines and their subsequent analysis in xenograft mice resulted in a reduced number of leukemic blasts in blood, marrow and spleen. Spleen size and weight normalized in mice after MondoA KD. Further microarray analysis revealed an enrichment of glycolytic and hypoxia response gene sets by MondoA. Moreover, HIF1a induction under hypoxia required MondoA. We demonstrate that hypoxia facilitates vincristine resistance of cALL. MondoA is induced under hypoxia and confers cALL cells chemotherapeutic resistance. Tied to these results, MondoA overexpression correlated with relapse risk; its expression was 63% higher in the very high-risk group as compared to the non-high-risk group of cALL. In conclusion, our findings demonstrate that MondoA maintains leukemic burden and aggressiveness of cALL in vivo possibly by modulating metabolic and hypoxia stress response, in particular by induction of HIF1a.

Citation Format: Alexandra A. Sipol, Thomas G. Grunewald, Juliane Schmaeh, Monique L. den Boer, Rebeca Alba Rubío, Michaela Baldauf, Caroline Wernicke, Martin Horstmann, Gunnar Cario, Günther Richter, Stefan Burdach. Metabolic stress sensor MondoA mediates in vivo aggressiveness of common ALL by induction of HIF1α [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4515. doi:10.1158/1538-7445.AM2017-4515

Ewing sarcoma partial regression without GvHD by chondromodulin-I/HLA-A*02:01-specific allorestricted T cell receptor transgenic T cells

Background: Chondromodulin-I (CHM1) sustains malignancy in Ewing sarcoma (ES). Refractory ES carries a dismal prognosis and patients with bone marrow (BM) metastases do not survive irrespective of therapy. We assessed HLA-A*02:01/CHM1-specific allorestricted T cell receptor (TCR) wild-type and transgenic cytotoxic (CD8⁺) T cells against ES. Patients and Methods: Three refractory HLA-A2⁺ ES patients were treated with HLA-A*02:01/peptide-specific allorepertoire-derived (i.e., allorestricted) CD8⁺ T cells. Patient #1 received up to 4.8 × 10⁵/kg body weight HLA-A*02:01^- allorestricted donor-derived wild-type CD8⁺ T cells. Patient #2 received up to 8.2 × 10⁶/kg HLA-A*02:01^- donor-derived and patient #3 up to 6 × 10⁶/kg autologous allorestricted TCR transgenic CD8⁺ T cells. All patients were treated with the same TCR complementary determining region 3 allorecognition sequence for CHM1 peptide 319 (CHM1³¹⁹). Results: HLA-A*02:01/CHM1³¹⁹-specific allorestricted CD8⁺ T cells showed specific in vitro lysis of all patient-derived ES cell lines. Therapy was well tolerated and did not cause graft versus host disease (GvHD). Patients #1 and #3 showed slow progression, whereas patient #2, while having BM involvement, showed partial metastatic regression associated with T cell homing to involved lesions. CHM1³¹⁹ TCR transgenic T cells could be tracked in his BM for weeks. Conclusions: CHM1³¹⁹-TCR transgenic T cells home to affected BM and may cause partial disease regression. HLA-A*02:01/antigen-specific allorestricted T cells proliferate in vivo without causing GvHD.

Abstract 2462: MondoA mediates in vivo aggressiveness of common ALL and may serve as a T-cell immunotherapy target

Oncogene addiction provides ideal targets for immunotherapy. We previously described MondoA (also known as MLXIP, MAX like protein X interacting protein) as a metabolic stress sensor, required for leukemogenesis. Here we report on the expression of MondoA in common acute lymphoblastic leukemia (cALL) compared to other malignancies, its role in malignancy of cALL in vivo, downstream pathways and correlation with relapse risk. Given the non-accessibility of transcription factors by drugs or chimeric antigen receptor transgenic T cells (CARs), we tested the targetability of MondoA by allo-restricted, peptide specific T cells.

Our human/murine xenotransplantation model with immunodeficient RAG2-/-gc-/- mice was used (Richter et al. 2009). NALM6 and 697 cALL lines were lentivirally transduced with MondoA short hairpin RNA (shRNA). Upon successful MondoA knock down (KD), KD and control lines were injected into the mice; CD10+ blasts in blood, spleen and marrow were assessed. MondoA specific T cells were generated by priming of donor HLAA0201 negative (A2-) T-cells with A2+ dendritic cells bearing MondoA peptides, multimer-based sorting and subcloning of A2-CD8+ T-cells. For priming of T cells, five MondoA peptides were chosen by SYMPEITHI, BIMAS and NetCTL1.2. analyses. Peptide 428 stabilized best A2 expression on TAP-deficient T2 cells. Specificity and functionality of T cell clones were tested by ELISpot interferon gamma (IFg) and granzyme B assays with six MondoA+ leukemia lines (A2+, A2-). Off target effects of MondoA specific T-cell clones were assessed by IFg reactivity against the MondoA expressing A2+ NALM6 cell line vs. A2+ and A2- EBV immortalized lymphoblastoid cell lines from six donors. Peptide homology was assessed with BLAST algorithms in SWISSPROT.

We found MondoA to be most strongly expressed in pediatric cALL and AML. Moreover MondoA expression was high in gastrointestinal stromal tumors and alveolar rabdomyosarcoma. MondoA KD in cALL cell lines and their subsequent analysis in xenograft mice resulted in a reduced number of leukemic blasts in blood, marrow and spleen. Spleen size and weight normalized in treated mice after MondoA KD. Further microarray analysis revealed an induction of aerobic glycolysis switch genes and hypoxia-response by MondoA. Consequently, HIF1A stabilization required MondoA expression and tied to these results, MondoA overexpression correlated with relapse risk; its expression was 63% higher in the very high-risk group as compared to the non-high-risk group of cALL. Therapeutically, MondoA-derived peptide antigens and A2+ cALL lines were successfully recognized and killed by specific, allo-restricted CD8+ T cells.

In conclusion, our findings demonstrate that MondoA maintains leukemic burden and aggressiveness of cALL in vivo possibly by modulating metabolic and hypoxia stress response. Moreover, we identified MondoA as a promising target for immunotherapy of cALL.

Citation Format: Alexandra Sipol, Thomas G. P. Grunewald, Juliane Schmaeh, David Schirmer, Monique L. den Boer, Rebeca Alba Rubío, Michaela Baldauf, Caroline Wernicke, Hans-Jochem Kolb, Martin Horstmann, Gunnar Cario, Guünther Richter, Stefan Burdach. MondoA mediates in vivo aggressiveness of common ALL and may serve as a T-cell immunotherapy target. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2462.

Transgenic antigen-specific, HLA-A*02:01-allo-restricted cytotoxic T cells recognize tumor-associated target antigen STEAP1 with high specificity

Pediatric cancers, including Ewing sarcoma (ES), are only weakly immunogenic and the tumor-patients' immune system often is devoid of effector T cells for tumor elimination. Based on expression profiling technology, targetable tumor-associated antigens (TAA) are identified and exploited for engineered T-cell therapy. Here, the specific recognition and lytic potential of transgenic allo-restricted CD8(+) T cells, directed against the ES-associated antigen 6-transmembrane epithelial antigen of the prostate 1 (STEAP1), was examined. Following repetitive STEAP1(130) peptide-driven stimulations with HLA-A*02:01(+) dendritic cells (DC), allo-restricted HLA-A*02:01(-) CD8(+) T cells were sorted with HLA-A*02:01/peptide multimers and expanded by limiting dilution. After functional analysis of suitable T cell clones via ELISpot, flow cytometry and xCELLigence assay, T cell receptors' (TCR) α- and β-chains were identified, cloned into retroviral vectors, codon optimized, transfected into HLA-A*02:01(-) primary T cell populations and tested again for specificity and lytic capacity in vitro and in a Rag2(-/-)γc(-/-) mouse model. Initially generated transgenic T cells specifically recognized STEAP1(130)-pulsed or transfected cells in the context of HLA-A*02:01 with minimal cross-reactivity as determined by specific interferon-γ (IFNγ) release, lysed cells and inhibited growth of HLA-A*02:01(+) ES lines more effectively than HLA-A*02:01(-) ES lines. In vivo tumor growth was inhibited more effectively with transgenic STEAP1(130)-specific T cells than with unspecific T cells. Our results identify TCRs capable of recognizing and inhibiting growth of STEAP1-expressing HLA-A*02:01(+) ES cells in vitro and in vivo in a highly restricted manner. As STEAP1 is overexpressed in a wide variety of cancers, we anticipate these STEAP1-specific TCRs to be potentially useful for immunotherapy of other STEAP1-expressing tumors.