Immune escape from NY-ESO-1-specific T-cell therapy via loss of heterozygosity in the MHC

Adoptive immunotherapy of tumors with T cells specific for the cancer-testis antigen NY-ESO-1 has shown great promise in preclinical models and in early stage clinical trials. Tumor persistence or recurrence after NY-ESO-1-specific therapy occurs, however, and the mechanisms of recurrence remain poorly defined. In a murine xenograft model of NY-ESO-1⁺ multiple myeloma, we observed tumor recurrence after adoptive transfer of CD8⁺ T cells genetically redirected to the prototypic NY-ESO-1_157-165 peptide presented by HLA-A*02:01. Analysis of the myeloma cells that had escaped from T cell control revealed intact expression of NY-ESO-1 and B2M, but selective, complete loss of HLA-A*02:01 expression from the cell surface. Loss of heterozygosity in the Major Histocompatibility Complex (MHC) involving the HLA-A locus was identified in the tumor cells, and further analysis revealed selective loss of the allele encoding HLA-A*02:01. Although loss of heterozygosity involving the MHC has not been described in myeloma patients with persistent or recurrent disease after immune therapies such as allogeneic hematopoietic cell transplantation (HCT), it has been described in patients with acute myelogenous leukemia who relapsed after allogeneic HCT. These results suggest that MHC loss should be evaluated in patients with myeloma and other cancers who relapse after adoptive NY-ESO-1-specific T cell therapy.

Phenotypic and transcriptional fidelity of patient-derived colon cancer xenografts in immune-deficient mice

Xenografts of human colorectal cancer (CRC) in immune-deficient mice have great potential for accelerating the study of tumor biology and therapy. We evaluated xenografts established in NOD/scid/IL2Rγ-null mice from the primary or metastatic tumors of 27 patients with CRC to estimate their capacity for expanding tumor cells for in vitro studies and to assess how faithfully they recapitulated the transcriptional profile of their parental tumors. RNA-seq analysis of parental human CRC tumors and their derivative xenografts demonstrated that reproducible transcriptional changes characterize the human tumor to murine xenograft transition. In most but not all cases, the human stroma, vasculature, and hematopoietic elements were systematically replaced by murine analogues while the carcinoma component persisted. Once established as xenografts, human CRC cells that could be propagated by serial transplantation remained transcriptionally stable. Three histologically atypical xenografts, established from patients with peritoneal metastases, contained abundant human stromal elements and blood vessels in addition to human tumor cells. The transcriptomes of these mixed tumor/stromal xenografts did not closely resemble those of their parental tumors, and attempts to propagate such xenografts by serial transplantation were unsuccessful. Stable expression of numerous genes previously identified as high priority targets for immunotherapy was observed in most xenograft lineages. Aberrant expression in CRC cells of human genes that are normally only expressed in hematopoietic cells was also observed. Our results suggest that human CRC cells expanded in murine xenografts have great utility for studies of tumor immunobiology and targeted therapies such as immunotherapy but also identify potential limitations.

Abstract B49: Autologous T cell responses against patient-derived colorectal cancer xenografts

Prognosis in colorectal cancer (CRC) correlates closely with the density of tumor infiltrating T lymphocytes (TIL) in the primary tumor, suggesting that the adaptive cellular immune system can influence the natural history of this disease. However, it is unclear if TIL in CRC comprise a non-specific inflammatory response, or if T cells in TIL are specifically reactive with antigens expressed on CRC tumor cells. To date the study of TIL interaction with autologous CRC cells has been hampered by the small numbers of tumor cells and TIL that can be obtained from CRC surgical samples. We have developed reliable methods for expanding primary human CRC tumor cells as xenografts in immune-deficient mice. Moreover, we have adapted next generation DNA sequencing of T cell receptor β chain CDR3 regions to define the clonal composition of CRC TIL with exquisite precision and depth. In combination with standard procedures for expanding T cells in vitro, we are using these techniques to dissect TIL-CRC tumor cell interactions at the cellular and molecular level.

The CD4+/CD8+ surface phenotype and TCRβ CDR3 sequence repertoire of TIL from 7 CRC tumor samples (a primary colon tumor from one patient, an ovarian metastasis from a second patient, and 4 non-contiguous hepatic metastases from a third patient), and from T cells in blood or normal adjacent tissue was evaluated by flow cytometry and next-generation sequencing, respectively. Flow cytometry revealed that CD4+ T cells comprised the majority of TIL expanded from the tumors from all 3 patients. Comparison of the TCRβ CDR3 sequence repertoires in the tumor and normal tissues demonstrated that the TIL were clonally distinct from the T cells present in blood or normal adjacent tissue. Moreover, extensive overlap in the repertoire of TIL isolated from the 4 hepatic metastases in patient 3 was observed, suggesting the presence in all 4 metastases of a population of T cells with similar antigenic specificity. We designed TCRβ CDR3 sequence-specific PCR primers to determine whether specific TCRβ sequences identified by next-generation sequencing were primarily found in the CD4+ or CD8+ subsets of TIL. The most common CDR3 sequences observed in TIL from the primary colon tumor of patient 1 were primarily found in the CD4+ subset, while the most common CDR3 sequences in the ovarian metastasis from patient 2 and the hepatic metastases from patient 3 were primarily found in the CD8+ subset.

The reactivity of CD8+ and CD4+ T cells expanded from CRC tumor, tumor-associated ascites fluid, normal adjacent tissue, and blood against autologous CRC tumor cells (freshly harvested from xenografts) and autologous dermal fibroblasts was assessed for in a series of 5 patients, including patients 1-3. T cells expanded from the 4 tissue compartments were evaluated by interferon-γ (IFN-γ) ELISPOT for reactivity with xenograft-derived autologous tumor cells or autologous dermal fibroblasts. No significant IFN-γ reactivity was seen when T cells from any compartment were cultured with autologous dermal fibroblasts. In all 5 patients, IFN-γ reactivity with autologous human epithelial cell adhesion molecule (EpCAM) sorted tumor cells was observed. This reactivity was more prominent in purified CD4+ T cells than in CD8+ T cells. No significant difference in the reactivity of T cells from various compartments against autologous tumor cells was observed, but T cells expanded from tumor associated ascites fluid showed overall lower levels of reactivity against all target cells.

Collectively, these results demonstrate that CRC TIL comprise a clonally distinct population of T cells containing both CD4+ and CD8+ T cells that are specifically reactive with autologous CRC tumor cells. However, T cells reactive with autologous tumor cells can also be isolated from other compartments such as normal adjacent tissue and peripheral blood.

Citation Format: Jeffrey Chou, Christie-Lynn L. Mortales, Sheila Ojeaburu, Raymond SW Yeung, Edus H. Warren. Autologous T cell responses against patient-derived colorectal cancer xenografts. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology: Multidisciplinary Science Driving Basic and Clinical Advances; Dec 2-5, 2012; Miami, FL. Philadelphia (PA): AACR; Cancer Res 2013;73(1 Suppl):Abstract nr B49.

Trace elemental imaging of coralline hydroxyapatite by laser-ablation inductively coupled plasma-mass spectroscopy

The determination of trace element concentrations, as well as their distribution in different biomaterials aimed for clinical applications, is a challenging task in both the areas of biological and materials research. In this research, LA-ICP-MS was employed for image mapping of the trace element distribution in a hydrothermally converted coralline hydroxyapatite material aimed for tissue-scaffolding applications. Quantification using synthetic matrix-matched standards was successfully applied for the determination and distribution of elements of interest, Sr and Mg, that influences the mechanical and biological properties of hydroxyapatite-based bone graft materials. The results showed that the instrument can successfully analyse trace elements and a relatively good image can be produced that identifies their distribution. The LA-ICP-MS method can provide an easy and effective tool, in the field of biomaterials with respect to distribution of trace elements, to better understand tissue-implant interactions, and will open up a new window for in vitro and in vivo analysis and imaging of different tissues and structures.

Strontium- and magnesium-enriched biomimetic β-TCP macrospheres with potential for bone tissue morphogenesis

During the last two decades, biogenic mineral ions have become important additives in treatments for bone regeneration and repair. Prominent among these is strontium, which is a potent suppressor of osteoclast bone resorption. Another is magnesium, which has a key influence in mineralization processes. The shells of benthic foraminiferans, hydrothermally converted into β-TCP, have been shown to effectively release a number of bone-promoting drugs at clinically relevant levels. In this study we characterized the effects of converted foraminiferan calcium dissolution and the concomitant release profile of intrinsic strontium and magnesium. We tested the effects of strontium- and magnesium-enriched macrospheres on human osteoblast (SaOS-2) and monocytoid (U937) cell lines, which can be induced to express equivalent phagocytic activities to osteoclasts. On dissolution in a biomimetic physiological solution, the macrospheres released biologically significant quantities of calcium and phosphate ions in the first 18 days. At 3 days, during which biogenic mineral ions are released, the number of U937 osteoclast-like monocyte cells decreased, while 4 days later the osteoblast cell number increased. These results show that strontium and magnesium naturally enriched macrospheres are capable of altering the metabolic activities of the cells regulating bone homeostasis. These unique macrospheres are natural origin bone void filler particles that resorb, and release physiologically significant levels of incorporated strontium, magnesium and calcium, which together make a uniquely multifunctional in situ remedy for bone regeneration and repair and the treatment of bone-wasting diseases.

NYESO-1/LAGE-1s and PRAME are targets for antigen specific T cells in chondrosarcoma following treatment with 5-Aza-2-deoxycitabine

BACKGROUND

Chondrosarcoma has no proven systemic option in the metastatic setting. The development of a non-cross-resistant strategy, such as cellular immunotherapy using antigen-specific T cells would be highly desirable. NY-ESO-1 and PRAME are members of the Cancer Testis Antigen (CTA) family that have been identified as promising targets for T cell therapy. LAGE-1 is a cancer testis antigen 90% homologous to NY-ESO-1, sharing the 157-165 A*0201 NY-ESO-1 epitope with its transcript variant, LAGE-1s. A number of CTA's have been induced using 5-Aza-2-Deoxycitabine (5-Aza-dC) in other cancers. We sought to evaluate the feasibility of targeting chondrosarcoma tumors using NY-ESO-1/LAGE-1s and PRAME specific T cells using 5-Aza-dC to induce antigen expression.

METHODS

We used 11 flash frozen tumors from the University of Washington tumor bank to test for the expression of NY-ESO-1, PRAME, LAGE-1s and LAGE-1L in chondrosarcoma tumors. Using four chondrosarcoma cell lines we tested the expression of these CTA's with and without 5-Aza-dC treatments. Finally, using NY-ESO-1/LAGE-1s and PRAME specific effectors that we generated from sarcoma patients, we evaluated the ability of these T cells to lyse A*0201 expressing chondrosarcoma cell lines in vitro both with and without 5-Aza-dC treatment.

RESULTS

A minority (36%) of chondrosarcoma tumors expressed either NY-ESO-1 or LAGE-1s at >10% of our reference value and none expressed PRAME at that level. However, in all four of the chondrosarcoma cell lines tested, NY-ESO-1 and PRAME expression could be induced following treatment with 5-Aza-dC including in cell lines where expression was absent or barely detectable. Furthermore, NY-ESO-1/LAGE-1s and PRAME specific CD8+ effector T cells were able to specifically recognize and lyse A*0201 expressing chondrosarcoma cell lines following 5-Aza-dC treatment.

CONCLUSION

These data suggest that adoptive immunotherapy in combination with 5-Aza-dC may be a potential strategy to treat unresectable or metastatic chondrosarcoma patients where no proven systemic therapies exist.

Strategies to defeat ketamine-induced neonatal brain injury

Studies using animal models have shown that general anesthetics such as ketamine trigger widespread and robust apoptosis in the infant rodent brain. Recent clinical evidence suggests that the use of general anesthetics on young children (at ages equivalent to those used in rodent studies) can promote learning deficits as they mature. Thus, there is a growing need to develop strategies to prevent this injury. In this study, we describe a number of independent approaches to address therapeutic intervention. Postnatal day 7 (P7) rats were injected with vehicle (sterile PBS) or the NMDAR antagonist ketamine (20 mg/kg). After 8 h, we prepared brains for immunohistochemical detection of the pro-apoptotic enzyme activated caspase-3 (AC3). Focusing on the somatosensory cortex, AC3-positive cells were then counted in a non-biased stereological manner. We found AC3 levels were markedly increased in ketamine-treated animals. In one study, microarray analysis of the somatosensory cortex from ketamine-treated P7 pups revealed that expression of activity dependent neuroprotective protein (ADNP) was enhanced. Thus, we injected P7 animals with the ADNP peptide fragment NAPVSIPQ (NAP) 15 min before ketamine administration and found we could dose-dependently reverse the injury. In separate studies, pretreatment of P6 animals with 20 mg/kg vitamin D(3) or a nontoxic dose of ketamine (5 mg/kg) also prevented ketamine-induced apoptosis at P7. In contrast, pretreatment of P7 animals with aspirin (30 mg/kg) 15 min before ketamine administration actually increased AC3 counts in some regions. These data show that a number of unique approaches can be taken to address anesthesia-induced neurotoxicity in the infant brain, thus providing MDs with a variety of alternative strategies that enhance therapeutic flexibility.

Enhanced survival of dopaminergic neuronal transplants in hemiparkinsonian rats by the p53 inactivator PFT-α

A key limiting factor impacting the success of cell transplantation for Parkinson's disease is the survival of the grafted cells, which are often short lived. The focus of this study was to examine a novel strategy to optimize the survival of exogenous fetal ventromesencephalic (VM) grafts by treatment with the p53 inhibitor, pifithrin-α (PFT-α), to improve the biological outcome of parkinsonian animals. Adult male Sprague-Dawley rats were given 6-hydroxydopamine into the left medial forebrain bundle to induce a hemiparkinsonian state. At 7 weeks after lesioning, animals were grafted with fetal VM or cortical tissue into the lesioned striatum and, thereafter, received daily PFT-α or vehicle injections for 5 days. Apomorphine-induced rotational behavior was examined at 2, 6, 9, and 12 weeks after grafting. Analysis of TUNEL or tyrosine hydroxylase (TH) immunostaining was undertaken at 5 days or 4 months after grafting. The transplantation of fetal VM tissue into the lesioned striatum reduced rotational behavior. A further reduction in rotation was apparent in animals receiving PFT-α and VM transplants. By contrast, no significant reduction in rotation was evident in animals receiving cortical grafts or cortical grafts + PFT-α. PFT-α treatment reduced TUNEL labeling and increased TH(+) cell and fiber density in the VM transplants. In conclusion, our data indicate that early postgrafting treatment with PFT-α enhances the survival of dopamine cell transplants and augments behavioral recovery in parkinsonian animals.

Descending necrotizing mediastinitis as a complication of odontogenic infection

Descending necrotizing mediastinitis (DNM) is a serious, life threatening complication that can occur from a common odontogenic infection. Even with advancements in antibiotics, diagnostic imaging, and surgical management, the mortality rate remains between 20 and 40%. It is imperative that the practitioner taking care of patients with odontogenic infections be sensitized to this potentially fatal complication. We report the successful management of a case of mediastinitis complicating an odontogenic infection in a 39-year-old male.