Search

Patch grafting, a novel strategy for transplantation of stem/progenitor organoids into porcine livers, has been found successful also for organoid transplantation into other normal or diseased solid organs in pigs and mice. Each organoid contained ∼100 cells comprised of biliary tree stem cells (BTSCs), co-hepato/pancreatic stem/progenitors, and partnered with early lineage stage mesenchymal cells (ELSMCs), angioblasts and precursors to endothelia and stellate cells. Patch grafting enabled transplantation into livers or pancreases of ≥10

3556 Background: Molecular imaging of metabolic pathways critical for effector T cell response other than glucose could predict response to PD1 inhibitors. We have previously shown that high expression of tryptophan metabolic pathway enzymes in stage III/IV melanoma correlates with reduced abundance of tumor-infiltrating lymphocytes (TILs, ASCO 2019, e21014). Here we investigated C11-AMT, a PET tracer that images tryptophan metabolism, as a predictor of response to pembro in patients (pts) with PD1 inhibitor-naïve MM. Methods: In this trial (NCT03089606) pts must have had measurable MM by RECIST, have undergone IV contrast CT, FDG-PET, and C11-AMT PET scan (30-40 min dynamic imaging), plus a mandatory tumor biopsy prior to pembro treatment. Results: 21 pts (16 males; 15 stage IV; median age 61) had all 3 baseline scans and evaluable research biopsies. 13 pts were non-progressors (CR = 4, PR = 6, and SD = 3). At a median f/u of 13.7 mons (2.8-25.1+), 6 pts are dead from MM, 11 are alive without MM and 4 are alive with MM. 46 tumor lesions were assessed by all 3 scans. Of the pts with tumor lesion, C11-AMT PET SUVmax < 7 and skewness < +0.3 of the tumor lesion with the highest C11-AMT SUVmax was associated with non-progression by RECIST (SUVmax < 7/skewness < +0.3 in progressors vs. non-progressors; Fisher’s 2-tail test p= 0.055). The corresponding association between baseline FDG-PET (SUVmax < 14 and skewness < +0.3) with treatment response was insignificant ( p= 0.08). There was a weak (Spearman ρ= 0.33) but significant correlation ( p= 0.001) in SUVmax between FDG-PET and C11-AMT among the 46 tumors analyzed. There was no significant correlation between melanoma-specific expression of the tryptophan- (TPH1, TPH2, IDO1, TDO2, LAT1) and glucose-metabolizing enzymes (GLUT1, HK1, HK3) by immunohistochemistry. Response to pembro trends to associate with present TILs (Fisher’s p= 0.087). Conclusions: Baseline C11-AMT PET imaging using simple radiomics measures (highest metabolic activity, SUVmax, and tumor heterogeneity, skewness) may better predict clinical benefit from pembro in MM than FDG PET. Variability in C11-AMT’s SUVmax cannot be solely explained by FDG-PET’s SUVmax, suggesting that these two imaging modalities may provide complementary information about intratumoral metabolic dysregulation that may relate with pembro response. Texture analysis using LifeX v4.0 will be presented at the meeting. Clinical trial information: NCT03089606 .

BACKGROUND Previous results from our lab indicate a tumor suppressor role for the transmembrane protein with epidermal growth factor and two follistatin motifs 2 (TMEFF2) in prostate cancer (PCa). Here, we further characterize this role and uncover new functions for TMEFF2 in cancer and adult prostate regeneration. METHODS The role of TMEFF2 was examined in PCa cells using MatrigelTM cultures and allograft models of PCa cells. In addition, we developed a transgenic mouse model that expresses TMEFF2 from a prostate specific promoter. Anatomical, histological, and metabolic characterizations of the transgenic mouse prostate were conducted. The effect of TMEFF2 in prostate regeneration was studied by analyzing branching morphogenesis in the TMEFF2-expressing mouse lobes and alterations in branching morphogenesis were correlated with the metabolomic profiles of the mouse lobes. The role of TMEFF2 in prostate tumorigenesis in whole animals was investigated by crossing the TMEFF2 transgenic mice with the TRAMP mouse model of PCa and analyzing the histopathological changes in the progeny. RESULTS Ectopic expression of TMEFF2 impairs growth of PCa cells in Matrigel or allograft models. Surprisingly, while TMEFF2 expression in the TRAMP mouse did not have a significant effect on the glandular prostate epithelial lesions, the double TRAMP/TMEFF2 transgenic mice displayed an increased incidence of neuroendocrine type tumors. In addition, TMEFF2 promoted increased branching specifically in the dorsal lobe of the prostate suggesting a potential role in developmental processes. These results correlated with data indicating an alteration in the metabolic profile of the dorsal lobe of the transgenic TMEFF2 mice. CONCLUSIONS Collectively, our results confirm the tumor suppressor role of TMEFF2 and suggest that ectopic expression of TMEFF2 in mouse prostate leads to additional lobe-specific effects in prostate regeneration and tumorigenesis. This points to a complex and multifunctional role for TMEFF2 during PCa progression. Prostate 9999: XX–XX, 2015. © 2015 Wiley Periodicals, Inc.

e21014 Background: The ECHO-301/KEYNOTE-252 trial failed to show clinical benefit of adding epacadostat to pembrolizumab in PD-1 inhibitor-naïve MM. We reasoned that the expression of other TMEs and/or LAT1 by melanoma cells plays a more important role. Methods: Melanoma tissues from stage III/IV pts were stained for the 4 TMEs (TPH1, TPH2, TDO2, IDO1) and LAT1 by single-color immunohistochemistry. Tissues were scored for the status of tumor-infiltrating lymphocytes (TILs) and the expression of 5 proteins separately in melanoma cells and TILs (if present). Association between protein expression, TIL status, and melanoma-specific overall survival was performed. Results: Tissues from 87 pts (stage IV, n = 25) were available. Expression of all 4 TMEs and LAT1 was significantly higher in melanoma cells compared to TILs ( p< 0.001); TPH1, TPH2, and TDO2 expression in melanoma cells was significantly higher than IDO1 (p < 0.001). Lower TPH1 expression in melanoma cells was associated with presence of TILs. Multivariate analysis using a Cox proportional hazards model that included expression of the 5 proteins in melanoma cells showed that high IDO1 was a favorable and high LAT1 expression was an adverse prognostic factor. Conclusions: Expression of TMEs and LAT1 by melanoma cells may have more important role in metastatic melanoma by depleting an essential amino acid from the tumor microenvironment. Pharmacologic targeting of TPH1/TPH2 (e.g. telotristat) may be more clinically relevant in MM as opposed to IDO1 inhibition.