3 results on '"Megan T. Hoffman"'
Search Results
2. Biomarkers of pembrolizumab efficacy in advanced anal squamous cell carcinoma: analysis of a phase II clinical trial and a cohort of long-term responders
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Jeffrey A Meyerhardt, Sunil Kumar, Jessica A Zerillo, Aparna Parikh, James M Cleary, Scott Rodig, Benjamin Schlechter, Kimmie Ng, Stephanie K Dougan, Nora Horick, Glenn J Hanna, Andrew L Coveler, Anuj K Patel, Nadine J McCleary, Douglas A Rubinson, Jeffrey W Clark, Kent Mouw, Kathleen Pfaff, Thomas A Abrams, Matthew B Yurgelun, Eliezer M Van Allen, S Jennifer Wang, Leah H Biller, Harshabad Singh, Emma L Welsh, Brandon M Huffman, Lestat R Ali, Megan T Hoffman, Katherine A Metayer, Shayla Murray, Alexandra Bird, Jennifer A Chan, Wolfram Goessling, Jeffrey S Wisch, Brendan Reardon, Robert J Mayer, Catherine Del Vecchio Fitz, and Charlotte Kuperwasser
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Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Background Recent trials suggest that programmed cell death 1 (PD-1)-directed immunotherapy may be beneficial for some patients with anal squamous cell carcinoma and biomarkers predictive of response are greatly needed.Methods This multicenter phase II clinical trial (NCT02919969) enrolled patients with metastatic or locally advanced incurable anal squamous cell carcinoma (n=32). Patients received pembrolizumab 200 mg every 3 weeks. The primary endpoint of the trial was objective response rate (ORR). Exploratory objectives included analysis of potential predictive biomarkers including assessment of tumor-associated immune cell populations with multichannel immunofluorescence and analysis of circulating tumor tissue modified viral-human papillomavirus DNA (TTMV-HPV DNA) using serially collected blood samples. To characterize the clinical features of long-term responders, we combined data from our prospective trial with a retrospective cohort of patients with anal cancer treated with anti-PD-1 immunotherapy (n=18).Results In the phase II study, the ORR to pembrolizumab monotherapy was 9.4% and the median progression-free survival was 2.2 months. Despite the high level of HPV positivity observed with circulating TTMV-HPV DNA testing, the majority of patients had low levels of tumor-associated CD8+PD-1+ T cells on pretreatment biopsy. Patients who benefited from pembrolizumab had decreasing TTMV-HPV DNA scores and a complete responder’s TTMV-HPV DNA became undetectable. Long-term pembrolizumab responses were observed in one patient from the trial (5.3 years) and three patients (2.5, 6, and 8 years) from the retrospective cohort. Long-term responders had HPV-positive tumors, lacked liver metastases, and achieved a radiological complete response.Conclusions Pembrolizumab has durable efficacy in a rare subset of anal cancers. However, despite persistence of HPV infection, indicated by circulating HPV DNA, most advanced anal cancers have low numbers of tumor-associated CD8+PD-1+ T cells and are resistant to pembrolizumab.
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- 2024
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3. Metabolic requirement for GOT2 in pancreatic cancer depends on environmental context
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Samuel A Kerk, Lin Lin, Amy L Myers, Damien J Sutton, Anthony Andren, Peter Sajjakulnukit, Li Zhang, Yaqing Zhang, Jennifer A Jiménez, Barbara S Nelson, Brandon Chen, Anthony Robinson, Galloway Thurston, Samantha B Kemp, Nina G Steele, Megan T Hoffman, Hui-Ju Wen, Daniel Long, Sarah E Ackenhusen, Johanna Ramos, Xiaohua Gao, Zeribe C Nwosu, Stefanie Galban, Christopher J Halbrook, David B Lombard, David R Piwnica-Worms, Haoqiang Ying, Marina Pasca di Magliano, Howard C Crawford, Yatrik M Shah, and Costas A Lyssiotis
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tumor metabolism ,pancreatic cancer ,tumor microenvironment ,Medicine ,Science ,Biology (General) ,QH301-705.5 - Abstract
Mitochondrial glutamate-oxaloacetate transaminase 2 (GOT2) is part of the malate-aspartate shuttle, a mechanism by which cells transfer reducing equivalents from the cytosol to the mitochondria. GOT2 is a key component of mutant KRAS (KRAS*)-mediated rewiring of glutamine metabolism in pancreatic ductal adenocarcinoma (PDA). Here, we demonstrate that the loss of GOT2 disturbs redox homeostasis and halts proliferation of PDA cells in vitro. GOT2 knockdown (KD) in PDA cell lines in vitro induced NADH accumulation, decreased Asp and α-ketoglutarate (αKG) production, stalled glycolysis, disrupted the TCA cycle, and impaired proliferation. Oxidizing NADH through chemical or genetic means resolved the redox imbalance induced by GOT2 KD, permitting sustained proliferation. Despite a strong in vitro inhibitory phenotype, loss of GOT2 had no effect on tumor growth in xenograft PDA or autochthonous mouse models. We show that cancer-associated fibroblasts (CAFs), a major component of the pancreatic tumor microenvironment (TME), release the redox active metabolite pyruvate, and culturing GOT2 KD cells in CAF conditioned media (CM) rescued proliferation in vitro. Furthermore, blocking pyruvate import or pyruvate-to-lactate reduction prevented rescue of GOT2 KD in vitro by exogenous pyruvate or CAF CM. However, these interventions failed to sensitize xenografts to GOT2 KD in vivo, demonstrating the remarkable plasticity and differential metabolism deployed by PDA cells in vitro and in vivo. This emphasizes how the environmental context of distinct pre-clinical models impacts both cell-intrinsic metabolic rewiring and metabolic crosstalk with the TME.
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- 2022
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