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The rapid identification of protein-protein interactions has been significantly enabled by mass spectrometry (MS) proteomics-based methods, including affinity purification-MS, crosslinking-MS, and proximity-labeling proteomics. While these methods can reveal networks of interacting proteins, they cannot reveal how specific protein-protein interactions alter protein function or cell signaling. For instance, when two proteins interact, there can be emergent signaling processes driven purely by the individual activities of those proteins being co-localized. Alternatively, protein-protein interactions can allosterically regulate function, enhancing or suppressing activity in response to binding. In this work, we investigate the interaction between the tyrosine phosphatase PTP1B and the adaptor protein Grb2, which have been annotated as binding partners in a number of proteomics studies. This interaction has been postulated to co-localize PTP1B with its substrate IRS-1 by forming a ternary complex, thereby enhancing the dephosphorylation of IRS-1 to suppress insulin signaling. Here, we report that Grb2 binding to PTP1B also allosterically enhances PTP1B catalytic activity. We show that this interaction is dependent on the proline-rich region of PTP1B, which interacts with the C-terminal SH3 domain of Grb2. Using NMR spectroscopy and hydrogen-deuterium exchange mass spectrometry (HDX-MS) we show that Grb2 binding alters PTP1B structure and/or dynamics. Finally, we use MS proteomics to identify other interactors of the PTP1B proline-rich region that may also regulate PTP1B function similarly to Grb2. This work presents one of the first examples of a protein allosterically regulating the enzymatic activity of PTP1B and lays the foundation for discovering new mechanisms of PTP1B regulation in cell signaling., (© 2024 The Protein Society.)

The rapid identification of protein-protein interactions has been significantly enabled by mass spectrometry (MS) proteomics-based methods, including affinity purification-MS, crosslinking-MS, and proximity-labeling proteomics. While these methods can reveal networks of interacting proteins, they cannot reveal how specific protein-protein interactions alter protein function or cell signaling. For instance, when two proteins interact, there can be emergent signaling processes driven purely by the individual activities of those proteins being co-localized. Alternatively, protein-protein interactions can allosterically regulate function, enhancing or suppressing activity in response to binding. In this work, we investigate the interaction between the tyrosine phosphatase PTP1B and the adaptor protein Grb2, which have been annotated as binding partners in a number of proteomics studies. This interaction has been postulated to co-localize PTP1B with its substrate IRS-1 by forming a ternary complex, thereby enhancing the dephosphorylation of IRS-1 to suppress insulin signaling. Here, we report that Grb2 binding to PTP1B also allosterically enhances PTP1B catalytic activity. We show that this interaction is dependent on the proline-rich region of PTP1B, which interacts with the C-terminal SH3 domain of Grb2. Using NMR spectroscopy and hydrogen-deuterium exchange mass spectrometry (HDX-MS) we show that Grb2 binding alters PTP1B structure and/or dynamics. Finally, we use MS proteomics to identify other interactors of the PTP1B proline-rich region that may also regulate PTP1B function similarly to Grb2. This work presents one of the first examples of a protein allosterically regulating the enzymatic activity of PTP1B and lays the foundation for discovering new mechanisms of PTP1B regulation in cell signaling., Competing Interests: Competing Interests The authors declare no competing interests.

Background and Objective: Belzutifan, a hypoxia-inducible factor 2 alpha inhibitor, was approved initially for patients with von Hippel-Lindau disease and more recently for sporadic, metastatic clear cell renal cell carcinoma (ccRCC) based on the results of LITESPARK-005. There is a paucity of data regarding real-world experience with belzutifan in patients with sporadic, metastatic ccRCC. This study aims to describe clinical outcomes with belzutifan in patients with sporadic, metastatic ccRCC., Methods: A retrospective study of 22 patients who received belzutifan at MD Anderson Cancer Center prior to the Food and Drug Administration approval was conducted. Progression-free survival (PFS) and objective response rate (ORR) were assessed by a blinded radiologist using Response Evaluation Criteria In Solid Tumors (RECIST) version 1.1. PFS and overall survival (OS) were measured from belzutifan initiation., Key Findings and Limitations: The median follow-up time was 14.9 mo. Most patients had International Metastatic RCC Database Consortium intermediate-risk disease, more than three metastatic sites, and a median of five prior lines of treatment at initiation of belzutifan; all patients received prior immune checkpoint therapy (ICT) and vascular endothelial growth factor receptor tyrosine kinase inhibitors (VEGFR-TKIs). The median PFS was 8.51 mo (95% confidence interval [CI] 0-18.4) and ORR was 36.4%. The median OS was 14.72 mo (95% CI 7.34-22.10). Of 22 patients, four (18.2%) patients required dose reductions and three (13.6%) patients discontinued belzutifan because of adverse drug events (ADEs). The most common ADEs were anemia (77.3%; 17/22) and hypoxia (36.4%; 8/22). There were no treatment-related deaths., Conclusions and Clinical Implications: In a heavily pretreated cohort of patients with sporadic, metastatic ccRCC, belzutifan had meaningful clinical activity and was well tolerated. These real-world results add to the results of LITESPARK-005 and support the use of belzutifan after progression on ICT and VEGFR-TKIs., Patient Summary: Belzutifan is a new medicine used to treat a type of clear cell kidney cancer that has spread to other parts of the body (metastasized). A study at MD Anderson Cancer Center followed 22 patients who were treated with belzutifan, and found that it worked to control the cancer for almost 9 mo and caused the cancer to shrink in 36% of patients. This study confirms that belzutifan can be effective and safe, even after other treatments have not worked., (Copyright © 2024 European Association of Urology. Published by Elsevier B.V. All rights reserved.)

Background: Tivozanib has been approved as a third-line or later therapy for advanced renal cell carcinoma based on the TIVO-3 trial, which was conducted before immune checkpoint therapies (ICT), cabozantinib, and lenvatinib/everolimus became incorporated in the current sequential treatment paradigm for advanced clear cell RCC (ccRCC)., Methods: We performed a retrospective study of patients with advanced ccRCC treated with tivozanib at MD Anderson Cancer Center during 6/2021-7/2023. A blinded radiologist assessed tumor response by RECIST v1.1. We assessed overall response rate (ORR), clinical benefit rate (CBR) [percentage of all treated patients who achieved radiologic response or stable disease (SD) for ≥ 6 months], progression-free survival (PFS), overall survival (OS), and safety., Results: Of 30 analyzed patients, 23% had performance status ≥ 2; 47% had International Metastatic RCC Database Consortium (IMDC) poor-risk disease. Median number of prior therapies was 4 (range 1-8). All patients received prior ICT, 87% cabozantinib and 60% lenvatinib ± everolimus. Of 26 evaluable patients, 2 patients had confirmed partial response (ORR 7.7%); 5 patients had SD for ≥ 6 months (CBR 23.3%). Median PFS was 3.8 months (range 0.7-13.9); median OS was 14.1 months (range 0.3-28.5). Fifteen patients (50%) had ≥ 1 treatment-related adverse event (TRAE). There were 6 grade ≥ 3 TRAEs [hypertension, congestive heart failure (3), mucositis, and GI perforation (grade 5)]., Conclusions: In this cohort of heavily pretreated patients with advanced ccRCC, tivozanib yielded a modest clinical benefit in a minority of patients who received prior ICT, cabozantinib, and lenvatinib ± everolimus. TRAEs were consistent with previously published reports., (© The Author(s) 2024. Published by Oxford University Press.)

Germ cell tumor of the testis (GCT) is a curable cancer even when it is widely metastatic; however, outcomes can differ based on tumor histology. Chemo-resistance in certain phenotypes, such as teratoma and yolk sac tumor, contributes to poor clinical outcomes in some patients with GCT. Despite this resistance to S-YSTemic therapy, many of these tumor subtypes remain amenable to surgical resection and possible cure. In this study, we report on a series of seven patients highlighting two chemo-resistant subtypes of nonseminomatous germ cell tumor (NSGCT), sarcomatoid yolk sac tumor (S-YST), and epithelioid trophoblastic tumor (ETT) for which early resection rather than additional salvage chemotherapy or high-dose intense chemotherapy might provide a superior clinical outcome and enhance cure rate.

Photoactivated chemotherapy (PACT) is a promising cancer treatment modality that kills cancer cells via photochemical uncaging of a cytotoxic drug. Most ruthenium-based photocages used for PACT are activated with blue or green light, which penetrates sub-optimally into tumor tissues. Here, we report amide functionalization as a tool to fine-tune the toxicity and excited states of a terpyridine-based ruthenium photocage. Due to conjugation of the amide group with the terpyridine π system in the excited state, the absorption of red light (630 nm) increased 8-fold, and the photosubstitution rate rose 5-fold. In vitro, red light activation triggered inhibition of tubulin polymerization, which led to apoptotic cell death both in normoxic (21 % O 2 ) and hypoxic (1 % O 2 ) cancer cells. In vivo, red light irradiation of tumor-bearing mice demonstrated significant tumor volume reduction (45 %) with improved biosafety, thereby demonstrating the clinical potential of this compound., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

State-of-the-art methods in photoproximity labeling center on the targeted generation and capture of short-lived reactive intermediates to provide a snapshot of local protein environments. Diazirines are the current gold standard for high-resolution proximity labeling, generating short-lived aryl(trifluoromethyl) carbenes. Here, we present a method to access aryl(trifluoromethyl) carbenes from a stable diazo source via tissue-penetrable, deep red to near-infrared light (600-800 nm). The operative mechanism of this activation involves Dexter energy transfer from photoexcited osmium(II) photocatalysts to the diazo, thus revealing an aryl(trifluoromethyl) carbene. The labeling preferences of the diazo probe with amino acids are studied, showing high reactivity toward heteroatom-H bonds. Upon the synthesis of a biotinylated diazo probe, labeling studies are conducted on native proteins as well as proteins conjugated to the Os photocatalyst. Finally, we demonstrate that the conjugation of a protein inhibitor to the photocatalyst also enables selective protein labeling in the presence of spectator proteins and achieves specific labeling of a membrane protein on the surface of mammalian cells via a two-antibody photocatalytic system.

Previously, we developed an innovative high-content screening (HCS) approach to quantify neuroblastoma cell differentiation based on neurite outgrowth, a morphological differentiation marker of neuroblastoma cells. Here, we report the utilization of this platform to identify 1-methyl-5-(ethylsulfonyl)-1H-tetrazole (3a) as a new neuroblastoma differentiation agent using the ChemBridge Diverset TM commercial synthetic small molecule compound library. We show that this activity can be extended to a group of analogues, which can be accessed via a short two-step synthetic sequence. A new analogue, 5-(allylsulfonyl)-1-methyl-1H-tetrazole (3c) was identified in this synthetic effort as a compound that has even more pronounced differentiation and cytotoxic activities than the original hit compound 3a., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Objectives: Immune checkpoint inhibitor immunotherapy (IO) is revolutionizing cancer care but can lead to significant toxicity. This study seeks to describe potential risk factors for immune-related adverse events (irAEs) specifically among older adults., Materials and Methods: This was a retrospective study at a single academic comprehensive cancer center based on chart review data abstracted by physicians. For patients aged ≥70 years, frequency, type, and grade of irAEs and their association with baseline patient demographics, comorbidities, mobility, and functional status were characterized using bivariate analysis. Based on those results, multivariable logistic regressions were constructed to model the association between these characteristics with any grade and grade 3 or higher irAEs., Results: Data were analyzed for 238 patients aged ≥70 years who received IO for mostly (≥90%) advanced cancer between 2011 and 2018. Thirty-nine percent of older adults experienced an irAE and 13% experienced one that was grade 3 or higher. In the multivariable analysis, depression was associated with an increased incidence of any grade irAE, while decreased life-space mobility was associated with an increased incidence of grade ≥3 irAEs., Conclusion: Most characteristics of special interest among older adults, include fall risk, weight loss, cognitive limitations, and hearing loss, were not associated with irAEs in our study. However, decreased life-space mobility and depression are potential risk factors for IO toxicity among older adults with advanced cancer. Interventions designed to evaluate and mitigate modifiable risk factors for treatment-related toxicity are needed, and the results of this study may be useful for guiding those efforts., (© The Author(s) 2023. Published by Oxford University Press.)

Background and Objectives: Medical comorbidities (MC) are highly prevalent among patients with cancer and predict worse outcomes for traditional therapies. This association is poorly understood for checkpoint inhibitor immunotherapy (IO). We aimed to explore the relationship between common MC including cardiovascular disease (CVD), immune-related adverse events (irAEs), and overall survival (OS) among patients receiving IO for advanced cancer., Methods: This is a retrospective cohort study of 671 patients with any cancer who received IO at our institution from 2011 to 2018. Clinical data were abstracted via chart review and query of ICD-10 codes and used to calculate modified Charlson comorbidity index (mCCI) scores. The primary outcomes were the association of individual MC with irAEs and OS using bivariate and multivariable analyses. Secondary outcomes included association of mCCI score with irAEs and OS., Results: Among 671 patients, 62.1% had a mCCI score ≥ 1. No individual MC were associated with irAEs or OS. Increased CCI score was associated with decreased OS (p < 0.01) but not with irAEs. Grade ≥ 3 irAEs were associated with increased OS among patients without CVD (HR 0.37 [95% CI: 0.25, 0.55], p < 0.01), but not among patients with CVD., Conclusions: No specific MC predicted risk of irAEs or OS for patients receiving IO. Increased CCI score did not predict risk of irAEs but was associated with shorter OS. This suggests IO is safe for patients with MC, but MC may limit survival benefits of IO. CVD may predict shorter OS in patients with irAEs and should be evaluated among patients receiving IO., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Protein tyrosine phosphatases (PTPs) are an important class of enzymes that modulate essential cellular processes through protein dephosphorylation and are dysregulated in various disease states. There is demand for new compounds that target the active sites of these enzymes, for use as chemical tools to dissect their biological roles or as leads for the development of new therapeutics. In this study, we explore an array of electrophiles and fragment scaffolds to investigate the required chemical parameters for covalent inhibition of tyrosine phosphatases. Our analysis juxtaposes the intrinsic electrophilicity of these compounds with their potency against several classical PTPs, revealing chemotypes that inhibit tyrosine phosphatases while minimizing excessive, potentially non-specific reactivity. We also assess sequence divergence at key residues in PTPs to explain their differential susceptibility to covalent inhibition. We anticipate that our study will inspire new strategies to develop covalent probes and inhibitors for tyrosine phosphatases., (© 2023 Wiley-VCH GmbH.)

Abstract: Antibody-drug conjugates are becoming increasingly important in the treatment of many cancer types. The 3 main structural components-antibody, linker, and payload-each contribute to the toxicity profiles of these drugs. In addition to cytopenias and gastrointestinal adverse effects attributed to the chemotherapy payloads, each drug has specific toxicities that are not commonly described in oncology. Ocular, pulmonary, dermatologic, and neurologic toxicities are particularly nuanced. This review provides a framework for clinicians to analyze current and future antibody-drug conjugates and a description of the unique monitoring, preventive, and supportive care measures for these agents., Competing Interests: Conflicts of Interest and Source of Funding: M.T.C. reports consulting/advisory roles for Eisai, EMD Serono, Pfizer, Genentech, AstraZeneca, SeaGen, Exelixis, Astellas, and AXDev. He reports trials with grant support from Exelixis, Pfizer/EMD Serono, Janssen, ApricityHeath, Aravive, and AstraZeneca. He reports the following nonbranded educational programs: BMS, Roche, Merck, and Pfizer/EMD Serono. For A.C.J., none were declared., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Objectives: Despite growing evidence that checkpoint inhibitor immunotherapy (IO) toxicity is associated with improved treatment response, the relationship between immune-related adverse events (irAEs) and overall survival (OS) among older adults [age ≥ 70 years (y)] remains unknown. The study goal was to determine differences in OS based on age and ≥ grade 3 (G3) irAEs., Materials and Methods: This was a retrospective cohort study of 673 patients with advanced cancer. Patients who received ≥1 dose of IO at our institution from 2011 to 2018 were eligible. The primary outcome was OS from the start of first line of IO treatment, compared between four patient groups stratified by age and ≥ G3 irAEs with adjustment for patient characteristics using a Cox proportional hazards model., Results and Conclusion: Among all 673 patients, 35.4% were ≥ 70y, 39.8% had melanoma, and 45.6% received single-agent nivolumab. Incidence and types of ≥G3 irAEs did not differ by age. Median OS was significantly longer for all patients with ≥G3 irAEs (unadjusted 21.7 vs. 11.9 months, P = 0.007). There was no difference in OS among patients ≥70y with ≥G3 irAEs (HR 0.94, 95% CI 0.61-1.47, P = 0.79) in the multivariable analysis. Patients <70y with ≥G3 irAEs had significantly increased OS (HR 0.33, 95% CI 0.21-0.52, P < 0.001). Younger patients, but not older adults, with high-grade irAEs experience strong survival benefit. This difference may be due to the toll of irAEs themselves or the effects of treatments for irAEs, such as corticosteroids. Factors impacting OS of older adults after irAEs must be determined and optimized., Competing Interests: Declaration of Competing Interest Dr. Rosko reports receiving institution-directed research funding from Regeneron, Millennium, and Janssen. Dr. Carbone reports receiving a research grant from Bristol-Myers Squibb and consultant work for Abbvie, Adaptimmune, Agenus, Amgen, Ariad, AstraZeneca, Biocept, Boehringer Ingelheim, Bristol Myers-Squibb (BMS), Celgene, Clovis, Daiichi Sankyo, Inc. (DSI), EMD Serono, Foundation Medicine, GenePlus, Genentech/Roche, Glaxo-Smith-Kline, Gloria BioScience, Gritstone, Guardant Health, Helsinn, Humana, Incyte, Inivata, Inovio, Janssen, Kyowa Kirin, Loxo Oncology, Merck, MSD, Nexus Oncology, Novartis, Palobiofarma, Pfizer, prIME Oncology, Stemcentrx, Takeda Oncology, and Teva. Dr. Owen reports receiving institution-directed research funding from Bristol-Myers Squibb, Merck, Genentech, Palbiofarma, and Abbvie; he reports consultant work for theMednet and Astrazeneca., (Copyright © 2021 Elsevier Inc. All rights reserved.)