Citations

Abstract OBJECTIVE: We sought to define the mechanisms by which purines regulate DNA repair and therapy response. METHODS: Phosphoproteomics was used to identify GTP-dependent (de)phosphorylation events after radiation (RT) and antibodies generated against novel sites. Animal models of glioblastoma (GBM) and normal tissues were used to assess DNA repair and treatment responses in vivo. RESULTS: Pharmacogenomic inhibition of GTP (but not ATP) synthesis sensitized GBM cells to RT by inhibiting the activity of non-homologous end joining, but not homologous recombination. We found a GTP-dependent RT-induced dephosphorylation event on Abl interactor 1 (Abi-1) serine 323 (S323) using phosphoproteomics. We generated a new antibody for p-Abi-1 (S323), validated its specificity, and confirmed that RT causes a GTP-dependent dephosphorylation of Abi-1 (S323). Knockout of Abi-1 slowed RT-induced double-strand break (DSB) repair, and this was rescued by re-expression of dephosphomimetic Abi-1 (S323A) but not phosphomimetic Abi-1 (S323D). Abi-1 canonically binds to G protein Rac1. Expression of constitutively active Rac1 promoted but dominant negative Rac1 blocked the dephosphorylation of Abi-1 (S323) and DSB repair. Knock-down or inhibition of protein phosphatase 5 reversed the GTP- and Rac1-mediated dephosphorylation of Abi-1 and DSB repair. In GBM PDX samples, p-Abi-1 (S323) levels negatively correlated with Rac1 activity and predicted favorable efficacy of genotoxic treatments. In orthotopic GBM mouse models, inhibiting Rac1 enhanced RT responses and suppressed Abi-1 (S323) dephosphorylation. Abi-1 knockout enhanced efficacy of genotoxic treatments and could be rescued by Abi-1 S323A (but not Abi-1 S323D) re-expression. This regulation is generalizable beyond brain cancer, as GTP supplementation promoted DNA repair and p-Abi1 (S323) dephosphorylation in non-malignant cells and protected mice from RT-mediated gastrointestinal injury and bleomycin-induced pulmonary fibrosis. CONCLUSION: The GTP-Rac1-PP5-Abi-1 signaling axis links metabolism and DNA repair. Disrupting this pathway can overcome cancer resistance to genotoxic therapy while augmenting it can mitigate genotoxic injury of normal tissues. Citation Format: Weihua Zhou, Zitong Zhao, Angelica Lin, John Yang, Jie Xu, Kari Wilder-Romans, Annabel Yang, Andrew J. Scott, Jing Li, Sumeet Solanki, Jennifer Speth, Natalie Walker, Ayesha U. Kothari, Yangyang Yao, Erik R. Peterson, Navyateja Korimerla, Christian K. Werner, Jessica Liang, Janna Jacobson, Sravya Palavalasa, Alexandra M Obrien, Ameer L Elaimy, Sean P. Ferris, Shuang G. Zhao, Jann N. Sarkaria, Balázs Győrffy, Shuqun Zhang, Wajd N. Al-Holou, Yoshie Umemura, Meredith A Morgan, Theodore S. Lawrence, Costas A. Lyssiotis, Marc Peters-Golden, Yatrik M. Shah, Daniel R. Wahl. GTP signaling links metabolism, DNA repair, and responses to genotoxic stress [abstract]. In: Proceedings of the AACR Special Conference on Brain Cancer; 2023 Oct 19-22; Minneapolis, Minnesota. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_1):Abstract nr A004.

There is extensive coverage in the existing literature on implant-associated lymphomas like anaplastic large-cell lymphoma, but breast implant-associated squamous cell carcinoma (BIA-SCC) has received limited scholarly attention since its first case in 1992. Thus, this study aims to conduct a qualitative synthesis focused on the underexplored association between breast implants and BIA-SCC. A systematic review was conducted utilizing the PubMed, Web of Science, and Cochrane databases to identify all currently reported cases of BIA-SCC. Additionally, a literature review was performed to identify potential biochemical mechanisms that could lead to BIA-SCC. Studies were vetted for quality using the NIH quality assessment tool. From an initial pool of 246 papers, 11 met the quality criteria for inclusion, examining a total of 14 patients aged between 40 and 81 years. BIA-SCC was found in a diverse range of implants, including those with smooth and textured surfaces, as well as those filled with saline and silicone. The condition notably manifested a proclivity for aggressive clinical progression, as evidenced by a mortality rate approximating 21.4% within a post-diagnostic interval of six months. Our literature review reveals that chronic inflammation, driven by various external factors such as pathogens and implants, can initiate carcinogenesis through epigenetic modifications and immune system alterations. This includes effects from exosomes and macrophage polarization, showcasing potential pathways for the pathogenesis of BIA-SCC. The study highlights the pressing need for further investigation into BIA-SCC, a subject hitherto inadequately addressed in the academic sphere. This necessitates the urgency for early screening and intervention to improve postoperative outcomes. While the review is confined by its reliance on case reports and series, it serves as a valuable reference for future research endeavors.

Abstract Anti-IgLON5 disease is a rare and likely underdiagnosed subtype of autoimmune encephalitis. The disease displays a heterogeneous phenotype that includes sleep, movement and bulbar-associated dysfunction. The presence of IgLON5-antibodies in CSF/serum, together with a strong association with HLA-DRB1*10:01∼DQB1*05:01, supports an autoimmune basis. In this study, a multicentric human leukocyte antigen (HLA) study of 87 anti-IgLON5 patients revealed a stronger association with HLA-DQ than HLA-DR. Specifically, we identified a predisposing rank-wise association with HLA-DQA1*01:05∼DQB1*05:01, HLA-DQA1*01:01∼DQB1*05:01 and HLA-DQA1*01:04∼DQB1*05:03 in 85% of patients. HLA sequences and binding cores for these three DQ heterodimers were similar, unlike those of linked DRB1 alleles, supporting a causal link to HLA-DQ. This association was further reflected in an increasingly later age of onset across each genotype group, with a delay of up to 11 years, while HLA-DQ-dosage dependent effects were also suggested by reduced risk in the presence of non-predisposing DQ1 alleles. The functional relevance of the observed HLA-DQ molecules was studied with competition binding assays. These proof-of-concept experiments revealed preferential binding of IgLON5 in a post-translationally modified, but not native, state to all three risk-associated HLA-DQ receptors. Further, a deamidated peptide from the Ig2-domain of IgLON5 activated T cells in two patients, compared with one control carrying HLA-DQA1*01:05∼DQB1*05:01. Taken together, these data support a HLA-DQ-mediated T-cell response to IgLON5 as a potentially key step in the initiation of autoimmunity in this disease.

Abstract Background: Mechanical thrombectomy (MT) has revolutionized the treatment of acute ischemic stroke (AIS) due to large vessel occlusion (LVO), but its efficacy and safety in medium vessel occlusion (MeVO) remain less explored. This multicenter, retrospective study aims to investigate the incidence and clinical outcomes of vessel perforations (confirmed by extravasation during an angiographic series) during MT for AIS caused by MeVO. Methods: Data were collected from 37 academic centers across North America, Asia, and Europe between September 2017 and July 2021. A total of 1373 AIS patients with MeVO underwent MT. Baseline characteristics, procedural details, and clinical outcomes were analyzed. Results: The incidence of vessel perforation was 4.8% (66/1373). Notably, our analysis indicates variations in perforation rates across different arterial segments: 8.9% in M3 segments, 4.3% in M2 segments, and 8.3% in A2 segments (p = 0.612). Patients with perforation had significantly worse outcomes, with lower rates of favorable angiographic outcomes (TICI 2c-3: 23% vs 58.9%, p < 0.001; TICI 2b-3: 56.5% vs 88.3%, p < 0.001). Functional outcomes were also worse in the perforation group (mRS 0–1 at 3 months: 22.7% vs 36.6%, p = 0.031; mRS 0–2 at 3 months: 28.8% vs 53.9%, p < 0.001). Mortality was higher in the perforation group (30.3% vs 16.8%, p = 0.008). Conclusion: This study reveals that while the occurrence of vessel perforation in MT for AIS due to MeVO is relatively rare, it is associated with poor functional outcomes and higher mortality. The findings highlight the need for increased caution and specialized training in performing MT for MeVO. Further prospective research is required for risk mitigation strategies.

This case-control study examines the incidence and risks of myeloid neoplasms in adults treated for B-cell lymphoproliferative disorders or multiple myeloma.

Abstract Accumulating evidence suggests that changes in the tumor microenvironment caused by radiotherapy are closely related to the recurrence of glioma. However, the mechanisms by which such radiation‐induced changes are involved in tumor regrowth have not yet been fully investigated. In the present study, how cranial irradiation‐induced senescence in non‐neoplastic brain cells contributes to glioma progression is explored. It is observed that senescent brain cells facilitated tumor regrowth by enhancing the peripheral recruitment of myeloid inflammatory cells in glioblastoma. Further, it is identified that astrocytes are one of the most susceptible senescent populations and that they promoted chemokine secretion in glioma cells via the senescence‐associated secretory phenotype. By using senolytic agents after radiotherapy to eliminate these senescent cells substantially prolonged survival time in preclinical models. The findings suggest the tumor‐promoting role of senescent astrocytes in the irradiated glioma microenvironment and emphasize the translational relevance of senolytic agents for enhancing the efficacy of radiotherapy in gliomas.

Introduction: Collateral cerebrovasculature is important for the survival of penumbral tissue in patients with large vessel occlusive (LVO) stroke, and adequate collateralization is associated with favorable outcomes. The presence of cerebral microbleeds (CMB) have been implicated in vessel wall remodeling and impaired vasoreactivity. We investigated whether the presence of deep and/or lobar CMB predicts poor collateral recruitment in patients with LVO stroke who underwent thrombectomy (MT). Methods: We performed a retrospective, single-center study of adults who presented with LVO stroke and had MT between January 2012-June 2020. CT angiography of head prior to MT was used to assess collateral status with poor status defined as ≤50% filling and good status as >50% filling. CMBs were assessed using T2*-weighted gradient echo or susceptibility weighted magnetic resonance images. Location of CMB was further characterized as deep vs. lobar using consensus definitions. Poor stroke outcome was defined as modified Rankin Scale (mRS) ≥3 at 90 days. Multivariable logistic regressions were performed to evaluate the associations between CMB, CMB types (lobar, deep, lobar+deep) and poor collaterals after adjusting for vascular risk factors. Results: Consecutive 151 subjects were included (mean age 68±15 years, 47% women), with a median NIHSS of 18. CMB were identified in 57 subjects (37.4%). Of these, 20.5% had lobar CMB, 5.3% had deep CMB and 11.9% had combined lobar & deep CMB. Patients with CMB had higher odds of having poor collaterals compared to those without CMB (OR 1.56, 95% CI 1.09-2.23, P=0.015). The association of CMB with poor collaterals was strongest in patients with combined lobar & deep CMB (OR 4.78, 95% CI 1.43-15.93, P=0.011), compared with those with exclusively deep CMB (OR 2.78, 95% CI 0.44-17.62, P=0.278) or lobar CMB (OR 0.52, 95% CI 0.19-1.38, P=0.188). Patients with poor collaterals were more likely to have poor outcome compared with those with good collaterals (48.4% vs. 31.0%, P=0.03). Conclusion: Cerebral microbleeds are independently associated with poor collateral recruitment when adjusted for traditional vascular risk factors. Further study is warranted to elucidate the differential effects of CMB types on collateral recruitment.

Background and Objectives: It is unclear whether induced hypertension in acute ischemic stroke (AIS) may improve long-term outcomes. We conducted a systematic review and meta-analysis to compare the safety and efficacy of induced hypertension vs standard medical care in patients presenting with acute ischemic stroke within 72 hours of symptom onset. Methods: Two reviewers systematically searched PubMed using the prespecified terms “induced hypertension” or “blood pressure augmentation” plus “ischemic stroke” for clinical trials that reported functional independence (mRS 0-2) at 90 days. The safety outcome was symptomatic intracranial hemorrhage (sICH). Pooled odds ratio (OR) and 95% CI across trials were synthesized using fixed-effect model based on Mantel-Haenszel methods. Forest plots were constructed. Results: Three clinical trials with 270 AIS patients treated with induced hypertension (n=126) or standard medical care (n= 144) were included. Mean age was 66.6 years, 35.2% were women, and the mean initial NIHSS was 7.5. The rate of functional independence at 90 days was higher in patients treated with induced hypertension (70.6%) versus control (54.9%) (OR 1.88; 95% CI 1.13-3.11; p=0.01). sICH did not differ between patients treated with induced hypertension (<1%) versus control (<1%) (OR 1.03; 95% CI 0.14-7.45; p=0.98). Discussion: Among patients presenting with acute ischemic stroke with 72 hours of symptoms onset, induced hypertension resulted in better functional outcome at 90 days than standard medical care and did not increase risk of sICH. Large RCTs to test this observation are ongoing and needed to guide clinical practice.

INTRODUCTION: This post hoc analysis evaluated the efficacy of tenapanor on abdominal symptoms in patients with irritable bowel syndrome with constipation. Abdominal symptoms assessed included pain, discomfort, bloating, cramping, and fullness. METHODS: The abdominal symptom data were pooled from 3 randomized controlled trials (NCT01923428, T3MPO-1 [NCT02621892], and T3MPO-2 [NCT02686138]). Weekly scores were calculated for each abdominal symptom, and the Abdominal Score (AS) was derived as the average of weekly scores for abdominal pain, discomfort, and bloating. The overall change from baseline during the 12 weeks was assessed for each symptom weekly score and the AS. The AS 6/12-week and 9/12-week response rates (AS improvement of ≥2 points for ≥6/12- or ≥9/12-week) were also evaluated. The association of weekly AS response status (reduction of ≥30%) with weekly complete spontaneous bowel movement (CSBM) status (=0 and >0) was assessed. RESULTS: Among 1,372 patients (684 tenapanor [50 mg twice a day] and 688 placebo), the least squares mean change from baseline in AS was −2.66 for tenapanor vs −2.09 for placebo ( P < 0.0001). The 6/12-week AS response rate was 44.4% for tenapanor vs 32.4% for placebo ( P < 0.0001), and for 9/12-week AS, 30.6% for tenapanor vs 20.5% for placebo ( P < 0.0001). A significant association between weekly CSBM status and weekly AS response status was observed each week ( P < 0.0001), with a greater proportion achieving an AS reduction in patients with >0 CSBMs in a week. DISCUSSION: Tenapanor significantly reduced abdominal symptoms in patients with irritable bowel syndrome with constipation, particularly pain, discomfort, and bloating measured by AS, compared with placebo.

TPS354 Background: Carriers of germline pathogenic variants or mutations in BRCA2 and BRCA1 (referred to here as gBRCA1/2m) are enriched in metastatic prostate cancer (PrCa), and now have FDA-approved options for PARP inhibitors in late-stage disease. The NCCN guidelines recommends germline genetic testing for PrCa patients with metastatic, node positive and high risk localized prostate cancer. Prior studies have shown that gBRCA1/2m carriers with PrCa are more likely to have high-risk disease (6,7) and to develop lethal disease even after curative intent treatment (8,9). In other gBRCA1/2m-related cancers (breast, ovarian and pancreas), platinum-based regimens are part of neoadjuvant and front-line metastatic therapy options. Carboplatin is a well-tolerated, widely available and inexpensive DNA-damaging alkylating agent that is familiar to oncologists. The study hypothesis is that 4 cycles of neoadjuvant carboplatin, followed by radical prostatectomy for patients with localized high/very high risk PrCa and g BRCA1/2m will result in a meaningful pathologic complete response (pCR) rate. Methods: S2210 is a single-arm, open label study of 12 wks neoadjuvant carboplatin (4 cycles of AUC 5 every 21 days), followed by radical prostatectomy. Key eligibility criteria include people with high/very high-risk disease: cT3a or Grade Group 4-5 PrCa and/or PSA>20 ng/mL, have no evidence of distant metastases by conventional imaging (PSMA-PET-detected mets permitted if conventional imaging is negative and surgeon deems PSMA-detected sites resectable), who are candidates for radical prostatectomy and carboplatin, and have documented evidence of gBRCA1/2m through testing in a CLIA-certified lab. ADT prior to registration is permitted but must be discontinued on study. The study hypothesis is that the study treatment will result in ³30% rate of pathologic complete response (pCR, primary endpoint). A two-stage design will be used such that if ³1 of first 20 eligible patients achieves pCR, 20 further evaluable patients will be enrolled. This design has a significance level of 4.7%, and a power of 99%. Secondary endpoints include biochemical recurrence-free (at 2-, 3-, 5-yrs), metastasis-free and overall survival. Translational/correlative studies include analysis of 2nd allele inactivation in tumor, HRD signature, and ctDNA signature for monitoring of recurrence. S2210 was activated in August 2023. Clinical trial information: NCT05806515 .