Split-Course Adaptive Radioimmunotherapy for Oligometastatic Non-Small Cell Lung Cancer (SiCARIO): A Case Report.

Current treatment paradigms for oligometastatic non-small cell lung cancer (NSCLC) utilize systemic chemotherapy alone or in combination with immune checkpoint inhibitors (ICIs). The addition of ICIs in NSCLC has led to significant improvements in survival; however, recurrence remains common. New methods are needed to enhance anti-tumor immune responses and improve patient outcomes. Here, we present the first case of utilization of the Ethos OART platform to deliver multi-site pulsed hypofractionated radiotherapy in a patient with oligometastatic disease on the single arm prospective clinical trial SiCARIO (Split-Course Adaptive Radioimmunotherapy in Oligometastatic NSCLC, NCT05501665). A 67-year-old man with stage IV NSCLC with metastases to bilateral adrenal glands, retroperitoneum, and mesentery was prescribed treatment of 40 Gy in 5 fractions on SiCARIO in combination with SOC chemoimmunotherapy. A multi-target single isocenter approach was utilized to treat nine distinct targets in five total isocenters. Treatment plans were generated using an isotopic approach prioritizing organ at risk (OAR) constraints with the goal of minimum coverage of at least 30 Gy in 5 fractions. CBCT was acquired with each fraction to generate new targets and OAR contours based on anatomic changes with the patient on the treatment table. A comparison of an adapted plan to a base plan was performed online with a selection of superior plans based on target coverage and OAR constraints. The adapted plan was deemed superior for all but 1 fraction of a single isocenter for this patient. The discussion will focus primarily on the bilateral adrenal isocenter, where bulk tumor shrinkage of greater than 80% was observed in this patient with corresponding significant dosimetric benefits. This case demonstrates a potential clinical benefit of OART in multi-metastasis RT. Further data is needed to confirm the safety and efficacy of this approach. Enrollment is ongoing.

Treatment-Refractory Scleredema Diabeticorum Managed With Re-irradiation Using Volumetric Modulated Arc Therapy.

Scleredema diabeticorum is a rare connective tissue complication of diabetes, most typically observed in adults with longstanding type 2 diabetes. Patients develop reticular dermis thickening with a peau d'orange appearance at the upper back and neck that occasionally extends over the deltoids and lower back. While considered a benign disorder, it may signify more significant diabetes and can be functionally and cosmetically impairing with insidious onset, few to no effective treatments, and low spontaneous remission potential. Treatment options are limited; however, radiation therapy has shown clinical benefit in severe cases. Common treatment utilizes 20-24 Gy in 10-12 fractions with retreatment sometimes required for adequate symptom control. Here, we present a case of extensive, treatment-refractory diabetic scleredema status post six separate prior treatments with electron radiotherapy with clinical progression of disease, including involvement of anterior neck limiting jaw and neck range of motion. Volumetric modulated arc therapy (VMAT) was utilized to cover all areas of extensive disease and to treat deeper tissues, which we postulated may decrease skin and underlying tissue tightness and provide clinically meaningful improvements in range of motion. A 57-year-old female with longstanding type 1 diabetes and a six-year history of biopsy-confirmed scleredema presented with treatment-refractory disease in 2022 of the upper back, bilateral upper arms, and neck. Her disease distribution included 270 degrees around her neck, making electron therapy unviable. She had previously undergone multiple treatments, including six separate electron radiotherapy treatment courses to her back, shoulders, and posterior neck between 2016 and 2020 (ranging from 12 Gy in 6 fractions to 24 Gy in 12 fractions for each course), psoralen UV-A therapy, physiotherapy, methotrexate, and percussive therapy. To address the disease extending anteriorly around her neck and below her jaw, as well as the posterior involvement of her shoulders, back, and neck, a more extensive VMAT re-irradiation plan was developed. The plan successfully delivered 20 Gy in 10 fractions to areas of clinically evident disease. Toxicity was evaluated using the Common Terminology Criteria for Adverse Events (CTCAE) scoring system at the time of treatment and at the three-month follow-up. Functional improvement, patient satisfaction, skin texture, and induration were assessed during treatment and at her follow-up visit. Following VMAT re-irradiation, the patient denied scorable toxicity and noted the return of mobility in her neck and jaw. We concluded that VMAT-based re-irradiation is a safe and effective option for patients with treatment-refractory scleredema diabeticorum that is non-responsive or not amenable to electron therapy.

Consolidation ALK Tyrosine Kinase Inhibitors Versus Durvalumab or Observation After Chemoradiation in Unresectable Stage III ALK-Positive NSCLC.

INTRODUCTION: Patients with advanced ALK-positive NSCLC typically have poor response to immunotherapy; the benefit of consolidation durvalumab in patients with unresectable stage III ALK-positive NSCLC remains unclear. Herein, we compare the efficacy and safety of consolidation ALK tyrosine kinase inhibitor (TKI) versus durvalumab or observation after concurrent chemoradiation. METHODS: We conducted a retrospective study using a multicenter study of 17 institutions globally. Patients with unresectable stage III ALK-positive NSCLC treated between 2015 and 2022 were included. Patients received ALK TKI, durvalumab, or observation after concurrent chemoradiation. Real-world progression-free survival (rwPFS) and overall survival (OS) were estimated using Kaplan-Meier method. Treatment-related adverse events (trAEs) were classified by Common Terminology Criteria for Adverse Events version 5.0. Outcomes were assessed by multivariable Cox regression analysis. RESULTS: A total of 67 patients were included, of whom 39 (58%) were female. Median age was 57 (interquartile range: 49-67) years. Furthermore, 15 received consolidation ALK TKI, 30 received durvalumab, and 22 underwent observation. Baseline characteristics were similar across the three groups other than differences in race. After adjusting for stage, age, and nodal status, median rwPFS was significantly longer for ALK TKI (rwPFS not reached, 95% confidence interval [CI]: 22.7- not reached) versus durvalumab (11.3 mo, 95% CI: 8.9-18.5, hazard ratio [HR] = 0.12, 95% CI: 0.026-0.5, p-adjusted [p-adj] = 0.006) or observation (7.2 mo, 95% CI: 3.4-10.6, HR = 0.04, 95% CI: 0.009-0.2, p-adj < 0.0001). Durvalumab significantly improved median rwPFS compared with observation (HR = 0.37, 95% CI: 0.19-0.71, p-adj = 0.002). Median OS in the ALK TKI and durvalumab cohorts was significantly improved compared with patients on observation (ALK TKI-observation: p = 0.04; durvalumab-observation: p = 0.03). TrAE of any grade occurred in eight (53%) and 11 (37%) patients treated with ALK TKI and durvalumab, respectively. Grade greater than or equal to three trAEs occurred in 27% (n = 4) of patients treated with ALK TKI and 6.7% of patients treated with durvalumab. CONCLUSIONS: Patients with ALK-positive NSCLC experience significantly improved rwPFS when treated with consolidation ALK TKI therapy, surpassing outcomes found with either durvalumab or observation. Although both ALK TKI therapy and durvalumab offer an extension in OS compared with observation alone, it seems that ALK TKI therapy is the superior choice, underscoring its pivotal role in enhancing patient survival.

Visual pathology reports for improved collaboration at multidisciplinary head and neck tumor board.

PURPOSE: Multidisciplinary tumor boards (TB) are the standard for discussing complex head and neck cancer cases. During TB, imaging and microscopic pathology is reviewed, but there is typically no visualization of the resected cancer. METHODS: A pilot study was conducted to investigate the utility of visual pathology reports at weekly TB for 10 consecutive weeks. Faculty-level participants completed a pre-survey and post-survey to assess understanding of resected cancer specimens. RESULTS: Providers (n = 25) across seven medical specialties completed pre-survey and post-survey. Following intervention, providers reported significant improvement in understanding of anatomic orientation of the specimen and sites of margin sampling (mean 47.4-96.1, p < 0.001), ability to locate the site of a positive margin (mean 69.5-91.1, p < 0.001), and confidence in treatment plans created (mean 69.5-89.2, p < 0.001) with the addition of visual pathology reports. CONCLUSIONS: Visual pathology reports improve provider understanding of resected cancer specimens at multidisciplinary TB.

Durvalumab After Chemoradiotherapy in Patients With Unresectable Stage III Non-Small Cell Lung Cancer.

Importance: The PACIFIC trial established consolidation durvalumab as the standard of care following chemoradiotherapy (CRT) for patients with unresectable stage III non-small cell lung cancer (NSCLC). Understanding its benefit in routine US clinical practice is critical. Objective: To report characteristics, treatment patterns, and outcomes of patients who did or did not receive durvalumab. Design, Setting, and Participants: Two prespecified cohorts were curated in this retrospective cohort study (SPOTLIGHT). Deidentified patient-level data from a US database (Flatiron Health) were analyzed. Patients had unresectable stage III NSCLC, were diagnosed on or after January 1, 2011, had 2 or more visits on or afterward, and received CRT. Data were analyzed from May 2021 to October 2023. Exposures: Patients started durvalumab after CRT (durvalumab cohort) or ended CRT without durvalumab (nondurvalumab cohort) by June 30, 2019, to allow 15 or more months of follow-up from CRT end. Main Outcomes and Measures: End points included progression-free survival (PFS), overall survival (OS), time to first subsequent therapy or death (TFST), and time to distant metastasis or death (TTDM). Results: The durvalumab cohort included 332 patients (median [IQR] age, 67.5 [60.8-74.0] years; 187 were male [56.3%], 27 were Black [8.7%], 33 were other races [10.7%], and 249 were White [80.6%]) and the nondurvalumab cohort included 137 patients (median (IQR) age, 70.0 [64.0-75.0] years; 89 [65.0%] were male, 11 [8.9%] were Black, 19 [15.4%] were other races, and 93 [75.6%] were White). Most patients had a smoking history (durvalumab, 316 patients [95.2%] and nondurvalumab, 132 patients [96.4%]) and Eastern Cooperative Oncology Group performance status 0 through 1 (durvalumab, 251 patients [90.9%] and nondurvalumab, 88 patients [81.5%]). Median (IQR) CRT duration was 1.6 (1.4-1.8) months for the durvalumab cohort and 1.5 (1.4-1.8) months for the nondurvalumab cohort. Median time to durvalumab discontinuation was 9.5 months (95% CI, 7.8-10.6 months). Median TFST and TTDM were not reached (NR) in the durvalumab cohort and 8.3 months (95% CI, 4.8-11.8 months) and 11.3 months (95% CI, 6.4-14.5 months), respectively, in the nondurvalumab cohort. Median PFS and OS were 17.5 months (95% CI, 13.6-24.8 months) and NR in the durvalumab cohort and 7.6 months (95% CI, 5.2-9.8 months) and 19.4 months (95% CI, 11.7-24.0 months) in the nondurvalumab cohort. In Cox regression analyses of patients who completed concurrent CRT without progression, durvalumab was associated with a lower risk of progression or death (hazard ratio [HR], 0.36; 95% CI, 0.26-0.51) and lower risk of death (HR, 0.27; 95% CI, 0.16-0.43), adjusted for prior platinum agent and patient characteristics. Conclusions and Relevance: In this cohort study, findings were consistent with PACIFIC, and durvalumab was associated with a lower risk of progression and/or death. Further investigation is warranted to explain why patients did not receive durvalumab after its approval.

Consolidation Osimertinib Versus Durvalumab Versus Observation After Concurrent Chemoradiation in Unresectable EGFR-Mutant NSCLC: A Multicenter Retrospective Cohort Study.

INTRODUCTION: Durvalumab improves survival when used as consolidation therapy after chemoradiation (CRT) in patients with stage III NSCLC. The optimal consolidation therapy for patients with EGFR-mutant (EGFRmut) stage III NSCLC remains unknown. METHODS: In this multi-institutional, international retrospective analysis across 24 institutions, we evaluated outcomes in patients with stage III EGFRmut NSCLC treated with concurrent CRT followed by consolidation therapy with osimertinib, durvalumab, or observation between 2015 and 2022. Kaplan-Meier method was used to estimate real-world progression-free survival (rwPFS, primary end point) and overall survival (secondary end point). Treatment-related adverse events (trAEs) during consolidation treatment were defined using Common Terminology Criteria for Adverse Events version 5.0. Multivariable Cox regression analysis was used. RESULTS: Of 136 patients with stage III EGFRmut NSCLC treated with definitive concurrent CRT, 56 received consolidation durvalumab, 33 received consolidation osimertinib, and 47 was on observation alone. Baseline characteristics were similar across the three cohorts. With a median follow-up of 46 months for the entire cohort, the median duration of treatment was not reached (NR) for osimertinib (interquartile range: NR-NR) and was 5.5 (interquartile range: 2.4-10.8) months with durvalumab. After adjusting for nodal status, stage III A/B/C, and age, patients treated with consolidation osimertinib had significantly longer 24-month rwPFS compared to those treated with durvalumab or in the observation cohorts (osimertinib: 86%, durvalumab: 30%, observation: 27%, p < 0.001 for both comparisons). There was no difference in rwPFS between the durvalumab and the observation cohorts. No significant difference in overall survival across the three cohorts was detected, likely due to the limited follow-up. Any-grade trAE occurred in 52% (2 [6.1%] grade ≥3) and 48% (10 [18%] grade ≥3) of patients treated with osimertinib and durvalumab, respectively. Of 45 patients who progressed on consolidation durvalumab, 37 (82%) subsequently received EGFR tyrosine kinase inhibitors. Of these, 14 (38%) patients developed trAEs including five patients with pneumonitis (14%; 2 [5.4%] grade ≥3) and five patients with diarrhea (14%; 1 [2.7%] grade ≥3). CONCLUSIONS: This study suggests that among patients with stage III unresectable NSCLC with a sensitizing EGFR mutation, consolidation osimertinib was associated with a significantly longer rwPFS compared to durvalumab or observation. No unanticipated safety signals were observed with consolidation osimertinib.

A Retrospective Cohort Study of Longitudinal Audiologic Assessment in Single and Fractionated Stereotactic Radiosurgery for Vestibular Schwannoma.

BACKGROUND: Fractionated stereotactic radiosurgery (SRS) for vestibular schwannomas (VS) has been theorized to allow for tumor control with higher rates of hearing preservation in selected patients with useful hearing. However, there is a paucity of literature with formal audiologic measures of hearing preservation to support the standard use of fractionated SRS in VS. We hypothesized that fractionation would diminish the amount of hearing damage. OBJECTIVE: To evaluate the relationship between audiologic performance and SRS fractionation scheme. METHODS: We performed an IRB-approved retrospective review of patients treated with 1, 3, or 5 fraction SRS for VS at our institution from 1998 to 2016. Pre- and post-SRS audiograms with speech awareness threshold (SAT) in treated and contralateral ears were obtained. Contralateral ear measurements were used for hearing normalization to account for presbycusis. RESULTS: Fifty-six patients with median audiologic follow-up 2.0 yr (mean 2.66 yr, min-max 0.50-9.45 yr) were included. Patients treated with single fractionation had a significantly worsened SAT (dB) compared to patients treated with 5 fractions (P = .008) and compared to all multifraction patients (P = .009) at 12 to 24 mo follow-up. CONCLUSION: This retrospective analysis supports the use of fractionated SRS to preserve hearing in patients with VS. SAT can be used as an objective metric of hearing response to radiosurgery.

Striatal Mitochondrial Disruption following Severe Traumatic Brain Injury.

Traumatic brain injury (TBI) results in oxidative stress and calcium dysregulation in mitochondria. However, little work has examined perturbations of mitochondrial homeostasis in peri-injury tissue. We examined mitochondrial homeostasis after a unilateral controlled cortical impact over the sensorimotor cortex in adult male rats. There was a significant reduction in peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) messenger RNA (mRNA) at post-injury days 3 and 6 and a transient reduction in mitochondrial DNA copy number at 3 days post-injury that recovered by 6 days in the ipsi-injury striatum. In ipsilateral cortex, PGC-1α mRNA was reduced only at 6 days post-injury. Additionally, expression of mitochondrial-encoded mRNAs, cytochrome c oxidase subunit 1 and NADH dehydrogenase subunit 1, was decreased at 3 and 6 days post-injury in ipsilesional striatum and at 6 days post-injury in ipsilesional cortex. There was no observable decrease in nuclear-encoded mRNAs mitochondrial transcription factor A or NADH dehydrogenase (ubiquinone) Fe-S protein 1. We detected an acute increase in superoxide dismutase 2 mRNA expression, as well as an induction of microRNA (miR)-21 and miR-155, which have been previously demonstrated to disrupt mitochondrial homeostasis. Behaviorally, rats with TBI exhibited marked error rates in contrainjury forelimb performance on the ladder test. These findings reveal that there may be differential susceptibilities of various peri-injury brain structures to mitochondrial dysfunction and associated behavioral deficits, and that molecular pathways demonstrated to interfere with mitochondrial homeostasis and function are activated subacutely post-TBI.

Rapid Renal Regulation of Peroxisome Proliferator-activated Receptor γ Coactivator-1α by Extracellular Signal-Regulated Kinase 1/2 in Physiological and Pathological Conditions.

Previous studies have shown that extracellular signal-regulated kinase 1/2 (ERK1/2) directly inhibits mitochondrial function during cellular injury. We evaluated the role of ERK1/2 on the expression of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) gene, a master regulator of mitochondrial function. The potent and specific MEK1/2 inhibitor trametinib rapidly blocked ERK1/2 phosphorylation, decreased cytosolic and nuclear FOXO3a/1 phosphorylation, and increased PGC-1α gene expression and its downstream mitochondrial biogenesis (MB) targets under physiological conditions in the kidney cortex and in primary renal cell cultures. The epidermal growth factor receptor (EGFR) inhibitor erlotinib blocked ERK1/2 phosphorylation and increased PGC-1α gene expression similar to treatment with trametinib, linking EGFR activation and FOXO3a/1 inactivation to the down-regulation of PGC-1α and MB through ERK1/2. Pretreatment with trametinib blocked early ERK1/2 phosphorylation following ischemia/reperfusion kidney injury and attenuated the down-regulation of PGC-1α and downstream target genes. These results demonstrate that ERK1/2 rapidly regulates mitochondrial function through a novel pathway, EGFR/ERK1/2/FOXO3a/1/PGC-1α, under physiological and pathological conditions. As such, ERK1/2 down-regulates mitochondrial function directly by phosphorylation of upstream regulators of PGC-1α and subsequently decreasing MB.

Mitochondrial Biogenesis as a Pharmacological Target: A New Approach to Acute and Chronic Diseases.

Mitochondrial dysfunction is a key pathophysiological component of many acute and chronic diseases. Maintenance of mitochondrial homeostasis through the balance of mitochondrial turnover, fission and fusion, and generation of new mitochondria via mitochondrial biogenesis is critical for tissue health. Pharmacological activation of mitochondrial biogenesis can enhance oxidative metabolism and tissue bioenergetics, and improve organ function in conditions characterized by mitochondrial dysfunction. However, owing to the complexity of mitochondrial assembly and maintenance, identification of specific activators of mitochondrial biogenesis has been difficult. This review provides an overview of the role of mitochondrial dysfunction in acute and chronic diseases, details the current state of therapeutics for the stimulation of mitochondrial biogenesis and their effects on disease outcomes, describes new screening methodologies to identify novel stimulators and noncanonical pathways of mitochondrial biogenesis, and discusses potential hurdles of mitochondrial biogenesis as a therapeutic strategy.

Urinary mitochondrial DNA is a biomarker of mitochondrial disruption and renal dysfunction in acute kidney injury.

Recent studies show the importance of mitochondrial dysfunction in the initiation and progression of acute kidney injury (AKI). However, no biomarkers exist linking renal injury to mitochondrial function and integrity. To this end, we evaluated urinary mitochondrial DNA (UmtDNA) as a biomarker of renal injury and function in humans with AKI following cardiac surgery. mtDNA was isolated from the urine of patients following cardiac surgery and quantified by quantitative PCR. Patients were stratified into no AKI, stable AKI, and progressive AKI groups based on Acute Kidney Injury Network (AKIN) staging. UmtDNA was elevated in progressive AKI patients and was associated with progression of patients with AKI at collection to higher AKIN stages. To evaluate the relationship of UmtDNA to measures of renal mitochondrial integrity in AKI, mice were subjected to sham surgery or varying degrees of ischemia followed by 24 h of reperfusion. UmtDNA increased in mice after 10-15 min of ischemia and positively correlated with ischemia time. Furthermore, UmtDNA was predictive of AKI in the mouse model. Finally, UmtDNA levels were negatively correlated with renal cortical mtDNA and mitochondrial gene expression. These translational studies demonstrate that UmtDNA is associated with recovery from AKI following cardiac surgery by serving as an indicator of mitochondrial integrity. Thus UmtDNA may serve as valuable biomarker for the development of mitochondrial-targeted therapies in AKI.

Urinary ATP Synthase Subunit ß Is a Novel Biomarker of Renal Mitochondrial Dysfunction in Acute Kidney Injury.

Although the importance of mitochondrial dysfunction in acute kidney injury (AKI) has been documented, noninvasive early biomarkers of mitochondrial damage are needed. We examined urinary ATP synthase subunit ß (ATPSß) as a biomarker of renal mitochondrial dysfunction during AKI. Mice underwent sham surgery or varying degrees (5, 10, or 15 min ischemia) of ischemia/reperfusion (I/R)-induced AKI. Serum creatinine, BUN, and neutrophil gelatinase-associated lipocalin were elevated only in the 15 min I/R group at 24 h. Immunoblot analysis of urinary ATPSß revealed two bands (full length ∼52 kDa and cleaved ∼25 kDa), both confirmed as ATPSß by LC-MS/MS, that increased at 24 h in 10- and 15-min I/R groups. These changes were associated with mitochondrial dysfunction evidenced by reduced renal cortical expression of mitochondrial proteins, ATPSß and COX1, proximal tubular oxygen consumption, and ATP. Furthermore, in the 15-min I/R group, urinary ATPSß was elevated until 72 h before returning to baseline 144 h after reperfusion with recovery of renal function. Evaluation of urinary ATPSß in a nonalcoholic steatohepatitis model of liver injury only revealed cleaved ATPSß, suggesting specificity of full-length ATPSß for renal injury. Immunoblot analyses of patient urine samples collected 36 h after cardiac surgery revealed increased urinary ATPSß levels in patients with postcardiac surgery-induced AKI. LC-MS/MS urinalysis in human subjects with AKI confirmed increased ATPSß. These translational studies provide evidence that ATPSß may be a novel and sensitive urinary biomarker of renal mitochondrial dysfunction and could serve as valuable tool for the testing of potential therapies for AKI and chemical-induced nephrotoxicity.

Agonism of the 5-hydroxytryptamine 1F receptor promotes mitochondrial biogenesis and recovery from acute kidney injury.

Many acute and chronic conditions, such as acute kidney injury, chronic kidney disease, heart failure, and liver disease, involve mitochondrial dysfunction. Although we have provided evidence that drug-induced stimulation of mitochondrial biogenesis (MB) accelerates mitochondrial and cellular repair, leading to recovery of organ function, only a limited number of chemicals have been identified that induce MB. The goal of this study was to assess the role of the 5-hydroxytryptamine 1F (5-HT1F) receptor in MB. Immunoblot and quantitative polymerase chain reaction analyses revealed 5-HT1F receptor expression in renal proximal tubule cells (RPTC). A MB screening assay demonstrated that two selective 5-HT1F receptor agonists, LY334370 (4-fluoro-N-[3-(1-methyl-4-piperidinyl)-1H-indol-5-yl]benzamide) and LY344864 (N-[(3R)-3-(dimethylamino)-2,3,4,9-tetrahydro-1H-carbazol-6-yl]-4-fluorobenzamide; 1-100 nM) increased carbonylcyanide-p-trifluoromethoxyphenylhydrazone-uncoupled oxygen consumption in RPTC, and validation studies confirmed both agonists increased mitochondrial proteins [e.g., ATP synthase ß, cytochrome c oxidase 1 (Cox1), and NADH dehydrogenase (ubiquinone) 1ß subcomplex subunit 8 (NDUFB8)] in vitro. Small interfering RNA knockdown of the 5-HT1F receptor blocked agonist-induced MB. Furthermore, LY344864 increased peroxisome proliferator-activated receptor coactivator 1-α, Cox1, and NDUFB8 transcript levels and mitochondrial DNA (mtDNA) copy number in murine renal cortex, heart, and liver. Finally, LY344864 accelerated recovery of renal function, as indicated by decreased blood urea nitrogen and kidney injury molecule 1 and increased mtDNA copy number following ischemia/reperfusion-induced acute kidney injury (AKI). In summary, these studies reveal that the 5-HT1F receptor is linked to MB, 5-HT1F receptor agonism promotes MB in vitro and in vivo, and 5-HT1F receptor agonism promotes recovery from AKI injury. Induction of MB through 5-HT1F receptor agonism represents a new target and approach to treat mitochondrial organ dysfunction.

Suppressed mitochondrial biogenesis in folic acid-induced acute kidney injury and early fibrosis.

Acute kidney injury (AKI) is a disease with mitochondrial dysfunction and a newly established risk factor for the development of chronic kidney disease (CKD) and fibrosis. We examined mitochondrial homeostasis in the folic acid (FA)-induced AKI model that develops early fibrosis over a rapid time course. Mice given a single dose of FA had elevated serum creatinine (3-fold) and urine glucose (2.2-fold) 1 and 2 d after injection that resolved by 4d. In contrast, peroxisome proliferator gamma coactivator 1α (PGC-1α) and mitochondrial transcription factor A (TFAM), critical transcriptional regulators of mitochondrial biogenesis (MB), were down-regulated ∼80% 1d after FA injection and remained depressed through 14 d. Multiple electron transport chain and ATP synthesis genes were also down-regulated from 1 to 14 d after FA, including NADH dehydrogenase (ubiquinone) 1 beta subcomplex 8 (NDUFß8), ATP synthase subunit ß (ATPS-ß), and cytochrome C oxidase subunit I (COXI). Mitochondrial DNA copy number was reduced ∼50% from 2 to 14 d after FA injection. Protein levels of early fibrosis markers α-smooth muscle actin and transforming growth factor ß1 were elevated at 6 and 14 d after FA. Picrosirius red staining and collagen 1A2 (COL1A2) IHC revealed staining for mature collagen deposition at 14 d. We propose that mitochondrial dysfunction induced by AKI is a persistent cellular injury that promotes progression to fibrosis and CKD, and that this model can be used to test mitochondrial therapeutics that limit progression to fibrosis and CKD.

cGMP-selective phosphodiesterase inhibitors stimulate mitochondrial biogenesis and promote recovery from acute kidney injury.

Recent studies demonstrate that mitochondrial dysfunction is a mediator of acute kidney injury (AKI). Consequently, restoration of mitochondrial function after AKI may be key to the recovery of renal function. Mitochondrial function can be restored through the generation of new, functional mitochondria in a process called mitochondrial biogenesis (MB). Despite its potential therapeutic significance, very few pharmacological agents have been identified to induce MB. To examine the efficacy of phosphodiesterase (PDE) inhibitors (PDE3: cAMP and cGMP activity; and PDE4: cAMP activity) in stimulating MB, primary cultures of renal proximal tubular cells (RPTCs) were treated with a panel of inhibitors for 24 hours. PDE3, but not PDE4, inhibitors increased the FCCP-uncoupled oxygen consumption rate (OCR), a marker of MB. Exposure of RPTCs to the PDE3 inhibitors, cilostamide and trequinsin, for 24 hours increased peroxisome proliferator-activated receptor γ coactivator-1α, and multiple mitochondrial electron transport chain genes. Cilostamide and trequinsin also increased mRNA expression of mitochondrial genes and mitochondrial DNA copy number in mice renal cortex. Consistent with these experiments, 8-Br-cGMP increased FCCP-uncoupled OCR and mitochondrial gene expression, whereas 8-Br-cAMP had no effect. The cGMP-specific PDE5 inhibitor sildenafil also induced MB in RPTCs and in vivo in mouse renal cortex. Treatment of mice with sildenafil after folic acid-induced AKI promoted restoration of MB and renal recovery. These data provide strong evidence that specific PDE inhibitors that increase cGMP are inducers of MB in vitro and in vivo, and suggest their potential efficacy in AKI and other diseases characterized by mitochondrial dysfunction and suppressed MB.

Calpain 10 homology modeling with CYGAK and increased lipophilicity leads to greater potency and efficacy in cells.

Calpain 10 is a ubiquitously expressed mitochondrial and cytosolic Ca(2+)-regulated cysteine protease in which overexpression or knockdown leads to mitochondrial dysfunction and cell death. We previously identified a potent and specific calpain 10 peptide inhibitor (CYGAK), but it was not efficacious in cells. Therefore, we created a homology model using the calpain 10 amino acid sequence and calpain 1 3-D structure and docked CYGAK in the active site. Using this model we modified the inhibitor to improve potency 2-fold (CYGAbuK). To increase cellular efficacy, we created CYGAK-S-phenyl-oleic acid heterodimers. Using renal mitochondrial matrix CYGAK, CYGAK-OC, and CYGAK-ON had IC(50)'s of 70, 90, and 875 nM, respectively. Using isolated whole renal mitochondria CYGAK, CYGAK-OC, and CYGAK-ON had IC(50)'s of 95, 196, and >10,000 nM, respectively. Using renal proximal tubular cells (RPTC) in primary culture, 30 min exposures to CYGAK-OC and CYGAbuK-OC decreased cellular calpain activity approximately 20% at 1 µM, and concentrations up to 100 µM had no additional effect. RPTC treated with 10 µM CYGAK-OC for 24 h induced accumulation of ATP synthase ß and NDUFB8, two calpain 10 substrates. In summary, we used molecular modeling to improve the potency of CYGAK, while creating CYGAK-oleic acid heterodimers to improve efficacy in cells. Since calpain 10 has been implicated in type 2 diabetes and renal aging, the use of this inhibitor may contribute to elucidating the role of calpain 10 in these and other diseases.

Systemic administration of optimized aptamer-siRNA chimeras promotes regression of PSMA-expressing tumors.

Prostate cancer cells expressing prostate-specific membrane antigen (PSMA) have been targeted with RNA aptamer-small interfering (si)RNA chimeras, but therapeutic efficacy in vivo was demonstrated only with intratumoral injection. Clinical translation of this approach will require chimeras that are effective when administered systemically and are amenable to chemical synthesis. To these ends, we enhanced the silencing activity and specificity of aptamer-siRNA chimeras by incorporating modifications that enable more efficient processing of the siRNA by the cellular machinery. These included adding 2-nucleotide 3'-overhangs and optimizing the thermodynamic profile and structure of the duplex to favor processing of the siRNA guide strand. We also truncated the aptamer portion of the chimeras to facilitate large-scale chemical synthesis. The optimized chimeras resulted in pronounced regression of PSMA-expressing tumors in athymic mice after systemic administration. Anti-tumor activity was further enhanced by appending a polyethylene glycol moiety, which increased the chimeras' circulating half-life.