Development of an orally bioavailable mSWI/SNF ATPase degrader and acquired mechanisms of resistance in prostate cancer.

Mammalian switch/sucrose nonfermentable (mSWI/SNF) ATPase degraders have been shown to be effective in enhancer-driven cancers by functioning to impede oncogenic transcription factor chromatin accessibility. Here, we developed AU-24118, an orally bioavailable proteolysis-targeting chimera (PROTAC) degrader of mSWI/SNF ATPases (SMARCA2 and SMARCA4) and PBRM1. AU-24118 demonstrated tumor regression in a model of castration-resistant prostate cancer (CRPC) which was further enhanced with combination enzalutamide treatment, a standard of care androgen receptor (AR) antagonist used in CRPC patients. Importantly, AU-24118 exhibited favorable pharmacokinetic profiles in preclinical analyses in mice and rats, and further toxicity testing in mice showed a favorable safety profile. As acquired resistance is common with targeted cancer therapeutics, experiments were designed to explore potential mechanisms of resistance that may arise with long-term mSWI/SNF ATPase PROTAC treatment. Prostate cancer cell lines exposed to long-term treatment with high doses of a mSWI/SNF ATPase degrader developed SMARCA4 bromodomain mutations and ABCB1 (ATP binding cassette subfamily B member 1) overexpression as acquired mechanisms of resistance. Intriguingly, while SMARCA4 mutations provided specific resistance to mSWI/SNF degraders, ABCB1 overexpression provided broader resistance to other potent PROTAC degraders targeting bromodomain-containing protein 4 and AR. The ABCB1 inhibitor, zosuquidar, reversed resistance to all three PROTAC degraders tested. Combined, these findings position mSWI/SNF degraders for clinical translation for patients with enhancer-driven cancers and define strategies to overcome resistance mechanisms that may arise.

Targeting PIKfyve-driven lipid homeostasis as a metabolic vulnerability in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) subsists in a nutrient-deregulated microenvironment, making it particularly susceptible to treatments that interfere with cancer metabolism12. For example, PDAC utilizes and is dependent on high levels of autophagy and other lysosomal processes3-5. Although targeting these pathways has shown potential in preclinical studies, progress has been hampered by the challenge of identifying and characterizing favorable targets for drug development6. Here, we characterize PIKfyve, a lipid kinase integral to lysosomal functioning7, as a novel and targetable vulnerability in PDAC. In human patient and murine PDAC samples, we discovered that PIKFYVE is overexpressed in PDAC cells compared to adjacent normal cells. Employing a genetically engineered mouse model, we established the essential role of PIKfyve in PDAC progression. Further, through comprehensive metabolic analyses, we found that PIKfyve inhibition obligated PDAC to upregulate de novo lipid synthesis, a relationship previously undescribed. PIKfyve inhibition triggered a distinct lipogenic gene expression and metabolic program, creating a dependency on de novo lipid metabolism pathways, by upregulating genes such as FASN and ACACA. In PDAC, the KRAS-MAPK signaling pathway is a primary driver of de novo lipid synthesis, specifically enhancing FASN and ACACA levels. Accordingly, the simultaneous targeting of PIKfyve and KRAS-MAPK resulted in the elimination of tumor burden in a syngeneic orthotopic model and tumor regression in a xenograft model of PDAC. Taken together, these studies suggest that disrupting lipid metabolism through PIKfyve inhibition induces synthetic lethality in conjunction with KRAS-MAPK-directed therapies for PDAC.

CDK12 Loss Promotes Prostate Cancer Development While Exposing Vulnerabilities to Paralog-Based Synthetic Lethality.

Biallelic loss of cyclin-dependent kinase 12 (CDK12) defines a unique molecular subtype of metastatic castration-resistant prostate cancer (mCRPC). It remains unclear, however, whether CDK12 loss per se is sufficient to drive prostate cancer development-either alone, or in the context of other genetic alterations-and whether CDK12-mutant tumors exhibit sensitivity to specific pharmacotherapies. Here, we demonstrate that tissue-specific Cdk12 ablation is sufficient to induce preneoplastic lesions and robust T cell infiltration in the mouse prostate. Allograft-based CRISPR screening demonstrated that Cdk12 loss is positively associated with Trp53 inactivation but negatively associated with Pten inactivation-akin to what is observed in human mCRPC. Consistent with this, ablation of Cdk12 in prostate organoids with concurrent Trp53 loss promotes their proliferation and ability to form tumors in mice, while Cdk12 knockout in the Pten-null prostate cancer mouse model abrogates tumor growth. Bigenic Cdk12 and Trp53 loss allografts represent a new syngeneic model for the study of androgen receptor (AR)-positive, luminal prostate cancer. Notably, Cdk12/Trp53 loss prostate tumors are sensitive to immune checkpoint blockade. Cdk12-null organoids (either with or without Trp53 co-ablation) and patient-derived xenografts from tumors with CDK12 inactivation are highly sensitive to inhibition or degradation of its paralog kinase, CDK13. Together, these data identify CDK12 as a bona fide tumor suppressor gene with impact on tumor progression and lends support to paralog-based synthetic lethality as a promising strategy for treating CDK12-mutant mCRPC.

Development of an orally bioavailable mSWI/SNF ATPase degrader and acquired mechanisms of resistance in prostate cancer.

Mammalian switch/sucrose non-fermentable (mSWI/SNF) ATPase degraders have been shown to be effective in enhancer-driven cancers by functioning to impede oncogenic transcription factor chromatin accessibility. Here, we developed AU-24118, a first-in-class, orally bioavailable proteolysis targeting chimera (PROTAC) degrader of mSWI/SNF ATPases (SMARCA2 and SMARCA4) and PBRM1. AU-24118 demonstrated tumor regression in a model of castration-resistant prostate cancer (CRPC) which was further enhanced with combination enzalutamide treatment, a standard of care androgen receptor (AR) antagonist used in CRPC patients. Importantly, AU-24118 exhibited favorable pharmacokinetic profiles in preclinical analyses in mice and rats, and further toxicity testing in mice showed a favorable safety profile. As acquired resistance is common with targeted cancer therapeutics, experiments were designed to explore potential mechanisms of resistance that may arise with long-term mSWI/SNF ATPase PROTAC treatment. Prostate cancer cell lines exposed to long-term treatment with high doses of a mSWI/SNF ATPase degrader developed SMARCA4 bromodomain mutations and ABCB1 overexpression as acquired mechanisms of resistance. Intriguingly, while SMARCA4 mutations provided specific resistance to mSWI/SNF degraders, ABCB1 overexpression provided broader resistance to other potent PROTAC degraders targeting bromodomain-containing protein 4 (BRD4) and AR. The ABCB1 inhibitor, zosuquidar, reversed resistance to all three PROTAC degraders tested. Combined, these findings position mSWI/SNF degraders for clinical translation for patients with enhancer-driven cancers and define strategies to overcome resistance mechanisms that may arise.

Targeting the lipid kinase PIKfyve upregulates surface expression of MHC class I to augment cancer immunotherapy.

Despite the remarkable clinical success of immunotherapies in a subset of cancer patients, many fail to respond to treatment and exhibit resistance. Here, we found that genetic or pharmacologic inhibition of the lipid kinase PIKfyve, a regulator of autophagic flux and lysosomal biogenesis, upregulated surface expression of major histocompatibility complex class I (MHC-I) in cancer cells via impairing autophagic flux, resulting in enhanced cancer cell killing mediated by CD8+ T cells. Genetic depletion or pharmacologic inhibition of PIKfyve elevated tumor-specific MHC-I surface expression, increased intratumoral functional CD8+ T cells, and slowed tumor progression in multiple syngeneic mouse models. Importantly, enhanced antitumor responses by Pikfyve-depletion were CD8+ T cell- and MHC-I-dependent, as CD8+ T cell depletion or B2m knockout rescued tumor growth. Furthermore, PIKfyve inhibition improved response to immune checkpoint blockade (ICB), adoptive cell therapy, and a therapeutic vaccine. High expression of PIKFYVE was also predictive of poor response to ICB and prognostic of poor survival in ICB-treated cohorts. Collectively, our findings show that targeting PIKfyve enhances immunotherapies by elevating surface expression of MHC-I in cancer cells, and PIKfyve inhibitors have potential as agents to increase immunotherapy response in cancer patients.

Discovery of a First-in-Class Degrader for the Lipid Kinase PIKfyve.

The phosphoinositide kinase PIKfyve has emerged as a new potential therapeutic target in various cancers. However, limited clinical progress has been achieved with PIKfyve inhibitors. Here, we report the discovery of a first-in-class PIKfyve degrader 12d (PIK5-12d) by employing the proteolysis-targeting chimera approach. PIK5-12d potently degraded PIKfyve protein with a DC50 value of 1.48 nM and a Dmax value of 97.7% in prostate cancer VCaP cells. Mechanistic studies revealed that it selectively induced PIKfyve degradation in a VHL- and proteasome-dependent manner. PIKfyve degradation by PIK5-12d caused massive cytoplasmic vacuolization and blocked autophagic flux in multiple prostate cancer cell lines. Importantly, PIK5-12d was more effective in suppressing the growth of prostate cancer cells than the parent inhibitor and exerted prolonged inhibition of downstream signaling. Further, intraperitoneal administration of PIK5-12d exhibited potent PIKfyve degradation and suppressed tumor proliferation in vivo. Overall, PIK5-12d is a valuable chemical tool for exploring PIKfyve-based targeted therapy.

Proxalutamide reduces SARS-CoV-2 infection and associated inflammatory response.

Early in the COVID-19 pandemic, data suggested that males had a higher risk of developing severe disease and that androgen deprivation therapy might be associated with protection. Combined with the fact that TMPRSS2 (transmembrane serine protease 2), a host entry factor for the SARS-CoV-2 virus, was a well-known androgen-regulated gene, this led to an upsurge of research investigating androgen receptor (AR)-targeting drugs. Proxalutamide, an AR antagonist, was shown in initial clinical studies to benefit COVID-19 patients; however, further validation is needed as one study was retracted. Due to continued interest in proxalutamide, which is in phase 3 trials, we examined its ability to impact SARS-CoV-2 infection and downstream inflammatory responses. Proxalutamide exerted similar effects as enzalutamide, an AR antagonist prescribed for advanced prostate cancer, in decreasing AR signaling and expression of TMPRSS2 and angiotensin-converting enzyme 2 (ACE2), the SARS-CoV-2 receptor. However, proxalutamide led to degradation of AR protein, which was not observed with enzalutamide. Proxalutamide inhibited SARS-CoV-2 infection with an IC50 value of 97 nM, compared to 281 nM for enzalutamide. Importantly, proxalutamide inhibited infection by multiple SARS-CoV-2 variants and synergized with remdesivir. Proxalutamide protected against cell death in response to tumor necrosis factor alpha and interferon gamma, and overall survival of mice was increased with proxalutamide treatment prior to cytokine exposure. Mechanistically, we found that proxalutamide increased levels of NRF2, an essential transcription factor that mediates antioxidant responses, and decreased lung inflammation. These data provide compelling evidence that proxalutamide can prevent SARS-CoV-2 infection and cytokine-induced lung damage, suggesting that promising clinical data may emerge from ongoing phase 3 trials.

A 61-year-old woman with jejunal lymphatic malformation visualized on computed tomography: a case report.

BACKGROUND: Jejunal lymphatic malformations are congenital lesions that are seldom diagnosed in adults and rarely seen on imaging. CASE PRESENTATION: A 61-year-old Caucasian woman was initially diagnosed and treated for mucinous ovarian carcinoma. After an exploratory laparotomy with left salpingo-oophorectomy, a computed tomography scan of the abdomen and pelvis demonstrated suspicious fluid-containing lesions involving a segment of jejunum and adjacent mesentery. Resection of the lesion during subsequent debulking surgery revealed that the lesion seen on imaging was a jejunal lymphatic malformation and not a cancerous implant. CONCLUSIONS: Abdominal lymphatic malformations are difficult to diagnose solely on imaging but should remain on the differential in adult cancer patients with persistent cystic abdominal lesions despite chemotherapy and must be differentiated from metastatic implants.

Platelet Mapping by Thromboelastography and Whole Blood Aggregometry in Adult Patients Supported by Mechanical Circulatory Support Device on Aspirin Therapy.

Patients on mechanical circulatory support (MCS) devices are placed on aspirin and may require platelet function testing (PFT) to monitor the adequacy of therapy. Routine laboratory PFT is performed using whole blood aggregation (WBA) which typically has a long turnaround time (4-5 hours) and may not be readily available. By contrast, platelet mapping by thromboelastography (TPM) can provide results within 45 minutes. The objective of this study was to compare the results of TPM with WBA. We compared platelet mapping maximal amplitude (MA) by TPM with that of arachidonic acid (AA) to WBA with AA by impedance. We analyzed paired samples where both TPM and WBA were available. Of 45 paired samples, 34 were from 29 MCS patients and 11 were from non-MCS patients. When applying institutional interpretation guidelines with an MAActivator cutoff of ≤40 mm, WBAAA vs TPM MAAA in non-MCS and MCS patients correlated well with an accuracy of 100 and 94.4%, respectively. MAActivator >40 had poor correlation with an accuracy of 37.5%. Irrespective of MAActivator value, TPM AA inhibition expressed in percent of inhibition had poor accuracy. When used with proper guidelines for interpretation, specifically when MAActivator ≤ 40 mm, TPM is a suitable and reliable test to use for MCS patients on aspirin.

Transfusion Medicine Equations Made Internet Accessible.

Multiple mathematical equations inform the practice of transfusion medicine. These equations apply to a wide range of topics: dosage of blood products, calculation of fluid volumes, and even specific treatment decisions (e.g. corrected count increment for determination of platelet refractoriness). The calculation of these equations can be complicated, prone to error, and time-consuming. A trusted source is needed to accurately perform these calculations 24 hours a day without error and without monetary cost. We sought to build internet-enabled calculators relevant to the practice of transfusion medicine. We partnered with MDCalc, an online host of medical calculators with 1 million monthly users in 196 countries, to design and host the calculators. The calculators guide users in the application of transfusion medicine equations by providing indications for use, inputs for the equations variables, error-checking, warnings for bad inputs, and interpretive guidance of the result. The following calculators were built: blood volume, corrected count increment (CCI), plasma dosage, cryoprecipitated antihemophilic factor dosage, approximate number of units for compatibility testing, maternal-fetal hemorrhage Rh(D) immune globulin dosage, intrauterine RBC transfusion dosage, neonatal polycythemia partial exchange, theoretical removal of a substance by plasmapheresis, sickle cell RBC exchange volume, peripheral blood stem cell collection, and a calculator relevant to donor lymphocyte infusion. Clinicians can now utilize this reputable and highly visible online source to access these common transfusion medicine equations at any time with an internet-enabled device (https://www.mdcalc.com/search?filter=transfusion+medicine).

Reducing Rejected Fecal Immunochemical Tests Received in the Laboratory for Colorectal Cancer Screening.

BACKGROUND: Colorectal cancer (CRC) screening decreases CRC incidence; however, many patients are not successfully screened. PURPOSE: To improve screening rates at our institution by decreasing the rate of rejected fecal immunochemical tests (FITs), a means of CRC screening, from 28.6% to <10% by December 2017. METHODS: Specimens were rejected for the following reasons: expired specimen, lack of recorded collection date/time, lack of physician orders, incomplete patient information, and illegible handwriting. Multidisciplinary teams devised the following interventions: FIT envelope reminder stickers, automated FIT patient reminder phone calls, a laboratory standard operating procedure, an accessioning process at satellite laboratories, revisions to a clinical reminder when offering FIT, and provision of FIT-compatible printers to clinics. RESULTS: Total specimens received each month ranged from 647 to 970. Fecal immunochemical test rejection rates fell from 28.6% in June 2017 to 6.9% in December 2017 with a statistically significant decrease (p-value = .015) between the intervention period (May 2017-October 2017) and the postintervention period (November 2017-May 2018). CONCLUSIONS: Targeted interventions with stakeholder involvement are essential in reducing the rejection rate. IMPLICATIONS: The decreased rejection rate saves resources by decreasing the need to rescreen patients whose specimens were rejected, and may improve CRC screening rates.

Using Multisite Process Mapping to Aid Care Improvement: An Examination of Inpatient Suicide-Screening Procedures.

Although most suicides occur outside of medical settings, a critical and often overlooked subgroup of patients attempt and complete suicide within general medical and inpatient units. The purpose of this quality improvement initiative was to perform a baseline assessment of the current practices for suicide prevention within medical inpatient units across eight Veterans Affairs medical centers throughout the nation, as part of the VA Quality Scholars (VAQS) fellowship training program. In conjunction with the VAQS national curriculum, the authors and their colleagues used multisite process mapping and developed a heuristic process to identify best practices and improvement recommendations with the hopes of advancing knowledge related to a key organizational priority-suicide prevention. Findings demonstrate a multitude of benefits arising from this process, both in relation to system-level policy change as well as site-based clinical care. This interprofessional and multisite approach provided an avenue for process literacy and consensus building, resulting in the identification of strengths including the improvement of prevention efforts and accessibility of supportive resources, the discovery of opportunities for improvement related to risk detection and response and the patient centeredness of current prevention efforts, and the provision of solutions that aim to achieve sustained change across a complex health system.

Therapeutic Plasma Exchange and Its Impact on Drug Levels: An ACLPS Critical Review.

OBJECTIVES: To examine and summarize the current literature on the effects of therapeutic plasma exchange on medication levels. METHODS: Literature review was performed via searches of the Cochrane Database and PubMed-MEDLINE (1996 to August 2016) looking for all case reports, case series, and human randomized controlled trials involving therapeutic plasma exchange (TPE)-associated drug removal. RESULTS: Approximately 60 peer-reviewed articles were identified with the majority being case reports; no randomized controlled trials were identified. These reports and the authors' own experiences were used to derive practical guidance regarding the effect of TPE on circulating drug levels. CONCLUSIONS: There were several limitations with existing studies, many of which relate to procedural and/or clinical properties of patients undergoing TPE. As such, additional studies are needed before definitive guidelines can be established. There is clear need for development of consensus and additional investigations in this domain.

Alitretinoin: a comprehensive review.

BACKGROUND: Alitretinoin (9-cis-retinoic acid) is a unique panagonist retinoid, capable of binding to all six known retinoid receptors (RAR-alpha, -beta, -gamma, and RXR-alpha, -beta, -gamma). Studies are being carried out to determine how best to utilize this characteristic in treatments for conditions such as chronic hand dermatitis. OBJECTIVE: To review the literature on alitretinoin. METHODS: The scope of the review encompasses ways that alitretinoin is currently and may potentially be utilized. RESULTS/CONCLUSIONS: Orally administered alitretinoin is a safe and effective treatment for chronic hand dermatitis. Topical treatment with alitretinoin can be expanded into other areas such as photoaged skin and cutaneous T-cell lymphoma. Despite these benefits, oral alitretinoin will face a difficult path attaining approval for use in the US.

dextro-Naloxone or levo-naloxone reverses the attenuation of morphine antinociception induced by lipopolysaccharide in the mouse spinal cord via a non-opioid mechanism.

Glial stimulation by intrathecal injection of lipopolysaccharide (LPS) attenuated the tail-flick inhibition produced by morphine given intrathecally in the spinal cord of the male CD-1 mice. The phenomenon has been defined as antianalgesia. The effects of dextro-naloxone or levo-naloxone on the attenuation of morphine-produced tail-flick inhibition induced by LPS were then studied. Pretreatment with dextro-naloxone or levo-naloxone reversed the attenuation of the morphine-produced tail-flick inhibition induced by LPS. Pretreatment with dextro-naloxone or levo-naloxone alone did not affect the morphine-produced tail-flick inhibition. It is concluded that dextro-naloxone and levo-naloxone block the LPS-induced antianalgesia against morphine antinociception via a non-opioid mechanism.

p38 mitogen-activated protein kinase inhibitor SB203580 reverses the antianalgesia induced by dextro-morphine or morphine in the mouse spinal cord.

We have previously demonstrated that intrathecal pretreatment with dextro-morphine or morphine attenuates the morphine-produced antinociception. The phenomenon has been defined as antianalgesia, which is mediated by a non-opioid receptor [Wu, H., Thompson, J., Sun, H., Terashvili, M., Tseng, L.F., 2005. Antianalgesia: stereo-selective action of dextro-morphine over levo-morphine on glia in the mouse spinal cord. J. Pharmacol. Exp. Ther. 314, 1101-1108]. To determine if p38 mitogen-activated protein kinase (MAPK) is involved in the antianalgesia, the effects of p38 MAPK inhibitor 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)-1H-imidazole (SB203580) on the attenuation of the morphine-produced tail-flick inhibition induced by dextro-morphine or morphine were studied in male CD-1 mice. Intrathecal pretreatment with SB203580 (24.2 nmol) reversed the attenuation of the morphine-produced tail-flick inhibition induced by dextro-morphine (33 fmol) or morphine (0.3 nmol) pretreatment. The finding indicates that the antianalgesia induced by dextro-morphine or morphine is mediated by the activation of p38 MAPK in the mouse spinal cord.