Citations

Abstract Pancreatic ductal adenocarcinoma (PDAC) is characterized by KRAS- and autophagy-dependent tumorigenic growth. We determined the role of mutationally activated KRAS, found in ~95% of PDAC, in supporting autophagy. Surprisingly, acute KRAS suppression, which blocks proliferation, was associated with increased rather than decreased autophagic flux. Pharmacologic inhibition of ERK MAPK phenocopied the genetic silencing of KRAS and also increased autophagic flux. We speculated that the loss of ERK-driven metabolic processes may induce compensatory mechanisms to increase autophagy. Addressing a mechanism for ERK suppression-increased autophagy, we describe three mechanisms: 1) ERK inhibition-mediated increased transcription of autophagy and lysosomal genes, 2) ERK inhibitor-induced AMPK activation and suppression of mTOR signaling, and 3) ERK inhibition-facilitated decreased glycolytic flux. We then addressed whether ERK inhibition increased PDAC dependence on autophagy. Supporting this possibility, we found that cotreatment with the autophagy inhibitor chloroquine (CQ) synergistically enhanced ERK inhibitor-mediated antiproliferative activity. Similarly, genetic or pharmacologic inhibition of specific regulators of autophagy also enhanced ERK inhibitor activity. Encouraged by the synergistic relationship between ERK and autophagy inhibition, we performed a CRISPR/Cas-9 mediated genetic loss of function screen in the presence of CQ to determine additional sensitizers as well as mediators of resistance to autophagy inhibition. Top sensitizers included multiple mediators of the DNA damage response. One such sensitizing gene was CHEK1, which encodes the CHK1 serine/threonine kinase, required for checkpoint-mediated cell cycle arrest and activation of DNA repair in response to DNA damage. Accordingly, we showed that treatment with prexasertib, a clinical candidate CHK1 inhibitor, increased autophagic flux in PDAC cells and synergized with CQ to decrease PDAC cell proliferation and increase apoptosis. We conclude that concurrent suppression of multiple metabolic processes, to block compensatory rebound activities, will be needed for effective PDAC treatment. This abstract is also being presented as Poster B07. Citation Format: Kirsten L. Bryant, Jennifer E. Klomp, Ye S. Lee, Clint A. Stalnecker, Kajal R. Grover, A. Cole Edwards, Sen Peng, Mariaelena Pierobon, Emanuel F. Petricoin III, Nhan Tran, Alec C. Kimmelman, Adrienne D. Cox, Channing J. Der. Enhancing the effect of autophagy inhibition for pancreatic cancer treatment [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr PR10.

9016 Background: The MAP kinase (MAPK) pathway is of critical importance for keratinocyte proliferation and maturation and is essential for epidermal homeostasis. Occurrence of hyperproliferative skin lesions including keratoacanthomas (KA) and cuSCC are considered a class effect of BRAFi [Anforth 2012, Chu 2012, Mattei 2012]. These effects, as well as promotion of pre-existing RAS-driven malignancies, may be caused by paradoxical activation of the MAPK pathway downstream of BRAF in wild-type BRAF cells. As MEK inhibition blocks downstream MAPK signaling, it was hypothesized that addition of a MEKi to a BRAFi would abrogate these effects [Su, 2012]. Methods: This 4-part phase I/II study enrolled 365 BRAFV600E/Kmutated MM pts in Parts B-D. In part C, 162 pts (BRAFi and MEKi treatment-naïve, ≥ 18 yrs; ECOG PS <2; RECIST measurable disease) were randomized to D monotherapy 150mg BID (D mono) vs. the combination of D (150 mg BID) and T (1 mg or 2 mg QD). Primary endpoints included safety and efficacy. Occurrence of cuSCC (including KA) across three arms in Part C and secondary malignancies with D+T across all Parts are provided below. Results: The difference in incidence of cuSCC between D mono and the D+T (150/1) was statistically significant, whereas the difference in incidence between D mono and D+T (150/2) was not. The median time to onset of cuSCC was 30 days in D mono compared to 282 and 152 days with D+T (150/1 and 150/2, respectively). Of 365 pts who received D+T, 2 (<1%) cases of new cancers (colorectal and gliobastoma) and 2 (<1%) cases of new primary malignant melanoma were reported. Conclusions: These data support the experimental hypothesis that the occurrence of cuSCC (including KA) can be substantially reduced and delayed by the addition of a MEKi to BRAFi therapy. Clinical trial information: NCT01072175. [Table: see text]

9005 Background: Dual inhibition of the MAP kinase (MAPK) pathway with dabrafenib (D) and trametinib (T) in combination has demonstrated clinical benefit compared to D alone in a randomized Phase II trial in V600 BRAF-mutant MM pts, thus delaying the development of BRAFi resistance. Little is known about the efficacy of D + T after BRAFi resistance has been acquired. This analysis evaluates the ability of D + T combination to treat acquired resistance compared to the D + T combination as first-line treatment. Methods: These data from a phase I/II study include 1. BRAFi-resistant group: pts who received 150/2 D+T in Part B (n=26) and Part C (n=43) following progression on BRAFi monotherapy (mono); 2. BRAFi-naïve group: pts who received initial 150/2 D+T in Part B (n=24) and Part C (n=54). Results: Baseline characteristics (ECOG PS, M staging, LDH) were similar across all groups.In the Part B BRAFi-resistant group, 93% of pts previously received D or vemurafenib and all pts received D prior to D+T in Part C. In BRAFi-resistant group, prior best response of CR/PR (38%, 56%), SD (35%, 27%), PD (27%, 7%) was observed in Parts B and C respectively. In BRAFi-resistant group, the ORR and PFS with D+T was lower than initial D+T in BRAFi-naive group. Median duration of response (DoR) in BRAFi-resistant group cannot be calculated due to small no. of pts responding. Median DoR for BRAFi-naïve pts was 11.3 mo and 10.5 mo in Parts B and C respectively. In Part C, the 12-mo overall survival rates in BRAFi-naïve (150/2) pts was 79% vs 70% for pts initially on D mono, despite 80% pts crossing over to D+T combination. Conclusions: The clinical activity for 150/2 D+T combination is consistently superior in BRAFi-naive group vs BRAFi-resistant group in both Parts B and C. Dual MAPK blockade can delay clinical resistance to BRAF inhibition. However, once BRAFi resistance has occurred, the combination of BRAFi + MEKi is far less effective. Clinical trial information: NCT01072175. [Table: see text]

Abstract Vascular smooth muscle cells (VSMCs) in the normal arterial media continually express contractile phenotypic markers which are reduced dramatically in response to injury. Tripartite motif‐containing proteins are a family of scaffold proteins shown to regulate gene silencing, cell growth, and differentiation. We here investigated the biological role of tripartite motif‐containing 28 (TRIM28) and tripartite motif‐containing 27 (TRIM27) in VSMCs. We observed that siRNA‐mediated knockdown of TRIM28 and TRIM27 inhibited platelet‐derived growth factor (PDGF)‐induced migration in human VSMCs. Both TRIM28 and TRIM27 can regulate serum response element activity and were required for maintaining the contractile gene expression in human VSMCs. At the same time, TRIM28 and TRIM27 knockdown reduced the expression of PDGF receptor‐β (PDGFRβ) and the phosphorylation of its downstream signaling components. Immunoprecipitation showed that TRIM28 formed complexes with TRIM27 through its N‐terminal RING‐B boxes‐Coiled‐Coil domain. Furthermore, TRIM28 and TRIM27 were shown to be upregulated and mediate the VSMC contractile marker gene and PDGFRβ expression in differentiating human bone marrow mesenchymal stem cells. In conclusion, we identified that TRIM28 and TRIM27 cooperatively maintain the endogenous expression of PDGFRβ and contractile phenotype of human VSMCs.

e14507 Background: Regorafenib, an oral multikinase inhibitor of VEGFR2/3, PDGFRb, KIT, FGFR, RET, RAF and TIE2, is efficacious in refractory mCRC but its mechanism of action is unclear and predictive biomarkers are lacking. Methods: We assessed tumor and circulatory biomarkers in a phase 2 study of regorafenib in refractory mCRC patients. Regorafenib was administered orally at 160mg/d for 3 out of 4 weeks. Post cycle 2 response was assessed by RECIST 1.1. Subjects were scheduled for FDG PET-CT scans (pre + D15) and paired core needle tumor biopsies for IHC analysis (pre + D21) in cycle 1. Archival tumor mutations were evaluated using Sequenom MassARRAY OncoCarta Panel V1.0 assay. Results: 35 patients were treated; 49% received > 4 prior therapies and 43% had prior bevacizumab. Median PFS was 3.45 mths (95% CI: 3.40-3.49), ORR was 3% and disease control rate [DCR] (PR + SD at 8 wks) was 57%. Early PET responses (EORTC criteria) were seen in 49%, but did not predict for DCR (p=1.0). Fatigue, hand foot skin reaction (HFSR), voice change and diarrhea occurred in > 30% of subjects. Grade 3-5 toxicities occurred in 46%, the commonest being HFSR and rash (17% each). Median relative dose intensity was 92%; 43% required > 1 dose reduction, 60% required > 1 dose interruption. KRAS (29%), BRAF (9%), EGFR (9%), NRAS (6%) KIT (3%), PIK3CA (3%), PDGFRA (3%) and CDK (3%) mutations were detected in archival tumors. None predicted for ORR or DCR; PFS was identical in KRAS mutant vs wt patients (3.45 mths, p=0.39) and similar in BRAF mutant vs wt patients (3.48 vs 3.45 mths, p=0.10). The patient with the longest PFS (12.6 mths) had a BRAF mutation. Amongst the 10 paired tumor samples available, IHC markers upregulated in >50% cases were pMEK, pERK, pJun and pJNK, whilst those downregulated/ unchanged in >50% were pKIT, pVEGFR2, CD31 [vascular endothelial cells (ECs)] and podoplanin (lymphatic ECs). The greatest change was observed in podoplanin expression, corresponding to a 60% reduction in lymphatic vessel density. Conclusions: FDG-PET responses in cycle 1 did not predict for regorafenib clinical benefit in mCRC patients. Targeting lymphatic/vascular ECs in the tumor microenvironment may be a more significant antitumor mechanism of regorafenib than MAP kinase pathway inhibition. Clinical trial information: NCT01189903.

5028 Background: Edmonston vaccine strains of MV have significant antitumor activity against ovarian cancer xenografts (Peng et al, Cancer Res, 2002). Oncolytic selectivity is due to overexpression of the MV CD46 receptor in ovarian cancer cells. Furthermore, engineering the virus to express the marker peptide CEA (MV-CEA) allows real time monitoring of viral gene expression/propagation in vivo. Methods: We are conducting a Phase I trial of MV-CEA in patients (pts) with recurrent, taxol and platinum refractory, ovarian or primary peritoneal carcinoma. Eligible pts should have protective anti-MV antibody (ab) titers and normal CEA levels. A standard phase I cohorts of three statistical design is employed. MV-CEA is administered IP via a port-a-cath, q 4 wks for up to 6 cycles. Results: To date, 12 pts have received viral doses from 103 to 106 TCID50. No dose-limiting toxicity has been observed. Most common toxicities included grade 1–2 nausea (4 pts); grade 1–2 fatigue (4 pts); grade 1 fever (3 pts); grade 1 abdominal pain (2 pts). One pt had grade 2–3 arthralgias in cycles 4–6. There was no treatment induced immunosuppression as assessed by DTH, CD4, CD8, immunoglobulin and complement levels, no significant increase in the titers of anti-MV abs in serum or ascites in response to treatment, and no development of anti-CEA abs. Viral genomes were detected in the peripheral blood mononuclear cells of 2 asymptomatic pts by QRT-PCR. No CEA elevation in the serum was observed in the dose range tested, and there was no viral shedding in urine or mouth gargle specimens. Testing of pt tumor samples for CD46 by IHC demonstrated overexpression of the target receptor in 7/8 pts. Best objective response was stable disease (2 - 9 mo duration) in 5 pts, while 3 pts had significant decrease in CA125 levels, of 44%, 72%, and 78%, respectively. Conclusions: In this first human application of an engineered oncolytic MV strain, we have observed excellent tolerance after repeat IP administration of the virus. Despite the low doses employed so far, there is early evidence of biologic activity. Dose escalation continues to the target dose of 109 TCID50. No significant financial relationships to disclose.

Abstract Importance: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections outbreak in China is now a global issue. There is only a limited understanding of the clinical characteristics of patients with SARS-CoV-2 infections is available.Objective:To describe the characteristics, management strategies, and outcomes of critically ill patients with SARS-CoV-2 infection.Design, Setting, and Patients: This is aretrospective, multi-center case series of 50 critically ill patients with confirmed SARS-CoV-2 infection who were admitted at Zhongnan Hospital of Wuhan University and Wuhan Pulmonary Hospital in Wuhan, China, from January 8 to February 9, 2020.Exposures:Documented Corona Virus Disease, 2019 (COVID-19).Main Outcome Measures: Demographic, clinical, laboratory, imaging data were collected along with management strategies, complications and outcomes of enrolled individuals. Results Fifty critically ill patients with SARS-CoV-2 infections were enrolled. Their median age was 62 (range, 29-92) [IQR,49.5-69.0] years, 68% were male, and 28 (56%) patients had comorbidities, the most common being hypertension. In this cohort, 20(40%) patients survived ,16(32%) patients died, and the rest remained hospitalized. The invasive mechanical ventilator was used in 36(72%) patients with 15(30%) of them requiring prone positioning, and 17(34%) switched to ECMO. The compliance scores of lungs (Cstat)on the day of ICU admission among survivors were higher than those in non-survivors [42.0(18.0-47.0), vs. 19.5(14.0-24.2), p=0.038].The blood IL-6 levels and neutrophils counts at the first day of ICU admission were significantly higher in non-survivors compared to survivors [123.7(85.3-228.8), vs. 20.2(6.8-67.2) ng/ml, p=0.025 for IL-6, and 20.2(6.8-67.2) vs. 4.01(1.99-7.05) × 10⁹/L, p=0.02 for neutrophils counts].The heart rates, PaCO2, lung injury scale (LIS), and positive end-expiratory pressure levels were constantly higher for 10 days in non-survivors than those who survived (p<0.05). The frequency of vasopressor uses and neuromuscular blockers was higher in non-survivors from day 1 to day 10 compared to survivors (p<0.05). In the whole cohort, the most common complications were ARDS (97%), shock (44%), arrhythmia (38%), acute cardiac injury (26%), and acute kidney injury (22%). A secondary bacterial infection was noted in 17(34%) patients. Univariate analysis indicated that lower lung complianceand higher neutrophil counts at the day of ICU admission were related to higher mortality (p-0.03, and 0.04, respectively)ConclusionWe demonstrated that SARS-CoV-2 infection-related critical illness predominantly affected old individuals with comorbidities and characterized by severe hypoxemic respiratory failure, often requiring prolonged mechanical ventilation and rescue therapies. Low lung compliance and persistently elevated PaCO2 indicated poor outcomes.

Introduction: Nonconvulsive seizures (NCSs) are common in critically ill adult patients with acute neurologic conditions. However, the effect of NCSs on patient outcome remains unclear. In this study, we aimed to determine the effect of NCSs on short-term outcome and to assess the clinical and EEG factors associated with NCSs. Methods: We retrospectively identified 219 adult patients from the EEG reporting system who underwent continuous EEG (cEEG) monitoring between January 2018 and June 2018. Patients with anoxic brain injury were excluded from the study. Clinical, laboratory, and EEG data were reviewed to determine potentially predictive factors of NCSs. The impact of NCSs on in-hospital mortality, length of stay, and disability on discharge was measured; an modified Rankin scale of three or greater was considered disabled. Results: Of the 219 patients included in our study, a total of 14% (n = 31) had NCSs on continuous EEG, of which 42% (n = 13) had their first seizure discharge recorded during the first hour of continuous EEG monitoring. The presence of clinical seizures before continuous EEG (odds ratio = 1.787; 95% confidence interval = 1.197–2.667, P = 0.0045), history of epilepsy (odds ratio = 1.508; 95% confidence interval = 1.027–2.215, P = 0.035), and comatose state (29 vs. 16%; P = 0.0006) were associated with NCSs. Among EEG characteristics, the presence of interictal epileptiform discharges (P < 0.0001), lateralized rhythmic delta activity (P = 0.02), and lateralized periodic discharges (P < 0.0001) were associated with NCSs. Nonconvulsive seizures were significantly associated with longer in-hospital stay (23.68 ± 24.84 vs. 17.14 ± 20.52; P = 0.036) and disability on discharge (87% [n = 27] vs. 13% [n = 4], P = 0.02). However, there was no significant association between NCS and in-hospital mortality (9.6% [n = 3] vs. 10.6% [n = 20]; P = 0.1). Conclusions: Nonconvulsive seizures are associated with longer in-hospital stay and disability on discharge but not with in-hospital mortality in adult patients.

Despite the success of chimeric antigen receptor T (CART) cell therapy, it is limited by 1) lower rates of durable responses related to inadequate CART cell expansion and trafficking to tumor sites and 2) development of life-threatening complication such as cytokine release syndrome (CRS). Development of a strategy to efficiently and robustly image and track CART cells in the clinic would allow the in vivo characterization of T cell expansion and trafficking to tumor sites as well as the development of strategies to potentially overcome these limitations. The sodium iodide symporter (NIS) is a characterized and sensitive reporter system that has been used for cell imaging in the clinic. We hypothesized that the incorporation of NIS into CART cells would be a sensitive and efficient way to assess CART cell expansion, trafficking, and toxicity. To test our hypothesis, we used two CART cell constructs that are characterized in preclinical models and studied extensively in the clinic: CART19 (41BB costimulated) and BCMA-CART cells (41BB costimulated). First, we generated NIS+CART19 and NIS+BCMA-CART cells through dual transduction of lentiviral vectors (Fig A) and revealed the exclusive 125I uptake by these NIS+CARTs and its inhibition by the NIS inhibitor KClO4in vitro (Fig B). We then analyzed T cell functions of NIS+CART cells. Here, NIS+CART19 or CART19 cells were cultured with the CD19+ acute lymphoblastic leukemia (ALL) cell line NALM6. There was no difference in CART cell cytotoxicity (Fig C), proliferation, or cytokine production (not shown) between NIS+CART19 and CART19. This indicates that the incorporation of NIS into CART cells does not impair their antitumor activity. Next, we evaluated the sensitivity of NIS+CART19 cell detection by TFB-PET in vivo; imaging was performed using an Inveon TFB-PET/CT scanner. Mice received 250 μCi 18F-TFB 45 minutes prior to image acquisition. NIS+CART cells were detectable with TFB-PET when cells were subcutaneously injected at a dose of 1.25x106 cells (Fig D). Having demonstrated that the incorporation of NIS in CART cells provides a sensitive way of their detection by TFB-PET and does not interfere with their effector functions, we tested its efficiency to assess CART cell trafficking in vivo, using multiple myeloma (MM) xenografts. Here, immunocompromised NOD-SCID-ɣ-/- (NSG) mice were engrafted with the BCMA+OPM2 MM cell line (1x106 IV). After engraftment, the tumor burden was assessed by bioluminescence imaging (BLI) and mice were randomized to receive 1) BCMA-CART or 2) NIS+BCMA-CART cells (5x106 IV). Mice were then serially imaged for 1) bioluminescence as a measure of disease burden, and 2) with TFB-PET to assess CART cell expansion and trafficking. As expected, BLI demonstrated that MM predominantly engrafts in bones (Fig E). TFB-PET confirmed trafficking of the NIS+BCMA-CART cells to the bones, corresponding to the areas involved by MM based on BLI (Fig E, right). Both BCMA-CART and NIS+BCMA-CART cells exhibited similarly potent antitumor activity in this model (not shown). Finally, we aimed to explore whether TFB-PET can detect CART massive expansion in vivo and predict the development of CRS. Here, we used an established CRS model in our laboratory. NSG mice were engrafted with patient derived relapsed ALL blasts (5x106 IV). Engraftment was confirmed by peripheral blood sampling. When the leukemic burden is &gt;10 CD19+ cell/µl, mice were treated with either high dose NIS+CART19 cells (5x106 IV) or PBS control. One week after NIS+CART19 cell treatment, mice developed muscle weakness, hunched bodies, and weight loss (Fig F), which correlate with an extreme elevation of cytokines (Sterner et al. Blood 2018). TFB-PET revealed a significant uptake in the bone marrow, spleen, liver, and lungs (Fig G) of the diseased mice but not control mice. Mice were then euthanized, and tissues were harvested. Flow cytometric analysis confirmed an extensive infiltration of CART cells in the liver and spleen. This demonstrates the ability of TFB-PET to detect NIS+CART cell expansion in vivo, correlating with the development of CRS. In summary, our results robustly show that the incorporation of NIS into CART cells provides a sensitive, clinically applicable platform to image CART cells using TFB-PET and to assess their expansion, trafficking to tumor sites, and the development of CRS. These studies illuminate a novel way to noninvasively assess CART cell functions in vivo. Figure Disclosures Sakemura: Humanigen: Patents & Royalties. Suksanpaisan:Imanis: Employment. Cox:Humanigen: Patents & Royalties. Parikh:Janssen: Research Funding; AstraZeneca: Honoraria, Research Funding; Pharmacyclics: Honoraria, Research Funding; MorphoSys: Research Funding; AbbVie: Honoraria, Research Funding; Acerta Pharma: Research Funding; Ascentage Pharma: Research Funding; Genentech: Honoraria. Kay:Agios: Other: DSMB; Infinity Pharmaceuticals: Other: DSMB; Celgene: Other: Data Safety Monitoring Board; MorphoSys: Other: Data Safety Monitoring Board. Peng:Imanis: Equity Ownership. Russell:Imanis: Equity Ownership. Kenderian:Kite/Gilead: Research Funding; Lentigen: Research Funding; Morphosys: Research Funding; Tolero: Research Funding; Humanigen: Other: Scientific advisory board , Patents & Royalties, Research Funding; Novartis: Patents & Royalties, Research Funding.