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31 Background: T-cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domains (TIGIT) inhibitor in combination with an anti-programmed cell death protein 1 (PD-1) antibody has shown antitumor activity in solid tumors. AdvanTIG-105 (NCT04047862) is a phase 1/1b open-label study designed to assess the safety and preliminary antitumor activity of OCI, an anti-TIGIT monoclonal antibody (mAb), + TIS, an anti-PD-1 mAb, in pts with unresectable, locally advanced or metastatic solid tumors. In the dose-escalation part, OCI + TIS was well tolerated with preliminary antitumor activity observed, and the recommended phase 2 dose (RP2D) of OCI 900 mg intravenously (IV) every three weeks (Q3W) + TIS 200 mg IV Q3W was established. We report results from the dose-expansion part (GC/GEJC Cohort 9) of the AdvanTIG-105 study. Methods: Eligible pts had histologically/cytologically confirmed stage IV GC/GEJC. Pts were excluded if they had squamous cell, undifferentiated or other histological types of GC, had GC/GEJC with positive HER2 expression, or if they had received any prior therapy for metastatic disease. Pts received either the RP2D of OCI + TIS with oxaliplatin + capecitabine Q3W for 6 cycles (C), followed by maintenance therapy with the RP2D of OCI + TIS, + capecitabine Q3W, or the RP2D of OCI + TIS with cisplatin + 5-fluorouracil Q3W for 6 C. Treatment continued until disease progression, intolerable toxicity, or withdrawal of consent. The primary endpoint was investigator-assessed overall response rate (ORR) per RECIST v1.1. Secondary endpoints included progression-free survival (PFS), duration of response (DoR), disease control rate (DCR) per RECIST v1.1, and safety. Results: As of September 29, 2022, 60 pts with a median age of 61.5 years (range 35-82) were enrolled; 59 were efficacy evaluable. Median study follow-up was 31.1 weeks (range 1.4-78.4). ORR was 50.8% (95% CI: 37.5, 64.1); DCR was 84.7% (95% CI: 73.0, 92.8) with a median DoR of 8.1 months (95% CI: 4.5, not evaluable [NE]). Median PFS was 8.2 months (95% CI: 5.8, NE). In a subgroup analysis, ORR in pts with PD-L1 tumor area positivity (TAP) score ≥5% (n=27) was 59.3% (95% CI: 38.8, 77.6), and 50.0% (95% CI: 30.7, 69.4) in pts with PD-L1 TAP <5% (n=28). All 60 pts reported ≥1 treatment-emergent adverse event (TEAE), the most common being anemia (43.3%) and platelet count decreased (41.7%). In total, 43 pts (71.7%) had ≥grade 3 TEAEs and 28 (46.7%) had serious adverse events. TEAEs leading to discontinuation of TIS and OCI occurred in 5 (8.3%) pts. TEAEs led to death in 2 (3.3%) pts; one event (neutropenic sepsis) was related to chemo, while the other (pulmonary embolism) was not treatment related. Conclusions: OCI 900 mg + TIS 200 mg + chemo was generally well tolerated and showed encouraging antitumor activity in pts with stage IV GC/GEJC. Clinical trial information: NCT04047862 .

27 Background: Cholangiocarcinoma (CCA) is a devastating cancer with few effective treatment options. We have previously discovered LCK can activate AXL, a TAM receptor tyrosine kinase (RTK), by phosphorylation of AXL-Y866 ( J Hepatol 2022). AXL is known to confer therapeutic resistance to solid cancers. However, the role of AXL in CCA, and the impact of AXL-Y866 activation by LCK still remains to be elucidated. Here, we investigated the significance of AXL expression, signaling, and activation by LCK on Y866. Methods: We first evaluated the expression levels of AXL in CCA and its association with patient outcome using The Cancer Genome Atlas (TCGA) dataset. Next, to evaluate whether AXL inactivation sensitizes CCA cells to gemcitabine and cisplatin (GC), AXL downregulation was achieved via siRNA approach and the selective AXL inhibitor bemcentinib (Bem) using human CCA cell lines, HuCCT1 and RBE, and murine SB-1. We examined 50% inhibitory concentration (IC50) value on GC with or without AXL knockdown (KD) using cell viability assay. Then we assessed the efficacy of the combination of GC and Bem utilizing Calcusyn software and apoptosis by Annexin V assay. I n vivo efficacy was assessed using both a patient derived CCA xenograft and SB-1 a syngeneic model of CCA treated with vehicle, GC, Bem, or the combination. Next, we defined the interactome of wildtype AXL- Y866 compared to AXL-Y866F using biotin proximity labelling methods (BioID), validation of downstream target proteins using Western blot (WB), and a functional study with AXL-/- cells reconstituted with either AXL WT, or AXL Y866F. Results: In TCGA cohorts, AXL transcripts are more abundant than in normal adjacent liver, and higher levels are correlated with worse clinical outcome. In in vitro study, IC50 values of GC decreased after AXL KD. Synergistic effects were observed in the combination. The combination caused increased apoptosis compared to other treatments. In the in vivo studies, the combination suppressed tumor growth and the Ki67 levels, and the phosphorylation levels of PEAK1 decreased in the combination group compared to other groups. In BioID experiments, among the 222 proteins which were detected in both AXL WT and AXL Y866F interactomes, PEAK1 kinase, which localizes to actin cytoskeleton and focal adhesions, was most altered when Y866 was inactivated by the Y866F mutation. In gene ontology analysis, cell-cell adhesion and focal adhesion related proteins were enriched. In WB, we validated that the phosphorylation of PEAK1 decreased after AXL or LCK knockout (KO) and after Bem treatment in above in vivo study. In cell viability assay, reconstitution of AXL KO cells with WT AXL increased the IC50 to GC while reconstitution with AXL-Y866F did not. Conclusions: AXL inhibition sensitizes CCA cells to cytotoxic chemotherapy in preclinical model. LCK-AXL Y866-PEAK1 signaling axis is a potential target for the treatment of CCA.

136 Background: Studies using International Classification of Diseases (ICD) codes have aimed to characterize the safety profile of cancer therapies in the Real-World Data setting, but this approach has limitations including an inability to illustrate patient journey and offer insights into drug-Adverse Event (AE) causality. Using data from a cohort of ~9000 patients treated with immune checkpoint inhibitors (ICI) at Mayo Clinic, we recently demonstrated the feasibility of applying Augmented Curation (AC), a natural language processing (NLP)-based innovation, on unstructured electronic health record (EHR) data to detect and characterize immune related AEs (irAEs). While the ability to identify and extract clinical details from EHRs has been previously demonstrated, our approach focuses on applying these techniques to identify implied textual causality of drug-event pairs. This study aims to build upon our prior findings and compare the accuracy, speed, and resource savings enabled by AC analysis versus manual review of patient notes. Methods: We compared the prevalence of adrenal insufficiency, colitis, and hypophysitis (A.C.H) among ICI patients at Mayo Clinic using ICD codes and AC which leverages SciBERT to perform scientific NLP tasks. AC models trained to identify drug-adverse event relationships were used to assess irAEs and subsequent treatments and demonstrated strong performance with F1 scores of 0.85. Manual curation of relevant clinical data, i.e. medications and adverse events, was employed to create a “gold standard” A.C.H. cohort. Time required for manual review compared to AC was documented for overall comparison. Corticosteroid/immunosuppressant use and ICI discontinuations were used as proxies of severity. Results: In our cohort, 540 unique patients experienced at least one of the A.C.H. irAEs. A.C.H patients were found to receive corticosteroids for their respective irAE 79% of the time and discontinued the ICI due to the irAE 7.7% of the time. 6.1% of Colitis patients were treated with a 2L immunosuppressant. Similar to the previous study, AC showed higher sensitivity, PPV and NPV compared to ICD codes alone within the A.C.H. cohort. Sentence extraction and entity classification using AC models on all 9,000-patients took ~10 minutes, whereas manual review of this cohort would take roughly 9 weeks (~10 minutes per patient). Conclusions: The results from this study reinforce that AC models are a valuable tool to comprehensively extract information and to impute relationships between entities, such as therapies and AEs. The AC models demonstrated better accuracy at a much greater speed compared to manual review of patient EHRs. Leveraging AC models provides the ability to manipulate unstructured clinical text married to structured EHR data at scale while minimizing need for manual curation.

Background The tumor lysate, particle-loaded, dendritic cell (TLPLDC) vaccine is made by ex vivo priming matured autologous dendritic cells (DCs) with yeast cell wall particles (YCWPs) loaded with autologous tumor lysate (TL). The tumor lysate, particle only (TLPO) vaccine uses autologous TL-loaded YCWPs coated with silicate for in vivo DC loading. Here we report the 36-month prespecified analyses of this prospective, randomized, double-blind trial investigating the ability of the TLPO and TLPLDC (±granulocyte-colony stimulating factor (G-CSF)) vaccines to prevent melanoma recurrence in high-risk patients. Methods Patients with clinically disease-free stage III/IV melanoma were randomized 2:1 initially to TLPLDC versus placebo (n=124) and subsequently TLPO versus TLPLDC (n=63). All patients were randomized and blinded; however, the placebo control arm was replaced in the second randomization scheme with another novel vaccine; some analyses in this paper therefore reflect a combination of the two randomization schemes. Patients receiving the TLPLDC vaccine were further divided by their method of DC harvest (with or without G-CSF pretreatment); this was not randomized. The use of standard of care checkpoint inhibitors was not stratified between groups. Safety was assessed and Kaplan-Meier and log-rank analyses compared disease-free (DFS) and overall survival (OS). Results After combining the two randomization processes, a total of 187 patients were allocated between treatment arms: placebo (n=41), TLPLDC (n=103), or TLPO (n=43). The allocation among arms created by the addition of patients from the two separate randomization schemes does not reflect concurrent randomization among all treatment arms. TLPLDC was further divided by use of G-CSF in DC harvest: no G-CSF (TLPLDC) (n=47) and with G-CSF (TLPLDC+G) (n=56). Median follow-up was 35.8 months. Only two patients experienced a related adverse event ≥grade 3, one each in the TLPLDC+G and placebo arms. DFS was 27.2% (placebo), 55.4% (TLPLDC), 22.9% (TLPLDC+G), and 60.9% (TLPO) (p<0.001). OS was 62.5% (placebo), 93.6% (TLPLDC), 57.7% (TLPLDC+G), and 94.6% (TLPO) (p=0.002). Conclusions The TLPO and TLPLDC (without G-CSF) vaccines were associated with improved DFS and OS in this clinical trial. Given production and manufacturing advantages, the efficacy of the TLPO vaccine will be confirmed in a phase 3 trial. Trial registration number NCT02301611 .

Abstract Background Although comorbidities are risk factors for recurrent Clostridioides difficile infection (rCDI), many clinical trials exclude patients with medical conditions such as malignancy or immunosuppression. In a phase 3, double-blind, placebo-controlled, randomized trial (ECOSPOR III), fecal microbiota spores, live (VOWST, Seres Therapeutics; hereafter “VOS,” formerly SER-109), an oral microbiota therapeutic, significantly reduced the risk of rCDI at week 8. We evaluated the efficacy of VOS compared with placebo in patients with comorbidities and other risk factors for rCDI. Methods Adults with rCDI were randomized to receive VOS or placebo (4 capsules daily for 3 days) following standard-of-care antibiotics. In this post hoc analysis, the rate of rCDI through week 8 was assessed in VOS-treated participants compared with placebo for subgroups including (i) Charlson comorbidity index (CCI) score category (0, 1–2, 3–4, ≥5); (ii) baseline creatinine clearance (&lt;30, 30–50, &gt;50 to 80, or &gt;80 mL/minute); (iii) number of CDI episodes, inclusive of the qualifying episode (3 and ≥4); (iv) exposure to non-CDI-targeted antibiotics after dosing; and (v) acid-suppressing medication use at baseline. Results Of 281 participants screened, 182 were randomized (59.9% female; mean age, 65.5 years). Comorbidities were common with a mean overall baseline age-adjusted CCI score of 4.1 (4.1 in the VOS arm and 4.2 in the placebo arm). Across all subgroups analyzed, VOS-treated participants had a lower relative risk of recurrence compared with placebo. Conclusions In this post hoc analysis, VOS reduced the risk of rCDI compared with placebo, regardless of baseline characteristics, concomitant medications, or comorbidities.

Abstract Background Powassan virus (POWV) is an emerging arthropod-borne flavivirus, transmitted by Ixodes spp. ticks, which has been associated with neuroinvasive disease and poor outcomes. Methods A retrospective study was conducted at Mayo Clinic from 2013 to 2022. We included clinical and epidemiologic data of probable and confirmed neuroinvasive POWV cases. Results Sixteen patients with neuroinvasive POWV were identified; their median age was 63.2 years, and 62.5% were male. Six patients presented with rhombencephalitis, 4 with isolated meningitis, 3 with meningoencephalitis, 2 with meningoencephalomyelitis, and 1 with opsoclonus myoclonus syndrome. A median time of 18 days was observed between symptom onset and diagnosis. Cerebrospinal fluid analysis showed lymphocytic pleocytosis with elevated protein and normal glucose in the majority of patients. Death occurred within 90 days in 3 patients (18.8%), and residual neurologic deficits were seen in 8 survivors (72.7%). Conclusions To our knowledge, this is the largest case series of patients with neuroinvasive POWV infection. We highlight the importance of a high clinical suspicion among patients who live in or travel to high-risk areas during the spring to fall months. Our data show high morbidity and mortality rates among patients with neuroinvasive disease.

Abstract Background Although fecal microbiota transplant has been used to prevent recurrent Clostridioides difficile infection (rCDI), documented pathogen transmissions highlight inherent safety risks of minimally processed stool. We describe manufacturing processes for fecal microbiota spores, live (VOWST; VOS, formerly SER-109), a microbiota-based oral therapeutic of Firmicutes spores. Methods Bacterial inactivation kill curves were obtained after ethanol exposure for 4 model organisms spiked into process intermediates. Results Bacterial log reduction factors ranged from 6.5 log10 to 7.4 log10 and lysis of spiked organisms occurred rapidly within 30 seconds. Conclusions These experiments demonstrate substantial and rapid inactivation of representative organisms, supporting the potential benefit of VOS manufacturing processes to mitigate risk.

Functional ultrasound (fUS), an emerging hemodynamic-based functional neuroimaging technique, is especially suited to probe brain activity and primarily used in animal models. Increasing use of pharmacological models for essential tremor extends new research to the utilization of fUS imaging in such models. Harmaline-induced tremor is an easily provoked model for the development of new therapies for essential tremor (ET). Furthermore, harmaline-induced tremor can be suppressed by the same classic medications used for essential tremor, which leads to the utilization of this model for preclinical testing. However, changes in local cerebral activities under the effect of tremorgenic doses of harmaline have not been completely investigated. In this study, we explored the feasibility of fUS imaging for visualization of cerebral activation and deactivation associated with harmaline-induced tremor and tremor-suppressing effects of propranolol. The spatial resolution of fUS using a high frame rate imaging enabled us to visualize time-locked and site-specific changes in cerebral blood flow associated with harmaline-evoked tremor. Intraperitoneal administration of harmaline generated significant neural activity changes in the primary motor cortex and ventrolateral thalamus (VL Thal) regions during tremor and then gradually returned to baseline level as tremor subsided with time. To the best of our knowledge, this is the first functional ultrasound study to show the neurovascular activation of harmaline-induced tremor and the therapeutic suppression in a rat model. Thus, fUS can be considered a noninvasive imaging method for studying neuronal activities involved in the ET model and its treatment.

The prevalence of invasive candidiasis caused by non-Candida albicans has rapidly increased. Candida glabrata (Nakaseomyces glabrata) is an important pathogen associated with substantial mortality. Our study examined the antifungal temporal susceptibility of C. glabrata and cross-resistance/non-wild-type patterns with other azoles and echinocandins. Laboratory data of all adult patients with C. glabrata isolated from clinical specimens at the Mayo Clinic, Rochester, from 2012 to 2022 were collected. Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints were used. We obtained 1046 C. glabrata isolates from 877 patients. Using CLSI and EUCAST breakpoints, 187 (17.9%) isolates and 256 (24.5%) isolates were fluconazole-resistant, respectively. Focusing on C. glabrata bloodstream infections, fluconazole-resistance ranged from 16 to 22%. Among those 187 fluconazole-resistant isolates, 187 (100%) and 184 (98.4%) isolates were also voriconazole and posaconazole non-wild-type, respectively, with 97 (51.9%) isolates deemed non-wild type for itraconazole. The fluconazole susceptibility pattern has not changed over the past decade. The proportion of fluconazole-resistant C. glabrata is relatively high, which could be due to the complexity of patients and fluconazole exposure. Itraconazole appears to be a compelling step-down therapy for fluconazole-resistant C. glabrata, given the high proportion of wild-type isolates. Further research to examine clinical outcomes is warranted.