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Because Notch signaling is implicated in colon cancer tumorigenesis and protects from apoptosis by inducing pro-survival targets, it was hypothesized that inhibition of Notch signaling with gamma-secretase inhibitors (GSIs) may enhance the chemosensitivity of colon cancer cells. We first show that the Notch-1 receptor and its downstream target Hes-1 is upregulated with colon cancer progression, similar to other genes involved in chemoresistance. We then report that chemotherapy induces Notch-1, as oxaliplatin, fluorouracil (5-FU), or SN-38 (the active metabolite of irinotecan), induced Notch-1 Intracellular Domain (NICD) protein and activated Hes-1. Induction of NICD was caused by an increase in the gamma-secretase protein subunits, nicastrin and presenilin-1, as suppression of nicastrin with small interfering RNA (siRNA) prevented NICD induction after oxaliplatin. Subsequent, inhibition of Notch-1 signaling with a sulfonamide GSI (GSI34) prevented the induction of NICD by chemotherapy and blunted Hes-1 activation. Blocking the activation of Notch signaling with GSI34 sensitized cells to chemotherapy and was synergistic with oxaliplatin, 5-FU, and SN-38. This chemosensitization was mediated by Notch-1, as inhibition of Notch-1 with siRNA, enhanced chemosensitivity whereas overexpression of NICD increased chemoresistance. Downregulation of Notch signaling also prevented the induction of pro-survival pathways, most notably PI3K/Akt, after oxaliplatin. In summary, colon cancer cells may upregulate Notch-1 as a protective mechanism in response to chemotherapy. Therefore, combining GSIs with chemotherapy may represent a novel approach for treating metastatic colon cancers by mitigating the development of chemoresistance.

9503 Background: The immunomodulatory receptor TIGIT is a novel inhibitory immune checkpoint present on activated T cells and NK cells in multiple cancers, including NSCLC. In a phase I study (GO30103), co-inhibition of TIGIT and PD-L1 signaling with tira plus atezo in CIT-naïve PD-L1 positive NSCLC potentially improved overall response rates (ORR) compared to historical ORR with PD-L1/PD-1 inhibitors. We conducted this phase II trial to confirm the efficacy and safety of tira plus atezo (TA) compared to placebo plus atezo (PA) in 1L NSCLC (GO40290, NCT NCT03563716). Methods: This prospective, randomized, double-blind, placebo-controlled trial enrolled patients (pts) with chemotherapy-naïve PD-L1+ (TPS ≥ 1% by 22C3 IHC pharmDx Dako assay) locally advanced or metastatic NSCLC with measurable disease, ECOG PS 0-1, and without EGFR or ALK alterations. Pts were randomized 1:1 to TA (tira 600 mg IV plus atezo 1200 mg IV) or PA (placebo plus atezo 1200 mg IV) on day 1 of every 3-week cycle. Stratification factors were PD-L1 status (TPS ≥ 50% vs TPS 1-49%), histology, and tobacco history. Co-primary endpoints were investigator assessed ORR and PFS, and additional endpoints were duration of response (DOR), OS, and safety. Exploratory endpoints were the effect of PD-L1 status on ORR and PFS. Results: 135 pts were randomized to PA (n = 68) or TA (n = 67). At primary analysis (30 Jun 2019), TA improved ORR and median PFS (mPFS) compared to PA, with median follow-up of 5.9 mo. In the safety population (68 in PA, 67 in TA), treatment-related AEs (TRAEs) occurred in 72% (PA) and 80.6% (TA); Grade ≥3 TRAEs occurred in 19.1% (PA) and 14.9% (TA). AEs leading to treatment withdrawal occurred in 10.3% (PA) and 7.5% (TA). Clinical trial information: NCT03563716 . With an additional six months of follow-up since the primary analysis (2 Dec 2019, median follow-up of 10.9 mo), improvement in ORR and mPFS was maintained in ITT for TA (37.3% [25.0, 49.6] and 5.6 mo [4.2, 10.4]) vs PA (20.6% [10.2, 30.9] and 3.9 mo [2.7, 4.5]). The safety profile remained tolerable. Conclusions: Treatment with TA compared to PA showed clinically meaningful improvement in ORR and PFS in ITT. The safety profile of TA was similar to PA. [Table: see text]

Background: Cardiopulmonary resuscitation (CPR) is an important advance directive (AD) topic in patients with progressive cancer; however such discussions are challenging. Objective: This study investigates whether video educational information about CPR engenders broader advance care planning (ACP) discourse. Methods: Patients with progressive pancreas or hepatobiliary cancer were randomized to an educational CPR video or a similar CPR narrative. The primary end-point was the difference in ACP documentation one month posttest between arms. Secondary end-points included study impressions; pre-and post-intervention knowledge of and preferences for CPR and mechanical ventilation; and longitudinal patient outcomes. Results: Fifty-six subjects were consented and analyzed. Rates of ACP documentation (either formal ADs or documented discussions) were 40% in the video arm (12/30) compared to 15% in the narrative arm (4/26), OR = 3.6 [95% CI: 0.9-18.0], p = 0.07. Post-intervention knowledge was higher in both arms. Posttest, preferences for CPR had changed in the video arm but not in the narrative arm. Preferences regarding mechanical ventilation did not change in either arm. The majority of subjects in both arms reported the information as helpful and comfortable to discuss, and they recommended it to others. More deaths occurred in the video arm compared to the narrative arm, and more subjects died in hospice settings in the video arm. Conclusions: This pilot randomized trial addressing downstream ACP effects of video versus narrative decision tools demonstrated a trend towards more ACP documentation in video subjects. This trend, as well as other video effects, is the subject of ongoing study.

Activation of AKT signaling by PTEN loss or PIK3CA mutations occurs frequently in human cancers, but targeting AKT has been difficult due to the mechanism-based toxicities of inhibitors that target the inactive conformation of AKT. Ipatasertib (GDC-0068) is a novel selective ATP-competitive small-molecule inhibitor of AKT that preferentially targets active phosphorylated AKT (pAKT) and is potent in cell lines with evidence of AKT activation. In this phase I study, ipatasertib was well tolerated; most adverse events were gastrointestinal and grade 1–2 in severity. The exposures of ipatasertib ≥200 mg daily in patients correlated with preclinical TGI90, and pharmacodynamic studies confirmed that multiple targets (i.e., PRAS40, GSK3β, and mTOR) were inhibited in paired on-treatment biopsies. Preliminary antitumor activity was observed; 16 of 52 patients (30%), with diverse solid tumors and who progressed on prior therapies, had radiographic stable disease, and many of their tumors had activation of AKT.

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