Citations

Abstract Triptolide, which was initially extracted from a Chinese medicinal herb, demonstrates potent antitumor, anti-inflammatory, and immunosuppressive properties, yet it is clinically limited due to its poor solubility, bioavailability, and toxicity. Minnelide, a water-soluble analog of triptolide, has potent antiproliferative activity. It is currently in Phase I/II clinical trials for Acute Myeloid Leukemia (AML) and 7 solid tumor indications, including advanced gastrointestinal tumors, pancreatic cancer, and colorectal cancer. To overcome the potential drug resistance and to improve the drug potency as well as to minimize the drug toxicity, we conducted a high throughput screening (HTS) for drug synergy, combining Minnelide with compounds from the LOPAC and/or Prestwick libraries in 3 different cancer cell lines: BxPC3 (pancreatic), HT29 (colon) and SNU5 (gastric). LOPAC and Prestwick libraries consist of drugs approved by FDA and/or drugs that have reached clinical trial stages, representing 2,274 unique compounds in total. After quality control evaluation and data normalization, hits were selected if greater than 20% inhibition was achieved when combined compared with Minnelide alone. A total of 43, 54, and 47 hits were identified for each cell line, representing an average hit rate of 2.1%. We further prioritized the hits by selecting those that were common in two or more cell lines, which resulted in 9 compounds from Prestwick library and 20 compounds from LOPAC library (Harmane is in common between the two libraries). Only 17 compounds were available for purchase for hits confirmation, which was conducted in a similar manner as in primary HTS, except that drugs were tested in a dose-dependent manner instead of a single concentration done in HTS, a duplicated biological run was performed, and a total of 9 cell lines were screened, with 3 cell lines for each tumor type (pancreatic, colon and gastric). IC50 and Combination Index (CI) values for each drug combination were calculated for each cell line. A fold change of 2 or more for the IC50 values and CI value < 1.0 were used for hit selection. In general, colon lines had the most synergistic combinations and gastric had the least. A total of 15 drug candidates were confirmed to have synergistic effect, representing a confirmation rate of 88%, among which 12 drugs demonstrated synergy in >50% of the cell lines tested, with Harmane and Harmine demonstrating synergy in all 9 cell lines tested. In addition, CGS-15943, Amiloride, Naphthalimide, and Idazoxan indicated good synergy with Minnelide in at least 6 out of 9 cell lines. Interestingly, Phenamil, an irreversible inhibitor of amiloride-sensitive Na+ channels, showed synergy in all cell lines tested for pancreatic and colon cancers, but not in gastric cancer cell lines. Overall, our study shed light on potential drug combinations with Minnlide for clinical use. Citation Format: Nanyun Tang, Chris Sereduk, Ashok Saluja, Mohana Velagapudi, Haiyong Han, Daniel D Von Hoff, Hongwei Holly Yin. Drug combination screen to identify novel synergy with Minnelide [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr A142. doi:10.1158/1535-7163.TARG-19-A142

Abstract Background: TNBC is the most aggressive sub-type of breast cancer and has limited targeted therapies. Atezolizumab was recently FDA-approved for patients with advanced PD-L1+ TNBC. In a well-characterized cohort of patients with early-stage TNBC, we used the FDA-approved PD-L1 SP142 companion assay for atezolizumab to score whole tumor sections for PD-L1 expression. We determined the frequency and scoring distribution of PD-L1 in these tumors and evaluated PD-L1 status for associations with clinicopathologic variables and outcomes. Methods: Whole tumor sections from 498 women with surgically-treated, non-(distant) metastatic TNBC (ER/PR <1% & HER2-negative by central review) were semi-quantitatively scored for % of PD-L1-staining tumor cells (TC) or tumor-associated immune cells (IC) (PD-L1 SP142, Ventana, performed in CAP/CLIA-certified clinical laboratory). Per FDA assay guidelines, PD-L1+ tumors were defined as ≥1% of tumor-associated immune cells (IC) staining per tumor area. Baseline clinical characteristics, histopathologic features, Ki-67 proliferative indices (PI), and stromal tumor infiltrating lymphocytes (TILs) were correlated with PD-L1 status. The impact of tumoral PD-L1 status on invasive disease-free survival (IDFS) and overall survival (OS) was assessed using Cox proportional hazards models. Results: The majority of tumors were pT1-T2 (95%), pN0-1 (85%), and grade 3 (90%) with Ki-67 >15% (80%). 228/498 (46%) tumors were PD-L1+, distributed as IC score 1-5%: 21%, 6-10%: 13%, 11-20%: 5% and >20%: 7%. 270/498 (54%) were PD-L1-. 43 (8.6%) of tumors had PD-L1 staining in TC (all but 1 were also IC+). PD-L1 IC expression was associated with larger tumor size (p = 0.005), higher nodal stage (≥pN1: 43% vs. 31%, p < 0.001), higher grade (grade 3: 95% vs. 86%, p< 0.001), higher Ki-67 PI (>15%: 88% vs. 69%, p <0.001), and stromal TILs (median score: 40% vs. 10%; p < 0.001). PD-L1 IC status was not associated with patient age. Among histologic subtypes, PD-L1+ tumors were more frequently medullary type (31% vs. 6%) and less frequently metaplastic type (4% vs 10%). At time of this analysis, median follow-up for IDFS and OS were 11 years and 7.2 years, respectively. By univariable analysis, absence of PD-L1 IC expression was associated with poorer IDFS (median: 15.5 vs. 20 years, p = 0.04) and OS (9.5 vs. 17.5 years, p < 0.05).By multivariable analysis, tumor size, stromal TILs, nodal status, and adjuvant chemotherapy (CTX) were significantly associated with IDFS. Age, stromal TILs, nodal status, and receipt of adjuvant CTX were associated with OS. PD-L1+ tumors trended toward improved IDFS (statistical significance not reached), HR: 0.68 (95% CI: 0.45-1.03, p= 0.068) but not OS: 0.90 (95% CI: 0.52-1.57, p= 0.32). Conclusion: Using the PD-L1 SP142 companion assay, almost half of early-stage TNBC were PD-L1+ (IC). However, PD-L1 expression correlated with increasing tumor size and nodal burden, as well as histologic grade, Ki-67 PI, stromal TILs and lymphocyte-enriched subtypes. PD-L1 was associated with improved IDFS and OS in univariable analysis but not multivariable analysis. The majority of the PD-L1+ tumors (73%) had IC scores ≤10%, with heterogeneous tumoral staining. Given the low (1%) assay threshold for positivity, these data emphasize the utility of evaluating PD-L1 in whole tumor sections rather than tissue cores. Citation Format: Jodi M Carter, Mei-Yin C Polley, Jason P Sinnwell, Roberto A Leon-Ferre, Fergus J Couch, Krishna R Kalari, Judy C Boughey, Minetta C Liu, Daniel W Visscher, Matthew P Goetz. Frequency, characteristics and prognostic factors of PD-L1+ triple negative breast cancer using the PD-L1 SP142 companion assay [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr PD1-08.

Abstract Background The da Vinci single‐port (SP) robot is a new instrument for transoral robotic surgery (TORS) in oropharyngeal cancers (OPSCCs). We describe one‐year SP surgical outcomes and compare them to da Vinci Si outcomes. Methods Retrospective cohort study at a high‐volume TORS center. Consecutive patients undergoing TORS SP procedures from 10/2018 to 09/2019 were included. SP OPSCC outcomes were compared to a historical cohort of Si OPSCC patients. t tests were used to compare continuous variables; χ 2 or Wilcoxon rank‐sum tests were used to compare nonparametric categorical variables. Results Seventy‐eight patients underwent SP TORS. The bleed rate was 5.1%, mortality rate was 2.6%, and conversion rate was 0%. Compared to the Si cohort, OPSCC patients undergoing TORS SP procedures saw no significant differences in operative time or post‐TORS bleeds ( P > .05). Conclusions The SP is a comparably safe surgical instrument. Overall learning curve for the SP was rapid among experienced TORS surgeons.

Abstract Background Carcinoembryonic antigen (CEA) levels are used in conjunction with imaging to monitor response to systemic therapy in metastatic colorectal cancer (mCRC). We sought to identify a threshold for CEA change from baseline to predict progressive disease (PD) in mCRC patients receiving first-line therapy. Methods Patients from trials collected in the ARCAD database were included if baseline CEA was at least 10 ng/mL and repeat CEA was available within 14 days of first restaging scan. Optimal cutoffs for CEA change were identified by receiver operating characteristic analysis. Prediction performance of cutoffs was evaluated by sensitivity, specificity, and negative predictive value. Analyses were conducted by treatment class: chemotherapy alone, chemotherapy with anti-VEGF antibody, and chemotherapy with anti-EGFR antibody. Results A total of 2643 mCRC patients treated with systemic therapy were included. Median percent change of CEA from baseline to first restaging for patients with complete response, partial response, or stable disease (non-PD) and PD was −53.1% and +23.6% for chemotherapy alone (n = 957) and −71.7% and −45.3% for chemotherapy with anti-VEGF antibody (n = 1355). The optimal area under the curve cutoff for differentiating PD from non-PD on first restaging was −7.5% for chemotherapy alone and −62.0% for chemotherapy with anti-VEGF antibody; chemotherapy alone, adjusted odds ratio = 6.51 (95% CI = 3.31 to 12.83, P < .001), chemotherapy with anti-VEGF antibody, adjusted odds ratio = 3.45 (95% CI = 1.93 to 6.18, P < .001). A 99% negative predictive value clinical cutoff for prediction of non-PD would avoid CT scan at first restaging in 21.0% of chemotherapy alone and 16.2% of chemotherapy with anti-VEGF antibody–treated patients. Among patients with stable disease on first restaging, those with decreased CEA from baseline had statistically significantly improved progression-free and overall survival. Conclusions Change in CEA from baseline to first restaging can accurately predict non-progression and correlates with long-term outcomes in patients receiving systemic chemotherapy.

TPS7574 Background: Pts with LBCL who have persistent disease assessed by dynamic PET after rituximab-based induction therapy have an increased risk of death (Casasnovas, et al. Blood. 2017). Axi-cel is an autologous anti-CD19 chimeric antigen receptor (CAR) T cell therapy approved for the treatment of pts with relapsed/refractory LBCL with ≥ 2 prior systemic therapies. In ZUMA-1, the registrational study of axi-cel in pts with refractory LBCL, the objective response rate (ORR) was 91% (70% complete response [CR] rate) in pts with double-expressor or high-grade LBCL with ongoing responses in 48% after a median follow-up of 27.1 mos (Locke FL, et al. Lancet Oncol 2019). Furthermore, pts with fewer prior lines of therapy and lower tumor burden had higher rates of ongoing responses and manageable safety (Locke et al. ASCO 2018. 3039). ZUMA-12 will investigate the efficacy and safety of axi-cel as a first-line therapy in newly diagnosed pts with high-risk LBCL who have PET-positive disease after 2 cycles of induction therapy. Methods: This Phase 2 study has a planned enrollment of ≈40 pts aged ≥ 18 y with high-risk LBCL, defined by the presence of MYC and BCL2 and/or BCL6 translocations by FISH or an IPI score ≥ 3 any time before enrollment, and an ECOG performance status of 0 – 1. Before enrollment, pts must have a Deauville score of 4 – 5 (Barrington SF et al. J Clin Oncol. 2014) after 2 cycles of chemoimmunotherapy that includes an anti-CD20 monoclonal antibody and anthracycline. After leukapheresis, pts with bulky or rapidly progressing disease may receive optional non-chemotherapy bridging therapy. Following conditioning therapy with cyclophosphamide (500 mg/m2) and fludarabine (30 mg/m2) for 3 days, pts will receive a single infusion of axi-cel at a target dose of 2 × 106 CAR T cells/kg. The primary endpoint is investigator-assessed CR rate per the Lugano classification (Cheson et al. J Clin Oncol. 2014). Key secondary endpoints include ORR, duration of response, event-free survival, progression-free survival, overall response, safety, relapse with CNS disease and levels of blood CAR T cells and serum cytokines over time. Accrual is ongoing. Clinical trial information: NCT03761056.

7609 Background: Multiple lines of evidence indicate that the Insulin Like Growth Factor 1 Receptor (IGF-1R) plays a key role in the progression of multiple myeloma (MM). IGF-1 is a growth factor for MM cells. It promotes survival to the cytotoxic effects of chemotherapy in animal models of MM and its blood levels has been shown to correlate with those of paraprotein in MM patients. CP-751,871, a fully human monoclonal antibody, is a highly specific and potent inhibitor of the autophosphorylation of IGF-1R. Methods: Based on its mechanism of action and the potential relevance of IGF-1R in MM, a Phase 1 First-in-Human dose escalation study was initiated with the objective to define the safety and tolerability, and to characterize the pharmacokinetic and pharmacodynamic properties of CP-751,871 in this patient population. Patient’s eligibility included previously treated multiple myeloma in relapse or refractory phase and/or less than complete remission following autologous stem cell transplant or tandem transplant. Results: Following informed consent and screening, 10 dose-escalation cohorts of patients received from 0.025 to 10 mg/kg of CP-751,871 by iv infusion on Day 1 of 4-week cycles. In patients with a suboptimal response to CP-751,871 alone, oral dexamethasone was added to the treatment regimen. Patients received up to 14 cycles of CP-751,871 therapy, alone or in combination with dexamethasone. No dose limiting toxicities have been identified to date. Plasma CP-751,871 exposure increases with dose, and the pharmacokinetic characteristics are consistent with target-mediated disposition. Pharmacodynamic measurements indicate complete target saturation by CP-751,871 for the complete length of the dosing period. One near CR and 2 PR in combination with dexamethasone have been reported. Conclusions: These data indicate that CP-751,871 is well tolerated and may constitute a therapeutic approach for patients with multiple myeloma. [Table: see text]

3587 Background: The Insulin like Growth Factor I receptor (IGF-IR), a tyrosine kinase, is widely expressed in human tissues. IGF- IR and its ligands (IGF-I and IGF-II) are expressed by many human cancers (e.g., breast, prostate, colorectal and non-small cell lung). Binding of the ligands to the IGF-IR activates key cellular signaling pathways important for stimulating cellular proliferation and inhibiting apoptosis. IGF- I and IGF-II are present in the circulation, but also locally expressed in neoplastic tissue. Bioavailability of these ligands is regulated by a family of IGF binding proteins (IGFBPs1–6). CP-751,871, a fully human monoclonal antibody, is a highly specific and potent inhibitor of IGF-IR activation. In vitro experiments show that binding of CP 751,871 to IGF-IR induces receptor internalization and degradation. This antibody has been shown to have antineoplastic activity using both in vivo and in vitro pre-clinical models. Methods: Blood samples were collected for characterization of the pharmacokinetic and pharmacodynamic properties of CP-751,871 in phase 1 trials of this agent given to cancer patients either alone or in combination with chemotherapy. The endpoints assessed included among others: CP-751,871 plasma concentrations, total and free IGF-I, IGFBP-3, soluble IGF-IR and IGF-IR expression on granulocytes and tumor cells. Results: CP 751,871 exposure increased with dose over the 800-fold dose range investigated. Pharmacokinetic profiles were consistent with target-mediated disposition. A dose-dependent downregulation of soluble IGF-IR serum concentration and IGF-IR expression was observed, with sustained inhibition for the entire dosing period (3–4 week cycles) observed at doses ≥ 1.5 mg/kg. As predicted for an agent that interferes with IGF-I action, IGF-I and IGFBP-3 serum levels were up-regulated in a similar dose-dependent manner. Conclusions: The pharmacodynamic endpoints of clinical trials provide evidence that CP-751,871 targets IGF-IR in granulocytes, tumor cells and tissues involved in regulation of the growth hormone -IGF-I axis. These data provide proof of principle for the use of CP-751,871 as a first-in-class therapeutic approach to inhibit the IGF-IR pathway in cancer patients. No significant financial relationships to disclose.

Abstract Pathogenic fibrotic diseases, including idiopathic pulmonary fibrosis (IPF), have some of the worst prognoses and affect millions of people worldwide. With unclear etiology and minimally effective therapies, two‐thirds of IPF patients die within 2‐5 years from this progressive interstitial lung disease. Transforming Growth Factor Beta (TGFβ) and insulin‐like growth factor‐1 (IGF‐1) are known to promote fibrosis; however, myofibroblast specific upregulation of IGF‐1 in the initiation and progression of TGFβ‐induced fibrogenesis and IPF have remained unexplored. To address this, the current study (1) documents the upregulation of IGF‐1 via TGFβ in myofibroblasts and fibrotic lung tissue, as well as its correlation with decreased pulmonary function in advanced IPF; (2) identifies IGF‐1's C1 promoter as mediating the increase in IGF‐1 transcription by TGFβ in pulmonary fibroblasts; (3) determines that SMAD2 and mTOR signaling are required for TGFβ‐dependent Igf‐1 expression in myofibroblasts; (4) demonstrates IGF‐1R activation is essential to support TGFβ‐driven profibrotic myofibroblast functions and excessive wound healing; and (5) establishes the effectiveness of slowing the progression of murine lung fibrosis with the IGF‐1R inhibitor OSI‐906. These findings expand our knowledge of IGF‐1's role as a novel fibrotic‐switch, bringing us one step closer to understanding the complex biological mechanisms responsible for fibrotic diseases and developing effective therapies.