Citations

Abstract Background: Tumor surface PD-L1 (B7-H1) signals through T-cell surface receptor PD-1 to suppress antitumor immunity. PD-1 inhibitors like pembrolizumab block this pathway to prevent tumor escape from immunosurveillance. These PD-1 checkpoint inhibitors achieve objective response in 20-30% of patients with melanoma (1-3). As the majority of these patients are resistant to this treatment, there is a critical need to combat PD-1 checkpoint inhibitor resistance in melanoma. What is the mechanism of PD-1 checkpoint inhibitor resistance in melanoma? Our group has reported that soluble PD-L1 (sPD-L1, sB7-H1) is elevated in the serum of patients with PD-1 inhibitor-resistant melanoma and non-small cell lung cancer (NSCLC) (4). We have also shown that soluble PD-L1 is produced by cleavage from other tumor types and leads to apoptosis in CD8+ T-cells (5). The aim of this study is to confirm the source of sPD-L1 in human melanoma and its relation to outcomes. Methods: B7H1-expressing transgenic melanoma cells (Mel-B7H1) were treated with an array of protease inhibitors over 24 hours. Cells were then pelleted and supernatants were analyzed by ELISA for sPD-L1 (sB7-H1) production. Tumor serum samples were also analyzed by ELISA for sPD-L1 production.Tumor pathology slides from patients with melanoma (serum donors from the above study) were stained by immunohistochemistry with antibodies against proteases ADAM10 or ADAM17. Slides were visualized by microscopy for the presence of these antigens. Activated human CD8+ T-cells were cultured with recombinant human B7-H1 (PD-L1) protein, sPD-L1-rich, or sPD-L1-depleted supernatants from a tumor cell line in the presence of placebo or PD-1 checkpoint inhibitor antibodies. Cell survival was measured at 48 hours by flow cytometry.Results: ADAM10 inhibitor GI254023X, ADAM17 inhibitor TAPI-0, and broad metalloprotease inhibitor TAPI-2 inhibited Mel-B7H1 production of sB7H1 (p<0.001, 0.095, and 0.001 respectively). Specific inhibitors of other metalloproteases did not significantly alter sB7H1 production. PD-L1 transcription levels were not significantly altered. Tumor pathology slides from patients with high serum sPD-L1 exhibited high ADAM10 and/or ADAM17 staining. Conversely, tumors from patients with low-sPD-L1levels tended to exhibit low ADAM10 and/or ADAM17 staining. Recombinant PD-L1 and PD-L1-rich supernatants induced cell death of CD8+ T-cells, whereas PBS control solution and PD-L1-depleted supernatants did not. Supraphysiologic doses of pembrolizumab decreased cell death in PD-L1-rich supernatant-treated CD8+ T-cells. Conclusions: Matrix metalloprotease inhibitors ADAM10 and ADAM17 mediate sPD-L1 production from melanoma cells. In samples from patients with melanoma, immunohistochemical staining of these proteases in tumor tissue correlates with serum sPD-L1 levels. As we have shown previously, sPD-L1 induces apoptosis of activated CD8+ T-cells, which may explain PD-1 inhibitor resistance in most patients with melanoma.We posit that sPD-L1 outcompetes PD-1 inhibitors to suppress tumor immunosurveillance. Our results suggest that the combination of ADAM10/17 inhibitor and PD-1 checkpoint inhibitor may overcome this mechanism of PD-1 resistance in melanoma and other cancers. Future studies will determine (A) how a combined ADAM10/17 inhibitor and PD-1 inhibitor may function in clinical use, (B) how tumor-derived sPD-L1 signals downstream to cause apoptosis in T-cells, and (C) whether surface ADAM10/17 predict surface PD-L1 staining in melanoma. References: 1. Ribas et al., Lancet Oncol 2015;16(8):908–18. 2. Hamid et al., Ann Oncol 2016;27:6. 3. Weber et al., Lancet Oncol 2015:16(4):375–84. 4. Dronca et al., J Clin Oncol 2017:35(15):11534. 5. Orme et al., AACR Adv Malig Lymphoma 2018. Citation Format: Jacob J. Orme, Khalid Jazieh, Susan Harrington, Matthew Ball, Tariq U. Azam, Xin (Cindy) Liu, Tiancheng Xie, Aaron Mansfield, Roxana S. Dronca, Haidong Dong. Tumor-associated ADAM10 and ADAM17 produce soluble PD-L1 (sPD-L1, sB7-H1) and affect downstream tumor immunity – A resistance mechanism to PD-1 checkpoint blockade in melanoma [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A210.

Abstract Objectives We sought to identify clinical, electrocardiographic (ECG), and angiographic characteristics that are predictive of 3‐year mortality after primary percutaneous coronary intervention (PCI) in patients with non‐anterior ST‐elevation myocardial infarction (NA‐STEMI) from the Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction (HORIZONS‐AMI) trial. Background Which patients with NA‐STEMI undergoing PCI have a poor prognosis is uncertain. Methods NA‐STEMI was defined as ST‐segment elevation in lateral (V5, V6, I, aVL), inferior (II, III, aVF), or inferolateral (I, II, III, aVF, and V5‐V6) ECG leads or posterior myocardial infarction with ST‐segment depression of ≥1 mm in ≥2 contiguous anterior leads. Cox regression was used to identify independent predictors of 3‐year mortality. Missing data were imputed using multiple imputation. Results In HORIZONS‐AMI, 2,578/3,602 patients had no prior coronary artery bypass grafting, underwent single‐vessel PCI, and had baseline ECG data assessed in an independent core laboratory. Among them, 1,495 (58.0%) had NA‐STEMI. Patients with NA‐STEMI had lower 3‐year mortality risk than those with anterior STEMI (4.5% versus 7.1%, P = 0.004). The independent predictors of increased 3‐year mortality in NA‐STEMI were older age (median > 59.0 years), diabetes, reduced LVEF (≤50%), Killip class ≥2, post‐procedure TIMI flow 0–2 versus 3, renal insufficiency, and ST‐resolution <30% at 60 min post‐PCI. Patients with 0, 1, 2, 3, and ≥4 of these risk factors had 3‐year mortality rates of 1.8%, 2.3%, 3.1%, 6.1%, and 36.3%, respectively ( P < 0.0001). Conclusions Although NA‐STEMI carries a better prognosis than anterior STEMI, high‐risk patient cohorts with NA‐STEMI may be identified who have substantial 3‐year mortality.

The prevalence of Lynch syndrome (LS) varies significantly in different populations, suggesting that ethnic features might play an important role. We enrolled 3330 consecutive Chinese patients who had surgical resection for newly diagnosed colorectal cancer. Universal screening for LS was implemented, including immunohistochemistry for mismatch repair (MMR) proteins, BRAFV600E mutation test and germline sequencing. Among the 3250 eligible patients, MMR protein deficiency (dMMR) was detected in 330 (10.2%) patients. Ninety‐three patients (2.9%) were diagnosed with LS. Nine (9.7%) patients with LS fulfilled Amsterdam criteria II and 76 (81.7%) met the revised Bethesda guidelines. Only 15 (9.7%) patients with absence of MLH1 on IHC had BRAFV600E mutation. One third (33/99) of the MMR gene mutations have not been reported previously. The age of onset indicates risk of LS in patients with dMMR tumors. For patients older than 65 years, only 2 patients (5.7%) fulfilling revised Bethesda guidelines were diagnosed with LS. Selective sequencing of all cases with dMMR diagnosed at or below age 65 years and only of those dMMR cases older than 65 years who fulfill revised Bethesda guidelines results in 8.2% fewer cases requiring germline testing without missing any LS diagnoses. While the prevalence of LS in Chinese patients is similar to that of Western populations, the spectrum of constitutional mutations and frequency of BRAFV600E mutation is different. Patients older than 65 years who do not meet the revised Bethesda guidelines have a low risk of LS, suggesting germline sequencing might not be necessary in this population.

Patients with severe, treatment-refractory asthma are at risk for death from acute exacerbations. The cytokine IL17A has been associated with airway inflammation in severe asthma, and novel therapeutic targets within this pathway are urgently needed. We recently showed that IL17A increases airway contractility by activating the procontractile GTPase RhoA. Here, we explore the therapeutic potential of targeting the RhoA pathway activated by IL17A by inhibiting RhoA guanine nucleotide exchange factors (RhoGEFs), intracellular activators of RhoA. We first used a ribosomal pulldown approach to profile mouse airway smooth muscle by qPCR and identified Arhgef12 as highly expressed among a panel of RhoGEFs. ARHGEF12 was also the most highly expressed RhoGEF in patients with asthma, as found by RNA sequencing. Tracheal rings from Arhgef12-KO mice and WT rings treated with a RhoGEF inhibitor had evidence of decreased contractility and RhoA activation in response to IL17A treatment. In a house dust mite model of allergic sensitization, Arhgef12-KO mice had decreased airway hyperresponsiveness without effects on airway inflammation. Taken together, our results show that Arhgef12 is necessary for IL17A-induced airway contractility and identify a therapeutic target for severe asthma.

To improve the outcome of relapsed/refractory acute myeloid leukemia (AML), a randomized phase II trial of three novel regimens was conducted. Ninety patients were enrolled and were in first relapse or were refractory to induction/re‐induction chemotherapy. They were randomized to the following regimens: carboplatin‐topotecan (CT), each by continuous infusion for 5 days; alvocidib (formerly flavopiridol), cytarabine, and mitoxantrone (FLAM) in a timed sequential regimen; or sirolimus combined with mitoxantrone, etoposide, and cytarabine (S‐MEC). The primary objective was attainment of a complete remission (CR). A Simon two‐stage design was used for each of the three arms. The median age of the patients in the FLAM arm was older at 62 years compared with 55 years for the CT arm and the S‐MEC arm. The overall response was 14% in the CT arm (5/35, 90% CI 7%‐35%), 28% in the FLAM arm (10/36, 90% CI, 16%‐43%), and 16% in the S‐MEC arm (3/19, 90% CI, 4%‐36%). There were nine treatment‐related deaths, seven of which occurred in the FLAM arm with four of these in elderly patients. We conclude that the FLAM regimen had an encouraging response rate and should be considered for further clinical development but should be used with caution in elderly patients.

Intrahepatic cholangiocarcinoma (iCCA) has over the last 10‐20 years become the focus of increasing concern, largely due to its rising incidence and high mortality rates worldwide. The significant increase in mortality rates from this primary hepatobiliary cancer, particularly over the past decade, has coincided with a rapidly growing interest among clinicians, investigators, and patient advocates to seek greater mechanistic insights and more effective biomarker‐driven targeted approaches for managing and/or preventing this challenging liver cancer. In addition to discussing challenges posed by this aggressive cancer, this review will emphasize recent epidemiological, basic, and translational research findings for iCCA. In particular, we will highlight emerging demographic changes and evolving risk factors, the critical role of the tumor microenvironment, extracellular vesicle biomarkers and therapeutics, intertumoral and intratumoral heterogeneity, and current and emerging targeted therapies regarding iCCA. Specifically, recent evidence linking non–bile duct medical conditions, such as nonalcoholic fatty liver disease and nonspecific cirrhosis, to intrahepatic cholangiocarcinogenesis together with geographic and ethnic variation will be assessed. Recent developments concerning the roles played by transforming growth factor‐β and platelet‐derived growth factor D in driving the recruitment and expansion of cancer‐associated myofibroblasts within cholangiocarcinoma (CCA) stroma as well as their therapeutic implications will also be discussed. In addition, the potential significance of extracellular vesicles as bile and serum biomarkers and therapeutic delivery systems for iCCA will be described. An integrated systems approach to classifying heterogeneous iCCA subtypes will be further highlighted, and recent clinical trials and emerging targeted therapies will be reviewed, along with recommendations for future translational research opportunities. Established international CCA networks are now facilitating collaborations aimed at advancing iCCA translational and clinical research.

11534 Background: To date, there are no validated blood-based biomarkers of predicting response to PD-1 blockade. We previously reported that Bim is a downstream signaling molecule of the PD-1 pathway, and that measurement of Bim levels in circulating T-cells may predict and monitor responses to anti–PD-1 therapy in melanoma. We have identified the existence of sPD-L1 in cancer patients and showed that the sPD-L1 is biologically active and capable of triggering apoptosis in activated T-cells. Here we evaluated T cell Bim and sPD-L1 in the peripheral blood (PB) as biomarkers of response in a cohort of patients with metastatic melanoma and lung cancer undergoing anti-PD1 therapy. Methods: 60 pts treated with anti-PD-1 had PB collected at baseline and at radiographic tumor evaluation. Frequencies of Bim+ T cells and Bim median fluorescence intensity (MFI) were measured by flow cytometry in gated tumor-reactive CD11ahighPD1+ CD8+ T cells. We also measured levels of sPD-L1 at baseline and serially during treatment with sPD-L1 ELISA. Baseline Bim and sPD-L1 levels and percent change in Bim levels in patients (pts) who had a radiographic response (CR/PR) were compared to those who had progressive disease (PD) at 12 wks. Results: Similarly to previously reported preliminary data, pts with objective response (CR/PR, 15/60) after 4 cycles of anti-PD1 therapy had higher frequency of Bim T cells at baseline compared to pts with PD (16/60) (mean 43% vs. 30%, P = 0.0484). The frequencies of Bim+ T cells decreased significantly after the first 3 months of treatment in responders compared with progressors (mean -16% vs. + 40% P = 0.0111). High baseline sPD-L1 were associated with progression on anti-PD1 therapy (mean 2.8 ng/mL vs. 0.7 ng/mL, p = 0.07, n = 13) and the levels increased by the first tumor assessment in patients resistant to anti-PD-1. Conclusions: Measurements of Bim and sPD-L1 levels may help to select patients who are likely to benefit from anti-PD1 monotherapy versus combinatorial strategies, and provide a new non-invasive way to monitor response to anti-PD-1 blockade. A larger validation study is underway.

Abstract Introduction Circulating tumor cells (CTCs) have been shown to be prognostic in patients (pts) with metastatic breast cancer (MBC) (Pukazhendhi, Gluck, J Carcinog. 2014). The tnAcity trial evaluated the efficacy/safety of 3 chemotherapy combination regimens (nab-P/carboplatin [C], nab-P/gemcitabine [G], or G/C) as first-line treatment for pts with mTNBC. nab-P/C resulted in a significantly longer PFS & numerically higher ORR vs nab-P/G or G/C (Yardley. SABCS 2016; manuscript in process). CTC levels were assessed at baseline (BL) & during treatment to determine correlation with clinical benefit. Methods Pts with pathologically confirmed mTNBC & no prior cytotoxic chemotherapy for MBC received (1:1:1) nab-P 125 mg/m2 with C area under the curve (AUC) 2, nab-P 125 mg/m2 with G 1000 mg/m2, or G 1000 mg/m2 with C AUC 2, all given d1 & 8 q3w. Primary endpoint: investigator-assessed PFS. Secondary endpoints included ORR & OS; CTC enumeration was a prespecified exploratory objective. CTC levels, assessed (CELLSEARCH®) at BL & start of cycles 3 & 5 (post-BL), were grouped as follows: 0 CTCs/7.5 mL blood at BL (−−), ≥ 1 CTCs/7.5 mL blood at BL & post-BL (++), & ≥ 1 CTCs/7.5 mL blood at BL & clearance of CTCs in ≥ 1 post-BL measurement (+−). Results In total, 126 pts were included: 48, 24, & 54 in the −−, ++, & +− groups, respectively. Mean BL CTC levels for the ++ & +− groups were 55 & 66 CTCs/7.5 mL blood. Pts with BL CTCs of ≥ 1 vs 0 had numerically similar median PFS (7.0 vs 5.9 mo; HR 1.45 [95% CI 0.93 - 2.25]) & OS (15.0 vs 16.0 mo; HR 0.90 [95% CI 0.57 - 1.42]) & higher ORR (64% vs 44%). Mean cycle 3 & 5 CTC levels in the ++ group were 17 & 111 CTCs/7.5 mL blood. Pts in the −− & +− groups had longer PFS vs the ++ group (median 5.9, 8.5, & 4.7 months). Similar improvements in OS & ORR were noted (Table). Conclusions Absence of CTCs at BL & during treatment & clearance of CTCs from BL at least once during treatment were generally associated with improved efficacy outcomes in pts with mTNBC treated with combination chemotherapy. Table. Outcomes by Change in CTC Level from BaselineGroupOutcome−− n = 48+− n = 54++ n = 24PFS, median, mo HR (95% CI)5.9 0.60 (0.34-1.06)a8.5 0.30 (0.17-0.54)a4.7OS, median, mo HR (95% CI)16.0 0.40 (0.22-0.73)a17.8 0.35 (0.20-0.62)a9.8ORR, %43.879.629.2CR6.316.74.2PR37.563.025.0SD35.420.454.2PD16.7—16.7NE4.2——CR, complete response; HR, hazard ratio; NE, not evaluable; ORR, overall response rate; OS, overall survival; PD, progressive disease; PFS, progression-free survival; PR, partial response; SD, stable disease. a vs ++ group. Citation Format: Minetta C. Liu, Wolfgang Janni, Vassilis Georgoulias, Denise A. Yardley, Nadia Harbeck, Xin Wei, Desmond McGovern, Robert Beck. First-line doublet chemotherapy for mTNBC: circulating tumor cell analysis of the tnAcity trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4209.