Citations

Background Data about anticoagulation in pulmonary arterial hypertension (PAH) patients are inconsistent. The objective of this study was to examine the impact of adjunctive oral anticoagulants in patients with PAH through meta-analysis, and to further assess whether response differs by PAH subtype. Methods and Results Cochrane CENTRAL, Medline, and Scopus databases were searched for randomized or nonrandomized studies that assessed the association between anticoagulation and outcomes in patients with PAH. Hazard ratios (HRs) for mortality were pooled using the random effects model. Subgroup analyses were performed for type of PAH and study design. Twelve nonrandomized studies, at moderate risk of bias, were included. These consisted of 2512 patients (1342 receiving anticoagulation and 1170 controls). Anticoagulation significantly reduced mortality in the overall PAH cohort (HR, 0.73 [0.57, 0.93]; P =0.001; I 2 =64%). On subgroup analysis, a significant mortality reduction was seen in idiopathic PAH patients (HR, 0.73 [0.56, 0.95]; P =0.02; I 2 =46%), whereas no significant difference was observed in connective tissue disease–related PAH (HR, 1.16 [0.58, 2.32]; P =0.67; I 2 =71%). Sensitivity analysis specific to scleroderma-associated PAH demonstrated a significant increase in mortality with anticoagulant use (HR, 1.58 [1.08, 2.31]; P =0.02; I 2 =9%). Conclusions This meta-analysis shows that use of anticoagulation may improve survival in idiopathic PAH patients, while increasing mortality when used in scleroderma-associated-PAH patients. Currently, no randomized clinical trials have been published, and until randomized data are available, anticoagulant use in PAH should be tailored to PAH subtype.

11503 Background: Cancer Associated Macrophage-Like cells (CAMLs) are a recently described circulating stromal cell subtype commonly found in the peripheral blood of patients in all stages of solid malignancies and in a variety of cancer subtypes. However, while their biological association to cancer is being studied, their clinical utilization as it relates to cancer prognosis has not been evaluated. Methods: A two year prospective study was undertaken to evaluate the relationship of CAMLs and overall survival (OS) in 6 solid tumor types. The single blind multi-institutional study consisted of 269 stage I-IV patients; breast (n = 57), esophageal (n = 21), prostate (n = 43), pancreatic (n = 59), lung (n = 54), and renal cell (n = 35), in treatment (n = 134) and untreated baseline (n = 135). 7.5mL of whole blood was filtered by CellSieve microfiltration assay and CAMLs enumerated, as previously described. Patients were grouped by CAML number ( < 6 or ≥6) and by size ( < 49 or ≥50 µm) to evaluate hazard ratios (HR) by censored univariate & multivariate analysis. Results: CAMLs were identified in 93% of samples, averaging 8.2 CAMLs/7.5mL blood sample, and found in all 6 cancers at baseline and during treatment. Average CAML number was associated with disease stage and CAML positivity was 4.4 & 80% (Stage I), 4.7 & 93% (Stage II), 9.3 & 98% (Stage 3), 12.1 & 97% (Stage IV). Univariate analysis of patients (n = 269) stratified by ≥6 CAMLs had reduced OS (HR = 1.8, 95%CI 1.1-2.9, p = 0.03). Further, CAML size also had reduced OS in patients with ≥50 µm CAMLs (HR = 2.7, 95%CI 1.8-4.0, p < 0.0001). Conclusions: Our data suggests that in solid malignancies, CAML number and size appear to clinically correlate with OS in early and late stage disease. Given these results relating CAMLs with OS, further analysis is warranted to determine if CAMLs can serve as a clinically-relevant blood-based marker.

4003 Background: Pembro has shown promising antitumor activity and manageable safety in a phase 1 study of pts with previously treated advanced gastric cancer. We conducted a global, multicohort, phase 2 study of pembro in pts with advanced gastric or gastroesophageal junction (G/GEJ) cancer (KEYNOTE-059;NCT02335411). Methods: Cohort 1 enrolled 259 pts, aged ≥18 y with measurable recurrent or metastatic G/GEJ adenocarcinoma who had progressed on ≥2 prior chemotherapy regimens and had ECOG PS 0-1. Pts received pembro 200 mg Q3W up to 2 y or up to disease progression, investigator/pt decision to withdrawal, or unacceptable toxicity. PD-L1+pts had expression in ≥1% tumor or stromal cells using IHC (22C3 antibody). Primary end points: ORR (RECIST 1.1, by central review), safety, and tolerability. Results: Of 259 pts in cohort 1, 76.4% were men; median age was 62.0 y. 51.7% and 48.3% received pembro as 3rd-line (3L) and 4L+ therapy, respectively. 57.1% had PD-L1+ tumors. At data cutoff (Oct 19, 2016), median duration of follow-up was 5.4 mo (range, 0.5 to 18.7). Overall ORR (CR + PR) was 11.2% (95% CI, 7.6-15.7); 1.9% of pts (95% CI, 0.6-4.4) had CR, 9.3% had PR (95% CI, 6.0-13.5), 17% (95% CI, 12.6-22.1) had SD, and 55.6% (95% CI, 49.3-61.7) had PD. Median DOR was 8.1 mo (range, 1.4+ to 15.1+). ORR was 14.9% (95% CI, 9.4-22.1) in 3L pts and 7.2% (95% CI, 3.3-13.2) in 4L+. In PD-L1+ pts, ORR was 15.5% (95% CI, 10.1-22.4) with 2.0% (95% CI, 0.4-5.8) CR and 13.5% (95% CI, 8.5-20.1) PR; in PD-L1– pts, ORR was 5.5% (95% CI, 2.0-11.6), with 1.8% (95% CI, 0.2-6.5) CR and 3.7% (95% CI, 1.0-9.1) PR. In 3L pts with PD-L1+ tumors, ORR was 21.3% (95% CI, 12.7-32.3), with 4.0% (95% CI, 0.8-11.2) CR; in 3L pts with PD-L1– tumors, ORR was 6.9% (95% CI, 1.9-16.7), with 3.4% (95% CI, 0.4-11.9) CR. Grade 3-5 treatment-related AEs (TRAEs) occurred in 43 pts (16.6%). TRAEs led to discontinuation in 2 pts (abnormal LFT, bile duct stenosis) and were fatal in 2 pts (acute kidney injury, pleural effusion). Conclusions: Pembro showed encouraging efficacy and manageable safety after ≥2 prior lines of therapy in pts with advanced G/GEJ cancer in this large phase 2 trial. Survival and additional biomarker data, including MSI status, will be presented. Clinical trial information: NCT02335411.

Abstract Castleman disease (CD) describes a group of heterogeneous hematologic disorders with characteristic histopathological features. CD can present with unicentric or multicentric (MCD) regions of lymph node enlargement. Some cases of MCD are caused by human herpesvirus-8 (HHV-8), whereas others are HHV-8–negative/idiopathic (iMCD). Treatment of iMCD is challenging, and outcomes can be poor because no uniform treatment guidelines exist, few systematic studies have been conducted, and no agreed upon response criteria have been described. The purpose of this paper is to establish consensus, evidence-based treatment guidelines based on the severity of iMCD to improve outcomes. An international Working Group of 42 experts from 10 countries was convened by the Castleman Disease Collaborative Network to establish consensus guidelines for the management of iMCD based on published literature, review of treatment effectiveness for 344 cases, and expert opinion. The anti–interleukin-6 monoclonal antibody siltuximab (or tocilizumab, if siltuximab is not available) with or without corticosteroids is the preferred first-line therapy for iMCD. In the most severe cases, adjuvant combination chemotherapy is recommended. Additional agents are recommended, tailored by disease severity, as second- and third-line therapies for treatment failures. Response criteria were formulated to facilitate the evaluation of treatment failure or success. These guidelines should help treating physicians to stratify patients based on disease severity in order to select the best available therapeutic option. An international registry for patients with CD (ACCELERATE, #NCT02817997) was established in October 2016 to collect patient outcomes to increase the evidence base for selection of therapies in the future.

Abstract Background: Blood-based biomarkers (PSA, CEA, CA125) are used to track real-time progression of disease in parallel with imaging. However, while numerous blood biomarkers exist, they are specific to cancer type (i.e., PSA to prostate and CEA to colon) and may not appear in all diseased individuals. Recently, cancer-associated macrophage-like cells (CAMLs), a circulating stromal cell subtype, were identified in various solid cancer types, which were observed increasing in size and in hyperploidy during progressive disease. To assess whether CAML enlargement is a biomarker of progression/response, we tracked CAML growth/shrinkage in a pilot study of patients (n=34). Blood was drawn from patients with lung, prostate, or breast cancers over a 3-month period, baseline through 2 treatment cycles, followed by continued monitoring for 2 years. These data suggest that morphologic assessment of CAMLs (growth/hyperploidy) appear to parallel cancer progression, or response to treatment, in multiple solid tumors. Methods: A prospective multi-institutional study used anonymized peripheral blood samples from 34 cancer patients undergoing therapy [stage I (n=2), II (n=3), III (n=8) & IV (n=21)] with breast (n=10), lung (n=16), & prostate (n=8). Samples were taken prior to therapy (BL), at 1 month (FU1) follow-up and a 3-month (FU2) follow-up, after induction of therapy. Blood was processed by the CellSieve™ microfiltration technique at 4 institutions and stained for cytokeratin 8, 18 and 19, CD14 and CD45. After identification and quantification, CAMLs were measured based on their hyperploidy and cell size. Results: CAMLs were found in 97% of cancer patients at BL, 97% at FU1 and 91% of FU2. Over the 2-year follow-up, 7 patients showed no signs of clinical disease progression, while 27 patients had observable progression. Of the 7 patients who did not progress, only two had CAMLs of ≥50µm at BL and at FU1, but whose CAMLs shrunk to &lt;50 µm by FU2. Of the 27 patients who progressed, 22 patients had ≥50µm CAMLs at all time points, while 5 patients had small &lt;50µm CAMLs at BL. Interestingly, CAMLs in these 5 patients had enlarged to ≥50µm by the FU2 time point. Conclusions: We show that increased polynucleation and CAML enlargement indicate shorter progression-free survival in a number of cancer types after baseline. By monitoring CAML changes over time for the 34 individual patients, we demonstrated correlation of ongoing progression, or response, in tumors to the enlargement or shrinkage in CAMLs at follow-up time points from treatment induction. This pilot study suggests that CAMLs have the potential to monitor the progression/regression of malignancy in real time and suggests the need for larger validation studies. Citation Format: Daniel L. Adams, Raymond Bergan, Martin J. Edelman, Stuart S. Martin, Rena Lapidus, Saranya Chumsri, Cha-Mei Tang, Steven H. Lin. Real-time monitoring of solid tumor progression by circulating stromal cells from early- to late-stage disease [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 1560.