Citations

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.

7034 Background: In a phase II study in 50 elderly patients (pts) with AML who were not eligible for intensive chemotherapy, treatment with pracinostat + azacitidine (AZA) was well tolerated, led to 42% complete remission (CR) rate and a median overall survival (OS) of 19.1 months (Blood 2016: 128;100). Here we investigate the impact of somatic mutations and their clearance on disease response and patient outcomes. Methods: 88 samples from 41 study pts were sequenced. All 41 pts were analyzed pre-treatment, and a median of 3 longitudinal samples were analyzed from 19 pts between Cycle 2 and 9. Mutations were assayed by SureSelect targeted capture exon sequencing (Agilent) of 295 genes that are recurrently mutated in hematologic malignancies. Longitudinal mutation clearance was analyzed by plotting variant allele frequency (VAF). Results: At baseline, 96 mutations in 28 genes were detected in 38 pts, with the most frequent being in SRSF2 (27%), DNMT3A (20%), IDH2 (17%), RUNX1 (17%), and TET2(17%). Mutations associated with CR rate and OS are indicated in the Table. A CR was achieved in 10/19 pts that had longitudinal sequencing analysis and at the time of CR, 9 (90%) had persistently detectable mutations in their bone marrow. In 7 of them, continued exposure to pracinostat + AZA lowered the VAF or cleared residual mutations. In 2 pts, relapsed samples showed re-expansion of the founder clone. Conclusions: Mutations in NPM1, and DNA methylation pathway were associated with a better response to pracinostat + AZA, while TP53 mutation was associated with a poor response. Persistent mutation at the time of CR suggests residual preleukemic clonal hematopoiesis in this elderly population. Benefit of prolonged exposure to pracinostat + AZA was also confirmed at molecular level where continued decline of mutation VAF was seen after achieving CR. Clinical trial information: NCT01912274. [Table: see text]

533 Background: Current guidelines define TNBC as complete absence of estrogen (ER) and progesterone receptor (PR), without HER2 amplification. However, the prognostic impact of clinical and histopathological factors, sTILs, and AdjCT in TNBC meeting these strict criteria is unknown. Methods: From a cohort of 9985 women who underwent upfront surgery for M0 breast cancer (BC) at Mayo Clinic Rochester from 1985-2012, 1159 pts with ER negative or low (≤10%) BC were identified for central ER/PR/HER2 staining and HER2 FISH (IHC2+ only) to select those with TNBC by modern definitions. Cox proportional hazards models were used to assess the impact of clinicopathological variables on invasive disease-free (IDFS) and overall survival (OS). Results: Tumors from 605 pts (median age 56.3 yrs) met criteria for TNBC (ER < 1%, PR < 1% and HER2 0, 1 or 2+ and FISH negative). 51% were T1, 65% N0, 88% grade 3, and 75% had Ki67 > 15%. Histologically, 39% were anaplastic, 26% invasive ductal, 16% medullary, 8% metaplastic, 6% apocrine and 5% others. Median sTILs was 20% (0-90%). 55% pts received AdjCT [21% anthracycline (A), 19% A + taxane, and 15% other]. Median follow-up for IDFS and OS were 7.4 and 10.6 yrs, respectively. Multivariate analyses demonstrated that higher N stage (p < 0.01), lower sTILs (p = 0.01) and no AdjCT (p < 0.01) were independently associated with worse IDFS and OS. Histology (medullary subtype) was associated with better IDFS in univariate (HR 0.56, 95% CI, 0.35-0.89) but not in multivariate analyses, once sTILs were accounted for. Among systemically untreated pts (n = 182), higher N (p < 0.01) and lower sTILs (p = 0.04) were associated with worse IDFS. For systemically untreated T1N0 pts (n = 111), the 5-yr IDFS was 70% (95% CI, 61-81) [T1a: 83% (95% CI, 63-100), T1b: 68% (95% CI, 52-88) and T1c: 67% (95% CI, 55-83)], compared to 78% (95% CI, 68-84) for T1N0 pts treated with AdjCT. Conclusions: In TNBC pts, N stage, sTILs and receipt of AdjCT were independently prognostic for IDFS and OS. sTILs remained prognostic for IDFS in systemically untreated TNBC. In N0 TNBC, the risk of recurrence or death was substantial in the absence of chemotherapy, even for those with T1 tumors.

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.