Chuang, Tuan L.

Despite advancements in the early-stage detection and expansion of treatments for prostate cancer (PCa), patient mortality rates remain high in patients with aggressive disease and the overtreatment of indolent disease remains a major issue. Prostate-specific antigen (PSA), a standard PCa blood biomarker, is limited in its ability to differentiate disease subtypes resulting in the overtreatment of non-aggressive indolent disease. Here we assess engorged cancer-associated macrophage-like cells (CAMLs), a ≥50 µm, cancer-specific, polynucleated circulating cell type found in the blood of patients with PCa as a potential companion biomarker to PSA for patient risk stratification. We found that rising PSA is positively correlated with increasing CAML size (r = 0.307, p = 0.004) and number of CAMLs in circulation (r = 0.399, p < 0.001). Over a 2-year period, the presence of a single engorged CAML was associated with 20.9 times increased likelihood of progression (p = 0.016) in non-metastatic PCa, and 2.4 times likelihood of progression (p = 0.031) with 5.4 times likelihood of death (p < 0.001) in metastatic PCa. These preliminary data suggest that CAML cell monitoring, in combination with PSA, may aid in differentiating non-aggressive from aggressive PCas by adding biological information that complements traditional clinical biomarkers, thereby helping guide treatment strategies.

Abstract Background: Prostate cancers (PC) are intrinsically complex, with few prognostic biomarkers that differentiate aggressive and indolent disease. Cancer associated macrophage like cells (CAMLs) have shown to be significant independent prognostic indicators for poor survival in tumors if engorged to ≥50μm. However, no group has examined CAMLs' in PC. In this prospective pilot study, we analyzed PSA & ≥50μm CAML presence in (n=51) Stage I-III & (n=41) metastatic PC (mPC) prior to the start of new treatments to examine CAMLs' on outcomes. We found that ≥50μm CAML presence significantly predicted worse patient survival in mPC. These preliminary results suggest that CAMLs may serve as a cheap, non-invasive prognostic biomarker that predicts for worse outcomes in both local & mPC prior to new therapies. Methods: We prospectively recruited (n=92) PC patients in this pilot study to examine CAML's prognostic significance in non-metastatic (stages I-III) and mPC. Of (n=92) total patients, 15% (n=14/92) were stage I, 32% (n=29/92) stage II, 9% (n=8/92) stage III, and 45% (n=41/92) Stage IV. Prior to the induction of new therapy or first line therapy for newly diagnosed patients, 7.5mL peripheral baseline (BL) blood was collected. Blood was filtered via CellSieveTM microfiltration, which excludes cells by size ≥7μm. In parallel, changes in PSA was monitored to compare prognostic significance against ≥50μm CAMLs. Wilcoxon univariate analysis was used to analyze ≥50μm CAMLs and PSA in progression free survival (PFS) and overall survival (OS). Results: CAML's were identified in 78.9% (n=71/90) of available BL samples, with two samples failing from clotting. Stage I-III patients had an average of ~3 CAMLs/7.5mL blood, whereas mPCs contained ~6 CAMLs/7.5mL. Average CAML size increased linearly with advancing stage of disease with stage I patients averaging 23μm, stage II 33μm, stage III 65μm, and stage IV 78μm. Of available BL samples, 41% (n=38/90) patients with ≥50μm CAMLs significantly predicted for worse PFS (HR=10.0, p&lt;0.001, 95%CI=0.07-0.31) and OS (HR=34.2, p&lt;0.001, 95%CI=0.03-0.21). Further, ≥50μm CAMLs significantly predicted for poorer survival in mPC with PFS (HR=9.4, p=0.028, 95%CI=0.18-0.84) and OS (HR=5.1, p=0.003, 95%CI=0.07-0.53), but only non-significantly trended in non-metastatic disease. Initial analysis of PSA found that high PSA at BL was a significant predictor for worse outcomes in patients, while changes in PSA was not a predictor. Conclusions: CAMLs have shown potential as a predictive non-invasive blood based biomarker across multiple solid malignancies, and here we compared this biomarker in PC. While preliminary, these data suggests that engorged CAML presence prior to the start of new treatment may be a statistically significant predictor of survival in both the local and metastatic setting, and a larger validation cohort should be established. Citation Format: Daniel J. Gironda, Raymond Bergan, R K. Alpaugh, Daniel C. Danila, Tuan L. Chuang, Brenda Y. Hurtado, Thai Ho, Cha-Mei Tang, Daniel L. Adams. Cancer associated macrophage like cells predict aggressive disease in local and metastatic prostate cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 357.

3039 Background: Patients with multiple organ metastases have poorer prognoses than those with a single organ metastasis, are frequently associated with drug resistance, and have higher tumor burden. Engorged (≥50um) Cancer Associated Macrophage-Like Cells (CAMLs) are a circulating stromal cell subtype detected in the blood of patients with solid tumors at high risk for recurrence or progression. While numerous studies have shown that ≥50um CAMLs predict poor clinical outcomes, meta-analysis of these studies have also suggested that hyper engorged CAMLs ≥100um (heCAMLs) may be associated with multifocal metastatic disease and even worse outcomes. In this prospective study, we evaluated the presence of heCAMLs in patients with metastatic disease and demonstrated a strong relationship with multi organ spread, which also correlated with shorter Progression Free Survival (PFS) and Overall Survival (OS). Methods: We prospectively recruited 151 patients with metastatic (m) mbreast (n = 58), mlung (n = 34), mprostate (n = 39), and mrenal (n = 20) cancers. Peripheral blood was collected prior to the induction of new treatment for metastatic cancer. Cells were isolated following standard CellSieve techniques, then imaged and measured in ZenBlue. Multi organ metastasis was defined as spread to ≥2 distant organ sites, or any spread to the brain. Single factor ANOVA was conducted to compare heCAML presence in multi organ metastatic patients versus patients with single organ site metastasis. Univariate and multivariate analysis was run to evaluate for PFS and OS against heCAMLs, and all known clinical parameters. Results: 150 viable samples (excluding 1 failed sample) were obtained. Multi organ metastases were present in 55% (n = 83/150) of patients. heCAMLs were found in 59% (n = 49/83) of the multi organ metastatic population, but only in 16% (n = 11/67) of the single site metastatic cohort (p < 0.001). heCAML presence appeared to differentiate multi organ vs single organ metastases in mbreast (85% vs. 52%, p = 0.006), mlung (71% vs. 26%, p = 0.025), mprostate (75% vs. 37%, p = 0.029), and mRCC (88% vs. 36%, p = 0.025). Further, in all n = 150 patients, heCAML presence predicted a significantly shorter median PFS of 4.5 versus 7.2 months, 24 month PFS (HR = 1.67, 95%CI = 1.13-2.45, p = 0.013), and significantly shorter median OS of 13.1 versus 20.4 months, 24 month OS (HR = 2.05, 95%CI = 1.24-3.39, p = 0.008). Conclusions: We examined a non-invasive prognostic blood based assay to determine its relationship to multi organ metastatic spread as well as its prognostic value in several solid cancers. These results showed patients with heCAMLs had higher rates of multi organ metastases, and appear to predict for shorter PFS and OS. Studies of larger cohorts are needed for prospective validation of these initial findings.