Ho, Thai H.

9517 Background: Although PD-1/L1 axis directed therapies induce durable responses in some mm patients (pts), biomarkers of response remain elusive. We hypothesized that quantifying key immune suppression mechanisms within the tumor microenvironment would provide superior predictors of response to anti-PD-1 compared with single marker assessment. Methods: Pre-treatment tumor biopsies from 124 mm pts treated with anti-PD-1 at 7 academic centers were fluorescently stained with multiple immune markers in discovery (n = 24) and validation (n = 100) cohorts. Selected biomarker signatures, PD-1/PD-L1 interaction score (proportion of PD-1+ cells co-localized with PD-L1) and IDO1/HLA-DR co-expression were evaluated for anti-PD-1 treatment response and survival. Slides were imaged using Vectra; biomarker positive cells and their co-localization were objectively quantified in pathologist-selected regions using novel Automated Quantitative Analysis (AQUA) algorithms. Results: In the discovery cohort, high levels of PD-1/PD-L1 interaction score and/or IDO1/HLA-DR coexpression was strongly positively associated with response to anti-PD-1 (p = 0.0005). In contrast, other individual biomarkers (PD-1, PD-L1, CD8) were not associated with response or survival (p > 0.10). This finding was replicated in the validation cohort: pts with high PD-1/PD-L1 and/or IDO1/HLA-DR were more likely to respond to treatment (p = 0.009). These pts also experienced a three-fold increase in progression free survival (hazards ratio (HR) = 0.33; p = 0.003) and overall survival (HR = 0.34; p = 0.004). Multivariate analyses revealed that these findings were independent of BRAF mutation, stage, LDH and prior therapy. In the combined cohort (n = 124), 80% of responding pts had higher levels of PD-1/PD-L1 interaction scores and/or IDO1/HLA-DR. In contrast, PD-L1 expression alone (≥1% or ≥50%) was not predictive of PFS or OS (p > 0.1). Conclusions: This novel multiplexed method profiling key tumor-immune suppression pathways identified mm pts likely to respond to anti-PD-1 therapy. This method could help stratify patients for PD-1 monotherapy and be useful in guiding future clinical trials.

Abstract Background: We previously demonstrated that cancer associated macrophage-like cells (CAMLs) are cancer specific giant polyploid cells circulating in the blood of patients with solid tumors. Building on our initial discovery, others have shown that these hyperploidy cells are an innate immune response that is associated with decreased survival. However to date, no studies have been done to elucidate their clinical significance as in relation to the various stages of malignant disease. We established a 4 year prospective study of 315 patients from a variety of solid tumors (breast, prostate, lung, renal cell, pancreas, and esophageal) comparing the morphological properties of CAMLs in both early and late stage disease as they relate to progression free and overall survival (PFS/OS). These data suggest that CAML size appears have a strong negative correlation with progression and survival of cancer patients, irregardless of stage of disease, indicating their possible use as a non-invasive blood based biomarker in solid tumors. Methods: A prospective multi-institutional study used anonymized peripheral blood from 315 cancer patients [stage I (n=62), stage II (n=72), stage III (n=69) & stage IV (n=106)] from subjects with breast (n=59), esophageal (n=27), lung (n=59), renal cell carcinoma (n=37), prostate (n=74), pancreas cancers (n=59). CAMLs were isolated by the CellSieve™ microfiltration technique at 5 institutions and stained for cytokeratin 8, 18, & 19, CD14 and CD45. After imaging, a size based threshold ≥50µm was used to separate the patient cohorts, based on previously published assessments. Results: At least one CAML was found in 92% of cancer patients (n=289/315), with the lowest sensitivity in stage 1 (86%), followed by stage 2 (90%), stage 3 (97%) and stage 4 (95%). The property of CAML size was then evaluated. Overall, CAMLs of <50µm in size had superior PFS (HR: 3.8; 95% CI 2.8-5.3; p<0.001) and OS (HR=3.8; 95% CI 2.6-5.7;p<0.001) than those with ≥50 µm CAMLs. By each stage individually, stage 1 (PFS HR=7.5; 95% CI 3.2-17.7; p<0.001), stage II (PFS; HR=4.1; 95% CI 1.9-8.8; p<0.001), stage III (PFS HR=3.1; 95% CI 1.7-5.7; p=0.007), and stage IV (PFS HR=2.7; 95% CI 1.6-4.4; p<0.001). Conclusions: In this first large scale prospective study of the clinical utility of CAMLs, it appears that they are present in every stages of invasive solid tumor malignancies, with prevalence increasing with stage. Interestingly decreased CAML size was found to be associated with improved outcome and longer PFS. These data suggest that CAML detection and size assessment constitute a new real time predictor of progression, and survival in both early and late stage disease indicating the need for additional validation studies. Citation Format: Daniel L. Adams, Steven H. Lin, R. Katherine Alpaugh, Thai Ho, Jeffrey R. Marks, Stuart S. Martin, Susan Tsai, Saranya Chumsri, Cha-Mei Tang, Massimo Cristofanilli, Raymond Bergan. Cancer associated macrophage-like (CAMLs) cells in blood predict progression and survival for all stages of solid tumors [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 2631.

Abstract Background: X4P-001 is an orally bioavailable, selective, allosteric inhibitor of the chemokine receptor CXCR4, and has been shown to downregulate hypoxia inducible factor-2α (HIF-2α) and myeloid-derived suppressor cell (MDSC) trafficking in the tumor microenvironment. In multiple RCC xenograft models, the addition of X4P-001 to tyrosine kinase inhibitors (TKIs), including axitinib, has demonstrated increased efficacy and delayed onset of TKI resistance. Methods: This is an ongoing phase 1/2 open-label study of X4P-001 in combination with axitinib in patients (pts) with histologically confirmed clear cell RCC (ccRCC) who have received ≥1 prior systemic therapy. The Ph1 portion of the study evaluates safety, tolerability, PK, PD, and antitumor activity of the combination using a 3+3 dose escalation schema (escalating doses of X4P-001+ axitinib at 5 mg BID). The Ph2 portion is a single-arm expansion cohort evaluating this combination treatment in ~ 45 ccRCC pts. The radiologic assessment is performed every 8 weeks with central review. Results: As of 30 June, 2017, enrollment for the Ph1 portion of the study has been completed. Sixteen (16) pts were enrolled and the median age was 64 years (range 50-76). Pts had received a median of 2 prior lines of therapy (range 1-5). The doses tested were 200 mg BID, 400 and 600 mg QD of X4P-001 + axitinib. There were two dose-limiting toxicities (DLTs) observed at the X4P-001 600 mg QD dose level: one pt had multiple grade (G) 2 adverse events (AEs), including anorexia, cognitive disturbance, fatigue, nausea, vomiting, and somnolence; another pt had G3 dyspnea and fatigue. The MTD/RP2D was determined to be 400 mg QD of X4P-001 + axitinib. Treatment-related AEs (≥ 10%) of any grade were diarrhea, fatigue, hypertension, nausea, headache, anorexia, vomiting, dry eye, dysphonia, abnormal loss of weight, increased lipase, proteinuria, dry mouth, stomatitis, cognitive disorder, dysgeusia, and palmar-plantar erythrodysaesthesia syndrome. Treatment-related G3/4 AEs (≥ 10%) were hypertension. In addition, one pt had SAE due to G2 diarrhea and G2 creatinine elevation. Drug exposures (AUC0-24hr) at steady state (SS) are similar for 200 mg BID and 400 mg QD dose. Mean Cmax and AUC0-24hr at SS increased approximately 1.6- and 1.9-fold, respectively, from 400 mg to 600 mg QD dose. Leukocyte mobilization is a well-established surrogate marker for CXCR4 inhibition. At both 400 mg and 600 mg daily dose levels, X4P-001 demonstrated approximately 2 to 2.5-fold increase of WBC (range: 1.4-4.7 fold) and nearly 4-fold increase of CD34+ progenitor cells (range: 1.8-6.4 fold). The peak elevation of both markers occurred around 2 to 4 hours following dosing. Of the 12 clinically evaluable pts, 3 had confirmed partial response, 8 had stable disease, and 1 had progressive disease. As of 30 June 2017, 9 pts remain on study and median duration on treatment was 27 weeks (range 7.4-60). Conclusions: The combination treatment is well tolerated at a dose of 400 mg QD of X4P-001 + axitinib with preliminary evidence of clinical activity. The doses used in this phase I study were biologically active in inhibiting CXCR4 in peripheral blood as demonstrated by elevating WBC and CD34+ cell counts. The Ph2 portion of the study is ongoing. Citation Format: Michael Atkins, Richard Joseph, Thai Ho, Ulka Vaishampayan, Sarah Ali, Marc Matrana, Robert Alter, Jeff Edenfield, Yan Wang, Sarah Blanchette, Lu Gan, David McDermott. A phase 1 dose-finding study of X4P-001 (an oral CXCR4 inhibitor) and axitinib in patients with advanced renal cell carcinoma (RCC) [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B201.

Abstract Purpose: PD-1/L1 axis–directed therapies produce clinical responses in a subset of patients; therefore, biomarkers of response are needed. We hypothesized that quantifying key immunosuppression mechanisms within the tumor microenvironment by multiparameter algorithms would identify strong predictors of anti–PD-1 response. Experimental Design: Pretreatment tumor biopsies from 166 patients treated with anti–PD-1 across 10 academic cancer centers were fluorescently stained with multiple markers in discovery (n = 24) and validation (n = 142) cohorts. Biomarker-positive cells and their colocalization were spatially profiled in pathologist-selected tumor regions using novel Automated Quantitative Analysis algorithms. Selected biomarker signatures, PD-1/PD-L1 interaction score, and IDO-1/HLA-DR coexpression were evaluated for anti–PD-1 treatment outcomes. Results: In the discovery cohort, PD-1/PD-L1 interaction score and/or IDO-1/HLA-DR coexpression was strongly associated with anti–PD-1 response (P = 0.0005). In contrast, individual biomarkers (PD-1, PD-L1, IDO-1, HLA-DR) were not associated with response or survival. This finding was replicated in an independent validation cohort: patients with high PD-1/PD-L1 and/or IDO-1/HLA-DR were more likely to respond (P = 0.0096). These patients also experienced significantly improved progression-free survival (HR = 0.36; P = 0.0004) and overall survival (HR = 0.39; P = 0.0011). In the combined cohort, 80% of patients exhibiting higher levels of PD-1/PD-L1 interaction scores and IDO-1/HLA-DR responded to PD-1 blockers (P = 0.000004). In contrast, PD-L1 expression was not predictive of survival. Conclusions: Quantitative spatial profiling of key tumor-immune suppression pathways by novel digital pathology algorithms could help more reliably select melanoma patients for PD-1 monotherapy. Clin Cancer Res; 24(21); 5250–60. ©2018 AACR.

Pazopanib is an approved treatment for renal cell carcinoma and a second-line treatment for nonadipocytic soft-tissue sarcoma. However, its clinical efficacy is limited by its cardiovascular side effects. Pazopanib and other vascular endothelial growth factor receptor tyrosine kinase inhibitors have been associated with the development of hypertension, QT interval prolongation, and other cardiovascular events; however, these mechanisms are largely unknown. Gaining a deeper understanding of these mechanisms is essential for the development of appropriate surveillance strategies and possible diagnostic biomarkers to allow us to monitor patients and modulate therapy prior to significant cardiac insult. This approach will be vital in keeping patients on these life-saving therapies and may be applicable to other tyrosine kinase inhibitors as well. In this review, we provide a comprehensive overview of the preclinical and clinical side effects of pazopanib with a focus on the mechanisms responsible for its toxicity to the cardiovascular system.