BackgroundRIBBON-1, a Phase III, multicenter, randomized, placebo-controlled trial in patients with previously untreated MBC was designed to evaluate the efficacy and safety of adding bevacizumab (B) to chemotherapy regimens including capecitabine (Cape; n=615); a taxane (T; n=307), or an anthracycline (Anth; n=315) compared with chemotherapy alone. Pre-specified analyses of progression-free survival PFS) in the Cape and pooled T/Anth cohorts, the primary endpoints of the study were increased upon addition of B. In the Cape cohort, median PFS increased from 5.7 to 8.6 mo (HR=0.69, p-value=0.0002) and in the T/Anth cohort, it increased from 8.0 to 9.2 mo (HR=0.64; p-value<0.0001).MethodsRECIST was used to determine objective response rate (ORR). Patients without a post-baseline tumor assessment were considered non-responders. The primary analysis for the ORR and the duration of response was performed using only patients with measurable disease at baseline. ORR was formally compared between the two treatment arms using the Mantel-Haenszel Chi-squared test, using the randomization stratification factors. Fisher's exact test was also performed. Clinical benefit rate (CBR) was defined as the proportion of patients with a complete or partial response or with stable disease at Week 24. Exploratory analyses of CBR and time to response are provided here. Summary statistics of time to response at Week 9 will be presented as will the final analysis of the secondary endpoint of overall survival.ResultsAnalyses of ORR and CBR are provided in the following table. CapeTaxaneAnth PL (n=206)B (n=409)PL (n=104)B (n=203)PL (n=103)B (n=212)Patients with measurable disease, n (%)161 (78.2)325 (61.1)85 (81.7)161 (79.3)92 (89.3)184 (86.8)ORR, %23.635.435.350.340.252.2CR, n (%)1 (0.6)7 (2.2)3 (3.5)4 (2.5)2 (2.2)3 (1.6)PR, n (%)37 (23.0)108 (33.2)27 (31.8)77 (47.8)35 (38.0)93 (50.5)Difference between arms, %11.815.012.0p-value, unstratified0.00940.030.073Duration of ORMedian, mo7.29.28.68.46.08.1HR (95% CI)0.61 (0.39–0.96)0.75 (0.45–1.27)0.53 (0.34–0.83)Log-rank p-value0.03260.2840.0047Clinical benefit rate*, %47.164.365.471.969.980.7p-value, unstratified<0.00010.240.04CR+PR at Week 9, %20.229.438.354.544.451.1B=bevacizumab, cape=capecitabine, CI=confidence interval, HR=hazard ratio, OR=objective response, PL=placebo, T/Anth=taxane/anthracycline.*For randomized patients.ConclusionsIn patients with HER2-negative MBC, the addition of bevacizumab to capecitabine, taxane or anthracycline chemotherapy induces more responses and those responses occur more rapidly. For capecitabine and anthracycline the addition of bevacizumab leads to objective responses that last longer. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6084.

The heterogeneous tumor microenvironment (TME) is highly complex and not entirely understood. These complex configurations lead to the generation of oxygen-deprived conditions within the tumor niche, which modulate several intrinsic TME elements to promote immunosuppressive outcomes. Decoding these communications is necessary for designing effective therapeutic strategies that can effectively reduce tumor-associated chemotherapy resistance by employing the inherent potential of the immune system. While classic two-dimensional in vitro research models reveal critical hypoxia-driven biochemical cues, threedimensional (3D) cell culture models more accurately replicate the TME-immune manifestations. In this study, we review various 3D cell culture models currently being utilized to foster an oxygen-deprived TME, those that assess the dynamics associated with TME-immune cell penetrability within the tumor-like spatial structure, and discuss state of the art 3D systems that attempt recreating hypoxia-driven TME-immune outcomes. We also highlight the importance of integrating various hallmarks, which collectively might influence the functionality of these 3D models. This review strives to supplement perspectives to the quickly-evolving discipline that endeavors to mimic tumor hypoxia and tumor-immune interactions using 3D in vitro models.

BackgroundThree multicenter, randomized, placebo-controlled Phase III trials of taxane (T), or capecitabine (Cape), or anthracycline (Anth) chemotherapy plus or minus bevacizumab (B) established that the addition of B improves progression-free survival (PFS). Outcomes in clinically important subsets are important to demonstrate the consistency of treatment effect and may guide physicians when considering treatment options for patients. Here we compare various clinically relevant subgroups across three studies to assess the activity of B in patients for these subgroups.MethodsResults for PFS based upon investigator assessments were used from all trials. Kaplan-Meier methodology was used to estimate median PFS for chemo+placebo and chemo+B for patient subgroups from the E2100, AVADO, and RIBBON-1 studies. For the overall study results, stratified hazard ratios (HRs) are presented with the same stratification factors as the variables that were used for the randomization, while unstratified HRs are presented here for the subgroups.ResultsIn all 3 studies we observed an improvement in PFS upon addition of B to chemotherapy. For patients with triple-negative (ER-, PR-, HER2-) tumors, the addition of B led to an increase in median PFS (mPFS) from 4.7 mo to 10.2 mo (HR=0.45; 95% confidence interval [CI], 0.33-0.61) in E2100, from 6.0 to 8.1 mo in the AVADO 15 mg/kg B arm (HR=0.60, 95% CI, 0.39-0.92); from 4.2 to 6.1 mo in the RIBBON-1 Cape cohort (HR=0.72, 95% CI, 0.49-1.06); and from 8.2 to 14.5 mo in the RIBBON-1 T/Anth cohort (HR=0.78, 95% CI, 0.53-1.15).For patients ≥65 yr, the addition of B led to an increase in mPFS from 7.4 to 10.4 mo (HR=0.69, 95% CI, 0.46-1.03) in E2100, from 7.6 to 8.4 mo in the AVADO 15 mg/kg B arm (HR=0.62, 95% CI, 0.36-1.08); from 6.2 to 9.1 mo in the RIBBON-1 Cape cohort (HR=0.69, 95% CI, 0.47-1.02); and from 8.5 to 10.1 mo in the RIBBON-1 T/Anth cohort (HR=0.83, 95% CI, 0.52-1.34).For patients who had received prior adjuvant T, the addition of B led to an increase in mPFS from 4.4 to 13.3. mo in E2100 (HR=0.29; 95% CI, 0.19-0.46), 6.6 to 8.5 mo in the AVADO 15 mg/kg B arm (HR=0.42; 95% CI, 0.23-0.77), 4.2 to 8.7 mo in the RIBBON-1 Cape cohort (HR=0.62; 95% CI, 0.45-0.84); and from 6.7 to 9.1 mo in the RIBBON-1 T/Anth cohort (HR=0.65; 95% CI, 0.39-1.09).ConclusionsAlthough the addition of bevacizumab consistently improved mPFS across a number of clinically relevant subsets, regardless of the chemotherapy backbone used, absolute improvements in HRs and median PFS varied within subsets and across the three trials. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 207.

Central nervous system atypical teratoid/rhabdoid tumors (ATRTs) are rare and aggressive tumors with a very poor prognosis. Current treatments for ATRT include resection of the tumor, followed by systemic chemotherapy and radiation therapy, which have toxic side effects for young children. Gene expression analyses of human ATRTs and normal brain samples indicate that ATRTs have aberrant expression of epigenetic markers including class I histone deacetylases (HDAC’s) and lysine demethylase (LSD1). Here, we investigate the effect of a small molecule epigenetic modulator known as Domatinostat (4SC-202), which inhibits both class I HDAC’s and Lysine Demethylase (LSD1), on ATRT cell survival and single cell heterogeneity. Our findings suggest that 4SC-202 is both cytotoxic and cytostatic to ATRT in 2D and 3D scaffold cell culture models and may target cancer stem cells. Single-cell RNA sequencing data from ATRT-06 spheroids treated with 4SC-202 have a reduced population of cells overexpressing stem cell-related genes, including SOX2. Flow cytometry and immunofluorescence on 3D ATRT-06 scaffold models support these results suggesting that 4SC-202 reduces expression of cancer stem cell markers SOX2, CD133, and FOXM1. Drug-induced changes to the systems biology landscape are also explored by multi-omics enrichment analyses. In summary, our data indicate that 4SC-202 has both cytotoxic and cytostatic effects on ATRT, targets specific cell sub-populations, including those with cancer stem-like features, and is an important potential cancer therapeutic to be investigated in vivo.

Oxygen deprivation within tumors is one of the most prevalent causes of resilient cancer cell survival and increased immune evasion in breast cancer (BCa). Current in vitro models do not adequately mimic physiological oxygen levels relevant to breast tissue and its tumor-immune interactions. In this study, we propose an approach to engineer a three-dimensional (3D) model (named 3D engineered oxygen, 3D-O) that supports the growth of BCa cells and generates physio-and pathophysiological oxygen levels to understand the role of oxygen availability in tumor-immune interactions. BCa cells (MDA-MB-231 and MCF-7) were embedded into plasma-derived 3D-O scaffolds that reflected physio-and pathophysiological oxygen levels relevant to the healthy and cancerous breast tissue. BCa cells grown within 3D-O scaffolds were analyzed by flow cytometry, confocal imaging, immunohistochemistry/immunofluorescence for cell proliferation, extracellular matrix protein expression, and alterations in immune evasive outcomes. Exosome secretion from 3D-O scaffolds were evaluated using the NanoSight particle analyzer. Peripheral blood mononuclear cells were incorporated on the top of 3D-O scaffolds and the difference in tumor-infiltrating capabilities as a result of different oxygen content were assessed by flow cytometry and confocal imaging. Lastly, hypoxia and Programmed death-ligand 1 (PD-L1) inhibition were validated as targets to sensitize BCa cells in order to overcome immune evasion. Low oxygen-induced adaptations within 3D-O scaffolds validated known tumor hypoxia characteristics such as reduced BCa cell proliferation, increased extracellular matrix protein expression, increased extracellular vesicle secretion and enhanced immune surface marker expression on BCa cells. We further demonstrated that low oxygen in 3D-O scaffolds significantly influence immune infiltration. CD8+ T cell infiltration was impaired under pathophysiological oxygen levels and we were also able to establish that hypoxia and PD-L1 inhibition re-sensitized BCa cells to cytotoxic CD8+ T cells. Bioengineering the oxygen-deprived BCa tumor microenvironment in our engineered 3D-O physiological and tumorous