Magnetic resonance imaging of tumor response to stroma-modifying pegvorhyaluronidase alpha (PEGPH20) therapy in early-phase clinical trials.

Pre-clinical and clinical studies have shown that PEGPH20 depletes intratumoral hyaluronic acid (HA), which is linked to high interstitial fluid pressures and poor distribution of chemotherapies. 29 patients with metastatic advanced solid tumors received quantitative magnetic resonance imaging (qMRI) in 3 prospective clinical trials of PEGPH20: HALO-109-101 (NCT00834704), HALO-109-102 (NCT01170897), and HALO-109-201 (NCT01453153). Apparent Diffusion Coefficient of water (ADC), T1, ktrans, vp, ve, and iAUC maps were computed from qMRI acquired at baseline and ≥ 1 time point post-PEGPH20. Tumor ADC and T1 decreased, while iAUC, ktrans, vp, and ve increased, on day 1 post-PEGPH20 relative to baseline values. This is consistent with HA depletion leading to a decrease in tumor extracellular water content and an increase in perfusion, permeability, extracellular matrix space, and vascularity. Baseline parameter values predictive of pharmacodynamic responses were: ADC > 1.46 × 10-3 mm2/s (Balanced Accuracy (BA) = 72%, p < 0.01), T1 > 0.54 s (BA = 82%, p < 0.01), iAUC < 9.2 mM-s (BA = 76%, p < 0.05), ktrans < 0.07 min-1 (BA = 72%, p = 0.2), ve < 0.17 (BA = 68%, p < 0.01), and vp < 0.02 (BA = 60%, p < 0.01). A low ve at baseline was moderately predictive of response in any parameter (BA = 65.6%, p < 0.01 averaged across patients). These qMRI biomarkers are potentially useful for guiding patient pre-selection and post-treatment follow-up in future clinical studies of PEGPH20 and other tumor stroma-modifying anti-cancer therapies.

Tumor Response to Stroma-Modifying Therapy: Magnetic Resonance Imaging Findings in Early-Phase Clinical Trials of Pegvorhyaluronidase alpha (PEGPH20).

Pre-clinical and clinical studies have shown that PEGPH20 depletes intratumoral hyaluronic acid (HA), which is linked to high interstitial fluid pressures and poor distribution of chemotherapies. 29 patients with metastatic advanced solid tumors received quantitative magnetic resonance imaging (qMRI) in 3 prospective clinical trials of PEGPH20, HALO-109-101 (NCT00834704), HALO-109-102 (NCT01170897), and HALO-109-201 (NCT01453153). Apparent Diffusion Coefficient of water (ADC), T1, ktrans, vp, ve, and iAUC maps were computed from qMRI acquired at baseline and ≥ 1 time point post-PEGPH20. Tumor ADC and T1 decreased, while iAUC, ktrans, vp, and ve increased, on day 1 post-PEGPH20 relative to baseline values. This is consistent with HA depletion leading to a decrease in tumor water content and an increase in perfusion, permeability, extracellular matrix space, and vascularity. Baseline parameter values that were predictive of pharmacodynamic responses were: ADC > 1.46×10-3 mm2/s (Balanced Accuracy (BA) = 72%, p < 0.01), T1 > 0.54s (BA = 82%, p < 0.01), iAUC < 9.2 mM-s (BA = 76%, p < 0.05), ktrans<0.07min-1 (BA = 72%, p = 0.2), ve<0.17 (BA = 68%, p < 0.01), and vp<0.02 (BA = 60%, p < 0.01). Further, ve<0.39 at baseline was moderately predictive of response in any parameter (BA = 65.6%, p < 0.01 averaged across patients). These qMRI biomarkers are potentially useful for guiding patient pre-selection and post-treatment follow-up in future clinical studies of PEGPH20 and other tumor stroma-modifying anti-cancer therapies.

Sirtuin 6 is required for the integrated stress response and resistance to inhibition of transcriptional cyclin-dependent kinases.

Pancreatic ductal adenocarcinoma (PDAC) is classified into two key subtypes, classical and basal, with basal PDAC predicting worse survival. Using in vitro drug assays, genetic manipulation experiments, and in vivo drug studies in human patient-derived xenografts (PDXs) of PDAC, we found that basal PDACs were uniquely sensitive to transcriptional inhibition by targeting cyclin-dependent kinase 7 (CDK7) and CDK9, and this sensitivity was recapitulated in the basal subtype of breast cancer. We showed in cell lines, PDXs, and publicly available patient datasets that basal PDAC was characterized by inactivation of the integrated stress response (ISR), which leads to a higher rate of global mRNA translation. Moreover, we identified the histone deacetylase sirtuin 6 (SIRT6) as a critical regulator of a constitutively active ISR. Using expression analysis, polysome sequencing, immunofluorescence, and cycloheximide chase experiments, we found that SIRT6 regulated protein stability by binding activating transcription factor 4 (ATF4) in nuclear speckles and protecting it from proteasomal degradation. In human PDAC cell lines and organoids as well as in murine PDAC genetically engineered mouse models where SIRT6 was deleted or down-regulated, we demonstrated that SIRT6 loss both defined the basal PDAC subtype and led to reduced ATF4 protein stability and a nonfunctional ISR, causing a marked vulnerability to CDK7 and CDK9 inhibitors. Thus, we have uncovered an important mechanism regulating a stress-induced transcriptional program that may be exploited with targeted therapies in particularly aggressive PDAC.

Epithelial and stromal co-evolution and complicity in pancreatic cancer.

Pancreatic ductal adenocarcinomas are distinguished by their robust desmoplasia, or fibroinflammatory response. Dominated by non-malignant cells, the mutated epithelium must therefore combat, cooperate with or co-opt the surrounding cells and signalling processes in its microenvironment. It is proposed that an invasive pancreatic ductal adenocarcinoma represents the coordinated evolution of malignant and non-malignant cells and mechanisms that subvert and repurpose normal tissue composition, architecture and physiology to foster tumorigenesis. The complex kinetics and stepwise development of pancreatic cancer suggests that it is governed by a discrete set of organizing rules and principles, and repeated attempts to target specific components within the microenvironment reveal self-regulating mechanisms of resistance. The histopathological and genetic progression models of the transforming ductal epithelium must therefore be considered together with a programme of stromal progression to create a comprehensive picture of pancreatic cancer evolution. Understanding the underlying organizational logic of the tumour to anticipate and pre-empt the almost inevitable compensatory mechanisms will be essential to eradicate the disease.

Insufficiency of compound immune checkpoint blockade to overcome engineered T cell exhaustion in pancreatic cancer.

BACKGROUND: Achieving robust responses with adoptive cell therapy for the treatment of the highly lethal pancreatic ductal adenocarcinoma (PDA) has been elusive. We previously showed that T cells engineered to express a mesothelin-specific T cell receptor (TCRMsln) accumulate in autochthonous PDA, mediate therapeutic antitumor activity, but fail to eradicate tumors in part due to acquisition of a dysfunctional exhausted T cell state. METHODS: Here, we investigated the role of immune checkpoints in mediating TCR engineered T cell dysfunction in a genetically engineered PDA mouse model. The fate of engineered T cells that were either deficient in PD-1, or transferred concurrent with antibodies blocking PD-L1 and/or additional immune checkpoints, were tracked to evaluate persistence, functionality, and antitumor activity at day 8 and day 28 post infusion. We performed RNAseq on engineered T cells isolated from tumors and compared differentially expressed genes to prototypical endogenous exhausted T cells. RESULTS: PD-L1 pathway blockade and/or simultaneous blockade of multiple coinhibitory receptors during adoptive cell therapy was insufficient to prevent engineered T cell dysfunction in autochthonous PDA yet resulted in subclinical activity in the lung, without enhancing anti-tumor immunity. Gene expression analysis revealed that ex vivo TCR engineered T cells markedly differed from in vivo primed endogenous effector T cells which can respond to immune checkpoint inhibitors. Early after transfer, intratumoral TCR engineered T cells acquired a similar molecular program to prototypical exhausted T cells that arise during chronic viral infection, but the molecular programs later diverged. Intratumoral engineered T cells exhibited decreased effector and cell cycle genes and were refractory to TCR signaling. CONCLUSIONS: Abrogation of PD-1 signaling is not sufficient to overcome TCR engineered T cell dysfunction in PDA. Our study suggests that contributions by both the differentiation pathways induced during the ex vivo T cell engineering process and intratumoral suppressive mechanisms render engineered T cells dysfunctional and resistant to rescue by blockade of immune checkpoints.

Mesenchymal Lineage Heterogeneity Underlies Nonredundant Functions of Pancreatic Cancer-Associated Fibroblasts.

Cancer-associated fibroblast (CAF) heterogeneity is increasingly appreciated, but the origins and functions of distinct CAF subtypes remain poorly understood. The abundant and transcriptionally diverse CAF population in pancreatic ductal adenocarcinoma (PDAC) is thought to arise from a common cell of origin, pancreatic stellate cells (PSC), with diversification resulting from cytokine and growth factor gradients within the tumor microenvironment. Here we analyzed the differentiation and function of PSCs during tumor progression in vivo. Contrary to expectations, we found that PSCs give rise to a numerically minor subset of PDAC CAFs. Targeted ablation of PSC-derived CAFs within their host tissue revealed nonredundant functions for this defined CAF population in shaping the PDAC microenvironment, including production of specific extracellular matrix components and tissue stiffness regulation. Together, these findings link stromal evolution from distinct cells of origin to transcriptional heterogeneity among PDAC CAFs and demonstrate unique functions for CAFs of a defined cellular origin. SIGNIFICANCE: By tracking and ablating a specific CAF population, we find that a numerically minor CAF subtype from a defined cell of origin plays unique roles in establishing the pancreatic tumor microenvironment. Together with prior studies, this work suggests that mesenchymal lineage heterogeneity and signaling gradients diversify PDAC CAFs.See related commentary by Cukierman, p. 296.This article is highlighted in the In This Issue feature, p. 275.

Cx43 phosphorylation sites regulate pancreatic cancer metastasis.

Pancreatic ductal adenocarcinoma (PDA) is aggressive, highly metastatic and characterized by a robust desmoplasia. Connexin proteins that form gap junctions have been implicated in tumor suppression for over 30 years. Cx43, the most widely expressed connexin, regulates cell behaviors, including migration and proliferation. Thus, we hypothesized that Cx43 could regulate PDA progression. Phosphorylation of Cx43 by Casein Kinase 1 (CK1) regulates gap junction assembly. We interbred the well-established KrasLSL-G12D/+;p48Cre/+ (KC) mouse model of PDA with homozygous "knock-in" mutant Cx43 mice bearing amino acid substitution at CK1 sites (Cx43CK1A) and found profound and surprising effects on cancer progression. Crossing the Cx43CK1A mouse onto the KC background (termed KC;CxCK1A) led to significant extension of lifespan, from a median of 370 to 486 days (p = 0.03) and a decreased incidence of metastasis (p = 0.045). However, when we examined early stages of disease, we found more rapid onset of tissue remodeling in the KC;CxCK1A mouse followed by divergence to a cystic phenotype. During tumorigenesis, gap junctions are increasingly present in stromal cells of the KC mice but are absent from the KC;Cx43CK1A mice. Tail vein metastasis assays with cells derived from KC or KC;CxCK1A tumors showed that KC;CxCK1A cells could efficiently colonize the lung and downregulate Cx43 expression, arguing that inhibition of metastasis was not occurring at the distal site. Instead, stromal gap junctions, their associated signaling events or other unknown Cx43-dependent events facilitate metastatic capacity in the primary tumor.

Cholesterol Biosynthesis Influences Subtype Specificity and Plasticity in Pancreas Cancer.

Cellular plasticity contributes to intratumoral heterogeneity, metastatic spread, and treatment resistance of cancers. In this issue of Cancer Cell, Gabitova-Cornell et al. identify the potential to inadvertently develop an undifferentiated and more aggressive pancreas cancer with agents commonly prescribed to manage heart disease risk.

Randomized Phase III Trial of Pegvorhyaluronidase Alfa With Nab-Paclitaxel Plus Gemcitabine for Patients With Hyaluronan-High Metastatic Pancreatic Adenocarcinoma.

PURPOSE: To evaluate the efficacy and safety of pegvorhyaluronidase alfa (PEGPH20) plus nab-paclitaxel/gemcitabine (AG) in patients with hyaluronan-high metastatic pancreatic ductal adenocarcinoma (PDA). PATIENTS AND METHODS: HALO 109-301 was a phase III, randomized, double-blind, placebo-controlled study. Patients ≥ 18 years of age with untreated, metastatic, hyaluronan-high PDA were randomly assigned 2:1 to PEGPH20 plus AG or placebo plus AG. Treatment was administered intravenously in 4-week cycles (3 weeks on, 1 week off) until progression or intolerable adverse events: PEGPH20 3.0 µg/kg twice per week for cycle 1 and once per week thereafter; nab-paclitaxel 125 mg/m2 once per week; and gemcitabine 1,000 mg/m2 once per week. The primary end point was overall survival (OS); secondary end points included progression-free survival (PFS), objective response rate (ORR), and safety. Response was independently assessed per RECIST v1.1. RESULTS: At data cutoff, 494 patients were randomly assigned, with 492 (327 for PEGPH20 and 165 for placebo) included in intention-to-treat analyses. Baseline characteristics were balanced for PEGPH20 plus AG versus placebo plus AG. There were 330 deaths, with a median OS of 11.2 months for PEGPH20 plus AG versus 11.5 months for placebo plus AG (hazard ratio [HR], 1.00; 95% CI, 0.80 to 1.27; P = .97); median PFS was 7.1 months versus 7.1 months (HR, 0.97 [95% CI, 0.75 to 1.26]); ORR was 47% versus 36% (ORR ratio, 1.29 [95% CI, 1.03 to 1.63]). Grade ≥ 3 adverse events with a ≥ 2% higher rate with PEGPH20 plus AG than with placebo plus AG included fatigue (16.0% v 9.6%), muscle spasms (6.5% v 0.6%), and hyponatremia (8.0% v 3.8%). CONCLUSION: The addition of PEGPH20 to AG increased the ORR but did not improve OS or PFS. The safety profile of PEGPH20 plus AG was consistent with that found in previous studies. These results do not support additional development of PEGPH20 in metastatic PDA.

A framework for advancing our understanding of cancer-associated fibroblasts.

Cancer-associated fibroblasts (CAFs) are a key component of the tumour microenvironment with diverse functions, including matrix deposition and remodelling, extensive reciprocal signalling interactions with cancer cells and crosstalk with infiltrating leukocytes. As such, they are a potential target for optimizing therapeutic strategies against cancer. However, many challenges are present in ongoing attempts to modulate CAFs for therapeutic benefit. These include limitations in our understanding of the origin of CAFs and heterogeneity in CAF function, with it being desirable to retain some antitumorigenic functions. On the basis of a meeting of experts in the field of CAF biology, we summarize in this Consensus Statement our current knowledge and present a framework for advancing our understanding of this critical cell type within the tumour microenvironment.

Non-Invasive Monitoring of Stromal Biophysics with Targeted Depletion of Hyaluronan in Pancreatic Ductal Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDA) is characterized by a pronounced fibroinflammatory stromal reaction consisting of inordinate levels of hyaluronan (HA), collagen, immune cells, and activated fibroblasts that work in concert to generate a robust physical barrier to the perfusion and diffusion of small molecule therapeutics. The targeted depletion of hyaluronan with a PEGylated recombinant human hyaluronidase (PEGPH20) lowers interstitial gel-fluid pressures and re-expands collapsed intratumoral vasculature, improving the delivery of concurrently administered agents. Here we report a non-invasive means of assessing biophysical responses to stromal intervention with quantitative multiparametric magnetic resonance imaging (MRI) at 14 Tesla (T). We found that spin-spin relaxation time T2 values and glycosaminoglycan chemical exchange saturation transfer (GagCEST) values decreased at 24 h, reflecting depletion of intratumoral HA content, and that these parameters recovered at 7 days concurrent with replenishment of intratumoral HA. This was also reflected in an increase in low-b apparent diffusion coefficient (ADC) at 24 h, consistent with improved tumor perfusion that again normalized at 7 days after treatment. Phantom imaging suggests that the GagCEST signal is driven by changes in HA versus other glycosaminoglycans. Thus, multiparametric magnetic resonance imaging (MRI) can be used as a non-invasive tool to assess therapeutic responses to targeted stromal therapy in PDA and likely other stroma-rich solid tumors that have high levels of hyaluronan and collagen.

Differential Effects of Depleting versus Programming Tumor-Associated Macrophages on Engineered T Cells in Pancreatic Ductal Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDA) is a lethal malignancy resistant to therapies, including immune-checkpoint blockade. We investigated two distinct strategies to modulate tumor-associated macrophages (TAM) to enhance cellular therapy targeting mesothelin in an autochthonous PDA mouse model. Administration of an antibody to colony-stimulating factor (anti-Csf1R) depleted Ly6Clow protumorigenic TAMs and significantly enhanced endogenous T-cell intratumoral accumulation. Despite increasing the number of endogenous T cells at the tumor site, as previously reported, TAM depletion had only minimal impact on intratumoral accumulation and persistence of T cells engineered to express a murine mesothelin-specific T-cell receptor (TCR). TAM depletion interfered with the antitumor activity of the infused T cells in PDA, evidenced by reduced tumor cell apoptosis. In contrast, TAM programming with agonistic anti-CD40 increased both Ly6Chigh TAMs and the intratumoral accumulation and longevity of TCR-engineered T cells. Anti-CD40 significantly increased the frequency and number of proliferating and granzyme B+ engineered T cells, and increased tumor cell apoptosis. However, anti-CD40 failed to rescue intratumoral engineered T-cell IFNγ production. Thus, although functional modulation, rather than TAM depletion, enhanced the longevity of engineered T cells and increased tumor cell apoptosis, ultimately, anti-CD40 modulation was insufficient to rescue key effector defects in tumor-reactive T cells. This study highlights critical distinctions between how endogenous T cells that evolve in vivo, and engineered T cells with previously acquired effector activity, respond to modifications of the tumor microenvironment.

A BODIPY-Based Donor/Donor-Acceptor System: Towards Highly Efficient Long-Wavelength-Excitable Near-IR Polymer Dots with Narrow and Strong Absorption Features.

Bright long-wavelength-excitable semiconducting polymer dots (LWE-Pdots) are highly desirable for in vivo imaging and multiplexed in vitro bioassays. LWE-Pdots have been obtained by incorporating a near-infrared (NIR) emitter into the backbone of a polymer host to develop a binary donor-acceptor (D-A) system. However, they usually suffer from severe concentration quenching and a trade-off between fluorescence quantum yield (Φf ) and absorption cross-section (σ). Herein, we describe a ternary component (D1 /D2 -A) strategy to achieve ultrabright, green laser-excitable Pdots with narrow-band NIR emission by introducing a BODIPY-based assistant polymer donor as D1 . The D1 /D2 -A Pdots possess improved Φf and σ compared to corresponding binary D2 -A Pdots. Their Φf is as high as 40.2 %, one of the most efficient NIR Pdots reported. The D1 /D2 -A Pdots show ultrahigh single-particle brightness, 83-fold brighter than Qdot 705 when excited by a 532 nm laser. When injected into mice, higher contrast in vivo tumor imaging was achieved using the ternary Pdots versus the binary D-A Pdots.

Phase IB/II Randomized Study of FOLFIRINOX Plus Pegylated Recombinant Human Hyaluronidase Versus FOLFIRINOX Alone in Patients With Metastatic Pancreatic Adenocarcinoma: SWOG S1313.

PURPOSE: Pegylated recombinant human hyaluronidase (PEGPH20) degrades hyaluronan (HA) and, in combination with chemotherapy, prolongs survival in preclinical models. The activity of PEGPH20 with modified fluorouracil, leucovorin, irinotecan, and oxaliplatin (mFOLFIRINOX) was evaluated in patients with metastatic pancreatic cancer (mPC). MATERIALS AND METHODS: Patients had untreated mPC, a performance status of 0 to 1, and adequate organ function. Tumor HA status was not required for eligibility. After a phase Ib dose-finding study of mFOLFIRINOX plus PEGPH20, the phase II open-label study randomly assigned patients (1:1) to the combination arm or to mFOLFIRINOX alone (n = 138). The primary end point was overall survival (OS). RESULTS: PEGPH20 dosages of 3 µg/kg every 2 weeks were more tolerable than twice-weekly dosages used in the phase I study, so 3 µg/kg every 2 weeks was the phase II dosage. An amendment instituted enoxaparin prophylaxis in the PEGPH20 combination arm as a result of increased thromboembolic (TE) events. The planned interim futility analysis when 35 deaths (of 103 analyzable patients) occurred resulted in an OS hazard ratio (HR) of 2.07 that favored the control arm, and the study was closed to accrual. The treatment-related grade 3 to 4 toxicity was significantly increased in the PEGPH20 combination arm relative to control (odds ratio, 2.7; 95% CI, 1.1 to 7.1). The median OS in the mFOLFIRINOX arm was 14.4 months (95% CI, 10.1 to 15.7 months) versus 7.7 months (95% CI, 4.6 to 9.3 months) in the PEGPH20 combination arm. CONCLUSION: Addition of PEGPH20 to mFOLFIRINOX seems to be detrimental in patients unselected for tumor HA status. This combination caused increased toxicity (mostly GI and TE events) and resulted in decreased treatment duration compared with mFOLFIRINOX alone. The median OS in the mFOLFIRINOX control arm (14.4 months) is, to our knowledge, the longest yet reported and can be considered for patients with good PS.

Fibroblasts in Pancreatic Ductal Adenocarcinoma: Biological Mechanisms and Therapeutic Targets.

The desmoplastic reaction of pancreas cancer may begin as a wound healing response to the nascent neoplasm, but it soon creates an insidious shelter that can sustain the growing tumor and rebuff therapy. Among the many cell types subverted by transformed epithelial cells, fibroblasts are recruited and activated to lay a foundation of extracellular matrix proteins and glycosaminoglycans that alter tumor biophysics and signaling. Their near-universal presence in pancreas cancer and ostensible support of disease progression make fibroblasts attractive therapeutic targets. More recently, however, it has also become apparent that diverse subpopulations of fibroblasts with distinct phenotypes and secretomes inhabit the stroma, and that targeted depletion of particular fibroblast subsets could either provide substantial therapeutic benefit or accelerate disease progression. An improved characterization of these fibroblast subtypes, along with their potential relationships to tumor subtypes and mutational repertoires, is needed in order to make anti-fibroblast therapies clinically viable.

Mesenchymal Cell Plasticity and Perfidy in Epithelial Malignancy.

Stromal complicity in epithelial carcinogenesis contributes to immune suppression and treatment resistance, but not all cancer-associated fibroblasts (CAFs) are bad actors. Identifying and targeting protumorigenic CAFs while preserving their antitumorigenic counterparts is the challenge. The risk is the possibility of making things worse; the reward is the potential to transform the care of and prognosis for patients with solid tumors.

Hyperthermia-enhanced targeted drug delivery using magnetic resonance-guided focussed ultrasound: a pre-clinical study in a genetic model of pancreatic cancer.

PURPOSE: The lack of effective treatment options for pancreatic cancer has led to a 5-year survival rate of just 8%. Here, we evaluate the ability to enhance targeted drug delivery using mild hyperthermia in combination with the systemic administration of a low-temperature sensitive liposomal formulation of doxorubicin (LTSL-Dox) using a relevant model for pancreas cancer. MATERIALS AND METHODS: Experiments were performed in a genetically engineered mouse model of pancreatic cancer (KPC mice: LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre). LTSL-Dox or free doxorubicin (Dox) was administered via a tail vein catheter. A clinical magnetic resonance-guided high intensity focussed ultrasound (MR-HIFU) system was used to plan treatment, apply the HIFU-induce hyperthermia and monitor therapy. Post-therapy, total Dox concentration in tumour tissue was determined by HPLC and confirmed with fluorescence microscopy. RESULTS: Localized hyperthermia was successfully applied and monitored with a clinical MR-HIFU system. The mild hyperthermia heating algorithm administered by the MR-HIFU system resulted in homogenous heating within the region of interest. MR-HIFU, in combination with LTSL-Dox, resulted in a 23-fold increase in the localised drug concentration and nuclear uptake of doxorubicin within the tumour tissue of KPC mice compared to LTSL-Dox alone. Hyperthermia, in combination with free Dox, resulted in a 2-fold increase compared to Dox alone. CONCLUSION: This study demonstrates that HIFU-induced hyperthermia in combination with LTSL-Dox can be a non-invasive and effective method in enhancing the localised delivery and penetration of doxorubicin into pancreatic tumours.

HALO 202: Randomized Phase II Study of PEGPH20 Plus Nab-Paclitaxel/Gemcitabine Versus Nab-Paclitaxel/Gemcitabine in Patients With Untreated, Metastatic Pancreatic Ductal Adenocarcinoma.

Purpose Metastatic pancreatic ductal adenocarcinoma is characterized by excessive hyaluronan (HA) accumulation in the tumor microenvironment, elevating interstitial pressure and impairing perfusion. Preclinical studies demonstrated pegvorhyaluronidase alfa (PEGPH20) degrades HA, thereby increasing drug delivery. Patients and Methods Patients with previously untreated metastatic pancreatic ductal adenocarcinoma were randomly assigned to treatment with PEGPH20 plus nab-paclitaxel/gemcitabine (PAG) or nab-paclitaxel/gemcitabine (AG). Tumor HA levels were measured retrospectively using a novel affinity histochemistry assay. Primary end points were progression-free survival (PFS; overall) and thromboembolic (TE) event rate. Secondary end points included overall survival, PFS by HA level, and objective response rate. An early imbalance in TE events in the PAG arm led to a clinical hold; thereafter, patients with TE events were excluded and enoxaparin prophylaxis was initiated. Results A total of 279 patients were randomly assigned; 246 had HA data; 231 were evaluable for efficacy; 84 (34%) had HA-high tumors (ie, extracellular matrix HA staining ≥ 50% of tumor surface at any intensity). PFS was significantly improved with PAG treatment overall (hazard ratio [HR], 0.73; 95% CI, 0.53 to 1.00; P = .049) and for patients with HA-high tumors (HR, 0.51; 95% CI, 0.26 to 1.00; P = .048). In patients with HA-high tumors (PAG v AG), the objective response rate was 45% versus 31%, and median overall survival was 11.5 versus 8.5 months (HR, 0.96; 95% CI, 0.57 to 1.61). The most common treatment-related grade 3/4 adverse events with significant differences between arms (PAG v AG) included muscle spasms (13% v 1%), neutropenia (29% v 18%), and myalgia (5% v 0%). TE events were comparable after enoxaparin initiation (14% PAG v 10% AG). Conclusion This study met its primary end points of PFS and TE event rate. The largest improvement in PFS was observed in patients with HA-high tumors who received PAG. A similar TE event rate was observed between the treatment groups in stage 2 of the trial.

Understanding Disease Biology and Informing the Management of Pancreas Cancer With Preclinical Model Systems.

Recent advances in cytotoxic therapies for pancreatic ductal adenocarcinoma (PDA) are overshadowed by stalled clinical progress of more targeted strategies, the vast majority of which have failed in clinical trials. Inability to translate preclinical promise into clinical efficacy derives, in part, from imperfect disease modeling and mismatches between preclinical and clinical study design and execution. Into these gaps fall our patients who enter the clinical trial landscape expectantly and bear the brunt of its inadequacies. If improving patient survival is paramount, then it must be acknowledged that the failure of a phase III trial represents a larger failure of all of the work that preceded it. Repeated failures suggest a need to reappraise the current preclinical-to-clinical apparatus. Exceptional models of PDA are now available to researchers, and the first steps toward a new era of success can begin with improved selection and application of these systems. We discuss the key features of the major preclinical platforms for PDA and propose a paradigm for rigorous interrogation of prospective therapies.

T-cell Localization, Activation, and Clonal Expansion in Human Pancreatic Ductal Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDA) is a lethal malignancy resistant to most therapies, including immune checkpoint blockade. To elucidate mechanisms of immunotherapy resistance, we assessed immune parameters in resected human PDA. We demonstrate significant interpatient variability in T-cell number, localization, and phenotype. CD8+ T cells, Foxp3+ regulatory T cells, and PD-1+ and PD-L1+ cells were preferentially enriched in tertiary lymphoid structures that were found in most tumors compared with stroma and tumor cell nests. Tumors containing more CD8+ T cells also had increased granulocytes, CD163+ (M2 immunosuppressive phenotype) macrophages, and FOXP3+ regulatory T cells. PD-L1 was rare on tumor cells, but was expressed by CD163+ macrophages and an additional stromal cell subset commonly found clustered together adjacent to tumor epithelium. The majority of tumoral CD8+ T cells did not express molecules suggestive of recent T-cell receptor (TCR) signaling. However, 41BB+PD-1+ T cells were still significantly enriched in tumors compared with circulation. Tumoral CD8+PD-1+ T cells commonly expressed additional inhibitory receptors, yet were mostly T-BEThi and EOMESlo, consistent with a less terminally exhausted state. Analysis of gene expression and rearranged TCR genes by deep sequencing suggested most patients have a limited tumor-reactive T-cell response. Multiplex immunohistochemistry revealed variable T-cell infiltration based on abundance and location, which may result in different mechanisms of immunotherapy resistance. Overall, the data support the need for therapies that either induce endogenous, or provide engineered, tumor-specific T-cell responses, and concurrently relieve suppressive mechanisms operative at the tumor site. Cancer Immunol Res; 5(11); 978-91. ©2017 AACR.