Real-world overall survival of patients diagnosed with recurrent versus de novo metastatic pancreatic ductal adenocarcinoma (PDAC)

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Background: PDAC is a lethal malignancy which accounted for the third most cancer related deaths in 2020. Patients (pts) who are initially diagnosed with stage I-III PDAC have a 5-year relative survival of 13.3 – 39.4%; those with metastatic disease at diagnosis have a 5-year relative survival of 2.9%. Limited data are published comparing the outcomes of pts with stage I-III who develop metastases (recurrent) compared to pts with de novo mPDAC (de novo). This analysis seeks to compare demographic, clinical characteristics, and survival outcomes of pts with recurrent versus de novo mPDAC in a community oncology setting. Methods: Using the Flatiron Health database, a retrospective observational study was conducted abstracting deidentified data from ≥280 US cancer clinics. Pts with mPDAC diagnosed from 01/2016 to 08/2020 with a known stage at initial diagnosis were included. Pts were stratified based on initial stage at diagnosis. Median overall survival (OS) from time of metastasis was derived using Kaplan-Meier analysis. Unadjusted and multivariable Cox proportional hazards models were used to compare survival between recurrent and de novo cohorts. Results: N = 6,543 pts analyzed; 70.1% (n = 4,586) had de novo mPDAC and 29.9% (n = 1,957) had recurrent mPDAC. Median age at time of metastasis was similar for both cohorts: 69 years (IQR: 62 – 76). The most common site of primary tumor location was head for both cohorts (recurrent mPDAC: 69.8%; de novo mPDAC: 40.3%). Approximately 45% of pts with recurrent mPDAC underwent a Whipple procedure (pre diagnosis of metastasis). A similar proportion of pts in both cohorts received treatment in the metastatic setting (recurrent mPDAC: 74.3%; de novo mPDAC: 77.3%). Pts with recurrent mPDAC had a longer median OS compared to the de novo cohort: 8.0 months (95% CI: 7.5 – 8.6) versus 6.1 (95% CI: 5.7 – 6.4) [unadjusted hazard ratio (HR): 0.79 (95% CI: 0.74 – 0.84); adjusted HR: 0.73 (0.68 – 0.78), p < 0.0001]. Conclusions: The results of this real-world study indicate that pts with recurrent mPDAC are more likely to have a head primary and to experience longer OS from time of metastasis than those with de novo mPDAC. These data suggest stratification for clinical trial enrollment for recurrent vs de novo is necessitated.

Association of Ablative Radiation Therapy With Survival Among Patients With Inoperable Pancreatic Cancer

Importance

Surgical resection has been considered the only curative option for patients with pancreatic cancer. Nonoperative local treatment options that can provide a similar benefit are needed. Emerging radiation techniques that address organ motion have enabled curative radiation doses to be given in patients with inoperable disease.

Objective

To determine the association of hypofractionated ablative radiation therapy (A-RT) with survival for patients with locally advanced pancreatic cancer (LAPC) treated with a novel radiation planning and delivery technique.

Design, Setting, and Participants

This cohort study included 119 consecutive patients treated with A-RT between June 2016 and February 2019 and enrolled in a prospectively maintained database. Patients were treated with a standardized technique within a large academic cancer center regional network. All patients with localized, unresectable, or medically inoperable pancreatic cancer with tumors of any size and less than 5 cm luminal abutment with the primary tumor were eligible.

Interventions

Ablative RT (98 Gy biologically effective dose) was delivered using standard equipment. Respiratory gating, soft tissue image guidance, and selective adaptive planning were used to address organ motion and limit the dose to surrounding luminal organs.

Main Outcomes and Measures

The primary outcome was overall survival (OS). Secondary outcomes included incidence of local progression and progression-free survival.

Results

Between 2016 and 2019, 119 patients (59 men, median age 67 years) received A-RT, including 99 with T3/T4 and 53 with node-positive disease, with a median carbohydrate antigen 19-9 (CA19-9) level greater than 167 U/mL. Most (116 [97.5%]) received induction chemotherapy for a median of 4 months (0.5-18.4). Median OS from diagnosis and A-RT were 26.8 and 18.4 months, respectively. Respective 12- and 24-month OS from A-RT were 74% (95% CI, 66%-83%) and 38% (95% CI, 27%-52%). Twelve- and 24-month cumulative incidence of locoregional failure were 17.6% (95% CI, 10.4%-24.9%) and 32.8% (95% CI, 21.6%-44.1%), respectively. Postinduction CA19-9 decline was associated with improved locoregional control and survival. Grade 3 upper gastrointestinal bleeding occurred in 10 patients (8%) with no grade 4 to 5 events.

Conclusions and Relevance

This cohort study of patients with inoperable LAPC found that A-RT following multiagent induction therapy for LAPC was associated with durable locoregional tumor control and favorable survival. Prospective randomized trials in patients with LAPC are warranted.

Leptomeningeal disease in pancreas ductal adenocarcinoma: A manifestation of longevity

BACKGROUND

/Objectives: Pancreatic adenocarcinoma (PDAC) metastatic to the leptomeninges is a rare and lethal event. Leptomeningeal disease (LMD) research is limited in PDAC, and insights into clinical descriptors, possible disease predictors, and treatment strategies is necessitated.

METHODS

Memorial Sloan Kettering databases were queried with Institutional Review Board approval to identify patients with LMD and PDAC treated between January 2000 and June 2020. Medical record review was used to abstract clinical, genomic, pathologic, and radiographic data. Overall survival was calculated from date of PDAC diagnosis to date of death. Previously published literature on LMD from PDAC was reviewed.

RESULTS

Four patients with LMD from PDAC were identified, two males and two females. Age at diagnosis ranged from 57 to 68 years. All four patients had predominant lung metastasis and a relatively low burden of intra-abdominal disease. Somatic testing indicated alterations typical of PDAC and no PDAC defining pathogenic germline mutations were identified. An extended clinical course prior to LMD diagnosis was observed in all patients, ranging from 16 to 148 months. Upon diagnosis of LMD, three patients elected for supportive care and one patient received a limited course of craniospinal radiation. The median survival following diagnosis of LMD was 1.6 months (range 0.5-2.8 months).

CONCLUSIONS

LMD from PDAC is a rare occurrence that may be more frequent in patients with lung metastasis and/or a more indolent clinical course. Following diagnosis of LMD, prognosis is poor, and survival is short. New treatment strategies for this manifestation of PDAC are needed.

Population-based, real-world prognostic factors related to survival among patients with metastatic pancreatic ductal adenocarcinoma (mPDAC)

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Background: Pancreatic cancer is expected to be the third deadliest cancer in the US in 2020. Many real-world studies of pts with mPDAC are restricted to single centers, limiting the generalizability of the insights they generate. There is a need to understand prognostic factors of survival in a broader setting to aid in tailoring treatment strategies for pts. This study aimed to identify important population-based predictors related to survival among pts diagnosed with mPDAC. Methods: Data were extracted for pts diagnosed with mPDAC between Jan 2017 and Dec 2019 from the Flatiron Health database. Predictive models for overall survival from the start of each treatment were developed using multivariable Cox proportional hazards regression. Treatment specific predictive models were generated for pts treated with first line (1L) gemcitabine + nab-paclitaxel (GNP), 1L FOLFIRINOX, 1L gemcitabine monotherapy (gem-mono), and 2L liposomal irinotecan-based regimens. The holdout method was used for cross-validation, splitting the data into 70% training / 30% validation. Age at diagnosis, sex, body mass index, smoking status, and ECOG performance score (PS) were included in all models due to clinical importance. Demographic, clinical characteristics, hematological labs, liver function tests (LFTs), and serum bilirubin levels were assessed for inclusion into the models. Uno’s concordance statistic (c-statistic) was used to assess the predictive accuracy of the models. Results: Of the 3,572 pts included in the study, 44% (n = 1,557) received 1L GNP, 27% (n = 954) received 1L FOLFIRINOX, 7% (n = 265) received gem-mono, and 22% (n = 796) received other regimens. 38% (n = 1,345) pts received 2L and of those, 17% (n = 222) received liposomal irinotecan-based regimens. Among all 1L pts, the following were included in the final model: prior surgery, white blood cell (WBC) counts, serum albumin, LFTs (ALP and ALT), serum bilirubin, and ascites (c-statistic: 0.65). The model for pts treated with GNP differed from the overall model via the addition of neutrophil counts and removal of serum bilirubin and ascites (c-statistic: 0.67). Stage at initial diagnosis was included in the model only for pts treated with 1L FOLFIRINOX (c-statistic: 0.68). Among pts treated with gem-mono the LFTs were not included in the model (c-statistic: 0.78). ALP, serum albumin, and WBC counts were important predictors of survival among pts treated with 2L liposomal irinotecan-based regimens (c-statistic: 0.70). Across all regimens the strongest predictors of survival were ECOG PS, serum albumin, and ALP. Conclusions: In one of the largest contemporary real-world studies of patients with mPDAC to date, important population predictors of survival in pts receiving systemic treatment were identified. Further validation studies are needed to understand the generalizability of these results.

Reducing nihilism in metastatic pancreatic ductal adenocarcinoma: Treatment, sequencing, and effects on survival outcomes

BACKGROUND

Real-world practice patterns, treatment sequencing, and outcomes in patients with metastatic pancreatic cancer remain unclear. Previous research indicates that the likelihood of patients with metastatic pancreatic cancer receiving or continuing cancer-directed therapy is low-a phenomenon called nihilism. This retrospective, descriptive analysis examined clinical characteristics, treatment patterns, and outcomes for patients with metastatic pancreatic ductal adenocarcinoma (mPDAC).

METHODS

Treatment patterns were examined using electronic health records from the Flatiron Health database covering the period from January 1, 2014, to June 30, 2019. Real-world overall survival [rwOS]) was compared for a subgroup of patients receiving treatment and a matched subgroup not receiving treatment.

RESULTS

Of 7666 patients, 5687 (74.2%) received at least one line of systemic therapy. A greater proportion of patients receiving treatment than not receiving treatment had an initial diagnosis of stage IV disease (68.8% vs 61.2%, respectively). Among patients receiving an initial therapy, fewer than half (38.2%; 2174/5687) received second-line treatment, mostly because they died, and only 34.3% (745/2174) of those receiving second-line treatment advanced to third-line treatment. The rwOS for patients receiving at least one line of systemic therapy was 8.1 months versus 2.6 months for matched patients not receiving treatment (hazard ratio, 0.41; 95% confidence interval, 0.38-0.45; 1470 patients per group).

CONCLUSIONS

Systemic therapy provided significant clinical benefit for patients who were eligible and chose to receive it, particularly when treatment was consistent with guideline recommendations. The large proportion of patients initiating treatment suggests that nihilism with mPDAC is diminishing.

Abstract LB-263: Pancreatic cancer prognosis is predicted by chromatin accessibility microarray

Personalized therapy is the future of cancer care. Almost half of the cancer patients do not respond to chemotherapy. For instance, pancreatic ductal adenocarcinoma (PDAC) patients with the limited local disease and with no detectable metastasis typically have their primary tumor surgically resected, but the disease recurs in approximately 50% of cases within 1 year of surgery, in spite of adjuvant chemotherapy. Although gene expression signatures correlating prognosis have been described in PDAC, the therapeutic utility of these signatures has been limited based in part on a large number of genes displaying an altered expression. On the other hand, regulatory regions common to these genes might be amenable to collective epigenetic reprogramming using epigenetic drugs. We interrogated genome-wide chromatin accessibility using Assay for Transposase-Accessible Chromatin sequencing (ATAC-seq) on EpCAM+ PDAC malignant cells sorted from a cohort of 54 treatment-naïve resected tumors, in hopes of defining a tumor-intrinsic chromatin signature associated with recurrence. We discovered a signature of 1092 loci that were differentially accessible between recurrent (disease-free survival (DFS) &lt; 1 year) and non-recurrent patients (DFS &gt; 1 year). Through transcription factor (TF) binding motif analysis, we identified candidate TFs whose accessible motifs were differentially associated with recurrence. Nuclear localization of two such TFs, ZKSCAN1 and HNF1b, were assessed by immunostaining on tissue microarrays (TMA) representing 40 out of 54 patients. Nuclear staining of HNF1b was strong in tumor tissue from non-recurrent patients and weak or absent in recurrent patients, but ZKSCAN1 staining patterns were not significantly associated with recurrence. In a TMA representing an independent PDAC cohort (n=97) preselected for 52 long (OS 6 years)- and 45 short (OS 6 months)- term survivors, the number of nuclear positive cells for HNF1b was 52-fold higher in the long-term compared to the short-term survivors and that for ZKSCAN1 was 5.3-fold higher in the short-term compared to the long-term survivors. We further validated the 1092 chromatin accessibility signature by a novel microarray-based platform technology that we termed “ATAC-Array”, where the differentially accessible regions from the signatures were probed on a glass slide and then hybridized with fluorescent-labeled ATAC-libraries. This is a cost-effective, easy-to-use platform technology avoiding the time and cost of next-generation ATAC library sequencing. ATAC-array is the only microarray that reads chromatin accessibility. We have compared ATAC-array side-by-side with ATAC-seq (n=30) and found significant correlation (Pearson's median r= 0.64, range= 0.50- 0.77). By performing ATAC-array on the PDAC cohort (n=38), we have independently re-classified the patients who recurred early and the ones who did not (Gehan-Breslow-Wilcoxon test p=0.0076). ATAC-array, as the technology itself, has enormous potential for a wide range of applications, and we propose to develop it as a clinically validated theragnostic tool to predict and stratify cancer patients for epigenetic therapy.

Citation Format: Surajit Dhara, Sagar Chhangawala, Himanshu Chintalapudi, Alexandra L. Massa, Victoria Aveson, Gokce Askan, Liguo Zhang, Remy Nicolle, Alvin P. Makohon-Moore, Smrita Sinha, Jiang Gui, Richard Moffitt, Kenneth H. Yu, Vinod Balachandran, Rohit Chandwani, Christina Leslie, Steven D. Leach. Pancreatic cancer prognosis is predicted by chromatin accessibility microarray [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-263.

Predicting Gemcitabine Delivery by 18F-FAC PET in Murine Models of Pancreatic Cancer

¹⁸F-FAC (2'-deoxy-2'-¹⁸F-fluoro-β-d-arabinofuranosylcytosine) has close structural similarity to gemcitabine and thus offers the potential to image drug delivery to tumors. We compared tumor ¹⁸F-FAC PET images with ¹⁴C-gemcitabine levels, established ex vivo, in 3 mouse models of pancreatic cancer. We further modified tumor gemcitabine levels with injectable PEGylated recombinant human hyaluronidase (PEGPH20) to test whether changes in gemcitabine would be tracked by ¹⁸F-FAC. Methods: ¹⁸F-FAC was synthesized as described previously. Three patient-derived xenograft (PDX) models were grown in the flanks of NSG mice. Mice were given PEGPH20 or vehicle intravenously 24 h before coinjection of ¹⁸F-FAC and ¹⁴C-gemcitabine. Animals were euthanized and imaged 1 h after tracer administration. Tumor and muscle uptake of both ¹⁸F-FAC and ¹⁴C-gemcitabine was obtained ex vivo. The efficacy of PEPGPH20 was validated through staining with hyaluronic acid binding protein. Additionally, an organoid culture, initiated from a KPC (Pdx-1 Cre LSL-Kras^G12D LSL-p53^R172H) tumor, was used to generate orthotopically growing tumors in C57BL/6J mice, and these tumors were then serially transplanted. Animals were injected with PEGPH20 and ¹⁴C-gemcitabine as described above to validate increased drug uptake by ex vivo assay. PET/MR images were obtained using a PET insert on a 7-T MR scanner. Animals were imaged immediately before injection with PEGPH20 and again 24 h later. Results: Tumor-to-muscle ratios of ¹⁴C-gemcitabine and ¹⁸F-FAC correlated well across all PDX models and treatments (R ² = 0.78). There was a significant increase in the tumor PET signal in PEGPH20-treated PDX animals, and this signal was matched in ex vivo counts for 2 of 3 models. In KPC-derived tumors, PEGPH20 raised ¹⁴C-gemcitabine levels (tumor-to-muscle ratio of 1.9 vs. 2.4, control vs. treated, P = 0.013). PET/MR ¹⁸F-FAC images showed a 12% increase in tumor ¹⁸F-FAC uptake after PEGPH20 treatment (P = 0.023). PEGPH20-treated animals uniformly displayed clear reductions in hyaluronic acid staining. Conclusion: ¹⁸F-FAC PET was shown to be a good surrogate for gemcitabine uptake and, when combined with MR, to successfully determine drug uptake in tumors growing in the pancreas. PEGPH20 had moderate effects on tumor uptake of gemcitabine.

Genomic Methods Identify Homologous Recombination Deficiency in Pancreas Adenocarcinoma and Optimize Treatment Selection

PURPOSE

Genomic methods can identify homologous recombination deficiency (HRD). Rigorous evaluation of their outcome association to DNA damage response-targeted therapies like platinum in pancreatic ductal adenocarcinoma (PDAC) is essential in maximizing therapeutic outcome.

EXPERIMENTAL DESIGN

We evaluated progression-free survival (PFS) and overall survival (OS) of patients with advanced-stage PDAC, who had both germline- and somatic-targeted gene sequencing. Homologous recombination gene mutations (HRm) were evaluated: BRCA1, BRCA2, PALB2, ATM, BAP1, BARD1, BLM, BRIP1, CHEK2, FAM175A, FANCA, FANCC, NBN, RAD50, RAD51, RAD51C, and RTEL1 HRm status was grouped as: (i) germline versus somatic; (ii) core (BRCAs and PALB2) versus non-core (other HRm); and (iii) monoallelic versus biallelic. Genomic instability was compared using large-scale state transition, signature 3, and tumor mutation burden.

RESULTS

Among 262 patients, 50 (19%) had HRD (15% germline and 4% somatic). Both groups were analyzed together due to lack of difference in their genomic instability and outcome. Median [95% confidence interval (CI)] follow-up was 21.9 (1.4-57.0) months. Median OS and PFS were 15.5 (14.6-19) and 7 (6.1-8.1) months, respectively. Patients with HRD had improved PFS compared with no HRD when treated with first-line (1L) platinum [HR, 0.44 (95% CI: 0.29-0.67); P < 0.01], but not with 1L-non-platinum. Multivariate analysis showed HRD patients had improved OS regardless of their first-line treatment, but most had platinum exposure during their course. Biallelic HRm (11%) and core HRm (12%) had higher genomic instability, which translated to improved PFS on first-line platinum (1L-platinum) versus 1L-non-platinum.

CONCLUSIONS

Pathogenic HRm identifies HRD in patients with PDAC with the best outcome when treated with 1L-platinum. Biallelic HRm and core HRm further enriched benefit from 1L-platinum from HRD.

Alterations in driver genes are predictive of survival in patients with resected pancreatic ductal adenocarcinoma

BACKGROUND

KRAS, TP53, CDKN2A, and SMAD4 are established driver genes in pancreatic ductal adenocarcinoma (PDAC). This study was aimed at determining whether the mutational status of driver genes and those involved in DNA repair pathways are associated with clinical outcomes for individuals who undergo resection.

METHODS

Eligible individuals were those who underwent resection of PDAC and consented to targeted sequencing of their primary tumor via Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT). Genomic alterations were determined on the basis of MSK-IMPACT results from formalin-fixed, paraffin-embedded samples. Associations between genomic alterations and clinical outcomes were assessed.

RESULTS

Targeted sequencing was performed on 283 primary tumors resected between 2004 and 2017. The median follow-up was 23 months among survivors. Alterations in KRAS and TP53 were associated with worse overall survival (OS) in comparison to wild type (median for KRAS, 38.8 months [95% CI, 33.0-45.5 months] vs 91.0 months [95% CI, 34.8 months to not available (NA)]; P = .043; median for TP53, 37.4 months [95% CI, 32.1-42.8 months] vs 65.0 months [95% CI, 33.0 months to NA]; P = .035). KRAS G12D mutations were associated with worse OS (median, 31.6 months [95% CI, 25.3-45.5 months] vs 39.2 months [95% CI, 37.4-75.2 months]; P = .012). TP53 truncating mutations (median, 39.6 months [95% CI, 32.4-75.2 months] vs 33.9 months [95% CI, 24.0-39.0 months]; P = .020) and those associated with loss of heterozygosity (median, 26.6 months [95% CI, 21.6-44.2 months] vs 39.2 months [95% CI, 34.5-49.1 months]; P = .048) had decreased OS. TP53 alterations were independently associated with OS in a multivariate analysis (hazard ratio, 1.54; 95% CI, 1.01-2.33; P = .042). Individuals with germline alterations in homologous recombination deficiency (HRD) genes had improved OS in comparison with those without them (median, not reached vs 37.0 months; 95% CI, 33.0-49.8 months; P = .035).

CONCLUSIONS

In patients with resected PDAC, genomic alterations in KRAS and TP53 are associated with worse outcomes, whereas alterations in HRD genes are associated with a favorable prognosis. Further studies are needed to better define these alterations as biomarkers in resected PDAC.

A multicenter chart review study of patients with metastatic pancreatic ductal adenocarcinoma receiving liposomal irinotecan after gemcitabine-based therapy

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Background: Real-world data allows healthcare decision-makers to assess and manage therapeutic and economic options for patients, including those who would and would not have met eligibility criteria for randomized control trials (RCT) and are instead managed under usual care. This retrospective multi-academic center chart review study describes real-world characteristics and outcomes of US patients receiving liposomal irinotecan for the management of metastatic pancreatic ductal adenocarcinoma (mPDAC). Methods: Patients with mPDAC treated with liposomal irinotecan were eligible. Initiation of liposomal irinotecan defined index date; covariates assessed included clinical characteristics and treatment patterns; real-world overall survival (rwOS) was assessed via Kaplan-Meier methodology. The target enrollment is 300 patients. The study centers included were Memorial Sloan Kettering Cancer Center, Cedars-Sinai Medical Center, Emory Winship Cancer Institute, Houston Methodist Cancer Center, Henry Ford Cancer Institute, and University of Pittsburgh Medical Center. Results: Data on 26 patients were available for initial analyses. Mean age was 68 years; 58% were female and 65% Caucasian. 54% of patients had stage IV disease at first diagnosis, and 17%, 65%, and 17% had index ECOG score of 0, 1, and 2, respectively. Common genetic mutations include KRAS (40%) and TP53 (40%). Prior to liposomal irinotecan, treatments received for metastatic disease include gemcitabine+nab-paclitaxel (77%) and fluorouracil (5-FU)/leucovorin (LV)+irinotecan+oxaliplatin (19%). Patients had received 0 (12%), 1 (23%), and ≥2 (65%) lines of therapy in the metastatic setting prior to liposomal irinotecan. Mean duration of liposomal irinotecan use was 3.0 months; liposomal irinotecan was mostly received with 5-FU (23%) or 5-FU/LV (69%). Median rwOS was 4.9 months (95% CI: 3.0, 6.3). Conclusions: Real-world data of the first 26 patients in this study show patients treated with liposomal irinotecan are older, sicker, and have had more lines of therapy than previously reported in RCT data.

Landscape of DNA-damage-repair/homologous recombination deficiency (DDR/HRD) in hepatopancreaticobiliary (HPB) cancers

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Background: Biallelic HR-gene mutations (HRm) confer HRD and sensitivity to DDR-targeted therapies including platinum and PARPi in pancreatic cancer (PDAC). The landscape of DDR/HRD phenotypes in HPB cancers and their clinical implication is yet to be evaluated, the subject of this effort. Methods: Hybrid capture-based comprehensive genomic profiling was performed in a CLIA-certified, CAP-accredited lab (Foundation Medicine, Inc.) on up to 395 genes, including the HR-genes ( BRCA1/2, PALB2, RAD50/51B/C/D, MRE11, ATRX, ATR, ATM, BAP1, BRIP1, CHEK2, NBN, and FANCA). Putative DDR/HRD phenotype was assessed using percent genome under LOH (gLOH) (PMID: 28916367). Variant zygosity was assessed as previously described (PMID: 29415044). From an independent PDAC subgroup among HPB cancers, we evaluated their outcomes on first-line platinum. Results: From a total of 11,174 tumors, pathogenic DDR/HRm were identified in 18% (1980/11174) of HPB cancers, 15% (863/5941) of PDAC, 25% (744/2998) of cholangiocarcinoma, 15% (141/958) of hepatocellular carcinoma, and 17% (152/873) of gallbladder carcinoma. We observed a majority (63%) of DDR/HRm with LOH. Rigorous filtering for tumor purity and copy number quality metrics yielded 34% (4051/11774) cases evaluable. The median gLOH of any biallelic DDR/HRm was 12.9% compared to 8.8% in no DDR/HRm (p=5.7E-33). Strength of the association varied by gene, with the strongest association in BRCA1 (22.3, p=1.5E-10), BRCA2 (20.1, p=1.7E-35), RAD51C (16.7, p=7.8E-4), PALB2 (16.4, p=1.4E-5), BRIP1 (14.3, p=0.02), RAD51B (13.7, p=0.02), and ATM (13.6, p=7.7E-12) (Table). Most other DDR/HR-genes and monoallelic DDR/HRm had weak gLOH. PDAC accounted for 60% of this HPB dataset. In an independent dataset of PDAC at MSK (n=262), biallelic DDR/HRm patients (n=29, 11%) had mostly germline mutations and had significantly improved median PFS on first-line platinum vs. non-platinum (13.3 [95%CI: 9.57-NR] vs 3.8 [95%CI: 2.79-NR] months, p<0.0001). Conclusions: Biallelic DDR/HRm is a distinct population of HPB cancers beyond PDAC and may confer better phenotype in DDR-targeted treatment. Further independent validation is underway. [Table: see text]

Error-free, automated data integration of exosome cargo protein data with extensive clinical data in an ongoing, multi-omic translational research study

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Background: Major advances in understanding the biology of cancer have come from genomic analysis of tumor and normal tissue. Integrating extensive patient-related data with deep analysis of omic data is crucial to informing omic data interpretation. Currently, such integrations are a highly manual, asynchronous, and costly process as well as error-prone and time-consuming. To develop new blood assays that may detect very early stage PDAC, a multi-omic investigation with deep clinical annotation is needed. Using pilot data from an on-going study, we test a new platform allowing automated error-free integration of an extensive clinical database with extensive omic data. Methods: Demographic, clinical, family pedigree and pathology data were collected on the Rave EDC platform. Exosomes were purified from 46 plasma samples from 14 controls and 24 PDAC patients and cargo proteins were quantified via SILAC. The Rave Omics platform was used to ingest and integrate clinical and omic data, run quality checks and generate integrated clinical-omic datasets. Data fidelity was validated by systematically computing differences between corresponding values in the source flies with those present in the extracted data object (integrated data). The root mean squared error (RMSE) was calculated for numeric values in each sample. Additional validation was conducted by manual inspection to ascertain data integrity. Results: We demonstrated automatic integration, without human intervention, of a subset of the clinical data and all available SILAC data into an analysis-ready data object. Data transfer was completely faithful, with 100% concordance between the source and the integrated data without loss of features. All proteins (n = 1515) and clinical variables (n = 64) were imported. Their nomenclature and corresponding sample values (n = 69690) and clinical values (n = 2432) matched exactly between datasets. In all samples, the RMSE was exactly zero, indicating no deviation between data sources. Conclusions: We demonstrated that automatic, efficient, and reliable integration of clinical-omic data is achievable during an in-flight PDAC trial. Automatic exploratory analytics supporting biomarker discovery are currently being used to uncover associations between omic and clinical features. The Rave Omics platform is disease-agnostic and we plan to expand to trials of varying size, indication, and completion status where systematic, automated integration of clinical and (multi)omic data is needed.

Randomized, Multicenter, Phase II Trial of Gemcitabine and Cisplatin With or Without Veliparib in Patients With Pancreas Adenocarcinoma and a Germline BRCA/PALB2 Mutation

PURPOSE

Five percent to 9% of pancreatic ductal adenocarcinomas (PDACs) develop in patients with a germline BRCA1/2 or PALB2 (gBRCA/PALB2+) mutation. Phase IB data from a trial that used cisplatin, gemcitabine, and veliparib treatment demonstrated a high response rate (RR), disease control rate (DCR), and overall survival (OS) in this population. We designed an open-label, randomized, multicenter, two-arm phase II trial to investigate cisplatin and gemcitabine with or without veliparib in gBRCA/PALB2+ PDAC.

PATIENTS AND METHODS

Eligible patients had untreated gBRCA/PALB2+ PDAC with measurable stage III to IV disease and Eastern Cooperative Oncology Group performance status of 0 to 1. Treatment for patients in arm A consisted of cisplatin 25 mg/m2 and gemcitabine 600 mg/m2 intravenously on days 3 and 10; treatment for patients in arm B was the same as that for patients in arm A, and arm A also received veliparib 80 mg orally twice per day on days 1 to 12 cycled every 3 weeks. The primary end point was RRs of arm A and arm B evaluated separately using a Simon two-stage design. Secondary end points were progression-free survival, DCR, OS, safety, and correlative analyses.

RESULTS

Fifty patients were evaluated by modified intention-to-treat analysis. The RR for arm A was 74.1% and 65.2% for arm B (P = .55); both arms exceeded the prespecified activity threshold. DCR was 100% for arm A and 78.3% for arm B (P = .02). Median progression-free survival was 10.1 months for arm A (95% CI, 6.7 to 11.5 months) and 9.7 months for arm B (95% CI, 4.2 to 13.6 months; P = .73). Median OS for arm A was 15.5 months (95% CI, 12.2 to 24.3 months) and 16.4 months for arm B (95% CI, 11.7 to 23.4 months; P = .6). Two-year OS rate for the entire cohort was 30.6% (95% CI, 17.8% to 44.4%), and 3-year OS rate was 17.8% (95% CI, 8.1% to 30.7%). Grade 3 to 4 hematologic toxicities for arm A versus arm B were 13 (48%) versus seven (30%) for neutropenia, 15 (55%) versus two (9%) for thrombocytopenia, and 14 (52%) versus eight (35%) for anemia.

CONCLUSION

Cisplatin and gemcitabine is an effective regimen in advanced gBRCA/PALB2+ PDAC. Concurrent veliparib did not improve RR. These data establish cisplatin and gemcitabine as a standard approach in gBRCA/PALB2+ PDAC.

Randomised phase II trial of gemcitabine and nab-paclitaxel with necuparanib or placebo in untreated metastatic pancreas ductal adenocarcinoma

BACKGROUND

Necuparanib, a rationally engineered low-molecular-weight heparin, combined with gemcitabine/nab-paclitaxel showed an encouraging safety and oncologic signal in a phase Ib trial. This randomised multicentre phase II trial evaluates the addition of necuparanib or placebo to gemcitabine/nab-paclitaxel in untreated metastatic pancreatic ductal adenocarcinoma (PDAC).

PATIENTS AND METHODS

Eligibility included 18 years, histologically or cytologically confirmed metastatic PDAC, measurable disease and Eastern Co-Operative Oncology Group performance status of 0-1. Patients were randomly assigned to necuparanib (5 mg/kg subcutaneous injection once daily) or placebo (subcutaneous injection once daily) and gemcitabine/nab-paclitaxel on days 1, 8 and 15 of 28-day cycles. The primary end-point was median overall survival (OS), and secondary end-points included median progression-free survival, response rates and safety.

RESULTS

One-hundred ten patients were randomised, 62 to necuparanib arm and 58 to placebo arm. The futility boundary was crossed at a planned interim analysis, and the study was terminated by the Data Safety Monitoring Board. The median OS was 10.71 months (95% confidence interval [CI]: 7.95-11.96) for necuparanib arm and 9.99 months (95% CI: 7.85-12.85) for placebo arm (hazard ratio: 1.12, 95% CI: 0.66-1.89, P-value: 0.671). The necuparanib arm had a higher incidence of haematologic toxicity relative to placebo patients (83% and 70%).

CONCLUSION

The addition of necuparanib to standard of care treatment for advanced PDAC did not improve OS. Safety was acceptable. No further development of necuparanib is planned although targeting the coagulation cascade pathway remains relevant in PDAC. NCT01621243.

Comparing the intra-tumoral distribution of Gemcitabine, 5-Fluorouracil, and Capecitabine in a murine model of pancreatic ductal adenocarcinoma

PURPOSE

To develop a technique to compare the intra-tumoral distribution of the drug gemcitabine, its surrogate [18F]-fluoroarabinocytosine ([18F]-FAC) and related chemotherapeutics 5-FU and capecitabine in a pre-clinical model of pancreatic ductal adenocarcinoma (PDAC).

EXPERIMENTAL DESIGN

Using a KPC-organoid derived model of PDAC, we obtained autoradiographic images of the tumor distribution of, [14C]-gemcitabine, [14C]-5-FU, [3H]-capecitabine. These were compared indirectly by co-administering [18F]-FAC, a close analog of gemcitabine with a proven equivalent intra-tumor distribution. The short half-life of 18F allows for clean separation of 3H/14C labeled drugs in specimens by dual isotope digital autoradiography. Autoradiographic images of [14C]-gemcitabine, [3H]-capecitabine and [14C]-5-FU were each correlated to [18F]-FAC on a pixel-by-pixel basis. The tumor drug penetration was compared using cumulative histograms.

RESULTS

Gemcitabine distribution correlated strongly with FAC as expected. 5-FU also gave a similar microdistribution to that of FAC, whereas no correlation was found between capecitabine or its metabolic products and FAC distribution. Accumulation of Gemcitabine and 5-FU was lower in hypoxic regions of the tumor, whereas no such correlation was observed for capecitabine and its metabolites.

CONCLUSIONS

Gemcitabine and 5-FU target the same regions of the tumor, leaving hypoxic cells untreated. Capecitabine metabolites penetrate further into the tumor but it is yet to be determined whether these metabolites are the active form of the drug.

The glycan CA19-9 promotes pancreatitis and pancreatic cancer in mice

Glycosylation alterations are indicative of tissue inflammation and neoplasia, but whether these alterations contribute to disease pathogenesis is largely unknown. To study the role of glycan changes in pancreatic disease, we inducibly expressed human fucosyltransferase 3 and β1,3-galactosyltransferase 5 in mice, reconstituting the glycan sialyl-Lewis^a, also known as carbohydrate antigen 19-9 (CA19-9). Notably, CA19-9 expression in mice resulted in rapid and severe pancreatitis with hyperactivation of epidermal growth factor receptor (EGFR) signaling. Mechanistically, CA19-9 modification of the matricellular protein fibulin-3 increased its interaction with EGFR, and blockade of fibulin-3, EGFR ligands, or CA19-9 prevented EGFR hyperactivation in organoids. CA19-9-mediated pancreatitis was reversible and could be suppressed with CA19-9 antibodies. CA19-9 also cooperated with the Kras^G12D oncogene to produce aggressive pancreatic cancer. These findings implicate CA19-9 in the etiology of pancreatitis and pancreatic cancer and nominate CA19-9 as a therapeutic target.

Young-onset pancreas cancer (PC) in patients less than or equal to 50 years old at Memorial Sloan Kettering (MSK): Descriptors, genomics, and outcomes

774

Background: For individuals ≤ 50 years old, cancer incidence is increasing, particularly gastrointestinal and obesity related cancers (Sung, Lancet Public Health 2019). Limited details are known about young onset PC. Herein, we report the epidemiologic, pathologic, and molecular characteristics of PC in patients (pts) ≤ 50 years. Methods: MSK institutional database was queried for medical and treatment history, genomics, and outcomes in pts ≤ 50 years old diagnosed with PC between January 2008 and July 2018. Neuroendocrine cancers were excluded. Overall survival (OS) from date of PC diagnosis was estimated using Kaplan-Meier methods. Results: N = 450 pts ≤ 50 years old with a diagnosis of PC were identified. Ninety-six percent had adenocarcinoma, and 4% had acinar cell carcinoma/other histologies. Table summarizes demographics. Median OS was 16 months in the entire cohort and 11.3 months in stage IV disease. For N = 236 pts diagnosed after 2014, 119 (50%) underwent successful somatic testing with at least one alteration identified, and 21/119 tumors were RAS wild-type with identification of several actionable alterations (NRG1 fusions (n=2), NTRK fusions (n=2), IDH1 R132C (n=1), and microsatellite unstable tumors (n=1) ). N = 114 pts had germline testing (routine after 2015), and 33/114 (29%) had pathologic germline alterations, including BRCA1/2 (n=18), CHEK2 (n=3), PALB2 (n=3), ATM (n=2), MLH1 (n=1), and MSH3 (n=1). Conclusions: Pathogenic germline alterations are present in a substantial percentage of pts with young onset PC, and actionable somatic alterations were seen frequently in the subgroup of young onset PC RAS-wild type tumors. These observations underpin the need for germline and somatic profiling in PC. [Table: see text]

Impact of prior irinotecan exposure on outcomes of metastatic pancreatic cancer (mPC) patients

667

Background: Published data suggests prior exposure to irinotecan infers a lower likelihood of benefit to liposomal irinotecan. This analysis seeks to expand this hypothesis by evaluating U.S. patterns of care to understand how prior irinotecan therapy impacts outcomes in mPC. Methods: Using the Flatiron Health database, data were extracted and analyzed for treated mPC patients (pts) in the 2L+ setting between Jan 1, 2014 and Jun 30,2019. Therapies of interest included: gemcitabine/ nab-paclitaxel (GnP), FOLFOX, FOLFIRI, FOLFIRINOX (FFX), and liposomal irinotecan/5-FU/LV (nal-IRI). The reference date for each treatment group was the date of treatment initiation. Prior irinotecan was defined as any irinotecan given in a prior regimen in mPC diagnosis. Cox proportional hazard (PH) methods were used to calculate mortality hazard ratios (HRs). HRs were adjusted to account for demographics and relevant covariates. Pts with prior exposure to irinotecan were used as the reference population for the Cox PH model (an HR < 1 represents worse survival for exposed pts relative to the unexposed). Results: N = 1,978 were included in this analysis. The median age at treatment initiation, and the proportion of pts previously treated with irinotecan are reported in table. Crude mortality was: GnP pts, HR 0.93 [95% CI: 0.77 – 1.11, adjusted HR, 0.94, 0.76 – 1.15]; nal-IRI pts, HR 0.81 [0.64 – 1.02, adjusted HR: 0.89, 0.67 – 1.19]; HR for FOLFOX was 0.55 [0.38 – 0.78, adjusted HR: 0.51, 0.33 – 0.79]. HRs are not reported for FFX and FOLFIRI due to the small numbers with prior irinotecan exposure. Conclusions: In mPC, prior irinotecan treatment may not preclude benefit from later treatment with nal-IRI or GnP as can be seen from the adjusted and unadjusted HRs. These findings are hypothesis-generating and need to be considered in the context of wide CI’s, retrospective nature and the limitations of such data. Further study is required to understand the less-favorable signal observed with FOLFOX and prior irinotecan.[Table: see text]

Pharmacogenomic blood-based assay to predict chemotherapy response and survival in pancreatic cancer

738

Background: Pancreatic adenocarcinoma (PDAC) is for most patients a refractory disease. Modern cytotoxic chemotherapeutics (C) are not yet optimal for inducing responses and extending life. We are developing a blood-based pharmacogenomic (PGx) assay profiling circulating tumor and invasive cells (CTICs) to predict sensitivity and resistance to C. Methods: The PGx assay was studied in two cohorts of patients (pts) presenting for frontline C therapy of metastatic PDAC. Cohort 1 is from an ongoing prospective study (planned n=80); pts are enrolled prior to receiving either FOLFIRINOX or gemcitabine (Gem)/nab-paclitaxel (Nab-P). Cohort 2 (n=50) consists of pts enrolled prior to receiving bespoke combinations of C agents informed by the assay. 6 mL of peripheral blood was collected from pts at baseline and while on C therapy. CTICs were isolated by previously described collagen invasion assay, total RNA was extracted and gene-expression analysis was performed. PGx models for seven C agents used in PDAC were applied, and correlated to treatment received. Pts were classified as sensitive if C received were predicted to be effective and resistant if not. Objective endpoints were PFS and OS. Results: Cohort 1 patients who received sensitive first-line C combinations experienced significantly longer time to progression (TTP) v resistant (Table). In Cohort 2, the PGx assay was predictive of TTP and OS when used across multiple lines of therapy, with a two-year survival of 38%. Greater OS was observed in Cohort 2 pts receiving heterogenous C regimens more highly correlated to those predicted by the PGx assay. Conclusions: The PGx assay has promising predictive performance in both standard and personalized C regimens. A prospective, directed trial comparing these approaches is warranted. Clinical trial information: NCT03033927. [Table: see text]

Pancreatic ductal adenocarcinoma (PDAC), BRCA: Detailed analysis and outcomes of cohort from Memorial Sloan Kettering Cancer Center (MSK)

708

Background: Given encouraging responses of platinum agents and poly-ADP ribose polymerase inhibitors (PARPi) in BRCA mutated (mut) PDAC, we sought to identify patients (pts) with BRCA mut PDAC treated at MSKCC and to evaluate outcome. Methods: Institutional database at MSK with IRB approval was queried for PDAC germline (g) or somatic (s) BRCA1/2 mut. Genomic profiling, clinicopathologic characteristics and outcomes were collected. Overall survival (OS) from diagnosis was estimated using Kaplan-Meier method. Results: n = 126 with BRCA1/2 mut PDAC were identified between 1/2011-12/2018. n = 77 (61%) male and median age of 62 (range 24-85) at diagnosis. n = 78 (62%) had g BRCA mut (n = 21 BRCA1; n = 57 BRCA2). n = 54 (43%) had a family history of BRCA-related malignancies; 35pts (28%) with a personal history of other BRCA-associated malignancy. n = 66 (52%) AJCC stage IV; of these 43pts (65%) received platinum-based therapy with a partial response (PR) in 35pts (81%); median duration 7 months (m) (range 0.5-39m). n = 40 (32%) received ≥ 4 lines of therapy (range 1-6 lines). n = 44 (35%) received PARPi and 11% (n = 14) received immunotherapy. Median OS for the entire cohort 32.1 m (95% CI 23.9, 42.6). Median OS for stage I-II 49.9m (95% CI 38.5,-); stage III 43m (95% CI 33.9,-) and stage IV 19.1m (95% CI 19.1 16.1,25.8). We did not observe a statistically significant difference in OS between BRCA1 vs BRCA2 pts. Conclusions: BRCA mut PDAC constitutes a small but likely distinct biologic subgroup. Improved OS was notable relative to historical data, possibly due to the integration of platinum and PARPi therapy and possibly due to contribution from disease biology. [Table: see text]

A randomized, multicenter, phase II trial of gemcitabine (G), cisplatin (C) +/- veliparib (V) in patients with pancreas adenocarcinoma (PDAC) and a known germline (g)BRCA/ PALB2 mutation

639

Background: gBRCA 1,2 mutations occur in 5-8% PDAC. Platinum and poly-ADP ribose polymerase inhibitors (PARPi) effective in BRCA-mut cancers. Phase I GC + V high RR 78%; combination may delay resistance in PDAC (O’Reilly, Cancer, 2018). Herein, we evaluate GC +/- V in a multi-national, randomized phase II trial. Methods: Eligibility: Untreated germline (g)BRCA, PALB2 mut PDAC; measurable stage III/IV; ECOG 0-1. Randomized 1:1 Arm A or B. Treatment: Arm A: G 600 mg/m2 IV, C 25 mg/m2 IV, d3 and 10, V 80 mg PO BID day 1-12, all q 3 weeks or Arm B: GC only. Primary endpoint: RECIST 1.1 response rate (RR). Simon 2-stage per arm: null hypothesis 10% vs promising 28%; type I, II error 10%. Secondary endpoints: progression-free survival (PFS), OS (m), disease control rate (CR+PR+SD), safety and correlative analyses. PFS, OS compared between arms using log-rank test and RR, DCR using Fisher’s exact test between arms. Results: N = 52 enrolled 01/14- 11/18. N = 2 withdrew Arm B. N = 50 for ITT. Male = 22 (44%), Female = 28. Median age = 64 years (range 37-82). BRCA1 N = 12, BRCA2 N = 35, PALB2 N = 3. Stage III N = 8; Stage IV N = 42. Hematologic Toxicity: Arm A vs Arm B: Gd 3-4 neutropenia 13 (48%) vs 7 (30%); Gd 3-4 platelets 15 (55%) vs 2 (9%); Gd 3-4 anemia 14 (52%) vs 8 (35%). Non-hematologic toxicity similar Arm A vs B. Exploratory analyses (combined Arms): Med OS if > 4 m platinum → PARPi: 23 m (95%CI 6.5- 53.9). Med OS by BRCA: BRCA1: 14 m (8.1- 18.5); BRCA2: 20.2 m (12.3- 24.4). Med OS by ECOG: ECOG 0: 23 m (13.8- 24.5); ECOG 1: 14.3 (8.1 vs 16.4). Two-year OS rate for entire cohort: 30.6% and 3-year OS: 17.8%. Conclusions: GC +/- V very active in gBRCA/PALB2 mut PDAC with high RR, PFS, OS with both A, B significantly exceeding threshold RR. Improved DCR arm A vs B, but with greater heme toxicity A vs B. Study confirms GC as reference treatment in gBRCA/PALB2 with durable survival in subset. Funding: National Cancer Institute, CTEP, Lustgarten Foundation, AbbVie. Clinical trial information: NCT01585805 . [Table: see text]

Identification of Resistance Pathways Specific to Malignancy Using Organoid Models of Pancreatic Cancer

PURPOSE

KRAS is mutated in the majority of pancreatic ductal adenocarcinoma. MAPK and PI3K-AKT are primary KRAS effector pathways, but combined MAPK and PI3K inhibition has not been demonstrated to be clinically effective to date. We explore the resistance mechanisms uniquely employed by malignant cells.

EXPERIMENTAL DESIGN

We evaluated the expression and activation of receptor tyrosine kinases in response to combined MEK and AKT inhibition in KPC mice and pancreatic ductal organoids. In addition, we sought to determine the therapeutic efficacy of targeting resistance pathways induced by MEK and AKT inhibition in order to identify malignant-specific vulnerabilities.

RESULTS

Combined MEK and AKT inhibition modestly extended the survival of KPC mice and increased Egfr and ErbB2 phosphorylation levels. Tumor organoids, but not their normal counterparts, exhibited elevated phosphorylation of ERBB2 and ERBB3 after MEK and AKT blockade. A pan-ERBB inhibitor synergized with MEK and AKT blockade in human PDA organoids, whereas this was not observed for the EGFR inhibitor erlotinib. Combined MEK and ERBB inhibitor treatment of human organoid orthotopic xenografts was sufficient to cause tumor regression in short-term intervention studies.

CONCLUSIONS

Analyses of normal and tumor pancreatic organoids revealed the importance of ERBB activation during MEK and AKT blockade primarily in the malignant cultures. The lack of ERBB hyperactivation in normal organoids suggests a larger therapeutic index. In our models, pan-ERBB inhibition was synergistic with dual inhibition of MEK and AKT, and the combination of a pan-ERBB inhibitor with MEK antagonists showed the highest activity both in vitro and in vivo.

A randomized phase II trial of nab-paclitaxel and gemcitabine with tarextumab or placebo in patients with untreated metastatic pancreatic cancer

Purpose

Notch signaling dysregulation is implicated in the development of pancreatic adenocarcinoma (PDAC). Tarextumab is a fully human IgG2 antibody that inhibits Notch2/3 receptors.

Patients and Methods

Aphase 2, randomized, placebo‐controlled, multicenter trial evaluated the activity of tarextumab in combination with nab‐paclitaxel and gemcitabine in patients with metastatic PDAC. Patients were stratified based on ECOG performance score and Ca 19‐9 level and randomized 1:1 to nab‐paclitaxel, gemcitabine with either tarextumab or placebo. Based on preclinical and phase Ib results suggesting a positive correlation between Notch3 gene expression and tarextumab anti‐tumor activity, patients were also divided into subgroups of low, intermediate, and high Notch3 gene expression. Primary endpoint was overall survival (OS) in all and in patients with the three Notch3 gene expression subgroups (≥25th, ≥50% and ≥75% percentiles); secondary end points included progression‐free survival (PFS), 12‐month OS, overall response rate (ORR), and safety and biomarker investigation.

Results

Median OS was 6.4 months in the tarextumab group vs 7.9 months in the placebo group (HR = 1.34 [95% CI = 0.95, 1.89], P = .0985). No difference observed in OS in the Notch3 gene expression subgroups. PFS in the tarextumab‐treated group (3.7 months) was significantly shorter compared with the placebo group (5.5 months) (hazard ratio was 1.43 [95% CI = 1.01, 2.01]; P = .04). Grade 3 diarrhea and thrombocytopenia were more common in the tarextumab group.

Conclusions

The addition of tarextumab to nab‐paclitaxel and gemcitabine did not improve OS, PFS, or ORR in first‐line metastatic PDAC, and PFS was specifically statistically worse in the tarextumab‐treated patients.

Clinical trial registry no

NCT01647828.

Cross-Species Single-Cell Analysis of Pancreatic Ductal Adenocarcinoma Reveals Antigen-Presenting Cancer-Associated Fibroblasts

Cancer-associated fibroblasts (CAF) are major players in the progression and drug resistance of pancreatic ductal adenocarcinoma (PDAC). CAFs constitute a diverse cell population consisting of several recently described subtypes, although the extent of CAF heterogeneity has remained undefined. Here we use single-cell RNA sequencing to thoroughly characterize the neoplastic and tumor microenvironment content of human and mouse PDAC tumors. We corroborate the presence of myofibroblastic CAFs and inflammatory CAFs and define their unique gene signatures in vivo. Moreover, we describe a new population of CAFs that express MHC class II and CD74, but do not express classic costimulatory molecules. We term this cell population "antigen-presenting CAFs" and find that they activate CD4⁺ T cells in an antigen-specific fashion in a model system, confirming their putative immune-modulatory capacity. Our cross-species analysis paves the way for investigating distinct functions of CAF subtypes in PDAC immunity and progression. SIGNIFICANCE: Appreciating the full spectrum of fibroblast heterogeneity in pancreatic ductal adenocarcinoma is crucial to developing therapies that specifically target tumor-promoting CAFs. This work identifies MHC class II-expressing CAFs with a capacity to present antigens to CD4⁺ T cells, and potentially to modulate the immune response in pancreatic tumors.See related commentary by Belle and DeNardo, p. 1001.This article is highlighted in the In This Issue feature, p. 983.

Association of pancreatic cancer stem cells with tumor stroma type

e15771

Background: Pancreatic ductal adenocarcinoma (PDA) is a heterogeneous disease with distinct stroma features. Cancer stem cells (CSC) in PDA may express CD44 (C) +/- Epithelial Specific Antigen (E). We investigated the relationship of CSC markers with tumor stroma and clinical outcomes in PDA patients (pts) who had surgical resection. Methods: Pts who underwent PDA resection with IRB #00-032/#06-107 consent between 01/2012-06/2014 at Memorial Sloan Kettering were identified. C and E immunohistochemical (IHC) expression scored as follow: 0, none; 1, 1%–10%; 2, 11%–50%; 3, 51%–80%; 4, 81%–100%. Staining intensity was scored as 0, none; 1, weak; 2, moderate; 3, strong. The total scores (0-12) were averaged and was considered positive when average score > median. Stroma was classified as loose, moderate and dense based on fibroblast content using H&E stain. Overall survival (OS) and relapse-free survival (RFS) were estimated using the Kaplan-Meier and compared by log-rank test; association between CSC markers and stroma type was assessed by Fisher`s exact test. Results: N = 93 PDA pts identified. PDA with C(+) E(-) had significantly higher loose stroma and PDA with C(-) E(+) and C(-) E(-) had more moderate and dense stroma (p = 0.0033). The number of PDA pts with dense, moderate, and loose stroma was: 11, 31, and 51 respectively. No local recurrence in pts with dense stroma observed and 8/11 had either lung or liver recurrence. Six of 31pts with loose stroma had a local recurrence and 13/31 pts had either liver or lung recurrence. No statistically significant difference in OS and RFS were observed among subgroups (P = 0.089). Median time from relapse to death was: 2, 11.5, 10,5 and months 7 in C+/E-, C-/E+, C+/E+, and C-/E- groups respectively. Conclusions: PDA CSCs appears to have an association with PDA stroma type. We also observed different recurrence patterns among stroma subgroups. Respecting small sample size, these data indicate CSCs may have an important role in stroma differentiation in PDA. CSC markers do not predict OS and RFS, however, resected PDA with C(+) E(-) may have more aggressive behavior following recurrence. [Table: see text]