Citations

8579 Background: The ERIVANCE BCC study is the pivotal trial of vismodegib (GDC-0449), a first-in-class small-molecule inhibitor of Hedgehog signaling, for treatment of locally advanced (laBCC) and metastatic BCC (mBCC), for whom there are no other effective therapy options. The study met the primary endpoint of overall response rate by independent review (Sekulic, Melanoma Res 2011). Here we report a 6-mo update of investigator-assessed (I-A) efficacy and safety endpoints as of May 26, 2011. Methods: This multicenter, international, nonrandomized 2-cohort study enrolled patients (pts) with laBCC (deemed inoperable or for whom surgery would be significantly disfiguring), and mBCC pts with RECIST-measurable disease. Pts received 150 mg oral vismodegib daily. Results: 104 pts (71 laBCC/33 mBCC) enrolled at 31 sites in the US, Europe, and Australia. I-A efficacy endpoints are shown in the table. One-year survival rate was 77.3% (95% CI 62.48–92.09%) for mBCC and 93.1% (95% CI 86.49–99.63%) for laBCC. Adverse events (AEs) in >30% of pts were muscle spasms, alopecia, dysgeusia, weight decrease, fatigue, nausea, and amenorrhea (33.3%; 2/6 pts). Serious AEs were reported in 32 pts (31%). No additional fatal AEs were reported since the prior data cut (n=7, 7%; none considered related to vismodegib). Conclusions: This 6-mo update of I-A efficacy and safety endpoints from the ERIVANCE BCC study supports the significant clinical benefit of vismodegib in both laBCC and mBCC reported at the primary analysis. Median DOR and PFS increased numerically with follow-up. The AE profile was consistent with the prior data cut. These results further support the efficacy of vismodegib for treatment of advanced BCC. [Table: see text]

8095 Background: Multiple myeloma (MM) remains incurable and invariably relapses after initial therapy. There is no uniform approach to management of relapsed MM and is dictated by type of initial therapy and the response seen, and availability of new drugs. The outcomes associated with current approaches have not been systematically examined. Methods: We enrolled 383 patients (pts) with myeloma who had a documented relapse between Jan 2007 and June 2010, including 220 from Europe, 106 from Asia, and 31 from South America and 26 from North America. Time Zero (T0) was defined as date of treatment after first relapse. Results: Across the study, 61% were male and 49% were over 65 years at T0. ISS stage distribution at diagnosis included 26, 40 and 33% of patients in stages 1, 2 and 3, respectively. Among regimens used at first relapse; bortezomib (Btz) containing regimens were most common (54%), followed by lenalidomide (Len, 25%) and cyclophosphamide (21%). The overall response rate (>=PR) to first therapy after relapse was 58% including 14% with a CR. There was a progressive decrease in the response rates with successive regimen; 45%, 30% and 15% for regimens 2, 3 and 4 respectively. Len use was considerably lower in the Asian cohort, while Btz use was comparable across the regions. The median PFS from T0 was 13 mos and OS was 35 mos, for the entire cohort. The PFS to first salvage regimen was similar across the regions, while OS was shorter for the Asian and South American cohorts. In a univariate analysis, ISS stage 3, presence of cytogenetic abnormalities, history of plasma cell leukemia or extramedullary disease (EMD), bone marrow PC% > 33% and presence of renal insufficiency were all associated with a shorter PFS as well as shorter OS (P<=0.01). In a multivariate model, ISS stage 3 and presence of EMD were most associated with short OS. Conclusions: Median PFS for current second line regimens, typically containing Btz or Len appear to be 1 yr with an OS from first relapse of about 3 yrs. The OS from first relapse is nearly double that seen in a cohort of patients in first relapse prior to introduction of new drugs. Clear-cut regional differences can be seen in terms of patterns of drug use and likely reflect drug availability and healthcare costs.

Abstract Purpose: Clear cell ovarian carcinoma (CCOC) is an aggressive disease that often demonstrates resistance to standard chemotherapies. Approximately 25% of patients with CCOC show a strong APOBEC mutation signature. Here, we determine which APOBEC3 enzymes are expressed in CCOC, establish clinical correlates, and identify a new biomarker for detection and intervention. Experimental Designs: APOBEC3 expression was analyzed by IHC and qRT-PCR in a pilot set of CCOC specimens (n = 9 tumors). The IHC analysis of APOBEC3B was extended to a larger cohort to identify clinical correlates (n = 48). Dose-response experiments with platinum-based drugs in CCOC cell lines and carboplatin treatment of patient-derived xenografts (PDXs) were done to address mechanistic linkages. Results: One DNA deaminase, APOBEC3B, is overexpressed in a formidable subset of CCOC tumors and is low or absent in normal ovarian and fallopian tube epithelial tissues. High APOBEC3B expression associates with improved progression-free survival (P = 0.026) and moderately with overall survival (P = 0.057). Cell-based studies link APOBEC3B activity and subsequent uracil processing to sensitivity to cisplatin and carboplatin. PDX studies extend this mechanistic relationship to CCOC tissues. Conclusions: These studies demonstrate that APOBEC3B is overexpressed in a subset of CCOC and, contrary to initial expectations, associated with improved (not worse) clinical outcomes. A likely molecular explanation is that APOBEC3B-induced DNA damage sensitizes cells to additional genotoxic stress by cisplatin. Thus, APOBEC3B is a molecular determinant and a candidate predictive biomarker of the therapeutic response to platinum-based chemotherapy. These findings may have broader translational relevance, as APOBEC3B is overexpressed in many different cancer types.

TPS276 Background: Immune checkpoint inhibitors have revolutionized the treatment of a number of cancers. In colorectal cancers, their efficacy is limited to mismatch repair deficient or microsatellite stability-high (dMMR/MSI-High) tumors only. These constitute only 4-5% of all metastatic colorectal cancers (mCRC). Novel approaches are needed to make immunotherapy a viable option for mismatch repair proficient or microsatellite stable (pMMR/MSS) tumors. Increasing exposure of neo-antigens to the immune system could be one potential strategy to enhance the response of immunotherapy. Yttrium 90-radioembolization (Y90-RE) in combination with immunotherapy may work synergistically to enhance efficacy of each other. Additionally, radiation can potentially make the tumor microenvironment conducive to effector T-cell recruitment and function. Therefore, we hypothesize and propose the clinical trial of combining immunotherapy with Y90-RE as a feasible and safe strategy that will improve outcomes in patients with mCRC with liver-predominant metastases. Methods: This clinical trial will be conducted as a single-center, open-label, Phase I/II trial to evaluate initially the feasibility and safety of Y90-RE in combination with a fixed dose of immunotherapy (durvalumab) in subjects with liver-predominant, mCRC (Table). It will be offered in the refractory setting. The trial will be performed in 18 subjects with mCRC with liver metastasis and the safety of immunotherapy (durvalumab) with Y90-RE will be investigated in an accelerated titration design. This would allow a maximum tolerated dose with the minimum number of subjects. Correlative studies pertaining to serial circulating tumor DNA (ctDNA - liquid biopsies) testing as well as immune-panel based profiling will be performed alongside pre- and post-biopsies to study changes in the tumor microenvironment. Clinical trial information: NCT04108481. [Table: see text]

763 Background: Non-invasive biomarkers with high sensitivity and specificity would be of great value for patients with Pancreatic Ductal Adenocarcinoma (PDAC). This would aid in early detection and serve other purposes that 'liquid biopsies' are being explored in. Besides circulating tumor DNA (ctDNA) and methylation markers, glycosylation markers hold great potential promise. We developed a novel workflow using high-resolution quantification of site-specific protein glycosylation by liquid chromatography and tandem mass spectrometry to evaluate the clinical utility of glycoprotemics signature for patients with PDAC. Methods: Serum samples from newly diagnosed PDAC patients and controls were obtained from a commercial biobank (Indivumed, Hamburg, Germany), and a panel of 504 glycan motifs, representing 73 previously reported proteomic markers, was determined. Age-adjusted generalized linear regression models were used to evaluate the differential abundance of each marker, and stepwise variable selection was used for model construction. Results: We analyzed 45 PDAC and 136 control samples. PDAC patients (60% male) had a mean age of 67 (±11) years. with 4.4%, 71.1%, 4.4%, and 20% at stage 1, 2, 3,4, respectively. Controls were women with benign histology after pelvic mass surgery; with a mean age of 61 (±11) years. Twenty-six glycoproteomic markers showed statistically highly significant differential abundance among cases and controls (p<1e-4 each) and were highly reproducible(Pearson’s r > 0.85), which were glycoforms in proteins that have previously been found to be associated with PDAC. Fourteen of these markers displayed >0.8 area under the curve of the receiver operating characteristic (AUC). Multivariate logistic regression modeling with backward selection yielded a classification model with an AUC of 0.94 (95% CI: 0.89-0.99), sensitivity of 91% (95% CI: 75-97%) and specificity of 86% (95% CI: 81-92%). Conclusions: Circulating glycoproteomic biomarkers may be useful in the early detection and clinical management of PDAC patients; offering a new platform to explore and validate.

Background Poly(adenosine diphosphate ribose) polymerase (PARP) inhibitors exhibit promising activity against ovarian cancers, but their efficacy can be limited by acquired drug resistance. This study explores the role of autophagy in regulating the sensitivity of ovarian cancer cells to PARP inhibitors. Methods Induction of autophagy was detected by punctate LC3 fluorescence staining, LC3I to LC3II conversion on Western blot analysis, and electron microscopy. Enhanced growth inhibition and apoptosis were observed when PARP inhibitors were used with hydroxychloroquine, chloroquine (CQ), or LYS05 to block the hydrolysis of proteins and lipids in autophagosomes or with small interfering RNA against ATG5 or ATG7 to prevent the formation of autophagosomes. The preclinical efficacy of the combination of CQ and olaparib was evaluated with a patient‐derived xenograft (PDX) and the OVCAR8 human ovarian cancer cell line. Results Four PARP inhibitors (olaparib, niraparib, rucaparib, and talazoparib) induced autophagy in a panel of ovarian cancer cells. Inhibition of autophagy with CQ enhanced the sensitivity of ovarian cancer cells to PARP inhibitors. In vivo, olaparib and CQ produced additive growth inhibition in OVCAR8 xenografts and a PDX. Olaparib inhibited PARP activity, and this led to increased reactive oxygen species (ROS) and an accumulation of γ‐H2AX. Inhibition of autophagy also increased ROS and γ‐H2AX and enhanced the effect of olaparib on both entities. Treatment with olaparib increased phosphorylation of ATM and PTEN while decreasing the phosphorylation of AKT and mTOR and inducing autophagy. Conclusions PARP inhibitor–induced autophagy provides an adaptive mechanism of resistance to PARP inhibitors in cancer cells with wild‐type BRCA, and a combination of PARP inhibitors with CQ or other autophagy inhibitors could improve outcomes for patients with ovarian cancer.

Abstract BRCA1 plays a key role in homologous recombination (HR) DNA repair. Accordingly, changes that downregulate BRCA1, including BRCA1 mutations and reduced BRCA1 transcription, due to promoter hypermethylation or loss of the BRCA1 transcriptional regulator CDK12, disrupt HR in multiple cancers. In addition, BRCA1 has also been implicated in the regulation of metabolism. Here, we show that reducing BRCA1 expression, either by CDK12 or BRCA1 depletion, led to metabolic reprogramming of ovarian cancer cells, causing decreased mitochondrial respiration and reduced ATP levels. BRCA1 depletion drove this reprogramming by upregulating nicotinamide N-methyltransferase (NNMT). Notably, the metabolic alterations caused by BRCA1 depletion and NNMT upregulation sensitized ovarian cancer cells to agents that inhibit mitochondrial metabolism (VLX600 and tigecycline) and to agents that inhibit glucose import (WZB117). These observations suggest that inhibition of energy metabolism may be a potential strategy to selectively target BRCA1-deficient high-grade serous ovarian cancer, which is characterized by frequent BRCA1 loss and NNMT overexpression. Significance: Loss of BRCA1 reprograms metabolism, creating a therapeutically targetable vulnerability in ovarian cancer.

Abstract Introduction: Determining the optimal post-remission management for elderly patients with acute myeloid leukemia (AML) remains a challenge. AML is primarily a disease of the elderly with >60% of newly diagnosed patients aged 60 years and older. For younger AML patients, post-remission therapy in the form of high-dose cytarabine (HIDAC) consolidation or allogeneic hematopoietic stem cell transplant (HSCT) is critical in maintaining durable disease control and improving survival. However, post-remission HIDAC in elderly AML patients is associated with higher rates of neurotoxicity and decreased survival benefit compared to younger patients. The optimal post-remission therapy for elderly AML patients remains undefined. The objective of this study is to determine the outcomes of using varying doses (0.25-3 g/m2) of cytarabine as post-remission consolidation therapy in an elderly AML population. Methods: We conducted a single-center retrospective analysis of AML patients aged 60 years and older treated with cytarabine as consolidation therapy at UPMC Hillman Cancer Center between January 1, 2005 and December 31, 2014. Patients were excluded if they were not in complete morphologic remission prior to proceeding with cytarabine consolidation or if they proceeded directly to HSCT after consolidation therapy. Relapse-free survival (RFS) was measured from the time of post-induction bone marrow biopsy confirming remission to the date of relapse or death. Overall survival (OS) was defined as the duration from diagnostic bone marrow biopsy confirming AML diagnosis to the date of death. Kaplan-Meier analysis was used to estimate the survival distributions and log-rank test was used to compare survival functions from groups. Multivariate analysis was performed using Cox proportional hazard regression to determine the relationship of RFS and OS to patient's age, cytogenetic risk group, AML type (de novo vs secondary AML), transplant status, cytarabine dosage and number of cycles. All data was analyzed using SAS v9.4 (SAS Institute, Cary, NC, USA). Results: Out of 156 identified patients, 121 were eligible for analysis. Median age at diagnosis was 66 years (range 59-78) with 77 (64%) male patients. Thirty-six patients (30%) had secondary AML. Cytogenetic abnormalities were favorable in 7 (6%), intermediate in 86 (71%), unfavorable in 24 (20%), and unknown in 4 (3%) patients. Cytarabine was administered at a mean dose of 1.44 g/m2 (range 0.25-3.0, SD 0.84) and a median number of cycles of 4 (range 1-4). One patient (0.8%) developed reversible grade 3 neurotoxicity during cycle 2 at a dose of 2 g/m2 with ataxia, dysmetria, and tremors. For all patients, the median RFS was 12.5 months (95% CI 9.7-15.6). Median RFS was significantly different among the cytogenetic risk groups (p=0.0008 via log-rank test): favorable-risk RFS had not been reached because most subjects were in remission and alive at time of analysis, intermediate-risk RFS 13.6 months (95% CI 11.0-17.3), unfavorable-risk RFS 8.3 months (95% CI 3.5-8.9). In this study population, the median OS was 20.5 months (95% CI 16.4-27.1). Median OS was significantly different among the cytogenetic risk groups (p=0.003 via log-rank test): favorable-risk OS 131.3 months (95% CI 12.9-upper limit not reached), intermediate-risk OS 25.1 months (95% CI 18.9-39.4), and unfavorable-risk OS 10.8 months (95% CI 10.4-15.8). Average cytarabine dose did not significantly correlate with RFS or OS in the model. Multivariate analysis revealed a 27% decreased rate of relapse (HR 0.73, 95% CI 0.58-0.92, p=0.008), and 24% decreased mortality rate (HR 0.76, 95% CI 0.59-0.96, p=0.024) with each additional cytarabine cycle given. Conclusions: Our study supports the use of cytarabine as a tolerable and effective option for post-remission therapy in elderly AML patients, particularly those with favorable-risk cytogenetics. Each additional cycle administered was associated with improved RFS and OS rates in this study population. Disclosures No relevant conflicts of interest to declare.

Abstract Neuroblastoma is an embryonal tumor arising in the peripheral sympathetic nervous system (PSNS), and often presents with widespread metastasis at diagnosis. We recently demonstrated that overexpression of LMO1 can synergize with MYCN to promote tumor metastasis in our zebrafish model system. Here, we identify a “metastasis suppressor” gene – growth arrest specific 7 (GAS7) – whose loss of function or reduced expression can promote dissemination and migration of neuroblastoma cells with MYCN overexpression, both in vitro and in vivo. GAS7 resides on chromosome 17p13.1, a region that is deleted in high-risk neuroblastomas with higher frequency in MYCN-amplified cases. Expression levels of GAS7 are also significantly downregulated in MYCN-amplified or otherwise MYCN-overexpressing human neuroblastoma cells, as well as MYCN-overexpressing zebrafish PSNS cells, suggesting an inverse relationship between the oncogenic activities of MYCN and GAS7downregulation. To determine whether loss of function or reduced expression of GAS7 could contribute to neuroblastoma pathogenesis in the context of MYCN overexpression, we developed a gas7 knockout zebrafish line using a transcription activator-like effector nucleases (TALEN) method. Loss of function of gas7 promoted hematogenous metastasis of MYCN-overexpressing tumor cells to tissues and organs that paralleled the common sites of metastasis in neuroblastoma patients. Further RNA-sequencing and qRT-PCR analyses showed that representative signature genes encoding proteins involved in tumor cell-cell or cell-extracellular matrix interactions were significantly downregulated in fish tumors with loss of function of gas7, consistent with our electron microscopic finding in the fish model showing a loss of contact among tumor cells in fish lacking functional gas7, suggesting that GAS7 may physically act as a metastasis suppressor. Thus, in high-risk neuroblastoma with MYCNamplification or overexpression, we propose that deletion or reduced expression of GAS7 cooperates with MYCN to promote neuroblastoma cell dissemination. Although the precise mechanism of this interaction remains unclear, we suggest that it relies, in part, on the downregulation of pivotal genes involved in tumor cell-cell or cell-extracellular matrix contacts. Citation Format: Zhiwei Dong, Gonzalo Lepez Garcia, Cheng Zhang, Erin N. Dankert, Jo Lynne Harenza, Xiaonan Hou, Hu Li, John M. Maris, Shizhen (Jane) Zhu. Loss of function of GAS7 promotes neuroblastoma metastasis in the context of MYCN overexpression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-127.

Abstract Poly (ADP) ribose polymerase inhibitors (PARPi) have shown promising activity against recurrent ovarian cancers, particularly in women with germ line mutations of BRCA1/2. The efficacy of PARP inhibitors can, however, be decreased by acquired drug resistance. Autophagy or “self-eating” is one mechanism implicated in cancer progression and therapy resistance. Autophagy is a catabolic mechanism that can degrade organelles and long-lived proteins to provide energy for cancer cells under nutrient poor conditions or in the presence of stress. The energy provided from autophagy is used to fuel the DNA repair process and metabolic needs in cancer cells. Autophagy can protect cancer cells from chemotherapy or can enhance the response to certain drugs. In this study, we have asked whether autophagy contributes to the resistance of ovarian cancer cells to PARPi. Our group has found that four PARP inhibitors (olaparib, niraparib, rucaparib and talazorapib) induce autophagy in 8 ovarian cancer cell lines, detected by LC3A to LC3B conversion on western blot analysis and punctate GFP-LC3 fluorescence. Transmission electron microscopy confirmed the increased autophagosome formation in olaparib treated cells. To test whether autophagy contributes to the resistance of OC cells to olaparib, we determined the impact of autophagy inhibition on the sensitivity of OC cell lines to olaparib by either using chloroquine, hydroxychloroquine or LYS05 to block hydrolysis of proteins and lipids in autophagosomes or using siRNA against ATG5 or ATG7 to prevent formation of autophagosome. Enhancement of PARPi activity was observed in 6 out 8 ovarian cancer cell lines. Moreover, a combination of olaparib and chloroquine proved more effective than either single agent in a xenograft model of the OVCAR8 ovarian cancer cell line and in a patient derived xenograft model. Mechanistically, olaparib decreased PARP activity leading to DNA damage and accumulation of γ-H2AX. Olaparib treatment increased reactive oxygen species (ROS) and phosphorylation of ATM, while decreasing the phosphorylation of AKT and mTOR. We also observed an increase in PTEN, a well-recognized negative regulator of AKT. Inhibition of PTEN decreases LC3 conversion, suggesting PTEN as an important regulator of olaparib-induced autophagy in ovarian cancer cells. Taken together, our data demonstrate for the first time that olaparib induces autophagy in ovarian cancer cells and provides an adaptive mechanism of resistance to PARPi. Olaparib-induced autophagy may depend upon activation of ATM and PTEN by ROS, downregulating pAKT/pmTOR signaling. Moreover we have identify unique combinations of therapy with PARPi and CQ or other inhibitors of autophagy that could improve outcomes for ovarian cancer patients. Citation Format: Janice M. Santiago-O'Farrill, Saravut J. Weroha, Xiaonan Hou, Lan Pang, Philip Rask, Zhen Lu, Robert C. Bast. PARP inhibitor-induced autophagy provides an adaptive mechanism of drug resistance in preclinical models of ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4768.