Doroshow, James H.

1043 Background: In estrogen receptor (ER) positive MBC, mutations (e.g. ESR1), identified from tumor biopsies or cfDNA, confer resistance. The concordance between mutations observed in tumor and cfDNA and the implications for response to Z-endoxifen, a potent anti-estrogen, are unknown. Methods: We previously conducted a phase I trial of Z-endoxifen in endocrine refractory, ER positive MBC. Seven dose levels were considered ranging from 20 to 160 mg/day followed by expansion cohorts (EC) of 40, 80, and 100 mg/day. Pretreatment blood samples (all pts) and fresh tumor biopsies (EC) were collected prospectively. Tumor and cfDNA were evaluated by targeted NGS. Results: 41 pts (38 evaluable) were enrolled. Prior endocrine therapy included aromatase inhibitors (37/38, 97%), fulvestrant (22/38, 58%) and tamoxifen (26/38, 68%). Substantial endoxifen exposure without DLTs at doses above 80 mg/day led to a halt in dose escalation and opening of the EC. Overall clinical benefit (stable > 6 months [7 pts.] or partial response by RECIST criteria [3 pts.]) rate was 26.3% (95%CI: 13.4-43.1%). cfDNA was obtained from 36 pts and mutations were identified in 13 (36%) including ESR1 [ Y537N or D538G] (5), PIK3CA [ H1047R or E542K] (8), TP53 [ K132R, R248Q, R267Q, or H179Y] (4), AKT ( Q79K) (1), and KRAS ( G12D) (1). In 5 pts with cf ESR1 mutations, 4 had additional cfDNA mutations including PIK3CA (3), and TP53 (1). PFS was shorter in pts with cfDNA mutations relative to those without (median: 61 vs.132 days; log-rank p = 0.021). Discordance was observed between tumor and cfDNA mutations where 3/7 PIK3CA tumor mutations were detected by cfDNA, 1/2 TP53 tumor mutations were detected by cfDNA, and 0/1 AKT tumor mutations were detected by cfDNA. Conversely, 2 pts had cfDNA mutations (either ESR1, TP53 or AKT) undetected in tumor. Conclusions: The absence of cfDNA mutations in patients with endocrine resistant, MBC treated with Z-Endoxifen was associated with significantly longer PFS. Given the discordance between tumor and cfDNA sequence data, future studies must determine which approach maximizes prognosis and prediction of benefit for estrogen-targeted therapy. Clinical trial information: NCT01327781.

Abstract Patient-derived tumor xenograft (PDX) mouse models have emerged as an important oncology research platform to study tumor evolution, mechanisms of drug response and resistance, and tailoring chemotherapeutic approaches for individual patients. The lack of robust standards for reporting on PDX models has hampered the ability of researchers to find relevant PDX models and associated data. Here we present the PDX models minimal information standard (PDX-MI) for reporting on the generation, quality assurance, and use of PDX models. PDX-MI defines the minimal information for describing the clinical attributes of a patient's tumor, the processes of implantation and passaging of tumors in a host mouse strain, quality assurance methods, and the use of PDX models in cancer research. Adherence to PDX-MI standards will facilitate accurate search results for oncology models and their associated data across distributed repository databases and promote reproducibility in research studies using these models. Cancer Res; 77(21); e62–66. ©2017 AACR.

Purpose Endoxifen is a tamoxifen metabolite with potent antiestrogenic activity. Patients and Methods We performed a phase I study of oral Z-endoxifen to determine its toxicities, maximum tolerated dose (MTD), pharmacokinetics, and clinical activity. Eligibility included endocrine-refractory, estrogen receptor–positive metastatic breast cancer. An accelerated titration schedule was applied until moderate or dose-limiting toxicity occurred, followed by a 3+3 design and expansion at 40, 80, and 100 mg per day. Tumor DNA from serum (circulating cell free [cf); all patients] and biopsies [160 mg/day and expansion]) was sequenced. Results Of 41 enrolled patients, 38 were evaluable for MTD determination. Prior endocrine regimens during which progression occurred included aromatase inhibitor (n = 36), fulvestrant (n = 21), and tamoxifen (n = 15). Patients received endoxifen once daily at seven dose levels (20 to 160 mg). Dose escalation ceased at 160 mg per day given lack of MTD and endoxifen concentrations > 1,900 ng/mL. Endoxifen clearance was unaffected by CYP2D6 genotype. One patient (60 mg) had cycle 1 dose-limiting toxicity (pulmonary embolus). Overall clinical benefit rate (stable > 6 months [n = 7] or partial response by RECIST criteria [n = 3]) was 26.3% (95% CI, 13.4% to 43.1%) including prior tamoxifen progression (n = 3). cfDNA mutations were observed in 13 patients ( PIK3CA [n = 8], ESR1 [n = 5], TP53 [n = 4], and AKT [n = 1]) with shorter progression-free survival ( v those without cfDNA mutations; median, 61 v 132 days; log-rank P = .046). Clinical benefit was observed in those with ESR1 amplification (tumor; 80 mg/day) and ESR1 mutation (cfDNA; 160 mg/day). Comparing tumor biopsies and cfDNA, some mutations ( PIK3CA, TP53, and AKT) were undetected by cfDNA, whereas cfDNA mutations ( ESR1, TP53, and AKT) were undetected by biopsy. Conclusion In endocrine-refractory metastatic breast cancer, Z-endoxifen provides substantial drug exposure unaffected by CYP2D6 metabolism, acceptable toxicity, and promising antitumor activity.

Abstract Background: Breast cancer recurrence has been shown to differ based upon CYP2D6 genotype and endoxifen (Endx) exposure following treatment with tamoxifen (TAM) in the adjuvant setting. The average Endx Css is 29 nM (range, 2-80 nM) in TAM treated patients at a dose of 20 mg/day. Administration of Endx itself to patients is predicted to provide adequate, consistent, active drug levels in all treated patients, resulting in clinical benefit. As part of two phase 1 trials of oral Endx to determine the safety, tolerability, and MTD, we characterized the pharmacokinetics and in vivo metabolism of Endx. Methods: Patients were given escalating daily oral doses of Endx (28 day cycle) over the dose range of 20 - 160 mg/day in Phase I trials at the Mayo Clinic and NCI. Pharmacokinetics sampling was performed on days 1, 7, 14 and 28, and prior to subsequent cycles. Endx plasma concentrations and metabolite profiles were determined by HPLC and LC/MS/MS. Results: 44 patients with ECOG PS 0-1 have been enrolled to date encompassing 8 dose levels in the Mayo (25 women with AI refractory MBC; median age 58 yrs, range 41-83 yrs) and NCI (19 women with ovary (9), breast (4), desmoid (2), fallopian tube (2), endometrial cancer (2); median age 64 yrs, range 43-75 yrs) studies. Day 1 Endx peak concentrations (Cmax) were reached 4h after the Endx oral dose and mean values of Cmax, C24h, and AUC0-24h increased in proportion to dose. Css was achieved on day 7 and 3.5-fold accumulation (t1/2= 50.5 h) was observed on day 28. At the starting dose ( 20 mg/day) and highest dose level (160 mg/day), Endx Css values of 146 ng/ml (390 nM) and 1950 ng/ml (5200 nM), respectively, were achieved and maintained throughout the 28-day treatment. Endx Css values remained unchanged following continuous dosing for 8-10 months. The mean apparent steady-state clearance was 6.2 L/h. We also characterized the Endx metabolite profile in patient plasma and urine. Metabolites detected in plasma include nor-Endx, N-hydroxy-Endx, Endx-catechol, methoxy-Endx catechol, and Endx-glucuronide, and appear in amounts much lower compared to Endx. Like the parent drug, metabolites accumulated in plasma over the 28-day cycle. Characterization of the pharmacokinetics of Nor-Endx, a putative aromatase inhibitor, is ongoing and will be presented. Conclusion: In these ongoing Phase I studies, daily administration of Endx is well tolerated with Css consistently above those obtained following administration of standard dose tamoxifen. In the Mayo study, expansion at 20 and 100 mg/day has commenced to perform translational studies and further characterize Endx PK. In the NCI study, dose escalation continues to establish the maximum tolerated dose. Supported in part by R01CA 133049, U01 CA69912, P30CA 15083, P50CA 116201 and NCI Contracts CM52206 and HHSN261201100014C. Citation Format: Joel M. Reid, Matthew P. Goetz, Shivaani Kumar, Renee M. McGovern, Sarah A. Buhrow, Stephanie L. Safgren, Vera J. Suman, Travis J. Docktor, Charles Erlichman, Howard Streicher, James H. Doroshow, Jerry Collins, Matthew M. Ames. Pharmacokinetics and in vivo metabolism of Z-endoxifen: Results from two phase I studies in women with ER+ breast cancer, gynecologic malignancies and desmoids. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4631. doi:10.1158/1538-7445.AM2014-4631

Abstract High-throughput data is increasingly being integrated into the fields of biology, molecular biology, and pharmacology. However, a difficult problem has been the rapid and fluid access to and integration of the data, which tends to reside in huge unwieldy databases. One set of cell lines with substantial potential for benefit from this type of access and integration is the NCI-60 cancerous cell lines. We present here a set of tools within our CellMiner web-application designed to address this need for the areas of transcript expression, microRNA expression, gene DNA copy number, variant status, and drug activity. CellMiner allows the user to rapidly access data for relative levels of transcript expression for 26,065 genes, 360 microRNAs, and 20,602 compounds including 102 Food and Drug Administration (FDA)-approved drugs. These levels in turn create patterns across the NCI-60 that can be compared to one another using our “pattern match” tool. Together, these tools allow one to query the data for potential relationships between these parameters, in a manner specific to a users area of expertise and interest, in a rapid and flexible manner without the need for expertise in computer science or bioinformatics. Comparisons of transcript/drug will be demonstrated with SLFN11/topotecan; variant/drug with BRAF V600E/vemurafinib; colon tissue-of origin specific genes with TRIM15, RNF43, and VIL1; and DNA copy number change with CDKN2A (p16). The data are publicly available at http://discover.nci.nih.gov/cellminer. Citation Format: William C. Reinhold, Margot Sunshine, Sudir Varma, Hongfang Liu, Ogan Abaan, Paul Meltzer, Joel Morris, Kurt Kohn, James Doroshow, Yves Pommier. Web-based access using CellMiner for gene expression, DNA copy number, microRNA transcript levels, variant status, drug activity, and their pattern comparisons for the NCI-60. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3177. doi:10.1158/1538-7445.AM2013-3177

Abstract High-throughput data is increasingly being integrated into the fields of biology, molecular biology, and pharmacology. However, a difficult problem has been the rapid and fluid access to and integration of this data, which tends to reside in huge unwieldy databases. One set of cell lines with substantial potential for benefit from this type of access and integration is the NCI-60 cancerous cell lines. We present here a set of tools within our CellMiner web-application designed to address this need for the areas of transcript expression, microRNA expression, gene DNA copy number, and drug activity. CellMiner allows the user to rapidly access data for relative levels of transcript expression for 18,532 genes, 360 microRNAs, and 16,861 compounds including 91 Food and Drug Administration (FDA)-approved drugs. These levels in turn create patterns across the NCI-60 that can be compared to one another using our “pattern match” tool. Together, these tools allow one to query the data for potential relationships between these parameters, in a manner specific to a users area of expertise and interest, in a rapid and flexible manner without the need for expertise in computer science or bioinformatics. The output will be demonstrated with cancer interesting microRNAs 18a, 21, 29a, 30c-2, 30d, and 31, cancer interesting genes ABCB1, ATM, ATR, BRCA2, and TP53, and the clinically relevant drugs belinostat, crizotinib, pazopanib, selumetinib and tanespimycin. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2991. doi:1538-7445.AM2012-2991

Abstract CHEK2 codes for a serine/threonine kinase (Chk2) activated by ATM in response to DNA double-strand breaks (DSB). CHEK2 has been described as a tumor suppressor with pro-apoptotic, cell cycle checkpoint and mitotic functions. However, Chk2 is also commonly activated (phosphorylated at T68) in cancers and precancerous lesions. In the present report, we characterized CHEK2 across the panel of 60 established cancer cell lines from the NCI Anticancer Tumor Cell Line panel (the NCI-60) using genomic and proteomic analyses including exon-specific mRNA expression, DNA copy number variation (CNV) by aCGH, exome sequencing, as well as Western blotting analyses for total and activated (pT68-Chk2) Chk2. We demonstrate that the high heterogeneity of Chk2 levels in the NCI-60 is primarily due to its inactivation (owing to low gene expression, alternative splicing, point mutations, copy number alterations and premature truncation) or reduction of protein levels. Notably, we also found that a significant percentage of cancer cells (12% of the NCI-60 and the HeLa cervix cell line) display high endogenous Chk2 activation, always associated with p53 loss of function. Notably, all the 12 cancer cell lines characterized as being p53 wild-type showed almost undetectable levels of pT68-Chk2. The potential impact of endogenous Chk2 activation was analyzed by transcriptome profiling of the five highest pT68-Chk2 cell lines, comparing them with five, tissue-matched low pT68-Chk2 and p53-matched deficient cell lines. Two-sided t tests revealed 176 genes differentially expressed with statistical significance (P < 0.01, uncorrected) in the two groups (high vs. low pT68-Chk2). Among the downregulated expressed genes, a significant number codes for proteins involved in DNA recombination, replication and repair (FANCA, FANCG, FANCL, BRCA2, RAD51C, EME1, and RECQL5 being the most relevant), and centromere organization. Several of these downregulated genes were parts of the Fanconi Anemia pathway or related to homologous recombination (HR, P < 0.05 for statistically significant enrichment using Ingenuity Pathway Analysis®). In conclusion, the biology of Chk2 remains complex, multifaceted and fast evolving. Our study provides information on the relationship between different genomic and proteomic parameters related to Chk2 in cancer, and suggests a possible role for activated Chk2 in p53-deficient or HR/Fanconi Anemia-deficient cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2116. doi:1538-7445.AM2012-2116