Likun Zhang

Overcoming erlotinib resistance with tailored treatment regimen in patient‐derived xenografts from naïve Asian NSCLC patients

Overall benefits of EGFR‐TKIs are limited because these treatments are largely only for adenocarcinoma (ADC) with EGFR activating mutation. The treatments also usually lead to development of resistances. We have established a panel of patient‐derived xenografts (PDXs) from treatment naïve Asian NSCLC patients, including those containing “classic” EGFR activating mutations. Some of these EGFR‐mutated PDXs do not respond to erlotinib: LU1868 containing L858R/T790M mutations, and LU0858 having L858R mutation as well as c‐MET gene amplification, both squamous cell carcinoma (SCC). Treatment of LU0858 with crizotinib, a small molecule inhibitor for ALK and c‐MET, inhibited tumor growth and c‐MET activity. Combination of erlotinib and crizotinib caused complete response, indicating the activation of both EGFR and c‐MET promote its growth/survival. LU2503 and LU1901, both with wild‐type EGFR and c‐MET gene amplification, showed complete response to crizotinib alone, suggesting that c‐MET gene amplification, not EGFR signaling, is the main oncogenic driver. Interestingly, LU1868 with the EGFR L858R/T790M, but without c‐met amplification, had a complete response to cetuximab. Our data offer novel practical approaches to overcome the two most common resistances to EGFR‐TKIs seen in the clinic using marketed target therapies.

Molecular Pathology of Patient Tumors, Patient-Derived Xenografts, and Cancer Cell Lines.

The Cancer Genome Atlas (TCGA) project has generated abundant genomic data for human cancers of various histopathology types and enabled exploring cancer molecular pathology per big data approach. We developed a new algorithm based on most differentially expressed genes (DEG) per pairwise comparisons to calculate correlation coefficients to be used to quantify similarity within and between cancer types. We systematically compared TCGA cancers, demonstrating high correlation within types and low correlation between types, thus establishing molecular specificity of cancer types and an alternative diagnostic method largely equivalent to histopathology. Different coefficients for different cancers in study may reveal that the degree of the within-type homogeneity varies by cancer types. We also performed the same calculation using the TCGA-derived DEGs on patient-derived xenografts (PDX) of different histopathology types corresponding to the TCGA types, as well as on cancer cell lines. We, for the first time, demonstrated highly similar patterns for within- and between-type correlation between PDXs and patient samples in a systematic study, confirming the high relevance of PDXs as surrogate experimental models for human diseases. In contrast, cancer cell lines have drastically reduced expression similarity to both PDXs and patient samples. The studies also revealed high similarity between some types, for example, LUSC and HNSCC, but low similarity between certain subtypes, for example, LUAD and LUSC. Our newly developed algorithm seems to be a practical diagnostic method to classify and reclassify a disease, either human or xenograft, with better accuracy than traditional histopathology. Cancer Res; 76(16); 4619-26. ©2016 AACR.

AC220 and AraC cause differential inhibitory dynamics in patient-derived M5-AML with FLT3-ITD and, thus, ultimately distinct therapeutic outcomes

Engrafting the bone marrow cells of a patient with M5 acute myeloid leukemia into immunocompromised mice (AM7577) resulted in serially transferrable stable AML and eventual mortality. The disease starts in the bone marrow and then expands to peripheral areas, which is typical of M5 leukemogenesis, where high leukemic burden in blood is coincident with symptoms/mortality. The leukemic cells in the mice had myeloid morphology, phenotypes, and genotypes (including the internal tandem duplication of FMS-like tyrosine kinase receptor 3 gene [FLT3-ITD]) similar to those of the original patient. Autocrine mechanisms of human granulocyte-macrophage colony-stimulating factor/interleukin-3 likely support AM7577 growth in mice. Treatment with FLT3 TKI (AC220) caused complete remission in peripheral blood, spleen, and bone, along with relief of symptoms and extended life, hinting that FLT3-ITD may be a key leukemogenic driver maintaining the disease. Interestingly, withdrawal of AC220 (high dose) did not result in relapse of disease, suggesting cure. These results, however, are in contrast to cytarabine (AraC) induction treatment: First, although AraC significantly suppresses the diseases in blood, and to a lesser degree in bone marrow and spleen, the suppression is temporary and does not prevent eventual onset of disease/death. Second, the withdrawal of AraC always resulted in rapid relapse in peripheral blood and eventually death. Our observation in this patient-derived model may provide useful information for clinical applications of the two drugs.

A subset of esophageal squamous cell carcinoma patient-derived xenografts respond to cetuximab, which is predicted by high EGFR expression and amplification

Background Epidermal growth factor receptor (EGFR) is reportedly overexpressed in most esophageal tumors, but most targeted therapies showed no efficacy in non-selected patients. This study aims at investigating the adaptive cetuximab subset in a cohort of esophageal squamous cell carcinoma (ESCC) patient-derived xenografts (PDXs). Methods A large panel of ESCC PDXs has been established. The copy number, mRNA expression and immunohistochemistry (IHC) of key EGFR pathways have been examined along with cetuximab response. A preclinical trial on a randomly selected cohort of 16 ESCC PDXs was conducted, and the genomic annotations of these models were compared against the efficacy readout of the mouse trial. Results The trial identified that 7 of 16 (43.8%) responded to cetuximab (ΔT/ΔC <0 as responders). The gene amplification and expression analysis indicated that EGFR copy number ≥5 (P=0.035), high EGFR mRNA expression (P=0.001) and IHC score of 2-3 (P=0.034) are associated with tumor growth inhibition by cetuximab, suggesting EGFR may function as a single predictive biomarker for cetuximab response in ESCC. Conclusions Overall, our results suggest that an ESCC subtype with EGFR amplification and overexpression benefits from cetuximab treatment, which warrants further clinical confirmation.

Abstract 2167: Efficacy assessment of BTK inhibitor ibrutinib in de novo and viral-induced B cell lymphoma

Bruton9s tyrosine kinase (BTK) is crucial for B cell maturation. Its activation has also been considered as a major oncogenic driver for various B cell-derived lymphoid cancers. A BTK inhibitor, Ibrutinib, has been approved for mantle cell lymphoma, chronic lymphocytic leukemia, and Waldenstrom9s macroglobulinemia, a form of non-Hodgkin9s lymphoma (NHL). Ibrutinib has also shown encouraging efficacies in defuse large B cell lymphoma (DLBCL), specifically in activated B cell-like (ABC) subtype, but not in germinal center B cell-like (GCB) subtype. We have established a series of patient derived xenograft (PDX) models, recapitulating diverse genotypes of de novo DLBCL patients, including two MYD88 L265P /CD79B Y197N double mutants (LY2298, LY2264), one MYD88 L265P single mutant (LY0257), and a variety of wild-types (LY2214, LY3604, and LY6934, etc.). This cohort of PDX models serve as perfect preclinical tools to investigate Ibrutinib responses in different genotypes. Our studies demonstrated a moderate to robust efficacies of Ibrutinib in the MYD88/CD79B double mutants, suggesting that CD79B mutation is the predictive biomarker for chronic activation of B cell receptor (BCR) signaling, as well as generally good responses to BTK inhibitor. Interestingly, the MYD88 single mutant model LY0257, where the disease is likely driven by constitutive activation of MYD88 signaling, also showed response to Ibrutinib when dosed in drinking water. In the wild type PDXs, two of seven models tested so far are either partially responsive or sensitive to Ibrutinib, while the others are resistant to the treatment. It seems that Ibrutinib response does not always require CD79B mutation, and BCR pathway addiction may occur by other means in DLBCL, even when MYD88 signaling is constitutively active. Notably, all 5 wild type DLBCL PDXs that are non-responsive to Ibrutinib are EBV positive verified by RNAseq. These EBV-transformed B lymphoma PDX models, which share the similar histopathology as de novo DLBCL, but have distinct molecular pathology signatures and different pathogenesis. In efficacy studies, none of the transformed B lymphoma PDXs showed response to Ibrutinib. Taken together, our DLBCL and EBV-induced lymphoma PDX models provide a valuable preclinical platform for evaluating BTK inhibitors, as well as future drug discovery efforts on other targets in the BCR and MYD88 pathways, such as PI3K, SYK, and IRAK4. Citation Format: Jessie Jingjing Wang, Meiling Zheng, Xuesong Huang, Yanrui Song, Wubin Qian, Likun Zhang, Jie Cai, Sheng Guo, Henry Qixiang Li, Davy Xuesong Ouyang. Efficacy assessment of BTK inhibitor ibrutinib in de novo and viral-induced B cell lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2167.

Abstract A30: Modeling an immunotherapy of NK mechanism on a NSCLC patient derived xenograft

The recent clinical successes of immune checkpoint inhibitors have fueled the intense interest in novel immuno-oncology (I/O) therapeutics. The lack of relevant animal models remains a major hurdle in understanding the mechanism of action and evaluating the efficacy of such therapeutics. Patient derived xenograft (PDX), considered to most closely mimic patient tumors in both histo- and molecular pathology1,2, is however rarely used in I/O studies because it grow only in immune-compromised hosts. In reality, many PDXs grow well in nude mice where certain immune functions remain intact, excluding T-cells/T-cell functions. Therefore, PDX could still potentially be of practical use for studying T-cell independent I/O therapy. This study set out to evaluate a biologics for the treatment of a patient derived xenograft disease, by activating mouse natural killer (NK). NK and CD8 T cells are two major immune effector cell types that mediate cytotoxicity to tumor cells in vivo. One of the immunomodulatory agents, an anti-PD-L1 antibody-based IL-15 immunocytokine, was recently tested as a novel I/O treatment of cancer3. This molecule was engineered to be cross-species for both human and mouse PD-L1 and IL-15 that antagonize PD1/PD-L1 checkpoint-mediated immune suppression and also target the PD-L1-expressing tumor with IL-15 stimulated NK and CD8 T effector cells into local tumor sites, thus synergizing tumor-located anti-tumor immunity. In fact, our previous studies have demonstrated a greatly enhanced anti-tumor activity in the PDL-1-expressing syngeneic mouse tumor models via the mobilization of tumor infiltrating lymphocyte (TILs), over the PD-L1 antibody alone3. Since IL-15 also stimulates NKs in addition to T-cells, we reasoned that this bifunctional agent could also have potential activity against a PD-L1-expressing PDX in nude mice where NK remains functional. LU1901 is previously described NSCLC-PDX1, and was confirmed to express high level of PD-L1 by both RNAseq and flow analysis, after screening of a large panel of PDXs. We implanted LU1901 in Balb/c nude mice, and started to treat the mice by the bifunctional agent when the tumor reached to 150 mm3. Our result clearly demonstrated a significant inhibition of LU1901 growth by the bifunctional agent in nude mice, in the apparent absence of T-cells. When the treated tumors were examined at the termination, significantly infiltrate NK cells were found inside the treated tumors, as measured by both flow cytometry and immunohistochemistry (IHC). The number of infiltrating NK also statistically correlates to the amplitude of the tumor responses. Together, our data suggest that one of important mechanisms of action of this bifunctional agent relies on the tumor-targeting NK activation, and also that PDX could be a useful model suitable for in vivo efficacy analysis of T-cell independent immunotherapy. References 1. Yang, M., et al. Overcoming erlotinib resistance with tailored treatment regimen in patient-derived xenografts from naive Asian NSCLC patients. International journal of cancer. Journal international du cancer 132, E74-84 (2013). 2. Guo, S., Wubin Qian, Jie Cai, Likun Zhang, Jean-Pierre Wery, Qi-Xiang Li. Molecular pathology of patient tumors, patient derived xenografts and cancer cell lines EORTC-NCI-AACR. (2015). 3. Yan Wu, Zhaojing Zhong, Stella Martomo, Dan Lu, Zhanna Polonskaya, Xenia Luna, Haifan Zhang, Zhikai Zhang, Zhun Wang*, Leo Liu*, Jeegar Patel, James Tonra, Henry Li*, Larry Witte, Sam Waksal, Zhenping Zhu. Anti-PD-L1 antibody-based IL-15 immunocytokine has enhanced antitumor immunity. EORTC-NCI-AACR Abstract (2015). Citation Format: Henry Q. Li, Zhun Wang, Xiaoyu An, Jinping Liu, Likun Zhang, Jean-Pierre Wery, Yan Wu, James Tonra, Sam Waksal, Zhenping Zhu. Modeling an immunotherapy of NK mechanism on a NSCLC patient derived xenograft. [abstract]. In: Proceedings of the AACR Special Conference: Patient-Derived Cancer Models: Present and Future Applications from Basic Science to the Clinic; Feb 11-14, 2016; New Orleans, LA. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(16_Suppl):Abstract nr A30.

Abstract 3219: Prior vaccination is critical to PD1/PDL-1 treatment efficacy in a mouse breast cancer allograft

We previously generated the MuPrime® mBR6004 model, by engrafting the breast adenocarcinoma derived from MMTV-PyVT transgenic mice (GEMM)1 into the syngeneic FVB/N mice2,3. The allograft grows robustly, maintains the histopathology features of the original GEMM, and metastasizes to the lungs in all examined cases when implanted orthotopically2. Additionally, histopathology shows that the models is HER2++, but ER-/PR-. We profiled drug responses to standard of care (SoC)2 and checkpoint inhibitors3. Interestingly, among all checkpoints inhibitors tested, our model is insensitive to PD1/PDL-1 inhibitors, but responds to CTLA-4 inhibitors3. To further explore the underlying mechanism of response, we performed extensive tumor immuno-profiling for the presence of infiltrating immune cells, e.g. TIL, CTL, Treg, immune-suppressive macrophages, NK, etc3. We observed a good pharmacodynamic (PD) correlation between the presence of tumor infiltrating T-cells, particularly CD8+ TIL, and NK and a positive response to therapy, regardless the treatment type. Given this preliminary observation, we attempted animal vaccination with tumor lysates prior to tumor engraftment or treatments. Interestingly, while vaccination had minimal effects on the engraftment take rate (100% take for all animals) and on the growth kinetics of the engraftments, it had profound effects on the tumor response to anti-PD1/anti-PDL-1 antibody treatments, significantly enhancing tumor response to these agents in a model that was otherwise unresponsive. Our results suggest that the immunological status of the animal, at least with regard to the specific anti-tumor immunity, is critically important to determine the response to checkpoint inhibitors. Our observations suggest that vaccination is critical for the overall success of immunotherapy (I/O) treatments utilizing checkpoint inhibitors as well other treatment strategies. References 1. Guy, C.T., Cardiff, R.D. & Muller, W.J. Induction of mammary tumors by expression of polyomavirus middle T oncogene: a transgenic mouse model for metastatic disease. Molecular and cellular biology 12, 954-961 (1992). 2. Annie Xiaoyu An1, Jinping Liu1, Jie Cai1, Jean Pierre Wery1, and Henry Q.X. Li1,. Building mouse tumor derived allogragfts for immune-oncology research. (2015). 3. Zhun Wang1, A.X.A., 2*, Jinping Liu1, Gavin Jiagui Qu1, Likun Zhang, Jie Cai1, Bin Chen1, Davy Xuesong Ouyang1, Jean Pierre Wery1, and Henry Q.X. Li1,2. Response to checkpoint inhibition by GEMM breast cancer allograft EORTC-AACR-NCI Abstract (2015). Citation Format: Zhun Wang, Xiaoyu An, Jinping Liu, Xuesong Ouyang, Jiagui Qu, Likun Zhang, Jie Cai, Jean-Pierre Wery, Henry Li. Prior vaccination is critical to PD1/PDL-1 treatment efficacy in a mouse breast cancer allograft. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3219.

Abstract 747: Paracrine c-MET/HGF HCC PDX: evaluation of a biologics targeting c-MET

The interaction between the c-MET tyrosine kinase receptor (RTK) on the surface of cancer cells with its ligand, hepatocyte growth factor (HGF) secreted from surrounding tumor stroma, results in paracrine signal transduction in cancer cells to promote growth, invasion, angiogenesis and metastases. c-MET gene amplification/over-expression, or activating mutations, frequently function as oncogenic driver in several types of cancers. c-MET is thus considered a key target(1) for both TKIs or biologics. However, lack of suitable animal models has represented an obstacle for the development of new cMET inhibitors. While patient derived xenografts (PDXs) mirror patients’ histopathological/genetic profiles(2-6), they usually lose human stroma, the source of HGF; moreover the HGF originated from murine stroma is incapable of triggering a paracrine signaling because of lack of cross reactivity with the human c-MET. Some PDX grow independent of paracrine mechanisms because of their constitutive c-MET activation by the presence of activating mutations, gene amplification or autocrine signaling, and can be used to evaluate the efficacy of TKIs(5, 7, 8). However they are not suitable to assess biologics, e.g. antibodies disrupting receptor-ligand interaction. Alternatively it is possible to grow tumors in hu-HGF-transgenic immunocompromised mice (humanization) where an artificial paracrine signaling is created. Interestingly, we have identified a unique HCC-PDX, LI0801, which maintains human stroma throughout passages, as demonstrated by immunochemistry staining for human vimentine and human HGF, both markers of stromal components(7, 8). The mechanisms of human stroma maintenance in this PDXremain unclear. We showed that LI0801 responds to different TKIs(7, 8). In addition we evaluated the efficacy of an anti-human c-MET monoclonal antibody in reducing tumor burden in LI0801, and we were able to demonstrate great tumor response to anti-human c-MET antibody, which is significantly more effective than crizotinib. To the best of our knowledge, LI0801 is the first paracrine c-MET PDX reported, and represents an important model to study paracrine cMET/HGF signaling and to evaluate new c-MET inhibitors, both TKIs, and biologics. References 1. Comoglio PM, et al. Nat Rev Drug Discov. 2008;7:504-16. 2. Ding L, et al. Nature. 2010;464:999-1005. 3.Marangoni E, et al. A new model of patient tumor-derived breast cancer xenografts for preclinical assays. Clin Cancer Res. 2007;13:3989-98. 4.Chen D, Oncotarget. 2015. 5. Yang M, et al. International journal of cancer Journal international du cancer. 2013;132:E74-84. 6. Zhang L, et al. A subset of gastric cancers with EGFR amplification and overexpression respond to cetuximab therapy. Sci Rep. 2013;3:2992. 7. Bladt F, et al. Cancers (Basel). 2014;6:1736-52. 8. Chen D. AACR Annual Meeting 2012. 2012;Poster. Citation Format: Dawei Chen, Ziyong Sun, Likun Zhang, Jie Cai, Davy X. Ouyang, Jean-Pierre Wery, Henry Li. Paracrine c-MET/HGF HCC PDX: evaluation of a biologics targeting c-MET. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 747.

Abstract 4043: Establishment of a mouse skin squamous cell carcinoma allograft model for in vivo pharmacological analysis of immunotherapy

Proceedings: AACR 107th Annual Meeting 2016; April 16-20, 2016; New Orleans, LA The recent clinical success of novel therapeutics blocking immune checkpoints cytotoxic T-lymphocyte associated antigen 4 (CTLA-4) and programmed cell death 1 (PD-1) has fueled an intense interest around immuno-oncology. However, the lack of relevant animal models is a major bottleneck for understanding the mechanism of action and evaluating the efficacy of such therapeutics. Syngeneic mouse tumor models, despite being widely used as experimental models for efficacy studies, are limited by the restricted number of models available and responsive to current checkpoint inhibitors. Genetically engineered mouse models (GEMMs) of human cancer are effective tools for mechanistic analysis, but they are often not suitable for efficacy studies due to usually un-synchronized tumor progression. Syngeneic allografts of spontaneous mouse tumors derived from GEMMs (MuPrime®) may be used as a new type of immuno-oncology models with the following advantages: 1) their primary nature of “stem cell diseases” and relevant tumor microenvironment mirror the patient derived xenograft (PDX) models; 2) the availability of diverse cancer types and oncogenic drivers deriving from a wide range of GEMMs. We set out to build a library of allografts of spontaneous mouse tumors, including those derived from GEMM, in an immunocompetent host to support pharmacological investigation, particularly of immuno-oncology agents. Recently, we observed the growth of spontaneous cutaneous tumors on the neck of the C57BL/6J-ApcMin/J GEMM, which is heterozygous for the Apc (APCMin/+). Histopathology suggests the tumors are well-differentiated skin squamous cell carcinoma. We subcutaneously transplanted these skin tumors into the syngeneic C57BL/6J mice. The allografts grow well, are serially transplantable and maintain the histopathology of the primary tumor. Transcriptome sequencing revealed that the allografts maintain the original ApcMin mutation, express high levels of HER2 (also confirmed by immunochemistry, or IHC), and present frameshift mutations in both c-met and EGFR. In vivo pharmacological assessment indicate that tumors respond to 5-FU, paclitaxel, gemcitabine, docetaxel, and cisplatin chemotherapy. They is also sensitive to anti-mouse CTLA-4 antibody, and the response is associated with an increased number of tumor infiltrating immune cells, including TILs. Alltogether, here we show that we have established an allograft model suitable for in vivo efficacy analysis of immunotherapy using surrogate anti-mouse antibodies. Citation Format: Gavin Jiagui Qu, Annie Xiaoyu An, Jinping Liu, Davy Xuesong Ouyang, Likun Zhang, Jie Cai, Jean Pierre Wery, Henry Q. X. Li. Establishment of a mouse skin squamous cell carcinoma allograft model for in vivo pharmacological analysis of immunotherapy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4043.

Abstract B101: Molecular pathology of patient derived xenografts

Background. The Cancer Genome Atlas (TCGA) and many other genomic profiling of patient samples generated abundant human cancer genomic datasets of various histological types and individual patients, enabling development of molecular pathology methodology per big data fashion1-4. Patient derived xenograft (PDX) is believed to mimic patient tumors with anecdotal data, and assumed to be predictive experimental models (avatar) for human trial. There is also a need to investigate tumor pathology among different histopathology types, either patient or xenograft diseases, per “big data” approach. Methods. We first systematically compared transcriptome expression similarity within and between specific histological types using either global or specific subsets of genes using the datasets from TCGA. We next investigated PDXs (also cell lines) using the same systemic approaches. Results. We demonstrated the presence of highly consistent correlation in transcriptome expression within a given histology types, but more distinct between the types, establishing molecular specificity alternative to histological type based on morphology, or an alternative diagnostic approach. We performed the same systematic examination of PDXs of different histological types corresponding to the TCGA types. The similar general pattern of similarity, also somewhat reduced in degree, have been observed. These suggest the high relevance of PDX to human cancer tissues in general from “big data” perspective. In contrast, this seems generally untrue for cancer cell lines: quite similar among themselves even for different histological types, but less correlation to either TCGA or PDXs per disease type. The similarity among cell lines of all types may suggest a “new type of cancer, or tissue culture type”. Our studies also revealed certain specific correlations, with several examples: 1) colon and rectal adenocarcinoma are highly correlated, without apparent difference; 2) NSCLC SCC are quite different from NSCLC ADC, as seen morphologically; 3) NSCLC SCC are also quite closely related to HNSCC. Conclusion. There are generally good correlation between transcriptome expression based molecular pathology and histopathology; the molecular pathology of PDXs are generally similar to that of human9s, not so to human cell lines. References 1. Comprehensive molecular characterization of gastric adenocarcinoma. Nature 513, 202-209 (2014). 2. Hoshida, Y., et al. Integrative transcriptome analysis reveals common molecular subclasses of human hepatocellular carcinoma. Cancer research 69, 7385-7392 (2009). 3. Comprehensive genomic characterization defines human glioblastoma genes and core pathways. Nature 455, 1061-1068 (2008). 4. Ge, L., et al. Integrated analysis of gene expression profile and genetic variations associated with ovarian cancer. European review for medical and pharmacological sciences 19, 2703-2710 (2015). Citation Format: Sheng Guo, Wubin Qian, Jie Cai, Likun Zhang, Jean-Pierre Wery, Henry Li. Molecular pathology of patient derived xenografts. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B101.