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Background Patients with advanced non-small cell lung cancer (NSCLC) harboring oncogenic MET alterations, such as MET exon 14 skipping or MET amplification (MET amp), benefit from MET tyrosine kinase inhibitor (TKI) treatment. Brain metastases are common in patients with advanced NSCLC. In preclinical studies in rats, tepotinib had relatively high binding to brain tissue (fu br=0.4%, fu pl=4%) and free tepotinib concentrations in brain were 25% of the concentrations found in plasma (Kp u,u=0.25). In this study we investigated the efficacy of the MET TKIs tepotinib, capmatinib, savolitinib and crizotinib in mice implanted orthotopically with MET-dependent tumor explants derived from human NSCLC brain metastases. Methods The antitumor activity of tepotinib (30 mg/kg qd) was investigated in a screen of 21 subcutaneous lung cancer patient-derived xenograft (PDX) models of brain metastases grown in NOD-SCID mice (n=1/model). 20 of these tumors were retrospectively analyzed for cancer-specific mutations, gene copy number (GCN) and gene expression by Nanostring. 2 responding models, both found to harbor MET amp, were tested again subcutaneously in NOD-SCID mice treated with vehicle or tepotinib (125 mg/kg qd; n=5). Both models were orthotopically implanted into brains of NOD-SCID mice and tumor growth was monitored by MRI. Established tumors were treated with MET TKIs (n=10) tepotinib (125 mg/kg qd), capmatinib (30 mg/kg bid), savolitinib (60 mg/kg qd) or crizotinib (50 mg/kg qd). Results 2 of 21 subcutaneous PDX tumors (LU5406 and LU5349) regressed in response to tepotinib treatment. When implanted subcutaneously again into mice, both models regressed completely upon treatment with tepotinib. Molecular profiles revealed that these were the only tumors of the 20 models investigated by Nanostring that had MET amp (high-level increase in MET GCN of >10). Both models grew orthotopically when implanted into brains of mice. Contrast-weighted MRI indicated regions with intact and disrupted blood–brain barrier (BBB) in all implanted tumors. Tumor regression of orthotopic LU5406 tumors was observed with all MET TKIs (% median tumor volume changes [%TV]: tepotinib, –63%; capmatinib, –24%; savolitinib, –38%; crizotinib, –27%). In the orthotopic LU5349 tumors, treatment with crizotinib or savolitinib led to growth inhibition (%TV: +88% and –13%, respectively), whereas tepotinib and capmatinib induced tumor regression (%TV: –84% and –63%, respectively). Conclusions The heterogenous pattern of regions with intact and disrupted BBB in the orthotopic brain metastases models is thought to mirror the clinical situation. Tepotinib was efficacious in the two MET-driven orthotopic brain metastases PDX tumors characterized by pronounced tumor regression and may be relevant to patients with brain metastases. Relationships between efficacy and BBB leakiness will be discussed. Citation Format: Manja Friese-Hamim, Anderson Clark, Lindsey Crowley, Christof Reusch, Olga Bogatyrova, Claudia Wilm, Hong Zhang, Timothy Crandall, Jing Lin, Jianguo Ma, David Bachner, Jürgen Schmidt, Martin Schaefer, Christopher Stroh. Anti-tumor activity of tepotinib in orthotopic models of lung cancer patient-derived brain metastases with MET amplification [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 3407.

M2698 is a potent and selective, ATP-competitive dual inhibitor of p70S6K and AKT1/3 that is being evaluated in a phase I clinical trial in cancer patients. Dual pathway inhibition by M2698 may result in improved clinical efficacy by inhibiting downstream pS6 and blocking the increased AKT activity that results from a compensatory feedback loop induced by PI3K/AKT/mTOR (PAM) pathway inhibition. In earlier studies, combination efficacy was observed with M2698 and trastuzumab in HER2+ breast cancer patient derived xenograft (PDX) models, including complete tumor regressions (Huck, BR. et.al. 105th AACR; 2014: Abstract 4516). To explore the potential combination effects in gastric cancer (GC), we evaluated the effect in in vitro and in vivo GC models. Ten human GC cell lines, which included two HER2+ lines, were treated with M2698 and trastuzumab over various concentrations and cellular proliferation was examined with a WST-8 assay. Combination effects were evaluated by Bliss independence scores and highest single agent (HSA) models. The OE-19 HER2+ cell line had the greatest Bliss and HSA sum values, whereas these measures in the other HER2+ cell line, NCI-N87, were among the lowest in the set of 10 lines, indicating that the combination is synergistic in some HER2+ GC cell lines, such as OE-19. The effects of this combination on downstream markers were analysed by Western blotting. Expression of pS6 was reduced in OE-19 cells by treatment with M2698, but pAKT and pERK were both increased. Upregulated pAKT is a known compensatory feedback mechanism that is inhibited by the dual nature of M2698. Upregulated pERK is a candidate resistance marker for PI3K pathway inhibition. However, the combination of trastuzumab with M2698 blocked this increase in pERK, suggesting that dual inhibition of the MAPK and PAM pathways may contribute to the synergistic anti-proliferative effects. The combination was then tested in the OE-19 xenograft model in vivo and significantly inhibited tumor growth compared to vehicle treatment and monotherapies (p0.05). In an in vivo pharmacodynamic study, the combination of M2698 and trastuzumab inhibited pS6 and pERK showing effective PI3K and MAPK pathway inhibition by the combination. The agents were also tested alone and in combination (n=3/treatment group) in 27 PDX models of GC in mice (ChemPartner, Shanghai, China). The tumor control rate (tumor stasis or regression) was 11% (3/27) of models treated with M2698, 15% (4/27) with trastuzumab treatment and 22% (6/27) with the combination. The PDX models are currently being evaluated for HER2 status to determine the correlation with the efficacy of the treatments. Based on the data from the OE-19 model, pERK is a candidate marker of combination efficacy which can be further explored in additional GC models. Citation Format: Shota Fukuoka, Takashi Kojima, Yoshikatsu Koga, Mayumi Yamauchi, Masahiro Yasunaga, Yasuhiro Matsumura, Kohei Shitara, Toshihiko Doi, Takayuki Yoshino, Toshio Kuronita, Anderson Clark, Brian Elenbaas, Hong Zhang, Atsushi Ohtsu. Preclinical efficacy of the p70S6K/AKT dual inhibitor M2698 in combination with trastuzumab in models of gastric cancer [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 2935.

Triple-negative breast cancers (TNBC) have an aggressive phenotype with a relatively high rate of recurrence and poor overall survival. To date, there is no approved targeted therapy for TNBCs. Aurora kinases act as regulators of mammalian cell division. They are important for cell-cycle progression and are frequently overexpressed or mutated in human tumors, including breast cancer. In this study, we investigated the therapeutic potential of targeting Aurora kinases in preclinical models of human breast cancers using a pan-inhibitor of Aurora kinases, AS703569. In vitro, AS703569 was tested in 15 human breast cancer cell lines. TNBC cell lines were more sensitive to AS703569 than were other types of breast cancer cells. Inhibition of proliferation was associated with cell-cycle arrest, aneuploidy, and apoptosis. In vivo, AS703569 administered alone significantly inhibited tumor growth in seven of 11 patient-derived breast cancer xenografts. Treatment with AS703569 was associated with a decrease of phospho-histone H3 expression. Finally, AS703569 combined to doxorubicin–cyclophosphamide significantly inhibited in vivo tumor recurrence, suggesting that Aurora kinase inhibitors could be used both in monotherapy and in combination settings. In conclusion, these data indicate that targeting Aurora kinases could represent a new effective approach for TNBC treatment. Mol Cancer Ther; 11(12); 2693–703. ©2012 AACR.

The PI3K pathway is involved in the regulation of cell growth, proliferation, metabolism and other functions. Aberrant signaling (PTEN loss of function, PIK3CA mutation, Akt amplification, etc.) from the PI3K pathway is observed in >50% of all tumors. Clinical evidence suggests that inhibiting the PI3K pathway is beneficial for the treatment of solid tumors and tumors of the hematopoietic system. Inhibition of mTOR via rapalogs has been shown to block a negative feedback loop, thereby leading to the activation of Akt. The activation of this Akt feedback loop has been suggested to potentially compromise the clinical efficacy of selective mTORC1 inhibitors such as temsirolimus and everolimus. Dual p70S6K/Akt inhibition may promote improved pathway inhibition and also block the negative consequences of Akt activation through the negative feedback loop. MSC2363318A is a highly selective, potent, adenosine triphosphate (ATP) competitive inhibitor of p70S6K, Akt1, and Akt3. In a cellular context, inhibition of p70S6K leads to potent inhibition of ribosomal protein S6 phosphorylation, while inhibition of Akt activity blocks the negative effects of a compensatory feedback loop. In addition, MSC2363318A exhibits potent anti-proliferative activity against many solid tumor cell lines in vitro, especially those with PI3K pathway genomic alterations. Further, MSC2363318A can also cross the blood-brain barrier (via pre-clinical studies in mice, rat, and dog), a unique characteristic that would allow for treating not only malignancies that are driven by PI3K pathway genomic alterations, but also indications with a high incidence of CNS metastases and primary malignancies of the central nervous system. Patient Derived Xenograft (PDX) models from breast cancers with a high prevalence of PI3K pathway genomic alterations; including, triple negative breast cancer and Her2+ breast cancer were evaluated. In addition, combinations with standard of care agents were then evaluated in these breast cancer PDX models. Results from these studies were correlated with PI3K pathway genomic modifications, and will be used to guide subsequent clinical studies. Citation Format: Bayard R. Huck, H Tian, Sakeena Syed, Jing Lin, Jianguo Ma, Anderson Clark, Remiguisz Kaleta, Andreas Machl, Erik Wilker, Marc Lecomte. Evaluation of p70S6K/Akt inhibitor MSC2363318A in patient derived xenograft (PDX) models of breast cancer. [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 4516. doi:10.1158/1538-7445.AM2014-4516

MSC2015103 is an orally bio-available, selective, and highly potent small molecule inhibitor of MEK1/2. As a follower to the front-runner MEK inhibitor, pimasertib (MSC1936369/AS703026), a prime objective for the program is to differentiate the two compounds. Results from previous pharmacokinetic (PK) studies of MSC2015103 and pimasertib in mice had shown that both compounds could effectively cross the blood-brain barrier, but that MSC2015103 was retained in the brain longer than pimasertib. This was further confirmed in a study examining the whole-body distribution of radio-labeled compounds in mice. It is unclear whether the differential brain PK characteristics of the two agents will be clinically significant. To begin to address this, a series of pre-clinical studies were performed. Exposure levels and concurrent target modulation in normal murine brain tissue were examined over time following administration of multiple doses of MSC2015103 and pimasertib. Notable differences in the magnitude and temporal dynamics of exposure were observed; while concentrations of pimasertib in the brain peaked ∼1 hour post-administration (with a correlative decrease in phospho-ERK of ∼90%) with a relatively rapid clearance out of the tissue, concentrations of MSC2015103 increased in the brain over time and remained relatively elevated until 24 hours post-administration (the last time point) with only marginal target modulation observed. As more dramatic inhibition of pERK has previously been observed in subcutaneous tumors in mice in the presence of the same exposure of MSC2015103, murine brain orthotopic models of glioblastoma were employed to compare the relative target modulation of MSC2015103 and pimasertib in tumor tissue within the brain compartment, as well as their potential anti-tumor effects. Data from these orthotopic studies demonstrated similar high levels of phospho-ERK inhibition for both MSC2015103 and pimasertib in glioblastoma tumor tissue, which correlated with similar anti-tumor activity in the U87 model. The PK of MSC2015103 varied considerably from pimasertib, with a higher exposure (AUC1-24h) ratio of brain tumor-to-normal brain with MSC2015103 as compared with pimasertib. In line with the PK findings, MSC2015103 inhibited phospho-ERK in brain tumors but with relatively less target modulation in normal brain tissue, whereas pimasertib showed similar inhibition of phospho-ERK in both tissues. Collectively, these findings suggest a potential improvement in the safety/therapeutic index in the brain for MSC2015103. This may translate into other tissues, such as the eye, which has a similar blood barrier, and may be important in light of ocular toxicities observed in clinical trials with other MEK inhibitors. 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 LB-456. doi:1538-7445.AM2012-LB-456