Comprehensive isotopomer analysis of glutamate and aspartate in small tissue samples

Stable isotopes are powerful tools to assess metabolism. 13C labeling is detected using nuclear magnetic resonance (NMR) spectroscopy or mass spectrometry (MS). MS has excellent sensitivity but generally cannot discriminate among different 13C positions (isotopomers), whereas NMR is less sensitive but reports some isotopomers. Here, we develop an MS method that reports all 16 aspartate and 32 glutamate isotopomers while requiring less than 1% of the sample used for NMR. This method discriminates between pathways that result in the same number of 13C labels in aspartate and glutamate, providing enhanced specificity over conventional MS. We demonstrate regional metabolic heterogeneity within human tumors, document the impact of fumarate hydratase (FH) deficiency in human renal cancers, and investigate the contributions of tricarboxylic acid (TCA) cycle turnover and CO2 recycling to isotope labeling in vivo. This method can accompany NMR or standard MS to provide outstanding sensitivity in isotope-labeling experiments, particularly in vivo.

Adipocytes reprogram cancer cell metabolism by diverting glucose towards glycerol-3-phosphate thereby promoting metastasis

In the tumor microenvironment, adipocytes function as an alternate fuel source for cancer cells. However, whether adipocytes influence macromolecular biosynthesis in cancer cells is unknown. Here we systematically characterized the bidirectional interaction between primary human adipocytes and ovarian cancer (OvCa) cells using multi-platform metabolomics, imaging mass spectrometry, isotope tracing and gene expression analysis. We report that, in OvCa cells co-cultured with adipocytes and in metastatic tumors, a part of the glucose from glycolysis is utilized for the biosynthesis of glycerol-3-phosphate (G3P). Normoxic HIF1α protein regulates the altered flow of glucose-derived carbons in cancer cells, resulting in increased glycerophospholipids and triacylglycerol synthesis. The knockdown of HIF1α or G3P acyltransferase 3 (a regulatory enzyme of glycerophospholipid synthesis) reduced metastasis in xenograft models of OvCa. In summary, we show that, in an adipose-rich tumor microenvironment, cancer cells generate G3P as a precursor for critical membrane and signaling components, thereby promoting metastasis. Targeting biosynthetic processes specific to adipose-rich tumor microenvironments might be an effective strategy against metastasis.

Reporting on FH-deficient renal cell carcinoma using circulating succinylated metabolites

Fumarate hydratase-deficient (FH-deficient) renal cell carcinoma (RCC) represents a particularly aggressive form of kidney cancer. FH-deficient RCC arises in the setting of germline, or solely somatic, mutations in the FH gene, a two-hit tumor suppressor gene. Early detection can be curative, but there are no biomarkers, and in the sporadic setting, establishing a diagnosis of FH-deficient RCC is challenging. In this issue of the JCI, Zheng, Zhu, and co-authors report untargeted plasma metabolomic analyses to identify putative biomarkers. They discovered two plasma metabolites directly linked to fumarate overproduction by tumor cells, succinyl-adenosine and succinic-cysteine, which correlate with tumor burden. The identification of circulating biomarkers of FH-deficient RCC may aid in the diagnosis of FH-deficient RCC and provide a means for longitudinal follow-up.

Electron transport chain inhibition increases cellular dependence on purine transport and salvage

Cancer cells reprogram their metabolism to support cell growth and proliferation in harsh environments. While many studies have documented the importance of mitochondrial oxidative phosphorylation (OXPHOS) in tumor growth, some cancer cells experience conditions of reduced OXPHOS in vivo and induce alternative metabolic pathways to compensate. To assess how human cells respond to mitochondrial dysfunction, we performed metabolomics in fibroblasts and plasma from patients with inborn errors of mitochondrial metabolism, and in cancer cells subjected to inhibition of the electron transport chain (ETC). All these analyses revealed extensive perturbations in purine-related metabolites; in non-small cell lung cancer (NSCLC) cells, ETC blockade led to purine metabolite accumulation arising from a reduced cytosolic NAD ⁺ /NADH ratio (NADH reductive stress). Stable isotope tracing demonstrated that ETC deficiency suppressed de novo purine nucleotide synthesis while enhancing purine salvage. Analysis of NSCLC patients infused with [U- ¹³ C]glucose revealed that tumors with markers of low oxidative mitochondrial metabolism exhibited high expression of the purine salvage enzyme HPRT1 and abundant levels of the HPRT1 product inosine monophosphate (IMP). ETC blockade also induced production of ribose-5' phosphate (R5P) by the pentose phosphate pathway (PPP) and import of purine nucleobases. Blocking either HPRT1 or nucleoside transporters sensitized cancer cells to ETC inhibition, and overexpressing nucleoside transporters was sufficient to drive growth of NSCLC xenografts. Collectively, this study mechanistically delineates how cells compensate for suppressed purine metabolism in response to ETC blockade, and uncovers a new metabolic vulnerability in tumors experiencing NADH excess.

Mitochondrial metabolism in primary and metastatic human kidney cancers

Most kidney cancers display evidence of metabolic dysfunction1-4 but how this relates to cancer progression in humans is unknown. We used a multidisciplinary approach to infuse 13C-labeled nutrients during surgical tumour resection in over 70 patients with kidney cancer. Labeling from [U-13C]glucose varies across cancer subtypes, indicating that the kidney environment alone cannot account for all metabolic reprogramming in these tumours. Compared to the adjacent kidney, clear cell renal cell carcinomas (ccRCC) display suppressed labelling of tricarboxylic acid (TCA) cycle intermediates in vivo and in organotypic slices cultured ex vivo, indicating that suppressed labeling is tissue intrinsic. Infusions of [1,2-13C]acetate and [U-13C]glutamine in patients, coupled with respiratory flux of mitochondria isolated from kidney and tumour tissue, reveal primary defects in mitochondrial function in human ccRCC. However, ccRCC metastases unexpectedly have enhanced labeling of TCA cycle intermediates compared to primary ccRCCs, indicating a divergent metabolic program during ccRCC metastasis in patients. In mice, stimulating respiration in ccRCC cells is sufficient to promote metastatic colonization. Altogether, these findings indicate that metabolic properties evolve during human kidney cancer progression, and suggest that mitochondrial respiration may be limiting for ccRCC metastasis but not for ccRCC growth at the site of origin.

TAMI-05. FATTY ACID SYNTHESIS IS REQUIRED FOR HER2+ BREAST CANCER BRAIN METASTASIS

Brain metastases are refractory to therapies that control systemic disease in patients with human epidermal growth factor receptor 2-positive breast cancer and the brain microenvironment contributes to this therapy resistance. Nutrient availability can vary across tissues, therefore metabolic adaptations required for brain metastatic breast cancer growth may introduce liabilities that can be exploited for therapy. Here we assessed how metabolism differs between breast tumors in brain versus extracranial sites and found that fatty acid synthesis is elevated in breast tumors growing in the brain. We determine that this phenotype is an adaptation to decreased lipid availability in the brain relative to other tissues, resulting in site-specific dependency on fatty acid synthesis for breast tumors growing at this site. Genetic or pharmacological inhibition of fatty acid synthase reduces human epidermal growth factor receptor 2-positive breast tumor growth in the brain, demonstrating that differences in nutrient availability across metastatic sites can result in targetable metabolic dependencies.

Abstract 90: Fatty acid synthesis is required for breast cancer brain metastasis

Brain metastases are refractory to therapies that otherwise control systemic disease in patients with human epidermal growth factor receptor 2 (HER2+) breast cancer, and the unique brain microenvironment contributes to this therapy resistance. Nutrient availability can vary across tissues, therefore metabolic adaptations required for breast cancer growth in the brain microenvironment may also introduce liabilities that can be exploited for therapy. Here, we assessed how metabolism differs between breast tumors growing in the brain versus extracranial sites and found that fatty acid synthesis is elevated in breast tumors growing in the brain. We determine that this phenotype is an adaptation to decreased lipid availability in the brain relative to other tissues, which results in a site-specific dependency on fatty acid synthesis for breast tumors growing at this site. Genetic or pharmacological inhibition of fatty acid synthase (FASN) reduces HER2+ breast tumor growth in the brain, demonstrating that differences in nutrient availability across metastatic sites can result in targetable metabolic dependencies.

Citation Format: Gino B. Ferraro, Ahmed Ali, Alba Luengo, David P. Kodack, Amy Deik, Keene L. Abbott, Divya Bezwada, Landry Blanc, Brendan Prideaux, Xin Jin, Jessica M. Possada, Jiang Chen, Christopher R. Chin, Zohreh Amoozgar, Raphael Ferreira, Ivy Chen, Kamila Naxerova, Christopher Ng, Anna M. Westermark, Mark Duquette, Sylvie Roberge, Costas A. Lyssiotis, Dan G. Duda, Todd R. Golub, Shawn M. Davidson, Dai Fukumura, Véronique A. Dartois, Clary B. Clish, Matthew G. Vander Heiden, Rakesh K. Jain. Fatty acid synthesis is required for breast cancer brain metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 90.

Mitochondrial NADP+ is essential for proline biosynthesis during cell growth

Nicotinamide adenine dinucleotide phosphate (NADP⁺) is vital to produce NADPH, a principal supplier of reducing power for biosynthesis of macromolecules and protection against oxidative stress. NADPH exists in separate pools, in both the cytosol and mitochondria; however, the cellular functions of mitochondrial NADPH are incompletely described. Here, we find that decreasing mitochondrial NADP(H) levels through depletion of NAD kinase 2 (NADK2), an enzyme responsible for production of mitochondrial NADP⁺, renders cells uniquely proline auxotrophic. Cells with NADK2 deletion fail to synthesize proline, due to mitochondrial NADPH deficiency. We uncover the requirement of mitochondrial NADPH and NADK2 activity for the generation of the pyrroline-5-carboxylate metabolite intermediate as the bottleneck step in the proline biosynthesis pathway. Notably, after NADK2 deletion, proline is required to support nucleotide and protein synthesis, making proline essential for the growth and proliferation of NADK2-deficient cells. Thus, we highlight proline auxotrophy in mammalian cells and discover that mitochondrial NADPH is essential to enable proline biosynthesis.

FATTY ACID SYNTHESIS IS REQUIRED FOR BREAST CANCER BRAIN METASTASIS

Brain metastases are refractory to therapies that control systemic disease in patients with human epidermal growth factor receptor 2 (HER2+) breast cancer, and the brain microenvironment contributes to this therapy resistance. Nutrient availability can vary across tissues, therefore metabolic adaptations required for brain metastatic breast cancer growth may introduce liabilities that can be exploited for therapy. Here, we assessed how metabolism differs between breast tumors in brain versus extracranial sites and found that fatty acid synthesis is elevated in breast tumors growing in brain. We determine that this phenotype is an adaptation to decreased lipid availability in brain relative to other tissues, resulting in a site-specific dependency on fatty acid synthesis for breast tumors growing at this site. Genetic or pharmacological inhibition of fatty acid synthase (FASN) reduces HER2+ breast tumor growth in the brain, demonstrating that differences in nutrient availability across metastatic sites can result in targetable metabolic dependencies.

DDRE-07. FATTY ACID SYNTHESIS IS REQUIRED FOR BREAST CANCER BRAIN METASTASIS

Brain metastases are refractory to therapies that otherwise control systemic disease in patients with human epidermal growth factor receptor 2 (HER2+) breast cancer, and the unique brain microenvironment contributes to this therapy resistance. Nutrient availability can vary across tissues, therefore metabolic adaptations required for breast cancer growth in the brain microenvironment may also introduce liabilities that can be exploited for therapy. Here, we assessed how metabolism differs between breast tumors growing in the brain versus extracranial sites and found that fatty acid synthesis is elevated in breast tumors growing in the brain. We determine that this phenotype is an adaptation to decreased lipid availability in the brain relative to other tissues, which results in a site-specific dependency on fatty acid synthesis for breast tumors growing at this site. Genetic or pharmacological inhibition of fatty acid synthase (FASN) reduces HER2+ breast tumor growth in the brain, demonstrating that differences in nutrient availability across metastatic sites can result in targetable metabolic dependencies.

TRPML1 Promotes Protein Homeostasis in Melanoma Cells by Negatively Regulating MAPK and mTORC1 Signaling

We screen ion channels and transporters throughout the genome to identify those required by human melanoma cells but not by normal human melanocytes. We discover that Mucolipin-1 (MCOLN1), which encodes the lysosomal cation channel TRPML1, is preferentially required for the survival and proliferation of melanoma cells. Loss of MCOLN1/TRPML1 function impairs the growth of patient-derived melanomas in culture and in xenografts but does not affect the growth of human melanocytes. TRPML1 expression and macropinocytosis are elevated in melanoma cells relative to melanocytes. TRPML1 is required in melanoma cells to negatively regulate MAPK pathway and mTORC1 signaling. TRPML1-deficient melanoma cells exhibit decreased survival, proliferation, tumor growth, and macropinocytosis, as well as serine depletion and proteotoxic stress. All of these phenotypes are partially or completely rescued by mTORC1 inhibition. Melanoma cells thus increase TRPML1 expression relative to melanocytes to attenuate MAPK and mTORC1 signaling, to sustain macropinocytosis, and to avoid proteotoxic stress.

Isotope Tracing of Human Clear Cell Renal Cell Carcinomas Demonstrates Suppressed Glucose Oxidation In Vivo

Clear cell renal cell carcinoma (ccRCC) is the most common form of human kidney cancer. Histological and molecular analyses suggest that ccRCCs have significantly altered metabolism. Recent human studies of lung cancer and intracranial malignancies demonstrated an unexpected preservation of carbohydrate oxidation in the tricarboxylic acid (TCA) cycle. To test the capacity of ccRCC to oxidize substrates in the TCA cycle, we infused 13C-labeled fuels in ccRCC patients and compared labeling patterns in tumors and adjacent kidney. After infusion with [U-13C]glucose, ccRCCs displayed enhanced glycolytic intermediate labeling, suppressed pyruvate dehydrogenase flow, and reduced TCA cycle labeling, consistent with the Warburg effect. Comparing 13C labeling among ccRCC, brain, and lung tumors revealed striking differences. Primary ccRCC tumors demonstrated the highest enrichment in glycolytic intermediates and lowest enrichment in TCA cycle intermediates. Among human tumors analyzed by intraoperative 13C infusions, ccRCC is the first to demonstrate a convincing shift toward glycolytic metabolism.

Abstract LB-057: Hypoxia regulation of antigen presentation machinery expression in breast cancer

Antigen presentation plays a major role in tumor cell recognition and targeting by immune cells, and is critical to the success of many cancer immunotherapies. How the abnormal tumor microenvironment affects tumor cell antigen presentation is unclear. Hypoxia is a prevalent feature of the tumor microenvironment. Here, we showed that the expression of major histocompatibility complex class I (MHCI) is associated with regions of hypoxia in human breast tumors. The association between hypoxia and MHCI is independent of the breast tumor hormone receptor and HER2 expression status. In vitro studies revealed that hypoxia directly regulates the expression levels of MHCI along with other components of the antigen presentation machinery. Multiple kinase regulators of MHCI expression are responsive to hypoxia. These results suggest that hypoxia effects on cancer cell antigen presentation may be a potential mechanism of tumor immune evasion and treatment resistance.

Citation Format: Mei Rosa Ng, Francesco Sabbatino, Mark Duquette, Kamila Naxerova, Mark Badeaux, Gino B. Ferraro, Shan M. Chin, Divya Bezwada, Elena F. Brachtel, Soldano Ferrone, Rakesh K. Jain. Hypoxia regulation of antigen presentation machinery expression in breast 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 LB-057.

The brain microenvironment mediates resistance in luminal breast cancer to PI3K inhibition through HER3 activation

Although targeted therapies are often effective systemically, they fail to adequately control brain metastases. In preclinical models of breast cancer that faithfully recapitulate the disparate clinical responses in these microenvironments, we observed that brain metastases evade phosphatidylinositide 3-kinase (PI3K) inhibition despite drug accumulation in the brain lesions. In comparison to extracranial disease, we observed increased HER3 expression and phosphorylation in brain lesions. HER3 blockade overcame the resistance of HER2-amplified and/or PIK3CA-mutant breast cancer brain metastases to PI3K inhibitors, resulting in marked tumor growth delay and improvement in mouse survival. These data provide a mechanistic basis for therapeutic resistance in the brain microenvironment and identify translatable treatment strategies for HER2-amplified and/or PIK3CA-mutant breast cancer brain metastases.

Abstract 5008: The brain microenvironment mediates resistance in luminal breast cancer to PI3K inhibition through HER3 activation

Brain metastases represent a devastating progression of luminal breast cancer. While targeted therapies are often effective systemically, they fail to adequately control brain metastases. In preclinical models that faithfully recapitulate the disparate clinical responses in these microenvironments, we observed that brain metastases evade PI3K inhibition despite efficient drug delivery. In comparison to extracranial disease, there is increased HER3 expression and phosphorylation in the brain lesions. HER3 blockade overcomes the resistance of both HER2-amplified and/or PIK3CA-mutant breast cancer brain metastases to PI3K inhibitors, leading to striking tumor growth delay and significant improvement of mouse survival. Collectively, these data provide a mechanistic basis underlying therapeutic resistance in the brain microenvironment and identify rapidly translatable treatment strategiesfor HER2-amplified and/or PIK3CA-mutant breast cancer brain metastases.

Citation Format: Gino B. Ferraro, David P. Kodack, Vasileios Askoxylakis, Qing Sheng, Mark Badeaux, Shom Goel, Xiaolong Qi, Ram Shankaraiah, Alexander Z. Cao, Rakesh R. Ramjiawan, Divya Bezwada, Bhushankumar Patel, Youngchul Song, Carlotta Costa, Kamila Naxerova, Christina Wong, Jonas Kloepper, Rita Das, Angela Tam, Jantima Tanboon, Dan G. Duda, Ryan C. Miller, Marni B. Siegel, Carey K. Anders, Melinda Sanders, Valeria M. Estrada, Robert Schlegel, Carlos L. Arteaga, Elena Brachtel, Alan Huang, Dai Fukumura, Jeffrey A. Engelman, Rakesh K. Jain. The brain microenvironment mediates resistance in luminal breast cancer to PI3K inhibition through HER3 activation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5008. doi:10.1158/1538-7445.AM2017-5008

CPS1 maintains pyrimidine pools and DNA synthesis in KRAS/LKB1-mutant lung cancer cells

Metabolic reprogramming by oncogenic signals promotes cancer initiation and progression. The oncogene KRAS and tumour suppressor STK11, which encodes the kinase LKB1, regulate metabolism and are frequently mutated in non-small-cell lung cancer (NSCLC). Concurrent occurrence of oncogenic KRAS and loss of LKB1 (KL) in cells specifies aggressive oncological behaviour. Here we show that human KL cells and tumours share metabolomic signatures of perturbed nitrogen handling. KL cells express the urea cycle enzyme carbamoyl phosphate synthetase-1 (CPS1), which produces carbamoyl phosphate in the mitochondria from ammonia and bicarbonate, initiating nitrogen disposal. Transcription of CPS1 is suppressed by LKB1 through AMPK, and CPS1 expression correlates inversely with LKB1 in human NSCLC. Silencing CPS1 in KL cells induces cell death and reduces tumour growth. Notably, cell death results from pyrimidine depletion rather than ammonia toxicity, as CPS1 enables an unconventional pathway of nitrogen flow from ammonia into pyrimidines. CPS1 loss reduces the pyrimidine to purine ratio, compromises S-phase progression and induces DNA-polymerase stalling and DNA damage. Exogenous pyrimidines reverse DNA damage and rescue growth. The data indicate that the KL oncological genotype imposes a metabolic vulnerability related to a dependence on a cross-compartmental pathway of pyrimidine metabolism in an aggressive subset of NSCLC.

Preclinical Efficacy of Ado-trastuzumab Emtansine in the Brain Microenvironment

BACKGROUND

Central nervous system (CNS) metastases represent a major problem in the treatment of human epidermal growth factor receptor 2 (HER2)-positive breast cancer because of the disappointing efficacy of HER2-targeted therapies against brain lesions. The antibody-drug conjugate ado-trastuzumab emtansine (T-DM1) has shown efficacy in trastuzumab-resistant systemic breast cancer. Here, we tested the hypothesis that T-DM1 could overcome trastuzumab resistance in murine models of brain metastases.

METHODS

We treated female nude mice bearing BT474 or MDA-MB-361 brain metastases (n = 9-11 per group) or cancer cells grown in organotypic brain slice cultures with trastuzumab or T-DM1 at equivalent or equipotent doses. Using intravital imaging, molecular techniques and histological analysis we determined tumor growth, mouse survival, cancer cell apoptosis and proliferation, tumor drug distribution, and HER2 signaling. Data were analyzed with one-way analysis of variance (ANOVA), Kaplan-Meier analysis, and Coefficient of Determination. All statistical tests were two-sided.

RESULTS

T-DM1 delayed the growth of HER2-positive breast cancer brain metastases compared with trastuzumab. These findings were consistent between HER2-driven and PI3K-driven tumors. The activity of T-DM1 resulted in a survival benefit (median survival for BT474 tumors: 28 days for trastuzumab vs 112 days for T-DM1, hazard ratio = 6.2, 95% confidence interval = 6.1 to 85.84, P < .001). No difference in drug distribution or HER2-signaling was revealed between the two groups. However, T-DM1 led to a statistically significant increase in tumor cell apoptosis (one-way ANOVA for ApopTag, P < .001), which was associated with mitotic catastrophe.

CONCLUSIONS

T-DM1 can overcome resistance to trastuzumab therapy in HER2-driven or PI3K-driven breast cancer brain lesions due to the cytotoxicity of the DM1 component. Clinical investigation of T-DM1 for patients with CNS metastases from HER2-positive breast cancer is warranted.

Abstract 130: PF-06463922, a novel next generation ALK/ROS1 inhibitor, overcomes resistance to 1st and 2nd generation ALK inhibitors in pre-clinical models

Overcoming resistance to targeted kinase inhibitors is a major clinical challenge in oncology.

For 1st and 2nd generation ALK inhibitors acquired resistance due to ALK kinase domain mutations and/or pharmacological drug resistance are major causes for disease relapse. Here, we report the preclinical evaluation of PF-06463922, a potent and brain penetrant ALK/ROS1 inhibitor with sub to low nanomolar cell potency against ALK fusions and all known clinically-acquired resistant mutations. PF-06463922 exhibited marked cytoreductive activity in tumor xenografts driven by various ALK mutants. Furthermore, PF-06463922 led to significant regression of EML4-ALK driven lung cancer brain metastasis and prolonged mouse survival. Compared to other clinically available ALK inhibitors, PF-06463922 is unique in its superior potency against a broad spectrum of acquired ALK mutations, including the highly resistant G1202R mutant and its robust antitumor activity in the brain. Furthermore, PF-06463922 demonstrated remarkable selectivity and safety margins in a variety of preclinical studies. These results suggest that PF-06463922 may be highly effective for the treatment of patients with ALK-driven lung cancers, including those who relapsed on clinically available ALK inhibitors due to ALK secondary mutations and/or brain metastases.

Citation Format: Luc Friboulet, Helen Zou, David P. Kodack, Lars D. Engstrom, Qiuhua Li, Melissa West, Ruth W. Tang, Hui Wang, Konstantinos Tsaparikos, Jinwei Wang, Sergei Timofeevski, Dac M. Dinh, Hieu Lam, Justine L. Lam, Shinji Yamazaki, Wenyue Hu, Bhushankumar Patel, Divya Bezwada, Sidra Mahmood, Eugene Lifshits, Timothy Affolter, Patrick B. Lappin, Hovhannes Gukasyan, Nathan Lee, Shibing Deng, Rakesh K. Jain, Ted W. Johnson, Alice T. Shaw, Valeria R. Fantin, Tod Smeal. PF-06463922, a novel next generation ALK/ROS1 inhibitor, overcomes resistance to 1st and 2nd generation ALK inhibitors in pre-clinical models. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 130. doi:10.1158/1538-7445.AM2015-130

PF-06463922, an ALK/ROS1 Inhibitor, Overcomes Resistance to First and Second Generation ALK Inhibitors in Preclinical Models

We report the preclinical evaluation of PF-06463922, a potent and brain-penetrant ALK/ROS1 inhibitor. Compared with other clinically available ALK inhibitors, PF-06463922 displayed superior potency against all known clinically acquired ALK mutations, including the highly resistant G1202R mutant. Furthermore, PF-06463922 treatment led to regression of EML4-ALK-driven brain metastases, leading to prolonged mouse survival, in a superior manner. Finally, PF-06463922 demonstrated high selectivity and safety margins in a variety of preclinical studies. These results suggest that PF-06463922 will be highly effective for the treatment of patients with ALK-driven lung cancers, including those who relapsed on clinically available ALK inhibitors because of secondary ALK kinase domain mutations and/or brain metastases.