Convergent loss of PTEN leads to clinical resistance to a PI(3)Kα inhibitor.

Broad and deep tumour genome sequencing has shed new light on tumour heterogeneity and provided important insights into the evolution of metastases arising from different clones. There is an additional layer of complexity, in that tumour evolution may be influenced by selective pressure provided by therapy, in a similar fashion to that occurring in infectious diseases. Here we studied tumour genomic evolution in a patient (index patient) with metastatic breast cancer bearing an activating PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha, PI(3)Kα) mutation. The patient was treated with the PI(3)Kα inhibitor BYL719, which achieved a lasting clinical response, but the patient eventually became resistant to this drug (emergence of lung metastases) and died shortly thereafter. A rapid autopsy was performed and material from a total of 14 metastatic sites was collected and sequenced. All metastatic lesions, when compared to the pre-treatment tumour, had a copy loss of PTEN (phosphatase and tensin homolog) and those lesions that became refractory to BYL719 had additional and different PTEN genetic alterations, resulting in the loss of PTEN expression. To put these results in context, we examined six other patients also treated with BYL719. Acquired bi-allelic loss of PTEN was found in one of these patients, whereas in two others PIK3CA mutations present in the primary tumour were no longer detected at the time of progression. To characterize our findings functionally, we examined the effects of PTEN knockdown in several preclinical models (both in cell lines intrinsically sensitive to BYL719 and in PTEN-null xenografts derived from our index patient), which we found resulted in resistance to BYL719, whereas simultaneous PI(3)K p110ß blockade reverted this resistance phenotype. We conclude that parallel genetic evolution of separate metastatic sites with different PTEN genomic alterations leads to a convergent PTEN-null phenotype resistant to PI(3)Kα inhibition.

MEK162 for patients with advanced melanoma harbouring NRAS or Val600 BRAF mutations: a non-randomised, open-label phase 2 study.

BACKGROUND: Patients with melanoma harbouring Val600 BRAF mutations benefit from treatment with BRAF inhibitors. However, no targeted treatments exist for patients with BRAF wild-type tumours, including those with NRAS mutations. We aimed to assess the use of MEK162, a small-molecule MEK1/2 inhibitor, in patients with NRAS-mutated or Val600 BRAF-mutated advanced melanoma. METHODS: In our open-label, non-randomised, phase 2 study, we assigned patients with NRAS-mutated or BRAF-mutated advanced melanoma to one of three treatment arms on the basis of mutation status. Patients were enrolled at university hospitals or private cancer centres in Europe and the USA. The three arms were: twice-daily MEK162 45 mg for NRAS-mutated melanoma, twice-daily MEK162 45 mg for BRAF-mutated melanoma, and twice-daily MEK162 60 mg for BRAF-mutated melanoma. Previous treatment with BRAF inhibitors was permitted, but previous MEK inhibitor therapy was not allowed. The primary endpoint was the proportion of patients who had an objective response (ie, a complete response or confirmed partial response). We report data for the 45 mg groups. We assessed clinical activity in all patients who received at least one dose of MEK162 and in patients assessable for response (with two available CT scans). This study is registered with ClinicalTrials.gov, number NCT01320085, and is currently recruiting additional patients with NRAS mutations (based on a protocol amendment). FINDINGS: Between March 31, 2011, and Jan 17, 2012, we enrolled 71 patients who received at least one dose of MEK162 45 mg. By Feb 29, 2012 (data cutoff), median follow-up was 3·3 months (range 0·6-8·7; IQR 2·2-5·0). No patients had a complete response. Six (20%) of 30 patients with NRAS-mutated melanoma had a partial response (three confirmed) as did eight (20%) of 41 patients with BRAF-mutated melanoma (two confirmed). The most frequent adverse events were acneiform dermatitis (18 [60%] patients with NRAS -mutated melanoma and 15 [37%] patients with the BRAF-mutated melanoma), rash (six [20%] and 16 [39%]), peripheral oedema (ten [33%] and 14 [34%]), facial oedema (nine [30%] and seven [17%]), diarrhoea (eight [27%] and 15 [37%]), and creatine phosphokinase increases (11 [37%] and nine [22%]). Increased creatine phosphokinase was the most common grade 3-4 adverse event (seven [23%] and seven [17%]). Four patients had serious adverse events (two per arm), which included diarrhoea, dehydration, acneiform dermatitis, general physical deterioration, irregular heart rate, malaise, and small intestinal perforation. No deaths occurred from treatment-related causes. INTERPRETATION: To our knowledge, MEK162 is the first targeted therapy to show activity in patients with NRAS -mutated melanoma and might offer a new option for a cancer with few effective treatments. FUNDING: Novartis Pharmaceuticals.

DJ-1, a novel regulator of the tumor suppressor PTEN.

The phosphatidylinositol 3' kinase (PI3'K) pathway, which regulates cell survival, is antagonized by the PTEN tumor suppressor. The regulation of PTEN is unclear. A genetic screen of Drosophila gain-of-function mutants identified DJ-1 as a suppressor of PTEN function. In mammalian cells, DJ-1 underexpression results in decreased phosphorylation of PKB/Akt, while DJ-1 overexpression leads to hyperphosphorylation of PKB/Akt and increased cell survival. In primary breast cancer samples, DJ-1 expression correlates negatively with PTEN immunoreactivity and positively with PKB/Akt hyperphosphorylation. In 19/23 primary non-small cell lung carcinoma samples, DJ-1 expression was increased compared to paired nonneoplastic lung tissue, and correlated positively with relapse incidence. DJ-1 is thus a key negative regulator of PTEN that may be a useful prognostic marker for cancer.

Optimizing the Therapeutic Window of Targeted Drugs in Oncology: Potency-Guided First-in-Human Studies.

Many targeted therapies are administered at or near the maximum tolerated dose (MTD). With the advent of precision medicine, a larger therapeutic window is expected. Therefore, dose optimization will require a new approach to early clinical trial design. We analyzed publicly available data for 21 therapies targeting six kinases, and four poly (ADP-ribose) polymerase inhibitors, focusing on potency and exposure to gain insight into dose selection. The free average steady-state concentration (Css ) at the approved dose was compared to the in vitro cell potency (half-maximal inhibitory concentration (IC50 )). Average steady-state area under the plasma concentration-time curve, the fraction unbound drug in plasma, and the cell potency were taken from the US drug labels, US and European regulatory reviews, and peer-reviewed journal articles. The Css was remarkably similar to the IC50 . The median Css /IC50 value was 1.2, and 76% of the values were within 3-fold of unity. However, three drugs (encorafenib, erlotinib, and ribociclib) had a Css /IC50 value > 25. Seven other therapies targeting the same 3 kinases had much lower Css /IC50 values ranging from 0.5 to 4. These data suggest that these kinase inhibitors have a large therapeutic window that is not fully exploited; lower doses may be similarly efficacious with improved tolerability. We propose a revised first-in-human trial design in which dose cohort expansion is initiated at doses less than the MTD when there is evidence of clinical activity and Css exceeds a potency threshold. This potency-guided approach is expected to maximize the therapeutic window thereby improving patient outcomes.

Serum concentrations of DKK-1 correlate with the extent of bone disease in patients with multiple myeloma.

OBJECTIVES: Lytic bone disease is a hallmark of multiple myeloma (MM) and is caused by osteoclast activation and osteoblast inhibition. Secretion of Dickkopf (DKK)-1 by myeloma cells is a major factor which causes inhibition of osteoblast precursors. So far, there is no study showing a significant difference in serum DKK-1 levels in MM patients with or without lytic bone lesions. METHODS: DKK-1 serum levels were quantified in 184 untreated MM patients and 33 monoclonal gammopathy of undetermined significance (MGUS) patients by ELISA, using a monoclonal anti-DKK-1 antibody. RESULTS: Serum DKK-1 was elevated in MM as compared with MGUS (mean 11 963 pg/mL vs. 1993 pg/mL; P < 0.05). Serum DKK-1 levels significantly correlated with myeloma stage according to Durie and Salmon (mean 2223 pg/mL vs. 15 209 pg/mL in stage I and II/III, respectively; P = 0.005). Importantly, myeloma patients without lytic lesions in conventional radiography had significantly lower DKK-1 levels than patients with lytic bone disease (mean 3114 pg/mL vs. 17 915 pg/mL; P = 0.003). Of interest, serum DKK-1 correlated with the number of bone lesions (0 vs. 1-3 vs. >3 lesions: 3114 pg/mL vs. 3559 pg/mL vs. 24 068 pg/mL; P = 0.002). CONCLUSION: Using a large series of myeloma patients, we could show for the first time a correlation between DKK-1 serum concentration and the amount of lytic bone disease, indicating that DKK-1 is an important factor for the extent of bone disease and supporting the hypothesis of DKK-1 as a therapeutic target in myeloma bone disease.

Preclinical Therapeutic Synergy of MEK1/2 and CDK4/6 Inhibition in Neuroblastoma.

Purpose: Neuroblastoma is treated with aggressive multimodal therapy, yet more than 50% of patients experience relapse. We recently showed that relapsed neuroblastomas frequently harbor mutations leading to hyperactivated ERK signaling and sensitivity to MEK inhibition therapy. Here we sought to define a synergistic therapeutic partner to potentiate MEK inhibition.Experimental Design: We first surveyed 22 genetically annotated human neuroblastoma-derived cell lines (from 20 unique patients) for sensitivity to the MEK inhibitor binimetinib. After noting an inverse correlation with sensitivity to ribociclib (CDK4/6 inhibitor), we studied the combinatorial effect of these two agents using proliferation assays, cell-cycle analysis, Ki67 immunostaining, time-lapse microscopy, and xenograft studies.Results: Sensitivity to binimetinib and ribociclib was inversely related (r = -0.58, P = 0.009). MYCN amplification status and expression were associated with ribociclib sensitivity and binimetinib resistance, whereas increased MAPK signaling was the main determinant of binimetinib sensitivity and ribociclib resistance. Treatment with both compounds resulted in synergistic or additive cellular growth inhibition in all lines tested and significant inhibition of tumor growth in three of four xenograft models of neuroblastoma. The augmented growth inhibition was attributed to diminished cell-cycle progression that was reversible upon removal of drugs.Conclusions: Here we demonstrate that combined binimetinib and ribociclib treatment shows therapeutic synergy across a broad panel of high-risk neuroblastoma preclinical models. These data support testing this combination therapy in relapsed high-risk neuroblastoma patients, with focus on cases with hyperactivated RAS-MAPK signaling. Clin Cancer Res; 23(7); 1785-96. ©2016 AACR.

Expression of epithelial cellular adhesion molecule (Ep-CAM) in chronic (necro-)inflammatory liver diseases and hepatocellular carcinoma.

Epithelial cell adhesion molecule (Ep-CAM) is expressed in a several epithelial tissues and carcinomas, but not on mature hepatocytes. Here, we analysed the expression of Ep-CAM in 230 patients suffering from various liver diseases like chronic hepatitis B and C (HBV and HCV infection), chronic autoimmune hepatitis (AIH), chronic alcoholic liver disease (ALD), primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC), hereditary hemochromatosis and dysplastic nodules (DNs) as well as hepatocellular carcinomas (HCCs) and cholangiocellular carcinomas (CCCs) by immunohistochemistry. De novo hepatocellular Ep-CAM expression was found in 75.9% of ALD (22/29), 63.6% of HCV (21/33) and 55.6% of each AIH and HBV cases (5/9 and 15/27, respectively). Lower Ep-CAM expression levels were observed for primary sclerosing liver diseases (PBC and PSC) with 25% (3/12) and 7.7% (1/13) of cases. Moreover, only 14.3% of HCCs (9/63) manifested expression, while all CCCs showed strong Ep-CAM expression (5/5). For DNs and hereditary hemochromatosis, Ep-CAM expression was found in 10 and 50% (3/30 and 2/4), respectively. In HBV and HCV, Ep-CAM expression correlated significantly with inflammatory activity as assessed by histological parameters and to the extent of fibrosis. In addition, for HCV also transaminase levels correlated significantly with Ep-CAM expression. Our results indicate that de novo Ep-CAM expression in hepatocytes is frequent in inflammatory liver diseases and is potentially linked to regenerative activity. CCCs and Ep-CAM positive HCCs may represent an attractive target group for Ep-CAM-directed immunotherapies, yet unwanted toxicity may limit the use of such strategies due to Ep-CAM expression in biliary epithelium and several chronic liver diseases such as HBV-and HCV-hepatitis.

Personalized Preclinical Trials in BRAF Inhibitor-Resistant Patient-Derived Xenograft Models Identify Second-Line Combination Therapies.

PURPOSE: To test second-line personalized medicine combination therapies, based on genomic and proteomic data, in patient-derived xenograft (PDX) models. EXPERIMENTAL DESIGN: We established 12 PDXs from BRAF inhibitor-progressed melanoma patients. Following expansion, PDXs were analyzed using targeted sequencing and reverse-phase protein arrays. By using multi-arm preclinical trial designs, we identified efficacious precision medicine approaches. RESULTS: We identified alterations previously described as drivers of resistance: NRAS mutations in 3 PDXs, MAP2K1 (MEK1) mutations in 2, BRAF amplification in 4, and aberrant PTEN in 7. At the protein level, re-activation of phospho-MAPK predominated, with parallel activation of PI3K in a subset. Second-line efficacy of the pan-PI3K inhibitor BKM120 with either BRAF (encorafenib)/MEK (binimetinib) inhibitor combination or the ERK inhibitor VX-11e was confirmed in vivo Amplification of MET was observed in 3 PDX models, a higher frequency than expected and a possible novel mechanism of resistance. Importantly, MET amplification alone did not predict sensitivity to the MET inhibitor capmatinib. In contrast, capmatinib as single agent resulted in significant but transient tumor regression in a PDX with resistance to BRAF/MEK combination therapy and high pMET. The triple combination capmatinib/encorafenib/binimetinib resulted in complete and sustained tumor regression in all animals. CONCLUSIONS: Genomic and proteomic data integration identifies dual-core pathway inhibition as well as MET as combinatorial targets. These studies provide evidence for biomarker development to appropriately select personalized therapies of patients and avoid treatment failures. See related commentary by Hartsough and Aplin, p. 1550.

A phase Ib dose-escalation study of the oral pan-PI3K inhibitor buparlisib (BKM120) in combination with the oral MEK1/2 inhibitor trametinib (GSK1120212) in patients with selected advanced solid tumors.

PURPOSE: MAPK and PI3K/AKT/mTOR pathways play important roles in many tumors. In this study, safety, antitumor activity, and pharmacokinetics of buparlisib (pan class PI3K inhibitor) and trametinib (MEK inhibitor) were evaluated. EXPERIMENTAL DESIGN: This open-label, dose-finding, phase Ib study comprised dose escalation, followed by expansion part in patients with RAS- or BRAF-mutant non-small cell lung, ovarian, or pancreatic cancer. RESULTS: Of note, 113 patients were enrolled, 66 and 47 in dose-escalation and -expansion parts, respectively. MTD was established as buparlisib 70 mg + trametinib 1.5 mg daily [5/15, 33% patients with dose-limiting toxicities (DLT)] and recommended phase II dose (RP2D) buparlisib 60 mg + trametinib 1.5 mg daily (1/10, 10% patients with DLTs). DLTs included stomatitis (8/103, 8%), diarrhea, dysphagia, and creatine kinase (CK) increase (2/103, 2% each). Treatment-related grade 3/4 adverse events (AEs) occurred in 73 patients (65%); mainly CK increase, stomatitis, AST/ALT (aspartate aminotransferase/alanine aminotransferase) increase, and rash. For all (21) patients with ovarian cancer, overall response rate was 29% [1 complete response, 5 partial responses (PR)], disease control rate 76%, and median progression-free survival was 7 months. Minimal activity was observed in patients with non-small cell lung cancer (1/17 PR) and pancreatic cancer (best overall response was SD). Relative to historical data, buparlisib exposure increased and trametinib exposure slightly increased with the combination. CONCLUSIONS: At RP2D, buparlisib 60 mg + trametinib 1.5 mg daily shows promising antitumor activity for patients with KRAS-mutant ovarian cancer. Long-term tolerability of the combination at RP2D is challenging, due to frequent dose interruptions and reductions for toxicity.

Activation of MET via diverse exon 14 splicing alterations occurs in multiple tumor types and confers clinical sensitivity to MET inhibitors.

UNLABELLED: Focal amplification and activating point mutation of the MET gene are well-characterized oncogenic drivers that confer susceptibility to targeted MET inhibitors. Recurrent somatic splice site alterations at MET exon 14 (METex14) that result in exon skipping and MET activation have been characterized, but their full diversity and prevalence across tumor types are unknown. Here, we report analysis of tumor genomic profiles from 38,028 patients to identify 221 cases with METex14 mutations (0.6%), including 126 distinct sequence variants. METex14 mutations are detected most frequently in lung adenocarcinoma (3%), but also frequently in other lung neoplasms (2.3%), brain glioma (0.4%), and tumors of unknown primary origin (0.4%). Further in vitro studies demonstrate sensitivity to MET inhibitors in cells harboring METex14 alterations. We also report three new patient cases with METex14 alterations in lung or histiocytic sarcoma tumors that showed durable response to two different MET-targeted therapies. The diversity of METex14 mutations indicates that diagnostic testing via comprehensive genomic profiling is necessary for detection in a clinical setting. SIGNIFICANCE: Here we report the identification of diverse exon 14 splice site alterations in MET that result in constitutive activity of this receptor and oncogenic transformation in vitro. Patients whose tumors harbored these alterations derived meaningful clinical benefit from MET inhibitors. Collectively, these data support the role of METex14 alterations as drivers of tumorigenesis, and identify a unique subset of patients likely to derive benefit from MET inhibitors.

Phase I, dose-escalation study of BKM120, an oral pan-Class I PI3K inhibitor, in patients with advanced solid tumors.

PURPOSE: This phase I dose-escalation study investigated the maximum-tolerated dose (MTD), safety, preliminary activity, pharmacokinetics (PK), and pharmacodynamics of BKM120, a potent and highly specific oral pan-Class I PI3K inhibitor. PATIENTS AND METHODS: Thirty-five patients with advanced solid tumors received daily BKM120 12.5 to 150 mg. Dose escalation was guided by a Bayesian logistic regression model with overdose control. Assessments included archival tumor molecular status, response by Response Evaluation Criteria in Solid Tumors (RECIST), positron emission tomography tracer uptake ([(18)F]fluorodeoxyglucose positron emission tomography [FDG-PET]), fasting plasma C-peptide, and phosphorylated ribosomal protein S6 (pS6) in skin biopsies. RESULTS: Overall, treatment was well tolerated. Dose-limiting toxicities were grade 2 mood alteration (80 mg), grade 3 epigastralgia, grade 3 rash, grade 2 and grade 3 mood alteration (100 mg), and two grade 4 hyperglycemia (150 mg). The MTD was 100 mg/d. Frequent treatment-related adverse events included rash, hyperglycemia, diarrhea, anorexia, and mood alteration (37% each); nausea (31%); fatigue (26%); pruritus (23%); and mucositis (23%). BKM120 demonstrated rapid absorption, half-life of ∼40 hours, ∼three-fold steady-state accumulation, dose-proportional exposure, and moderate interpatient variability. One patient demonstrated a confirmed partial response (triple-negative breast cancer); seven patients (20%) were on study for ≥ 8 months. BKM120 demonstrated dose-dependent pharmacodynamic effects on [(18)F]FDG-PET, fasting C-peptide, fasting blood glucose, and pS6. No significant trends were seen to correlate tumor molecular alterations with clinical activity. CONCLUSION: This study demonstrates feasibility and proof-of-concept of class I PI3K inhibition in patients with advanced cancers. BKM120, at the MTD of 100 mg/d, is safe and well tolerated, with a favorable PK profile, clear evidence of target inhibition, and preliminary antitumor activity.

Chk2 regulates irradiation-induced, p53-mediated apoptosis in Drosophila.

The tumor suppressor function of p53 has been attributed to its ability to regulate apoptosis and the cell cycle. In mammals, DNA damage, aberrant growth signals, chemotherapeutic agents, and UV irradiation activate p53, a process that is regulated by several posttranslational modifications. In Drosophila melanogaster, however, the regulation modes of p53 are still unknown. Overexpression of D. melanogaster p53 (Dmp53) in the eye induced apoptosis, resulting in a small eye phenotype. This phenotype was markedly enhanced by coexpression with D. melanogaster Chk2 (DmChk2) and was almost fully rescued by coexpression with a dominant-negative (DN), kinase-dead form of DmChk2. DN DmChk2 also inhibited Dmp53-mediated apoptosis in response to DNA damage, whereas overexpression of Grapes (Grp), the Drosophila Chk1-homolog, and its DN mutant had no effect on Dmp53-induced phenotypes. DmChk2 also activated the Dmp53 transactivation activity in cultured cells. Mutagenesis of Dmp53 amino terminal Ser residues revealed that Ser-4 is critical for its responsiveness toward DmChk2. DmChk2 activates the apoptotic activity of Dmp53 and Ser-4 is required for this effect. Contrary to results in mammals, Grapes, the Drosophila Chk1-homolog, is not involved in regulating Dmp53. Chk2 may be the ancestral regulator of p53 function.