Jose Luis Manzano

The Hippo effector YAP promotes resistance to RAF- and MEK-targeted cancer therapies

Resistance to RAF- and MEK-targeted therapy is a major clinical challenge. RAF and MEK inhibitors are initially but only transiently effective in some but not all patients with BRAF gene mutation and are largely ineffective in those with RAS gene mutation because of resistance. Through a genetic screen in BRAF-mutant tumor cells, we show that the Hippo pathway effector YAP (encoded by YAP1) acts as a parallel survival input to promote resistance to RAF and MEK inhibitor therapy. Combined YAP and RAF or MEK inhibition was synthetically lethal not only in several BRAF-mutant tumor types but also in RAS-mutant tumors. Increased YAP in tumors harboring BRAF V600E was a biomarker of worse initial response to RAF and MEK inhibition in patients, establishing the clinical relevance of our findings. Our data identify YAP as a new mechanism of resistance to RAF- and MEK-targeted therapy. The findings unveil the synthetic lethality of combined suppression of YAP and RAF or MEK as a promising strategy to enhance treatment response and patient survival.

Methylation patterns and K-ras mutations in tumor and paired serum of resected non-small-cell lung cancer patients

Gene methylation and K-ras mutations were examined in tumor and paired serum DNA of 50 resected non-small-cell lung cancer patients. RASSF1A, death associated protein kinase and target of methylation-induced silencing were methylated in 17/50 (34%), 23/50 (45%) and 18/50 (35%) tumors, respectively, and in 17/50 (34%), 20/50 (40%) and 17/50 (34%) sera, respectively. Methylation in tumor and serum were closely correlated (P=0.001), but no correlation was found with survival. Twelve K-ras mutations (cysteine) were found in serum and nine mutations were found in tumor (five cysteine, one alanine, one aspartic, one arginine, and one valine). K-ras mutations in serum correlated significantly with survival (P=0.01).

Weekly regimen of irinotecan/docetaxel in previously treated non-small cell lung cancer patients and correlation with uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) polymorphism.

Purpose: Inherited variations in drug metabolizing enzymes may influence drug efficacy. This phase II study assesses the impact of second-line weekly irinotecan (CPT-11)/docetaxel in non-small cell lung cancer (NSCLC) patients, and gauges the uridine diphosphate glucuronosyl transferase (UGT1A1) polymorphism influence in toxicity and antitumor activity. Experimental Design: Fifty-one patients with NSCLC treated with at least one prior chemotherapy regimen were enrolled. Patients received irinotecan 70 mg/m2 followed by docetaxel 25 mg/m2. Both drugs were given on days 1, 8, and 15 every 28 days. UGT1A1 polymorphism were analyzed in blood samples of 47 patients. The UGT1A1 polymorphism are classified according to the number of TA repeats in the promoter region of this gene. Results: Three patients (6%) achieved a partial response and nineteen patients (37%) had stable disease. Median survival was 8 months (95% CI: 4.8–11.2) and 1-year survival 30%. Grade 3–4 hematologic toxicity was low (less than 10% of patients); 15% of patients had grade 3 asthenia and 25% of patients had grade 3/4 diarrhea. The frequency of UGT1A1 genotypes was as follows: 6/6 49%, 6/7 36%, and 7/7 15%. No differences in toxicity were observed according to UGT1A1 polymorphism. A nonsignificant improvement in time to progression (4 vs. 3 months) and median survival (11 vs. 8 months) was detected in patients with the variant alleles (6/7 and 7/7). Conclusions: This weekly irinotecan/docetaxel regimen has shown an acceptable toxicity profile while encouraging median and 1-year survival in heavily pretreated NSCLC patients. The tendency to better prognosis in patients carrying the variant genotypes 6/7 and 7/7 of UGT1A1 gene requires further validation.

Phase II study of weekly Kahalalide F in patients with advanced malignant melanoma

This phase II clinical trial evaluated the antitumour response of Kahalalide F (KF) 650 microg/m(2) given as a 1-h weekly infusion in advanced malignant melanoma patients, both untreated and those who relapsed or progressed after one line of systemic therapy. Of 24 enrolled patients (median age, 55 years; range, 28-89), 14 patients had been previously treated with chemotherapy or biological therapy. No RECIST responses occurred; five chemotherapy-naïve patients with cutaneous melanoma had disease stabilisation for > or = 3 months; median progression-free survival was 1.7 months (95% CI, 1.2-1.9 months); and median overall survival was 10.8 months (95% CI, 5.0-upper limit not reached). The most common laboratory toxicities were non-cumulative increase of transaminases (ALT/AST) and gamma-glutamyltransferase (GGT). No patients experienced leukopenia and thrombocytopenia during the study. KF was a well-tolerated and safe chemotherapy regimen. Despite a favourable safety profile, this trial was closed after the first stage because of the lack of objective response in patients with malignant melanoma.

Pharmacogenomic approach for the identification of novel determinants of acquired resistance to oxaliplatin in colorectal cancer

Oxaliplatin is a third-generation platinum agent used in colorectal cancer treatment. Oxaliplatin resistance acquisition is a complex process mainly based on alteration of genes and pathways involved in its mechanism of action. Therefore, our purpose was to perform a gene expression screening in an in vitro model to identify genes that could play a role in oxaliplatin resistance acquisition processes. Four colorectal cancer cell lines and their oxaliplatin-resistant derived sublines were compared. Microarray analysis was done using Human 19K Oligo Array Slides. RNA from cells were hybridized with a commercial RNA reference sample and labeled with both fluorochromes Cy3 and Cy5. Data were analyzed by hierarchical clustering method. Subsequently, quantitative real-time PCR (qRT-PCR) was used to corroborate microarray data, considering as positively validated those genes that showed significant differences in expression levels between groups and a correlation between microarray and qRT-PCR data. By microarray analysis, 32 candidate genes were identified. After validation process by qRT-PCR, the genes AKT1, CDK5, TRIP, GARP, RGS11, and UGCGL1 were positively validated. The 3 first genes proved to be involved in regulation of nuclear factor-κβ antiapoptotic transcription factor previously related to drug resistance, and the other 3 genes are novel finds. We have identified 6 genes related to oxaliplatin resistance acquisition. These findings are of paramount importance to understand these processes better and open new lines of study to elucidate the relevance of this pharmacogenomic approach into the clinic. [Mol Cancer Ther 2009;8(1):194–202]

A proteomic approach links decreased pyruvate kinase M2 expression to oxaliplatin resistance in patients with colorectal cancer and in human cell lines

We aimed to gain further understanding of the molecular mechanisms involved in oxaliplatin resistance in colorectal cancer by using a proteomic approach. A 5-fold oxaliplatin-resistant cell line, HTOXAR3, was compared with its parental cell line, HT29, using two-dimensional PAGE. Mass spectrometry, Western blot, and real-time quantitative PCR confirmed the down-regulation of pyruvate kinase M2 (PK-M2) in HTOXAR3 cells. In a panel of eight colorectal cancer cell lines, we found a negative correlation between oxaliplatin resistance and PK-M2 mRNA levels (Spearman r = −0.846, P = 0.008). Oxaliplatin exposure in both HT29 and HTOXAR3 led to PK-M2 mRNA up-regulation. PK-M2 mRNA levels were measured by real-time quantitative PCR in 41 tumors treated with oxaliplatin/5-fluorouracil. Tumors with the lowest PK-M2 levels attained the lowest response rates (20% versus 64.5%, P = 0.026). High PK-M2 levels were associated with high p53 levels (P = 0.032). In conclusion, the data provided clearly link PK-M2 expression and oxaliplatin resistance mechanisms and further implicate PK-M2 as a predictive marker of response in patients with oxaliplatin-treated colorectal cancer.[Mol Cancer Ther 2009;8(4):771–8]

Epigenetic activation of a cryptic TBC1D16 transcript enhances melanoma progression by targeting EGFR

Metastasis is responsible for most cancer-related deaths, and, among common tumor types, melanoma is one with great potential to metastasize. Here we study the contribution of epigenetic changes to the dissemination process by analyzing the changes that occur at the DNA methylation level between primary cancer cells and metastases. We found a hypomethylation event that reactivates a cryptic transcript of the Rab GTPase activating protein TBC1D16 (TBC1D16-47 kDa; referred to hereafter as TBC1D16-47KD) to be a characteristic feature of the metastatic cascade. This short isoform of TBC1D16 exacerbates melanoma growth and metastasis both in vitro and in vivo. By combining immunoprecipitation and mass spectrometry, we identified RAB5C as a new TBC1D16 target and showed that it regulates EGFR in melanoma cells. We also found that epigenetic reactivation of TBC1D16-47KD is associated with poor clinical outcome in melanoma, while conferring greater sensitivity to BRAF and MEK inhibitors.

Increased levels of copper efflux transporter ATP7B are associated with poor outcome in colorectal cancer patients receiving oxaliplatin-based chemotherapy.

Recently, the copper efflux transporters ATP7B and ATP7A have been implicated in the transport of and resistance to platinum drugs in breast and ovarian cancers. Because of the extensive use of oxaliplatin in colorectal cancer (CRC), we examined the expression of both transporters in tumors from CRC patients treated with oxaliplatin/5FU and sought to determine whether their expression can predict clinical outcome in these patients. ATP7B and ATP7A levels were determined by quantitative real‐time PCR in 50 primary tumors of previously untreated patients with advanced colorectal adenocarcinoma who were subsequently treated with oxaliplatin/5FU. Additionally, ATP7B protein expression was assessed by immunohistochemical staining using a tissue microarray. Patients with the lowest mRNA expression levels of ATP7B had a significantly longer time to progression (TTP) (p = 0.0009) than patients with the highest levels (12.14 months vs. 6.43 months) who also had an increased risk of progression (HR = 3.56; 95% CI, 1.6–7.9; p = 0.002). Furthermore, patients with low levels of both protein and mRNA of ATP7B derived the maximum benefit from oxaliplatin/5FU with the longest TTP as compared with patients with high levels of ATP7B protein and mRNA (14.64 months vs. 4.63 months, respectively, p = 0.01) and showed a nonsignificant trend toward a lower response rate (37.5% and 75%, respectively). In conclusion, ATP7B mRNA and protein expression in colorectal tumors is associated with clinical outcome to oxaliplatin/5FU. Prospective studies are required to evaluate the role of this marker in tailoring chemotherapy.

Tumor-Related Molecular Mechanisms of Oxaliplatin Resistance

Oxaliplatin was the first platinum drug with proven activity against colorectal tumors, becoming a standard in the management of this malignancy. It is also considered for the treatment of pancreatic and gastric cancers. However, a major reason for treatment failure still is the existence of tumor intrinsic or acquired resistance. Consequently, it is important to understand the molecular mechanisms underlying the appearance of this phenomenon to find ways of circumventing it and to improve and optimize treatments. This review will be focused on recent discoveries about oxaliplatin tumor-related resistance mechanisms, including alterations in transport, detoxification, DNA damage response and repair, cell death (apoptotic and nonapoptotic), and epigenetic mechanisms. Mol Cancer Ther; 14(8); 1767–76. ©2015 AACR.

Phase II open-label study of erlotinib in combination with gemcitabine in unresectable and/or metastatic adenocarcinoma of the pancreas: relationship between skin rash and survival (Pantar study)

BACKGROUND Skin rash is an adverse event which might be associated with longer survival in patients treated with epidermal growth factor receptor tyrosine kinase inhibitors. The aim of this nonrandomised phase II clinical trial is to prospectively evaluate the relationship between skin rash and overall survival (OS) in advanced/metastatic pancreatic cancer treated with erlotinib plus gemcitabine. PATIENTS AND METHODS Patients were given gemcitabine (1000 mg/m2/week, 3 weeks every 4 weeks) plus erlotinib (100 mg/day orally continuously) until disease progression/unacceptable toxicity. The primary end point was OS. RESULTS A total of 153 eligible patients were enrolled (grade≥2 rash, 25%; grade<2 rash, 75%). OS was longer in patients with grade≥2 rash versus grade<2 (11 versus 5 months; P<0.001). Progression-free survival was longer in patients with grade≥2 rash versus grade<2 (6 versus 3 months; P<0.001) and shorter in those without rash versus grade 1 (2 versus 4 months; P=0.005) or grade≥2 (2 versus 6 months; P<0.001). Patients with grade≥2 rash showed higher rates of overall response (21% versus 7%; P<0.05) and disease control (84% versus 43%; P<0.05) versus grade<2. CONCLUSIONS This study prospectively confirms the relationship between rash and longer OS in unresectable locally advanced/metastatic pancreatic cancer treated with erlotinib plus gemcitabine.