Phase II study of panitumumab combined with capecitabine and oxaliplatin as first-line treatment in metastatic colorectal cancer patients: clinical results including extended tumor genotyping

Performance of capecitabine in novel combination therapies in colorectal cancer

Colorectal cancer is one of the most common cancers throughout the world, and no definitive cure has ever been found. Perhaps a new insight into the effectiveness of chemotherapy drugs could help better treat patients. Targeted therapies have significantly improved the median overall survival of colorectal cancer patients. One of the standard chemotherapy regimens used for colorectal cancer is capecitabine, which is important in monotherapy and combination therapies. Capecitabine, with other chemotherapeutic agents (irinotecan, oxaliplatin, perifosine, 17-allylamino-17-demethoxygeldanamycin, aspirin, celecoxib, statins, quinacrine, inositol hexaphosphate and inositol, cystine/theanine, curcumin, and isorhamnetin), and biological ones (antibodies) plays an important role in the inhibition of some signaling pathways, increasing survival, reducing tumor growth and side effects of capecitabine. However, some drugs, such as proton pump inhibitors, are negatively related to capecitabine; therefore, the purpose of this work is to review and discuss the performance of capecitabine combination therapies in colorectal cancer.

The Role of p53 Dysfunction in Colorectal Cancer and Its Implication for Therapy

Colorectal cancer (CRC) is one of the most common and fatal cancers worldwide. The carcinogenesis of CRC is based on a stepwise accumulation of mutations, leading either to an activation of oncogenes or a deactivation of suppressor genes. The loss of genetic stability triggers activation of proto-oncogenes (e.g., KRAS) and inactivation of tumor suppression genes, namely TP53 and APC, which together drive the transition from adenoma to adenocarcinoma. On the one hand, p53 mutations confer resistance to classical chemotherapy but, on the other hand, they open the door for immunotherapy, as p53-mutated tumors are rich in neoantigens. Aberrant function of the TP53 gene product, p53, also affects stromal and non-stromal cells in the tumor microenvironment. Cancer-associated fibroblasts together with other immunosuppressive cells become valuable assets for the tumor by p53-mediated tumor signaling. In this review, we address the manifold implications of p53 mutations in CRC regarding therapy, treatment response and personalized medicine.

Circulating Tumor DNA Is Capable of Monitoring the Therapeutic Response and Resistance in Advanced Colorectal Cancer Patients Undergoing Combined Target and Chemotherapy

Colorectal cancer (CRC) is a highly lethal disease worldwide. The majority of patients receiving targeted therapy or chemotherapy develop drug resistance, while its molecular mechanism remains to be elucidated. The plasma circulating tumor DNA (ctDNA) exhibited the potential in identifying gene variations and monitoring drug resistance in CRC treatment. In this study, we monitored the ctDNA mutational changes in advanced CRC patients underwent first-line therapy with bevacizumab and cetuximab combined with chemotherapy. The mutation spectrum of 43 patients was established by a 605-gene next-generation sequencing (NGS) panel. The baseline measurement shows that genes with the highest mutation frequency were TP53 (74%), APC (58%), KRAS (40%), SYNE1 (33%), LRP1B (23%), TOP1 (23%), and PIK3CA (21%). Mutations in TP53, APC, and KRAS were detected in 29 paired plasma and tissue samples with the consistency of 81, 67, and 42%, respectively. Clinically targetable gene mutations, such as APC, RNF43, SMAD4, BRAD1, KRAS, RAF1, and TP53, were also identified in ctDNA. The overall consistency between ctDNA and tissue samples was 54.6%. Alleviation of mutational burden in BRAF, KRAS, AMER1, and other major driving genes was observed following the first-line therapy. Patients with KRAS and TP53 mutations in tissues appeared to benefit more than the wild-type counterpart. The dynamic change of plasma mutation status was consistent with the tissue tumor burden and was closely correlated with disease progression. In conclusion, ctDNA monitoring is a useful method for molecular genotyping of colorectal cancer patients. Dynamic changes in resistance can be sensitively monitored by gene variation status, which potentially helps to develop treatment strategy.

Metformin revert insulin-induced oxaliplatin resistance by activating mitochondrial apoptosis pathway in human colon cancer HCT116 cells

BACKGROUND

Several studies have suggested that drug resistance in colon cancer patients with diabetes may be associated with long-term insulin administration, which in turn decreases the survival rate. Metformin is a commonly used drug to treat diabetes but has been recently demonstrated to have a potential therapeutic effect on colon cancer. This study aimed to elucidate the underlying mechanism by which metformin reverts insulin-induced oxaliplatin resistance in human colon cancer HCT116 cells.

METHODS

Two colon cancer cell lines (HCT116 and LoVo) were used to verify whether the expression of insulin receptor substrate 1 (IRS-1) could impact the half maximal inhibitory concentration (IC50) of oxaliplatin after chronic insulin treatment. The IC50 of oxaliplatin in both cell lines was measured to identify metformin sensitization to oxaliplatin. The adenosine monophosphate-activated protein kinase (AMPK) inhibitor, namely AMPK small interfering RNA, was used to block AMPK activation to identify critical proteins in the AMPK/Erk signaling pathway. Bcl-2 is a vital antiapoptotic protein involved in the mitochondrial apoptosis pathway. Finally, immunofluorescence and electron microscopy were performed to investigate how metformin affects the ultrastructural integrity of mitochondria.

RESULTS

The IC50 of oxaliplatin in HCT116 cells was noticeably increased. After the cells were treated with metformin, oxaliplatin resistance was reversed. According to the results of the western blotting assay of vital proteins involved in the classical apoptosis pathway, cleaved caspase-9 was noticeably upregulated, suggesting that the mitochondrial apoptosis pathway was activated. These results were verified by imaging of mitochondria using electron microscopy. The AMPK/Erk signaling pathway experiments revealed that the upregulation of Bcl-2 induced by insulin through Erk phosphorylation was inhibited by metformin and that such inhibition could be mitigated by the inhibition of AMPK.

CONCLUSIONS

Insulin-induced oxaliplatin resistance was reversed by metformin-mediated AMPK activation. Accordingly, metformin is likely to sensitize patients with diabetes to chemotherapeutic drugs used to treat colon cancer.

Patterns of practice and pharmacoeconomic analysis of the management of patients with metastatic renal cell carcinoma (mRCC) in Greece--the CRISIS study. A retrospective analysis by the Hellenic Genitourinary Cancer Group (HGUCG)

Background:Metastatic RCC (mRCC) treatment has been revolutionized with 11 approved targeted agents. We report patterns of practice, outcomes and pharmacoeconomic analyses after the introduction of targeted therapy. Patients and methods: CRISIS was a retrospective multicenter study of mRCCpatients who received targeted therapy . Results were related to the start of 1st-line therapy, with a cut off at 1 January 2011 in order to depict the impact of increased availability of effective options. Results: 164 patients, were included. 70.1% and 44.5% received 2nd and 3rd-line therapy, respectively. More patients were treated in 2nd-line after 1 January 2011. After a median follow-up of 55.1 months, median progression-free (PFS) and overall survival (OS) were 10.7 (95% confidence intervals [CI]: 8.3-13.7), 7.3 (95% CI: 5.1-8.6), 5.8 (95% CI: 3.8-7.8) and 34 (95% CI: 28.5-39.8), 22.4 (95% CI: 16-32.1), 18.3 (95% CI: 12.4-26.4) months for first, second and third line, respectively. Efficacy of sunitinib and pazopanib in 1st-line were similar. The mean total cost/patient was 35,012.2 Euros (standard deviation [SD]: 28,971.5). Conclusions: Our study confirms previous real-world data suggesting that continuing advances in the treatment of mRCC produce favorable outcomes in everyday practice. Pharmacoeconomic analyses are important for cost-effective utilization of emerging novel therapies.