Development Of Drug Resistance Mechanisms Research Articles

Comparison between antineoplastic treatments with selective inhibitors (BRAF/MEK) and the new potentials combinatorial therapies for metastatic melanoma

Melanoma is responsible for most skin cancer related mortalities, and its best prognosis is related to early diagnosis and treatment. In this sense much has been studied about the treatment of the disease, relating mainly to selective inhibitors of signaling pathways. Therefore, the present review addresses the use of monotherapies of BRAF (vemurafenib and dabrafenib) and MEK (trametinib) inhibitors, the possible combinations between them and other therapeutic options that may be promising to participate on the neoadjuvant and adjuvant treatment with the selective inhibitors, since the main limitations in treatment with these inhibitors is the frequent development of drug resistance mechanisms. In order to obtain the necessary content, a bibliographic review was carried out in the following databases of the Virtual Health Library, PubMed, Scielo and Google Academic, using the following keywords: melanoma, BRAF and MEK inhibitors, dabrafenib monotherapy and vemurafenib, dabrafenib and trametinib combinations, protein disulfide isomerase action, immunotherapy in the treatment of metastatic melanoma. After the information survey it was possible to conclude that dabrafenib + trametinib combination therapy is more advantageous in view of the adverse effects, quality of life and progression free survival of the patient when compared directly to selective chemotherapy monotherapies, and this may be considered for future studies that include, for example, combination with immunotherapy or quercetin, a potential natural inhibitor for PDI.

Immune Dysfunctions and Immune-Based Therapeutic Interventions in Chronic Lymphocytic Leukemia.

Chronic lymphocytic leukemia (CLL) is a B-cell malignancy characterized by a wide range of tumor-induced alterations, which affect both the innate and adaptive arms of the immune response, and accumulate during disease progression. In recent years, the development of targeted therapies, such as the B-cell receptor signaling inhibitors and the Bcl-2 protein inhibitor venetoclax, has dramatically changed the treatment landscape of CLL. Despite their remarkable anti-tumor activity, targeted agents have some limitations, which include the development of drug resistance mechanisms and the inferior efficacy observed in high-risk patients. Therefore, additional treatments are necessary to obtain deeper responses and overcome drug resistance. Allogeneic hematopoietic stem cell transplantation (HSCT), which exploits immune-mediated graft-versus-leukemia effect to eradicate tumor cells, currently represents the only potentially curative therapeutic option for CLL patients. However, due to its potential toxicities, HSCT can be offered only to a restricted number of younger and fit patients. The growing understanding of the complex interplay between tumor cells and the immune system, which is responsible for immune escape mechanisms and tumor progression, has paved the way for the development of novel immune-based strategies. Despite promising preclinical observations, results from pilot clinical studies exploring the safety and efficacy of novel immune-based therapies have been sometimes suboptimal in terms of long-term tumor control. Therefore, further advances to improve their efficacy are needed. In this context, possible approaches include an earlier timing of immunotherapy within the treatment sequencing, as well as the possibility to improve the efficacy of immunotherapeutic agents by administering them in combination with other anti-tumor drugs. In this review, we will provide a comprehensive overview of main immune defects affecting patients with CLL, also describing the complex networks leading to immune evasion and tumor progression. From the therapeutic standpoint, we will go through the evolution of immune-based therapeutic approaches over time, including i) agents with broad immunomodulatory effects, such as immunomodulatory drugs, ii) currently approved and next-generation monoclonal antibodies, and iii) immunotherapeutic strategies aiming at activating or administering immune effector cells specifically targeting leukemic cells (e.g. bi-or tri-specific antibodies, tumor vaccines, chimeric antigen receptor T cells, and checkpoint inhibitors).

Antitoxic and chemosensitizing effects of bovine lactoferrin and muramyl dipeptide in Ehrlich solid tumor-bearing mice treated with cisplatin.

Background: Despite the effectiveness of anti-cancer chemotherapy, it is associated with serious adverse side effects and the development of drug-resistance mechanisms. Immune dysfunction is considered one of the most serious adverse effects of anti-cancer chemotherapy, which increases the susceptibility of the patients to infection. Co-administration of immunomodulatory agents as adjuvant therapy with chemotherapy will result in better anti-tumor responses with fewer side effects. Aim: This study was designed to evaluate the ameliorative effects of bovine lactoferrin (bLF) and muramyl dipeptide (MDP) against toxicity induced by cisplatin in tumor-bearing mice. Materials and Methods: In this study, MDP or bLF was co-treated with cisplatin in mice bearing Ehrlich solid tumor (EST). Results: Co- treatment of cisplatin with MDP or bLF enhanced the anti-tumor effects of cisplatin to induce a reduction of the tumor size, proliferative capabilities of tumor cells accompanied by an elevation in the apoptotic profile of tumor cells. Moreover, co- treatments of Cisplatin with bLF or MDP reversed the Cisplatin-induced immune suppression and partially restored splenocyte proliferation, immune organ indices, hematological profile, liver and kidney functions, and histological structure. Conclusion: Both bLF and MDP were able to act as adjuvant therapy with anti-cancer chemotherapy through their abilities to enhance the chemotherapy curative effects, modulate the immune response against tumor cells, and to some extent ameliorate the adverse toxic effects of the chemotherapy.

Mechanisms underlying the increased chemosensitivity of bortezomib-resistant multiple myeloma by silencing nuclear transcription factor Snail1.

The Snail family transcriptional repressor 1 gene (Snail1) was screened in multiple myeloma cells (MMCs) from bortezomib-resistant MM patients and was found to be significantly associated with the development of drug-resistance mechanisms. In the present study, we first confirmed that the protein expression of Snail1 in bortezomib-resistant MMCs was significantly higher than that in MMCs without bortezomib resistance. The mechanistic studies confirmed that the enhancement of Snail1 expression in bortezomib-resistant MMCs directly upregulated transcription of the intracellular MDR1 gene to immediately develop multiple drug resistance mechanisms and inhibited P53 protein expression through the Snail1/hsa-miRNA-22-3p/P53 pathway to inhibit tumor cell apoptosis. By upregulating MDR1 and downregulating P53, Snail1 induced the drug resistance of MMCs to bortezomib, while Snail1 gene silencing effectively improved the drug sensitivity of MMCs to bortezomib chemotherapy. The present study further elucidated the drug resistance mechanisms of MMCs and provides evidence for increased clinical efficacy of bortezomib in MM patients.

Current and Emerging Applications of Droplet Digital PCR in Oncology.

The clinical management of cancer has evolved in recent years towards more personalized strategies that require a comprehensive knowledge of the complex molecular features involved in tumor growth and evolution, and the development of drug resistance mechanisms leading to disease progression. Droplet digital PCR (ddPCR) has become one of the most accurate and reliable tools for the examination of genetic alterations in a wide variety of cancers because of its high sensitivity and specificity. ddPCR is currently being applied for absolute allele quantification, rare mutation detection, analysis of copy number variations, DNA methylation, and gene rearrangements in different kinds of clinical samples. This methodology has proven useful for the evaluation of archival tumor tissues, where poor DNA quality and limited sample availability are major obstacles for standard methods, providing less subjective and more automated quantitative results. However, most applications of ddPCR in cancer are focused on liquid biopsies (including cell-free DNA as well as circulating tumor cells) because these represent non-invasive alternatives to tissue biopsies that can more accurately reflect intratumoral heterogeneity and track the dynamic changes in tumor burden that occur in response to treatment at different times during follow-up. A broad spectrum of molecular markers have been interrogated in blood using ddPCR for diagnostic, predictive, and monitoring purposes in various malignancies. Emerging alternative approaches using other body fluids such as cerebrospinal fluid and urine are also currently being developed. This article aims to give a complete overview of ddPCR applications for molecular screening in oncology.

ASSOCIATION BETWEEN SPECIFIC FEATURES OF GATA3 TRANSCRIPTION FACTOR EXPRESSION AND LYMPH NODE METASTASIS IN LUMINAL BREAST CANCER

Currently, the study of the markers of cell differentiation, proliferative regulators, and molecules involved in the development of drug resistance mechanisms in breast cancer is extremely important. The transcription factor GATA3 plays an essential role in the differentiation and proliferative activity of luminal breast cancer cells, being a tumor suppressor. The GATA3 positive expression is most frequently observed in invasive carcinoma of no special type. High expression of GATA3 is associated with low-grade ER-positive cancer with a favorable prognosis. Low GATA3 expression is observed in patients with high-grade and hormone receptor-negative cancer. The study of GATA3 expression is necessary for understanding the development of drug resistance mechanisms and developing approaches to overcome them as well as for determining the response to hormone therapy. Aim. The present study was undertaken to study the expression characteristics of the transcription factor GATA3 in patients with luminal breast cancer and to evaluate their relationship with the parameters of lymphogenous metastasis. Material and methods. The study included 64 patients with stage T1–4N1–3M0 invasive breast cancer. The primary tumor tissue and all removed lymph nodes were morphologically examined. The diagnosis was established according to the WHO criteria (2012). Results. Low GATA3 expression was associated with a high risk of lymph node metastases, while high GATA3 expression was associated with the absence of lymph node metastases. Heterogeneous GATA3 expression was associated with high risk of lymph node metastasis, and as a consequence, with poor prognosis. Conclusion. The relationship between the expression of GATA3 protein and lymphogenic metastasis in patients with luminal breast cancer was found.

Abstract A154: Mechanisms of cellular resistance to the growth inhibitory and cytotoxic effects of MDM2-p53 binding antagonists

Abstract Background: About 50% of solid tumors and more than 80% of haematological malignancies express wild-type p53 at diagnosis. Therefore, activation of the p53 pathway by antagonizing its negative regulator Murine Double Minute 2 (MDM2) may offer a new therapeutic strategy for cancer treatment. Recently, several potent and selective small molecule antagonists of the p53-MDM2 protein-protein interaction have been developed. Studies with these compounds have strengthened the concept that selective, non-genotoxic p53 activation may in some circumstances represent an alternative to current cytotoxic chemotherapy. Aims: To investigate the potential for drug resistance against p53-MDM2 interaction antagonists and to establish therapeutic strategies to circumvent this. Methods: NGP neuroblastoma and SJSA-1 osteosarcoma cell lines have been used to select a series of clonal variants resistant to two potent small molecule inhibitors of the MDM2-p53 interaction Nutlin-3 [Science 2004, 303, 844] and MI63 [J.Med.Chem. 2005, 48, 909]. The drug resistance phenotype of these clones was evaluated by SRB growth inhibition assay, western blotting for activation of p53 and downstream mediators of p53 dependent growth inhibition and cytotoxicity, and caspase-3/7 activation analysis, in response to drug treatment. DNA sequence analysis for p53 mutation detection was also conducted to explore possible resistance mechanisms. Results: Following 60-day exposure to 1-5µM plus 60-day exposure to 5-40µM of MI63 or Nutlin-3 respectively, several clones were selected showing 11.5–43.2 fold increases in GI50 values. Clones selected for resistance to one of the agents showed cross-resistance to the other. This increased resistance was reflected in reduced activation of growth inhibition and apoptosis pathways downstream of p53, although induction of p53 protein itself was little changed compared to parental cell lines. All clones exhibited undetectable accumulation of MDM2 and p21 proteins compared with the marked changes seen with parental cells after treatment with 20 µM of Nutlin-3 or 5 µM MI63 for 4–6 hours, even though the p53 protein accumulated to the same extent as parental cells. Decreased cleavage of caspase-3 and PARP proteins were also observed, consistent with the reduced apoptosis. Caspase-3/7 enzymatic activity in the resistant clones in response to exposure to MI63 or Nutlin-3 for 48 hours was also significantly reduced compared to the response in parental cell lines. Point missense mutations of the p53 gene were observed within the resistant cell clones of both SJSA-1 and NGP cell lines. Conclusions: As with other therapeutic agents, treatment with MDM2-p53 binding antagonists is likely to be subject to the development of drug resistance mechanisms. A panel of clones selected for resistance to Nutlin-3 and MI63 showed impaired activation of growth inhibitory and apoptotic pathways downstream of p53 in response to treatment with these agents compared to parental cells. DNA sequencing and p53 pathway analysis were consistent with a p53 mutation resistance mechanism. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A154.

A phase I/II dose-escalation trial of EPO906 every 3 weeks in patients with relapsed/refractory ovarian, primary fallopian, or primary peritoneal cancer

5102 Background: Patients (pts) with newly diagnosed advanced ovarian cancer generally receive a taxane in combination with a platinum agent. However, pts refractory to this therapy have few treatment options. Taxane efficacy can be limited by the development of drug-resistance mechanisms, and taxanes are associated with neutropenia and neuropathies. EPO906 is a potent microtubule stabilizer that has demonstrated clinical cytotoxic activity in taxane-sensitive, -resistant, and -refractory tumors. In a phase I/II study, we investigated the safety and efficacy of EPO906 in pts with advanced ovarian, primary fallopian, or primary peritoneal cancer who had failed to respond to or had relapsed within 6 months of first-line taxane plus platinum therapy. Methods: During phase I, dose escalation followed the standard 3 + 3 design until the MTD was reached. Pts received EPO906 at a starting dose of 6.5 mg/m2 via 5-min IV infusion once every 3 wks with aggressive diarrhea management at first sign of abdominal cramping. During phase II, pts will be treated at the MTD for 6 cycles or until disease progression. Results: To date, 6 pts have been enrolled in 2 cohorts receiving 6.5 mg/m2 (n = 3) or 7.0 mg/m2 (n = 3) EPO906. Median age was 56 yrs (range, 33 - 69 yrs). Before study entry, these pts had received a median of 6 cycles of carboplatin plus paclitaxel. Pts have received a median of 3 cycles (range, 2 - 6 cycles) of EPO906. No DLTs have been reported; thus, the MTD has not been reached. Grade 3 AEs—vomiting (n = 2), diarrhea (n = 1), and dehydration (n = 1)—were observed in cycle 2 and thus were not DLT. Grade ≤ 2 diarrhea (n = 2) and nausea (n = 1) were also reported. No pts experienced hematologic or peripheral neurologic toxicity. Radiologic tumor assessment shows 2 pts with SD (1 at 4 cycles; 1 at 6 cycles). Conclusion: Preliminary data indicate that EPO906 administered once every 3 wks is safe and well tolerated in this population. MTD has not been reached and dose escalation continues. Phase II portion of this study will assess the clinical activity of EPO906 in the treatment of advanced ovarian, primary fallopian, or primary peritoneal cancer. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Novartis Pharma AG Novartis Pharma AG Novartis Pharma AG Novartis Pharma AG; Novartis Pharmaceuticals, Inc. Novartis Pharmaceuticals, Inc.

A phase I/II dose-escalation trial of EPO906 every 3 weeks in patients with relapsed/refractory ovarian, primary fallopian, or primary peritoneal cancer

5102 Background: Patients (pts) with newly diagnosed advanced ovarian cancer generally receive a taxane in combination with a platinum agent. However, pts refractory to this therapy have few treatment options. Taxane efficacy can be limited by the development of drug-resistance mechanisms, and taxanes are associated with neutropenia and neuropathies. EPO906 is a potent microtubule stabilizer that has demonstrated clinical cytotoxic activity in taxane-sensitive, -resistant, and -refractory tumors. In a phase I/II study, we investigated the safety and efficacy of EPO906 in pts with advanced ovarian, primary fallopian, or primary peritoneal cancer who had failed to respond to or had relapsed within 6 months of first-line taxane plus platinum therapy. Methods: During phase I, dose escalation followed the standard 3 + 3 design until the MTD was reached. Pts received EPO906 at a starting dose of 6.5 mg/m2 via 5-min IV infusion once every 3 wks with aggressive diarrhea management at first sign of abdominal cramping. During phase II, pts will be treated at the MTD for 6 cycles or until disease progression. Results: To date, 6 pts have been enrolled in 2 cohorts receiving 6.5 mg/m2 (n = 3) or 7.0 mg/m2 (n = 3) EPO906. Median age was 56 yrs (range, 33 - 69 yrs). Before study entry, these pts had received a median of 6 cycles of carboplatin plus paclitaxel. Pts have received a median of 3 cycles (range, 2 - 6 cycles) of EPO906. No DLTs have been reported; thus, the MTD has not been reached. Grade 3 AEs—vomiting (n = 2), diarrhea (n = 1), and dehydration (n = 1)—were observed in cycle 2 and thus were not DLT. Grade ≤ 2 diarrhea (n = 2) and nausea (n = 1) were also reported. No pts experienced hematologic or peripheral neurologic toxicity. Radiologic tumor assessment shows 2 pts with SD (1 at 4 cycles; 1 at 6 cycles). Conclusion: Preliminary data indicate that EPO906 administered once every 3 wks is safe and well tolerated in this population. MTD has not been reached and dose escalation continues. Phase II portion of this study will assess the clinical activity of EPO906 in the treatment of advanced ovarian, primary fallopian, or primary peritoneal cancer. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Novartis Pharma AG Novartis Pharma AG Novartis Pharma AG Novartis Pharma AG; Novartis Pharmaceuticals, Inc. Novartis Pharmaceuticals, Inc.