The great need to overcome osimertinib resistance in advanced non-small cell lung cancer: from combination strategies to fourth-generation tyrosine kinase inhibitors.
The great need to overcome osimertinib resistance in advanced non-small cell lung cancer: from combination strategies to fourth-generation tyrosine kinase inhibitors.
Project description:PurposeResistance to third-generation EGFR inhibitors including osimertinib arises in part from the C797S mutation in EGFR. Currently, no targeted treatment option is available for these patients. We have developed a new EGFR tyrosine kinase inhibitor (TKI), BBT-176, targeting the C797S mutation.Patients and methodsRecombinant EGFR proteins and Ba/F3 cell lines, patient-derived cells, and patient-derived xenografts expressing mutant EGFRs were used to test the inhibitory potency and the anticancer efficacy of BBT-176 both in vitro and in vivo. Patient case data are also available from an ongoing phase I clinical trial (NCT04820023).ResultsThe half maximal inhibitory concentration (IC50) of BBT-176 against EGFR 19Del/C797S, EGFR 19Del/T790M/C797S, and EGFR L858R/C797S proteins were measured at 4.36, 1.79, and 5.35 nmol/L, respectively (vs. 304.39, 124.82, and 573.72 nmol/L, for osimertinib). IC50 values of BBT-176 against Ba/F3 cells expressing EGFR 19Del/C797S, EGFR 19Del/T790M/C797S, EGFR L858R/C797S, and EGFR L858R/T790M/C797S were 42, 49, 183, and 202 nmol/L, respectively (vs. 869, 1,134, 2,799, and 2,685 nmol/L for osimertinib). N-ethyl-N-nitrosourea mutagenesis suggested that BBT-176 treatment does not introduce any secondary mutations in the EGFR gene but increases EGFR expression levels. Combined with the EGFR antibody cetuximab, BBT-176 effectively suppressed the growth of BBT-176-resistant clones. BBT-176 strongly inhibited the tumor growth, and in some conditions induced tumor regression in mouse models. In the clinical trial, two patients harboring EGFR 19Del/T790M/C797S in blood showed tumor shrinkage and radiologic improvements.ConclusionsBBT-176 is a fourth-generation EGFR inhibitor showing promising preclinical activity against NSCLC resistant to current EGFR TKI, with early clinical efficacy and safety.
Project description:Osimertinib (AZD9291 or TAGRISSO) is a promising and approved third-generation EGFR tyrosine kinase inhibitor (TKI) for treating patients with advanced non-small cell lung cancer (NSCLC) harboring EGFR-activating mutations or the resistant T790M mutation. However, the inevitable emergence of acquired resistance limits its long-term efficacy. A fuller understanding of the mechanism of action of osimertinib and its linkage to acquired resistance will enable the development of more efficacious therapeutic strategies. Consequently, we have identified a novel connection between osimertinib or other EGFR-TKIs and c-Myc. Osimertinib rapidly and sustainably decreased c-Myc levels primarily via enhancing protein degradation in EGFR-mutant (EGFRm) NSCLC cell lines and xenograft tumors. c-Myc levels were substantially elevated in different EGFRm NSCLC cell lines with acquired resistance to osimertinib in comparison with their corresponding parental cell lines and could not be reduced any further by osimertinib. Consistently, c-Myc levels were elevated in the majority of EGFRm NSCLC tissues relapsed from EGFR-TKI treatment compared with their corresponding untreated baseline c-Myc levels. Suppression of c-Myc through knockdown or pharmacologic targeting with BET inhibitors restored the response of resistant cell lines to osimertinib. These findings indicate that c-Myc modulation mediates the therapeutic efficacy of osimertinib and the development of osimertinib acquired resistance. Furthermore, they establish c-Myc as a potential therapeutic target and warrant clinical testing of BET inhibition as a potential strategy to overcome acquired resistance to osimertinib or other EGFR inhibitors. SIGNIFICANCE: This study demonstrates a critical role of c-Myc modulation in mediating therapeutic efficacy of osimertinib including osimertinib acquired resistance and suggests targeting c-Myc as a potential strategy to overcome osimertinib acquired resistance.
Project description:The first mineralocorticoid receptor (MR) antagonist, spironolactone, was developed almost 60 years ago to treat primary aldosteronism and pathological edema. Its use waned in part because of its lack of selectivity. Subsequently, knowledge of the scope of MR function was expanded along with clinical evidence of the therapeutic importance of MR antagonists to prevent the ravages of inappropriate MR activation. Forty-two years elapsed between the first and MR-selective second generation of MR antagonists. Fifteen years later, despite serious shortcomings of the existing antagonists, a third-generation antagonist has yet to be marketed. Progress has been slowed by the lack of appreciation of the large variety of cell types that express the MR and its diverse cell-type-specific actions, and also its unique complex interaction actions at the molecular level. New MR antagonists should preferentially target the inflammatory and fibrotic effects of MR and perhaps its excitatory effects on sympathetic nervous system, but not the renal tubular epithelium or neurons of the cortex and hippocampus. This review briefly describes efforts to develop a third-generation MR antagonist and why fourth generation antagonists and selective agonists based on structural determinants of tissue and ligand-specific MR activation should be contemplated.
Project description:Poly(ADP-ribose) polymerase (PARP) enzymes have been shown to be essential for DNA repair pathways, including homologous recombination repair (HRR). Cancers with HRR defects (e.g., BRCA1 and BRCA2 mutations) are targets for PARP inhibitors (PARPis) based on the exploitation of "synthetic lethality". As a result, PARPis offer a promising treatment option for advanced ovarian and breast cancers with deficiencies in HRR. However, acquired resistance to PARPis has been reported for most tumors, and not all patients with BRCA1/2 mutations respond to PARPis. Therefore, the formulation of effective treatment strategies to overcome resistance to PARPis is urgently necessary. This review summarizes the molecular mechanism of therapeutic action and resistance to PARPis, in addition to emerging combination treatment options involving PARPis.
Project description:Many initially successful anticancer therapies lose effectiveness over time, and eventually, cancer cells acquire resistance to the therapy. Acquired resistance remains a major obstacle to improving remission rates and achieving prolonged disease-free survival. Consequently, novel approaches to overcome or prevent resistance are of significant clinical importance. There has been considerable interest in treating non-small cell lung cancer (NSCLC) with combinations of EGFR-targeted therapeutics (e.g., erlotinib) and cytotoxic therapeutics (e.g., paclitaxel); however, acquired resistance to erlotinib, driven by a variety of mechanisms, remains an obstacle to treatment success. In about 50% of cases, resistance is due to a T790M point mutation in EGFR, and T790M-containing cells ultimately dominate the tumor composition and lead to tumor regrowth. We employed a combined experimental and mathematical modeling-based approach to identify treatment strategies that impede the outgrowth of primary T790M-mediated resistance in NSCLC populations. Our mathematical model predicts the population dynamics of mixtures of sensitive and resistant cells, thereby describing how the tumor composition, initial fraction of resistant cells, and degree of selective pressure influence the time until progression of disease. Model development relied upon quantitative experimental measurements of cell proliferation and death using a novel microscopy approach. Using this approach, we systematically explored the space of combination treatment strategies and demonstrated that optimally timed sequential strategies yielded large improvements in survival outcome relative to monotherapies at the same concentrations. Our investigations revealed regions of the treatment space in which low-dose sequential combination strategies, after preclinical validation, may lead to a tumor reduction and improved survival outcome for patients with T790M-mediated resistance.
Project description:Breathing, being predominantly an automatic action, is often taken for granted. However, respiratory diseases affect millions of people globally, emerging as one of the major causes of disability and death overall. Among the respiratory dysfunctions, tracheal alterations have always represented a primary challenge for clinicians, biologists, and engineers. Indeed, in the case of wide structural alterations involving more than 50% of the tracheal length in adults or 30% in children, the available medical treatments are ineffective or inapplicable. So far, a plethora of reconstructive approaches have been proposed and clinically applied to face this growing, unmet medical need. Unfortunately, none of them has become a well-established and routinely applied clinical procedure to date. This review summarizes the main clinical reconstructive attempts and classifies them as non-tissue engineering and tissue engineering strategies. The analysis of the achievements and the main difficulties that still hinder this field, together with the evaluation of the forefront preclinical experiences in tracheal repair/replacement, is functional to promote a safer and more effective clinical translation in the near future.
Project description:Epidermal growth factor receptor (EGFR), the receptor for members of the epidermal growth factor family, regulates cell proliferation and signal transduction; moreover, EGFR is related to the inhibition of tumor cell proliferation, angiogenesis, invasion, metastasis, and apoptosis. Therefore, EGFR has become an important target for the treatment of cancer, including non-small cell lung cancer, head and neck cancer, breast cancer, glioma, cervical cancer, and bladder cancer. First- to third-generation EGFR inhibitors have shown considerable efficacy and have significantly improved disease prognosis. However, most patients develop drug resistance after treatment. The challenge of overcoming intrinsic and acquired resistance in primary and recurrent cancer mediated by EGFR mutations is thus driving the search for alternative strategies in the design of new therapeutic agents. In view of resistance to third-generation inhibitors, understanding the intricate mechanisms of resistance will offer insight for the development of more advanced targeted therapies. In this review, we discuss the molecular mechanisms of resistance to third-generation EGFR inhibitors and review recent strategies for overcoming resistance, new challenges, and future development directions.
Project description:Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are effective in patients with non-small-cell lung cancer (NSCLC) harboring EGFR mutations. However, due to acquired resistance to EGFR-TKIs, even patients on third-generation osimertinib have a poor prognosis. Resistance mechanisms are still not fully understood. Here, we demonstrate that the increased expression of MUSASHI-2 (MSI2), an RNA-binding protein, is a novel mechanism for resistance to EGFR-TKIs. We found that after a long-term exposure to gefitinib, the first-generation EGFR-TKI lung cancer cells harboring the EGFR-TKI-sensitive mutations became resistant to both gefitinib and osimertinib. Although other mutations in EGFR were not found, expression levels of Nanog, a stemness core protein, and activities of aldehyde dehydrogenase (ALDH) were increased, suggesting that cancer stem-like properties were increased. Transcriptome analysis revealed that MSI2 was among the stemness-related genes highly upregulated in EGFR-TKI-resistant cells. Knockdown of MSI2 reduced cancer stem-like properties, including the expression levels of Nanog, a core stemness factor. We demonstrated that knockdown of MSI2 restored sensitivity to osimertinib or gefitinib in EGFR-TKI-resistant cells to levels similar to those of parental cells in vitro. An RNA immunoprecipitation (RIP) assay revealed that antibodies against MSI2 were bound to Nanog mRNA, suggesting that MSI2 increases Nanog expression by binding to Nanog mRNA. Moreover, overexpression of MSI2 or Nanog conferred resistance to osimertinib or gefitinib in parental cells. Finally, MSI2 knockdown greatly increased the sensitivity to osimertinib in vivo. Collectively, our findings provide proof of principle that targeting the MSI2-Nanog axis in combination with EGFR-TKIs would effectively prevent the emergence of acquired resistance.
Project description:Chimeric antigen receptor T (CAR-T) cell therapy is an emerging and effective cancer immunotherapy. Especially in hematological malignancies, CAR-T cells have achieved exciting results. Two Anti-CD19 CAR-T therapies have been approved for the treatment of CD19-positive leukemia or lymphoma. However, the application of CAR-T cells is obviously hampered by the adverse effects, such as cytokines release syndrome and on-target off-tumor toxicity. In some clinical trials, patients quitted the treatment of CAR-T cells due to life-threatening toxicity. Seeking to alleviate these toxicities or prevent the occurrence, researchers have developed a number of safety strategies of CAR-T cells, including suicide genes, synthetic Notch receptor, on-switch CAR, combinatorial target-antigen recognition, bispecific T cell engager and inhibitory CAR. This review summarized the preclinical studies and clinical trials of the safety strategies of CAR-T cells and their respective strengths and weaknesses.