Second-line pazopanib in patients with relapsed and refractory small-cell lung cancer: a multicentre phase II study of the Hellenic Oncology Research Group

Small Cell Lung Cancer-An Update on Chemotherapy Resistance

OPINION STATEMENT

Compared to other types of lung cancer, small cell lung cancer (SCLC) exhibits aggressive characteristics that promote drug resistance. Despite platinum-etoposide chemotherapy combined with immunotherapy being the current standard treatment, the rapid development of drug resistance has led to unsatisfactory clinical outcomes. This review focuses on the mechanisms contributing to the chemotherapy resistance phenotype in SCLC, such as increased intra-tumoral heterogeneity, alterations in the tumor microenvironment, changes in cellular metabolism, and dysregulation of apoptotic pathways. A comprehensive understanding of these drug resistance mechanisms in SCLC is imperative for ushering in a new era in cancer research, which will promise revolutionary advancements in cancer diagnosis and treatment methodologies.

The Evolving Scenario of ES-SCLC Management: From Biology to New Cancer Therapeutics

Small cell lung cancer (SCLC) is an aggressive neuroendocrine carcinoma accounting for 15% of lung cancers with dismal survival outcomes. Minimal changes in therapy and prognosis have occurred in SCLC for the past four decades. Recent progress in the treatment of extensive-stage disease (ES-SCLC) has been marked by incorporating immune checkpoint inhibitors (ICIs) into platinum-based chemotherapy, leading to modest improvements. Moreover, few second-line-and-beyond treatment options are currently available. The main limitation for the molecular study of SCLC has been the scarcity of samples, because only very early diseases are treated with surgery and biopsies are not performed when the disease progresses. Despite all these difficulties, in recent years we have come to understand that SCLC is not a homogeneous disease. At the molecular level, in addition to the universal loss of retinoblastoma (RB) and TP53 genes, a recent large molecular study has identified other mutations that could serve as targets for therapy development or patient selection. In recent years, there has also been the identification of new genetic subtypes which have shown us how intertumor heterogeneity exists. Moreover, SCLC can also develop intratumoral heterogeneity linked mainly to the concept of cellular plasticity, mostly due to the development of resistance to therapies. The aim of this review is to quickly present the current standard of care of ES-SCLC, to focus on the molecular landscapes and subtypes of SCLC, subsequently present the most promising therapeutic strategies under investigation, and finally recap the future directions of ongoing clinical trials for this aggressive disease which still remains a challenge.

Novel Therapeutic Options for Small Cell Lung Cancer

PURPOSE OF REVIEW

The aim of this review is to focus on the recent advances in the molecular knowledge of small cell lung cancer (SCLC) and potential promising new treatment strategies, like targeting the DNA damage pathway, epigenetics, angiogenesis, and oncogenic drivers.

RECENT FINDINGS

In the last few years, the addition of immunotherapy to chemotherapy has led to significant improvements in clinical outcomes in this complex neoplasia. Nevertheless, the prognosis remains dismal. Recently, numerous genomic alterations have been identified, and they may be useful to classify SCLC into different molecular subtypes (SCLC-A, SCLC-I, SCLC-Y, SCLC-P). SCLC accounts for 10-20% of all lung cancers, most patients have an extensive disease at the diagnosis, and it is characterized by poor prognosis. Despite the progresses in the knowledge of the disease, efficacious targeted treatments are still lacking. In the near future, the molecular characterisation of SCLC will be fundamental to find more effective treatment strategies.

Small-Cell Lung Cancer-An Update on Targeted and Immunotherapies

Small-cell lung cancer (SCLC) is an aggressive disease with distinct biological and clinical features. The clinical course of SCLC is generally characterised by initial sensitivity to DNA-damaging therapies, followed by early relapse and broad cross resistance to second line agents. Whilst there has been an enormous expansion of effective targeted and immune-based therapeutic options for non-small cell lung cancer (NSCLC) in the last decade, little improvement has been achieved in SCLC treatment and survival due, at least in part, to underappreciated inter- and intra-tumoral heterogeneity. Here we review the current treatment paradigm of SCLC including recent advances made in utilizing immunotherapy and the challenges of identifying a predictive biomarker for immunotherapy response. We examine emerging new targeted therapies, combination immunotherapy and future directions of SCLC treatment research.

Current and Emerging Treatment Options for Patients With Relapsed Small-cell Lung Carcinoma: A Systematic Literature Review

Second-line treatment options are limited for patients with small-cell lung cancer (SCLC). We conducted a PRISMA-standard systematic literature review to evaluate the treatment landscape for patients with relapsed SCLC (PROSPERO number: CRD42022299759). Systematic searches of MEDLINE, Embase, and Cochrane Library were performed (October 2022) to identify publications (prior 5 years) from prospective studies of therapies for relapsed SCLC. Publications were screened against predetermined eligibility criteria; data were extracted to standardized fields. Publication quality was assessed using GRADE. The data were analyzed descriptively, grouped by drug class. Overall, 77 publications involving 6349 patients were included. Studies of tyrosine kinase inhibitors (TKIs) with established cancer indications accounted for 24 publications; topoisomerase I inhibitors for 15; checkpoint inhibitors (CPIs) for 11, and alkylating agents for 9 publications. The remaining 18 publications featured chemotherapies, small-molecule inhibitors, investigational TKIs and monoclonal antibodies, and a cancer vaccine. According to GRADE assessment, 69% of the publications reported low-/very-low-quality evidence; quality limitations included lack of randomization and small sample sizes. Only 6 publications/6 trials reported phase 3 data; 5 publications/2 trials reported phase 2/3 results. Overall, the clinical potential of alkylating agents and CPIs remained unclear; investigations of combination approaches and biomarker-directed usage are warranted. Phase 2 data from TKI trials were consistently promising; no phase 3 data were available. Phase 2 data for a liposomal formulation of irinotecan were promising. We confirmed an absence of promising investigational drug/regimens in late-stage development; thus, relapsed SCLC remains an area of high unmet need.

Personalized treatment of extensive stage small cell lung cancer: A case report and literature review

A 50-year-old female patient presented with post-exercise dyspnea in September 2016, and was subsequently diagnosed with SCLC with multiple brain and spinal metastases. The first-line treatment was etoposide combined with cisplatin and synchronously performed radiotherapy for the brain and spinal cord metastases. She was treated with anlotinib after disease progression in December 2018 and continued to have clinical benefit for nearly 25 months. Unexpectedly, the patient can still benefit from further combination treatment with durvalumab after another disease progression in February 2021. Thus, it may be a potential option to use anlotinib along with immunotherapy after the anlotinib resistance in SCLC, but more clinical data are still needed to confirm it. Moreover, ctDNA dynamic monitoring was performed and reflected the outcome of the process of treatment.

Pazopanib restricts small cell lung cancer proliferation via reactive oxygen species-mediated endoplasmic reticulum stress

Background

Pazopanib is an approved multitarget anticancer agent for soft tissue sarcoma (STS) and renal cell carcinoma (RCC), which is also under clinical investigation for other malignancies, including small cell lung cancer (SCLC). However, the potential anti‐SCLC mechanisms of pazopanib remain unclear.

Methods

Cell viability was evaluated by CCK‐8, apoptotic cell detection was conducted using annexin V/PI staining followed by flow cytometry, and Western blot analysis was used to detect the apoptotic‐related molecules and ER‐stress pathway effectors. The intracellular reactive oxygen species (ROS) level was determined by DCFH‐HA staining followed by flow cytometry. An NCI‐H446 xenograft model was established to evaluate pazopanib on tumor suppression in vivo. Immunohistochemistry (IHC) was used to assess the proliferative activity of xenograft in NCI‐H446 cell‐bearing NOD‐SCID mice.

Results

Pazopanib dose‐ and time‐dependently inhibited SCLC cell proliferation induced significant apoptosis in SCLC cell lines, increased cleaved‐caspase3 and Bax, and decreased Bcl‐2. Moreover, the PERK‐related ER‐stress pathway was potently activated by pazopanib treatment, inhibiting ER‐stress by salubrinal significantly reversing pazopanib‐mediated apoptosis in SCLC cell lines. Furthermore, pazopanib‐induced intracellular ROS levels increased, while inhibiting ROS by NAC significantly reversed pazopanib‐induced apoptosis in SCLC cells. In addition, pazopanib significantly suppressed NCI‐H446 xenograft growth and decreased Ki67 positive cells in the tumor.

Conclusion

Our findings indicate that pazopanib induces SCLC cell apoptosis through the ER‐stress process via upregulation of ROS levels. Further investigation of relevant biomarkers to accurately select patients for benefit from pazopanib should be further investigated.

A phase II study of anlotinib combined with etoposide and platinum-based regimens in the first-line treatment of extensive-stage small cell lung cancer

BACKGROUND

The aim of this prospective, pilot, single-arm phase II trial was to evaluate the safety and efficacy of anlotinib combined with etoposide and platinum-based regimens in the first-line treatment of extensive-stage small cell lung cancer (ES-SCLC).

METHODS

This phase II study was conducted at Fudan University Shanghai Cancer Center between December 2018 and December 2020. All patients received standard chemotherapy (etoposide plus cisplatin/carboplatin) consisting of four courses and anlotinib at 12 mg once per day for 2 weeks followed by a one-week rest. Anlotinib administration was continued until disease progression, intolerable adverse events (AEs) or patient withdrawal from the study. The primary outcome measure was progression-free survival (PFS). The secondary outcome measures were overall survival (OS), objective control rate (ORR), disease control rate (DCR) and AEs.

RESULTS

Thirty-seven patients were included in this study, and 30 patients were eligible for efficacy analysis. ORR and DCR were 90.0% and 96.7%, respectively. The estimated PFS and OS were 6.0 months (95% CI: 1.1-11.9 months) and 14.0 months (95% CI: 8.6-19.4 months), respectively. No unexpected adverse effects were reported. Hypertension (20/37, 54.1%), anemia (16/37, 43.2%), alopecia (15/37, 40.5%), elevated transaminases (9/37, 24.3%) and alkaline phosphatase (9/37, 24.3%) were the most commonly reported AEs. Thirteen patients (35.1%) reported grade 3-5 AEs. No treatment-related deaths occurred during this study.

CONCLUSION

The addition of anlotinib to standard etoposide/platinum chemotherapy achieved encouraging PFS and OS in previously untreated ES-SCLC patients, with an acceptable tolerability profile and no new safety signals observed.

Apatinib as maintenance therapy following standard first-line chemotherapy in extensive disease small cell lung cancer: A phase II single-arm trial

Background

There is a need for the development of therapies to delay cancer progression and prolong survival after initial chemotherapy for the treatment of small cell lung cancer (SCLC). Since apatinib has been found to exert promising effects on cancer patients after standard first‐line chemotherapy, this study aimed to investigate apatinib as a maintenance treatment following first‐line chemotherapy in extensive disease (ED)‐SCLC.

Methods

The primary endpoints were overall survival (OS) and progression‐free survival (PFS). The secondary endpoints included toxicity and safety. Apatinib (250 mg/day) was administered during the chemotherapy interval and as maintenance therapy after 4–6 cycles until the patient's disease progressed, the patient died, or became intolerant to the drug's toxicity.

Results

The patients who received apatinib maintenance treatment had a median PFS of 3.7 months (95% CI: 1.3–6.2 months). The median OS was 16.3 months (95% CI: 9.7–22.8 months). The objective response rate and disease control rate were 50.0% and 66.7%, respectively. Two patients required dose reduction due to adverse effects (AEs). The most common AEs included hypertension (n = 4, 33.3%) and hand‐foot‐skin reaction (n = 2, 16.7%). One patient developed diarrhea, while another patient developed hemoptysis. The most serious AE was intestinal obstruction.

Conclusions

Apatinib maintenance therapy showed promising efficacy and safety to extend the OS/PFS of patients with ED‐SCLC, thus making it a potent therapeutic option in future clinical practice. Given the small sample size of this study, further studies with large sample sizes are needed to validate the findings of the present study.

Recent developments in the treatment of small cell lung cancer

Small cell lung cancer (SCLC) comprises about 15% of all lung cancers. It is an aggressive disease, with early metastasis and a poor prognosis. Until recently, SCLC treatment remained relatively unchanged, with chemotherapy remaining the cornerstone of treatment. In this overview we will highlight the recent advances in the field of staging, surgery, radiotherapy and systemic treatment. Nevertheless, the prognosis remains dismal and there is a pressing need for new treatment options. We describe the progress that has been made in systemic treatment by repurposing existing drugs and the addition of targeted treatment. In recent years, immunotherapy entered the clinic with high expectations of its role in the treatment of SCLC. Unravelling of the genomic sequence revealed new possible targets that may act as biomarkers in future treatment of patients with SCLC. Hopefully, in the near future, we will be able to identify patients who may benefit from targeted therapy or immunotherapy to improve prognoses.

Anlotinib vs placebo as third- or further-line treatment for patients with small cell lung cancer: a randomised, double-blind, placebo-controlled Phase 2 study

BACKGROUND

This study aimed to evaluate the efficacy and safety of anlotinib as a third-line and subsequent treatment for patients with small cell lung cancer (SCLC).

METHODS

We conducted this Phase 2 trial at 11 institutions in China. Patients with pathologically confirmed SCLC who failed at least two lines of chemotherapy were enrolled. Subjects were randomly assigned in a 2:1 ratio to receive either anlotinib 12 mg orally once daily for 14 days every 3 weeks or placebo. The primary endpoint was progression-free survival (PFS).

RESULTS

Between March 30, 2017 and June 8, 2018, a total of 82 and 38 patients were randomly assigned to receive anlotinib and placebo. The median PFS was significantly longer in the anlotinib group compared with the placebo group (4.1 months [95% confidence interval (CI), 2.8-4.2] vs 0.7 months [95% CI, 0.7-0.8]; hazard ratio (HR) 0.19 [95% CI, 0.12-0.32], p < 0.0001). Overall survival (OS) was significantly longer with anlotinib than placebo (7.3 months [95% CI, 6.1-10.3] vs 4.9 months [95% CI, 2.7-6.0]; HR 0.53 [95% CI, 0.34-0.81], p = 0.0029).

CONCLUSIONS

Anlotinib as a third-line or subsequent treatment for Chinese patients with SCLC showed improved PFS and OS than placebo with favourable safety profile.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, number NCT03059797.

Liquid Biopsy for Small Cell Lung Cancer either De Novo or Transformed: Systematic Review of Different Applications and Meta-Analysis

BACKGROUND

The potential added value of liquid biopsy (LB) is not well determined in the case of small cell lung cancer (SCLC), an aggressive tumor that can occur either de novo or from the histologic transformation of non-small cell lung cancer (NSCLC).

METHODS

A systematic review of studies adopting LB in patients with SCLC have been performed to assess the clinical utility of circulating tumor DNA (ctDNA) or circulating tumor cells (CTCs).

RESULTS

After a screening of 728 records, 62 studies (32 evaluating CTCs, 27 ctDNA, and 3 both) met predetermined eligibility criteria. Only four studies evaluated LB in the diagnostic setting for SCLC, while its prognostic significance was evaluated in 38 studies and prominently supported by both ctDNA and CTCs. A meta-analysis of 11 studies as for CTCs enumeration showed an HR for overall survival of 2.63 (1.71-4.05), with a potential publication bias. The feasibility of tumor genomic profiling and the predictive role of LB in terms of response/resistance to chemotherapy was assessed in 11 and 24 studies, respectively, with greater consistency for those regarding ctDNA. Intriguingly, several case reports suggest that LB can indirectly capture the transition to SCLC in NSCLC treated with EGFR tyrosine kinase inhibitors.

CONCLUSIONS

While dedicated trials are needed, LB holds potential clinical roles in both de novo and transformed SCLC. CtDNA analysis appears the most valuable and practicable tool for both disease monitoring and genomic profiling.

A randomized phase 2 trial of apatinib vs observation as maintenance treatment following first-line induction chemotherapy in extensive- stage small cell lung cancer

Background The 5-year survival rate for extensive-disease small-cell lung carcinoma (ED-SCLC) is only 1%. Recently, apatinib exerted promising effects on cancer patients after failure of first-line chemotherapy. Methods This study enrolled 24 ED-SCLC patients to study the efficacy and toxicity of apatinib in combination with chemotherapy and maintenance therapy. The primary endpoints were overall survival (OS) and progression-free survival (PFS). The secondary endpoints included toxicity and safety. Apatinib was given 250 mg/day during the chemotherapy interval, and as maintenance therapy after 4-6 cycles until the patient progressed, died, or was intolerant to drug toxicity. The study further evaluated the cytotoxicity, cell-cycle arrest and apoptotic induction of apatinib in A549 and H446 cells. Results There was no difference in short-term efficacy between combined and chemotherapy groups. Long-term efficacy showed that the median PFS was 7.8 months and 4.9 months in combination and chemotherapy groups, respectively [p = 0.002, HR(95%CI): 0.18(0.06-0.60)]. The median OS was 12.1 months and 8.2 months in combination and chemotherapy groups, respectively [p = 0.023, HR(95%CI): 0.38 (0.16-0.90)]. Multivariate Cox regression analysis showed that apatinib combined with chemotherapy was an independent prognostic factor for OS and PFS. The ECOG score was an independent prognostic factor affecting OS. In vitro analysis showed that apatinib inhibited cell proliferation and caused cell-cycle arrest and apoptosis. Conclusion Apatinib combination/maintenance therapy showed promising efficacy and safety to extend OS/PFS in ED-SCLC and will be a potent therapeutic option in future practice. Although the scale of this study is small, further research on large sample sizes is needed.

Radiotherapy may improve survival of ES-SCLC with distant metastasis only for patients with one metastatic site: A population-based study

The aim of the present study was to investigate the prognostic impact of RT on patients with extensive stage small cell lung cancer (ES-SCLC) and distant metastasis. Using the Surveillance Epidemiology and End Results (SEER) database, 8,595 patients with ES-SCLC exhibiting distant metastasis treated between 2010 and 2013 were identified. Patient baseline characteristics were compared using the χ² test. The Kaplan-Meier test was used to analyze subgroup cancer-specific survival (CSS) rate, and differences were compared using a log-rank test. Univariate and multivariate Cox regression models were used to analyze the prognostic variables on CSS. RT was determined to be an independent prognostic factor for patient CSS (P<0.001). In addition, RT could improve the CSS of patients with ES-SCLC with one metastatic lesion (hazard ratio, 0.63; 95% confidence interval, 0.59-0.68; P<0.001), including the bone, brain, liver and lung metastatic sites. However, for patients with two metastatic sites, RT did not improve CSS regardless of metastasis pattern (all P>0.05). To conclude, RT may improve the survival rate of patients with ES-SCLC with distant metastasis, particularly in those with only one metastatic site.

Soluble fms-like tyrosine kinase-1-enriched exosomes suppress the growth of small cell lung cancer by inhibiting endothelial cell migration

Background

Previous studies have reported that soluble fms‐like tyrosine kinase‐1 (sFlt‐1) possesses anti‐tumor effects by inhibiting angiogenesis in many cancers. Exosomes can be engineered as delivery vehicles for transferring functional biomolecules, such as proteins, lipids, and nucleic acids (DNA, mRNA, and miRNA) to target cells to affect inflammation, apoptosis, and angiogenesis. The purpose of this study was to investigate whether exosomes can function as efficient carriers of sFlt‐1 in vitro and in vivo, to play a role in SCLC therapy.

Methods

We adopted three different methods: TEM, NTA and western blot analysis to characterize the cell‐derived exosomes from NCI‐H69 SCLC cell line and normal bronchial epithelial BEAS‐2B cell line. we next explored the effects of these exosomes on HUVE cell proliferation and migration in vitro.To verify sFlt‐1‐loaded exosomes suppress the tumor growth in vivo,we established subcutaneous xenografts in nude mice using the NCI‐H69 cell line.

Results

We observed that NCI‐H69‐exo significantly increased human umbilical vein endothelial cells (HUVEC) migration compared to BEAS‐2B‐exo in vitro and in vivo. sFlt‐1 protein expression was statistically higher in BEAS‐2B‐exo than NCI‐H69‐exo. sFlt‐1 protein or sFlt‐1‐enriched exosomes can inhibit the migration of HUVECs. Furthermore, sFlt‐1‐enriched exosomes exhibited higher inhibition efficacy on pro‐angiogenesis of NCI‐H69‐exo in comparison with the same concentration of sFlt‐1 protein. Intriguingly, sFlt‐1‐loaded exosomes showed marked anti‐tumor activity by inhibiting the growth of NCI‐H69 tumor xenografts. CD31 staining revealed that sFlt‐1‐loaded exosomes significantly reduced the vascular density of experimental mice. sFlt‐1‐loaded exosomes markedly induced tumor apoptosis and inhibited tumor cell proliferation in mice.

Conclusion

Exosomes from a SCLC cell line contain low levels of sFlt‐1 and significantly increased the migration of HUVECs. SFlt‐1‐enriched exosomes can inhibit NCI‐H69‐exo‐induced HUVEC migration. Exosomes enriched in sFlt‐1 have the potential to be effective therapeutic agents for SCLC.

DLL3: an emerging target in small cell lung cancer

Small cell lung cancer (SCLC) accounts for approximately 15% of all lung cancers. Despite high rates of response to first-line chemotherapy and radiotherapy, patients with extensive-stage disease eventually relapse, and very few patients survive more than 5 years from diagnosis. Treatment options for recurrent or refractory disease are limited, and the treatments that do exist are associated with significant treatment-related toxicities. Delta-like ligand 3 (DLL3) is an inhibitory Notch ligand that is highly expressed in SCLC and other neuroendocrine tumors but minimally expressed in normal tissues. It is therefore being explored as a potential therapeutic target in SCLC. Here, we review the preclinical and clinical evidence for targeting DLL3 in SCLC and discuss several DLL3-specific therapies being developed for the treatment of SCLC: the antibody-drug conjugate rovalpituzumab tesirine, the bispecific T cell engager immuno-oncology therapy AMG 757, and the chimeric antigen receptor T cell therapy AMG 119.

A metabolomic perspective of pazopanib-induced acute hepatotoxicity in mice

To elucidate the metabolism of pazopanib, a metabolomics approach was performed based on ultra-performance liquid chromatography coupled with electrospray ionization quadrupole mass spectrometry. A total of 22 pazopanib metabolites were identified in vitro and in vivo. Among these metabolites, 17 were novel, including several cysteine adducts and aldehyde derivatives. By screening using recombinant CYPs, CYP3A4 and CYP1A2 were found to be the main forms involved in the pazopanib hydroxylation. Formation of a cysteine conjugate (M3), an aldehyde derivative (M15) and two N-oxide metabolites (M18 and M20) from pazopanib could induce the oxidative stress that may be responsible in part for pazopanib-induced hepatotoxicity. Morphological observation of the liver suggested that pazopanib (300 mg/kg) could cause liver injury. The aspartate transaminase and alanine aminotransferase in serum significantly increased after pazopanib (150, 300 mg/kg) treatment; this liver injury could be partially reversed by the broad-spectrum CYP inhibitor 1-aminobenzotriazole (ABT). Metabolomics analysis revealed that pazopanib could significantly change the levels of L-carnitine, proline and lysophosphatidylcholine 18:1 in liver. Additionally, drug metabolism-related gene expression analysis revealed that hepatic Cyp2d22 and Abcb1a (P-gp) mRNAs were significantly lowered by pazopanib treatment. In conclusion, this study provides a global view of pazopanib metabolism and clues to its influence on hepatic function.

Comparison and discussion of the treatment guidelines for small cell lung cancer

Small cell lung cancer (SCLC), which accounts for 15% to 17% of all lung cancers, is one of the leading causes of cancer-related death worldwide. More than 130 000 new diagnoses of SCLC and 100 000 deaths from the disease were estimated to have occurred in China in 2013. The existing guidelines of SCLC therapeutic principles differ by region. In recent years, new immunotherapy and targeted therapy treatments have been lacking. In order to understand the current status of SCLC treatment in more detail, we identified the similarities and differences among the latest National Comprehensive Cancer Network Clinical Practice Guidelines for SCLC, the Chinese Society of Clinical Oncology Lung Cancer Guidelines, and the European Society for Medical Oncology Clinical Practice Guidelines for Metastatic SCLC, and present a reference of treatment strategies that should prove beneficial for the treatment of patients with SCLC.

Discovery of Novel Pazopanib-Based HDAC and VEGFR Dual Inhibitors Targeting Cancer Epigenetics and Angiogenesis Simultaneously

Herein a novel series of pazopanib hybrids as polypharmacological antitumor agents were developed based on the crosstalk between histone deacetylases (HDACs) and vascular endothelial growth factor (VEGF) pathway. Among them, one ortho-aminoanilide 6d and one hydroxamic acid 13f exhibited considerable total HDACs and VEGFR-2 inhibitory activities. The HDAC inhibitory activities endowed 6d and 13f with potent antiproliferative activities, which was not observed in the approved VEGFR inhibitor pazopanib. Compounds 6d and 13f possessed comparable HDAC isoform selectivity profiles to the clinical class I HDAC inhibitor MS-275 and the approved pan-HDAC inhibitor SAHA, respectively. 6d and 13f also exhibited uncompromised multiple tyrosine kinases inhibitory activities relative to pazopanib. The intracellular dual inhibition to HDAC and VEGFR of 6d and 13f was validated by Western blot analysis. In both HUVECs tube formation assay and rat thoracic aorta rings assay, 6d and 13f showed comparable antiangiogenic potencies to pazopanib. What's more, 6d possessed desirable pharmacokinetic profiles with the oral bioavailability of 72% in SD rats and considerable in vivo antitumor efficacy in a human colorectal adenocarcinoma (HT-29) xenograft model.

Managing Patients With Relapsed Small-Cell Lung Cancer

Despite high response rates to initial therapy, relapses are common in patients with small-cell lung cancer (SCLC). Systemic therapy after first-line failure remains important in the treatment paradigm of SCLC. Reinitiation of a previously administered first-line chemotherapy regimen is recommended for relapse > 6 months from completion of initial therapy. For relapse ≤ 6 months of initial therapy, sequential therapy with single agents is recommended. Clinical trial enrollment should be considered at all stages of treatment of SCLC. This review highlights the available treatment options in relapsed SCLC. In particular, we focus on prospective clinical trials demonstrating activity for the most commonly used agents in this setting. We end with a discussion on future directions and emerging targets with potential to improve outcomes in relapsed SCLC.

Current and future therapeutic approaches for the treatment of small cell lung cancer

INTRODUCTION

Small-cell lung cancer (SCLC) is a very aggressive disease characterized by a high response rate to first-line chemotherapy, but most patients relapse within 1 year with disappointing results to second-line treatments. Chemotherapy has reached a plateau of effectiveness and new therapeutic strategies are needed to change the natural history of SCLC. Areas covered: This review will focus on the current results and the future development of the therapeutic approaches for the treatment of SCLC. Expert commentary: Immunotherapy is becoming a new frontier for the management of SCLC with preliminary interesting results. To date, no targeted drugs have been approved for clinical practice but several novel agents are in an advanced stage of clinical development in SCLC.

Dynamic changes of phenotypically different circulating tumor cells sub-populations in patients with recurrent/refractory small cell lung cancer treated with pazopanib

The aim of the study was to investigate the effect of 2^nd-line pazopanib on the different CTCs subpopulations in SCLC patients and evaluate the clinical relevance of their changes. Different CTCs subpopulations were evaluated before pazopanib initiation (n = 56 patients), after one-cycle (n = 35) and on disease progression (n = 45) by CellSearch and double immunofluorescence using anti-CKs and anti-Ki67, anti-M30 or anti-Vimentin antibodies. Before treatment, CTCs were detected in 50% of patients by CellSearch whereas 53.4%, 15.5% and 74.1% patients had CK⁺/Ki67⁺, CK⁺/M30⁺ and CK⁺/Vim⁺ CTCs, respectively. One pazopanib cycle significantly decreased the number of CTCs as detected by CellSearch (p = 0.043) as well as the number of CK⁺/Ki67⁺ (p < 0.001), CK⁺/M30⁺ (p = 0^.015) and CK⁺/Vim⁺ (p < 0^.001) cells. On disease progression, both the incidence and CTC numbers were significantly increased (CellSearch, p = 0.027; CK⁺/Ki67⁺, p < 0.001; CK^+/M30⁺, p = 0.001 and CK⁺/Vim⁺, p < 0^.001)^. In multivariate analysis, the detection of CK⁺/Vim⁺ CTCs after one treatment cycle (HR: 7.9, 95% CI: 2.9–21.8; p < 0.001) and CTCs number on disease progression, as assessed by CellSearch, (HR: 2.0, 95% CI: 1.0–6.0; p = 0.005) were emerged as independent factors associated with decreased OS. In conclusion, pazopanib can eliminate different CTC subpopulations in patients with relapsed SCLC. The analysis of CTCs could be used as a dynamic biomarker of treatment efficacy.