Update on new drugs in small cell lung cancer

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.

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.

Chemical Reactivity Window Determines Prodrug Efficiency toward Glutathione Transferase Overexpressing Cancer Cells

Glutathione transferases (GSTs) are often overexpressed in tumors and frequently correlated to bad prognosis and resistance against a number of different anticancer drugs. To selectively target these cells and to overcome this resistance we previously have developed prodrugs that are derivatives of existing anticancer drugs (e.g., doxorubicin) incorporating a sulfonamide moiety. When cleaved by GSTs, the prodrug releases the cytostatic moiety predominantly in GST overexpressing cells, thus sparing normal cells with moderate enzyme levels. By modifying the sulfonamide it is possible to control the rate of drug release and specifically target different GSTs. Here we show that the newly synthesized compounds, 4-acetyl-2-nitro-benzenesulfonyl etoposide (ANS-etoposide) and 4-acetyl-2-nitro-benzenesulfonyl doxorubicin (ANS-DOX), function as prodrugs for GSTA1 and MGST1 overexpressing cell lines. ANS-DOX, in particular, showed a desirable cytotoxic profile by inducing toxicity and DNA damage in a GST-dependent manner compared to control cells. Its moderate conversion of 500 nmol/min/mg, as catalyzed by GSTA1, seems hereby essential since the more reactive 2,4-dinitrobenzenesulfonyl doxorubicin (DNS-DOX) (14000 nmol/min/mg) did not display a preference for GSTA1 overexpressing cells. DNS-DOX, however, effectively killed GSTP1 (20 nmol/min/mg) and MGST1 (450 nmol/min/mg) overexpressing cells as did the less reactive 4-mononitrobenzenesulfonyl doxorubicin (MNS-DOX) in a MGST1-dependent manner (1.5 nmol/min/mg) as shown previously. Furthermore, we show that the mechanism of these prodrugs involves a reduction in GSH levels as well as inhibition of the redox regulatory enzyme thioredoxin reductase 1 (TrxR1) by virtue of their electrophilic sulfonamide moiety. TrxR1 is upregulated in many tumors and associated with resistance to chemotherapy and poor patient prognosis. Additionally, the prodrugs potentially acted as a general shuttle system for DOX, by overcoming resistance mechanisms in cells. Here we propose that GST-dependent prodrugs require a conversion rate "window" in order to selectively target GST overexpressing cells, while limiting their effects on normal cells. Prodrugs are furthermore a suitable system to specifically target GSTs and to overcome various drug resistance mechanisms that apply to the parental drug.

Squamous non-small cell lung cancer as a distinct clinical entity

Traditionally, the treatment of lung cancer has been based on histologic type [non-small cell lung cancer (NSCLC) or small cell lung cancer], performance status, and stage of disease. However, more recently, treatment decisions are being made based on molecular and histologic characteristics of the tumor. Specifically, the subclassification of NSCLC as squamous or nonsquamous is important in the context of newer treatments because clinical data have demonstrated differences in the tolerability and activity of these agents. Although progress continues to be made in the treatment of nonsquamous NSCLC, a significant unmet need exists for patients with squamous NSCLC. For both targeted and chemotherapeutic agents, the majority of regulatory approvals and updates to clinical practice guidelines for advanced NSCLC have focused on nonsquamous disease. In addition, because of safety concerns, patients with squamous NSCLC have been excluded from a number of clinical trials of investigational agents, particularly those targeting angiogenesis. This review discusses the importance of histology for treatment selection in NSCLC and summarizes recently completed and ongoing trials of investigational agents in squamous NSCLC. In addition, exciting developments in next-generation sequencing of squamous NSCLC have highlighted differences between squamous and nonsquamous disease and revealed potential new therapeutic targets. Advances in the molecular genetics of squamous NSCLC and implications for therapy will also be reviewed. Although progress in squamous NSCLC has faced limitations, momentum is building toward the identification of more effective treatments for this patient population.

Poly (ADP) ribose polymerase enzyme inhibitor, veliparib, potentiates chemotherapy and radiation in vitro and in vivo in small cell lung cancer

Poly (ADP) ribose polymerase (PARP) plays a key role in DNA repair and is highly expressed in small cell lung cancer (SCLC). We investigated the therapeutic impact of PARP inhibition in SCLC. In vitro cytotoxicity of veliparib, cisplatin, carboplatin, and etoposide singly and combined was determined by MTS in 9 SCLC cell lines (H69, H128, H146, H526, H187, H209, DMS53, DMS153, and DMS114). Subcutaneous xenografts in athymic nu/nu mice of H146 and H128 cells with relatively high and low platinum sensitivity, respectively, were employed for in vivo testing. Mechanisms of differential sensitivity of SCLC cell lines to PARP inhibition were investigated by comparing protein and gene expression profiles of the platinum sensitive and the less sensitive cell lines. Veliparib showed limited single-agent cytotoxicity but selectively potentiated (≥50% reduction in IC₅₀) cisplatin, carboplatin, and etoposide in vitro in five of nine SCLC cell lines. Veliparib with cisplatin or etoposide or with both cisplatin and etoposide showed greater delay in tumor growth than chemotherapy alone in H146 but not H128 xenografts. The potentiating effect of veliparib was associated with in vitro cell line sensitivity to cisplatin (CC = 0.672; P = 0.048) and DNA-PKcs protein modulation. Gene expression profiling identified differential expression of a 5-gene panel (GLS, UBEC2, HACL1, MSI2, and LOC100129585) in cell lines with relatively greater sensitivity to platinum and veliparib combination. Veliparib potentiates standard cytotoxic agents against SCLC in a cell-specific manner. This potentiation correlates with platinum sensitivity, DNA-PKcs expression and a 5-gene expression profile.

Targeting small cell lung cancer harboring PIK3CA mutation with a selective oral PI3K inhibitor PF-4989216

PURPOSE

Constitutive activation of phosphoinositide 3-kinase (PI3K) occurs frequently in many human tumors via either gene mutation in the p110α catalytic subunit of PI3K or functional loss of tumor suppressor PTEN. Patients with small-cell lung cancer (SCLC) have very poor prognosis and survival rates such that an effective targeted therapy is in strong demand for these patients. In this study, we characterized the highly selective oral PI3K inhibitor, PF-4989216, in preclinical SCLC models to investigate whether targeting the PI3K pathway is an effective targeted therapy option for SCLCs that harbor a PIK3CA mutation.

EXPERIMENTAL DESIGN

A panel of SCLC cell lines with PIK3CA mutation or PTEN loss were treated with PF-4989216 in several in vitro assays, including PI3K pathway signaling, cell viability, apoptosis, cell-cycle progression, and cell transformation. SCLC cell lines that were sensitive in vitro to PF-4989216 were further evaluated by in vivo animal studies to determine the pharmacokinetic/pharmacodynamic relationship and tumor growth inhibition (TGI) by PF-4989216 treatment.

RESULTS

PF-4989216 inhibited PI3K downstream signaling and subsequently led to apoptosis induction, and inhibition in cell viability, transformation, and xenograft tumor growth in SCLCs harboring PIK3CA mutation. In SCLCs with PTEN loss, PF-4989216 also inhibited PI3K signaling but did not induce BCL2-interacting mediator (BIM)-mediated apoptosis nor was there any effect on cell viability or transformation. These results implicate differential tumorigenesis and apoptosis mechanisms in SCLCs harboring PIK3CA mutation versus PTEN loss.

CONCLUSIONS

Our results suggest that PF-4989216 is a potential cancer drug candidate for patients with SCLC with PIK3CA mutation but not PTEN loss.

Contribution of tumoral and host solute carriers to clinical drug response

Members of the solute carrier family of transporters are responsible for the cellular uptake of a broad range of endogenous compounds and xenobiotics in multiple tissues. Several of these solute carriers are known to be expressed in cancer cells or cancer cell lines, and decreased cellular uptake of drugs potentially contributes to the development of resistance. As result, the expression levels of these proteins in humans have important consequences for an individual's susceptibility to certain drug-induced side effects, interactions, and treatment efficacy. In this review article, we provide an update of this rapidly emerging field, with specific emphasis on the direct contribution of solute carriers to anticancer drug uptake in tumors, the role of these carriers in regulation of anticancer drug disposition, and recent advances in attempts to evaluate these proteins as therapeutic targets.

Paclitaxel plus bevacizumab in patients with chemoresistant relapsed small cell lung cancer as salvage treatment: a phase II multicenter study of the Hellenic Oncology Research Group

INTRODUCTION

Therapeutic options for patients with relapsed, chemo-resistant small-cell lung cancer (SCLC) are limited. Since paclitaxel has demonstrated single-agent activity in the second-line setting of SCLC and angiogenesis seems to play an important role in the pathogenesis of the disease, a phase II trial was conducted in order to evaluate the efficacy and the tolerance of their combination in patients with relapsed, chemo-resistant SCLC.

PATIENTS AND METHODS

Patients with an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 who experienced relapse within 3 months after completion of 1st line chemotherapy for SCLC were eligible. Patients were treated with paclitaxel (90 mg/m(2), days 1, 8 and 15) along with bevacizumab (10mg per kg of body weight, days 1 and 15) in cycles of 28 days.

RESULTS

Thirty patients (male/female: 27/3) with a median age of 64 years and ECOG performance status 0/1/2: 2/25/3 were enrolled. Nineteen patients (63.3%) had received at least two lines of prior treatment, 17 (56.7%) had undergone prior radiotherapy and nine (30%) had brain metastases at the time of study entry. The overall objective response rate was 20% (95% CI: 5.69-34.31%), including one complete remission, whereas the disease control rate was 36.7%. The median duration of response was 2.5 months (range, 1.5-5.7), the median progression-free survival 2.7 months (range, 0.5-9.2) and the median overall survival 6.3 months (range, 0.5-17.9). Grades 3 and 4 toxicities were limited in neutropenia, diarrhea and fatigue. There was one case of non-fatal pulmonary embolism.

CONCLUSIONS

The combination of paclitaxel with bevacizumab was feasible and active in this poor prognosis and heavily pretreated population of patients with advanced, chemoresistant SCLC, representing a valid therapeutic alternative which merits further evaluation.