Transitioning from molecular methods to therapeutic methods: An in‑depth analysis of glioblastoma (Review)

Glioblastoma (GBM) is the most aggressive primary brain tumour, characterised by high heterogeneity, aggressiveness and resistance to conventional therapies, leading to poor prognosis for patients. In recent years, with the rapid development of molecular biology and genomics technologies, significant progress has been made in understanding the molecular mechanisms of GBM. This has revealed a complex molecular network involving aberrant key signalling pathways, epigenetic alterations, interactions in the tumour microenvironment and regulation of non‑coding RNAs. Based on these molecular features, novel therapeutic strategies such as targeted therapies, immunotherapy and gene therapy are rapidly evolving and hold promise for improving the outcome of GBM. This review systematically summarises the advances in molecular mechanisms and therapeutic approaches for GBM. It aims to provide new perspectives for the precise diagnosis and personalised treatment of GBM, and to ultimately improve the prognosis of patients.

Harnessing Arsenic Derivatives and Natural Agents for Enhanced Glioblastoma Therapy

Glioblastoma (GBM) is the most common and lethal intracranial tumor in adults. Despite advances in the understanding of the molecular events responsible for disease development and progression, survival rates and mortality statistics for GBM patients have been virtually unchanged for decades and chemotherapeutic drugs used to treat GBM are limited. Arsenic derivatives, known as highly effective anticancer agents for leukemia therapy, has been demonstrated to exhibit cytocidal effects toward GBM cells by inducing cell death, cell cycle arrest, inhibition of migration/invasion, and angiogenesis. Differentiation induction of glioma stem-like cells (GSCs) and inhibition of neurosphere formation have also been attributed to the cytotoxicity of arsenic derivatives. Intriguingly, similar cytotoxic effects against GBM cells and GSCs have also been observed in natural agents such as anthocyanidins, tetrandrine, and bufadienolides. In the current review, we highlight the available data on the molecular mechanisms underlying the multifaceted anticancer activity of arsenic compounds and natural agents against cancer cells, especially focusing on GBM cells and GCSs. We also outline possible strategies for developing anticancer therapy by combining natural agents and arsenic compounds, as well as temozolomide, an alkylating agent used to treat GBM, in terms of improvement of chemotherapy sensitivity and minimization of side effects.

Advancements in Telomerase-Targeted Therapies for Glioblastoma: A Systematic Review

Glioblastoma (GBM) is a primary CNS tumor that is highly lethal in adults and has limited treatment options. Despite advancements in understanding the GBM biology, the standard treatment for GBM has remained unchanged for more than a decade. Only 6.8% of patients survive beyond five years. Telomerase, particularly the hTERT promoter mutations present in up to 80% of GBM cases, represents a promising therapeutic target due to its role in sustaining telomere length and cancer cell proliferation. This review examines the biology of telomerase in GBM and explores potential telomerase-targeted therapies. We conducted a systematic review following the PRISMA-P guidelines in the MEDLINE/PubMed and Scopus databases, from January 1995 to April 2024. We searched for suitable articles by utilizing the terms "GBM", "high-grade gliomas", "hTERT" and "telomerase". We incorporated studies addressing telomerase-targeted therapies into GBM studies, excluding non-English articles, reviews, and meta-analyses. We evaluated a total of 777 records and 46 full texts, including 36 studies in the final review. Several compounds aimed at inhibiting hTERT transcription demonstrated promising preclinical outcomes; however, they were unsuccessful in clinical trials owing to intricate regulatory pathways and inadequate pharmacokinetics. Direct hTERT inhibitors encountered numerous obstacles, including a prolonged latency for telomere shortening and the activation of the alternative lengthening of telomeres (ALT). The G-quadruplex DNA stabilizers appeared to be potential indirect inhibitors, but further clinical studies are required. Imetelstat, the only telomerase inhibitor that has undergone clinical trials, has demonstrated efficacy in various cancers, but its efficacy in GBM has been limited. Telomerase-targeted therapies in GBM is challenging due to complex hTERT regulation and inadequate inhibitor pharmacokinetics. Our study demonstrates that, despite promising preclinical results, no Telomerase inhibitors have been approved for GBM, and clinical trials have been largely unsuccessful. Future strategies may include Telomerase-based vaccines and multi-target inhibitors, which may provide more effective treatments when combined with a better understanding of telomere dynamics and tumor biology. These treatments have the potential to be integrated with existing ones and to improve the outcomes for patients with GBM.

Arsenic trioxide inhibits the functions of lung fibroblasts derived from patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic and fatal interstitial lung disease. Currently, no treatment can block or reverse the development of lung fibrosis in patients suffering from IPF. Recent studies indicate that arsenic trioxide (ATO), a safe, effective anti-cancer pro-oxidant drug, prevents the differentiation of normal human lung fibroblasts (NHLFs) in vitro and reduces experimental pulmonary fibrosis in vivo. In this context, we investigated the anti-fibrotic effects of ATO on the main fibrosis functions of human lung fibroblasts (HLFs) isolated from patients with IPF. IPF and non-IPF (control) HLFs were incubated with 0.01-1 μM ATO and stimulated with pro-fibrotic factors (PDGF-BB or TGF-β1). We measured their rates of proliferation, migration and differentiation and the cell stress response triggered by ATO. ATO did not affect cell viability but strongly inhibited the proliferation and migration of PDGF-BB-stimulated IPF and control HLFs. ATO also prevented myofibroblastic differentiation, as assessed by the expression of α-smooth muscle actin (α-SMA) and collagen-1, and the phosphorylation of SMAD2/3 in TGF-β1-stimulated HLFs. These antifibrotic effects were associated with increased expression of the transcription factor NRF2 and its target genes NQO1 and HMOX1. Genetic silencing of NRF2 inhibited the ATO-induced cell stress response but did not prevent the ATO-dependent inhibition of α-SMA expression in TGF-β1-stimulated HLFs. The results demonstrate that ATO, at concentrations similar to exposure in blood plasma of ATO-treated cancer patients, counteracted pro-fibrotic activities of HLFs from IPF patients. We propose to consider ATO for clinical exploration to define the therapeutic potential in patients with IPF.

The multifaceted NF-kB: are there still prospects of its inhibition for clinical intervention in pediatric central nervous system tumors?

Despite advances in the understanding of the molecular mechanisms underlying the basic biology and pathogenesis of pediatric central nervous system (CNS) malignancies, patients still have an extremely unfavorable prognosis. Over the years, a plethora of natural and synthetic compounds has emerged for the pharmacologic intervention of the NF-kB pathway, one of the most frequently dysregulated signaling cascades in human cancer with key roles in cell growth, survival, and therapy resistance. Here, we provide a review about the state-of-the-art concerning the dysregulation of this hub transcription factor in the most prevalent pediatric CNS tumors: glioma, medulloblastoma, and ependymoma. Moreover, we compile the available literature on the anti-proliferative effects of varied NF-kB inhibitors acting alone or in combination with other therapies in vitro, in vivo, and clinical trials. As the wealth of basic research data continues to accumulate, recognizing NF-kB as a therapeutic target may provide important insights to treat these diseases, hopefully contributing to increase cure rates and lower side effects related to therapy.

Arsenic trioxide in pediatric cancer - a case series and review of literature

Arsenic trioxide (ATO) has become an established component of treatment protocols for acute promyelocytic leukemia (APL) with excellent efficacy and no relevant sustained toxicity. Part of its action has been attributed to the inhibition of Hedgehog signaling (Hh) which enables a possible therapeutic approach as many pediatric tumor entities have been associated with increased Hh activity. We retrospectively analyzed 31 patients with refractory and relapsed pediatric cancer who were treated with ATO at the University Children's Hospital of Tuebingen. Additionally a literature review on the clinical and preclinical use of ATO in pediatric cancer treatment was performed.ATO alone as well as combinations with other drugs have proven effective in vitro and in mouse models of various pediatric malignancies. However, only few data on the clinical use of ATO in pediatric patients besides APL exist. In our patient sample, ATO was overall well tolerated in the treatment of various pediatric cancers, even in combination with other cytostatic drugs. Due to distinct tumor entities, differently progressed disease stages and varying co-medication, no clear statement can be made regarding the efficacy of ATO treatment. However, patients with proven Hh activation in molecular tumor profiling surpassed all other patients, who received ATO in an experimental treatment setting, in terms of survival. As molecular profiling of tumors increases and enhanced Hh activity can be detected at an early stage, ATO might expand its clinical use to other pediatric malignancies beyond APL depending on further clinical studies.

Autophagy as a Potential Therapy for Malignant Glioma

Glioma is the most frequent and aggressive type of brain neoplasm, being anaplastic astrocytoma (AA) and glioblastoma multiforme (GBM), its most malignant forms. The survival rate in patients with these neoplasms is 15 months after diagnosis, despite a diversity of treatments, including surgery, radiation, chemotherapy, and immunotherapy. The resistance of GBM to various therapies is due to a highly mutated genome; these genetic changes induce a de-regulation of several signaling pathways and result in higher cell proliferation rates, angiogenesis, invasion, and a marked resistance to apoptosis; this latter trait is a hallmark of highly invasive tumor cells, such as glioma cells. Due to a defective apoptosis in gliomas, induced autophagic death can be an alternative to remove tumor cells. Paradoxically, however, autophagy in cancer can promote either a cell death or survival. Modulating the autophagic pathway as a death mechanism for cancer cells has prompted the use of both inhibitors and autophagy inducers. The autophagic process, either as a cancer suppressing or inducing mechanism in high-grade gliomas is discussed in this review, along with therapeutic approaches to inhibit or induce autophagy in pre-clinical and clinical studies, aiming to increase the efficiency of conventional treatments to remove glioma neoplastic cells.

Arsenic trioxide and BIBR1532 synergistically inhibit breast cancer cell proliferation through attenuation of NF-κB signaling pathway

AIMS

Despite the remarkable anti-proliferative effects of Arsenic trioxide (ATO) in breast cancer cells, the requirement of high, toxic concentrations to induce apoptosis may cause serious side effects in patients. In the present study, we aimed to use BIBR1532, an hTERT inhibitor, in combination with ATO to sensitize MCF7 and MDA-231 cells to lower concentrations of ATO.

MAIN METHODS

Breast cancer cell lines MCF7 and MDA-231 were cultured and treated with different doses of ATO and BIBR1532 for 48 h and its effects on cell survival and proliferation were analyzed by MTT, crystal violet staining, colony formation assay, cell cycle, AnnexinV/PI and Real-time PCR tests.

KEY FINDINGS

ATO and BIBR1532 synergistically inhibited proliferation and colony-forming ability of breast cancer cells. Besides, BIBR1532 augmented ATO-induced cytotoxic effects via triggering G1 cell cycle arrest and induction of apoptosis coupled with the down-regulation of NF-κB target genes that were involved in cell cycle progression (e.g. CCND1 and CDK6) and prevention of apoptosis such as Bcl-2, Bcl-xl, c-IAP2, and Survivin Respectively. Moreover, ATO-BIBR1532 significantly reduced the mRNA expression level of RELA, NFKB1, and several validated target genes of the NF-κB signaling pathway including NFKBIA, VEGFC, c-Myc, and hTERT.

SIGNIFICANCE

The combination of ATO and BIBR1532 synergistically induced its anti-proliferative effect in breast cancer cells by targeting the two key cancer-related pathways, hTERT and NF-κB, and disrupting their feed-forward loop at the same time which result in the reduction of NF-κB transcriptional activity and subsequent down-regulation of its target genes.

Trace Elements in Human Nutrition (II) - An Update

The dietary requirement for an essential trace element is an intake level which meets a specified criterion for adequacy and thereby minimizes risk of nutrient deficiency or excess. Disturbances in trace element homeostasis may result in the development of pathologic states and diseases. This article is an update of a review article "Trace Elements in Human Nutrition-A Review" previously published in 2013. The previous review was updated to emphasis in detail the importance of known trace elements so far in humans' physiology and nutrition and also to implement the detailed information for practical and effective management of trace elements' status in clinical diagnosis and health care situations. Although various classifications for trace elements have been proposed and may be controversial, this review will use World Health Organization( WHO) classification as previously done. For this review a traditional integrated review format was chosen and many recent medical and scientific literatures for the new findings on bioavailability, functions, and state of excess/deficiency of trace elements were assessed. The results indicated that for the known essential elements, essentiality and toxicity are unrelated and toxicity is a matter of dose or exposure. Little is known about the essentiality of some of the probably essential elements. In regard to toxic heavy metals, a toxic element may nevertheless be essential. In addition, the early pathological manifestations of trace elements deficiency or excess are difficult to detect until more specific pathologically relevant indicators become available. Discoveries and many refinements in the development of new techniques and continual improvement in laboratory methods have enabled researchers to detect the early pathological consequences of deficiency or excess of trace elements. They all are promises to fulfill the gaps in the present and future research and clinical diagnosis of trace elements deficiencies or intoxications. However, further investigations are needed to complete the important gaps in our knowledge on trace elements, especially probably essential trace elements' role in health and disease status.

Arsenic trioxide induces the apoptosis and decreases NF-κB expression in lymphoma cell lines

Lymphoma is a type of cancer that develops from certain immune system cells. Arsenic trioxide (ATO) has attracted wide attention owing to its antitumor activities. However, the role of ATO in tumorigenesis and progression remains to be investigated. In the present study, the antitumor function of ATO was investigated in in lymphoma Raji and Jurkat cell lines and the effect of ATO on nuclear factor (NF)-κB expression levels. A Cell Counting kit-8 assay was used to assess cellular proliferation and the degree of cell apoptosis was measured by flow cytometric analysis; these assays demonstrated that ATO inhibited proliferation and promoted the apoptosis of Raji and Jurkat cells in a dose- and time-dependent manner. Western blot analysis revealed that ATO treatment affected the expression of apoptosis-associated proteins by downregulating the anti-apoptotic protein B-cell lymphoma-2 (Bcl-2) and upregulating the pro-apoptotic protein Bcl-2-associatedX and the degree of caspase-3 cleavage. In addition, reverse transcription-quantitative polymerase chain reaction and western blot analysis showed that the mRNA and protein expression levels of NF-κB were downregulated significantly following treatment with 2 µM ATO for 24, 48 and 72 h in the two cell lines. Additionally, immunofluorescence staining indicated that NF-κB expression diminished following ATO treatment in a time-dependent manner. These data indicated that ATO inhibited the proliferation of lymphoma cells by inducing cell apoptosis, which may be associated with the inhibition of the NF-κB signaling pathway. The findings of the present study may lay the foundation for developing a personalized medicine strategy using ATO via targeting of the NF-κB signaling pathway in lymphoma.

Enhanced cytotoxic effects of arsenite in combination with anthocyanidin compound, delphinidin, against a human leukemia cell line, HL-60

Among five major anthocyanin compounds, delphinidin exhibited the most potent and selective cytocidal effect against HL-60, a trivalent arsenic (As(III))-resistant cell line. Co-treatment with delphinidin and As(III) resulted in the reduction of IC₅₀ value for As(III) from 11.2 to 1.5 μM, which was considered as clinically achieved concentrations of As(III). The combination treatment strongly preferred to selectively enhance the cytotoxicity of As(III) against HL-60 cells rather than human peripheral blood mononuclear cells. The induction of apoptosis as evidenced by the increase of sub-G₁ cells, DNA fragmentation, annexin V-positive cells and the activation of caspase-8, -9 and -3 was observed in HL-60 cells co-treated with As(III) and delphinidin. Similar to the activation pattern of caspases, a substantial decrease in the expression level of Bid along with the loss of mitochondrial membrane potential was also observed. These results suggested that the combination treatment triggered a convergence of the intrinsic and extrinsic pathways of apoptosis via the activation of caspase-8 and cleaved Bid. Delphinidin itself significantly decreased the intracellular GSH ([i]GSH) and nuclear factor-κB (NF-κB) binding activity, and further returned As(III)-triggered increment of [i]GSH and enhancement of NF-κB binding activity to control level. Additionally, buthionine sulfoximine, a GSH depletor; JSH-23, a NF-κB inhibitor, also mimicked the capacity of delphinidin to significantly induce the reduction of [i]GSH along with the potentiation of As(III) cytotoxicity in HL-60 cells. These observations suggested that delphinidin-induced sensitization of HL-60 cells to As(III) was caused by the reduction of [i]GSH, which was probably associated with the inhibitory effect of delphinidin on NF-κB binding activity. These findings further suggest that delphinidin-induced sensitization of HL-60 cells to As(III) may lead to dose reduction of As(III) in clinical application, and ultimately contribute to minimizing its side effects.

Blockade of JAK2/STAT3 intensifies the anti-tumor activity of arsenic trioxide in acute myeloid leukemia cells: Novel synergistic mechanism via the mediation of reactive oxygen species

Reactive oxygen species (ROS) are essential mediators of crucial cellular processes including apoptosis, proliferation, survival and cell cycle. Their regulatory role in cancer progression has seen in different human malignancies such as acute myeloid leukemia (AML). AML patients suffer from high resistance of the tumors against routine therapeutics including ATO. ATO enhance reactive oxygen species levels and induce apoptosis and suppresses proliferation in AML cells. However, some pathways such as JAK2/STAT3 ease anti-tumor activity of ATO by reducing reactive oxygen species amount and protecting the cell from apoptosis. In the present study, we use ruxolitinib (potent JAK2 inhibitor) to increase the sensitivity of AML cells to ATO treatment. We test, the effect of this combination on metabolic activity, proliferation, colony formation, cell cycle distribution, apoptosis, oxidative stress and DNA damage. Our results showed that combination of ATO with ruxolitinib synergistically reduced metabolic activity, proliferation and survival of AML cell lines. This combination induced G1/S cell cycle arrest because of reactive oxygen species elevation and GSH reduction. Besides, enhancement of reactive oxygen species increased apoptosis rate in combination samples. We uncovered that the synergistic anti-tumor effect of ATO and ruxolitinib in AML cells mediates via reactive oxygen species elevation and DNA damage. Overall, our results show that the combinatorial therapy of AML cells is more effective than solo-targeted therapy.

Suppression of IKK, but not activation of p53 is responsible for cell death mediated by naturally occurring oxidized tetranortriterpenoid

Tetranortriterpenoids (limonoids) obtained from the neem tree (Azadirachta indica) have gained significant attention due to their anti-proliferative properties. Here we are investigating the role of a highly oxidized tetranortriterpenoid, azadirachtin on induction of the cell death. Using various apoptotic assays, we show that azadirachtin induces cell death independent of cell types. Although azadirachtin-treated cells show increased expression of p53, but no phosphorylation of p53 (at Ser15 and Ser46) is detected. In silico analysis reveals that azadirachtin interacts with Mdm2 in the p53 binding site, postulating the mutually exclusive interaction of p53 and azadirachtin with Mdm2. Surprisingly, azadirachtin potentiates cell death efficiently in both p53 wild-type and p53 negative cells. In addition, we find azadirachtin suppresses nuclear transcription factor kappaB (NF-κB) by inhibiting the phosphorylation of upstream inhibitory subunit of NF-κB (IκB) kinase (IKK). Further, azadirachtin is unable to potentiate apoptosis in NF-κB-downregulated (IκB-DN) cells, whereas ectopic expression of p65 rescues azadirachtin-mediated apoptosis, regardless of their p53 status. Hence, our data suggest that azadirachtin mediates cell death through inhibition of NF-κB, but not due to the activation of p53. In conclusion, this study proposes azadirachtin as a potential therapeutic agent where insensitivity toward chemotherapy occurs due to the inactivation or mutations in p53.

Arsenic trioxide-mediated suppression of miR-182-5p is associated with potent anti-oxidant effects through up-regulation of SESN2

Arsenic trioxide (ATO) is a traditional Chinese medicine that can induce oxidative stress for treatment of cancer cells. However, ATO may generate anti-oxidative responses to compromise the cytotoxic effect, but the underlying mechanisms remain unclear. Here we found that ATO could inhibit miR-182-5p expression in patient-derived primary S1 glioblastoma (GBM) cells accompanied by up-regulation of Sestrin-2 (SESN2) mRNA, a known anti-oxidant molecule. This phenomenon was also detected in a U87MG glioma cell line, human lung adenocarcinoma H1299 cell line and A549 cell line. Pretreatment with a free radical scavenger N-acetylcysteine (NAC) reduced the oxidative stress induced by ATO. Concomitantly, ATO mediated suppression of miR-182-5p and enhancement of SESN2 expression were also compromised. The MTT assay further showed that ATO induced cytotoxicity was enhanced by transfection of miR-182-5p mimics. Overexpression of miR-182-5p mimics significantly suppressed the expression of SENS2 and a firefly luciferase reporter gene fused to 3’- untranslated region (UTR) of SESN2 mRNA. Use of ribonucleoprotein immunoprecipitation (RNP-IP), ATO mediated suppression of miR-182-5p led to the stabilization of SESN2 mRNA as a result of Argonaute-2 (AGO2) dependent gene silencing. Furthermore, high expression of miR-182-5p and low expression of SESN2 mRNA tend to be associated with longer survival of glioma or lung cancer patients using public available gene expression datasets and online tools for prediction of clinical outcomes. Taken together, current data suggest that the miR-182-5p/SENS2 pathway is involved in ATO induced anti-oxidant responses, which may be important for the design of novel strategy for cancer treatment.

Multifactorial Modes of Action of Arsenic Trioxide in Cancer Cells as Analyzed by Classical and Network Pharmacology

Arsenic trioxide is a traditional remedy in Chinese Medicine since ages. Nowadays, it is clinically used to treat acute promyelocytic leukemia (APL) by targeting PML/RARA. However, the drug's activity is broader and the mechanisms of action in other tumor types remain unclear. In this study, we investigated molecular modes of action by classical and network pharmacological approaches. CEM/ADR5000 resistance leukemic cells were similar sensitive to As2O3 as their wild-type counterpart CCRF-CEM (resistance ratio: 1.88). Drug-resistant U87.MG ΔEGFR glioblastoma cells harboring mutated epidermal growth factor receptor were even more sensitive (collateral sensitive) than wild-type U87.MG cells (resistance ratio: 0.33). HCT-116 colon carcinoma p53-/- knockout cells were 7.16-fold resistant toward As2O3 compared to wild-type cells. Forty genes determining cellular responsiveness to As2O3 were identified by microarray and COMPARE analyses in 58 cell lines of the NCI panel. Hierarchical cluster analysis-based heat mapping revealed significant differences between As2O3 sensitive cell lines and resistant cell lines with p-value: 1.86 × 10-5. The genes were subjected to Galaxy Cistrome gene promoter transcription factor analysis to predict the binding of transcription factors. We have exemplarily chosen NF-kB and AP-1, and indeed As2O3 dose-dependently inhibited the promoter activity of these two transcription factors in reporter cell lines. Furthermore, the genes identified here and those published in the literature were assembled and subjected to Ingenuity Pathway Analysis for comprehensive network pharmacological approaches that included all known factors of resistance of tumor cells to As2O3. In addition to pathways related to the anticancer effects of As2O3, several neurological pathways were identified. As arsenic is well-known to exert neurotoxicity, these pathways might account for neurological side effects. In conclusion, the activity of As2O3 is not restricted to acute promyelocytic leukemia. In addition to PML/RARA, numerous other genes belonging to diverse functional classes may also contribute to its cytotoxicity. Network pharmacology is suited to unravel the multifactorial modes of action of As2O3.

Regulation of ABCG2 by nuclear factor kappa B affects the sensitivity of human lung adenocarcinoma A549 cells to arsenic trioxide

Arsenic trioxide (As₂O₃) is successfully used as an anticancer agent against acute promyelocytic leukemia and some solid tumors. However, the application of As₂O₃ is largely limited by its drug resistance in the treatment of non-small cell lung carcinoma (NSCLC). Therefore, it is an urgent task to enhance the sensitivity of lung cancer cells to As₂O₃. In this study, using human lung adenocarcinoma A549 cells as a cell culture model, we demonstrated that an adenosine triphosphate binding cassette (ABC) transporter, ABCG2, was significantly increased by As₂O₃ treatment, while other ABC transporters, ABCB1 and ABCC1 showed no remarkable change in the response to As₂O₃. After inhibition of ABCG2 by its specific inhibitor, the drug sensitivity of As₂O₃ to A549 cells was significantly enhanced, manifested by decreased cell viability and colony formation as well as the increased ROS production and cell apoptosis. To further understand the molecular mechanism underlying the elevation of ABCG2 expression in As₂O₃-treated cells, we detected the activation state of nuclear factor kappa B (NF-κB) pathway and its relationship with ABCG2 expression. Our results revealed that the increased expression of ABCG2 was regulated by NF-κB, and thus affecting the cell death of As₂O₃-treated A549 cells. These findings indicate that inhibition of NF-κB/ABCG2 pathway by specific inhibitors may be a new strategy for the improvement of As₂O₃ sensitivity in NSCLC treatment.