Phenformin inhibits growth and epithelial-mesenchymal transition of ErbB2-overexpressing breast cancer cells through targeting the IGF1R pathway

Metformin and long non-coding RNAs in breast cancer

Breast cancer (BC) is the second most common cancer and cause of death in women. In recent years many studies investigated the association of long non-coding RNAs (lncRNAs), as novel genetic factors, on BC risk, survival, clinical and pathological features. Recent studies also investigated the roles of metformin treatment as the firstline treatment for type 2 diabetes (T2D) played in lncRNAs expression/regulation or BC incidence, outcome, mortality and survival, separately. This comprehensive study aimed to review lncRNAs associated with BC features and identify metformin-regulated lncRNAs and their mechanisms of action on BC or other types of cancers. Finally, metformin affects BC by regulating five BC-associated lncRNAs including GAS5, HOTAIR, MALAT1, and H19, by several molecular mechanisms have been described in this review. In addition, metformin action on other types of cancers by regulating ten lncRNAs including AC006160.1, Loc100506691, lncRNA-AF085935, SNHG7, HULC, UCA1, H19, MALAT1, AFAP1-AS1, AC026904.1 is described.

Metformin and Cancer, an Ambiguanidous Relationship

The deregulation of energetic and cellular metabolism is a signature of cancer cells. Thus, drugs targeting cancer cell metabolism may have promising therapeutic potential. Previous reports demonstrate that the widely used normoglycemic agent, metformin, can decrease the risk of cancer in type 2 diabetics and inhibit cell growth in various cancers, including pancreatic, colon, prostate, ovarian, and breast cancer. While metformin is a known adenosine monophosphate-activated protein kinase (AMPK) agonist and an inhibitor of the electron transport chain complex I, its mechanism of action in cancer cells as well as its effect on cancer metabolism is not clearly established. In this review, we will give an update on the role of metformin as an antitumoral agent and detail relevant evidence on the potential use and mechanisms of action of metformin in cancer. Analyzing antitumoral, signaling, and metabolic impacts of metformin on cancer cells may provide promising new therapeutic strategies in oncology.

Phenformin increases early hematopoietic progenitors in the Jak2V617F murine model

BACKGROUND

 Myeloproliferative neoplasms (MPN) are disorders characterized by an alteration at the hematopoietic stem cell (HSC) level, where the JAK2 mutation is the most common genetic alteration found in classic MPN (polycythemia vera, essential thrombocythemia, and primary myelofibrosis). We and others previously demonstrated that metformin reduced splenomegaly and platelets counts in peripheral blood in JAK2^V617F pre-clinical MPN models, which highlighted the antineoplastic potential of biguanides for MPN treatment. Phenformin is a biguanide that has been used to treat diabetes, but was withdrawn due to its potential to cause lactic acidosis in patients.

AIMS

We herein aimed to investigate the effects of phenformin in MPN disease burden and stem cell function in Jak2^V617F-knockin MPN mice.

RESULTS

In vitro phenformin treatment reduced cell viability and increased apoptosis in SET2 JAK2^V67F cells. Long-term treatment with 40 mg/kg phenformin in Jak2^V617F knockin mice increased the frequency of LSK, myeloid progenitors (MP), and multipotent progenitors (MPP) in the bone marrow. Phenformin treatment did not affect peripheral blood counts, spleen weight, megakaryocyte count, erythroid precursors frequency, or ex vivo clonogenic capacity. Ex vivo treatment of bone marrow cells from Jak2^V617F knockin mice with phenformin did not affect hematologic parameters or engraftment in recipient mice.

CONCLUSIONS

Phenformin increased the percentages of LSK, MP, and MPP populations, but did not reduce disease burden in Jak2^V617F-knockin mice. Additional studies are necessary to further understand the effects of phenformin on early hematopoietic progenitors.

Breast Cancer Cell Subtypes Display Different Metabolic Phenotypes That Correlate with Their Clinical Classification

Simple Summary

Recent studies on cancer cell metabolism have achieved notable breakthroughs that have led to a new scientific paradigm. How cancer cell metabolic reprogramming is orchestrated and the decisive role of this reprogramming in the oncogenic process and tumor adaptative evolution has been characterized at the molecular level. Despite this knowledge, it is essential to understand how cancer cells can metabolically respond as a living whole to ensure their survival and adaptation potential. In this work, we investigated whether different cancers and different subtypes display different metabolic phenotypes with a focus on breast cancer cell models representative of each clinical subtype. The potential results might have significant translational implications for diagnostic, prognostic and therapeutic applications.

Abstract

Metabolic reprogramming of cancer cells represents an orchestrated network of evolving molecular and functional adaptations during oncogenic progression. In particular, how metabolic reprogramming is orchestrated in breast cancer and its decisive role in the oncogenic process and tumor evolving adaptations are well consolidated at the molecular level. Nevertheless, potential correlations between functional metabolic features and breast cancer clinical classification still represent issues that have not been fully studied to date. Accordingly, we aimed to investigate whether breast cancer cell models representative of each clinical subtype might display different metabolic phenotypes that correlate with current clinical classifications. In the present work, functional metabolic profiling was performed for breast cancer cell models representative of each clinical subtype based on the combination of enzyme inhibitors for key metabolic pathways, and isotope-labeled tracing dynamic analysis. The results indicated the main metabolic phenotypes, so-called ‘metabophenotypes’, in terms of their dependency on glycolytic metabolism or their reliance on mitochondrial oxidative metabolism. The results showed that breast cancer cell subtypes display different metabophenotypes. Importantly, these metabophenotypes are clearly correlated with the current clinical classifications.

Phenformin synergistically sensitizes liver cancer cells to sorafenib by downregulating CRAF/ERK and PI3K/AKT/mTOR pathways

Sorafenib is a first-line drug to treat advanced hepatocellular carcinoma (HCC), which can prolong the median overall survival of patients by approximately 3 months. Phenformin is a biguanide derivative that has been shown to exhibit antitumor activity superior to that of metformin. We herein explored the ability of phenformin to enhance the anti-cancer activity of sorafenib against HCC and the mechanisms underlying such synergy. The Hep-G2 and SMMC-7721 HCC cell lines were treated with sorafenib and/or phenformin, after which the proliferation of these cells was evaluated via MTT and colony formation assays, while invasion and apoptotic cell death were evaluated via Transwell and flow cytometry assays, respectively. In addition, protein levels were assessed by Western blotting, drug synergy was assessed with the CompuSyn software, and xenograft models were established by implanting Hep-G2 cells into nude mice and then assessing drug antitumor efficacy. Sorafenib and phenformin exhibited a synergistic ability to suppress HCC cell proliferation, migration, and survival. Phenformin further bolstered the ability of sorafenib to inhibit the CRAF/ERK and PI3K/AKT/mTOR pathways. Strikingly, the combination of these two drugs achieved better in vivo efficacy in a murine model system, without causing significant weight loss or hepatorenal toxicity. Sorafenib and phenformin can synergistically suppress CRAF/ERK and PI3K/AKT/mTOR pathway activation in HCC cells, and may thus represent a promising approach to treating this deadly cancer.

Mitochondrial Inhibition: a Treatment Strategy in Cancer?

PURPOSE OF REVIEW

Mitochondria have a major impact on virtually all processes linked to oncogenesis. Thus, mitochondrial metabolism inhibition has emerged as a promising anticancer strategy. In this review, we discuss the anticancer potential of mitochondrial inhibitors, with particular focus on metformin, in the context of more effective, targeted therapeutic modalities, and diagnostic strategies for cancer patients.

RECENT FINDINGS

Metformin has gained interest as an antitumor agent. However, promising results have not been translated into remarkable advances in the clinical practice. Recent findings emphasize the need of providing a metabolic context in which mitochondrial inhibitors may elicit its anticancerous effects. In addition, mitochondria are critical regulators in orchestrating immune responses. Thus, the immunomodulatory effect of mitochondrial inhibitors should also be taken into account to optimize its clinical use. Targeting mitochondrial metabolic network represents a promising therapeutic strategy in cancer. However, there is a need to define the metabolic context in which mitochondrial inhibitors are more effective, as well as how the cross-talk between many immunological functions and mitochondrial functionality may be exploited for a therapeutic benefit in cancer patients.

Treatment of ErbB2 breast cancer by mitochondrial targeting

Background

ErbB2 breast cancer still remains an unmet need due to primary and/or acquired resistance to current treatment strategies. MEDICA compounds consist of synthetic long-chain α,ω-dicarboxylic acids previously reported to suppress breast cancer in PyMT transgenic mice.

Methods

MEDICA efficacy and mode of action in the ErbB2 context was studied in ErbB2 transgenic mice and human breast cancer cells.

Results

MEDICA treatment is shown here to suppress ErbB2 breast tumors and lung metastasis in ErbB2/neu MMTV transgenic mice, to suppress ErbB2/neu xenografts in nod/scid mice, and to suppress survival of AU565 and BT474 human ErbB2 breast cancer cells. Suppression of ErbB2 breast tumors by MEDICA is due to lipid raft disruption with loss of ErbB family members, including EGFR, ErbB2, and ErbB3. In addition, MEDICA inhibits mTORC1 activity, independently of abrogating the ErbB receptors and their signaling cascades. The double hit of MEDICA in abrogating ErbB and mTORC1 is partly accounted for by targeting mitochondria complex I.

Conclusions

Mitochondrial targeting by MEDICA suppresses ErbB2 breast tumors and metastasis due to lipid raft disruption and inhibition of mTORC1 activity. Inhibition of mTORC1 activity by MEDICA avoids the resistance acquired by canonical mTORC1 inhibitors like rapalogs or mTOR kinase inhibitors.

Buformin suppresses osteosarcoma via targeting AMPK signaling pathway

BACKGROUND

Buformin has been reported to be a powerful anticancer drug by activating the AMPK signal. Herein, we aimed to investigate the effects of buformin on osteosarcoma.

MATERIAL AND METHODS

Cellular proliferative abilities were determined by cell counting kit-8 and colony formation assays. Cellular invasion was investigated using a transwell system. Cell cycle was examined by flow cytometry. Western blot was performed to measure the expression of key proteins. Synergistic effects of buformin and cisplatin were validated in seven fresh osteosarcoma tissues.

RESULTS

Buformin suppressed the growth of U-2 OS cells in a dose-dependent manner (IC50 = 69.1 µM). Moreover, buformin induced cell cycle arrest (P < 0.001) and impaired cellular invasion (P = 0.038). Phosphorylation of AMPK was upregulated by buformin, while phosphorylation of S6, cyclin D1, and MMP9 were significantly downregulated. In addition, buformin notably induced accumulation of reactive oxygen species and lactate and eventually decreased ATP production. In both U-2 OS cells and the primary cultured osteosarcoma tissues, buformin increased tumor sensitivity to cisplatin.

CONCLUSIONS

Buformin could suppress tumor growth and invasion of osteosarcoma through directly targeting the AMPK signaling pathway. Moreover, buformin inhibited the abnormal metabolism and notably increased the cytotoxicity of cisplatin, and therefore represents a new potential treatment option for osteosarcoma.

Therapeutic aspects of AMPK in breast cancer: Progress, challenges, and future directions

Breast cancer is the most ubiquitous type of neoplasms among women worldwide. Molecular aberrations associated with breast development and progressions have been extensively investigated in recent years. An AMP-activated kinase (AMPK) initially identified as a cellular energy sensor that plays a crucial role in cellular energy homeostasis. Intensive research over the last decade about the molecular mechanisms of AMPK has demonstrated that AMPK mediated diverse biological functions are achieved through phosphorylation and regulation of multiple downstream signaling molecules in normal tissue. Downregulation of AMPK activity or decreased level involved in the promotion of breast tumorigenesis, and thus activation of AMPK found to oppose tumor progression. In this review, we epitomize the recent advances in exploring the tumor suppressor function of AMPK pathways. Besides, we discuss the developments in the area of AMPK activator and its molecular mechanisms for breast cancer treatment.

Redox Homeostasis and Metabolism in Cancer: A Complex Mechanism and Potential Targeted Therapeutics

Reactive Oxygen Species or "ROS" encompass several molecules derived from oxygen that can oxidize other molecules and subsequently transition rapidly between species. The key roles of ROS in biological processes are cell signaling, biosynthetic processes, and host defense. In cancer cells, increased ROS production and oxidative stress are instigated by carcinogens, oncogenic mutations, and importantly, metabolic reprograming of the rapidly proliferating cancer cells. Increased ROS production activates myriad downstream survival pathways that further cancer progression and metastasis. In this review, we highlight the relation between ROS, the metabolic programing of cancer, and stromal and immune cells with emphasis on and the transcription machinery involved in redox homeostasis, metabolic programing and malignant phenotype. We also shed light on the therapeutic targeting of metabolic pathways generating ROS as we investigate: Orlistat, Biguandes, AICAR, 2 Deoxyglucose, CPI-613, and Etomoxir.

Phenformin Attenuates Renal Injury in Unilateral Ureteral Obstructed Mice without Affecting Immune Cell Infiltration

Phenformin and metformin are antihyperglycemic drugs that belong to the class of biguanides. Previously, we demonstrated that metformin elicits renoprotective effects in unilateral ureteral obstructed mice by reducing the infiltration of immune cells into the kidney. Since phenformin is a more potent drug as compared to metformin, we investigated the renoprotective properties of phenformin. We studied the efficacy of both drugs using mice that underwent unilateral ureteral obstruction. Renal damage was evaluated on RNA and protein level by qPCR, Western blotting, and immunohistochemistry. Moreover, we studied immune cell infiltration using flow cytometry. Both biguanides significantly reduced UUO-induced kidney injury, as illustrated by a reduction in KIM-1 protein expression. In addition, both metformin and phenformin impacted the gene expression of several inflammatory markers but to a different extent. Moreover, in contrast to metformin, phenformin did not impact immune cell infiltration into UUO kidneys. In conclusion, we demonstrated that phenformin has similar renoprotective effects as metformin, but the mechanism of action differs, and phenformin is more potent. The beneficial effects of phenformin are probably due to inhibition of the STAT3 pathway and mitochondrial complex I. Further research is needed to unveil the therapeutic potential of phenformin for the treatment of renal injury, either at low, non-toxic concentrations or as part of a combination therapy.

The anti-cancer effects of phenformin in thyroid cancer cell lines and in normal thyrocytes

Phenformin is a biguanide drug which, besides the original anti-diabetic effect, also exerts anti-cancer effects. The aim of this study was to further characterize these latter in terms of both cell-viability and modulation of the secretion of the pro-tumorigenic chemokine CXCL8. Normal human thyrocytes in primary cultures (NHT) and thyroid cancer cell lines, TPC-1 and 8505C (RET/PTC and BRAFV600E mutated, respectively) were treated with increasing concentrations of phenformin at different times. Cell-viability was assessed by WST-1 and further characterized by AnnexinV/PI staining and cell proliferation colony-assay. CXCL8 levels were measured in cell supernatants. Phenformin reduced cell-viability in TPC-1 and 8505C and their ability to form colonies. In NHT cells, phenformin affected cell-viability only at the maximal dose but interestingly it inhibited CXCL8 secretion at all the concentrations not affecting cell-viability. Phenformin had no effect on CXCL8 secretion in thyroid cancer cell lines. Thus, phenformin exerts anti-cancer effects on both cancer cells (cell death induction) and surrounding normal cells (inhibition of CXCL8 secretion). These results highlight that the anti-cancer effects of phenformin are multifaceted and effective on both solid and soluble components of the tumor-microenvironment.

Dual Inhibition of Pirarubicin-Induced AKT and ERK Activations by Phenformin Sensitively Suppresses Bladder Cancer Growth

Activations of Akt or ERK pathway induced by clinical drugs promote therapeutic failure due to decrease of drug response, and no available strategies have been developed to solve these problems. In this study, we found that pirarubicin (THP), one important chemotherapeutic drug for treating bladder cancer intravesically, dramatically elevated phosphorylations of both Akt and Erk1/2 in addition to inducing DNA damage. MK2206 or AZD6244, representative Akt and Erk1/2 inhibitors, respectively, profoundly sensitized bladder cancer cells to THP treatment. Interestingly, we found that inhibition of a single arm of either Akt or Erk1/2 pathway would induce the increase of another arm, indicating the existence of the crosstalk between these two pathways. Thus, simultaneous suppression of both signals may be needed for increasing the sensitivity of THP. On the other hand, we revealed that phenformin efficiently inhibited both Akt and Erk1/2 phosphorylation in a dose-dependent manner. Furthermore, we demonstrated that phenformin, mimicking dual inhibitors, plays dramatically synergistic action with THP both in vitro and in vivo. Our findings suggest that combination therapy of THP with dual inhibitors may constitute a successful strategy for improving chemotherapy response.

Phenformin as an Anticancer Agent: Challenges and Prospects

Currently, there is increasing evidence linking diabetes mellitus (especially type 2 diabetes mellitus) with carcinogenesis through various biological processes, such as fat-induced chronic inflammation, hyperglycemia, hyperinsulinemia, and angiogenesis. Chemotherapeutic agents are used in the treatment of cancer, but in most cases, patients develop resistance. Phenformin, an oral biguanide drug used to treat type 2 diabetes mellitus, was removed from the market due to a high risk of fatal lactic acidosis. However, it has been shown that phenformin is, with other biguanides, an authentic tumor disruptor, not only by the production of hypoglycemia due to caloric restriction through AMP-activated protein kinase with energy detection (AMPK) but also as a blocker of the mTOR regulatory complex. Moreover, the addition of phenformin eliminates resistance to antiangiogenic tyrosine kinase inhibitors (TKI), which prevent the uncontrolled metabolism of glucose in tumor cells. In this review, we evidence the great potential of phenformin as an anticancer agent. We thoroughly review its mechanism of action and clinical trial assays, specially focusing on current challenges and future perspectives of this promising drug.

Bisphenol AF promotes estrogen receptor-positive breast cancer cell proliferation through amphiregulin-mediated crosstalk with receptor tyrosine kinase signaling

Exposure to bisphenol A (BPA), an endocrine-disrupting compound, is associated with increased risk of estrogen-related diseases, including estrogen receptor-positive (ER⁺) breast cancer. Although bisphenol analogs, i.e. bisphenol AF (BPAF), have replaced BPA in industrial settings, increasing data indicate that these alternatives may have similar or even more potent estrogenic effects. As such, BPAF exhibits increased ER binding affinities than BPA in biochemical assays. However, preclinical studies exploring the effects of BPAF on ER⁺ breast cancer are missing mechanistic data. Thus, we aimed to characterize the effects of BPAF on MCF-7 and T47D ER⁺ breast cancer cells with mechanistic insight. We found that BPAF promoted cell growth and cell cycle progression concurrently with BPAF-induced ERα transcriptional activity and ER-RTK signaling activation. ER signaling blockage revealed that BPAF-induced cell proliferation and ER-RTK crosstalk were ER-dependent. Gene expression data demonstrated that AREG is a sensitive target of BPAF in our in vitro models. Importantly, we determined that AREG upregulation is necessary for BPAF-induced cellular responses. Ultimately, our novel finding that AREG mediates BPAF-induced ER-RTK crosstalk in ER⁺ breast cancer cells supports future studies to characterize the impact of BPAF on human ER⁺ breast cancer risk and to assess the safety profile of BPAF.

Repurposed Biguanide Drugs in Glioblastoma Exert Antiproliferative Effects via the Inhibition of Intracellular Chloride Channel 1 Activity

The lack of in-depth knowledge about the molecular determinants of glioblastoma (GBM) occurrence and progression, combined with few effective and BBB crossing-targeted compounds represents a major challenge for the discovery of novel and efficacious drugs for GBM. Among relevant molecular factors controlling the aggressive behavior of GBM, chloride intracellular channel 1 (CLIC1) represents an emerging prognostic and predictive biomarker, as well as a promising therapeutic target. CLIC1 is a metamorphic protein, co-existing as both soluble cytoplasmic and membrane-associated conformers, with the latter acting as chloride selective ion channel. CLIC1 is involved in several physiological cell functions and its abnormal expression triggers tumor development, favoring tumor cell proliferation, invasion, and metastasis. CLIC1 overexpression is associated with aggressive features of various human solid tumors, including GBM, in which its expression level is correlated with poor prognosis. Moreover, increasing evidence shows that modification of microglia ion channel activity, and CLIC1 in particular, contributes to the development of different neuropathological states and brain tumors. Intriguingly, CLIC1 is constitutively active within cancer stem cells (CSCs), while it seems less relevant for the survival of non-CSC GBM subpopulations and for normal cells. CSCs represent GBM development and progression driving force, being endowed with stem cell-like properties (self-renewal and differentiation), ability to survive therapies, to expand and differentiate, causing tumor recurrence. Downregulation of CLIC1 results in drastic inhibition of GBM CSC proliferation in vitro and in vivo, making the control of the activity this of channel a possible innovative pharmacological target. Recently, drugs belonging to the biguanide class (including metformin) were reported to selectively inhibit CLIC1 activity in CSCs, impairing their viability and invasiveness, but sparing normal stem cells, thus representing potential novel antitumor drugs with a safe toxicological profile. On these premises, we review the most recent insights into the biological role of CLIC1 as a potential selective pharmacological target in GBM. Moreover, we examine old and new drugs able to functionally target CLIC1 activity, discussing the challenges and potential development of CLIC1-targeted therapies.

Repurposing old drugs in oncology: Opportunities with clinical and regulatory challenges ahead

WHAT IS KNOWN AND OBJECTIVE

In order to expedite the availability of drugs to treat cancers in a cost-effective manner, repurposing of old drugs for oncological indications is gathering momentum. Revolutionary advances in pharmacology and genomics have demonstrated many old drugs to have activity at novel antioncogenic pharmacological targets. We decided to investigate whether prospective studies support the promises of nonclinical and retrospective clinical studies on repurposing three old drugs, namely metformin, valproate and astemizole.

METHODS

We conducted an extensive literature search through PubMed to gather representative nonclinical and retrospective clinical studies that investigated the potential repurposing of these three drugs for oncological indications. We then searched for prospective studies aimed at confirming the promises of retrospective data.

RESULTS AND DISCUSSION

While evidence from nonclinical and retrospective clinical studies with these drugs appears highly promising, large scale prospective studies are either lacking or have failed to substantiate this promise. We provide a brief discussion of some of the challenges in repurposing. Principal challenges and obstacles relate to heterogeneity of cancers studied without considering their molecular signatures, trials with small sample size and short duration, failure consider issues of ethnicity of study population and effective antioncogenic doses of the drug studied.

WHAT IS NEW AND CONCLUSION

Well-designed prospective studies demonstrating efficacy are required for repurposing old drugs for oncology indications, just as they are for new chemical entities for any indication. Early and ongoing interactions with regulatory authorities are invaluable. We outline a tentative framework for a structured approach to repurposing old drugs for novel indications in oncology.

Mitochondria in cancer metabolism, an organelle whose time has come?

Mitochondria have long been controversial organelles in cancer. Early discoveries in cancer metabolism placed much emphasis on cytosolic contributions. Initial debate focused on if mitochondria had a role in cancer formation and progression at all. More recently the contributions of mitochondria to cancer development and progression have become firmly established. This has led to the identification of novel targets and inhibitors being studied as new therapeutic approaches. This review will summarize the role of mitochondria in cancer and highlight several agents under development.

Buformin suppresses proliferation and invasion via AMPK/S6 pathway in cervical cancer and synergizes with paclitaxel

Buformin is an old anti-diabetic agent and manifests potent anti-tumor activities in several malignancies. In the present study, we aimed to explore the functions of buformin in human cervical cancer. As our data shown, buformin exhibited significant anti-proliferative effects in a dose-dependent manner in 4 cervical cancer cell lines. Compared to the control, buformin notably suppressed colony formation and increased ROS production in C33A, Hcc94 and SiHa cells. Flow cytometric analysis showed that buformin induced marked cell cycle arrest but only resulted in mild apoptosis. The invasion of C33A and SiHa cells sharply declined with buformin treatment. Consistently, western blotting showed that buformin activated AMPK and suppressed S6, cyclin D1, CDK4, and MMP9. Moreover, we found that buformin enhanced glucose uptake and LDH activity, increased lactate level, while decreased ATP production in cervical cancer cells. In addition, low doses of buformin synergized with routine chemotherapeutic drugs (such as paclitaxel, cisplatin, and 5-FU) to achieve more significant anti-tumor effects. In vivo, a single use of buformin exerted moderate anti-tumor effects, and the combination with buformin and paclitaxel exhibited even greater suppressive effects. Buformin also consistently showed synergistic effects with paclitaxel in treating primary cultures of cervical cancer cells. Take together, we are the first to demonstrate that buformin suppresses cellular proliferation and invasion through the AMPK/S6 signaling pathway, which arrests cell cycle and inhibits cellular invasion. Buformin also could synergize with routine chemotherapies, producing much more powerful anti-tumor effects. With these findings, we strongly support buformin as a potent choice for treating cervical cancer, especially in combination with routine chemotherapy.