Treatment of metastatic renal cell carcinoma

Constitutional genetic variants as predictors of antiangiogenic therapy outcome in renal cell carcinoma

The development of specific angiogenesis inhibitors has drastically improved renal cancer treatment in recent years. Currently, four VEGF receptor inhibitors (sorafenib, sunitinib, pazopanib and axitinib), one anti-VEGF monoclonal antibody (bevacizumab) and two inhibitors of the mTOR pathway (temsirolimus and everolimus) have been approved to treat renal cell carcinoma (RCC), and several other molecules are under investigation. However, lack of response to antiangiogenic drugs and adverse drug reactions leading to treatment suspension are critical clinical problems that need to be solved. Because antiangiogenic drugs act on nonmalignant endothelial cells, the genetic background of the patient may play a crucial role determining the efficacy of these drugs. This article focuses on the identification of polymorphisms associated with antiangiogenic drugs outcome in RCC patients. It reviews and summarizes our current knowledge on this area and discusses future strategies to identify new biomarkers that could be used to personalize RCC management.

Prolyl hydroxylase 2 dependent and Von-Hippel-Lindau independent degradation of Hypoxia-inducible factor 1 and 2 alpha by selenium in clear cell renal cell carcinoma leads to tumor growth inhibition

Background

Clear cell renal cell carcinoma (ccRCC) accounts for more than 80% of the cases of renal cell carcinoma. In ccRCC deactivation of Von-Hippel-Lindau (VHL) gene contributes to the constitutive expression of hypoxia inducible factors 1 and 2 alpha (HIF-α), transcriptional regulators of several genes involved in tumor angiogenesis, glycolysis and drug resistance. We have demonstrated inhibition of HIF-1α by Se-Methylselenocysteine (MSC) via stabilization of prolyl hydroxylases 2 and 3 (PHDs) and a significant therapeutic synergy when combined with chemotherapy. This study was initiated to investigate the expression of PHDs, HIF-α, and VEGF-A in selected solid cancers, the mechanism of HIF-α inhibition by MSC, and to document antitumor activity of MSC against human ccRCC xenografts.

Methods

Tissue microarrays of primary human cancer specimens (ccRCC, head & neck and colon) were utilized to determine the incidence of PHD2/3, HIF-α, and VEGF-A by immunohistochemical methods. To investigate the mechanism(s) of HIF-α inhibition by MSC, VHL mutated ccRCC cells RC2 (HIF-1α positive), 786–0 (HIF-2α positive) and VHL wild type head & neck cancer cells FaDu (HIF-1α) were utilized. PHD2 and VHL gene specific siRNA knockdown and inhibitors of PHD2 and proteasome were used to determine their role in the degradation of HIF-1α by MSC.

Results

We have demonstrated that ccRCC cells express low incidence of PHD2 (32%), undetectable PHD3, high incidence of HIF-α (92%), and low incidence of VEGF-A compared to head & neck and colon cancers. This laboratory was the first to identify MSC as a highly effective inhibitor of constitutively expressed HIF-α in ccRCC tumors. MSC did not inhibit HIF-1α protein synthesis, but facilitated its degradation. The use of gene knockdown and specific inhibitors confirmed that the inhibition of HIF-1α was PHD2 and proteasome dependent and VHL independent. The effects of MSC treatment on HIF-α were associated with significant antitumor activity against ccRCC xenograft.

Conclusions

Our results show the role of PHD2/3 in stable expression of HIF-α in human ccRCC. Furthermore, HIF-1α degradation by MSC is achieved through PHD2 dependent and VHL independent pathway which is unique for HIF-α regulation. These data provide the basis for combining MSC with currently used agents for ccRCC.

Asymptomatic renal cell carcinoma with metastasis to the skin and duodenum: a case report and review of the literature

Renal cell carcinoma is known to have blood-borne metastasis. This is usually to the bone, lungs and brain. Other unusual metastatic presentations such as skin and bowel metastasis have also been described. In most cases, the metastasis occurs as a late manifestation in a patient with known primary renal cell carcinoma. A rare synchronous presentation of skin and duodenal metastasis in an otherwise asymptomatic patient is reported here. This patient presented with a skin lesion that, on excision, brought up the diagnosis of metastatic renal cell carcinoma. While the patient was waiting for surgery, she also developed melena that, on gastroscopy, confirmed a duodenal metastasis. This case highlights the importance of early recognition of otherwise unrelated lesions as presentations for an advanced renal malignancy.

PGE2 promotes renal carcinoma cell invasion through activated RalA

Incidence of kidney cancer is on the rise, and a better understanding of molecular mechanisms involved in the cancer invasion and metastasis is required for the development of curative therapeutics. In this study, we report that the proinflammatory cytokine prostaglandin E2 (PGE2) induces the malignant SN12C, but not benign HK2 kidney cell invasion. The PGE2 increases SN12C cell invasion through a signal pathway that encompasses EP2 and EP4, Akt, small GTPase RalA and Ral·GTP inactivator RGC2. The results support the idea that targeted interference of EP2/EP4 signal to RalA·GTP may provide benefit to patients diagnosed with advanced kidney cancer.

Acute activation of β2-adrenergic receptor regulates focal adhesions through βArrestin2- and p115RhoGEF protein-mediated activation of RhoA

β(2)-Adrenergic receptors (β(2)ARs) regulate cellular functions through G protein-transduced and βArrestin-transduced signals. β(2)ARs have been shown to regulate cancer cell migration, but the underlying mechanisms are not well understood. Here, we report that β(2)AR regulates formation of focal adhesions, whose dynamic remodeling is critical for directed cell migration. β(2)ARs induce activation of RhoA, which is dependent on βArrestin2 but not G(s). βArrestin2 forms a complex with p115RhoGEF, a guanine nucleotide exchange factor for RhoA that is well known to be activated by G(12/13)-coupled receptors. Our results show that βArrestin2 forms a complex with p115RhoGEF in the cytosol in resting cells. Upon β(2)AR activation, both βArrestin2 and p115RhoGEF translocate to the plasma membrane, with concomitant activation of RhoA and formation of focal adhesions and stress fibers. Activation of RhoA and focal adhesion remodeling may explain, at least in part, the role of β(2)ARs in cell migration. These results suggest that βArrestin2 may serve as a convergence point for non-G(12/13) and non-G(q) protein-coupled receptors to activate RhoA.

Current status of targeted therapy for advanced renal cell carcinoma

The treatment of metastatic renal cell carcinoma (mRCC) has recently evolved from being predominantly cytokine-based treatment to the use of targeted agents, which include sorafenib, sunitinib, bevacizumab (plus interferon alpha [IFN-α]), temsirolimus, everolimus, pazopanib, and most recently, axitinib. Improved understanding of the molecular pathways implicated in the pathogenesis of RCC has led to the development of specific targeted therapies for treating the disease. In Korea, it has been 5 years since targeted therapy became available for mRCC. Thus, we now have broader and better therapeutic options at hand, leading to a significantly improved prognosis for patients with mRCC. However, the treatment of mRCC remains a challenge and a major health problem. Many questions remain on the efficacy of combination treatments and on the best methods for achieving complete remission. Additional studies are needed to optimize the use of these agents by identifying those patients who would most benefit and by elucidating the best means of delivering these agents, either in combination or as sequential single agents. Furthermore, numerous ongoing research activities aim at improving the benefits of the new compounds in the metastatic situation or their application in the early phase of the disease. This review introduces what is currently known regarding the fundamental biology that underlies clear cell RCC, summarizes the clinical evidence supporting the benefits of targeted agents in mRCC treatment, discusses survival endpoints used in pivotal clinical trials, and outlines future research directions.

A phase I dose-escalation study of regorafenib (BAY 73-4506), an inhibitor of oncogenic, angiogenic, and stromal kinases, in patients with advanced solid tumors

PURPOSE

Regorafenib is a novel oral multikinase inhibitor of angiogenic (VEGFR1-3, TIE2), stromal (PDGFR-β, FGFR), and oncogenic kinases (KIT, RET, and RAF). This first-in-man, phase I dose-escalation study assessed the safety, pharmacokinetic, pharmacodynamic, and efficacy profiles of regorafenib in patients with advanced solid tumors.

PATIENTS AND METHODS

Patients aged 18 years or older with advanced solid tumors refractory to standard treatment were recruited. Regorafenib was administered orally for 21 days on/seven days off in repeating cycles, until discontinuation due to toxicity or tumor progression. Adverse events (AE) were assessed using National Cancer Institute Common Terminology Criteria for Adverse Events v3.0. Pharmacokinetic profiles were measured after a single dose and on day 21. Pharmacodynamic and efficacy evaluations included tumor perfusion assessment using dynamic contrast-enhanced MRI, plasma cytokines, and tumor response using RECIST (v1.0).

RESULTS

Fifty-three patients were enrolled into eight cohorts at dose levels from 10 to 220 mg daily. The recommended dose for future studies was determined to be 160 mg daily, with a treatment schedule of 21 days on/seven days off in repeating 28-day cycles. The most common drug-related grade 3 or 4 AEs were dermatologic AEs (hand-foot skin reaction, rash), hypertension, and diarrhea. Pharmacokinetic analysis revealed a similar exposure at steady state for the parent compound and two pharmacologically active metabolites. Tumor perfusion and plasma cytokine analysis showed biologic activity of regorafenib. Three of 47 evaluable patients achieved a partial response (renal cell carcinoma, colorectal carcinoma, and osteosarcoma).

CONCLUSION

Regorafenib showed an acceptable safety profile and preliminary evidence of antitumor activity in patients with solid tumors.

Economic evaluation of first-line treatments for metastatic renal cell carcinoma: a cost-effectiveness analysis in a health resource-limited setting

Background

To estimate, from the perspective of the Chinese healthcare system, the economic outcomes of five different first-line strategies among patients with metastatic renal cell carcinoma (mRCC).

Methods and Findings

A decision-analytic model was developed to simulate the lifetime disease course associated with renal cell carcinoma. The health and economic outcomes of five first-line strategies (interferon-alfa, interleukin-2, interleukin-2 plus interferon-alfa, sunitinib and bevacizumab plus interferon-alfa) were estimated and assessed by indirect comparison. The clinical and utility data were taken from published studies. The cost data were estimated from local charge data and current Chinese practices. Sensitivity analyses were used to explore the impact of uncertainty regarding the results. The impact of the sunitinib patient assistant program (SPAP) was evaluated via scenario analysis. The base-case analysis showed that the sunitinib strategy yielded the maximum health benefits: 2.71 life years and 1.40 quality-adjusted life-years (QALY). The marginal cost-effectiveness (cost per additional QALY) gained via the sunitinib strategy compared with the conventional strategy was $220,384 (without SPAP, interleukin-2 plus interferon-alfa and bevacizumab plus interferon-alfa were dominated) and $16,993 (with SPAP, interferon-alfa, interleukin-2 plus interferon-alfa and bevacizumab plus interferon-alfa were dominated). In general, the results were sensitive to the hazard ratio of progression-free survival. The probabilistic sensitivity analysis demonstrated that the sunitinib strategy with SPAP was the most cost-effective approach when the willingness-to-pay threshold was over $16,000.

Conclusions

Our analysis suggests that traditional cytokine therapy is the cost-effective option in the Chinese healthcare setting. In some relatively developed regions, sunitinib with SPAP may be a favorable cost-effective alternative for mRCC.

Baseline quality of life as a prognostic survival tool in patients receiving sunitinib for metastatic renal cell carcinoma

Background:

In a randomized phase III trial of sunitinib vs interferon-alfa (IFN-α) in metastatic renal cell carcinoma (mRCC), better baseline quality of life (QoL) was predictive of longer survival. Using this dataset, we have developed a novel prognostic tool that establishes a relationship between baseline QoL scores and median survival time.

Methods:

Baseline QoL was assessed using the FACT-Kidney Symptom Index-15 item (FKSI-15), its disease-related symptoms (FKSI-DRS) subscale, and the Functional Assessment of Cancer Therapy–General (FACT-G) scale. Weibull models estimated median progression-free survival (mPFS) and overall survival (mOS) as a function of baseline QoL.

Results:

Longer PFS and OS were associated with higher baseline FKSI-15, FKSI-DRS, and FACT-G scores (P<0.05), and baseline FKSI-15 score was the best predictor of survival. For example, for a baseline FKSI-15 score of 60, the predicted mPFS was 67.9 weeks, and predicted mOS was 240.6 weeks. The magnitude of benefit was greater with sunitinib vs IFN-α for a given baseline QoL score.

Conclusion:

This novel tool indicates that baseline FKSI-15 scores were linked to mPFS and mOS in a clear and interpretable way. The results support evaluation of patient-reported QoL symptoms at baseline as a prognostic indicator of survival in clinical research and practice.

A phase I study of temozolomide and everolimus (RAD001) in patients with newly diagnosed and progressive glioblastoma either receiving or not receiving enzyme-inducing anticonvulsants: an NCIC CTG study

PURPOSE

This phase I trial was designed to determine the recommended phase II dose(s) of everolimus (RAD001) with temozolomide (TMZ) in patients with glioblastoma (GBM). Patients receiving enzyme-inducing antiepileptic drugs (EIAEDs) and those not receiving EIAEDs (NEIAEDs) were studied separately.

PATIENTS AND METHODS

Enrollment was restricted to patients with proven GBM, either newly diagnosed or at first progression. Temozolomide was administered at a starting dose of 150 mg/m(2)/day for 5 days every 28 days, and everolimus was administered continuously at a starting dose of 2.5 mg orally on a daily schedule starting on day 2 of cycle 1 in 28-day cycles.

RESULTS

Thirteen patients receiving EIAEDs and 19 not receiving EIAEDs were enrolled and received 83 and 116 cycles respectively. Everolimus 10 mg daily plus TMZ 150 mg/m(2)/day for 5 days was declared the recommended phase II dose for the NEIAEDs cohort. In the EIAEDs group, doses were well tolerated without DLTs, and pharmacokinetic parameters indicated decreased everolimus exposure. Temozolomide pharmacokinetic parameters were unaffected by EIAEDs or everolimus. In the subset of 28 patients with measurable disease, 3 had partial responses (all NEIAEDs) and 16 had stable disease.

CONCLUSION

A dosage of 10 mg everolimus daily with TMZ 150 mg/m(2)/day for five consecutive days every 28 days in patients is the recommended dose for this regimen. Everolimus clearance is increased by EIAEDs, and patients receiving EIAEDs should be switched to NEIAEDs before starting this regimen.

Cytoreductive nephrectomy in the elderly: a population-based cohort from the USA

Study Type - Therapy (cohort) Level of Evidence 2b What's known on the subject? and What does the study add? While cytoreductive nephrectomy is associated with a survival benefit in the context of metastatic renal cell carcinoma, the rates of morbidity and perioperative mortality remain non-negligible. For example, perioperative mortality may be as high as 21% in elderly patients. The study shows that perioperative death amongst the elderly was substantially lower than what was previously reported from a single institutional report. Nonetheless, postoperative adverse outcomes were non-negligible in elderly patients relative to their younger counterparts. In consequence, these rates should be discussed at informed consent and a rigorous patient selection remains essential.

OBJECTIVE

• To examine the rate of perioperative mortality (PM), and other adverse outcomes in 'elderly' patients treated with cytoreductive nephrectomy (CNT).

MATERIAL AND METHODS

• Patients who underwent CNT for metastatic renal cell carcinoma were abstracted from the Nationwide Inpatient Sample (1998-2007). 'Elderly' was defined as ≥ 75 years, according to previous definition. • Endpoints consisted of PM, intraoperative and postoperative complications, blood transfusions and length of stay. • We adjusted for the effect of elderly status within five separate logistic regression models. Covariates consisted of comorbidity, race, gender, year of surgery and hospital region.

RESULTS

• Overall, CNT was performed in 504 (15.3%) elderly patients and in 2796 (84.7%) 'younger' patients (<75 years). • The rate of PM was 4.8% in elderly patients vs 1.9% in the younger patients (P < 0.001). Similarly, the rates of blood transfusions (29.8 vs 21.5%), postoperative complications (27.8 vs 22.8%), and prolonged length of stay (≥ 8 days) were higher in the elderly (45.0 vs 32.0%; all P < 0.001). • In multivariable analyses, elderly patients were 2.2-, 1.5-, and 1.6 fold more likely to experience PM, to receive a blood transfusion and to be hospitalized ≥ 8 days than the younger patients.

CONCLUSIONS

• Although the rate of PM was substantially lower than 21%, elderly patients are significantly more likely to die after this type of surgery, to receive a transfusion, and to experience a prolonged length of stay. • These facts and figures should be discussed at informed consent and a rigorous patient selection is essential.

Prognostic significance of CD45RO+ memory T cells in renal cell carcinoma

Background:

Memory T cells are well known to have a critical role for host defense in humans. However, their role in actual human cancer remains largely unknown. In this study, we tried to reveal the clinical importance of tumour-infiltrating CD45RO+ memory T cells in renal cell carcinoma (RCC).

Methods:

We analysed 105 patients with RCC, who received radical or partial nephrectomy. Those were 65 in TNM stage I, 7 in stage II, 15 in stage III, and 18 in stage IV, respectively. CD45RO expression was evaluated by immunohistochemistry. CD4 and CD8 expressions were also systematically assessed in the same manner.

Results:

Patients with higher TNM stage or high nuclear grade were found to have higher densities of CD45RO. Furthermore, CD45RO status was positively correlated with preoperative C-reactive protein level. In prognostic analysis, CD45RO+lo patients had a significantly better prognosis than CD45RO+hi patients. There was also a significant difference between CD4+lo and CD4+hi groups, whereas no significant difference was observed in CD8 T-cell status. Finally, multivariate analysis revealed that CD45RO+ status was the independent prognostic factor for patient overall survival.

Conclusion:

CD45RO+ memory T-cell status has a significant independent prognostic value, indicating that the adaptive immune response is functionally critical in human RCC.

Targeting the tumor microenvironment: focus on angiogenesis

Tumorigenesis is a complex multistep process involving not only genetic and epigenetic changes in the tumor cell but also selective supportive conditions of the deregulated tumor microenvironment. One key compartment of the microenvironment is the vascular niche. The role of angiogenesis in solid tumors but also in hematologic malignancies is now well established. Research on angiogenesis in general, and vascular endothelial growth factor in particular, is a major focus in biomedicine and has led to the clinical approval of several antiangiogenic agents including thalidomide, bevacizumab, sorafenib, sunitinib, pazopanib, temesirolimus, and everolimus. Indeed, antiangiogenic agents have significantly changed treatment strategies in solid tumors (colorectal cancer, renal cell carcinoma, and breast cancer) and multiple myeloma. Here we illustrate important aspects in the interrelationship between tumor cells and the microenvironment leading to tumor progression, with focus on angiogenesis, and summarize derived targeted therapies.

Transcriptional control mechanisms associated with the nucleotide receptor P2X7, a critical regulator of immunologic, osteogenic, and neurologic functions

The nucleotide receptor P2X(7) is an attractive therapeutic target and potential biomarker for multiple inflammatory and neurologic disorders, and it is expressed in several immune, osteogenic, and neurologic cell types. Aside from its role in the nervous system, it is activated by ATP released at sites of tissue damage, inflammation, and infection. Ligand binding to P2X(7) stimulates many cell responses, including calcium fluxes, MAPK activation, inflammatory mediator release, and apoptosis. Much work has centered on P2X(7) action in cell death and mediator processing (e.g., pro-interleukin-1 cleavage by the inflammasome), but the contribution of P2X(7) to transcriptional regulation is less well defined. This review will focus on the growing evidence for the importance of nucleotide-mediated gene expression, highlight several animal models, human genetic, and clinical studies that support P2X(7) as a therapeutic target, and discuss the latest developments in anti-P2X(7) clinical trials.

Methylselenocysteine: a promising antiangiogenic agent for overcoming drug delivery barriers in solid malignancies for therapeutic synergy with anticancer drugs

INTRODUCTION

Despite progress, chemotherapeutic response in solid malignancies has remained limited. Although initial results of the use of antiangiogenic agents in combination chemotherapy indicated an enhanced therapeutic response, recent data indicate that the surviving cancer is not only able to surmount therapy, but also actually able to adapt a more aggressive metastatic phenotype. Thus, selecting an antiangiogenic agent that is less likely to lead to tumor resurgence is a key to future therapeutic success of antiangiogenic agents in a combinatorial setting.

AREAS COVERED

Against the broad spectrum of antiangiogenic agents used at present in the clinic, the putative benefits of the use of organoselenium compounds, such as methylselenocysteine (MSC), are discussed in this review.

EXPERT OPINION

MSC, being part of the mammalian physiology, is a well-tolerated, versatile and economical antiangiogenic agent. It downregulates multiple key upstream tumor survival markers, and enhances tumor drug delivery, at a given systemic dose of an anticancer agent, while protecting normal tissue from cytotoxic adverse effects. Further clinical trials, especially in poorly differentiated cancers, are warranted.

Renal cell carcinoma in children and adolescents

Although rare in children and adolescents, renal cell carcinomas (RCCs) raise important questions concerning the best treatment approach and accurate pathologic classification. The differences emerging between childhood and adulthood RCC probably prevent any direct generalized application of therapies to children that are validated for adults. The translocation type of RCC, which forms a distinct category characterized by translocations involving Xp11.2 or, less frequently, 6p21, has recently emerged as the predominant type of RCC in children and adolescents, whereas it is rarely diagnosed in adults. This new finding emphasizes how important it is to prospectively classify RCCs in children with standardized 'modern' diagnoses. The standard cornerstone of therapy for RCC in children and adolescents remains radical nephrectomy. Nephron-sparing surgery is currently recommended in adults for selected small-volume tumors, but additional data are needed before this experience can be extensively transferred to the pediatric population. The therapeutic value of complete retroperitoneal lymph node dissection is still controversial, especially in patients without suspected nodal involvement, be they adults or children. The backbone of systemic therapies for adult RCC has recently been changed by the introduction of drugs designed to target tumor-related angiogenesis and signal transduction. It is worth noting that the largest clinical efficacy trials on targeted molecules have been conducted on clear-cell RCC. While targeted drugs have become the standard of care for adult metastatic RCC, there are currently no published reports on their role in children, and their use should be considered for patients with unresectable metastatic or advanced-stage RCC. On the other hand, the utility of targeted therapies in the adjuvant setting remains to be seen for both adults and children.

Prediction of progression-free survival rates after bevacizumab plus interferon versus interferon alone in patients with metastatic renal cell carcinoma: comparison of a nomogram to the Motzer criteria

BACKGROUND

The combination of bevacizumab plus interferon (BEV+IFN) for treatment of metastatic renal cell carcinoma (mRCC) is associated with improved progression-free survival (PFS) in a phase 3 study.

OBJECTIVE

To develop a novel model for prediction of individual PFS using data from the randomized, controlled phase 3 trial of BEV + IFN or interferon alone. The ability of the Motzer criteria for prediction of PFS was also assessed.

DESIGN, SETTING, AND PARTICIPANTS

Pretreatment parameters of 628 patients were included in the Cox regression model predicting PFS at 6, 12, 18, and 24 mo. BEV+IFN was administered to 337 patients; 291 patients received interferon alone. The developed model and the Motzer criteria were internally validated using Harrell's concordance index and calibrated.

RESULTS AND LIMITATIONS

Median PFS was 10.2 versus 4.6 mo (p < 0.001) for patients receiving BEV + IFN or interferon alone, respectively. The novel model relying on age, Karnofsky performance status, baseline albumin, alkaline phosphatase, and time from primary diagnosis to treatment resulted in the highest discrimination (area under the curve [AUC]: 72.8, 75.0, 72.8, and 70.8% at 6, 12, 18, and 24 mo). The AUC of the Motzer criteria risk groups was 63.7, 61.8, 58.6, and 51.8% for the same time points. Comparison of discriminatory ability between the developed model and the Motzer criteria showed statistically significant differences (all p ≤ 0.02). An external validation of the new model is warranted.

CONCLUSIONS

The developed model identified prognostic factors of PFS in mRCC patients treated with BEV+IFN or interferon alone and quantified individual risk of PFS. Relative to the Motzer criteria, the novel model demonstrated better discriminatory properties. The model may serve clinicians in identifying patients who can benefit the most from BEV+IFN versus interferon alone.

Enhancing mda-7/IL-24 therapy in renal carcinoma cells by inhibiting multiple protective signaling pathways using sorafenib and by Ad.5/3 gene delivery

We have determined whether an adenovirus that comprises the tail and shaft domains of a serotype 5 virus and the knob domain of a serotype 3 virus expressing MDA-7/IL-24, Ad.5/3-mda-7, more effectively infects and kills renal carcinoma cells (RCCs) compared to a serotype 5 virus, Ad.5-mda-7. RCCs are a tumor cell type that generally does not express the receptor for the type 5 adenovirus; the coxsackie and adenovirus receptor (CAR). Ad.5/3-mda-7 infected RCCs to a much greater degree than Ad.5-mda-7. MDA-7/IL-24 protein secreted from Ad.5/3-mda-7-infected RCCs induced MDA-7/IL-24 expression and promoted apoptosis in uninfected "bystander" RCCs. MDA-7/IL-24 killed both infected and bystander RCCs via CD95 activation. Knockdown of intracellular MDA-7/IL-24 in uninfected RCCs blocked the lethal effects of conditioned media. Infection of RCC tumors in one flank, with Ad.5/3-mda-7, suppressed growth of infected tumors and reduced the growth rate of uninfected tumors implanted on the opposite flank. The toxicity of the serotype 5/3 recombinant adenovirus to express MDA-7/IL-24 was enhanced by combined molecular or small molecule inhibition of MEK1/2 and PI3K; inhibition of mTOR, PI3K and MEK1/2; or use of the multi-kinase inhibitor sorafenib. In RCCs, combined inhibition of cytoprotective cell signaling pathways enhanced the MDA-7/IL-24-induction of CD95 activation, with greater mitochondrial dysfunction due to loss of MCL-1 and BCL-XL expression, and tumor cell death. Treatment of RCC tumors in vivo with sorafenib also enhanced Ad.5/3-mda-7 toxicity and prolonged animal survival. Future combinations of these approaches hold promise for developing a more effective therapy for kidney cancer.