ALK Inhibition With Alectinib for Refractory Metastatic Renal Cell Carcinoma With ALK Rearrangement: A Rare Case Report and Literature Review.

ALK-rearranged RCC refractory to several lines of treatment has a durable response when treated with alectinib.

Checkpoint Inhibitor Induced Acute Liver Failure.

Immune checkpoint inhibitors have become essential antineoplastic agents in medical oncology over the past decade. However, they are associated with potentially fatal multisystem abnormalities, with increasing concern in gastrointestinal tract and its associated organs. We present a patient with advanced renal cell carcinoma, who presented with acute liver failure after the first dose of combined immunotherapy with nivolumab and ipilimumab. A thorough evaluation for viral, metabolic, and autoimmune causes was unremarkable. He was managed with steroids and made significant improvement. To our knowledge, this is the first documented case of acute liver failure following ipilimumab and nivolumab.

Safety of nivolumab monotherapy in five cancer types: pooled analysis of post-marketing surveillance in Japan.

BACKGROUND: Nivolumab has been approved for treating ≥ 10 cancer types. However, there is limited information on the incidence of rare, but potentially serious, treatment-related adverse events (TRAEs), as well as notable TRAEs in patients with certain medical disorders or older patients in Japan. METHODS: We performed pooled analyses of data from published post-marketing surveillance in Japan of nivolumab monotherapy for patients with malignant melanoma, non-small cell lung cancer, renal cell carcinoma, head and neck cancer, and gastric cancer to determine the frequencies of 20 categories of TRAEs of special interest overall and in patient groups with higher perceived safety risks (history of autoimmune disease, interstitial lung disease, tuberculosis, or hepatitis B/C; patients vaccinated during nivolumab treatment; and older patients [≥ 75 years]). RESULTS: The overall population comprised 7421 patients treated with nivolumab. TRAEs were reported in 49.1% of patients, with grade ≥ 3 TRAEs in 16.7%. Endocrine disorders (14.4%), hepatobiliary disorders (10.9%), and interstitial lung disease (7.0%) were the three most common categories (any grade). The incidences of rare TRAEs with high risk of becoming serious, which occurred in < 1% of patients, were consistent with those in previous reports. The frequencies of TRAEs were not markedly increased in the specified patient groups relative to the overall population. CONCLUSION: To our knowledge, this is the largest study examining the safety of nivolumab-treated patients in real-world clinical practice including rare but potentially serious TRAEs. We found no new signals in the safety of nivolumab among the patient groups relative to the overall population, and no additional safety measures are required in these groups. Trial registration UMIN000048892 (overall analysis), JapicCTI-163272 (melanoma), Japic-163271 (non-small cell lung cancer), JapicCTI-184071 (head and neck cancer), JapicCTI-184070 (gastric cancer), and JapicCTI-184069 (renal cell cancer).

Neoadjuvant toripalimab combined with axitinib in patients with locally advanced clear cell renal cell carcinoma: a single-arm, phase II trial.

BACKGROUND: A combination of axitinib and immune checkpoint inhibitors (ICIs) demonstrated promising efficacy in the treatment of advanced renal cell carcinoma (RCC). This study aims to prospectively evaluate the safety, efficacy, and biomarkers of neoadjuvant toripalimab plus axitinib in non-metastatic clear cell RCC. METHODS: This is a single-institution, single-arm phase II clinical trial. Patients with non-metastatic biopsy-proven clear cell RCC (T2-T3N0-1M0) are enrolled. Patients will receive axitinib 5 mg twice daily combined with toripalimab 240 mg every 3 weeks (three cycles) for up to 12 weeks. Patients then will receive partial (PN) or radical nephrectomy (RN) after neoadjuvant therapy. The primary endpoint is objective response rate (ORR). Secondary endpoints include disease-free survival, safety, and perioperative complication rate. Predictive biomarkers are involved in exploratory analysis. RESULTS: A total of 20 patients were enrolled in the study, with 19 of them undergoing surgery. One patient declined surgery. The primary endpoint ORR was 45%. The posterior distribution of πORR had a mean of 0.44 (95% credible intervals: 0.24-0.64), meeting the predefined primary endpoint with an ORR of 32%. Tumor shrinkage was observed in 95% of patients prior to nephrectomy. Furthermore, four patients achieved a pathological complete response. Grade ≥3 adverse events occurred in 25% of patients, including hypertension, hyperglycemia, glutamic pyruvic transaminase/glutamic oxaloacetic transaminase (ALT/AST) increase, and proteinuria. Postoperatively, one grade 4a and eight grade 1-2 complications were noted. In comparison to patients with stable disease, responders exhibited significant differences in immune factors such as Arginase 1(ARG1), Melanoma antigen (MAGEs), Dendritic Cell (DC), TNF Superfamily Member 13 (TNFSF13), Apelin Receptor (APLNR), and C-C Motif Chemokine Ligand 3 Like 1 (CCL3-L1). The limitation of this trial was the small sample size. CONCLUSION: Neoadjuvant toripalimab combined with axitinib shows encouraging activity and acceptable toxicity in locally advanced clear cell RCC and warrants further study. TRIAL REGISTRATION NUMBER: clinicaltrials.gov, NCT04118855.

Unconventional mechanism of action and resistance to rapalogs in renal cancer.

mTORC1 is aberrantly activated in renal cell carcinoma (RCC) and is targeted by rapalogs. As for other targeted therapies, rapalogs clinical utility is limited by the development of resistance. Resistance often results from target mutation, but mTOR mutations are rarely found in RCC. As in humans, prolonged rapalog treatment of RCC tumorgrafts (TGs) led to resistance. Unexpectedly, explants from resistant tumors became sensitive both in culture and in subsequent transplants in mice. Notably, resistance developed despite persistent mTORC1 inhibition in tumor cells. In contrast, mTORC1 became reactivated in the tumor microenvironment (TME). To test the role of the TME, we engineered immunocompromised recipient mice with a resistance mTOR mutation (S2035T). Interestingly, TGs became resistant to rapalogs in mTORS2035T mice. Resistance occurred despite mTORC1 inhibition in tumor cells and could be induced by coculturing tumor cells with mutant fibroblasts. Thus, enforced mTORC1 activation in the TME is sufficient to confer resistance to rapalogs. These studies highlight the importance of mTORC1 inhibition in nontumor cells for rapalog antitumor activity and provide an explanation for the lack of mTOR resistance mutations in RCC patients.

Sex and survival outcomes in patients with renal cell carcinoma receiving first-line immune-based combinations.

BACKGROUND: There is an ongoing debate as to whether sex could be associated with immune checkpoint inhibitor (ICI) benefit. Existing literature data reveal contradictory results, and data on first-line immune combinations are lacking. METHOD: This was a real-world, multicenter, international, observational study to determine the sex effects on the clinical outcomes in metastatic renal cell carcinoma (mRCC) patients treated with immuno-oncology combinations as first-line therapy. RESULTS: A total of 1827 mRCC patients from 71 cancer centers in 21 countries were included. The median OS was 38.7 months (95% CI 32.7-44.2) in the overall study population: 40.0 months (95% CI 32.7-51.6) in males and 38.7 months (95% CI 26.4-41.0) in females (p = 0.202). The median OS was higher in males vs. females in patients aged 18-49y (36.9 months, 95% CI 29.0-51.6, vs. 24.8 months, 95% CI 16.8-40.4, p = 0.426, with + 19% of 2y-OS rate, 72% vs. 53%, p = 0.006), in the clear cell histology subgroup (44.2 months, 95% CI 35.8-55.7, vs. 38.7 months, 95% CI 26.0-41.0, p = 0.047), and in patients with sarcomatoid differentiation (34.4 months, 95% CI 26.4-59.0, vs. 15.3 months, 95% CI 8.9-41.0, p < 0.001). Sex female was an independent negative prognostic factor in the sarcomatoid population (HR 1.72, 95% CI 1.15 - 2.57, p = 0.008). CONCLUSIONS: Although the female's innate and adaptive immunity has been observed to be more active than the male's, women in the subgroup of clear cell histology, sarcomatoid differentiation, and those under 50 years of age showed shorter OS than males.

The role of cyclin-dependent kinase inhibitor 3 in the proliferation and migration of renal cell carcinoma.

The cyclin-dependent kinase inhibitor 3 (CDKN3) gene, is over expressed in renal cell carcinoma (RCC). However, the cell biology functions of RCC are not well understood. The present study aimed to verify the ability of CDKN3 to promote the proliferation and migration of RCC through in vitro experiments. Subsequently, the clinical prognostic effects were analyzed using The Cancer Genome Atlas (TCGA; https://www.cancer.gov/) and Gene Expression Omnibus (GEO; https://www.ncbi.nlm.nih.gov/geo/). The chelators, di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT), an analogue of the anti-tumor agent, were screened through bioinformatics analysis. The expression of CDKN3 is positively correlated with the IC50 of Dp44mT. In two RCC cell lines, 786-0 and Caki-1, we conducted small interfering RNA (siRNA) knockdown of CDKN3 and overexpression of CDKN3 by transfection plasmid. Subsequently, we administered Dp44mT to examine the resulting alterations in cell proliferation, migration, and apoptosis, thereby elucidating the role of CDKN3 and Dp44mT in these processes. The results of the experiment revealed a positive association between CDKN3 expression and the proliferation of RCC cell lines. Down-regulating CDKN3 significantly increased the apoptosis rate and inhibited cell migration in 786-0 and Caki-1 cells. Furthermore, bioinformatics analysis revealed a high expression of CDKN3 in RCC and a negative association between CDKN3 expression and survival. Gene set enrichment analysis (GSEA) revealed a significant association between high CDKN3 expression and the cell cycle pathway. Furthermore, we identified Dp44mT as a drug highly correlated with CDKN3 through the database. Subsequent addition of Dp44mT resulted in similar findings to those observed upon CDKN3 knockdown. Our findings have important implications for the diagnosis and treatment of CDKN3 in RCC. Additionally, Dp44mT is likely to be a promising candidate for future clinical applications.

Format-tuning of in vivo-launched bispecific T cell engager enhances efficacy against renal cell carcinoma.

BACKGROUND: Advanced clear cell renal cell carcinoma (ccRCC) is a prevalent kidney cancer for which long-term survival rates are abysmal, though immunotherapies are showing potential. Not yet clinically vetted are bispecific T cell engagers (BTEs) that activate T cell-mediated cancer killing through intercellular synapsing. Multiple BTE formats exist, however, with limited cross-characterizations to help optimize new drug design. Here, we developed BTEs to treat ccRCC by targeting carbonic anhydrase 9 (CA9) while characterizing the persistent BTE (PBTE) format and comparing it to a new format, the persistent multivalent T cell engager (PMTE). These antibody therapies against ccRCC are developed as both recombinant and synthetic DNA (synDNA) medicines. METHODS: Antibody formatting effects on binding kinetics were assessed by flow cytometry and intercellular synaptic strength assays while potency was tested using T-cell activation and cytotoxicity assays. Mouse models were used to study antibody plasma and tumor pharmacokinetics, as well as antitumor efficacy as both recombinant and synDNA medicines. Specifically, three models using ccRCC cell line xenografts and human donor T cells in immunodeficient mice were used to support this study. RESULTS: Compared with a first-generation BTE, we show that the PBTE reduced avidity, intercellular synaptic strength, cytotoxic potency by as much as 33-fold, and ultimately efficacy against ccRCC tumors in vivo. However, compared with the PBTE, we demonstrate that the PMTE improved cell avidity, restored intercellular synapses, augmented cytotoxic potency by 40-fold, improved tumor distribution pharmacokinetics by 2-fold, and recovered synDNA efficacy in mouse tumor models by 20-fold. All the while, the PMTE displayed a desirable half-life of 4 days in mice compared with the conventional BTE's 2 hours. CONCLUSIONS: With impressive efficacy, the CA9-targeted PMTE is a promising new therapy for advanced ccRCC, which can be effectively delivered through synDNA. The highly potent PMTE format itself is a promising new tool for future applications in the multispecific antibody space.

First-Line Immune Combination Therapies for Nonclear Cell Versus Clear Cell Metastatic Renal Cell Carcinoma: Real-World Multicenter Data From Germany.

INTRODUCTION: The aim was to compare treatment outcomes of clear cell metastatic renal cell carcinoma (ccmRCC) versus non-ccmRCC (nccmRCC) patients who received first-line immune combination therapies. MATERIALS AND METHODS: Within our retrospective multi-institutional consecutive database of eight tertiary-care centers, we identified mRCC patients treated with first-line immune combination therapies between 11/2017 and 12/2022. Using log-rank analysis and multivariable Cox regression, we tested for differences in overall survival (OS) and progression-free survival (PFS) of nccmRCC versus ccmRCC patients. Covariables consisted of age at diagnosis, sex, International Metastatic Renal Cell Carcinoma Database Consortium risk groups, Eastern Cooperative Oncology Group status, and sarcomatoid feature. RESULTS: Of 289 study patients, 39 (13%) patients harbored nccmRCC. Median OS was 37 months versus not reached for ccmRCC versus nccmRCC patients (P = .6). Median PFS was 13 versus 15 months (P = .9). Multivariable Cox regression models did not identify nccmRCC as an independent predictor of higher overall mortality in mRCC patients (hazard ratio [HR]: 1.23; P = .6) or a higher progression rate (HR: 1.0; P = 1.0). CONCLUSION: In our real-world multi-institutional study, no differences in OS and PFS between ccmRCC and nccmRCC patients receiving first-line immune combination treatment were observed, even after adjustment for important patient and tumor characteristics. More prospective trials in nccmRCC patients are needed.

Racial and Ethnic Disparities in Survival Outcomes of Metastatic Renal Cell Carcinoma Patients Receiving Immunotherapy.

BACKGROUND: Immune checkpoint inhibitors (ICI) have significantly improved survival outcomes of metastatic renal cell carcinoma (mRCC). However, ethnic and racial minorities are often underrepresented in ICI clinical trials, leading to limited knowledge about ICI-specific survival outcomes for mRCC across different racial and ethnic groups. We investigated the impact of race and ethnicity on the ICI-specific survival outcomes of mRCC. MATERIALS: We used The National Cancer Database (NCDB) to retrieve the data of 4858 mRCC patients diagnosed from 2014 to 2019 and receiving ICI-based regimens. We then compared survival outcomes using the Kaplan-Meier method and the Log-rank test. We analyzed the data using univariate and multivariable Cox regression analysis, adjusted for age, sex, comorbidity index, treatment centers, and grade. RESULTS: White and Asian patients had significantly longer median overall survival (mOS) than African American (AA) patients (23.2 [95% CI 21.6, 24.7; P = .001] and 22.2 [95% CI 16.4, 55.1; P = .047] vs. 14.8 [95% CI 11.9, 19.2] months, respectively). After adjustment, White patients had significantly longer median OS (adjusted hazard ratio [HR] 0.71 [95% CI 0.58, 0.84]; P = .001). There was no significant difference in the mOS between Hispanic and non-Hispanic patients (P = .39). CONCLUSION: Black race is an independent predictor of ICI-related survival in mRCC patients, independent of sociodemographics, clinicopathological, and treatment-related factors. Future research is required to understand the underlying reasons for these disparities, including potential genetic or biological differences and social and environmental factors.

First-Line Treatments and Management of Metastatic Renal Cell Carcinoma Patients: An Italian Interdisciplinary Uro-Oncologic Group Algorithm.

The treatment landscape for metastatic renal cell carcinoma (mRCC) has undergone significant transformations in recent years. The introduction of novel combination therapies involving tyrosine kinase inhibitors (TKI) and immune checkpoint inhibitors has resulted in improved oncological outcomes compared to traditional TKI monotherapy. In this evolving paradigm, the pivotal role of the multidisciplinary tumor board is underscored, particularly in shaping the therapeutic trajectory for patients eligible for locoregional interventions like cytoreductive nephrectomy and metastasectomy. In cases where systemic treatment is deemed appropriate, the absence of direct comparisons among the various combination therapies complicates the selection of a first-line approach. The clinician is faced with the challenge of making decisions based on patient-specific factors such as performance status, risk classification according to the International Metastatic Renal Cell Carcinoma Database Consortium, comorbidities, and disease characteristics, including the number and location of metastases and tumor histology. Considering these concerns, we propose, as a member of a Tuscany Interdisciplinary Uro-Oncologic Group, an algorithm to streamline the decision-making process for mRCC patients, offering guidance to clinicians in their day-to-day clinical practice.

Cross-sectional study of therapy-related expectations/concerns of patients with metastatic renal cell carcinoma and physicians in Japan.

OBJECTIVE: To achieve patient-centricity in metastatic renal cell carcinoma (mRCC) treatment, it is essential to clarify the differences in perspectives between patients and physicians. This cross-sectional analysis of a web survey aimed to clarify the differences in expectations and concerns between mRCC patients and physicians regarding systemic mRCC therapy in Japan. METHODS: Surveys from 83 patients and 165 physicians were analyzed. RESULTS: The top three most significant differences in expectations of systemic therapy between patients and physicians (patient-based physician value) were "Chance of achieving treatment-free status" (-30.1%, p < 0.001), "Longer survival" (+25.8%, p < 0.001), and "Chance of eliminating all evidence of disease" (-25.6%, p < 0.001). The top three most significant differences in concerns for systemic therapy between patients and physicians (patient-based physician value) were "Lack of efficacy" (+36.1%, p < 0.001), "Lack of knowledge of treatment" (-28.2%, p < 0.001), and "Daily activities affected by side effects" (+22.3%, p < 0.001). Diarrhea, fatigue/malaise, and nausea/vomiting were patients' most distressing adverse events; 50.6% of patients had difficulty telling their physicians about adverse events such as fatigue, anxiety, and depression. CONCLUSIONS: This study demonstrated a gap between patients with mRCC and physicians in their expectations and concerns for systemic therapy. Japanese patients with mRCC suffer from a number of adverse events, some of which are not shared with physicians. This study highlights the importance of communicating well with patients in clinical practice to achieve patient-centricity in systemic treatment for mRCC.

Safety and efficacy outcomes of early cessation of anti-PD1 therapy in patients 80 years or older: A retrospective cohort study.

Older patients have similar immune checkpoint inhibitor efficacy and rates of adverse events as younger patients, but appear to have decreased tolerability, particularly in the oldest patient cohort (>80 years), often leading to early cessation of therapy. We aimed to determine whether early discontinuation impacts efficacy of anti-PD-1 therapy in patients ≥80 years old. In this retrospective, multicenter, international cohort study, we examined 773 patients with 4 tumor types who were at least 80 years old and treated with anti-PD-1 therapy. We determined response rate, overall survival (OS), and progression-free survival (PFS) in patients who discontinued therapy early (<12 months) for reasons other than progression or death. We used descriptive statistics for demographics, response, and toxicity rates. Survival statistics were described using Kaplan Meier curves. Median (range) age at anti-PD-1 initiation was 83.0 (75.8-97.0) years. The cancer types included were melanoma (n = 286), non-small cell lung cancer (NSCLC) (n = 345), urothelial cell carcinoma (UCC) (n = 108), and renal cell carcinoma (RCC) (n = 34). Of these, 102 met the primary endpoint of <12 months to discontinuation for reasons other than death or progression. Median PFS and OS, respectively, for these patients were 34.4 months and 46.6 months for melanoma, 15.8 months and 23.4 months for NSCLC, and 10.4 months and 15.8 months for UCC. This study suggests geriatric patients who have demonstrated therapeutic benefit and discontinued anti-PD-1 therapy at less than 12 months of duration for reasons other than progression may have durable clinical benefit without additional therapy.

Targeting mTOR and survivin concurrently potentiates radiation therapy in renal cell carcinoma by suppressing DNA damage repair and amplifying mitotic catastrophe.

BACKGROUND: Renal cell carcinoma (RCC) was historically considered to be less responsive to radiation therapy (RT) compared to other cancer indications. However, advancements in precision high-dose radiation delivery through single-fraction and multi-fraction stereotactic ablative radiotherapy (SABR) have led to better outcomes and reduced treatment-related toxicities, sparking renewed interest in using RT to treat RCC. Moreover, numerous studies have revealed that certain therapeutic agents including chemotherapies can increase the sensitivity of tumors to RT, leading to a growing interest in combining these treatments. Here, we developed a rational combination of two radiosensitizers in a tumor-targeted liposomal formulation for augmenting RT in RCC. The objective of this study is to assess the efficacy of a tumor-targeted liposomal formulation combining the mTOR inhibitor everolimus (E) with the survivin inhibitor YM155 (Y) in enhancing the sensitivity of RCC tumors to radiation. EXPERIMENTAL DESIGN: We slightly modified our previously published tumor-targeted liposomal formulation to develop a rational combination of E and Y in a single liposomal formulation (EY-L) and assessed its efficacy in RCC cell lines in vitro and in RCC tumors in vivo. We further investigated how well EY-L sensitizes RCC cell lines and tumors toward radiation and explored the underlying mechanism of radiosensitization. RESULTS: EY-L outperformed the corresponding single drug-loaded formulations E-L and Y-L in terms of containing primary tumor growth and improving survival in an immunocompetent syngeneic mouse model of RCC. EY-L also exhibited significantly higher sensitization of RCC cells towards radiation in vitro than E-L and Y-L. Additionally, EY-L sensitized RCC tumors towards radiation therapy in xenograft and murine RCC models. EY-L mediated induction of mitotic catastrophe via downregulation of multiple cell cycle checkpoints and DNA damage repair pathways could be responsible for the augmentation of radiation therapy. CONCLUSION: Taken together, our study demonstrated the efficacy of a strategic combination therapy in sensitizing RCC to radiation therapy via inhibition of DNA damage repair and a substantial increase in mitotic catastrophe. This combination therapy may find its use in the augmentation of radiation therapy during the treatment of RCC patients.

BIGH3 mediates apoptosis and gap junction failure in osteocytes during renal cell carcinoma bone metastasis progression.

Renal cell carcinoma (RCC) bone metastatis progression is driven by crosstalk between tumor cells and the bone microenvironment, which includes osteoblasts, osteoclasts, and osteocytes. RCC bone metastases (RCCBM) are predominantly osteolytic and resistant to antiresorptive therapy. The molecular mechanisms underlying pathologic osteolysis and disruption of bone homeostasis remain incompletely understood. We previously reported that BIGH3/TGFBI (transforming growth factor-beta-induced protein ig-h3, shortened to BIGH3 henceforth) secreted by colonizing RCC cells drives osteolysis by inhibiting osteoblast differentiation, impairing healing of osteolytic lesions, which is reversible with osteoanabolic agents. Here, we report that BIGH3 induces osteocyte apoptosis in both human RCCBM tissue specimens and in a preclinical mouse model. We also demonstrate that BIGH3 reduces Cx43 expression, blocking gap junction (GJ) function and osteocyte network communication. BIGH3-mediated GJ inhibition is blocked by the lysosomal inhibitor hydroxychloroquine (HCQ), but not osteoanabolic agents. Our results broaden the understanding of pathologic osteolysis in RCCBM and indicate that targeting the BIGH3 mechanism could be a combinational strategy for the treatment of RCCBM-induced bone disease that overcomes the limited efficacy of antiresorptives that target osteoclasts.

Therapeutic Drug Monitoring of Pazopanib in Renal Cell Carcinoma and Soft Tissue Sarcoma: A Systematic Review.

BACKGROUND: Pazopanib, an anti-angiogenic multitarget tyrosine kinase inhibitor, has been approved for the treatment of metastatic renal cell carcinoma and soft tissue sarcoma. However, its recommended dose does not always produce consistent outcomes, with some patients experiencing adverse effects or toxicity. This variability is due to differences in the systemic exposure to pazopanib. This review aimed to establish whether sufficient evidence exists for the routine or selective therapeutic drug monitoring of pazopanib in adult patients with approved indications. METHODS: A systematic search of the PubMed and Web of Science databases using search terms related to pazopanib and therapeutic drug monitoring yielded 186 and 275 articles, respectively. Ten articles associated with treatment outcomes or toxicity due to drug exposure were selected for review. RESULTS: The included studies were evaluated to determine the significance of the relationship between drug exposure/Ctrough and treatment outcomes and between drug exposure and toxicity. A relationship between exposure and treatment outcomes was observed in 5 studies, whereas the trend was nonsignificant in 4 studies. A relationship between exposure and toxicity was observed in 6 studies, whereas 2 studies did not find a significant relationship; significance was not reported in 3 studies. CONCLUSIONS: Sufficient evidence supports the therapeutic drug monitoring of pazopanib in adult patients to improve its efficacy and/or safety in the approved indications.

Molecular and functional characterization of reversible-sunitinib-tolerance state in human renal cell carcinoma.

Therapy failure with the tyrosine kinase inhibitor (TKI) sunitinib remains a great challenge in metastatic renal cell carcinoma (mRCC). Growing evidence indicates that the tumour subpopulation can enter a transient, non-mutagenic drug-tolerant state to endure the treatment underlying the minimal residual disease and tumour relapse. Drug tolerance to sunitinib remains largely unexplored in RCC. Here, we show that sunitinib-tolerant 786-O/S and Caki-2/S cells are induced by prolonged drug treatment showing reduced drug sensitivity, enhanced clonogenicity, and DNA synthesis. Sunitinib-tolerance developed via dynamic processes, including (i) engagement of c-MET and AXL pathways, (ii) alteration of stress-induced p38 kinase and pro-survival BCL-2 signalling, (iii) extensive actin remodelling, which was correlated with activation of focal adhesion proteins. Remarkably, the acute drug response in both sensitive and sunitinib-tolerant cell lines led to dramatic fine-tuning of the actin-cytoskeleton and boosted cellular migration and invasion, indicating that the drug-response might depend on cell state transition rather than pre-existing mutations. The drug-tolerant state was transiently acquired, as the cells resumed initial drug sensitivity after >10 passages under drug withdrawal, reinforcing the concept of dynamic regulation and phenotypic heterogeneity. Our study described molecular events contributing to the reversible switch into sunitinib-tolerance, providing possible novel therapeutic opportunities in RCC.

CD276 enhances sunitinib resistance in clear cell renal cell carcinoma by promoting DNA damage repair and activation of FAK-MAPK signaling pathway.

OBJECTIVE: This study aimed to explore the effect of CD276 expression on the sunitinib sensitivity of clear cell renal cell carcinoma (ccRCC) cell and animal models and the potential mechanisms involved. METHODS: CD276 expression levels of ccRCC and normal samples were analyzed via online databases and real-time quantitative PCR (RT-qPCR). CD276 was knocked down in ccRCC cell models (sunitinib-resistant 786-O/R cells and sunitinib-sensitive 786-O cells) using shRNA transfection, and the cells were exposed to a sunitinib (2 µM) environment. Cells proliferation was then analyzed using MTT assay and colony formation experiment. Alkaline comet assay, immunofluorescent staining, and western blot experiments were conducted to assess the DNA damage repair ability of the cells. Western blot was also used to observe the activation of FAK-MAPK pathway within the cells. Finally, a nude mouse xenograft model was established and the nude mice were orally administered sunitinib (40 mg/kg/d) to evaluate the in vivo effects of CD276 knockdown on the therapeutic efficacy of sunitinib against ccRCC. RESULTS: CD276 was significantly upregulated in both ccRCC clinical tissue samples and cell models. In vitro experiments showed that knocking down CD276 reduced the survival rate, IC50 value, and colony-forming ability of ccRCC cells. Knocking down CD276 increased the comet tail moment (TM) values and γH2AX foci number, and reduced BRCA1 and RAD51 protein levels. Knocking down CD276 also decreased the levels of p-FAK, p-MEK, and p-ERK proteins. CONCLUSION: Knocking down CD276 effectively improved the sensitivity of ccRCC cell and animal models to sunitinib treatment.