Resistance to sunitinib in renal cell carcinoma: From molecular mechanisms to predictive markers and future perspectives

The introduction of agents that inhibit tumor angiogenesis by targeting vascular endothelial growth factor (VEGF) signaling has made a significant impact on the survival of patients with metastasized renal cell carcinoma (RCC). Sunitinib, a tyrosine kinase inhibitor of the VEGF receptor, has become the mainstay of treatment for these patients. Although treatment with sunitinib substantially improved patient outcome, the initial success is overshadowed by the occurrence of resistance. The mechanisms of resistance are poorly understood. Insight into the molecular mechanisms of resistance will help to better understand the biology of RCC and can ultimately aid the development of more effective therapies for patients with this infaust disease. In this review we comprehensively discuss molecular mechanisms of resistance to sunitinib and the involved biological processes, summarize potential biomarkers that predict response and resistance to treatment with sunitinib, and elaborate on future perspectives in the treatment of metastasized RCC.

Abstract 1272: Alcohol and dietary folate intake and gene promoter methylation in clear-cell renal cell cancer

Introduction: High intake of alcohol and low intake of folate have been associated with gene promoter methylation. Increased promoter methylation of tumor suppressor genes plays an important role in renal cell cancer (RCC). On the other hand, however, alcohol intake is associated with a decreased risk of RCC risk in most prospective studies. We therefore investigated whether alcohol and dietary folate intakes were associated with gene promoter methylation in RCC.

Methods: The Netherlands Cohort Study (NLCS) with case-cohort design included 120,852 subjects aged 55-69 years in 1986. Diet was measured with a food-frequency questionnaire. After 20.3 years of follow-up, paraffin-embedded tumor blocks were collected from 454 incident RCC cases, of which 80% had clear cell (cc) histology. Methylation-specific PCR (MSP) was used to analyze promoter CpG island methylation in tumor DNA. Genes were selected that were known to be involved in ccRCC. Furthermore, genes were selected exhibiting 1) promoter CpG island methylation in ccRCC cell lines and not in normal kidney tissue in a genome-wide methylation screen (MBD-affinity massive parallel sequencing) and 2) ccRCC-specific down-regulation in the TCGA data. In total, we identified 14 genes (CDO1, CFTR, CSPG4, FST, FZD10, GAL, GRE1, LAD1, NEFH, NEURL, RASGFR2, SFN, SFRP1, VHL) as candidate markers. We computed a sum score of methylated genes and divided the ccRCC cases into those with low- (0-18% of the genes methylated), intermediate- (20-45%) and high- (46-100%) methylated tumors. Multivariable analyses were conducted using Cox regression analyses, stratified according to methylation sum score and included 4,439 subcohort members and 300 ccRCC cases.

Results: Prevalence of gene promoter methylation was on average 36%, but varied from 7.8% (VHL) to 96.5% (SFN).

Increasing intakes of alcohol were associated with decreased risk in all ccRCC cases, but not statistically significant: multivariable adjusted HR (95% CI) for ≥15g alcohol/day vs. 0 g/day 0.79 (0.54-1.16), and p for trend 0.44. In strata of ccRCC according to methylation sum score no significant heterogeneity was observed, although the HR for ≥ 15g alcohol/day versus 0 g/day was significantly decreased in ccRCC with a high methylation sum score: 0.36 (95% CI 0.14-0.93), p for trend, 0.14.

Dietary intake of folate was not associated with ccRCC risk: HR for the quintile of highest intake versus lowest intake: 1.07 (CI, 0.70-1.64) and p for trend, 0.59. Between strata of ccRCC cases according to methylation sum score no significant heterogeneity was observed. There was no effect-modification of alcohol and dietary folate intake on overall ccRCC risk, nor in strata according to methylation sum score.

Conclusion: Our findings show that alcohol and dietary folate intake are not associated with ccRCC risk, neither overall nor in strata according to methylation sum score.

Citation Format: Leo J. Schouten, Ivette A.G. Deckers, Piet A. van den Brandt, Patricia M.M.B. Soetekouw, Marcella M.M.L. Baldewijns, Manon van Engeland. Alcohol and dietary folate intake and gene promoter methylation in clear-cell renal cell cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1272. doi:10.1158/1538-7445.AM2014-1272

A QTc study of cabazitaxel in patients with advanced solid tumors

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Background: Cabazitaxel (Cbz) improves overall survival in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) after docetaxel failure, compared with mitoxantrone (HR 0.70; 95% CI 0.59–0.83; p<0.0001). Following Cbz approval for the treatment of mCRPC, this study was undertaken to evaluate any effect of Cbz on the QTc interval. Methods: This prospective, multinational, open-label study (NCT01087021) enrolled pts with advanced solid tumors (without other therapeutic options). Cbz 25 mg/m² IV was administered on Day 1 Q3W. QTc and other ECG intervals were assessed on Day 1 of Cycle 1. Triplicate ECGs were obtained from 12-lead Holter recordings and concomitant serial blood samples were collected for pharmacokinetic (PK) analysis. The primary endpoint was change from baseline in the corrected QTc interval (according to the Fridericia formula [QTcF]). Results: A total of 96 pts were enrolled; 32 pts under the original protocol (6-h Holter) and 64 pts following protocol amendment 1, which extended ECG and PK monitoring (24-h Holter). Median age was 63 yrs (69.8% male), 30.5% and 57.9% of pts were ECOG PS 0 and 1 respectively; 33 pts (34.4%) had prostate cancer. Screening ECG was abnormal but not clinically significant in 39.6% of pts. The majority (n=65) of pts received ≥ 3 treatment cycles; safety and ECG parameters were evaluated in 95 and 94 pts, respectively. In the 24-h Holter group (n=63), the maximum least squares (LS) mean change from baseline in QTcF was 4.8 msec (90% CI 2.1–7.5), returning to baseline by 24 h. Similar results were observed in the overall population (n=94). At Cmax, Cbz concentration had no effect on QTcF change from baseline; the mean (CV%) Cmax (n=91) and AUC (n=92) were 276 ng/ml (63%) and 1245 ng.h/ml (82%). The LS mean change from baseline in heart rate increased up to 24 h but remained < 10 beats per minute. The most common grade 3/4 AEs were neutropenia (27.4%), febrile neutropenia (12.6%), fatigue (12.6%) and dehydration (5.3%). No grade 3/4 cardiac AEs were reported. Of the 6 deaths reported, 1 (infection) was study drug related. Conclusions: Cbz had no significant effect on QTc interval in pts with advanced tumors. The Cbz safety profile is consistent with previous findings and with other taxane-based therapies.

A QTc study of cabazitaxel in patients with advanced solid tumors

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Background: Cabazitaxel (Cbz) improves overall survival in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) after docetaxel failure, compared with mitoxantrone (HR 0.70; 95% CI 0.59–0.83; P < 0.0001). Following Cbz approval for the treatment of mCRPC, this study was undertaken to evaluate any effect of Cbz on the QTc interval.

Methods: This prospective, multinational, open-label study ( NCT01087021 ) enrolled pts with advanced solid tumors (without other therapeutic options). Cbz 25 mg/m² IV was administered on Day 1 Q3W. QTc and other ECG intervals were assessed on Day 1 of Cycle 1. Triplicate ECGs were obtained from 12-lead Holter recordings and concomitant serial blood samples were collected for pharmacokinetic (PK) analysis. The primary endpoint was change from baseline in the corrected QTc interval (according to the Fridericia formula QTcF).

Results: A total of 96 pts were enrolled; 32 pts under the original protocol (6-h Holter) and 64 pts following protocol amendment 1, which extended ECG and PK monitoring (24-h Holter). Median age was 63 yrs (69.8% male), 30.5% and 57.9% of pts were ECOG PS 0 and 1 respectively; 33 pts (34.4%) had prostate cancer. Screening ECG was abnormal but not clinically significant in 39.6% of pts. The majority (n = 65) of pts received ≥ 3 treatment cycles; safety and ECG parameters were evaluated in 95 and 94 pts, respectively. In the 24-h Holter group (n = 63), the maximum least squares (LS) mean change from baseline in QTcF was 4.8 msec (90% CI 2.1–7.5), returning to baseline by 24 h. Similar results were observed in the overall population (n = 94). At Cmax, Cbz concentration had no effect on QTcF change from baseline; the mean (CV%) Cmax (n = 91) and AUC (n = 92) were 276 ng/ml (63%) and 1245 ng.h/ml (82%). The LS mean change from baseline in heart rate increased up to 24 h but remained < 10 beats per minute. The most common Grade 3/4 AEs were neutropenia (27.4%), febrile neutropenia (12.6%), fatigue (12.6%) and dehydration (5.3%). No Grade 3/4 cardiac AEs were reported. Of the 6 deaths reported, 1 (infection) was study drug related.

Conclusions: Cbz had no significant effect on QTc interval in pts with advanced tumors. The Cbz safety profile is consistent with previous findings and with other taxane-based therapies.

Natural course of symptoms in Cambodia veterans: a follow-up study

BACKGROUND

Dutch (ex-)servicemen were deployed in the 1992-3-peace operation UNTAC in Cambodia. Since their return, they have voiced concerns about the health consequences of their service and they have reported symptoms such as fatigue and cognitive problems. The natural course of symptoms in Dutch Cambodia veterans was evaluated in a prospective study.

METHODS

At 18-months follow-up, a questionnaire was sent to 354 veterans who met a set case definition for symptoms in Cambodia veterans or who had sub-threshold scores. Initial measurement of fatigue severity, psychological well-being, depression, post-traumatic stress disorder, trait-anxiety, self-efficacy and causal attributions, was used to evaluate predictors for self-reported improvement and low levels of fatigue at follow-up.

RESULTS

At follow-up, 19% of the respondents reported complete recovery, 20% felt much better, 57% had the same complaints and 4% had become worse compared with their initial assessment. Self-reported improvement and less severe fatigue at follow-up were predicted by less severe fatigue at initial assessment and more perceived control over symptoms.

CONCLUSIONS

Self-reported improvement was reported in a considerable percentage of Cambodia veterans, whereas another substantial percentage of Cambodia veterans continued to suffer with severe levels of fatigue and related symptoms. Predictors of improvement in Cambodia veterans and patients with chronic fatigue syndrome show similarities and also seem to bear importance for Gulf War veterans.

Normal carnitine levels in patients with chronic fatigue syndrome

BACKGROUND

Patients with chronic fatigue syndrome (CFS) complain of muscle pain and impaired exercise tolerance. Previous studies show that this is due to systemic carnitine deficiency. We investigated the hypothesis that carnitine deficiency plays an important role in CFS in female CFS patients and compared their results with neighbourhood controls.

METHODS

The level of total carnitine, free carnitine, acylcarnitine and carnitine esters were measured in 25 female CFS patients and 25 healthy matched neighbourhood controls in a blinded fashion.

RESULTS

The previously reported decreased level of acylcarnitine in CFS patients was not confirmed. There were also no significant differences in levels of total carnitine, free carnitine and 20 carnitine esters between CFS patients and controls.

CONCLUSIONS

The present study demonstrates that serum carnitine deficiency does not contribute to or causes the symptoms in many CFS patients.

Somatic hypotheses of war syndromes

Since the end of the American Civil War, unexplained symptoms in military personnel arising after a war or peace mission have frequently been described. The pattern of symptoms is highly similar for all of the various war syndromes although the conditions of each war or peace mission are widely different. Many somatic hypotheses have been formulated to explain these syndromes; a considerable proportion of them are already outdated. In the last few years much attention has been given to Gulf War Syndrome and to unexplained symptoms of military personnel who were sent to Cambodia, Rwanda, Burundi, Zaire, or the former Yugoslavia. In this review the symptoms of war syndromes will be considered in more detail and the suggested somatic explanations will be discussed. During the last decade the following somatic causes have been suggested as possible explanations for these symptoms: (persistent) infection, abnormal immune response, administration of multiple vaccinations within a short period of time, use of malaria chemoprophylaxis, neurological abnormalities, exposure to toxicological substances and environmental factors. The various investigations performed to study these hypotheses are discussed. The fact that bias regularly occurs in the course of these investigations is pointed out. For the future, a reliable investigation of a war syndrome should be a prospective multidisciplinary study and should distinguish between causative and sustaining factors.

Fatigue in Cambodia veterans

In 1992 and 1993, Dutch military personnel were deployed in the peace operation UNTAC in Cambodia. Since returning, Cambodia veterans have reported health complaints which they perceive to be related to their service. Their symptoms strikingly resemble health problems reported by Gulf War veterans. Four years post-return, a cross-sectional survey on health symptoms in Cambodia veterans was initiated. Questionnaires were sent to all Cambodia veterans and four comparison groups. Forgetfulness, difficulty concentrating and fatigue were the symptoms most commonly endorsed. An operational case definition was constructed using a validated fatigue severity questionnaire. Cases were not uniquely found in Cambodia veterans (17%). In Rwanda and Bosnia veterans, respectively, 28% and 11% also met our case definition. Fatigue severity level was predicted by pre-mission, during-mission and post-mission variables, of which retrospective recollection of side-effects of vaccines and causal attributions also have been shown to be relevant in studies on Gulf-related illness.

[Somatic and psychological symptoms in soldiers after military clashes and peace-keeping missions]

Dutch soldiers who have participated in the peace keeping operation United Nations Transitional Authority in Cambodia (UNTAC) have reported various somatic and psychological symptoms since their return. Their symptoms show similarities to the Gulf War Syndrome. The question arises whether Gulf War Syndrome, symptoms in UNTAC soldiers and other symptoms after acts of war and peace operations are unique syndromes or comparable complaints? From an historical overview it is not plausible that new and unique syndromes will occur with each war or peace operation. On the other hand it also seems unlikely that war syndromes can be reduced to one diagnostic category. The post-Cambodia complaints may be described in four hypothetical models: the somatic start model, the psychotrauma start model, the premorbidity model and the complaints-not-related-to-Cambodia model. These models are expected to be applicable, after further validation, to other symptoms after acts of war and peace operations. Also they will provide points of application for prevention and treatment of symptoms after future wars and peace operations.

Autonomic function in patients with chronic fatigue syndrome

Subtle signs of autonomic dysfunction and orthostatic intolerance have been reported in patients with chronic fatigue syndrome (CFS). To assess cardiovascular autonomic function noninvasively in an unselected group of patients with CFS, we examined responsiveness to several cardiovascular reflex tests in 37 CFS patients and 38 healthy control subjects. Blood pressure and heart rate (HR) were recorded continuously by a Finapres device before and during forced breathing, standing up, Valsalva maneuver, and sustained handgrip exercise (HG). In addition, a mental arithmetic test was carried out and questionnaires to assess the severity of CFS symptoms were completed. At rest, there were no significant differences in blood pressure or in HR between the two groups. The in- and expiratory difference in HR tended to be lower in CFS patients (28.4 +/- 10.5 beats) than in healthy controls (32.2 +/- 9.5) (p = 0.11). The maximal increase in HR during standing up was not significantly different between the CFS group (37.6 +/-8.9 beats) and the control group (40.2 +/- 8.9 beats). There were no significant differences between both groups with regard to the Valsalva ratio, but the systolic and diastolic blood pressure responses were significantly larger in CFS patients, despite the fact that many CFS patients were not able to sustain the Valsalva maneuver. The HR response to MA was significantly less in the CFS group (22.6 +/- 9.9) than in the control group (29.5 +/- 16.7) (p < 0.05), suggesting impaired cardiac sympathetic responsiveness to mental stress. The lower HR responses could not be explained by the level of concentration in the CFS group. During HG exercise, the hemodynamic responses were lower in the CFS group than in the control group, but this might be attributed to the lower level of muscle exertion in CFS patients. There were no significant differences between CFS patients with and without symptoms of autonomic dysfunction regarding the hemodynamic responses to the cardiovascular reflex tests. The findings of the study suggest that there are no gross alterations in cardiovascular autonomic function in patients with CFS.

Persistent symptoms in former UNTAC soldiers are not associated with shifted cytokine balance

BACKGROUND

The pathogenesis of post-combat syndromes, such as Gulf War syndrome, is poorly understood. Recently, it has been postulated that the symptoms of veterans with such syndromes are due to a disturbed cytokine balance shifted towards a T-helper (Th) 2 profile. We investigated this hypothesis in 21 symptomatic former UNTAC soldiers and compared their results with those obtained in 21 healthy former UNTAC soldiers matched for age, sex and military force.

DESIGN

The numbers of intracellular interleukin 4 (IL-4) and interferon gamma- (IFN-gamma) producing CD4+ and CD8+ T lymphocytes (CD3+) were determined after in vitro stimulation with phorbol myristate acetate and calcium ionophore in the presence of brefeldin to block secretion of induced cytokines. Circulating concentrations and lipopolysaccharide- (LPS) or phytohaemagglutinin- (PHA) stimulated whole-blood production of the proinflammatory cytokines IL-1beta, IL-1ra, tumour necrosis factor alpha (TNF-alpha) and IL-10 and IFN-gamma were measured.

RESULTS

The numbers of CD4+ and CD8+ T lymphocytes positive for IL-4 or IFN-gamma production were not significantly different in patients and control subjects. After stimulation with LPS or PHA, the in vivo circulating concentration and concentration of IL-10 and IFN-gamma were also similar.

CONCLUSIONS

The present study demonstrates that there is no shift in cytokine balance towards a Th2 profile in former UNTAC soldiers with symptoms similar to those of the Gulf War syndrome.