Renal cell carcinoma: what does the future hold

1. Renal cell carcinoma: what does the future hold? Floriana Morgillo, MD PhD Second University of Naples

2. Epidemiology 2007 51,190 diagnosis 12,890 deaths Incidence increased of 2% per year 5-year survival from 5% to 10% in advanced stage In 2007, it is estimated that 51,190 people will be diagnosed with and 12,890 deaths will be attributed to cancers of the kidney and renal pelvis (the vast majority of which are renal cell carcinoma [RCC]) in the United States.1 During the past 2 decades, the incidence of these cancers has increased by approximately 2% per year.2 RCC represents the third leading cause of death among genitourinary malignancies and the twelfth leading cause of cancer death overall in the United States. 1 The lack of demonstrable efficacy of chemotherapy and radiation therapy in Stage IV RCC has led to a 5-year survival ranging from 5% to 10%.In 2007, it is estimated that 51,190 people will be diagnosed with and 12,890 deaths will be attributed to cancers of the kidney and renal pelvis (the vast majority of which are renal cell carcinoma [RCC]) in the United States.1 During the past 2 decades, the incidence of these cancers has increased by approximately 2% per year.2 RCC represents the third leading cause of death among genitourinary malignancies and the twelfth leading cause of cancer death overall in the United States. 1 The lack of demonstrable efficacy of chemotherapy and radiation therapy in Stage IV RCC has led to a 5-year survival ranging from 5% to 10%.

3. What did the past give? Cytoreductive nephrectomy two identically designed, prospective randomized clinical trials were initiated in Europe and the United States When the data from these two studies are combined, they provide strong support favoring the use of nephrectomy before immunotherapy. Cytoreductive nephrectomy has thus been translated into routine clinical practice two identically designed, prospective randomized clinical trials were initiated in Europe and the United States When the data from these two studies are combined, they provide strong support favoring the use of nephrectomy before immunotherapy. Cytoreductive nephrectomy has thus been translated into routine clinical practice

4. The Cytokine Era Over the past 2 decades, immunotherapeutic approaches implementing biologic response modifiers like IFN-� and IL-2 alone or in combination have been the standard treatment for patients with advanced RCC. Table 2 summarizes relevant trials evaluating cytokines in advanced RCC. Taken together, these data suggest that HD IL-2 has a higher overall and complete response rate compared with low-dose therapy, with the majority of benefit realized in the durability of complete responses. There is no proven benefit, however, in disease-free or overall survival with HD IL-2 for the entire cohort. Toxicity is substantial with HD IL-2 and highlights the need for stringent patient selection. The median survival improvement with IFN-� treatment versus control was 3.8 months (P _ 0.007), Although cytokines retain modest antitumor activity in RCC, further use of these agents should occur in the context of clinical trials that investigate susceptible patient populations and/or combination therapy with anti-VEGF or other agents Over the past 2 decades, immunotherapeutic approaches implementing biologic response modifiers like IFN-� and IL-2 alone or in combination have been the standard treatment for patients with advanced RCC. Table 2 summarizes relevant trials evaluating cytokines in advanced RCC. Taken together, these data suggest that HD IL-2 has a higher overall and complete response rate compared with low-dose therapy, with the majority of benefit realized in the durability of complete responses. There is no proven benefit, however, in disease-free or overall survival with HD IL-2 for the entire cohort. Toxicity is substantial with HD IL-2 and highlights the need for stringent patient selection. The median survival improvement with IFN-� treatment versus control was 3.8 months (P _ 0.007), Although cytokines retain modest antitumor activity in RCC, further use of these agents should occur in the context of clinical trials that investigate susceptible patient populations and/or combination therapy with anti-VEGF or other agents

5. THE ROLE OF VEGF IN RENAL CELL CARCINOMA

6. Both sporadic and inherited forms of clear cell renal carcinoma are associated to mutations of VHL gene. The VHL gene product has been found in a multiprotein complex which regulates the function of the transcription factor 1 (HIF1) by ubiquitination. In normal conditions or normoxia, HIF1 A is hydroxilated and ubiquitinated by VHL and directed in the proteasomal degradation. In hypoxia o in VHL mutation, HIF1A is not anymore hydroxilated and can bind to the subunit B and then translocate into the nucleus to activate the transcription of several gene implicated in the response to hypoxia stress, such as EGFR, VEGFR, PDGF, TGFA, GLUT-1, EPO, which regulate cell growth, angiogenesis, glucose metabolism and Ph.Both sporadic and inherited forms of clear cell renal carcinoma are associated to mutations of VHL gene. The VHL gene product has been found in a multiprotein complex which regulates the function of the transcription factor 1 (HIF1) by ubiquitination. In normal conditions or normoxia, HIF1 A is hydroxilated and ubiquitinated by VHL and directed in the proteasomal degradation. In hypoxia o in VHL mutation, HIF1A is not anymore hydroxilated and can bind to the subunit B and then translocate into the nucleus to activate the transcription of several gene implicated in the response to hypoxia stress, such as EGFR, VEGFR, PDGF, TGFA, GLUT-1, EPO, which regulate cell growth, angiogenesis, glucose metabolism and Ph.

7. Moreover HIF1A is also regulated by growth factor such as EGF or VEGF which binding their corrispective receptor activte the downstream cascade, in particular PI3K/Akt, Raf-ras-MAPK and MTOR. Moreover HIF1A is also regulated by growth factor such as EGF or VEGF which binding their corrispective receptor activte the downstream cascade, in particular PI3K/Akt, Raf-ras-MAPK and MTOR.

8. Monotherapy Trials The biology of VEGF and overexpression in RCC has led to the development of several novel therapeutic strategies to inhibit this pathway. Phase II and III data with bevacizumab , sorafenib and sunitinib show that each of these anti-VEGF agents is effective as monotherapy in cytokine refractory metastatic RCC. Bevacizumab demonstrated a TTP significantly longer than placebo (4.8 m vs 2.5), and a following study the monotherapy with Bev in first-line demonstrated a PFS of 8.5 and an ORR of 13%. Sunitinib provides a clear and unequivocal improvement over interferon alfa in untreated RCC pts who have favourable or intermediate prognostic features according to the MSKCC classification. On the other side a phase II study of first line with sorafenib vs IFNA failed to demonstrate an advantega in terms of PFR , thus sorafenib is not indicated in front line setting , except for those pts who cannot tolerate sunitinib. The biology of VEGF and overexpression in RCC has led to the development of several novel therapeutic strategies to inhibit this pathway. Phase II and III data with bevacizumab , sorafenib and sunitinib show that each of these anti-VEGF agents is effective as monotherapy in cytokine refractory metastatic RCC. Bevacizumab demonstrated a TTP significantly longer than placebo (4.8 m vs 2.5), and a following study the monotherapy with Bev in first-line demonstrated a PFS of 8.5 and an ORR of 13%. Sunitinib provides a clear and unequivocal improvement over interferon alfa in untreated RCC pts who have favourable or intermediate prognostic features according to the MSKCC classification. On the other side a phase II study of first line with sorafenib vs IFNA failed to demonstrate an advantega in terms of PFR , thus sorafenib is not indicated in front line setting , except for those pts who cannot tolerate sunitinib.

9. Combination Therapy Preclinical rationale PDGF-A, PDGF-B, TGF-a, EPO are overexpressed in pericytes and renal epithelial cancer cells Targeting VEGF, VEGFR-2 and Tie2 with immunotherapy (dendridic cells) lead to synergistic activity IFN-a has demonstrated an antiangiogenic activity Sorafenib and sunitinib reduced immunosuppressive T regulatory cell The rationale for targeting VEGF in RCC is strong; other factors however are upregulated in RCC such as PDGF-B, TGFA, EPO. These receptors are expressed at high level in the pericites supporting tumor vasculature and in renal epithelial cancer cell. Therefore, enhanced antitumor activity may be achieved by both targeting VEGF and PDGF signalling. Various preclinical studies say that IFN has also an antiangiogenic activity and combining two agents with antiangiogenis activity may result in a synergistic effect. Studies suggest that sorafenib and sunitinb are able to inhibit immunosuppressive T regulatory cells. Taken together these data support potential immunomodulatory effects of targeted agents in RCC opening the door to several combination strategies. The rationale for targeting VEGF in RCC is strong; other factors however are upregulated in RCC such as PDGF-B, TGFA, EPO. These receptors are expressed at high level in the pericites supporting tumor vasculature and in renal epithelial cancer cell. Therefore, enhanced antitumor activity may be achieved by both targeting VEGF and PDGF signalling. Various preclinical studies say that IFN has also an antiangiogenic activity and combining two agents with antiangiogenis activity may result in a synergistic effect. Studies suggest that sorafenib and sunitinb are able to inhibit immunosuppressive T regulatory cells. Taken together these data support potential immunomodulatory effects of targeted agents in RCC opening the door to several combination strategies.

10. Addition of Bevacizumab to IFN-a Addition of Bev to IFN has been evaluated in a phase III study (AVOREN) in first line demonstrating a an improvement in tumor response rate and PFS if compared to IFN alone. Addition of Bev to IFN has been evaluated in a phase III study (AVOREN) in first line demonstrating a an improvement in tumor response rate and PFS if compared to IFN alone.

12. Another trial will provide more information about the efficacy of Bev in front-line, although will not fully define the additive or synergistic activity of the combination due to the lack of a single control arm Bev Another trial will provide more information about the efficacy of Bev in front-line, although will not fully define the additive or synergistic activity of the combination due to the lack of a single control arm Bev

13. Gollob et al. Phase II 1-2� line Sorafenib 400 mg po bid plus IFN- 10MU sc. tiw 24 pts evaluable RR 42% Additional trial are investigatin sorafenib in combination with IFNA. Preliminary data are from the ASCO meeting 2006 giving a preliminary ORR ranging from 42 to 19%. From the ASCO2007, the addition of sorafenib to IFNA in frontline gave a ORR of 25%. Ongoing trials are evaluating the addition of sunitinib to IFNA.Additional trial are investigatin sorafenib in combination with IFNA. Preliminary data are from the ASCO meeting 2006 giving a preliminary ORR ranging from 42 to 19%. From the ASCO2007, the addition of sorafenib to IFNA in frontline gave a ORR of 25%. Ongoing trials are evaluating the addition of sunitinib to IFNA.

14. Combination therapy in RCC The feasibility of combining VEGF-targeting approaches is also being studied. The feasibility of combining VEGF-targeting approaches is also being studied.

15. Studies tesing the combination of Bev and sorafenib or sunitinib are ongoing. In a phase I study of Bev + Sor with a dose escalation design there was a preliminary evidence of antitumor activity, although the full dose of each drug were not reached due to the DLT related, as HFS, anorexia and fatigue.Studies tesing the combination of Bev and sorafenib or sunitinib are ongoing. In a phase I study of Bev + Sor with a dose escalation design there was a preliminary evidence of antitumor activity, although the full dose of each drug were not reached due to the DLT related, as HFS, anorexia and fatigue.

16. Another approach examined anti �VEGF agents combined with anti EGFR agents. We know that EGFR and its ligand, TGFA, is overexpressed in RCC, and we also know that inhibition of EGFR by TKI or MAb reduce VEGF levels and microvessel density. Interestingly, tumor cells with acquired resistance to anti-EGFR drugs exibit increased expression and secretion of VEGFR. These data suggest that inhibiton of EGFR-dependent angiogenesis is important for the antitumor activity of anti-EGFR drugs and angiogenesis itself is one of the most important causes of resistance to anti-EGFR drugs. Therefore, is not surprising that the combination of drugs targeting both targets has showed greatr antituomr activity in several human cancers. Another approach examined anti �VEGF agents combined with anti EGFR agents. We know that EGFR and its ligand, TGFA, is overexpressed in RCC, and we also know that inhibition of EGFR by TKI or MAb reduce VEGF levels and microvessel density. Interestingly, tumor cells with acquired resistance to anti-EGFR drugs exibit increased expression and secretion of VEGFR. These data suggest that inhibiton of EGFR-dependent angiogenesis is important for the antitumor activity of anti-EGFR drugs and angiogenesis itself is one of the most important causes of resistance to anti-EGFR drugs. Therefore, is not surprising that the combination of drugs targeting both targets has showed greatr antituomr activity in several human cancers.

17. Following this rationale a phase II study has been conducted in 104 pts with RCC in front-line using Bev in combination with Erl or Bev alone. In this study the addition of erloitnib to Bev was well tolerated but did not provide additional clinical benefit compare dwith Bev alone in terms of PFS or ORR. Although the addition of Bev to Erl did not demonstrate clinical benefit if compared to Bev alone, it did showed potential clinical activity of Bev with regard to PFS . The Bev arm Had a median PFS of 8.5 months and in particular in pts at low and intermediate risk, in accord to the MSKCC criteria, the PFS were 13.1 and 7.3 m compared to the IFN of 8.3 and 5.1 m, respectively. Following this rationale a phase II study has been conducted in 104 pts with RCC in front-line using Bev in combination with Erl or Bev alone. In this study the addition of erloitnib to Bev was well tolerated but did not provide additional clinical benefit compare dwith Bev alone in terms of PFS or ORR. Although the addition of Bev to Erl did not demonstrate clinical benefit if compared to Bev alone, it did showed potential clinical activity of Bev with regard to PFS . The Bev arm Had a median PFS of 8.5 months and in particular in pts at low and intermediate risk, in accord to the MSKCC criteria, the PFS were 13.1 and 7.3 m compared to the IFN of 8.3 and 5.1 m, respectively.

18. Other promising target is MTOR, a large polypeptide kinase, downstream component in the PI3K/Akt pathway, which act by regulating translation, protein degradation, and protein signalling. VEGF-mediating endothelial cell proliferation requires the PI3K activity. MTOR has also been identified as an upstream activator of HIF1 which prevents his degradation.Other promising target is MTOR, a large polypeptide kinase, downstream component in the PI3K/Akt pathway, which act by regulating translation, protein degradation, and protein signalling. VEGF-mediating endothelial cell proliferation requires the PI3K activity. MTOR has also been identified as an upstream activator of HIF1 which prevents his degradation.

19. Tensirolimus, a specific inhibitor of MTOR, has been evaluated versus IFN or in combination with IFN as first-line in pts with advanced RCC, demonstrating a longer OS and PFS than IFN, with no additive effect in the combination arm. This study involved pts with extensive metastatic disease and several adverse prognostic markers. Treatment with tensirolimus was associated with a moderate prolongation of survival in this class of pts becoming the drug of choice in this poor-risk pts.Tensirolimus, a specific inhibitor of MTOR, has been evaluated versus IFN or in combination with IFN as first-line in pts with advanced RCC, demonstrating a longer OS and PFS than IFN, with no additive effect in the combination arm. This study involved pts with extensive metastatic disease and several adverse prognostic markers. Treatment with tensirolimus was associated with a moderate prolongation of survival in this class of pts becoming the drug of choice in this poor-risk pts.

20. Several other novel agents have shown preclinical and clinical activityb in advanced RCC are now being tested in clinical studies .Several other novel agents have shown preclinical and clinical activityb in advanced RCC are now being tested in clinical studies .

21. Sequenced therapy Questions about efficacy of sequenced approaches have emerged as resistance to these agents develops. Resistance to or failure of antiangiogenic agents is defined by evidence of progression deisease by RECIST criteria. Obviously not all resistance are identical. A subset of patients fails to achieve any tumor shrinkage by therapy and progress rapidly. Other pts shows a minor response and progress abyway; other pts experience a dramatic tumor shrinkage and a prolonged antitumor effect followed by a slow progression. These pts are clinically and biologically different from others and might benefit of sequential treatment. Sunitinib has been investigated in Bev resistant population showing an ORR of 23% and an overall tumor shrinkage of 74% supporting the clinical hypotesis that VEGF and recetor signalling are still relevant after the VEGF liand blockade. Questions about efficacy of sequenced approaches have emerged as resistance to these agents develops. Resistance to or failure of antiangiogenic agents is defined by evidence of progression deisease by RECIST criteria. Obviously not all resistance are identical. A subset of patients fails to achieve any tumor shrinkage by therapy and progress rapidly. Other pts shows a minor response and progress abyway; other pts experience a dramatic tumor shrinkage and a prolonged antitumor effect followed by a slow progression. These pts are clinically and biologically different from others and might benefit of sequential treatment. Sunitinib has been investigated in Bev resistant population showing an ORR of 23% and an overall tumor shrinkage of 74% supporting the clinical hypotesis that VEGF and recetor signalling are still relevant after the VEGF liand blockade.

22. Clinical end-points RECIST Block the tumor growth rather than tumor regression Response-independent survival benefit PFS The traditional approach of measuring RECIST-defined response rate may not be the most appropriate design for evaluate anti-VEGF agents that may contribute to inhibit tumor growth rather than promoting frank tumor regression, and it is of note that a response-independent survival benefit has been observed with bev in other tumors. Thus for some agents a randomize comparison with a PFS end point mat needed to identify a signal of activity for further investigation The traditional approach of measuring RECIST-defined response rate may not be the most appropriate design for evaluate anti-VEGF agents that may contribute to inhibit tumor growth rather than promoting frank tumor regression, and it is of note that a response-independent survival benefit has been observed with bev in other tumors. Thus for some agents a randomize comparison with a PFS end point mat needed to identify a signal of activity for further investigation

23. Patients selection Non-clear cell carcinoma By preselecting pts most likely to respond to anti-VEGF therapy, such agents could be optimized in the clinical setting. Clear cell histology has been an inclusion criteria in almost all trials, based on the biology of VHL inactivation and subsequent VEGF overexpression, which is confined to this histology. There have been, however, anedoctal reports of activity of these agents in pts with non-clear histology. Any activity of these drugs in non-clear cell RCC underscores the complex biology of RCC and the fact that it is not only VHL inactivation that drives VEGF expression.By preselecting pts most likely to respond to anti-VEGF therapy, such agents could be optimized in the clinical setting. Clear cell histology has been an inclusion criteria in almost all trials, based on the biology of VHL inactivation and subsequent VEGF overexpression, which is confined to this histology. There have been, however, anedoctal reports of activity of these agents in pts with non-clear histology. Any activity of these drugs in non-clear cell RCC underscores the complex biology of RCC and the fact that it is not only VHL inactivation that drives VEGF expression.

24. Predictive biomarkers of response Predictive markes of response are also required. VEGF is an obvious candidate and there is correlation between VEGF levels and poor prognosis in many tumor types and in RCC Predictive markes of response are also required. VEGF is an obvious candidate and there is correlation between VEGF levels and poor prognosis in many tumor types and in RCC

25. Soluble VEGF, VEGFR-2 and VEGFR-3 levels correlated modestly with exposure to sunitinib and sorafenib therapy. VEGF levels were increased in pts responding to treatment indicating that tumor regression could be associated with an effective VEGFR regression (as reflected by lower soluble levels of VEGFR2-3- and higher VEGF protein levels). Soluble VEGF, VEGFR-2 and VEGFR-3 levels correlated modestly with exposure to sunitinib and sorafenib therapy. VEGF levels were increased in pts responding to treatment indicating that tumor regression could be associated with an effective VEGFR regression (as reflected by lower soluble levels of VEGFR2-3- and higher VEGF protein levels).

26. To better interpretate the role of these agents in RCC is of importance to select pts basing also on the calss of risk: evidence based medicine says that Tensirolimus is the drug of choice in poor risk RCC pts (in accord to the MSKCC criteria) reserving Bev, Sor and Sun to the low and intermediate call of risk.To better interpretate the role of these agents in RCC is of importance to select pts basing also on the calss of risk: evidence based medicine says that Tensirolimus is the drug of choice in poor risk RCC pts (in accord to the MSKCC criteria) reserving Bev, Sor and Sun to the low and intermediate call of risk.

27. From the past to the future