CCR 20th Anniversary Commentary CCR 20th Anniversary Commentary: Preclinical Study of Proteasome Inhibitor Bortezomib in Head and Neck Cancer Clint T. Allen1, Barbara Conley2, John B. Sunwoo3, and Carter Van Waes1
In a study published in the May 1, 2001, issue of Clinical Cancer Research, Sunwoo and colleagues provided evidence for proteasome inhibition of NF-kB and tumorigenesis, supporting early-phase clinical trials in solid malignancies of the upper aerodigestive tract. Subsequent clinical studies
uncovered a dichotomy of responses in patients with hematopoietic and solid malignancies, and the mechanisms of resistance. Clin Cancer Res; 21(5); 942–3. 2015 AACR. See related article by Sunwoo et al., Clin Cancer Res 2001;7(5) May 2001;1419–28
The transcription factor NF-kB serves as a central mediator of inflammatory and immune processes and is constitutively activated in many solid and hematopoietic malignancies. Although gain- or loss-of-function mutations directly leading to NF-kB activation are rare, genetic alterations of upstream signal and receptor kinases and extracellular signals from a proinflammatory tumor microenvironment can contribute to constitutive NF-kB activity (1). Activation of canonical and noncanonical NF-kB transcriptional activity relies upon proteasome-mediated degradation of ubiquinated cytoplasmic inhibitor-kB, which sequesters NF-kB into the cytoplasm and away from the nucleus. In response to different upstream stimuli, inhibitor-kB kinases phosphorylate inhibitor-kB, leading to its ubiquitination and degradation by the proteasome, freeing NF-kB to translocate into the nucleus. Introduction of a mutant dominant-negative inhibitor-kB abolishes measureable NF-kB activity in malignant cells, supporting the critical role of the proteasome in the regulation of NF-kB activation. Previous preclinical work demonstrating a role for NF-kB in the initiation and progression of head and neck squamous cell carcinomas (HNSCC), a group of highly inflammatory and aggressive malignancies of the upper aerodigestive tract, provided a rationale for investigating different approaches to proteasome inhibition in this disease. The work by Sunwoo and colleagues (2) established the ability of bortezomib (formerly known as PS-341), a first-inclass small-molecule inhibitor of 20S proteasome activity, to achieve significant antitumor effects in both murine and human cell models of HNSCC. This article mechanistically demonstrated reduced tumor cell viability and reduction of primary tumor
growth in both syngeneic and xenograft models via dose-dependent bortezomib inhibition of NF-kB DNA binding and target gene transactivation. This article was groundbreaking for several reasons. Not only did it build upon growing evidence implicating the central role played by NF-kB in the tumorigenesis and progression of HNSCC, it also served as an early example of the ability to use small-molecule inhibitors to specifically alter or block the activity of rationally selected targets that mediate the growth and survival of HNSCC cells. From this and other work demonstrating that NF-kB inhibition resulted in the sensitization of HNSCC cells to TNFa and radiotherapy-induced cell death, a phase I clinical trial combining escalating doses of twice-weekly bortezomib and reirradiation in patients with recurrent HNSCC was pursued (3). This trial revealed transient tumor regression or stable disease in a subset of patients, and despite being unable to administer doses tolerated by patients with multiple myeloma, provided evidence of proteasome inhibition along with altered expression of NF-kB target genes in evaluable tumor biopsies. Although these findings were encouraging, the lack of durable clinical responses despite molecular evidence of on-target bortezomib activity suggested the presence of resistance mechanisms. To better define these mechanisms of therapeutic escape, further study of clinical trial tissue samples revealed inhibition of the canonical NF-kB subunit RelA, but not noncanonical subunits RelB and cRel or components of the MAPK or STAT3 pathways following bortezomib treatment (4). These clinical data were supported by preclinical work published the same year demonstrating enhanced cytotoxicity in an HNSCC cell line relatively resistant to NF-kB inhibition alone with the addition of MAPK pathway blockade (5). Together, these data provided early evidence in HNSCC of targeted therapeutic resistance due to lack of inhibition of coactivated progrowth and prosurvival signaling pathways, a phenomenon now well recognized as a common mechanism of resistance to single-modality targeted therapy in solid tumors. Exploration of upstream genetic alterations or microenvironmental factors leading to the coactivation of NF-kB, MAPK, and STAT3 pathways led many researchers to investigate the potential role of cell surface kinase receptors such as the EGFR. Given existing preclinical and clinical evidence suggesting an additive
1 Head and Neck Surgery Branch, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, Maryland. 2Cancer Diagnosis Program, National Cancer Institute, NIH, Bethesda, Maryland. 3Division of Head and Neck Surgery, Department of Otolaryngology, Stanford University School of Medicine, Stanford, California.
Corresponding Author: Carter Van Waes, NIDCD, NIH, CRC-4732, 10 Center Drive, Bethesda, MD 20892. Phone: 301-402-4216; Fax: 301-402-1140; E-mail: [email protected] doi: 10.1158/1078-0432.CCR-14-2550 2015 American Association for Cancer Research.
942 Clin Cancer Res; 21(5) March 1, 2015
Downloaded from clincancerres.aacrjournals.org on May 10, 2015. © 2015 American Association for Cancer Research.
CCR 20th Anniversary Commentary or synergistic cytotoxic effect with the combination of NF-kB and EGFR targeted therapies, a phase I trial combining bortezomib, the anti-EGFR monoclonal antibody cetuximab, and radiation in patients with previously untreated, advanced-stage HNSCC was initiated (6). However, this clinical trial was halted before accrual was completed because of an unexpectedly high rate of early disease progression in these patients. Molecular evidence from patient tumor biopsies revealed enhanced activation of NF-kB and MAPK pathway elements downstream of EGFR, potentially due to antagonism of radiation-induced EGFR degradation following proteasome inhibition. Given that in vitro and in vivo murine models can be powerful screening tools for different therapies, this result highlights the caution that must be used when extrapolating information gleaned from preclinical work into the rational design of human clinical trials. Evaluation of bortezomib in patients with non–small cell lung cancer (NSCLC) has shown similar mixed results. Several early phase I and II trials combining bortezomib with standard chemotherapeutic or kinase receptor–targeted therapies failed to demonstrate improved disease control or survival (7). In addition, more recent work has demonstrated that initial sensitivity of RAS- and p53-mutant NSCLC cells to bortezomib-induced NF-kB inhibition was subsequently lost due to the development of NFkB–independent resistance mechanisms in vivo (8). Similar to what has been observed in HNSCC, these reports establish a consistent trend of acquired therapeutic resistance to proteasome inhibition alone through unaltered signaling of coactivated progrowth and prosurvival signaling pathways. The story of limited activity of bortezomib monotherapy in the treatment of solid tumors contrasts with the remarkable success bortezomib has shown in the treatment of hematologic malignancies. Given the known role of NF-kB in immune signaling, bortezomib was evaluated early by others as a therapy for different forms of leukemia and lymphoma, and these studies demonstrated constitutive NF-kB activation. Following large, multicenter advanced-phase clinical trials demonstrating improved outcomes compared with existing standard therapies, bortezomib, marketed as Velcade (Millennium), was FDA approved as secondline therapy for refractory mantle cell lymphoma and as first-line therapy for multiple myeloma in 2006 and 2008, respectively (9). Similarly, carflizomib, marketed as Kyprolis (Onyx), was FDA approved in 2012 for the treatment of multiple myeloma that has not shown a response to at least two prior therapies after
demonstrating significant single-agent activity in clinical trials. Mechanistically, the differential success of bortezomib in treating these malignancies may lie, in part, in its ability to effectively modulate the bcl-2 family of apoptosis-regulating proteins, known to be critical for transformed leukocyte proliferation and survival (7). Beginning with the article by Sunwoo and colleagues (2) in 2001 and in work from others, the story of bortezomib in solid and hematologic malignancies has taken divergent courses. Although bortezomib alone demonstrates significant singleagent activity in some hematopoietic cancers, the development of therapeutic resistance due to unaltered signaling through coactivated signaling pathways observed following single-agent bortezomib treatment in solid tumors has mirrored observations made with many different targeted therapies. Nevertheless, this work investigating novel combinations of existing targeted therapies, including bortezomib, holds promise. Enhanced recognition of the ability of bortezomib and its newer analogues to induce altered protein folding responses, and endoplasmic reticulum stress, with subsequent enhancement of tumor cell antigenicity, places proteasome inhibitors in an ideal position to be combined with immunotherapies (10). However, more investigation is needed, given the potential immunosuppressive effects proteasome inhibition may exert on cells of adaptive immunity. Although second-generation proteasome inhibitors are FDA approved for clinical use and also being evaluated for their effectiveness in the treatment of solid tumors, bortezomib remains the subject of continued research given its remarkable clinical activity in hematopoietic malignancies, FDA approval, and encouraging preclinical data as a component of combination therapy in various solid tumor models.
Disclosure of Potential Conflicts of Interest No potential conflicts of interest were disclosed.
Authors' Contributions Conception and design: C.T. Allen, B. Conley, J.B. Sunwoo, C. Van Waes Writing, review, and/or revision of the manuscript: C.T. Allen, B. Conley, J.B. Sunwoo, C. Van Waes Received December 1, 2014; accepted December 3, 2014; published online March 2, 2015.
References 1. DiDonato JA, Mercurio F, Karin M. NF-kB and the link between inflammation and cancer. Immunol Rev 2012;246:379–400. 2. Sunwoo JB, Chen Z, Dong G, Yeh N, Crowl Bancroft C, Sausville E, et al. Novel proteasome inhibitor PS-341 inhibits activation of nuclear factor-kB, cell survival, tumor growth, and angiogenesis in squamous cell carcinoma. Clin Cancer Res 2001; 7:1419–28. 3. Van Waes C, Chang AA, Lebowitz PF, Druzgal CH, Chen Z, Sunwoo JB, et al. Inhibition of nuclear factor-kappaB and target genes during combined therapy with proteasome inhibitor bortezomib and reirradiation in patients with recurrent head-and-neck squamous cell carcinoma. Int J Radiat Oncol Biol Phys 2005;63:1400–12. 4. Allen C, Saigal K, Nottingham L, Arun P, Chen Z, Van Waes C. Bortezomib-induced apoptosis with limited clinical response is accompanied by inhibition of canonical but not alternative nuclear factor{kappa}B subunits in head and neck cancer. Clin Cancer Res 2008; 14:4175–85.
www.aacrjournals.org
5. Chen Z, Rickler JL, Malhotra PS, Nottingham L, Bagain L, Lee TL, et al. Differential bortezomib sensitivity in head and neck cancer lines corresponds to proteasome, nuclear factor-kappaB and activator protein-1 related mechanisms. Mol Cancer Ther 2008;7:1949–60. 6. Argiris A, Duffy AG, Kummar S, Simone NL, Arai Y, Kim SW, et al. Early tumor progression associated with enhanced EGFR signaling with bortezomib, cetuximab, and radiotherapy for head and neck cancer. Clin Cancer Res 2011;17:5755–64. 7. Piperdi B, Ling Y-H, Liebes L, Muggia F, Perez-Soler R. Bortezomib: understanding the mechanism of action. Mol Cancer Ther 2011;10: 2029–30. 8. Van Waes C. Targeting NF-kB in mouse models of lung adenocarcinoma. Cancer Discov 2011;1:200–2. 9. Kuhn DJ, Orlowski RZ. The immunoproteasome as a target in hematologic malignancies. Semin Hematol 2012;49:258–62. 10. Driscoll JJ, Woodle ES. Targeting the ubiquitin þ proteasome system in solid tumors. Semin Hematol 2012;49:277–83.
Clin Cancer Res; 21(5) March 1, 2015
Downloaded from clincancerres.aacrjournals.org on May 10, 2015. © 2015 American Association for Cancer Research.
943
CCR 20th Anniversary Commentary: Preclinical Study of Proteasome Inhibitor Bortezomib in Head and Neck Cancer Clint T. Allen, Barbara Conley, John B. Sunwoo, et al. Clin Cancer Res 2015;21:942-943.
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In a study published in the May 1, 2001, issue of Clinical Cancer Research, Sunwoo and colleagues provided evidence for proteasome inhibition of NF-kB and tumorigenesis, supporting early-phase clinical trials in solid malignancies of the upper aerodigestive tract. Subsequent clinical studies
uncovered a dichotomy of responses in patients with hematopoietic and solid malignancies, and the mechanisms of resistance. Clin Cancer Res; 21(5); 942–3. 2015 AACR. See related article by Sunwoo et al., Clin Cancer Res 2001;7(5) May 2001;1419–28
The transcription factor NF-kB serves as a central mediator of inflammatory and immune processes and is constitutively activated in many solid and hematopoietic malignancies. Although gain- or loss-of-function mutations directly leading to NF-kB activation are rare, genetic alterations of upstream signal and receptor kinases and extracellular signals from a proinflammatory tumor microenvironment can contribute to constitutive NF-kB activity (1). Activation of canonical and noncanonical NF-kB transcriptional activity relies upon proteasome-mediated degradation of ubiquinated cytoplasmic inhibitor-kB, which sequesters NF-kB into the cytoplasm and away from the nucleus. In response to different upstream stimuli, inhibitor-kB kinases phosphorylate inhibitor-kB, leading to its ubiquitination and degradation by the proteasome, freeing NF-kB to translocate into the nucleus. Introduction of a mutant dominant-negative inhibitor-kB abolishes measureable NF-kB activity in malignant cells, supporting the critical role of the proteasome in the regulation of NF-kB activation. Previous preclinical work demonstrating a role for NF-kB in the initiation and progression of head and neck squamous cell carcinomas (HNSCC), a group of highly inflammatory and aggressive malignancies of the upper aerodigestive tract, provided a rationale for investigating different approaches to proteasome inhibition in this disease. The work by Sunwoo and colleagues (2) established the ability of bortezomib (formerly known as PS-341), a first-inclass small-molecule inhibitor of 20S proteasome activity, to achieve significant antitumor effects in both murine and human cell models of HNSCC. This article mechanistically demonstrated reduced tumor cell viability and reduction of primary tumor
growth in both syngeneic and xenograft models via dose-dependent bortezomib inhibition of NF-kB DNA binding and target gene transactivation. This article was groundbreaking for several reasons. Not only did it build upon growing evidence implicating the central role played by NF-kB in the tumorigenesis and progression of HNSCC, it also served as an early example of the ability to use small-molecule inhibitors to specifically alter or block the activity of rationally selected targets that mediate the growth and survival of HNSCC cells. From this and other work demonstrating that NF-kB inhibition resulted in the sensitization of HNSCC cells to TNFa and radiotherapy-induced cell death, a phase I clinical trial combining escalating doses of twice-weekly bortezomib and reirradiation in patients with recurrent HNSCC was pursued (3). This trial revealed transient tumor regression or stable disease in a subset of patients, and despite being unable to administer doses tolerated by patients with multiple myeloma, provided evidence of proteasome inhibition along with altered expression of NF-kB target genes in evaluable tumor biopsies. Although these findings were encouraging, the lack of durable clinical responses despite molecular evidence of on-target bortezomib activity suggested the presence of resistance mechanisms. To better define these mechanisms of therapeutic escape, further study of clinical trial tissue samples revealed inhibition of the canonical NF-kB subunit RelA, but not noncanonical subunits RelB and cRel or components of the MAPK or STAT3 pathways following bortezomib treatment (4). These clinical data were supported by preclinical work published the same year demonstrating enhanced cytotoxicity in an HNSCC cell line relatively resistant to NF-kB inhibition alone with the addition of MAPK pathway blockade (5). Together, these data provided early evidence in HNSCC of targeted therapeutic resistance due to lack of inhibition of coactivated progrowth and prosurvival signaling pathways, a phenomenon now well recognized as a common mechanism of resistance to single-modality targeted therapy in solid tumors. Exploration of upstream genetic alterations or microenvironmental factors leading to the coactivation of NF-kB, MAPK, and STAT3 pathways led many researchers to investigate the potential role of cell surface kinase receptors such as the EGFR. Given existing preclinical and clinical evidence suggesting an additive
1 Head and Neck Surgery Branch, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, Maryland. 2Cancer Diagnosis Program, National Cancer Institute, NIH, Bethesda, Maryland. 3Division of Head and Neck Surgery, Department of Otolaryngology, Stanford University School of Medicine, Stanford, California.
Corresponding Author: Carter Van Waes, NIDCD, NIH, CRC-4732, 10 Center Drive, Bethesda, MD 20892. Phone: 301-402-4216; Fax: 301-402-1140; E-mail: [email protected] doi: 10.1158/1078-0432.CCR-14-2550 2015 American Association for Cancer Research.
942 Clin Cancer Res; 21(5) March 1, 2015
Downloaded from clincancerres.aacrjournals.org on May 10, 2015. © 2015 American Association for Cancer Research.
CCR 20th Anniversary Commentary or synergistic cytotoxic effect with the combination of NF-kB and EGFR targeted therapies, a phase I trial combining bortezomib, the anti-EGFR monoclonal antibody cetuximab, and radiation in patients with previously untreated, advanced-stage HNSCC was initiated (6). However, this clinical trial was halted before accrual was completed because of an unexpectedly high rate of early disease progression in these patients. Molecular evidence from patient tumor biopsies revealed enhanced activation of NF-kB and MAPK pathway elements downstream of EGFR, potentially due to antagonism of radiation-induced EGFR degradation following proteasome inhibition. Given that in vitro and in vivo murine models can be powerful screening tools for different therapies, this result highlights the caution that must be used when extrapolating information gleaned from preclinical work into the rational design of human clinical trials. Evaluation of bortezomib in patients with non–small cell lung cancer (NSCLC) has shown similar mixed results. Several early phase I and II trials combining bortezomib with standard chemotherapeutic or kinase receptor–targeted therapies failed to demonstrate improved disease control or survival (7). In addition, more recent work has demonstrated that initial sensitivity of RAS- and p53-mutant NSCLC cells to bortezomib-induced NF-kB inhibition was subsequently lost due to the development of NFkB–independent resistance mechanisms in vivo (8). Similar to what has been observed in HNSCC, these reports establish a consistent trend of acquired therapeutic resistance to proteasome inhibition alone through unaltered signaling of coactivated progrowth and prosurvival signaling pathways. The story of limited activity of bortezomib monotherapy in the treatment of solid tumors contrasts with the remarkable success bortezomib has shown in the treatment of hematologic malignancies. Given the known role of NF-kB in immune signaling, bortezomib was evaluated early by others as a therapy for different forms of leukemia and lymphoma, and these studies demonstrated constitutive NF-kB activation. Following large, multicenter advanced-phase clinical trials demonstrating improved outcomes compared with existing standard therapies, bortezomib, marketed as Velcade (Millennium), was FDA approved as secondline therapy for refractory mantle cell lymphoma and as first-line therapy for multiple myeloma in 2006 and 2008, respectively (9). Similarly, carflizomib, marketed as Kyprolis (Onyx), was FDA approved in 2012 for the treatment of multiple myeloma that has not shown a response to at least two prior therapies after
demonstrating significant single-agent activity in clinical trials. Mechanistically, the differential success of bortezomib in treating these malignancies may lie, in part, in its ability to effectively modulate the bcl-2 family of apoptosis-regulating proteins, known to be critical for transformed leukocyte proliferation and survival (7). Beginning with the article by Sunwoo and colleagues (2) in 2001 and in work from others, the story of bortezomib in solid and hematologic malignancies has taken divergent courses. Although bortezomib alone demonstrates significant singleagent activity in some hematopoietic cancers, the development of therapeutic resistance due to unaltered signaling through coactivated signaling pathways observed following single-agent bortezomib treatment in solid tumors has mirrored observations made with many different targeted therapies. Nevertheless, this work investigating novel combinations of existing targeted therapies, including bortezomib, holds promise. Enhanced recognition of the ability of bortezomib and its newer analogues to induce altered protein folding responses, and endoplasmic reticulum stress, with subsequent enhancement of tumor cell antigenicity, places proteasome inhibitors in an ideal position to be combined with immunotherapies (10). However, more investigation is needed, given the potential immunosuppressive effects proteasome inhibition may exert on cells of adaptive immunity. Although second-generation proteasome inhibitors are FDA approved for clinical use and also being evaluated for their effectiveness in the treatment of solid tumors, bortezomib remains the subject of continued research given its remarkable clinical activity in hematopoietic malignancies, FDA approval, and encouraging preclinical data as a component of combination therapy in various solid tumor models.
Disclosure of Potential Conflicts of Interest No potential conflicts of interest were disclosed.
Authors' Contributions Conception and design: C.T. Allen, B. Conley, J.B. Sunwoo, C. Van Waes Writing, review, and/or revision of the manuscript: C.T. Allen, B. Conley, J.B. Sunwoo, C. Van Waes Received December 1, 2014; accepted December 3, 2014; published online March 2, 2015.
References 1. DiDonato JA, Mercurio F, Karin M. NF-kB and the link between inflammation and cancer. Immunol Rev 2012;246:379–400. 2. Sunwoo JB, Chen Z, Dong G, Yeh N, Crowl Bancroft C, Sausville E, et al. Novel proteasome inhibitor PS-341 inhibits activation of nuclear factor-kB, cell survival, tumor growth, and angiogenesis in squamous cell carcinoma. Clin Cancer Res 2001; 7:1419–28. 3. Van Waes C, Chang AA, Lebowitz PF, Druzgal CH, Chen Z, Sunwoo JB, et al. Inhibition of nuclear factor-kappaB and target genes during combined therapy with proteasome inhibitor bortezomib and reirradiation in patients with recurrent head-and-neck squamous cell carcinoma. Int J Radiat Oncol Biol Phys 2005;63:1400–12. 4. Allen C, Saigal K, Nottingham L, Arun P, Chen Z, Van Waes C. Bortezomib-induced apoptosis with limited clinical response is accompanied by inhibition of canonical but not alternative nuclear factor{kappa}B subunits in head and neck cancer. Clin Cancer Res 2008; 14:4175–85.
www.aacrjournals.org
5. Chen Z, Rickler JL, Malhotra PS, Nottingham L, Bagain L, Lee TL, et al. Differential bortezomib sensitivity in head and neck cancer lines corresponds to proteasome, nuclear factor-kappaB and activator protein-1 related mechanisms. Mol Cancer Ther 2008;7:1949–60. 6. Argiris A, Duffy AG, Kummar S, Simone NL, Arai Y, Kim SW, et al. Early tumor progression associated with enhanced EGFR signaling with bortezomib, cetuximab, and radiotherapy for head and neck cancer. Clin Cancer Res 2011;17:5755–64. 7. Piperdi B, Ling Y-H, Liebes L, Muggia F, Perez-Soler R. Bortezomib: understanding the mechanism of action. Mol Cancer Ther 2011;10: 2029–30. 8. Van Waes C. Targeting NF-kB in mouse models of lung adenocarcinoma. Cancer Discov 2011;1:200–2. 9. Kuhn DJ, Orlowski RZ. The immunoproteasome as a target in hematologic malignancies. Semin Hematol 2012;49:258–62. 10. Driscoll JJ, Woodle ES. Targeting the ubiquitin þ proteasome system in solid tumors. Semin Hematol 2012;49:277–83.
Clin Cancer Res; 21(5) March 1, 2015
Downloaded from clincancerres.aacrjournals.org on May 10, 2015. © 2015 American Association for Cancer Research.
943
CCR 20th Anniversary Commentary: Preclinical Study of Proteasome Inhibitor Bortezomib in Head and Neck Cancer Clint T. Allen, Barbara Conley, John B. Sunwoo, et al. Clin Cancer Res 2015;21:942-943.
Updated version
Cited Articles
E-mail alerts Reprints and Subscriptions Permissions
Access the most recent version of this article at: http://clincancerres.aacrjournals.org/content/21/5/942
This article cites by 10 articles, 6 of which you can access for free at: http://clincancerres.aacrjournals.org/content/21/5/942.full.html#ref-list-1
Sign up to receive free email-alerts related to this article or journal. To order reprints of this article or to subscribe to the journal, contact the AACR Publications Department at [email protected]. To request permission to re-use all or part of this article, contact the AACR Publications Department at [email protected].
Downloaded from clincancerres.aacrjournals.org on May 10, 2015. © 2015 American Association for Cancer Research.
