- Email: [email protected]
Targeting K-Ras cancers
February 2016
phase I clinical trial of erlotinib and nivolumab in patients with EGFR mutated tumors has been completed (10). The regimen was feasible and well tolerated with promising antitumor activity. A randomized phase III trials of an EGFR-TKI versus an EGFR-TKI with an immune checkpoint inhibitor has been launched. Similar preclinical evidence supports the evaluations of ALK-TKIs plus an immune checkpoint inhibitor (8). Phase I testing has begun. Immunotherapy combinations. Optimizing the immune system to attack tumors will require exploiting its diverse components. Employing a dual immune approach with anti- PD-1 plus an anti- CTLA-4 agents has been successful in treating advanced melanoma. In lung cancer phase III trials of PD-1 and CTLA-4 inhibitors have been activated based on encouraging phase I data (12). Meanwhile, early phase trials evaluating immune checkpoint inhibitors with immune checkpoint agonists, cytokines, and vaccines are ongoing to determine the safest and most effective combinations. Overall we are optimistic that combination regimens that can harness the immune system together with tumor directed therapies will lead to improved clinical benefit. Continued pursuit of optimal combinations will however require increased insight into the complex interactions between the tumor, the immune response and pharmacological interventions.
References
1. Brahmer J, et al. Nivolumab versus Docetaxel in Advanced Squamous-Cell Non-Small-Cell Lung Cancer. N Engl J Med. 2015;373:123–135. 2. Borghaei H, et al. Nivolumab versus Doectaxel in Advanced NonSquamous Non-Small-Cell Lung Cancer. N Engl J Med. 2015;373:1627–1639. 3. Chen DS, et al. Oncology Meets Immunology: The Cancer-Immunity Cycle. Immunity. 2013;39:1–10. 4. Sharma P, et al. The Future of Immune Checkpoint Therapy. Science. 2015;348:56–61. 5. Vanneman M, et al. Combining Immunotherapy and Targeted Therapies in Cancer Treatment. Nature Reviews Cancer. 2012;12:237–251. 6. Antonia SJ, et al. Nivolumab in Combination with Platinum-based Doublet Chemotherapy in Advanced NonSmall Cell Lung Cancer. J Clin Oncol. 2014;32(suppl, abstract 8113). 7. Papadimitrakopoulou V, et al. Pembrolizumab plus Platinum Doublet Chemotherapy as Frontline Therapy for Advanced Non-Small-Cell Lung Cancer. J Clin Oncol. 2015;33(suppl, abstract 8031). 8. Liu S, et al. Safety and Efficacy of MPDL3280A (antiPDL1) in Combination with Platinum-based Doublet Chemotherapy in Patients with Advanced Non-Small Cell Lung Cancer. 2015;(suppl, abstract 8030). 9. Akbay EA, et al. Activaiton of PD-1 Pathway Contributes to Immune Escape in EGFR-Driven Lung Tumors. Cancer Discovery. 2013;3:1355–1363.
Abstracts
S9
10. Rizvi N, et al. Safety and Response with Nivolumab plus Erlotinib in Patients with Epidermal Growth Factor Receptor Mutated Advanced Lung Cancer. J Clin Oncol. 2014;(suppl, abstract 8022). 11. D’Incecco A, et al. PD-1 and PD-L1 Expression in Molecularly Selected Non-Small Cell Lung Cancer Patients. BJC. 2015;112:95–102. 12. Rizvi NA, et al: Safety and efficacy of first-line nivolumab and ipilimumab in non-small cell lung cancer. 16th World Conference on Lung Cancer. Abstract ORAL02.05. Presented September 7, 2015.
Targeting K-Ras cancers Frank McCormick, Man-Tzu Wang UCSF Helen Diller Family Comprehensive Cancer Center, San Francisco, CA Activating mutations in K-Ras occur frequently in lung adenocarcinomas, and are mutually exclusive with other mutations that activate the MAPK pathway, such as EGF-R and other receptor tyrosine kinases upstream, loss of neurofibromin, loss of Spred1 and activation of B-Raf. Neurofibromin and Spred1 form a functional complex that inactivates Ras by converting Ras.GTP to Ras.GDP. Neurofibromin has a GAP domain, and Spred1 is essential for directing neurofibromin to the plasma membrane. Binding of neurofibromin to Spred1 is regulated by phosphorylation, so that the level of neurofibromin that can inactivate Ras is a highly regulated process. While mutations in EGF-R, K-Ras, neurofibromin, Spred1, B-Raf and related genes are likely initiating driver mutations, knock-down of K-Ras in cell lines often has little effect on cell survival. This is presumed to be because feedback loops become activated upon K-Ras ablation, keeping cells viable. In contrast, ablation of K-Ras in pancreatic cancer cells leads to more profound effects on survival, for reasons that will be discussed. Cells transformed by KRAS display a stem-like phenotype. In contrast, cells transformed by H-Ras do not. This difference is not related to MAPK or PI3’ kinase activation, but is due to KRAS 4B’s’ unique ability to bind calmodulin, and so to inhibit calmodulin-dependent kinase. Low CaM kinase activity initiates a set of transcriptional programs that confer stem-ness. Binding of KRas to calmodulin is prevented by phosphorylation of KRas on serine-181, by an unknown isoform of protein kinase C. Treatment of mice with agents that activate PKC disrupts KRAS binding to calmodulin and prevents initiation and growth of tumor cells in vivo. Part of the “stem-ness” program initiated by K-Ras involves secretion of the cytokine LIF, an IL-6 family member with a unique role in maintaining stem-ness. Neutralization of LIF with a monoclonal antibody, or ablation of LIF expression using siRNA or CRISPR, reduces stem-ness
S10
and sensitizes established pancreas tumors to gemcitabine. LIF activates a unique set of downstream pathways, distinct from IL-6 and other members of this family of cytokines. This pathway may account for K-Ras’ unique ability to promote stem-ness. The existence of a new effector pathway specific for KRAS therefore offers new opportunities for therapeutic intervention.
Immunomodulatory effects of radiotherapy: Magical effects of the healing beam? Arta M. Monjazeb UC Davis Comprehensive Cancer Center, Sacramento, CA Immunotherapy is changing the management of metastatic lung cancer. Checkpoint inhibitors have demonstrated promising response in non-small cell lung cancer and are emerging as amongst the most efficacious anticancer agents ever discovered. Checkpoint inhibitors are aimed at reversing mechanisms of T-cell suppression by blocking signaling through regulatory T-cell co-receptors (e.g. CTLA-4 or PD-1) or blocking T-cell suppressive enzymes (e.g. Indolamine 2,3 Dioxgenase (IDO)). These therapies can achieve durable long-term remissions, however, most patients fail to respond, and some can experience significant immune-mediated toxicities (1-3). Combinatorial strategies employing immunotherapy and standard-of-care therapies may increase the efficacy of immunotherapy and extend its benefit to a larger proportion of patients. Little data is available on how best to achieve this goal. Radiotherapy (RT) is an ideal candidate for combinatorial immunotherapy strategies. In addition to debulking tumor and releasing tumor antigens, RT has well-established immunomodulatory effects (4). These interdependent and overlapping effects include increasing homing and effector function of tumor infiltrating lymphocytes (TILs) including T-cells (5) and natural killer (NK) cells (6), increasing the diversity of the T-cell response (7), destruction of immunosuppressive cells in the tumor microenvironment (8), induction of immunogenic cell death (9,10), increased dendritic cell (DC) trafficking and presentation of tumor antigen (11), and upregulation of immunogenic cell surface receptors (12) and stress ligands (6). Additionally our recent data demonstrate that RT can induce chemokines such as CCL3, 4, and 5 and the critical nature of these chemokines to an anti-tumor immune response and the effectiveness of checkpoint blockade immunotherapy has recently been highlighted (13). The immunomodulatory effects of radiotherapy are complex and some of these effects can be suppressive such as induction of TGF-beta (14), accumulation of immunosuppressive cells (15), upregulation of PD-L1 (16), and upregulation of IDO.
Journal of Thoracic Oncology
Vol. 11 No. 2S
Clinical reports confirm the safety and efficacy of multimodality strategies employing RT and CpG or IL-2 immunotherapy (17,18). There is also data to suggest synergy between RT and checkpoint inhibition (16,19,20). Dozens of clinical trials testing such combinatorial strategies are underway with countless others in preparation, which will together likely accrue thousands of patients. There is considerable variability in “standard-of-care” RT regimens and combinatorial strategies could employ a wide variety of dose/fractionation regimens, sequencing/timing regimens, and even RT quality (i.e. photons vs. protons). There is limited mechanistic data available to guide how to best combine these modalities (21,22). These variables can substantially alter the efficacy of combined RT + strategies. A framework for immunotherapy appropriately combining these therapies is needed and will have an immediate impact on patient care. It is possible that different immunotherapies and different tumors will behave differently in response to these RT variables. The mechanistic immune effects of RT and immunotherapy are complex. Identifying the best strategies to combine these immune effects will likely be similarly complex.
References
1. Brahmer JR, Tykodi SS, Chow LQ, et al. Safety and activity of anti-PD-L1 antibody in patients with advanced cancer. N Engl J Med. 2012;366:2455–2465. 2. Hodi FS, O’Day SJ, McDermott DF, et al. Improved survival with ipilimumab in patients with metastatic melanoma. N Engl J Med. 2010;363:711–723. 3. Topalian SL, Hodi FS, Brahmer JR, et al. Safety, activity, and immune correlates of anti-PD-1 antibody in cancer. N Engl J Med. 2012;366:2443–2454. 4. Dewan MZ, Galloway AE, Kawashima N, et al. Fractionated but not single-dose radiotherapy induces an immune-mediated abscopal effect when combined with anti-CTLA-4 antibody. Clin Cancer Res. 2009;15:5379– 5388. 5. Lugade AA, Moran JP, Gerber SA, Rose RC, Frelinger JG, Lord EM. Local radiation therapy of B16 melanoma tumors increases the generation of tumor antigen-specific effector cells that traffic to the tumor. J Immunol. 2005;174:7516–7523. 6. Ames E, Canter RJ, Grossenbacher SK, et al. Enhanced targeting of stem-like solid tumor cells with radiation and natural killer cells. Oncoimmunology. 2015;4:e1036212. 7. Twyman-Saint Victor C, Rech AJ, Maity A, et al. Radiation and dual checkpoint blockade activate non-redundant immune mechanisms in cancer. Nature. 2015;520:373–377. 8. Wu CY, Yang LH, Yang HY, et al. Enhanced cancer radiotherapy through immunosuppressive stromal cell destruction in tumors. Clin Cancer Res. 2014;20:644–657. 9. Apetoh L, Ghiringhelli F, Tesniere A, et al. Toll-like receptor 4-dependent contribution of the immune system to anticancer chemotherapy and radiotherapy. Nat Med. 2007;13:1050–1059.
phase I clinical trial of erlotinib and nivolumab in patients with EGFR mutated tumors has been completed (10). The regimen was feasible and well tolerated with promising antitumor activity. A randomized phase III trials of an EGFR-TKI versus an EGFR-TKI with an immune checkpoint inhibitor has been launched. Similar preclinical evidence supports the evaluations of ALK-TKIs plus an immune checkpoint inhibitor (8). Phase I testing has begun. Immunotherapy combinations. Optimizing the immune system to attack tumors will require exploiting its diverse components. Employing a dual immune approach with anti- PD-1 plus an anti- CTLA-4 agents has been successful in treating advanced melanoma. In lung cancer phase III trials of PD-1 and CTLA-4 inhibitors have been activated based on encouraging phase I data (12). Meanwhile, early phase trials evaluating immune checkpoint inhibitors with immune checkpoint agonists, cytokines, and vaccines are ongoing to determine the safest and most effective combinations. Overall we are optimistic that combination regimens that can harness the immune system together with tumor directed therapies will lead to improved clinical benefit. Continued pursuit of optimal combinations will however require increased insight into the complex interactions between the tumor, the immune response and pharmacological interventions.
References
1. Brahmer J, et al. Nivolumab versus Docetaxel in Advanced Squamous-Cell Non-Small-Cell Lung Cancer. N Engl J Med. 2015;373:123–135. 2. Borghaei H, et al. Nivolumab versus Doectaxel in Advanced NonSquamous Non-Small-Cell Lung Cancer. N Engl J Med. 2015;373:1627–1639. 3. Chen DS, et al. Oncology Meets Immunology: The Cancer-Immunity Cycle. Immunity. 2013;39:1–10. 4. Sharma P, et al. The Future of Immune Checkpoint Therapy. Science. 2015;348:56–61. 5. Vanneman M, et al. Combining Immunotherapy and Targeted Therapies in Cancer Treatment. Nature Reviews Cancer. 2012;12:237–251. 6. Antonia SJ, et al. Nivolumab in Combination with Platinum-based Doublet Chemotherapy in Advanced NonSmall Cell Lung Cancer. J Clin Oncol. 2014;32(suppl, abstract 8113). 7. Papadimitrakopoulou V, et al. Pembrolizumab plus Platinum Doublet Chemotherapy as Frontline Therapy for Advanced Non-Small-Cell Lung Cancer. J Clin Oncol. 2015;33(suppl, abstract 8031). 8. Liu S, et al. Safety and Efficacy of MPDL3280A (antiPDL1) in Combination with Platinum-based Doublet Chemotherapy in Patients with Advanced Non-Small Cell Lung Cancer. 2015;(suppl, abstract 8030). 9. Akbay EA, et al. Activaiton of PD-1 Pathway Contributes to Immune Escape in EGFR-Driven Lung Tumors. Cancer Discovery. 2013;3:1355–1363.
Abstracts
S9
10. Rizvi N, et al. Safety and Response with Nivolumab plus Erlotinib in Patients with Epidermal Growth Factor Receptor Mutated Advanced Lung Cancer. J Clin Oncol. 2014;(suppl, abstract 8022). 11. D’Incecco A, et al. PD-1 and PD-L1 Expression in Molecularly Selected Non-Small Cell Lung Cancer Patients. BJC. 2015;112:95–102. 12. Rizvi NA, et al: Safety and efficacy of first-line nivolumab and ipilimumab in non-small cell lung cancer. 16th World Conference on Lung Cancer. Abstract ORAL02.05. Presented September 7, 2015.
Targeting K-Ras cancers Frank McCormick, Man-Tzu Wang UCSF Helen Diller Family Comprehensive Cancer Center, San Francisco, CA Activating mutations in K-Ras occur frequently in lung adenocarcinomas, and are mutually exclusive with other mutations that activate the MAPK pathway, such as EGF-R and other receptor tyrosine kinases upstream, loss of neurofibromin, loss of Spred1 and activation of B-Raf. Neurofibromin and Spred1 form a functional complex that inactivates Ras by converting Ras.GTP to Ras.GDP. Neurofibromin has a GAP domain, and Spred1 is essential for directing neurofibromin to the plasma membrane. Binding of neurofibromin to Spred1 is regulated by phosphorylation, so that the level of neurofibromin that can inactivate Ras is a highly regulated process. While mutations in EGF-R, K-Ras, neurofibromin, Spred1, B-Raf and related genes are likely initiating driver mutations, knock-down of K-Ras in cell lines often has little effect on cell survival. This is presumed to be because feedback loops become activated upon K-Ras ablation, keeping cells viable. In contrast, ablation of K-Ras in pancreatic cancer cells leads to more profound effects on survival, for reasons that will be discussed. Cells transformed by KRAS display a stem-like phenotype. In contrast, cells transformed by H-Ras do not. This difference is not related to MAPK or PI3’ kinase activation, but is due to KRAS 4B’s’ unique ability to bind calmodulin, and so to inhibit calmodulin-dependent kinase. Low CaM kinase activity initiates a set of transcriptional programs that confer stem-ness. Binding of KRas to calmodulin is prevented by phosphorylation of KRas on serine-181, by an unknown isoform of protein kinase C. Treatment of mice with agents that activate PKC disrupts KRAS binding to calmodulin and prevents initiation and growth of tumor cells in vivo. Part of the “stem-ness” program initiated by K-Ras involves secretion of the cytokine LIF, an IL-6 family member with a unique role in maintaining stem-ness. Neutralization of LIF with a monoclonal antibody, or ablation of LIF expression using siRNA or CRISPR, reduces stem-ness
S10
and sensitizes established pancreas tumors to gemcitabine. LIF activates a unique set of downstream pathways, distinct from IL-6 and other members of this family of cytokines. This pathway may account for K-Ras’ unique ability to promote stem-ness. The existence of a new effector pathway specific for KRAS therefore offers new opportunities for therapeutic intervention.
Immunomodulatory effects of radiotherapy: Magical effects of the healing beam? Arta M. Monjazeb UC Davis Comprehensive Cancer Center, Sacramento, CA Immunotherapy is changing the management of metastatic lung cancer. Checkpoint inhibitors have demonstrated promising response in non-small cell lung cancer and are emerging as amongst the most efficacious anticancer agents ever discovered. Checkpoint inhibitors are aimed at reversing mechanisms of T-cell suppression by blocking signaling through regulatory T-cell co-receptors (e.g. CTLA-4 or PD-1) or blocking T-cell suppressive enzymes (e.g. Indolamine 2,3 Dioxgenase (IDO)). These therapies can achieve durable long-term remissions, however, most patients fail to respond, and some can experience significant immune-mediated toxicities (1-3). Combinatorial strategies employing immunotherapy and standard-of-care therapies may increase the efficacy of immunotherapy and extend its benefit to a larger proportion of patients. Little data is available on how best to achieve this goal. Radiotherapy (RT) is an ideal candidate for combinatorial immunotherapy strategies. In addition to debulking tumor and releasing tumor antigens, RT has well-established immunomodulatory effects (4). These interdependent and overlapping effects include increasing homing and effector function of tumor infiltrating lymphocytes (TILs) including T-cells (5) and natural killer (NK) cells (6), increasing the diversity of the T-cell response (7), destruction of immunosuppressive cells in the tumor microenvironment (8), induction of immunogenic cell death (9,10), increased dendritic cell (DC) trafficking and presentation of tumor antigen (11), and upregulation of immunogenic cell surface receptors (12) and stress ligands (6). Additionally our recent data demonstrate that RT can induce chemokines such as CCL3, 4, and 5 and the critical nature of these chemokines to an anti-tumor immune response and the effectiveness of checkpoint blockade immunotherapy has recently been highlighted (13). The immunomodulatory effects of radiotherapy are complex and some of these effects can be suppressive such as induction of TGF-beta (14), accumulation of immunosuppressive cells (15), upregulation of PD-L1 (16), and upregulation of IDO.
Journal of Thoracic Oncology
Vol. 11 No. 2S
Clinical reports confirm the safety and efficacy of multimodality strategies employing RT and CpG or IL-2 immunotherapy (17,18). There is also data to suggest synergy between RT and checkpoint inhibition (16,19,20). Dozens of clinical trials testing such combinatorial strategies are underway with countless others in preparation, which will together likely accrue thousands of patients. There is considerable variability in “standard-of-care” RT regimens and combinatorial strategies could employ a wide variety of dose/fractionation regimens, sequencing/timing regimens, and even RT quality (i.e. photons vs. protons). There is limited mechanistic data available to guide how to best combine these modalities (21,22). These variables can substantially alter the efficacy of combined RT + strategies. A framework for immunotherapy appropriately combining these therapies is needed and will have an immediate impact on patient care. It is possible that different immunotherapies and different tumors will behave differently in response to these RT variables. The mechanistic immune effects of RT and immunotherapy are complex. Identifying the best strategies to combine these immune effects will likely be similarly complex.
References
1. Brahmer JR, Tykodi SS, Chow LQ, et al. Safety and activity of anti-PD-L1 antibody in patients with advanced cancer. N Engl J Med. 2012;366:2455–2465. 2. Hodi FS, O’Day SJ, McDermott DF, et al. Improved survival with ipilimumab in patients with metastatic melanoma. N Engl J Med. 2010;363:711–723. 3. Topalian SL, Hodi FS, Brahmer JR, et al. Safety, activity, and immune correlates of anti-PD-1 antibody in cancer. N Engl J Med. 2012;366:2443–2454. 4. Dewan MZ, Galloway AE, Kawashima N, et al. Fractionated but not single-dose radiotherapy induces an immune-mediated abscopal effect when combined with anti-CTLA-4 antibody. Clin Cancer Res. 2009;15:5379– 5388. 5. Lugade AA, Moran JP, Gerber SA, Rose RC, Frelinger JG, Lord EM. Local radiation therapy of B16 melanoma tumors increases the generation of tumor antigen-specific effector cells that traffic to the tumor. J Immunol. 2005;174:7516–7523. 6. Ames E, Canter RJ, Grossenbacher SK, et al. Enhanced targeting of stem-like solid tumor cells with radiation and natural killer cells. Oncoimmunology. 2015;4:e1036212. 7. Twyman-Saint Victor C, Rech AJ, Maity A, et al. Radiation and dual checkpoint blockade activate non-redundant immune mechanisms in cancer. Nature. 2015;520:373–377. 8. Wu CY, Yang LH, Yang HY, et al. Enhanced cancer radiotherapy through immunosuppressive stromal cell destruction in tumors. Clin Cancer Res. 2014;20:644–657. 9. Apetoh L, Ghiringhelli F, Tesniere A, et al. Toll-like receptor 4-dependent contribution of the immune system to anticancer chemotherapy and radiotherapy. Nat Med. 2007;13:1050–1059.