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Radiation and dual checkpoint blockade activate non-redundant immune mechanisms in cancer.

Twyman-Saint Victor C, Rech AJ, Maity A, Rengan R, Pauken KE, Stelekati E, Benci JL, Xu B, Dada H, Odorizzi PM, Herati RS, Mansfield KD, Patsch D, Amaravadi RK, Schuchter LM, Ishwaran H, Mick R, Pryma DA, Xu X, Feldman MD, Gangadhar TC, Hahn SM, Wherry EJ, Vonderheide RH, Minn AJ - Nature (2015)

Bottom Line: Immune checkpoint inhibitors result in impressive clinical responses, but optimal results will require combination with each other and other therapies.Anti-CTLA4 predominantly inhibits T-regulatory cells (Treg cells), thereby increasing the CD8 T-cell to Treg (CD8/Treg) ratio.Addition of PD-L1 blockade reverses T-cell exhaustion to mitigate depression in the CD8/Treg ratio and further encourages oligoclonal T-cell expansion.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA [2] Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.

ABSTRACT
Immune checkpoint inhibitors result in impressive clinical responses, but optimal results will require combination with each other and other therapies. This raises fundamental questions about mechanisms of non-redundancy and resistance. Here we report major tumour regressions in a subset of patients with metastatic melanoma treated with an anti-CTLA4 antibody (anti-CTLA4) and radiation, and reproduced this effect in mouse models. Although combined treatment improved responses in irradiated and unirradiated tumours, resistance was common. Unbiased analyses of mice revealed that resistance was due to upregulation of PD-L1 on melanoma cells and associated with T-cell exhaustion. Accordingly, optimal response in melanoma and other cancer types requires radiation, anti-CTLA4 and anti-PD-L1/PD-1. Anti-CTLA4 predominantly inhibits T-regulatory cells (Treg cells), thereby increasing the CD8 T-cell to Treg (CD8/Treg) ratio. Radiation enhances the diversity of the T-cell receptor (TCR) repertoire of intratumoral T cells. Together, anti-CTLA4 promotes expansion of T cells, while radiation shapes the TCR repertoire of the expanded peripheral clones. Addition of PD-L1 blockade reverses T-cell exhaustion to mitigate depression in the CD8/Treg ratio and further encourages oligoclonal T-cell expansion. Similarly to results from mice, patients on our clinical trial with melanoma showing high PD-L1 did not respond to radiation plus anti-CTLA4, demonstrated persistent T-cell exhaustion, and rapidly progressed. Thus, PD-L1 on melanoma cells allows tumours to escape anti-CTLA4-based therapy, and the combination of radiation, anti-CTLA4 and anti-PD-L1 promotes response and immunity through distinct mechanisms.

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Patients and mice treated with RT + anti-CTLA4 for melanomaa) Twenty-two stage IV melanoma patients (M stage indicated) were stratified by treatment site of a single index metastasis, which was the irradiated tumor. Two dosing levels (DL) for stereotactic body radiation (SBRT) were in each stratum. b) Waterfall plot of the RECIST % change from baseline of unirradiated tumors annotated to indicate metabolic responses by PET/CT (hatches above plot) and response of the irradiated index tumor as measured by CT and PET/CT (hatches below plot). RECIST criteria do not include irradiated tumors. Legend shows color-codes for response after CT or PET/CT (parenthesis). PMD: progressive metabolic disease; SMD: stable metabolic disease; PMR: partial metabolic response; CMR: complete metabolic response. White hatches indicate no imaging obtained. See Extended Data Table 2. c) Survival (right) and total tumor growth (bottom) after RT with either concurrent or sequential anti-CTLA4 compared to anti-CTLA4 (C4) or RT alone. The regimens and the standard regimen used for all other melanoma experiments are illustrated (left). The p-values for tumor growth are compared to anti-CTLA4. d) Survival after RT and/or anti-CTLA4 with or without T cell depletion (n=5–10) using anti-CD8 (CD8). Shown are overall p-values. The p-value for RT + anti-CTLA4 with and without anti-CD8 is p=0.005. Control is an isotype-matched antibody. e) Three mice with CRs were rechallenged with B16-F10 tumors. Shown is a representative mouse. Arrow indicates location of regressed tumor and vitiligo-like condition represented by non-pigmented fur (observed in approximately 50% of mice with CRs). Time line starts from original tumor implantation (day 0) and values above marks are days after first rechallenge. Recurrence occurred only after anti-CD8 treatment and second rechallenge.
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Figure 5: Patients and mice treated with RT + anti-CTLA4 for melanomaa) Twenty-two stage IV melanoma patients (M stage indicated) were stratified by treatment site of a single index metastasis, which was the irradiated tumor. Two dosing levels (DL) for stereotactic body radiation (SBRT) were in each stratum. b) Waterfall plot of the RECIST % change from baseline of unirradiated tumors annotated to indicate metabolic responses by PET/CT (hatches above plot) and response of the irradiated index tumor as measured by CT and PET/CT (hatches below plot). RECIST criteria do not include irradiated tumors. Legend shows color-codes for response after CT or PET/CT (parenthesis). PMD: progressive metabolic disease; SMD: stable metabolic disease; PMR: partial metabolic response; CMR: complete metabolic response. White hatches indicate no imaging obtained. See Extended Data Table 2. c) Survival (right) and total tumor growth (bottom) after RT with either concurrent or sequential anti-CTLA4 compared to anti-CTLA4 (C4) or RT alone. The regimens and the standard regimen used for all other melanoma experiments are illustrated (left). The p-values for tumor growth are compared to anti-CTLA4. d) Survival after RT and/or anti-CTLA4 with or without T cell depletion (n=5–10) using anti-CD8 (CD8). Shown are overall p-values. The p-value for RT + anti-CTLA4 with and without anti-CD8 is p=0.005. Control is an isotype-matched antibody. e) Three mice with CRs were rechallenged with B16-F10 tumors. Shown is a representative mouse. Arrow indicates location of regressed tumor and vitiligo-like condition represented by non-pigmented fur (observed in approximately 50% of mice with CRs). Time line starts from original tumor implantation (day 0) and values above marks are days after first rechallenge. Recurrence occurred only after anti-CD8 treatment and second rechallenge.

Mentions: Anecdotal clinical reports suggest that RT may cooperate with anti-CTLA4 to systemically enhance melanoma response7; however, this combination has not been reported in a clinical trial. To examine the feasibility and efficacy of RT combined with immune checkpoint blockade, we initiated a phase I clinical trial of 22 patients with multiple melanoma metastases (Extended Data Table 1). A single index lesion was irradiated with hypofractionated RT, delivered over two or three fractions, followed by four cycles of the anti-CTLA4 antibody ipilimumab (Extended Data Fig. 1a). Accrual was completed in three out of four RT dose levels, and treatment was well tolerated (Extended Data Table 2). Evaluation of the unirradiated lesions by CT imaging using Response Evaluation Criteria in Solid Tumors (RECIST) demonstrated that 18% of patients had a partial response (PR) as best response, 18% had stable disease (SD), and 64% had progressive disease (PD) (Fig. 1a). For example, patient PT-402 showed a large reduction in sizes of unirradiated tumors and a partial metabolic response by positron emission tomography (PET) (Fig. 1b). None of the 12 patients evaluated by PET had progressive metabolic disease in the irradiated lesion (Extended Data Fig. 1b, Extended Data Table 3). The median progression-free survival (PFS) and overall survival (OS) was 3.8 and 10.7 months with median follow-up of 18.4 and 21.3 months (18.0 and 21.3 for patients without event), respectively (Fig. 1c).


Radiation and dual checkpoint blockade activate non-redundant immune mechanisms in cancer.

Twyman-Saint Victor C, Rech AJ, Maity A, Rengan R, Pauken KE, Stelekati E, Benci JL, Xu B, Dada H, Odorizzi PM, Herati RS, Mansfield KD, Patsch D, Amaravadi RK, Schuchter LM, Ishwaran H, Mick R, Pryma DA, Xu X, Feldman MD, Gangadhar TC, Hahn SM, Wherry EJ, Vonderheide RH, Minn AJ - Nature (2015)

Patients and mice treated with RT + anti-CTLA4 for melanomaa) Twenty-two stage IV melanoma patients (M stage indicated) were stratified by treatment site of a single index metastasis, which was the irradiated tumor. Two dosing levels (DL) for stereotactic body radiation (SBRT) were in each stratum. b) Waterfall plot of the RECIST % change from baseline of unirradiated tumors annotated to indicate metabolic responses by PET/CT (hatches above plot) and response of the irradiated index tumor as measured by CT and PET/CT (hatches below plot). RECIST criteria do not include irradiated tumors. Legend shows color-codes for response after CT or PET/CT (parenthesis). PMD: progressive metabolic disease; SMD: stable metabolic disease; PMR: partial metabolic response; CMR: complete metabolic response. White hatches indicate no imaging obtained. See Extended Data Table 2. c) Survival (right) and total tumor growth (bottom) after RT with either concurrent or sequential anti-CTLA4 compared to anti-CTLA4 (C4) or RT alone. The regimens and the standard regimen used for all other melanoma experiments are illustrated (left). The p-values for tumor growth are compared to anti-CTLA4. d) Survival after RT and/or anti-CTLA4 with or without T cell depletion (n=5–10) using anti-CD8 (CD8). Shown are overall p-values. The p-value for RT + anti-CTLA4 with and without anti-CD8 is p=0.005. Control is an isotype-matched antibody. e) Three mice with CRs were rechallenged with B16-F10 tumors. Shown is a representative mouse. Arrow indicates location of regressed tumor and vitiligo-like condition represented by non-pigmented fur (observed in approximately 50% of mice with CRs). Time line starts from original tumor implantation (day 0) and values above marks are days after first rechallenge. Recurrence occurred only after anti-CD8 treatment and second rechallenge.
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Related In: Results  -  Collection

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Figure 5: Patients and mice treated with RT + anti-CTLA4 for melanomaa) Twenty-two stage IV melanoma patients (M stage indicated) were stratified by treatment site of a single index metastasis, which was the irradiated tumor. Two dosing levels (DL) for stereotactic body radiation (SBRT) were in each stratum. b) Waterfall plot of the RECIST % change from baseline of unirradiated tumors annotated to indicate metabolic responses by PET/CT (hatches above plot) and response of the irradiated index tumor as measured by CT and PET/CT (hatches below plot). RECIST criteria do not include irradiated tumors. Legend shows color-codes for response after CT or PET/CT (parenthesis). PMD: progressive metabolic disease; SMD: stable metabolic disease; PMR: partial metabolic response; CMR: complete metabolic response. White hatches indicate no imaging obtained. See Extended Data Table 2. c) Survival (right) and total tumor growth (bottom) after RT with either concurrent or sequential anti-CTLA4 compared to anti-CTLA4 (C4) or RT alone. The regimens and the standard regimen used for all other melanoma experiments are illustrated (left). The p-values for tumor growth are compared to anti-CTLA4. d) Survival after RT and/or anti-CTLA4 with or without T cell depletion (n=5–10) using anti-CD8 (CD8). Shown are overall p-values. The p-value for RT + anti-CTLA4 with and without anti-CD8 is p=0.005. Control is an isotype-matched antibody. e) Three mice with CRs were rechallenged with B16-F10 tumors. Shown is a representative mouse. Arrow indicates location of regressed tumor and vitiligo-like condition represented by non-pigmented fur (observed in approximately 50% of mice with CRs). Time line starts from original tumor implantation (day 0) and values above marks are days after first rechallenge. Recurrence occurred only after anti-CD8 treatment and second rechallenge.
Mentions: Anecdotal clinical reports suggest that RT may cooperate with anti-CTLA4 to systemically enhance melanoma response7; however, this combination has not been reported in a clinical trial. To examine the feasibility and efficacy of RT combined with immune checkpoint blockade, we initiated a phase I clinical trial of 22 patients with multiple melanoma metastases (Extended Data Table 1). A single index lesion was irradiated with hypofractionated RT, delivered over two or three fractions, followed by four cycles of the anti-CTLA4 antibody ipilimumab (Extended Data Fig. 1a). Accrual was completed in three out of four RT dose levels, and treatment was well tolerated (Extended Data Table 2). Evaluation of the unirradiated lesions by CT imaging using Response Evaluation Criteria in Solid Tumors (RECIST) demonstrated that 18% of patients had a partial response (PR) as best response, 18% had stable disease (SD), and 64% had progressive disease (PD) (Fig. 1a). For example, patient PT-402 showed a large reduction in sizes of unirradiated tumors and a partial metabolic response by positron emission tomography (PET) (Fig. 1b). None of the 12 patients evaluated by PET had progressive metabolic disease in the irradiated lesion (Extended Data Fig. 1b, Extended Data Table 3). The median progression-free survival (PFS) and overall survival (OS) was 3.8 and 10.7 months with median follow-up of 18.4 and 21.3 months (18.0 and 21.3 for patients without event), respectively (Fig. 1c).

Bottom Line: Immune checkpoint inhibitors result in impressive clinical responses, but optimal results will require combination with each other and other therapies.Anti-CTLA4 predominantly inhibits T-regulatory cells (Treg cells), thereby increasing the CD8 T-cell to Treg (CD8/Treg) ratio.Addition of PD-L1 blockade reverses T-cell exhaustion to mitigate depression in the CD8/Treg ratio and further encourages oligoclonal T-cell expansion.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA [2] Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.

ABSTRACT
Immune checkpoint inhibitors result in impressive clinical responses, but optimal results will require combination with each other and other therapies. This raises fundamental questions about mechanisms of non-redundancy and resistance. Here we report major tumour regressions in a subset of patients with metastatic melanoma treated with an anti-CTLA4 antibody (anti-CTLA4) and radiation, and reproduced this effect in mouse models. Although combined treatment improved responses in irradiated and unirradiated tumours, resistance was common. Unbiased analyses of mice revealed that resistance was due to upregulation of PD-L1 on melanoma cells and associated with T-cell exhaustion. Accordingly, optimal response in melanoma and other cancer types requires radiation, anti-CTLA4 and anti-PD-L1/PD-1. Anti-CTLA4 predominantly inhibits T-regulatory cells (Treg cells), thereby increasing the CD8 T-cell to Treg (CD8/Treg) ratio. Radiation enhances the diversity of the T-cell receptor (TCR) repertoire of intratumoral T cells. Together, anti-CTLA4 promotes expansion of T cells, while radiation shapes the TCR repertoire of the expanded peripheral clones. Addition of PD-L1 blockade reverses T-cell exhaustion to mitigate depression in the CD8/Treg ratio and further encourages oligoclonal T-cell expansion. Similarly to results from mice, patients on our clinical trial with melanoma showing high PD-L1 did not respond to radiation plus anti-CTLA4, demonstrated persistent T-cell exhaustion, and rapidly progressed. Thus, PD-L1 on melanoma cells allows tumours to escape anti-CTLA4-based therapy, and the combination of radiation, anti-CTLA4 and anti-PD-L1 promotes response and immunity through distinct mechanisms.

Show MeSH
Related in: MedlinePlus