Outcomes In Metastatic Melanoma Patients Research Articles

20. MELANOMA CELL INTRINSIC GABAA RECEPTOR ENHANCEMENT POTENTIATES RADIATION AND IMMUNE CHECKPOINT INHIBITOR RESPONSE BY PROMOTING DIRECT AND T CELL-MEDIATED ANTI-TUMOR ACTIVITY

Most metastatic melanoma patients exhibit poor and variable response to radiotherapy and targeted therapies, including immune checkpoint inhibitors. There is a need for therapeutics that can potentiate existing treatments to positively impact clinical outcomes of metastatic melanoma patients. We reanalyzed melanoma TCGA transcriptomes and identified, as linked to previously defined molecular subgroups, enhanced expression of genes coding for subunits of the Type A GABA receptor (GABAAR), a chloride ion channel and major inhibitory neurotransmitter receptor. Using whole-cell patch clamp electrophysiology, we find that melanoma cells possess GABAARs that control membrane permeability to anions. Select benzodiazepines, by enhancing GABAAR mediated anion transport, depolarize melanoma cell mitochondrial membrane potential and impair cell viability in vitro. Using a syngeneic melanoma mouse model, we find that a benzodiazepine promotes reduction in tumor volume when administered alone and potentiated radiation or immune checkpoint inhibitor α-PD-L1. When a benzodiazepine is combined with concurrent α-PD-L1 and a sub-lethal radiation dose, there is near complete loss of tumor, beyond what is observed for benzodiazepine with radiation or α-PD-L1. Mechanistically, benzodiazepine with radiation or α-PD-L1 results in ipsilateral and an abscopal tumor volume reduction commensurate with enhanced infiltration into the tumor milieu of polyfunctional CD8 T-cells. There is also an increased expression of genes with roles in the cytokine-cytokine receptor and p53 signaling pathways. This study provides evidence for melanoma cell GABAARs as a therapeutic vulnerability with benzodiazepines promoting both direct and immune-mediated anti-tumor activity.

The Association of Radiation Dose-Fractionation and Immunotherapy Use With Overall Survival in Metastatic Melanoma Patients

ObjectiveMetastatic melanoma patients often receive palliative radiotherapy (RT) and immunotherapy (IT). However, the immunological interplay between RT dose-fractionation and IT is uncertain, and the optimal treatment strategy using RT and IT in metastatic melanoma remains unclear. Our main objective was to examine the effect of RT dose-fractionation on overall survival (OS).MethodsUsing the National Cancer Database (NCDB), we classified metastatic melanoma patients who received palliative RT into two dose-fractionation groups - conventionally fractionated RT (CFRT; <5 Gy/fraction) and hypofractionated RT (HFRT: ≥5 Gy/fraction) - with or without IT. Survival analysis was performed using the Cox regression model, Kaplan-Meier method, and propensity-score matching (PSM).ResultsA total of 5,281 metastatic melanoma patients were included, with a median follow-up of 5.9 months. The three-year OS was highest in patients who received HFRT+IT [37.3% (95% CI: 31.1-43.5)] compared to those who received HFRT alone [19.0% (95% CI: 16.2-21.9)], CFRT+IT [17.6 (95%CI: 13.9-21.6)], or CFRT alone [8.6% (95%CI: 7.6-9.7); p<0.0001]. The magnitude of OS benefit with the use of IT was greater in those who received HFRT (18.3%) compared with those who received CFRT (9.0%) (p<0.0001). The addition of IT to HFRT, compared to CFRT, was associated with greater OS benefit in patients treated with RT to the brain and soft tissue/visceral (STV) sites. On PSM analysis, HFRT+IT was associated with improved three-year OS compared to other treatments.ConclusionMetastatic melanoma patients who received HFRT+IT was associated with the greatest OS benefit. Our findings warrant further prospective evaluation as to whether higher RT dose-per-fraction improves clinical outcomes in metastatic melanoma patients receiving IT.

Clinical value of noninvasive biomarkers reflecting a collagen-rich stroma in metastatic melanoma patients treated with anti-PD1 therapy.

3049 Background: Poor response to anti-PD1/PD-L1 remains a clinical challenge in a subgroup of patients with metastatic melanoma. Recent evidence strongly suggests that these poor responses are associated with TGF-β signaling and CD8+ T-cell excluded tumors characterized by a collagen-rich peritumoral stroma that blocks the interaction between T cells and tumor cells. In the pursuit of identifying non-invasive biomarkers associated with a T-cell excluded phenotype and predict resistance/response to immune checkpoint inhibitor therapy, we evaluated the association between blood-based biomarkers measuring type III collagen formation and cross-linking and survival outcomes in metastatic melanoma patients treated with anti-PD1 therapy. Methods: 107 patients with metastatic melanoma who started anti-PD1 monotherapy between May 2016 – March 2019 entered in a prospective real-life study (nivolumab n = 62, pembrolizumab n = 45). Type III collagen formation (PRO-C3) and type III collagen formation and cross-linking (PC3X) were measured with ELISAs in pre-treatment serum. Biomarker levels were associated to Disease Control Rate (according to RECIST v.1.1) by Mann-Whitney test and correlated to survival outcomes by Kaplan-Meier and Cox regression analyses. Results: PRO-C3 was significantly elevated in patients with progressive disease compared to the combined group of patients with complete response, partial response and stable disease (p = 0.046). High PRO-C3 and PC3X ( &gt; 75th percentile) prior to treatment were significantly associated with poor overall survival (PRO-C3: HR = 2.4, p = 0.008; PC3X: HR = 2.2, p = 0.019) and progression free survival (PRO-C3: HR = 1.91, p = 0.016; PC3X: HR = 1.94, p = 0.013). The median overall survival was 417 and 511 days in biomarker high patients compared to 1269 and 1269 days in biomarker low patients, for PRO-C3 and PC3X, respectively. Conclusions: Biomarkers quantified in a pre-treatment liquid biopsy reflecting excessive collagen formation and cross-linking were associated with poor response and survival outcomes in metastatic melanoma patients treated with anti-PD1 therapy. This supports an association between collagen formation and resistance to anti-PD1 therapy. Furthermore, if validated, these non-invasive collagen biomarkers may have potential for guiding patient stratification for immune checkpoint inhibitor therapy and combination therapies. Clinical trial information: NTR7015 .

Chemo-immunotherapy combination after PD-1 inhibitor failure improves clinical outcomes in metastatic melanoma patients.

Management of PD-1 blockade resistance in metastatic melanoma (MM) remains challenging. Immunotherapy or chemotherapy alone provides limited benefit in this setting. Chemo-immunotherapy (CIT) has demonstrated favorable efficacy and safety profiles in lung cancer. Our pre-clinical study showed that in MM patients who have failed PD-1 blockade, the addition of chemotherapy increases CX3CR1+ therapy-responsive CD8+ T-cells with enhanced anti-tumor activity, resulting in improved clinical response. Here, we examined the clinical outcomes of CIT in MM patients after PD-1 blockade failure and the treatment-related changes in CX3CR1+ therapy-responsive CD8+ T-cells. We reviewed MM patients seen between January 2012 and June 2018 who failed anti-PD-1-based therapy and received subsequent CIT, immune checkpoint inhibitors (ICI) or chemotherapy alone. Overall survival (OS), objective response rate (ORR), event-free survival (EFS), and toxicities were assessed. Among 60 patients, 33 received CIT upon disease progression on PD-1 blockade. At a median follow-up of 3.9 years, the CIT group had a median OS of 3.5 years [95% confidence interval (CI) 1.7-NR] vs. 1.8 years (95% CI 0.9-2; P = 0.002) for those who received subsequent ICI (n = 9) or chemotherapy alone (n = 18), with ORR of 59% vs. 15% (P = 0.0003), respectively. The median EFS was 7.6 months (95% CI 6-10) following CIT vs. 3.4 months (95% CI 2.8-4.1; P = 0.0005) following ICI or chemotherapy alone. Therapy-responsive CX3CR1+CD8+ T-cells showed dynamic increase with successful CIT. CIT showed favorable clinical outcomes and acceptable safety profile in PD-1 blockade-resistant patients. CX3CR1+CD8+ therapy-responsive T-cells can be potentially used for monitoring disease response to CIT.

1316PD - Plasma proteomics in patients with metastatic cutaneous melanoma treated with immune checkpoint inhibitors

BackgroundThe introduction of immune checkpoint inhibitors (ICIs) or therapies targeting the MAPK-pathway (MAPKis) has significantly improved clinical outcomes in metastatic melanoma patients. Till, a large proportion of the patients become resistant to therapy and there is a need for treatment predictive biomarkers. The aim of this study was to analyze the treatment predictive biomarkers based on the plasma proteome of patients with metastatic melanoma treated with ICIs. MethodsWe analyzed serial plasma samples from 48 patients with metastatic melanoma collected; 24 patients were treated with ICIs and with MAPKis as a control group. A non-biased, high-resolution isoelectric focusing of peptides-liquid chromatography-mass spectrometry (HiRIEFLC-MS/MS)-based method, and with proximity ligation assays (PEA) targeting 92 immuno-oncology-related proteins were used. We analyzed the change in protein levels during treatment with a paired t-test, and their association with progression free survival (PFS) with Cox proportional hazards models. ResultsHiRIEFLC-MS/MS detected 1,835 proteins. We detected statistically-significant log2-fold-changes in 109 protein levels out of 1,160 proteins tested (not corrected for multiple testing). PDCD-1 had the highest log2-fold change (FC=1.27) after treatment (p=0.02). After stratifying for treatment type, PDCD-1 levels increased in patients treated with ICIs (FC=2.13, p=0.0008), but not in MAPKis-treated patients. PEA analyses confirmed this observation. The PEA panel showed association between 44 proteins and shorter PFS (pcoefficient <0.05, pLRT<0.05, qLRT<0.05), among them: LGALS1, CSF1, VEGFA, CASP8, CCL2, TNFSF14, ANGPT2, IL10, IL6, and ADGRG1. Of these, increase in plasma levels during treatment of LGALS1, CCL2 and ADGRG1 were associated with longer PFS. HiRIEF LC-MS/MS detected 69 proteins associated with PFS (pcoefficient< 0.05, pLRT< 0.05, qLRT < 0.05). ConclusionsBy using HiRIEFLC-MS/MS, we could detect putative treatment predictive proteins in plasma from patients with metastatic melanoma treated with ICIs. Our findings require further validation. Legal entity responsible for the studyThe authors. FundingThe Swedish Cancer Society, The Radiumhemmet research funds, the Swedish Medical Society of Research, The Swedish Medical Society, Waldenström fund. DisclosureAll authors have declared no conflicts of interest.

Undetectable circulating tumor DNA (ctDNA) levels correlate with favorable outcome in metastatic melanoma patients treated with anti-PD1 therapy

BackgroundTreatment with anti-PD1 monoclonal antibodies improves the survival of metastatic melanoma patients but only a subgroup of patients benefits from durable disease control. Predictive biomarkers for durable benefit could improve the clinical management of patients.MethodsPlasma samples were collected from patients receiving anti-PD1 therapy for ctDNA quantitative assessment of BRAFV600 and NRASQ61/G12/G13 mutations.ResultsAfter a median follow-up of 84 weeks 457 samples from 85 patients were analyzed. Patients with undetectable ctDNA at baseline had a better PFS (Hazard ratio (HR) = 0.47, median 26 weeks versus 9 weeks, p = 0.01) and OS (HR = 0.37, median not reached versus 21.3 weeks, p = 0.005) than patients with detectable ctDNA. Additionally, the HR for death was lower after the ctDNA level became undetectable during follow-up (adjusted HR: 0.16 (95% CI 0.07–0.36), p-value < 0.001). ctDNA levels > 500 copies/ml at baseline or week 3 were associated with poor clinical outcome. Patients progressive exclusively in the central nervous system (CNS) had undetectable ctDNA at baseline and at subsequent assessments. In multivariate analysis adjusted for LDH, CRP, ECOG and number of metastatic sites, the ctDNA remained significant for PFS and OS. A positive correlation was observed between ctDNA levels and total metabolic tumor volume (TMTV), number of metastatic sites and total tumor burden.ConclusionsAssessment of ctDNA baseline and during therapy was predictive for tumor response and clinical outcome in metastatic melanoma patients and reflected the tumor burden. ctDNA evaluation provided reliable complementary information during anti-PD1 antibody therapy.

Plasma proteomic analyses and treatment predictive biomarker candidates in melanoma patients receiving immune checkpoint blockade or targeted therapy.

9574 Background: The introduction of immune checkpoint inhibitors (ICIs) or therapies targeting the MAPK-pathway (MAPKis) has significantly improved clinical outcomes in metastatic melanoma patients. Still, a large proportion of the patients become resistant to therapy and there is a need for treatment predictive biomarkers. The aim of this study was to analyze the treatment predictive biomarkers based on the plasma proteome of patients with metastatic melanoma treated with ICIs or MAPKis. Methods: We analyzed serial plasma samples from 48 patients with metastatic melanoma collected; 24 patients were treated with ICIs and with MAPKis, respcetively. A non-biased, high-resolution isoelectric focusing of peptides-liquid chromatography-mass spectrometry (HiRIEFLC-MS/MS)-based method, and with proximity ligation assays (PEA) targeting 92 immuno-oncology-related proteins were used.We analyzed the change in protein levels during treatment with a paired t-test, and their association with progression free survival (PFS) with Cox proportional hazards models. Results: HiRIEFLC-MS/MS detected 1,835 proteins.We detected statistically-significant log2-fold-changes in 109 protein levels out of 1,160 proteins tested (not corrected for multiple testing). PDCD-1 had the highest log2-fold change (FC = 1.27) after treatment (p = 0.02). After stratifying for treatment type, PDCD-1 levels increased in patients treated with ICIs (FC = 2.13, p= 0.0008), but not in MAPKis-treated patients. PEA analyses confirmed this observation. The PEA panel showed association between 44 proteins and shorter PFS (pcoefficient &lt;0.05, pLRT&lt;0.05, qLRT&lt;0.05), among them: LGALS1, CSF1, VEGFA, CASP8, CCL2, TNFSF14, ANGPT2, IL10, IL6, and ADGRG1. Of these, increase in plasma levels during treatment of LGALS1, CCL2 and ADGRG1 were associated with longer PFS. HiRIEF LC-MS/MS detected 69 proteins associated with PFS (pcoefficient&lt; 0.05, pLRT&lt; 0.05, qLRT &lt; 0.05). Conclusions: By using HiRIEFLC-MS/MS, we could detect putative treatment predictive proteins in plasma from patients with metastatic melanoma treated with ICIs or MAPKis. Our findings require further validation.

Chemo-immunotherapy combination after PD-1 inhibitor failure improves clinical outcomes in metastatic melanoma patients.

138 Background: Clinical management of metastatic melanoma (MM) after PD-1 blockade failure remains challenging and lacks a standard of care. Chemo-immunotherapy (CIT) combinations have demonstrated favorable efficacy and safety profiles in lung cancer patients. In this study, we compared the clinical outcomes of CIT with immunotherapy or chemotherapy alone after PD-1 blockade failure. Methods: We reviewed MM patients seen at Mayo Clinic between Jan, 2012 and Jun, 2018 who failed anti-PD1 therapy and received subsequent CIT, or immune checkpoint inhibitors (ICI) or chemotherapy alone. A total of 60 patients were analyzed, the CIT cohort [n=33 (55%)] treatment consisted of carboplatin/paclitaxel (n=29), nab-paclitaxel (n=2), paclitaxel (n=1), and temozolomide (n=1). In the ICI (n=9) or chemotherapy alone cohort (n=18) [n=27 (45%)], treatment consisted of carboplatin/paclitaxel (n=11), temozolomide (n=4), nab-paclitaxel (n=3), ipilimumab/nivolumab (n=4), pembrolizumab (n=4), or nivolumab (n=1). Results: Patients in the CIT cohort had a median OS of 3.5 years (95% CI: 1.7-NR) compared to 1.8 years (95% CI: 0.9-2) in the ICI or chemotherapy alone cohort, p=0.02. The median EFS following CIT was 7.6 months (95% CI: 6-10) compared to 3.4 months (95% CI: 2.8-4.1) following either ICI or chemotherapy alone, p=0.0005. A trend towards longer median EFS with use of CIT was seen in patients with BRAF wild-type [median 9 months (95% CI: 6-12)] compared to those harboring a BRAF mutation [median 6.5 months (95% CI: 1.8-9.1), p=0.29]. Side effects were similar among both groups. Conclusions: In MM patients who have failed anti-PD-1 therapy, the CIT combination showed favorable clinical outcomes and acceptable safety profile. This regimen should be considered for MM pts in this setting who have limited treatment options. [Table: see text]

Non-invasive biomarkers derived from the extracellular matrix associate with response to immune checkpoint blockade (anti-CTLA-4) in metastatic melanoma patients

BackgroundExcessive extracellular matrix (ECM) remodeling and a reactive stroma can affect T-cell infiltration and T-cell activity in the tumor and hereby influence response to immune checkpoint inhibitors (ICI). In the pursuit of finding biomarkers that predict treatment response, we evaluated the association between serum biomarkers of collagen and vimentin turnover and outcomes in metastatic melanoma patients treated with the anti-CTLA-4 antibody ipilimumab (IPI).MethodsType III collagen formation (PRO-C3), MMP-degraded type I, type III and type IV collagens (C1M, C3M and C4M), and citrullinated and MMP-degraded vimentin (VICM) were measured with ELISAs in serum from metastatic melanoma patients before (n = 66) and 3 weeks after (n = 52) initiation of IPI treatment. Biomarker levels were associated with Disease Control Rate (DCR) and survival outcomes.ResultsWe found that baseline levels of PRO-C3 (p = 0.011), C1M (p = 0.003), C3M (p = 0.013) and C4M (p = 0.027) were significantly elevated in patients with progressive disease (PD). Univariate Cox regression analysis identified high PRO-C3 (p = 0.021) and C4M (p = 0.008) as predictors of poor overall survival (OS) and the biomarkers remained significant when evaluated with other covariates (PRO-C3 (p = 0.049) and C4M (p = 0.046)). Multivariate analysis identified VICM as a predictor of longer OS (p = 0.026). Similarly, a high C3M/PRO-C3 ratio predicted for increased OS (p = 0.034). Only C3M (p = 0.003) and VICM (p < 0.0001) increased 3 weeks after treatment.ConclusionsECM and tissue remodeling quantified in pre-treatment serum were associated with response and survival outcomes in metastatic melanoma patients treated with IPI. This highlights the importance of addressing the ECM and stromal component non-invasively in future ICI studies.

Chemoimmunotherapy combination after PD-1 inhibitor failure to improve clinical outcomes in metastatic melanoma patients.

138Background: Clinical management of metastatic melanoma (MM) after PD-1 blockade failure remains challenging and lacks a standard of care. Chemo-immunotherapy (CIT) combinations have demonstrated...

Altered type III collagen turnover measured in pre-treatment serum predicts outcome in metastatic melanoma patients treated with Ipilimumab

Altered type III collagen turnover measured in pre-treatment serum predicts outcome in metastatic melanoma patients treated with Ipilimumab

Systemic immune signature of inflammation in metastatic melanoma (MM) patients treated with ipilimumab (IPI) and carboplatin/paclitaxel (CP).

185 Background: Only a subset of MM patients benefit from treatment with IPI. In an effort to increase response and identify predictive immune biomarkers, we combined IPI with CP. We here report a significant correlation between overall survival (OS) and biomarkers of a pre-existing inflammatory state. Methods: 30 patients were treated with C (AUC = 6) and P (175mg/m2) every 3 weeks x 5 and IPI (3mg/kg) every 3 weeks x 4. Blood was collected throughout. OS Kaplan–Meier curves were compared by the log-rank test. Cutoff thresholds defining high or low levels of chemokines, B cell populations and PD-1+CD8+ T cell populations were established from the mean value of a given variable from all patients. Neutrophil to Lymphocyte Ratio (NLR) and Systemic Immune Inflammation Index defined as Platelet x Neutrophil to Lymphocyte Ratio (SII) were calculated at baseline and tested for association with OS. SII ≥ 1375 and NLR ≥ 5 were considered as high risk groups. Results: Median OS was 16.2 months, with a 3-year OS of 36.7% for all patients. High levels of CCL3 (HR = 2.79, p = 0.0159), CCL4 (HR = 8.36, p &lt; 0.0001) and CXCL8 (HR = 3.52, p = 0.0037) were associated with worse OS. Advanced B cell differentiation before treatment was associated with worse patient outcomes. High levels of early differentiated Bm2 ( &gt; 57%) were strongly associated with better OS: HR = 0.26 p = 0.004 whereas high eBm5+Bm5 ( &gt; 14%) levels were strongly associated with worse OS: HR = 2.65, p = 0.029. Patients with higher proportions of PD-1+CD8+ T cells in circulation during treatment had poorer OS (HR = 3.84, p = 0.004) at week 10; (HR = 3.53, p = 0.005) at week 13 and (HR = 2.84, p = 0.040) at week 24. High risk SII (HR = 3.30, p = 0.0192) and NLR (HR = 2.367, p = 0.0486) were associated with worse OS. Conclusions: We have identified a significant correlation between pre-existing systemic inflammatory state and a poor response to IPI and CP. Specifically elevated CCL3, CCL4 and CXCL8, baseline B lymphocyte subset skewing, increased CD8+PD-1+ T lymphocytes, increased NLR and SII were all strongly associated to worse OS. Comprehensive immune monitoring provides evidence for new circulating biomarkers predicting outcome in MM patients treated with IPI and CP. Clinical trial information: NCT01676649.

1251P - Baseline neutrophil-to-lymphocyte ratio and its values monitored over time is associated with outcome of metastatic melanoma patients treated with immunotherapy

1251P - Baseline neutrophil-to-lymphocyte ratio and its values monitored over time is associated with outcome of metastatic melanoma patients treated with immunotherapy

Differences in immune profiles of metastatic melanoma patients treated with anti-CTLA-4 and anti-PD-1 combined immunotherapy.

51 Background: Immune checkpoint inhibitors targeting the cytotoxic T-lymphocyte antigen 4 (CTLA-4) and programmed cell death 1 (PD-1) receptor have significantly improved the outcomes of metastatic melanoma patients resulting in durable response and longer overall survival. However, while some patients exhibit a complete response to immunotherapy, others have demonstrated little to no response. The aim of this study is to examine the immune cell subsets between the good and poor responders to anti-CTLA-4 and anti-PD-1 combined immunotherapy in order to determine potential mechanisms of response and resistance. Methods: Multiplex immunofluorescent staining was performed on pre-treatment formalin-fixed, paraffin-embedded (FFPE) tissue samples from good and poor responders ( n= 17; n= 11 good responders, n= 6 poor responders) for markers including CD8, PD-1, PD-L1, FOXP3 and SOX10. Spectral image analysis was conducted via the Vectra 3.0 imaging system. Quantitative analysis was carried out using the inForm software. Gene signatures associated with the T-cell signalling pathways were identified following RNA sequencing of FFPE samples. Results: Good responders displayed significantly higher levels of baseline intratumoural PD-1 and PD-L1 expression in comparison to the poor responders ( P= 0.01 and P= 0.01 respectively), highlighting their roles as predictive biomarkers of response. Additionally, the CD8+ T-cell to PD-L1 ratio was significantly higher ( P= 0.001) in the tumours of the poor responders, indicating a distinction in the CD8+ T-cell phenotypes between the good and poor responders. Furthermore, analysis of the RNA sequencing data revealed a panel of immune signatures that have been implicated in prognosis and responsiveness to immunotherapy in melanoma. Conclusions: In summary, these findings provide insight into the possible biomarkers of response and resistance to immunotherapy, thus improving our understanding of the mechanisms driving variations in response.

Infliximab for ipilimumab-induced colitis: A series of 13 patients.

To review the outcomes of metastatic melanoma patients treated with infliximab for severe steroid-refractory colitis secondary to ipilimumab therapy. Immune-related colitis is a known potential adverse effect of ipilimumab, that causes significant morbidity and extended hospital stays. There are limited outcome data for patients treated with infliximab for ipilimumab-induced colitis refractory to corticosteroids. Management guidelines have been developed based on case study evidence only. A retrospective review of all patients administered infliximab for ipilimumab-induced colitis at South Australian public hospitals between October 2011 and April 2015. Resolution of colitis/diarrhea, duration of hospital stay, dosage regimen of infliximab used (single dose vs multiple dose) and surgical intervention if required. Between October 2011 and April 2015, 106 patients were dispensed ipilimumab from South Australian public hospitals for the treatment of metastatic melanoma. Thirteen were administered infliximab for severe, steroid-refractory colitis secondary to ipilimumab. Sixty-two percent received a single dose of infliximab only. Four patients achieved resolution of colitis symptoms at 1 month postinfliximab. Thirty-three percent required surgical intervention despite treatment with infliximab. One patient declined surgery and subsequently died due to bowel perforation. The average number of overnight bed days due to colitis was 27. This series of patients with severe ipilimumab-induced colitis suggests that despite treatment with infliximab a high proportion of patients do not achieve resolution of symptoms. Review of these cases has highlighted the absence of evidence-based guidelines to treat severe, steroid refractory colitis secondary to ipilimumab. Further prospective studies may clarify the role of infliximab for the treatment of ipilimumab-induced colitis.

1128P - CARAMEL study: Clinical prognostic biomarkers for ipilimumab-related outcome in metastatic melanoma patients

1128P - CARAMEL study: Clinical prognostic biomarkers for ipilimumab-related outcome in metastatic melanoma patients

Abstract 4363: Loss of PTEN promotes resistance to T cell-mediated immunotherapy

Abstract T cell-mediated immunotherapies are promising cancer treatments. However, most patients still fail to respond to these therapies. The molecular determinants of immune resistance are poorly understood. Here, we interrogated the role of loss of expression of the tumor suppressor, PTEN, in immune resistance. In preclinical studies, we found that silencing PTEN in tumor cells inhibited T cell-mediated tumor killing and decreased T cell trafficking into tumors. In clinical studies, we observed that tumors with loss of PTEN had significantly less CD8+ T cell infiltration than PTEN-present tumors. In addition, 26% of melanomas that did not yield successful TIL growth demonstrated PTEN loss, which was more frequent than was observed in tumors that yielded successful TIL growth (11%). We further validated the association between reduced number and impaired function of TIL with PTEN loss using another independent cohort, TCGA dataset for SKCM. More importantly, we analyzed clinical outcomes of metastatic melanoma patients treated with the FDA-approved anti-PD-1 antibodies. Our analysis demonstrates that a greater reduction in tumor burden was achieved by PD-1 blockade in PTEN present patients, when compared with PTEN absent patients. To decipher the factors mediating the immunosuppressive effects of PTEN loss, we determined the expression profiles of tumor cells with or without PTEN expression. Our results indicated that PTEN loss increased the production of immunosuppressive factors, including CCL2 and VEGF. Anti-VEGF blocking antibody improved anti-tumor activity of transferred tumor-reactive T cells and enhanced tumor infiltration of transferred T cells in PTEN-silenced tumors. These results suggest that loss of PTEN can facilitate the resistance of T cell-mediated immune responses by increasing the expression of immunosuppressive factors. Given that PTEN loss results in activation of the PI3K pathway, we evaluated the efficacy of immunotherapy in combination with a selective PI3Kβinhibitor to treat spontaneously developed BRAF mutant, PTEN null melanomas in genetically engineered mouse models. Our result showed that the combination of PI3Kβ inhibitor and anti-PD-1 significantly delayed tumor growth in tumor-bearing mice. Mice treated with this combination had a median survival time of 28 days, which is longer than the survival time of mice treated with either therapy. Increased numbers of T cells at tumor sites were found in mice receiving the combination therapy compared with mice receiving either agent alone. Taken together, our results demonstrate that PTEN loss contributes to the generation of immunosuppressive tumor microenvironment. Notably, this study provides the first direct clinical evidence to support the association between PTEN loss and poor clinical outcome in immunotherapy treated patients. In addition, our study indicates that inhibition of the PI3K-AKT pathway can improve the efficacy of immunotherapy in cancer. Citation Format: Weiyi Peng, Jie Qing Chen, Chengwen Liu, Shruti Malu, Caitlin Creasy, Michael Tetzlaff, Chunyu Xu, Jodi McKenzie, Chunlei Zhang, Xiaoxuan Liang, Leila Williams, Wanleng Deng, Guo Chen, Rina Mbofung, Alexander Lazar, Carlos Torres-Cabala, Zachary Cooper, Pei-Ling Chen, Trang Tieu, Stefani Spranger, Xiaoxing Yu, Chantale Bernatchez, Marie-Andree Forget, Cara Haymaker, Rodabe Amaria, Jennifer McQuade, Isabella Glitza, Tina Cascone, Haiyan Li, Lawrence Kwong, Timothy Heffernan, Jianhua Hu, Roland Bassett, Marcus Bosenberg, Scott Woodman, Willem Overwijk, Gregory Lizée, Jason Roszik, Thomas Gajewski, Jennifer Wargo, Jeffrey Gershenwald, Laszlo Radvanyi, Michael Davies, Patrick Hwu. Loss of PTEN promotes resistance to T cell-mediated immunotherapy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4363.

CARAMEL study: Clinical prognostic biomarkers for ipilimumab-related outcome in metastatic melanoma patients.

e21009Background: Ipilimumab is an inhibitor of CTLA4 receptor of T lymphocytes that has been approved by FDA both as first and second line treatment for patients with metastatic melanoma. Despite ...

Immunological markers and clinical outcome of advanced melanoma patients receiving ipilimumab plus fotemustine in the NIBIT-M1 study

ABSTRACTClinical activity was observed in metastatic melanoma (MM) patients treated with ipilimumab (IPI) combined with fotemustine (FTM) in the phase II NIBIT-M1 study. Peripheral blood mononuclear cells (PBMCs) and serum were collected from MM patients at pre- and at weeks 12 and 24 post-treatment. A comprehensive phenotypic and functional immunomonitoring of circulating T cells, and the detection of soluble immunoregulatory molecules was carried out and correlated with clinical outcome. The frequency at baseline and along the treatment of circulating T central memory cells expressing activation/differentiation markers, such as CD3+CD4+CD45RO+BTLA+, CD3+CD4+4–1BB or Th17 lymphocytes correlated with the clinical outcome of MM patients. Moreover, either the absence or the presence of soluble NKG2D ligands (ULBP-1 or −2) at baseline in the serum of MM patients enabled to discriminate subjects with long-term survival (median overall survival, (OS) = 33.6 mo for ULBP-1 and −2) from poor survivors (OS = 9.8 or 6.6 mo, respectively). Conversely, no significant association between the levels of soluble MICA, MICB and ULBP-3 and the clinical outcome of patients was observed. An inverse correlation between circulating levels of these molecules at baseline and frequency of either CD3+CD4+CD45RO+BTLA+ or Th17 or CD3+CD4+4–1BB+ T cells occurred in patients with a favorable clinical outcome. The simultaneous monitoring of different immune parameters, though validation in a large cohort of patients is needed, allowed to identify an association between phenotypic and soluble markers representing a possible predictive immunological signature for the clinical activity of IPI plus FTM.

Abstract 247: Comparing radiation therapy and ipilimumab to ipilimumab alone in metastatic melanoma patients

Abstract Purpose/Objective: With evidence suggesting ipilimumab and intracranial stereotactic radiosurgery (SRS) improves survival compared to SRS alone, we compared toxicity, response rates (RRs), and outcomes of metastatic melanoma patients receiving radiation (RT) and ipilimumab to ipilimumab alone. Methods and Materials: We reviewed records of metastatic melanoma patients receiving ipilimumab 3mg/kg between 2010-2014. RRs, measured by immune RECIST criteria, and toxicity were compared by Fischer's exact text. Overall survival (OS) was estimated by the Kaplan Meier method. Results: 61 patients received ipilimumab, with 35 (57.4%) also receiving radiation within 4 months of ipilimumab. The radiation cohort was similar at baseline except for greater systemic burden of disease (82.9% vs. 42.3%, p = 0.005), higher dexamethasone use (14.3% vs. 0%, p = 0.048), and more brain involvement (74.3% vs. 0% p&amp;lt;0.001). 92.3% of brain metastases received SRS. Grade 3 toxicity was not statistically different between cohorts (5.9% vs. 20.0%, p = 0.113); one grade 4 was experienced (1.6%), while no grade 5 occurred. While the ipilimumab alone group demonstrated a trend toward higher 1-year OS (49.4% vs. 73.2%, p = 0.090), the cohort did not have any patients with brain metastases; therefore, comparing only patients with extra-cranial metastases, 1-year OS was similar (76.2% vs. 73.2%, p = 0.587). RR between both cohorts was similar (20.0% vs. 11.5%, p = 0.494). Pre-ipilimumab absolute lymphocyte count greater than 1000 was the only significant predictor for increased RR in multivariable analysis (Odds Ratio: 8.56, 95% CI: 1.82-40.42; p = 0.007). Comparing 2-5 fractions of radiation to ipilimumab alone demonstrated a trend towards higher response rate (42.9% vs. 11.5%, p = 0.074). Conclusion: Despite poorer prognostic characteristics in the RT with ipilimumab cohort, toxicity, RR and OS were similar between the arms. Prospective studies investigating the ideal radiation fractionation to improve ipilimumab response rates are warranted. ALC &amp;lt; 1000 should be considered an exclusion criteria for these trials. Citation Format: Kirtesh R. Patel, Daniel E. Oliver, Derick Okwan-Dadu, Yuan Liu, Ragini R. Kudchadkar, David H. Lawson, Mohammad K. Khan. Comparing radiation therapy and ipilimumab to ipilimumab alone in metastatic melanoma patients. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 247. doi:10.1158/1538-7445.AM2015-247