Dronca, Roxana

5082 Background: We evaluated the association of germ-line variation in 10 candidate genes important in prostate cancer biology (NKX3-1, JAK2, SLCO2B1, STAT3, CYP19A1, HSD17B4, TRMT11, PRMT3, HSD17B12, NCOA4) with failure of AA in advanced prostate cancer patients. Methods: Patients (N=619) were enrolled for genotyping at the time of AA failure. Candidate genes were selected from the literature and previous pilot studies in smaller cohorts which had identified variation in TRMT11 and HSD17B12 to be associated with AA failure. Genes were tagged using single nucleotide polymorphisms (SNPs) from HapMap with minor allele frequency of >5% and r2≥0.8. DNA was extracted from peripheral blood and genotyped using Illumina Veracode platform. The primary endpoint was time to failure on AA, defined as time from initiating continuous AA to two serial PSA increases over the nadir or clinical or imaging based progression, whichever came first. Principal component analysis was used for gene-levels tests. Association with the primary endpoint was assessed using proportional hazards regression models at the gene-level and at the SNP level. For SNP level results we estimated per allele (ordinal model) hazard ratios (HR) and 95% confidence intervals (CI) using Cox regression, adjusted for Gleason score (GS). Results: We successfully genotyped 60 SNPs (from 10 genes) in 519 subjects. The median age of the cohort was 71 years (range 43, 92). The GS distribution was 51% subjects with GS≥8; 33% with GS=7 and 17% with GS<7. Median time to AA failure for the cohort was 2.3 years (IQ range: 1.0-4.5). In gene level analyses adjusting for GS, TRMT11 (p=0.004), HSD17B12 (p=0.016), and JAK2 (p=0.044) genes were associated with time to AA failure. Four of the 18 genotyped SNPs in JAK2 were associated with AA failure after adjustment for GS (Table). Conclusions: Variation in the JAK2 gene is significantly associated with time to AA failure. Validation is needed to develop these as predictive biomarkers for AA in advanced prostate cancer. [Table: see text]

Background: A female survival advantage in cutaneous melanoma has been long recognized. However, whether this extends across all age groups, with risk stratification using the latest prognostic staging system or in the current era of efficacious systemic therapies is unknown. Therefore, we evaluated whether sex-based differences in melanoma survival persisted within a recent population-based patient cohort with consideration of these factors. Materials and Methods: We identified stage II−IV cutaneous melanoma patients from 2010 to 2014 Surveillance, Epidemiology, and End Results cancer registries data. We recalculated stage per American Joint Committee on Cancer 8th edition guidelines. Cancer-specific survival (CSS) was estimated by using the Kaplan–Meier method and multivariable Cox proportional hazards regression. Results: Of 16,807 patients (39.8% female), 8,990 were stage II, 4,826 stage III, and 2,991 stage IV at diagnosis. Unadjusted 3-/5-year CSS estimates for females versus males were 64.2% versus 59.7%, and 53.5% versus 49.9%, respectively, p ≤ 0.0001. Five-year CSS varied within each stage and across age strata of <45, 45 − 59, and ≥60 years. Within each stage, females <45 had better CSS than all other sex/age groups ( p < 0.0001). In multivariable analysis of stage II/III patients, female sex, younger age, and lower mitotic index retained favorable CSS prognostic significance ( p < 0.001). Conclusions: Sex-based differences in melanoma survival persist in a contemporary patient cohort staged with the latest prognostic system. These data may guide decision marking regarding adjuvant therapy, highlight the importance of including sex as a pre-specified clinical trial variable, and suggest that investigation of underlying biologic mechanisms may drive discovery of biomarkers and therapeutic targets to improve patient care.

83 Background: PT-112, the first pyrophosphate conjugate in Phase I/II clinical development, induces robust immunogenic cell death and is osteotropic, prompting study in mCRPC during Phase I. We report safety and efficacy findings in the mCRPC sub-population given PT-112 monotherapy (NCT02266745) or in combination with avelumab (“PAVE”) (NCT03409458, ongoing). Methods: Patients (pts) received PT-112 days 1, 8, 15 of a 28d cycle; pts on the PAVE combination also received 800 mg avelumab days 1 and 15; all enrolled during dose escalation or at PT-112 doses previously deemed safe. Pts on therapy (Tx) for ≥2 cycles or who stopped Tx due to progressive disease or treatment-related adverse events (TRAEs) were evaluated for exploratory efficacy. Results: 10 pts on PT-112 (200-420 mg/m2) and 18 pts on PAVE (150-200 mg/m2 PT-112) were evaluable for safety. The most common PT-112 TRAEs were thrombocytopenia (70%, grade (Gr) ≤3) and fatigue (40%, Gr ≤2) with mono-Tx; nausea (50%, Gr ≤2) and fatigue (39%, Gr ≤2) with PAVE. Mono-Tx pts had 6.5 median prior lines of Tx; 2/7 pts with measurable disease (MD) had reductions in target lesions; prostate specific antigen (PSA) declined in 3/10 pts, 1 with ≥50% reduction; and serum alkaline phosphatase (ALP) reductions were seen in 9/10 pts. PAVE pts had 5.5 median prior lines of Tx; radiographic reductions were seen in 2/9 pts with MD; PSA declined in 6/14 pts, 3 with ≥50% decrease, with 1 responder progression free 11.3 months (microsatellite stable). An additional response is ongoing at 4 mos, with 93% PSA decrease and 48% reduction in target lesions (PIK3CBmut & PTEN loss). 13/14 pts with bone metastases had ALP reductions. Pain improvement, opioid cessation and improved performance status were noted in both cohorts. Conclusions: PT-112 was well-tolerated with evidence of efficacy in mCRPC as mono-Tx and in combination with avelumab in heavily pre-treated pts. Bone pain improvement and nearly universal observation of ALP reduction suggest marked therapeutic activity of PT-112 in bone metastases. Serologic / RECIST responses and prolonged disease control in multiple pts substantiate further development of PT-112 in mCRPC. Clinical trial information: NCT02266745, NCT03409458.

696 Background: A number of treatments for metastatic renal cell carcinoma (RCC) have been FDA approved since December, 2005. Trials evaluating these agents excluded non-clear cell histologies and therefore the efficacy of these treatments remains unclear in patients (pts) with metastatic non-clear cell RCC (mncRCC). Methods: This is a single arm Phase II study designed to determine the efficacy of pazopanib in mncRCC. Treatment was pazopanib 800 mg by mouth daily until progression or intolerability of treatment. Dose reductions were allowed for toxicity with dose level -1 being 600 mg daily and dose level -2, 400 mg daily. Cycles were every 28 days. Main eligibility criteria included: (1) age ³ 18 years old; (2) histologic confirmation of ncRCC; (3) ECOG Performance Status (PS) 0, 1, or 2; (4) up to one prior treatment for mncRCC (5) measurable or non-measurable metastatic disease per RECIST criteria. The primary endpoint was overall survival rate at 12 months. Secondary endpoints were best tumor response rates after two cycles, PFS, OS and toxicity. Results: 38 pts were enrolled between May 16, 2013 and February 1, 2018. 35 pts were evaluable for primary endpoint. Median age 63 years old and 22/35 (62.9%) were male. Most common histology was papillary RCC, 14/35 (40%), and most common number of metastatic sites was 1. 29/35 (82.9%) had prior nephrectomy and 30/35 (85.7%) had no prior systemic therapy. Median number of cycles was 5. 12-month OS was 65.7% (90% CI, 50.5-78.9%). Best response in first 2 cycles: PR 11%, SD 60%, PD 9%, not evaluated 20%. Median PFS was 7.5 months (90% CI, 5.0-11.0); median OS 18.9 months (90% CI, 13.0-NE). Grade 3 / 4 AEs seen in 25 pts with hypertension, transaminitis and abdominal pain being most common (seen in >10%). Conclusions: There are limited data about the efficacy of available therapies for mncRCC. This study shows that pazopanib has similar efficacy compared to historical data in clinical trials using other TKIs in mncRCC. The safety profile of pazopanib in pts with mncRCC was found to be similar to that found in prior clinical trials studying pazopanib. Our findings warrant further investigation into the utility of pazopanib in metastatic ncRCC. Clinical trial information: NCT01767636.

Background The objective of this case cohort study was to describe our experience in the care of patients with immune checkpoint inhibitor–related acute interstitial nephritis (ICI-AIN) including rechallenge. Methods A descriptive case series of patients that received an ICI and had an AKI (defined as a ≥1.5-fold increase in serum creatinine) as an immune-related adverse event (irAE), with biopsy-proven or clinically suspected ICI-AIN from January 1, 2014 to December 1, 2018 at Mayo Clinic, Rochester. We studied details regarding diagnosis, clinical course, management, and outcomes of rechallenge of immunotherapy. Complete response (CR) was defined as return of kidney function back to baseline or <0.3 mg/dl above baseline creatinine; partial response (PR) was defined as creatinine >0.3 mg/dl from baseline, but less than twofold above the baseline by the end of steroid course. Results A total of 14 cases of biopsy-proven (35%) or clinically suspected (65%) ICI-AIN was identified. All patients had their ICI withheld and 12 patients received steroids. Steroid regimens were highly variable. The starting equivalent dose of prednisone was higher in those that had a CR versus a PR (median 0.77 mg/kg versus 0.66 mg/kg). Proton pump inhibitors (PPIs) were used in 11 patients and were stopped in eight (73%) patients at the time of the AKI event. A CR was seen in five (63%) of the eight patients who discontinued PPIs. Rechallenge was attempted in four of the 14 patients: three were successful with no recurrence of AKI, but one patient had recurrent AKI and fatal pneumonitis. Conclusions Careful review, withholding ICI and concomitant known AIN-inducing medications, along with prompt initial steroid management were the key in complete renal kidney recovery. A kidney biopsy should be strongly considered. Rechallenge of immunotherapy after a kidney irAE, although challenging, is possible and would need careful evaluation on an individual basis. Podcast This article contains a podcast at https://www.asn-online.org/media/podcast/K360/2020_01_30_KID0000152019.mp3

65 Background: The addition of chemotherapy to immune checkpoint inhibitors has been explored clinically in solid tumors in order to overcome one of the challenges of immunotherapy: clinical outcomes are variable, with only a subset of patients achieving durable responses. Further understanding of the immunoregulatory mechanisms of chemotherapy in the setting of immunotherapy is crucial for the development of optimal combinatorial chemo-immunotherapeutic strategies to improve clinical outcomes in patients with advanced cancer. Methods: Metastatic melanoma (MM) patients who failed anti-PD-1 single therapy were subsequently treated with paclitaxel and carboplatin in addition to PD-1 blockade. Using peripheral blood (PB) from MM patients and healthy donor, the phenotypic and functional changes in T cells induced by chemotherapy, in the setting of PD-1 blockade, were examined. Results: Paclitaxel and carboplatin, in combination with PD-1 blockade, were able to induce significant clinical responses in a subset of MM patients who were resistant to anti-PD-1 therapy alone. In patients who responded to this combination, a subset of tumor-reactive effector T cells (CD8+CD11a+PD1+GranzymeB+) survived the treatment, with increased frequency after the addition of chemotherapy. This T cell population preserved its effector phenotype, although ongoing PD-1 blockade was needed to improve its anti-tumor activity. In vitro experiments, using CD8+CD11a+PD1+GranzymeB+isolated from healthy donor PB, also demonstrated its ability to survive chemotherapy treatment. In addition, after cultured with chemotherapy, this T cell subset demonstrated higher cytotoxic T cell functions as well as increased chemotherapy efflux. Conclusions: Chemotherapy regulates a subset of tumor-reactive effector T cells (CD8+CD11a+PD1+GranzymeB+) and increases clinical efficacy of PD-1 blockade. This novel effector T cell population underlies the key cellular and molecular immunoregulatory mechanisms of chemotherapy. It serves as a meaningful marker to measure these collaborative effects and to develop the optimal chemo-immunotherapy strategy to improve clinical responses to current immune checkpoint blocking agents.

4 Background: Membrane expression of PD-L1 on tumor cells is associated with poor survival in patients with advanced malignancies including metastatic melanoma (MM). In addition, tumor-associated PD-L1 has been proposed as a predictor of response to anti-PD-1 therapy, although responses are observed in some cases of PD-L1 negative MM. We hypothesize that tumor-derived PD-L1 has additional systemic effects through the release of biologically active soluble forms of PD-L1 (sPD-L1) into the circulation, which further impedes the anti-tumor immune response and contributes to poor clinical outcomes in MM. Methods: We developed a sPD-L1 ELISA and biochemically confirmed the identity of the detected protein. We measured the levels of sPD-L1 in 276 patients with MM enrolled on 3 clinical trials who had stored pre-treatment plasma samples and 37 healthy volunteers (HV) undergoing blood donation at Mayo Clinic. We also measured sPD-L1 in baseline samples from 38 MM patients treated with anti-PD1 (pembrolizumab) 2 mg/kg every 3 weeks. ROC analysis was used to compute sPD-L1 concentration cut-off value and Wald test was used to asses the difference of overall survival (OS) in patients with low versus high sPD-L1 concentration. Results: We found that sPD-L1 levels were significantly elevated in MM patients compared with HV (p=0.0011). Mean sPD-L1 level in MM was 1.73 ng/mL (range: 0.13-18.29) compared with 0.77 ng/mL (range: 0.11–6.02) for HV. Patients with higher levels (>0.293 ng/mL) had a median OS of 11.3 months compared to 14.8 months for patients with sPD-L1 level ≤ 0.293 ng/mL (p=0.040). Similarly to tumor-related PD-L1 findings, patients who had clinical benefit (OR/PR/SD) after 4 cycles of anti-PD1 had higher sPD-L1 levels at baseline (2.1 vs. 1.1 ng/mL). Conclusions: To our knowledge, our study is the first to report a correlation of sPD-L1 with MM patient outcome, although a larger study is needed to establish the utility of sPD-L1 as an independent prognostic and possibly predictive biomarker.

Abstract Introduction: IL-15 has been used in clinical trials with PD-1 antibody to overcome cancer resistance to PD-1 monotherapy in cancer patients. However, it is not clear what T cell population would be expanded to mediate tumor control in IL-15 in combination with PD-1 antibody. We recently found CX3CR1+ cytotoxic CD8+ T cells, which increased in responders compared with non-responders after anti-PD-1 in melanoma patients, demonstrated an increased transcription of CD122 (IL2RB). Since CD122 is a subunit of IL-15 receptor, we hypothesized that IL-15 in combination with anti-PD-1 therapy may have the ability to expand CX3CR1+ cytotoxic CD8+ T cells for tumor control. Methods and findings: To examine whether IL-15 plus anti-PD-1 expand CX3CR1+ cytotoxic CD8+ T cells in tumor tissues, we treated tumor-bearing mice with IL-15/IL-15Rα complexes alone or with PD-1 antibody and measured the frequency of CX3CR1+Granzyme B+ CD8+ T cells. As only the combination therapy induced dramatic tumor regression, we found the highest increase of CX3CR1+Granzyme B+ CD8 T cells in tumor tissues in the group treated with IL-15 plus anti-PD-1 (28.87±3.19% vs. 7.91±1.32%, p&lt;0.01) compared with groups treated with either IL-15 alone or anti-PD-1 alone. In contrast to wild type mice, IL-15 plus anti-PD-1 did not suppress tumor growth in CX3CR1-KO mice. To determine whether IL-15 alone can also expand human CX3CR1+ cytotoxic CD8+ T cells, we cultured peripheral blood mononuclear cells (PBMCs) isolated from healthy donors (n = 5) with IL-15 for 24 hours in vitro. We found IL-15 (5 ng/mL) only modestly increased the frequency of CX3CR1+ Granzyme B+ CD8+ T cells than those cultured with no IL-15 (39.9±6.44% vs. 27.56±4.98%). To test whether this increase is due to enhanced proliferation of this subset of CD8+ T cells, we measured the expression of Ki-67, a cell proliferative marker, in CX3CR1+ CD8+ T cells by intranuclear staining. We found IL-15 modestly induced more proliferating CX3CR1+ CD8+ T cells in vitro culture compared with control group without IL-15 (6.25±0.54% vs. 0.91±0.25%). Summary: Taken together, we found IL-15 combined with anti-PD-1 therapy has the ability to significantly expand CX3CR1+ cytotoxic CD8+ T cells, however IL-15 alone may have limited ability to significantly expand this effector cell population. Our studies provide a new rational for combination therapy of IL-15 and PD-1 antibody to overcome cancer resistance for patients who did not respond to initial PD-1 therapy. Citation Format: Henan Zhang, Xin Liu, Siyu Cao, Lingling Chen, Susan Harrington, Ying Li, Aaron Mansfield, Sean Park, Yiyi Yan, Roxana Dronca, Haidong Dong. Expansion of CX3CR1+ cytotoxic CD8+ T cells provides a rationale for IL-15 in combination cancer therapy with PD-1 antibody [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4080.

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]