Citations

325 Background: Prostate cancer recurrence is detected by serum measurements of prostate specific antigen (PSA). Upon PSA elevation, locating sites of recurrence is important to guiding treatment and affecting patient outcomes. The imaging modalities in current practice have varying sensitivities and specificities and often miss early recurrent disease. 11C-choline positron emission tomography (11C-PET) may be able to detect occult disease and guide treatment decisions earlier in the clinical course. We assessed a case series of patients who underwent 11C-PET imaging and were identified to have thoracic disease to estimate the benefit of detection with this modality. Methods: Clinical records were retrospectively reviewed of seventy patients from thoracic oncology teams at Mayo Clinic in Rochester, Minnesota. Patients who had thoracic +/- extra-thoracic metastases on 11C-PET imaging were followed, noting changes in treatment and PSA trends to look for biochemical recurrence of disease. Results: Seventy patients with thoracic metastases discovered on 11C-PET imaging were initially identified. Median time to choline-avid disease from original diagnosis was 82 (IQR: 40-129) months with a median PSA at time of choline of 7.4 (IQR: 3.1-15.7). 11C-PET findings showed 28 patients with metastases limited to the thorax and 42 patients with thoracic and extra-thoracic metastases. After 11C-PET imaging, 1 patient underwent localized therapy only (radiation and surgery), 44 patients underwent systemic therapy only (chemotherapy or hormonal therapy), 19 patients underwent both localized (cryotherapy, radiation, or surgery) and systemic therapy, 3 patients underwent no further treatment, and 3 patients were lost to follow up. After a median follow-up of 36.5 (IQR: 13-52) months, 30 patients had no recurrence and 20 had evidence of biochemical recurrence. For those who underwent local therapy (N=21), 11 had no recurrence of disease. Conclusions: Choline-based imaging may earlier identify metastatic disease that is amenable to local therapy. Further studies are needed to validate the effectiveness of 11C-PET in identifying early, responsive metastatic prostate cancer and its utility in affecting patient outcomes.

Abstract Background: Despite the importance of diversity while studying new drugs, many cancer clinical trials (CT) lack appropriate representation of specific patient populations, limiting the generalizability of the evidence obtained. Therefore, we determined the representation of ethnic minorities, the elderly, and women in cancer CT. Methods: Enrollment data from all therapeutic trials reported as completed in clinicaltrial.gov from 2003 to 2016 were analyzed. CT in rare cancers (< 1% incidence) or with recruitment outside of the United States were excluded. Enrollment fraction (EF) was defined as the number of enrollees divided by the 2013 Surveillance Epidemiology and End Results (SEER) database cancer prevalence. Results: Out of 1,012 CT, 310 (31%) reported ethnicity with a total of 55,689 enrollees. 46,431 (83%) enrollees were non-Hispanic white, 3,270 (6%) African American, 2,982 (5.3%) Asian, 1,484 (2.6%) Hispanic, and 1,332 (2.4%) were classified as other. Participation in CT varied significantly across ethnic groups; non-Hispanic whites were more likely to be enrolled in CT (EF of 1.2%) than African Americans (EF of 0.7%, p <0.001) and Hispanics (EF of 0.4%, p <0.001). A decrease in African American (6% vs. 9.2%) and Hispanic (2.6% vs. 3.1%) enrollment was observed when compared with historical data from 1996 to 2002. Asians were well represented and their recruitment doubled over the past 14 years (2% vs. 5.3%). Hispanics were less represented in breast and prostate cancer CT, only contributing to 3% and 1.5% of the study population. African Americans were less represented in lung (5.4%) and renal cell carcinoma (3%) trials. Enrollees' median age was 60 years with 64% of patients <65 years of age. Younger patients (<65 years) were more likely to be enrolled in CT than the elderly (64% vs. 36%, p < 0.001). Lower recruitment of female patients was observed in CT for melanoma (35%), lung (39%), and pancreatic cancer (40%). Conclusions: African Americans, Hispanics, and the elderly were less likely to be enrolled in CT. Comparing with historical data, we observed a decrease in minorities' recruitment over the past 14 years. This change could be attributed to the increased complexity of CT and mandatory molecular testing as many minorities lack access to institutions with genetic-testing capacity. Future trials should take extra measures to recruit participants who adequately represent the U.S. cancer population. Citation Format: Narjust Duma, Jesus Vera-Aguilera, Yucai Wang, Jonas Paludo, Konstantinos Leventakos, Aaron Mansfield, Alex Adjei. Representation of minorities, the elderly, and women in over 1000 clinical trials [abstract]. In: Proceedings of the Tenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2017 Sep 25-28; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2018;27(7 Suppl):Abstract nr A26.

Abstract Despite unprecedented successes with immune checkpoint blockade in advanced cancers, these agents provide durable clinical benefit in only a subset of patients. In addition, the clinical management of patients receiving immune checkpoint blockade remains quite challenging due to the unpredictable and kinetically heterogeneous responses which can manifest as late responses, pseudoprogression, or hyperprogression in subsets of patients. The dynamics and heterogeneity of programmed cell death protein ligand 1 (PD-L1, aka B7-H1) expression confound its use as a predictive biomarker in cancer immunotherapy, but blood-based biomarkers have the potential to predict responders and detect mechanisms of resistance to immunotherapy. We previously reported that Bim (BH3-only protein) is a downstream signaling molecule of the PD-1 pathway, and that Bim levels in circulating tumor-reactive T-cells reflected patient responses to anti-PD-1 therapy in melanoma. We also discovered the existence of soluble PD-L1 (sPD-L1) in the plasma of cancer patients and showed a correlation of sPD-L1 with cancer stages in renal cell carcinoma and with prognosis in metastatic melanoma. Here we evaluated the frequency of tumor-reactive T cells with Bim expression along with effector memory profile and sPD-L1 as biomarkers of response in a new cohort of patients with metastatic melanoma and lung cancer undergoing anti-PD-1 therapy. We recruited 100 cancer patients treated with anti-PD-1 therapy who had peripheral blood collected at baseline and at each subsequent radiographic tumor evaluation. Frequencies of Bim+ and effector memory CD8+ T cells were measured by flow cytometry in gated tumor-reactive CD11a high PD1+ CD8+ T cells. We also measured levels of sPD-L1 in plasma at baseline and serially during treatment with ELISA. Baseline T cell markers and sPD-L1 levels and their percent changes in patients who had a radiographic response were compared to those who had progressive disease (PD). We found that patients with objective response after 4 cycles of anti-PD-1 therapy had higher frequency of Bim+ CD8+ T cells at baseline compared to patients with PD (mean 43% vs. 30%, P=0.0484). The frequencies of Bim+ T cells decreased significantly after the first 3 months of treatment in responders compared with progressors (mean -16% vs. + 40% P=0.0111). The frequency of effector memory CD8+ T cells also dramatically increased in responders in 3-6 months after anti-PD-1 therapy (mean 89% vs. 9.56%, p=0.002). High baseline sPD-L1 was associated with progression on anti-PD-1 therapy (mean 2.8 ng/mL vs. 0.7 ng/mL, p=0.07) or development of immune-related toxicities and the levels increased by 12 weeks in patients progressing on therapy. Conclusion: Measurements of T cell biomarkers (Bim and effector memory) and sPD-L1 levels provide a new noninvasive way to predict and monitor patient responses to anti-PD-1 monotherapy in melanoma and lung cancers. Note: This abstract was not presented at the conference. Citation Format: Roxana S. Dronca, Aaron Mansfield, Xin Liu, Susan Harrington, Elizabeth Enninga, Svetomir Markovic, Lisa Kottschade, Rob Mcwilliams, Matthew Block, Wendy Nevala, Michael Thompson, Haidong Dong. Blood-based T cell biomarkers and soluble PD-L1 predict responses and immune-related toxicity to PD-1 blockade in melanoma and lung cancer [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2017 Oct 1-4; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2018;6(9 Suppl):Abstract nr A38.

Abstract Background: Tumor surface PD-L1 (B7-H1) signals through T-cell surface receptor PD-1 to suppress antitumor immunity. PD-1 inhibitors like pembrolizumab block this pathway to prevent tumor escape from immunosurveillance. These PD-1 checkpoint inhibitors achieve objective response in 20-30% of patients with melanoma (1-3). As the majority of these patients are resistant to this treatment, there is a critical need to combat PD-1 checkpoint inhibitor resistance in melanoma. What is the mechanism of PD-1 checkpoint inhibitor resistance in melanoma? Our group has reported that soluble PD-L1 (sPD-L1, sB7-H1) is elevated in the serum of patients with PD-1 inhibitor-resistant melanoma and non-small cell lung cancer (NSCLC) (4). We have also shown that soluble PD-L1 is produced by cleavage from other tumor types and leads to apoptosis in CD8+ T-cells (5). The aim of this study is to confirm the source of sPD-L1 in human melanoma and its relation to outcomes. Methods: B7H1-expressing transgenic melanoma cells (Mel-B7H1) were treated with an array of protease inhibitors over 24 hours. Cells were then pelleted and supernatants were analyzed by ELISA for sPD-L1 (sB7-H1) production. Tumor serum samples were also analyzed by ELISA for sPD-L1 production.Tumor pathology slides from patients with melanoma (serum donors from the above study) were stained by immunohistochemistry with antibodies against proteases ADAM10 or ADAM17. Slides were visualized by microscopy for the presence of these antigens. Activated human CD8+ T-cells were cultured with recombinant human B7-H1 (PD-L1) protein, sPD-L1-rich, or sPD-L1-depleted supernatants from a tumor cell line in the presence of placebo or PD-1 checkpoint inhibitor antibodies. Cell survival was measured at 48 hours by flow cytometry.Results: ADAM10 inhibitor GI254023X, ADAM17 inhibitor TAPI-0, and broad metalloprotease inhibitor TAPI-2 inhibited Mel-B7H1 production of sB7H1 (p<0.001, 0.095, and 0.001 respectively). Specific inhibitors of other metalloproteases did not significantly alter sB7H1 production. PD-L1 transcription levels were not significantly altered. Tumor pathology slides from patients with high serum sPD-L1 exhibited high ADAM10 and/or ADAM17 staining. Conversely, tumors from patients with low-sPD-L1levels tended to exhibit low ADAM10 and/or ADAM17 staining. Recombinant PD-L1 and PD-L1-rich supernatants induced cell death of CD8+ T-cells, whereas PBS control solution and PD-L1-depleted supernatants did not. Supraphysiologic doses of pembrolizumab decreased cell death in PD-L1-rich supernatant-treated CD8+ T-cells. Conclusions: Matrix metalloprotease inhibitors ADAM10 and ADAM17 mediate sPD-L1 production from melanoma cells. In samples from patients with melanoma, immunohistochemical staining of these proteases in tumor tissue correlates with serum sPD-L1 levels. As we have shown previously, sPD-L1 induces apoptosis of activated CD8+ T-cells, which may explain PD-1 inhibitor resistance in most patients with melanoma.We posit that sPD-L1 outcompetes PD-1 inhibitors to suppress tumor immunosurveillance. Our results suggest that the combination of ADAM10/17 inhibitor and PD-1 checkpoint inhibitor may overcome this mechanism of PD-1 resistance in melanoma and other cancers. Future studies will determine (A) how a combined ADAM10/17 inhibitor and PD-1 inhibitor may function in clinical use, (B) how tumor-derived sPD-L1 signals downstream to cause apoptosis in T-cells, and (C) whether surface ADAM10/17 predict surface PD-L1 staining in melanoma. References: 1. Ribas et al., Lancet Oncol 2015;16(8):908–18. 2. Hamid et al., Ann Oncol 2016;27:6. 3. Weber et al., Lancet Oncol 2015:16(4):375–84. 4. Dronca et al., J Clin Oncol 2017:35(15):11534. 5. Orme et al., AACR Adv Malig Lymphoma 2018. Citation Format: Jacob J. Orme, Khalid Jazieh, Susan Harrington, Matthew Ball, Tariq U. Azam, Xin (Cindy) Liu, Tiancheng Xie, Aaron Mansfield, Roxana S. Dronca, Haidong Dong. Tumor-associated ADAM10 and ADAM17 produce soluble PD-L1 (sPD-L1, sB7-H1) and affect downstream tumor immunity – A resistance mechanism to PD-1 checkpoint blockade in melanoma [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A210.

Abstract In lung adenocarcinoma, gene fusion involving the anaplastic lymphoma kinase (ALK) gene leads to overexpression of its tyrosine kinase domain, which serves as the oncogenic driver in lung tumors carrying such a molecular alteration. Similar fusions involving ROS1, RET and NTRK are also found in lung cancer and tumors with oncogenic fusions often respond well to targeted therapy. However, these tumors do develop resistance to the targeting drug and patients eventually relapse while on treatment. Although newer drugs have been developed, it remains a challenge to effectively control cancer recurrence after targeted therapy. In vivo tumor models carrying these fusions, particularly those that have progressed while on targeted treatment, will help to facilitate further drug evaluations prior to their administration to the patient as well as offer an opportunity to better understand the molecular mechanisms driving disease onset, progression, and drug resistance in tumors carrying the fusion of interest. Here, we describe the first patient-derived tumor xenograft (PDX) carrying an STRN-ALK fusion. The patient was diagnosed with stage IV lung adenocarcinoma in 2011. She was initially treated with crizotinib and remained stable until 2015. At the time of disease progression, a biopsy was taken with patient consent under CT guidance from a chest wall mass using an 18-gauge needle and then implanted into two SCID-beige mice subcutaneously and into the fat pad of the kidney. Palpable tumor was observed in both mice at about 28 weeks post implantation and passaged at 36 weeks. They have been passaged two successive times and viably frozen. Pathologic analysis of the PDX showed that both tumors have the same mucinous morphology as observed in the original biopsy sample. RNA-seq and matepair analysis revealed that the tumors carry a rare fusion involving the first three exons of STRN and exon 20 to 3’ end of the ALK gene. The patient has been on ceritinib since January 2016 and remains stable as of last follow up. Several unique features contributed to the success of this study. 1) The metastatic chest wall lesion used for the PDX developed was easily accessible on the chest wall using a relative large 18-gauge needle for CT-guided biopsies. 2) The slow growth of the tumor biopsy mirrors the clinical course of the disease observed in the patient. 3) The patient remains clinically stable and continues to respond to TKi. The availability of a viable PDX tumor model for this rare STRN-ALK fusion offers a unique opportunity to identify the most appropriate drug for the patient at the time of disease progression as well as the opportunity to examine the unique molecular features associated with this rare ALK fusion. This work was supported in part by the National Foundation for Cancer Research Hillsberg Lung Cancer Translational Research Grant and by the Biomarker Discovery Program at the Mayo Clinic Center for Individualized Medicine. Citation Format: HongZheng Res, XiaoNan Hou, Karlyn E. Pierson, Patric Eiken, Asha Nair, PingYang Yang, Joanne Eunhee Yi, Aaron S. Mansfield, Jin Jen. Establishment of a unique patient-derived tumor model positive for STRN-ALK fusion from a patient with stage IV lung adenocarcinoma [abstract]. In: Proceedings of the Fifth AACR-IASLC International Joint Conference: Lung Cancer Translational Science from the Bench to the Clinic; Jan 8-11, 2018; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(17_Suppl):Abstract nr A17.

184 Background: Population level data regarding incidence of immune-related adverse events (irAE) is lacking. This study evaluated the frequency of irAEs among a large population of patients with non-small cell lung cancer (NSCLC) who received immune checkpoint inhibitors. Methods: Administrative claims data from a large U.S. commercial insurance database (OptumLabs Data Warehouse) were used to retrospectively identify patients with NSCLC who received PD-1 or PD-L1 inhibitors between January 1, 2015 to December 31, 2017. The frequencies of irAEs were reported, identified by having a new medical claim with a corresponding ICD-9 or ICD-10 code during the time period in which the patient was on immunotherapy. Results: Of 2,798 patients with NSCLC (median age at PD-(L)1 initiation: 69 years, interquartile range: 60-75, 1558 male [55.7%], 1240 [44.3%] female), 1,998 (71.4%) received nivolumab, 699 (25.0%) received pembrolizumab, and 101 (3.6%) received atezolizumab. Most patients (1463, 52.3%) received a PD-(L)1 inhibitor as second line therapy; the majority of patients (744) received alkylating agents and antimetabolites prior to receiving PD-(L)1 therapy. See Table 1 for frequencies of irAEs. Conclusions: The current study suggests that the frequencies of some irAEs related to immune checkpoint inhibitor therapies may be higher than those which were reported in the initial trials that led to the FDA approvals for immunotherapies. For example, hypophysitis was noted to occur in 0.6% of patients in the KEYNOTE-024 trial, but was identified in 2.4% of patients in this large cohort. Real world data may refine provider and patient expectations for outcomes beyond what is observed in clinical trials. [Table: see text]