Citations

Abstract PD-L1 expression levels derived from >16,000 samples guided the selection of tumor types likely to benefit from pembrolizuamb monotherapy in clinical trials. Although not fail-proof, FDA approvals for most of the prioritized indications speak to the power of RNA expression profiling and the value of large genomic datasets. See related article by Ayers et al., p. 1564

Abstract Background Early phase clinical trials evaluate the safety and efficacy of new treatments. The exclusion/inclusion criteria in these trials are usually rigorous and may exclude many patients seen in clinical practice. Our objective was to study the comorbidities limiting the participation of patients with breast, colorectal, or lung cancer in clinical trials. Materials and Methods We queried ClinicalTrials.gov on December 31, 2016. We reviewed the eligibility criteria of 1,103 trials. Logistic regression analyses were completed, and exclusion was studied as a binary variable. Results Out of 1,103 trials, 70 trials (6%) excluded patients >75 years of age, and 45% made no reference to age. Eighty-six percent of trials placed restrictions on patients with history of prior malignancies. Regarding central nervous system (CNS) metastasis, 416 trials (38%) excluded all patients with CNS metastasis, and 373 (34%) only allowed asymptomatic CNS metastasis. Regarding chronic viral infections, 347 trials (31%) excluded all patients with human immunodeficiency virus, and 228 trials (21%) excluded all patients with hepatitis B or C infection. On univariate analysis, chemotherapy trials were more likely to exclude patients with CNS metastasis and history of other malignancies than targeted therapy trials. Multivariate analysis demonstrated that industry-sponsored trials had higher odds of excluding patients with compromised liver function. Conclusion Many clinical trials excluded large segments of the population of patients with cancer. Frequent exclusion criteria included patients with CNS metastasis, history of prior malignancies, and chronic viral infections. The criteria for participation in some clinical trials may be overly restrictive and limit enrollment. Implications for Practice The results of this study revealed that most early phase clinic trials contain strict exclusion criteria, potentially excluding the patients who may be more likely to represent the population treated in clinical settings, leaving patients susceptible to unintended harm from inappropriate generalization of trial results. Careful liberalization of the inclusion/exclusion criteria in clinical trials will allow investigators to understand the benefits and drawbacks of the experimental drug for a broader population, and possibly improve recruitment of patients with cancer into clinical trials.

11534 Background: To date, there are no validated blood-based biomarkers of predicting response to PD-1 blockade. We previously reported that Bim is a downstream signaling molecule of the PD-1 pathway, and that measurement of Bim levels in circulating T-cells may predict and monitor responses to anti–PD-1 therapy in melanoma. We have identified the existence of sPD-L1 in cancer patients and showed that the sPD-L1 is biologically active and capable of triggering apoptosis in activated T-cells. Here we evaluated T cell Bim and sPD-L1 in the peripheral blood (PB) as biomarkers of response in a cohort of patients with metastatic melanoma and lung cancer undergoing anti-PD1 therapy. Methods: 60 pts treated with anti-PD-1 had PB collected at baseline and at radiographic tumor evaluation. Frequencies of Bim+ T cells and Bim median fluorescence intensity (MFI) were measured by flow cytometry in gated tumor-reactive CD11ahighPD1+ CD8+ T cells. We also measured levels of sPD-L1 at baseline and serially during treatment with sPD-L1 ELISA. Baseline Bim and sPD-L1 levels and percent change in Bim levels in patients (pts) who had a radiographic response (CR/PR) were compared to those who had progressive disease (PD) at 12 wks. Results: Similarly to previously reported preliminary data, pts with objective response (CR/PR, 15/60) after 4 cycles of anti-PD1 therapy had higher frequency of Bim T cells at baseline compared to pts with PD (16/60) (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). High baseline sPD-L1 were associated with progression on anti-PD1 therapy (mean 2.8 ng/mL vs. 0.7 ng/mL, p = 0.07, n = 13) and the levels increased by the first tumor assessment in patients resistant to anti-PD-1. Conclusions: Measurements of Bim and sPD-L1 levels may help to select patients who are likely to benefit from anti-PD1 monotherapy versus combinatorial strategies, and provide a new non-invasive way to monitor response to anti-PD-1 blockade. A larger validation study is underway.

TPS8584 Background: The first-line standard of care for the majority of patients (pts) with extensive-stage small-cell lung cancer (ES-SCLC) is platinum-based chemotherapy with etoposide, but survival outcomes remain poor (median OS, < 1 year) despite initial response rates ranging from 50-70%. Atezolizumab (atezo), an anti–PD-L1 mAb, prevents the binding of PD-L1 with its receptors PD-1 and B7.1 and restores anticancer T-cell activity. Tolerable safety with promising durability of response has been shown with atezo in pts with ES-SCLC: confirmed ORR was 6% (n = 1/17 [partial response]; DOR of 7 mo) by RECIST v1.1 and 24% by immune-related response criteria (irRC; n = 4/17, with 2 pts on atezo for ≥ 12 mo). Preliminary data also indicate the potential synergy between atezo and platinum-based chemotherapy in NSCLC, whereby durable responses may translate into improved survival over atezo alone. IMpower133 (NCT02763579), a global, Phase I/III, randomized, multicenter, double-blinded, placebo-controlled trial will evaluate the efficacy and safety of 1L atezo + carboplatin + etoposide compared with placebo + carboplatin + etoposide in treatment-naive pts with ES-SCLC. Methods: Pts with measurable (RECIST v1.1) ES-SCLC, who have ECOG PS 0-1 and no prior systemic anticancer treatment, are eligible for the study. Exclusion criteria include untreated CNS metastases and history of autoimmune disease. The study requires submission of tumor tissue, but pts will be enrolled regardless of biomarker status. Pts will be stratified by sex, ECOG PS and presence of treated brain metastases. Eligible pts will be randomized 1:1 to receive four 21-day cycles of atezo (1200 mg IV) or placebo in combination with carboplatin (AUC 5 mg/mL/min IV, d 1) and etoposide (100 mg/m2 IV, d 1-3), followed by maintenance therapy with atezo or placebo until PD per RECIST v1.1. Pts can continue with treatment until persistent radiographic PD, symptomatic deterioration or unacceptable toxicity. Co-primary endpoints are investigator-assessed PFS per RECIST v1.1 and OS. Secondary efficacy endpoints include investigator-assessed ORR and DOR. Safety and tolerability will also be assessed. Approximately 400 pts will be enrolled. Clinical trial information: NCT02763579.

TPS8582 Background: Argininosuccinate synthetase 1 (ASS1)-deficient malignant pleural mesothelioma (MPM) is sensitive to arginine deprivation therapy with pegylated arginine deiminase (ADI-PEG20), which also enhances the cytotoxicity of pemetrexed. The TRAP Phase 1 trial (NCT02029690) of ADI-PEG 20 combined with 1st-line pemetrexed (PEM) and cisplatin (CDDP) chemotherapy revealed a 94% disease control rate in non-epithelioid (biphasic and sarcomatoid) MPM subtypes characterized by a 75% rate of ASS1 loss. Thus, we plan to assess the efficacy of ADI-PEG20 or placebo combined with PEM and CDDP in patients (pts) with poor prognosis MPM in a randomized, placebo-controlled, double-blind phase 2/3 global trial. Methods: Up to 386 good performance (ECOG 0-1) pts with non-epithelioid malignant pleural mesothelioma will be enrolled in a phase 2/3 adaptive, biomarker-driven study design. Biopsies will be required prior to randomization: ASS1-agnostic pts will be enrolled initially (phase 2 stage) with an option to restrict enrolment to ASS1-deficient MPM (phase 3 stage). Pts will be randomized to receive weekly ADI-PEG20 (36 mg/m2 IM) or placebo with standard doses of PEM and CDDP for a maximum of 18 weeks (6 cycles) of treatment. Pts who develop CDDP toxicity may be switched to carboplatin. Pts will be assessed every 6 weeks using modified RECIST (RECIST 1.1 allowed for pts with significant extrathoracic disease). The primary endpoint for the phase 2 stage will be overall response rate (ORR) with secondary endpoints of overall survival (OS), safety and toxicity. The phase 2 will test ORR proportions with the placebo triplet set at 15% vs. 35% for the ADI-PEG 20 triplet, with a 1:1 randomization, 80% power. After recruitment of 176 pts, the phase 2 will convert to a phase 3 study with the primary endpoint of OS. In summary, ATOMIC-Meso is the first triplet chemotherapy study to assess the role of targeted arginine deprivation in aggressive subtypes of mesothelioma. Pt accrual has commenced across the US and Asia, with enrolment due in Europe and Australia by 2nd quarter of 2017. [Trial sponsored by Polaris Group]. Clinical trial information: NCT02709512.

TPS8581 Background: Malignant pleural mesothelioma (MPM) is an aggressive cancer with a 5-year overall survival (OS) rate of < 10%. At diagnosis, most patients (pts) have unresectable disease. Combination chemotherapy of cisplatin (or carboplatin as an alternative) + pemetrexed is the approved first-line standard of care. Phase 1 and 2 data suggest that targeting immune checkpoint pathways (eg, programmed death [PD]-1/PD-ligand 1 [PD-L1] and/or cytotoxic T-lymphocyte antigen-4 [CTLA-4]) may provide benefit with acceptable safety in MPM. In pts with previously treated, malignant mesothelioma, single-agent tremelimumab (a CTLA-4 inhibitor antibody) was active but did not improve OS vs placebo. In a phase 2 study of nivo (a fully human PD-1 immune checkpoint inhibitor antibody) in 34 pts with MPM that progressed after first-line platinum-based chemotherapy, 12-week disease control rate (DCR) was 50%, 5 pts had partial response, and 12 pts had stable disease. Given the data with single-agent CTLA-4 and PD-1 inhibitors and that CTLA-4 inhibition can induce PD-L1 expression, there is reason to anticipate synergy when combining CTLA-4 and PD-1 inhibitors in MPM. A phase 2 study assessing nivo alone and nivo + ipi (a CTLA-4 inhibitor antibody) in MPM is ongoing. CheckMate 743 (NCT02899299) is a phase 3 study that will evaluate the efficacy and safety of first-line nivo + ipi vs chemotherapy for MPM. Methods: Approximately 600 adult pts with unresectable MPM and ECOG performance status 0–1 will be randomized. Pts are ineligible if they have primary peritoneal, pericardial, or tunica vaginalis testis mesotheliomas; have active, untreated CNS metastases; or had received prior systemic therapy for pleural mesothelioma or a prior PD-1/PD-L1 or CTLA-4 checkpoint inhibitor antibody. Pts are randomized 1:1 to receive nivo + ipi or pemetrexed + cisplatin/carboplatin. Primary endpoints are OS and progression-free survival (PFS), assessed by blinded independent central review. Secondary endpoints are objective response rate (ORR), DCR, and correlation of PD-L1 expression level and efficacy (ORR, PFS, and OS). Clinical trial information: NCT02899299.

2533 Background: Many cancer clinical trials (CT) lack appropriate representation of specific patients populations, limiting the generalizability of the evidence obtained. Therefore, we determined the representation of ethnic minorities in oncology 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 US were excluded. Enrollment fraction (EF) was defined as the number of enrollees divided by the 2013 SEER database cancer prevalence. Chi-square test was used to estimate differences in categorical data. Results: Out of 1,012 CT, 310 (31%) reported ethnicity with a total of 55689 enrollees. Distribution by race and comparison with data from 1996-2002, US cancer prevalence and US census are described in the Table. Participation in CT varied significantly across ethnic groups, non-Hispanic Whites (NHW) 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 Americans (AA) and Hispanics (H) enrollment was observed when compared with historical data from 1996 to 2002. Hispanics were less represented in breast and prostate cancer CT contributing only to 3% and 1.5% of the study population; African Americans were less represented in lung (5.4%) and renal cell carcinoma (3%) trials. Asians were well represented and their recruitment doubled over the past 14 years (2% vs 5.3%). Conclusions: African Americans and Hispanics were less likely to be enrolled in CT. Comparing with historical data; we observed a decrease in minorities’ recruitment in 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 that adequately represent the U.S. cancer population. [Table: see text]