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Purpose: Tumor mutational burden (TMB) has been shown to be predictive of survival benefit in patients with non–small cell lung cancer (NSCLC) treated with immune checkpoint inhibitors. Measuring TMB in the blood (bTMB) using circulating cell-free tumor DNA (ctDNA) offers practical advantages compared with TMB measurement in tissue (tTMB); however, there is a need for validated assays and identification of optimal cutoffs. We describe the analytic validation of a new bTMB algorithm and its clinical utility using data from the phase III MYSTIC trial. Patients and Methods: The dataset used for the clinical validation was from MYSTIC, which evaluated first-line durvalumab (anti–PD-L1 antibody) ± tremelimumab (anticytotoxic T-lymphocyte-associated antigen-4 antibody) or chemotherapy for metastatic NSCLC. bTMB and tTMB were evaluated using the GuardantOMNI and FoundationOne CDx assays, respectively. A Cox proportional hazards model and minimal P value cross-validation approach were used to identify the optimal bTMB cutoff. Results: In MYSTIC, somatic mutations could be detected in ctDNA extracted from plasma samples in a majority of patients, allowing subsequent calculation of bTMB. The success rate for obtaining valid TMB scores was higher for bTMB (809/1,001; 81%) than for tTMB (460/735; 63%). Minimal P value cross-validation analysis confirmed the selection of bTMB ≥20 mutations per megabase (mut/Mb) as the optimal cutoff for clinical benefit with durvalumab + tremelimumab. Conclusions: Our study demonstrates the feasibility, accuracy, and reproducibility of the GuardantOMNI ctDNA platform for quantifying bTMB from plasma samples. Using the new bTMB algorithm and an optimal bTMB cutoff of ≥20 mut/Mb, high bTMB was predictive of clinical benefit with durvalumab + tremelimumab versus chemotherapy.

Contains fulltext : 225429.pdf (Publisher’s version ) (Open Access) IMPORTANCE: Checkpoint inhibitors targeting programmed cell death 1 or its ligand (PD-L1) as monotherapies or in combination with anti-cytotoxic T-lymphocyte-associated antigen 4 have shown clinical activity in patients with metastatic non-small cell lung cancer. OBJECTIVE: To compare durvalumab, with or without tremelimumab, with chemotherapy as a first-line treatment for patients with metastatic non-small cell lung cancer. DESIGN, SETTING, AND PARTICIPANTS: This open-label, phase 3 randomized clinical trial (MYSTIC) was conducted at 203 cancer treatment centers in 17 countries. Patients with treatment-naive, metastatic non-small cell lung cancer who had no sensitizing EGFR or ALK genetic alterations were randomized to receive treatment with durvalumab, durvalumab plus tremelimumab, or chemotherapy. Data were collected from July 21, 2015, to October 30, 2018. INTERVENTIONS: Patients were randomized (1:1:1) to receive treatment with durvalumab (20 mg/kg every 4 weeks), durvalumab (20 mg/kg every 4 weeks) plus tremelimumab (1 mg/kg every 4 weeks, up to 4 doses), or platinum-based doublet chemotherapy. MAIN OUTCOMES AND MEASURES: The primary end points, assessed in patients with ≥25% of tumor cells expressing PD-L1, were overall survival (OS) for durvalumab vs chemotherapy, and OS and progression-free survival (PFS) for durvalumab plus tremelimumab vs chemotherapy. Analysis of blood tumor mutational burden (bTMB) was exploratory. RESULTS: Between July 21, 2015, and June 8, 2016, 1118 patients were randomized. Baseline demographic and disease characteristics were balanced between treatment groups. Among 488 patients with ≥25% of tumor cells expressing PD-L1, median OS was 16.3 months (95% CI, 12.2-20.8) with durvalumab vs 12.9 months (95% CI, 10.5-15.0) with chemotherapy (hazard ratio [HR], 0.76; 97.54% CI, 0.56-1.02; P = .04 [nonsignificant]). Median OS was 11.9 months (95% CI, 9.0-17.7) with durvalumab plus tremelimumab (HR vs chemotherapy, 0.85; 98.77% CI, 0.61-1.17; P = .20). Median PFS was 3.9 months (95% CI, 2.8-5.0) with durvalumab plus tremelimumab vs 5.4 months (95% CI, 4.6-5.8) with chemotherapy (HR, 1.05; 99.5% CI, 0.72-1.53; P = .71). Among 809 patients with evaluable bTMB, those with a bTMB ≥20 mutations per megabase showed improved OS for durvalumab plus tremelimumab vs chemotherapy (median OS, 21.9 months [95% CI, 11.4-32.8] vs 10.0 months [95% CI, 8.1-11.7]; HR, 0.49; 95% CI, 0.32-0.74). Treatment-related adverse events of grade 3 or higher occurred in 55 (14.9%) of 369 patients who received treatment with durvalumab, 85 (22.9%) of 371 patients who received treatment with durvalumab plus tremelimumab, and 119 (33.8%) of 352 patients who received treatment with chemotherapy. These adverse events led to death in 2 (0.5%), 6 (1.6%), and 3 (0.9%) patients, respectively. CONCLUSIONS AND RELEVANCE: The phase 3 MYSTIC study did not meet its primary end points of improved OS with durvalumab vs chemotherapy or improved OS or PFS with durvalumab plus tremelimumab vs chemotherapy in patients with ≥25% of tumor cells expressing PD-L1. Exploratory analyses identified a bTMB threshold of ≥20 mutations per megabase for optimal OS benefit with durvalumab plus tremelimumab. TRIAL REGISTRATION: ClinicalT rials.gov Identifier: NCT02453282.

The phase 3 MYSTIC study of durvalumab ± tremelimumab versus chemotherapy in metastatic non-small-cell lung cancer (NSCLC) patients with tumor cell (TC) programmed cell death ligand 1 (PD-L1) expression ≥ 25% did not meet its primary endpoints. We report patient-reported outcomes (PROs).Treatment-naïve patients were randomized (1:1:1) to durvalumab, durvalumab + tremelimumab, or chemotherapy. PROs were assessed in patients with PD-L1 TC ≥ 25% using EORTC Quality of Life Questionnaire (QLQ)-C30/LC13. Changes from baseline (12 months) for prespecified PRO endpoints of interest were analyzed by mixed model for repeated measures (MMRM) and time to deterioration (TTD) by stratified log-rank tests.There were no between-arm differences in baseline PROs (N = 488). Between-arm differences in MMRM-adjusted mean changes from baseline favored at least one of the durvalumab-containing arms versus chemotherapy (nominal P.01) for C30 fatigue: durvalumab (-9.5; 99% confidence interval [CI], -17.0 to -2.0), durvalumab + tremelimumab (-11.7; 99% CI, -19.4 to -4.1); and for C30 appetite loss: durvalumab (-11.9; 99% CI, -21.1 to -2.7). TTD was longer with at least one of the durvalumab-containing arms versus chemotherapy (nominal P.01) for global health status/quality of life: durvalumab (hazard ratio [HR] = 0.7; 95% CI, 0.5-1.0), durvalumab + tremelimumab (HR = 0.7; 95% CI, 0.5-1.0); and for physical functioning: durvalumab (HR = 0.6; 95% CI, 0.4-0.8), durvalumab + tremelimumab (HR = 0.6; 95% CI, 0.5-0.9) (both C30); as well as for the key symptoms of dyspnea: durvalumab (HR = 0.6; 95% CI, 0.5-0.9), durvalumab + tremelimumab (HR = 0.7; 95% CI, 0.5-1.0) (both LC13); fatigue: durvalumab + tremelimumab (HR = 0.6; 95% CI, 0.4-0.8); and appetite loss: durvalumab (HR = 0.5; 95% CI, 0.4-0.7), durvalumab + tremelimumab (HR = 0.7; 95% CI, 0.5-0.9) (both C30).Durvalumab ± tremelimumab versus chemotherapy reduced symptom burden and improved TTD of PROs, suggesting it had no detrimental effects on quality of life in metastatic NSCLC patients.

Many patients with metastatic non-small-cell lung cancer (mNSCLC) experience disease progression after first- and second-line treatment; more treatment options are required for these patients. ARCTIC, a phase III, randomized, open-label study, assessed durvalumab ± tremelimumab versus standard of care (SoC) as ≥ third-line treatment of mNSCLC.ARCTIC comprised two independent sub-studies. Study A: 126 patients with ≥25% of tumor cells (TCs) expressing programmed cell death ligand-1 (PD-L1) were randomized (1 : 1) to durvalumab [up to 12 months 10 mg/kg every 2 weeks (q2w)] or SoC. Study B: 469 patients with PD-L1 TC25% were randomized (3 : 2 : 2 : 1) to durvalumab + tremelimumab (12 weeks durvalumab 20 mg/kg + tremelimumab 1 mg/kg q4w then 34 weeks durvalumab 10 mg/kg q2w), SoC, durvalumab (up to 12 months 10 mg/kg q2w), or tremelimumab (24 weeks 10 mg/kg q4w then 24 weeks q12w). Primary end points: overall survival (OS) and progression-free survival (PFS) for durvalumab versus SoC (study A; descriptive only) and durvalumab + tremelimumab versus SoC (study B).Study A: median OS 11.7 (durvalumab) versus 6.8 (SoC) months {hazard ratio (HR) 0.63 [95% confidence interval (CI), 0.42-0.93]}; median PFS 3.8 (durvalumab) versus 2.2 (SoC) months [HR 0.71 (95% CI, 0.49-1.04)]. Study B: median OS 11.5 (durvalumab + tremelimumab) versus 8.7 (SoC) months [HR 0.80 (95% CI, 0.61-1.05); P = 0.109]. Median PFS of 3.5 months for both groups [HR 0.77 (95% CI, 0.59-1.01); P = 0.056]. Treatment-related grade 3/4 adverse events: 9.7% (durvalumab) and 44.4% (SoC; study A) and 22.0% (durvalumab + tremelimumab) and 36.4% (SoC; study B).In heavily pretreated patients with mNSCLC, durvalumab demonstrated clinically meaningful improvements in OS and PFS versus SoC (patients with PD-L1 TC ≥25%); numerical improvements in OS and PFS for durvalumab + tremelimumab versus SoC were observed (patients with PD-L1 TC25%). Safety profiles were consistent with previous studies.Clinicaltrials.gov identifier: NCT02352948.

TPS1105 Background: Patients (pts) with mTNBC have limited treatment options and poor prognosis. The combination of immune checkpoint inhibitors with chemotherapy shows promise, but only a subset of pts with mTNBC derive benefit, highlighting the need for new combinations. BEGONIA is an ongoing Simon 2-stage, multicenter, multi-arm platform study evaluating the safety and efficacy of D, an anti–PD-L1 monoclonal antibody, with or without P, in combination with novel oncology therapies as first-line treatment for mTNBC (NCT03742102). Dato-DXd is an antibody-drug conjugate (ADC) consisting of a humanized anti-trophoblast cell surface antigen 2 (TROP2) IgG1 monoclonal antibody, a stable tetrapeptide-based cleavable linker, and a topoisomerase I inhibitor payload. Dato-DXd displayed encouraging clinical activity with a manageable safety profile in heavily pretreated pts with metastatic NSCLC in the phase 1 TROPION-PanTumor01 (NCT03401385) study. TROP2 is highly expressed on breast and other epithelial tumors, and a TROP2 ADC showed activity in heavily pretreated pts with mTNBC (Bardia, NEJM 2019). Methods: Eligible female pts are aged ≥18 years with untreated unresectable, locally advanced or mTNBC, ≥12 months since prior taxane therapy, ECOG PS 0/1, adequate organ function, and ≥1 nonirradiated measurable lesion. For Arm 7, pts are excluded if they have clinically significant corneal disease, history of interstitial lung disease/pneumonitis, underlying pulmonary disorder, or prior treatment with an ADC containing a topoisomerase I inhibitor. Arm 7 will evaluate D (1120 mg) + Dato-DXd (6 mg/kg) given intravenously every 3 weeks until disease progression or unacceptable toxicity. Part 1 of each arm includes a total of 30 pts with a safety run-in (n=6) to observe dose-limiting toxicities, identify the recommended phase 2 dose (RP2D), and detect an efficacy signal for part 1 expansion. The primary endpoint of part 1 is safety and tolerability. Secondary endpoints include investigator-assessed objective response rate (ORR), duration of response, progression-free survival (PFS), and overall survival (OS). Once the RP2D has been established for part 1, a futility analysis will be performed with an option to expand the cohort to an additional 27 pts if expansion criteria are met. The primary endpoint for part 1 is ORR. Tumors will be assessed every 6 weeks per RECIST v1.1. Kaplan-Meier analysis will be used for PFS and OS. PD-L1 and TROP2 expression will be assessed by immunohistochemistry. Enrollment is ongoing. Clinical trial information: NCT03742102 .

Background In MYSTIC, an open-label, phase 3 trial of first-line D (anti-PD-L1) ± T (anti-CTLA-4) vs CT, while not statistically significant, a clinically meaningful improvement in overall survival (OS) was seen with D vs CT in patients with tumour cell PD-L1 expression ≥25% (TC ≥ 25% [primary analysis population]; D vs CT, HR 0.76 [97.54% CI 0.56–1.02]; D+T vs CT, HR 0.85 [98.77% CI 0.61–1.17]). Here we report results in a subpopulation of Asian patients. Methods Immunotherapy/CT-naive patients with metastatic NSCLC were randomized (1:1:1) to D (20 mg/kg q4w); D (20 mg/kg q4w) + T (1 mg/kg q4w ≤4 doses); or CT. In this analysis in a subpopulation of Asian patients, efficacy outcomes were evaluated in patients with PD-L1 TC ≥25%; safety was evaluated in all treated patients (regardless of PD-L1 expression). Results Of the 488 patients in the primary analysis population (PD-L1 TC ≥25%), 156 (32%) were Asian (D, 59; D+T, 50; CT, 47). Baseline characteristics in the Asian population were balanced between treatment arms. OS was improved in Asian patients (PD-L1 TC ≥25%) with D vs CT (HR 0.69 [95% CI 0.43–1.09]) and D+T vs CT (HR 0.64 [95% CI 0.40-1.03]); more patients receiving D or D+T remained in response at 6 months vs CT (Table). Grade ≥3 treatment-related adverse events (TRAEs) and any grade TRAEs leading to discontinuation occurred in 19.7% and 9.0% (D); 23.9% and 14.5% (D+T); 23.4% and 7.2% (CT) patients in the Asian subpopulation, respectively.Table474OTableDurvalumabDurvalumab + tremelimumabChemotherapyOverall (n = 163)Asian (n = 59)Overall (n = 163)Asian (n = 50)Overall (n = 162)Asian (n = 47)Median OS, mo16.3 (12.2–20.8)18.8 (9.2–28.4)11.9 (9.0–17.7)17.7 (11.6–27.3)12.9 (10.5–15.0)10.6 (7.0–14.6)24-mo OS rate, %38.343.835.442.022.722.3OS HR vs CT (95% CI)0.76 (0.56–1.02)*0.69 (0.43–1.09)0.85 (0.61–1.17)†0.64 (0.40–1.03)––ORR, n (%)58 (35.6)19 (32.2)56 (34.4)18 (36)61 (37.7)17 (36.2)Patients remaining in response (%) at6 mo66.968.467.652.732.434.312 mo61.362.254.926.318.0NROverall and Asian populations include patients with PD-L1 TC ≥25%;.*97.54% CI; †98.77% CI; ORR occurred on June 1, 2017; DoR, duration of response; NR, not reached; ORR, objective response rate; OS, overall survival. Conclusions Durvalumab resulted in a favourable HR for OS compared to CT in patients with PD-L1 TC≥25% in the Asian subpopulation, which was consistent with the primary analysis population. OS HR for D+T vs CT appeared to be more favourable in the Asian subpopulation compared to the primary analysis population, although results should be interpreted with caution due to small sample sizes. The safety profile of D±T in the subpopulation of Asian patients was manageable and consistent with the primary analysis population. Clinical trial identification NCT02453282. Editorial acknowledgement Medical writing support, which was in accordance with Good Publication Practice (GPP3) guidelines, was provided by Beena John, PhD of Cirrus Communications (Macclesfield, UK), an Ashfield company, and was funded by AstraZeneca. Legal entity responsible for the study AstraZeneca. Funding AstraZeneca. Disclosure B.C. Cho: Advisory / Consultancy, Research grant / Funding (institution): AstraZeneca; Advisory / Consultancy, Research grant / Funding (institution): Novartis; Research grant / Funding (institution): Bayer; Research grant / Funding (institution): MOGAM Institute; Advisory / Consultancy: Boehringer Ingelheim; Advisory / Consultancy: Roche; Advisory / Consultancy: BMS; Advisory / Consultancy, Research grant / Funding (institution): Ono; Advisory / Consultancy, Research grant / Funding (institution): Yuhan; Advisory / Consultancy, Research grant / Funding (institution): Janssen; Research grant / Funding (institution): Champions Oncology; Research grant / Funding (institution): Dong-A ST; Research grant / Funding (institution): Dizal Pharma; Advisory / Consultancy, Research grant / Funding (institution): MSD; Advisory / Consultancy: Pfizer; Advisory / Consultancy: Eli Lilly; Advisory / Consultancy: Takeda; Shareholder / Stockholder / Stock options: TheraCanVac Inc. K.H. Lee: Honoraria (self), Advisory / Consultancy: AstraZeneca; Honoraria (self), Advisory / Consultancy: MSD; Honoraria (self), Advisory / Consultancy: BMS. S. Lucien Geater: Honoraria (self), Research grant / Funding (institution): AstraZeneca; Honoraria (self), Research grant / Funding (institution): Roche; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Boehringer Ingelheim; Research grant / Funding (institution): Novartis; Research grant / Funding (institution): Samsung. T.V. Ngoc: Research grant / Funding (institution): AstraZeneca; Research grant / Funding (institution): GSK; Research grant / Funding (institution): Novartis. S. Clarke: Advisory / Consultancy, Travel / Accommodation / Expenses: AstraZeneca. S. Kuyama: Speaker Bureau / Expert testimony, Lecture fees: AstraZeneca; Speaker Bureau / Expert testimony, Lecture fees: Pfizer; Speaker Bureau / Expert testimony, Lecture fees: Eli Lilly; Speaker Bureau / Expert testimony, Lecture fees: Boehringer Ingelheim; Speaker Bureau / Expert testimony, Lecture fees: MSD; Speaker Bureau / Expert testimony, Lecture fees: Taiho; Speaker Bureau / Expert testimony, Lecture fees: Chughai. K. Nakagawa: Honoraria (institution), Research grant / Funding (institution): MSD / Takeda / SymBio Pharmaceuticals / Daiichi Sankyo; Honoraria (self), Research grant / Funding (institution): Eli Lilly Japan; Honoraria (self), Research grant / Funding (institution): BMS; Honoraria (self), Research grant / Funding (institution): Taiho /Ono / Chughai; Honoraria (self), Research grant / Funding (institution): AstraZeneca / Astellas Pharma / Novartis / Nippon Boehringer Ingelheim / Pfizer Japan; Research grant / Funding (institution): Merck Serono / ICON Japan /PAREXEL / IQVIA Services Japan / A2 Healthcare / AbbVie; Research grant / Funding (institution): EP-CRSU / Linical / Otsuka Pharmaceuticals / EPS International / Quintiles / CMIC Shift Zero / Eisai / Kissei Pharmaceutical ; Research grant / Funding (institution): Kyowa Hakko Kirin / EPS Corporation / Bayer Yakuhin / inVentiv Health Japan / Gritstone Oncology / GSK / Yakult Honsha / Covance ; Honoraria (self): Kyorin Pharmaceutical / CareNet / Nichi-Iko Pharmaceutical / Hisamitsu Pharmaceutical / Yodosha / Clinical Trial / Reno Medical / Nanzando / Medical Review; Honoraria (self): Medicus Shuppan / Ayumi Pharmaceutical / Thermo Fisher Scientific / Yomiuri Telecasting Corporation / Nikkei Business Publications. F. Liu: Full / Part-time employment, Full-time employee: AstraZeneca. D. Clemett: Full / Part-time employment, Full-time employee: AstraZeneca. U. Scheuring: Full / Part-time employment, Full-time employee: AstraZeneca. S. Peters: Honoraria (self), Advisory / Consultancy: AbbVie; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Amgen; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution): AstraZeneca / Pfizer; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Bayer / Seattle Genetics and Takeda; Honoraria (self), Advisory / Consultancy: Biocartis; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution): Boehringer Ingelheim; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution): BMS; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Clovis; Honoraria (self), Advisory / Consultancy: Daiichi Sankyo / Regeneron / Sanofi; Honoraria (self), Advisory / Consultancy: Debiopharm; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony: Eli Lilly; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution): F Hoffmann-La Roche; Honoraria (self), Advisory / Consultancy: Foundation Medicine; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Illumina; Honoraria (self), Advisory / Consultancy: Janssen; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution): Merck Sharp & Dohme; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Merck Serono; Honoraria (self), Advisory / Consultancy: Merrimack; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution): Novartis; Honoraria (self), Advisory / Consultancy: Pharma Mar. N. Rizvi: Advisory / Consultancy: AstraZeneca; Advisory / Consultancy: Genentech/Roche; Advisory / Consultancy: Novartis; Advisory / Consultancy: Merck Sharp & Dohme; Advisory / Consultancy: BMS; Advisory / Consultancy: Pfizer; Advisory / Consultancy: Lilly; Advisory / Consultancy: AbbVie; Advisory / Consultancy: Regeneron; Advisory / Consultancy: Janssen; Leadership role, Shareholder / Stockholder / Stock options: ARMO BioSciences; Shareholder / Stockholder / Stock options: Gritstone Oncology. All other authors have declared no conflicts of interest.

Background PD-L1 expression determined by immunohistochemistry (IHC) can be a useful biomarker to assess the likelihood of benefit with anti-PD-1/PD-L1 therapies in pts with mNSCLC. Understanding the impact of sample type (primary tumour or metastatic) on predictivity of benefit will inform the suitability of such samples for clinical testing. MYSTIC (NCT02453282) was an open-label, phase III study of durvalumab (D) ± tremelimumab vs chemotherapy (CT) as first-line treatment for mNSCLC; stratification factors for randomisation included tumour cell (TC) PD-L1 expression (≥25% vs Methods All pts enrolled in MYSTIC were assessed centrally for TC staining for PD-L1 from tissue samples acquired Results Of 1118 pts randomised, 716 (64.0%) provided a primary tumour sample and 402 (36.0%) provided a metastatic sample. The prevalence of PD-L1 TC ≥25% assessed using primary vs metastatic samples was 43.0% vs 44.8% (p = 0.569). Outcomes in pts with TC ≥ 25% determined using samples of each type are shown. Table . 1491P Primary tumour sample PD-L1 TC ≥25% Metastatic sample PD-L1 TC ≥25% Durvalumab (n = 104) Chemotherapy (n = 100) Durvalumab (n = 59) Chemotherapy (n = 62) Median OS, months 15.8 13.0 20.5 12.9 HR for OS vs CT (95% CI) 0.81 (0.59–1.11) - 0.65 (0.41–1.01) - 24-month OS, % 33.4 19.1 46.9 28.6 ORR, % 30.8 37.0 44.1 38.7 Median DoR, months Not reached 4.4 Not reached 4.1 Conclusions In MYSTIC, PD-L1 TC ≥25% prevalence was similar using primary or metastatic samples. Favourable HRs for OS with D vs CT were seen in pts with TC ≥ 25% expression as determined in either the primary tumour or a metastatic site. Results should be interpreted with caution given the retrospective nature of the analysis. Clinical trial identification NCT02453282 (release date: 25 May 2015). Editorial acknowledgement Samantha Holmes, PhD, of Cirrus Communications (Macclesfield, UK), an Ashfield company, funded by AstraZeneca and in accordance with Good Publication Practice (GPP3) guidelines. Legal entity responsible for the study AstraZeneca PLC. Funding AstraZeneca. Disclosure N. Reinmuth: Honoraria (self), Travel / Accommodation / Expenses: BMS; Honoraria (self), Travel / Accommodation / Expenses: AstraZeneca; Honoraria (self), Travel / Accommodation / Expenses: Bohringer Ingelheim; Honoraria (self), Travel / Accommodation / Expenses: Roche; Honoraria (self), Travel / Accommodation / Expenses: MSD; Honoraria (self), Travel / Accommodation / Expenses: Takeda; Honoraria (self): Pfizer. A. Boothman: Shareholder / Stockholder / Stock options, Full / Part-time employment: AstraZeneca. B.C. Cho: Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self): Novartis; Honoraria (self), Advisory / Consultancy, Research grant / Funding (self): AstraZeneca; Advisory / Consultancy: Boehringer Ingelheim; Advisory / Consultancy: Roche; Advisory / Consultancy: BMS; Advisory / Consultancy, Research grant / Funding (self): Ono; Honoraria (self), Advisory / Consultancy, Research grant / Funding (self): Yuhan; Advisory / Consultancy: Pfizer; Advisory / Consultancy: Eli Lilly; Honoraria (self), Advisory / Consultancy, Research grant / Funding (self): Janssen; Speaker Bureau / Expert testimony: Takeda; Advisory / Consultancy: MSD; Shareholder / Stockholder / Stock options: TheraCanVac Inc; Honoraria (self), Research grant / Funding (self): Bayer; Honoraria (self), Research grant / Funding (self): MOGAM Institute; Honoraria (self), Research grant / Funding (self): Dong-A ST; Honoraria (self), Research grant / Funding (self), Licensing / Royalties: Champions Oncology; Honoraria (self), Research grant / Funding (self): Dizal Pharma; Honoraria (self), Research grant / Funding (self): MSD. K.H. Lee: Research grant / Funding (institution): AstraZeneca. M. Ahn: Advisory / Consultancy, Research grant / Funding (institution), Spouse / Financial dependant: AstraZeneca; Advisory / Consultancy, Research grant / Funding (institution): AbbVie; Advisory / Consultancy, Research grant / Funding (institution): Amgen; Research grant / Funding (institution): BIND Biosciences; Research grant / Funding (institution): Celgene; Research grant / Funding (institution): Eli Lilly; Research grant / Funding (institution): Genentech; Research grant / Funding (institution): MedImmune; Research grant / Funding (institution): Novartis; Research grant / Funding (institution): Pfizer. M. Scott: Shareholder / Stockholder / Stock options, Full / Part-time employment: AstraZeneca. J. Whiteley: Shareholder / Stockholder / Stock options, Full / Part-time employment: AstraZeneca. J. Walker: Full / Part-time employment: AstraZeneca. V. Karwe: Full / Part-time employment: AstraZeneca. P. Mukhopadhyay: Shareholder / Stockholder / Stock options, Full / Part-time employment: AstraZeneca. P. Thiyagarajah: Full / Part-time employment: AstraZeneca. U. Scheuring: Full / Part-time employment: AstraZeneca. N. Rizvi: Advisory / Consultancy: AstraZeneca; Advisory / Consultancy: Merck; Advisory / Consultancy: Roche; Advisory / Consultancy: Bristol-Myers Squibb; Advisory / Consultancy: Novartis; Advisory / Consultancy: Pfizer; Advisory / Consultancy: Lilly; Advisory / Consultancy: AbbVie; Advisory / Consultancy: Merck KGaA; Advisory / Consultancy: Regeneron; Shareholder / Stockholder / Stock options: Gritstone Oncology; Shareholder / Stockholder / Stock options: ARMO Biosciences. All other authors have declared no conflicts of interest.

Background High TMB is predictive of PFS benefit with anti-PD-(L)1 ± anti-CTLA-4 therapy in mNSCLC. Preliminary results from MYSTIC (NCT02453282), an open-label, Phase III trial of first-line durvalumab (D; anti-PD-L1), ± tremelimumab (T; anti-CTLA-4), vs platinum-based chemotherapy (CT) in mNSCLC, indicate that blood TMB (bTMB, ≥16 mut/Mb; GuardantOMNI [Guardant Health]) from circulating tumor DNA (ctDNA) correlates positively with tissue (t) TMB (≥10 mut/Mb) (Spearman’s correlation coefficient = 0.6) and is predictive of survival benefit with D±T vs CT. Efficacy outcomes were assessed using additional exploratory cut-offs for bTMB and ≥10 mut/Mb for tTMB. Methods Pts with EGFR and ALK wild-type, immunotherapy/CT-naïve mNSCLC were randomized (1:1:1) to D (20 mg/kg i.v. q4w); D (20 mg/kg i.v. q4w) + T (1 mg/kg i.v. q4w up to 4 doses); or CT. bTMB was evaluated with the GuardantOMNI platform. tTMB was evaluated with the FoundationOne tissue NGS platform. bTMB cut-off was defined as ≥20 mut/Mb (bTMB≥20). Data cut-off: Oct 4, 2018 (OS); Jun 1, 2017 (PFS). Results 1118 pts were randomized. Baseline sample datasets were: bTMB 809; tTMB 460 pts, with baseline characteristics balanced between treatment arms. bTMB≥20 was associated with improved OS (D+T vs CT: HR 0.49 [95% CI 0.32, 0.74]; D vs CT: HR 0.72 [95% CI 0.50, 1.05]) and PFS (D+T vs CT: HR 0.53 [95% CI 0.34, 0.81]; D vs CT: HR 0.77; [95% CI 0.52, 1.13]); 24-mo survival: D+T 48.1% (95% CI 35.5, 59.7), D 33.8% (95% CI 23.4, 44.5) and CT 19.4% (95% CI 11.0, 29.5). Data for tTMB are shown (table). Additional cut-offs will be presented. Conclusion MYSTIC provides the most comprehensive data set to date supporting TMB as a predictive biomarker of OS benefit with immunotherapy. In exploratory analyses, bTMB≥20 was associated with OS and PFS benefit with D±T vs CT, with the greatest magnitude of benefit observed for pts receiving D+T. bTMB ≥20 mut/MbbTMB Citation Format: Solange Peters, Byoung Chul Cho, Niels Reinmuth, Ki Hyeong Lee, Alexander Luft, Myung-Ju Ahn, Paul Baas, Manuel Cobo Dols, Alexey Smolin, David Vicente, Vladimir Moiseyenko, Scott J. Antonia, Kazuhiko Nakagawa, Sarah B. Goldberg, Edward Kim, Rajiv Raja, Philip Brohawn, Delyth Clemett, Piruntha Thiyagarajah, Urban Scheuring, Feng Liu, Naiyer Rizvi. Tumor mutational burden (TMB) as a biomarker of survival in metastatic non-small cell lung cancer (mNSCLC): Blood and tissue TMB analysis from MYSTIC, a Phase III study of first-line durvalumab ± tremelimumab vs chemotherapy [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 CT074.

9016 Background: MYSTIC, an open-label, Ph3 trial of first-line D (anti-PD-L1) ± T (anti-CTLA-4) vs platinum-based CT, showed an improvement in OS with D vs CT in pts with tumor cell PD-L1 expression ≥25% (PD-L1 TC ≥25%; HR 0.76 [97.54% CI 0.56–1.02], p = 0.036). Exploratory analyses showed bTMB was a predictive biomarker for OS with D±T vs CT. We report further exploratory analyses of OS according to PD-L1 and bTMB. Methods: Immunotherapy/CT-naïve pts with mNSCLC were randomized (1:1:1) to D, D+T or CT. bTMB levels (mut/Mb) were evaluated with the GuardantOMNI platform (Guardant Health), and PD-L1 TC expression with the VENTANA PD-L1 (SP263) IHC assay. Results: D improved OS vs CT in pts with PD-L1 TC ≥25% across bTMB levels (PD-L1 TC ≥25%/bTMB≥20 HR 0.79 [95% CI 0.45, 1.39]; PD-L1 TC ≥25%/bTMB < 20 HR 0.64 [95% CI 0.45, 0.90]). In contrast, D+T improved OS vs CT in pts with bTMB≥20 across different PD-L1 TC expression levels (Table; PD-L1 TC ≥25%/bTMB≥20 HR 0.44 [95% CI 0.23, 0.84]; PD-L1 TC < 1%/bTMB≥20 HR 0.42 [95% CI 0.17, 0.97]). Additional cutoffs and outcomes in subgroups defined by both biomarkers will be presented. Conclusions: These exploratory analyses from MYSTIC support PD-L1 TC expression as an appropriate predictive biomarker for OS with D vs CT, while suggesting bTMB as a predictive biomarker for OS with D+T in mNSCLC. These biomarkers appear to be independent and both may be important for mNSCLC treatment decisions. Interpretation of these data may be limited by small sample sizes; further investigations are warranted. Clinical trial information: NCT02453282. [Table: see text]

9048 Background: MYSTIC, an open-label, Phase 3 trial of first-line D (anti-PD-L1) ± T (anti-CTLA-4) vs platinum CT in mNSCLC, showed an improvement in overall survival (OS) with D vs CT in pts with tumor cell PD-L1 expression ≥25% (TC ≥25% [primary analysis population]; D vs CT, HR 0.76 [97.54% CI 0.56–1.02], p = 0.036; D+T vs CT, HR 0.85 [98.77% CI 0.61–1.17], p = 0.202). Here we summarize PROs from MYSTIC. Methods: Immunotherapy/CT-naïve mNSCLC pts were randomized (1:1:1) to D, D+T, or CT. Symptoms, function, and global health status/quality of life (QoL) were assessed using the EORTC QLQ-C30 v3 questionnaire and its lung cancer module, QLQ-LC13. A change in score from baseline ≥10 points was predefined as clinically meaningful (CM). Mean changes from baseline (over 12 mos) for prespecified symptoms were analyzed using a mixed model for repeated measures (MMRM). Time from randomization to the first CM deterioration (TTD) was analyzed. Results: Among pts with PD-L1 TC ≥25% (n = 488), there were no differences between arms in symptoms, function, or global health status/QoL at baseline. Compliance with completing the questionnaires was ≥60% to wk 120 in the D±T arms, and to wk 40 (C30) and wk 44 (LC13) in the CT arm. MMRM analysis showed significant between-arm differences in changes from baseline in favor of D for fatigue (difference vs CT −9.5) and appetite loss (−11.9; CM), and D+T for fatigue (−11.7; CM). Significantly longer TTD (median, mos) was seen with D and D+T vs CT for appetite loss (12.8 and 5.6 vs 4.5), constipation (14.6 and 9.0 vs 5.5), nausea/vomiting (16.7 and 9.7 vs 4.5), and dyspnea (10.6 and 7.4 vs 5.6); D vs CT for diarrhea (16.3 vs 9.0), insomnia (9.3 vs 6.2), and hemoptysis (not reached vs 10.3); and D+T vs CT for fatigue (5.6 vs 2.0). Significantly longer TTD (median, mos) was also seen with D and D+T vs CT for function (cognitive [9.1 and 6.6 vs 5.2], physical [9.0 and 7.4 vs 4.2], role [D vs CT only; 7.3 vs 3.7], social [12.9 and 5.4 vs 5.2]), and global health status/QoL (5.9 and 6.8 vs 5.5). Conclusions: Pts with PD-L1 TC ≥25% treated with D±T had a reduced symptom burden over time and longer TTD for symptoms, function, and global health status/QoL compared to pts receiving CT. Clinical trial information: NCT02453282.

It has been shown that the addition of a beta-adrenergic catecholamine to a trout red blood cell suspension induces a 60-100-fold increase of sodium permeability resulting from the activation of a cAMP-dependent Na+/H+ antiport. Subsequent addition of propranolol almost instantaneously reduces the intracellular cAMP concentration, and thus the Na permeability, to their basal values (Mahé et al., 1985). If glutaraldehyde (0.06-0.1%) is added when the Na+/H+ exchanger is activated after hormonal stimulation, addition of propranolol no longer inhibits Na permeability: once activated and fixed by glutaraldehyde, the cAMP dependence disappears. Glutaraldehyde alone causes a rapid decrease in the cellular cAMP concentration. In its fixed state the antiporter is fully amiloride sensitive. The switching on of the Na+/H+ exchange by cAMP is rapidly (2 min) followed by acute but progressive desensitization of the exchanger (Garcia-Romeu et al., 1988). The desensitization depends on the concentration of external sodium, being maximal at a normal Na concentration (145 mM) and nonexistent at a low Na concentration (20 mM). If glutaraldehyde is added after activation in nondesensitizing conditions (20 mM Na), transfer to a Na-rich medium induces only a very slight desensitization: thus the fixative can "freeze" the exchanger in the nondesensitizing conformation. NO3- inhibits the activity of the cAMP-dependent Na+/H+ antiporter of the trout red blood cell (Borgese et al., 1986). If glutaraldehyde is added when the cells are activated by cAMP in a chloride-containing medium, the activity of the exchanger is no longer inhibited when Cl- is replaced by NO3-. Conversely, after fixation in NO3- medium replacement of NO3- by Cl- has very little stimulatory effect. This indicates that the anion dependence is not a specific requirement for the exchange process but that the anion environment is critical for the switching on of the Na+/H+ exchanger and for the maintenance of its activated configuration.