A Modular Trial of Androgen Signaling Inhibitor Combinations Testing a Risk-Adapted Strategy in Patients with Metastatic Castration-Resistant Prostate Cancer.

PURPOSE: To determine the efficacy and safety of risk-adapted combinations of androgen signaling inhibitors and inform disease classifiers for metastatic castration-resistant prostate cancers (mCRPC). EXPERIMENTAL DESIGN: In a modular, randomized phase II trial, 192 men were treated with 8 weeks of abiraterone acetate, prednisone and apalutamide (AAPA; Module 1), then allocated to Modules 2 or 3 based on Satisfactory (≥50% PSA decline from baseline and <5 CTC/7.5 mL) versus Unsatisfactory status. Men in the former were randomized to continue AAPA alone (Module 2A) or with ipilimumab (Module 2B). Men in the latter had carboplatin+cabazitaxel added to AAPA (Module 3). Optional baseline biopsies were subject to correlative studies. RESULTS: Median overall survival (from allocation) was 46.4 (95% CI 39.2, 68.2), 41.4 (95% CI 33.3, 49.9) and 18.7 (95% CI 14.3, 26.3) months in Modules 2A (n=64), 2B (n=64) and 3 (n=59) respectively. Toxicities were within expectations. Of 192 eligible patients, 154 (80.2%) underwent pre-treatment metastatic biopsies. The aggressive variant prostate cancer molecular profile (defects in ≥2 of p53, RB1, and PTEN) was associated with Unsatisfactory status. Exploratory analyses suggested SPP1+ and IGFBP2+ macrophages, druggable myeloid cell markers, and germline pathogenic mutations were enriched in the Unsatisfactory group. CONCLUSIONS: Adding ipilimumab to AAPA did not improve outcomes in men with androgen responsive mCRPC. Despite the addition of carboplatin+cabazitaxel, men in the Unsatisfactory group had shortened survivals. Adaptive designs can enrich for biologically and clinically relevant disease subgroups, to contribute to the development of marker-informed, risk-adapted therapy strategies in men with prostate cancer.

A Phase Ib/II Study of Ivosidenib with Venetoclax ± Azacitidine in IDH1-Mutated Myeloid Malignancies.

The safety and efficacy of combining the isocitrate dehydrogenase-1 (IDH1) inhibitor ivosidenib (IVO) with the BCL2 inhibitor venetoclax (VEN; IVO + VEN) ± azacitidine (AZA; IVO + VEN + AZA) were evaluated in four cohorts of patients with IDH1-mutated myeloid malignancies (n = 31). Most (91%) adverse events were grade 1 or 2. The maximal tolerated dose was not reached. Composite complete remission with IVO + VEN + AZA versus IVO + VEN was 90% versus 83%. Among measurable residual disease (MRD)-evaluable patients (N = 16), 63% attained MRD--negative remissions; IDH1 mutation clearance occurred in 64% of patients receiving ≥5 treatment cycles (N = 14). Median event-free survival and overall survival were 36 [94% CI, 23-not reached (NR)] and 42 (95% CI, 42-NR) months. Patients with signaling gene mutations appeared to particularly benefit from the triplet regimen. Longitudinal single-cell proteogenomic analyses linked cooccurring mutations, antiapoptotic protein expression, and cell maturation to therapeutic sensitivity of IDH1-mutated clones. No IDH isoform switching or second-site IDH1 mutations were observed, indicating combination therapy may overcome established resistance pathways to single-agent IVO. SIGNIFICANCE: IVO + VEN + AZA is safe and active in patients with IDH1-mutated myeloid malignancies. Combination therapy appears to overcome resistance mechanisms observed with single-agent IDH-inhibitor use, with high MRD-negative remission rates. Single-cell DNA ± protein and time-of-flight mass-cytometry analysis revealed complex resistance mechanisms at relapse, highlighting key pathways for future therapeutic intervention. This article is highlighted in the In This Issue feature, p. 247.

Immune and pathologic responses in patients with localized prostate cancer who received daratumumab (anti-CD38) or edicotinib (CSF-1R inhibitor).

BACKGROUND: The prostate tumor microenvironment (TME) is immunosuppressive, with few effector T cells and enrichment of inhibitory immune populations, leading to limited responses to treatments such as immune checkpoint therapies (ICTs). The immune composition of the prostate TME differs across soft tissue and bone, the most common site of treatment-refractory metastasis. Understanding immunosuppressive mechanisms specific to prostate TMEs will enable rational immunotherapy strategies to generate effective antitumor immune responses. Daratumumab (anti-CD38 antibody) and edicotinib (colony-stimulating factor-1 receptor (CSF-1R) inhibitor) may alter the balance within the prostate TME to promote antitumor immune responses. HYPOTHESIS: Daratumumab or edicotinib will be safe and will alter the immune TME, leading to antitumor responses in localized prostate cancer. PATIENTS AND METHODS: In this presurgical study, patients with localized prostate cancer received 4 weekly doses of daratumumab or 4 weeks of daily edicotinib prior to radical prostatectomy (RP). Treated and untreated control (Gleason score ≥8 in prostate biopsy) prostatectomy specimens and patient-matched pre- and post-treatment peripheral blood mononuclear cells (PBMCs) and bone marrow samples were evaluated. The primary endpoint was incidence of adverse events (AEs). The secondary endpoint was pathologic complete remission (pCR) rate. RESULTS: Twenty-five patients were treated (daratumumab, n=15; edicotinib, n=10). All patients underwent RP without delays. Grade 3 treatment-related AEs with daratumumab occurred in 3 patients (12%), and no ≥grade 3 treatment-related AEs occurred with edicotinib. No changes in serum prostate-specific antigen (PSA) levels or pCRs were observed. Daratumumab led to a decreased frequency of CD38+ T cells, natural killer cells, and myeloid cells in prostate tumors, bone marrow, and PBMCs. There were no consistent changes in CSF-1R+ immune cells in prostate, bone marrow, or PBMCs with edicotinib. Neither treatment induced T cell infiltration into the prostate TME. CONCLUSIONS: Daratumumab and edicotinib treatment was safe and well-tolerated in patients with localized prostate cancer but did not induce pCRs. Decreases in CD38+ immune cells were observed in prostate tumors, bone marrow, and PBMCs with daratumumab, but changes in CSF-1R+ immune cells were not consistently observed with edicotinib. Neither myeloid-targeted agent alone was sufficient to generate antitumor responses in prostate cancer; thus, combinations with agents to induce T cell infiltration (eg, ICTs) will be needed to overcome the immunosuppressive prostate TME.

Prognosis Associated With CA19-9 Response Dynamics and Normalization During Neoadjuvant Therapy in Resected Pancreatic Adenocarcinoma.

OBJECTIVE: To characterize associations between carbohydrate antigen 19-9 (CA19-9) dynamics during neoadjuvant therapy (NT) and survival for patients with pancreatic ductal adenocarcinoma (PDAC). BACKGROUND: Although normalization of CA19-9 during NT is associated with improved outcomes following PDAC resection, we hypothesize that CA19-9 dynamics during NT can improve prognostication. METHODS: Characteristics for patients with PDAC undergoing NT (July 2011-October 2018) with ≥3 CA19-9 results (bilirubin<2mg/dL) were collected and grouped by CA19-9 dynamics. Nonproducers (<1 U/ml) were excluded, and normal was ≤35 U/ml. Postresection survival was compared among groups. RESULTS: Of 431 patients, 166 had eligible CA19-9 values. Median baseline CA19-9 was 98 U/ml. Overall 2-year postresection recurrence-free survival (RFS) and overall survival (OS) were 37% and 63%, respectively. Patients with normalization (53%) had improved 2-year RFS (47% vs. 28%, P = 0.01) and OS (75% vs. 49%, P = 0.01). CA19-9 dynamics during NT were analyzed by shape, direction, and normalization creating response types ("A-B-C-D-E"). Type A was "Always" decreasing to normalization, B "Bidirectional" with eventual normalization, C "Consistently" normal, D any "Decrease" without normalization, and E "Elevating" without normalization. Types A and B responses were associated with the longest postresection 2-year RFS (51% and 56%) and OS (75% and 92%, respectively) whereas Types D and E had the worst outcomes. After adjusting for node-positivity, perineural invasion, and margin-positivity, CA19-9 response types were independently associated with both RFS and OS, and predicted outcomes are better than CA19-9 normalization alone (likelihood ratio test RFS P < 0.001, OS P = 0.01). CONCLUSIONS: This novel A-B-C-D-E classification of CA19-9 dynamics during NT was associated with postresection outcomes more precisely than CA19-9 normalization alone.

Genotype-to-Phenotype Associations in the Aggressive Variant Prostate Cancer Molecular Profile (AVPC-m) Components.

The aggressive variant prostate cancer molecular profile (AVPC-m), composed of combined defects in TP53, RB1 and PTEN, characterizes a subset of prostate cancers linked to androgen indifference and platinum sensitivity. To contribute to the optimization of the AVPC-m assessment for inclusion in prospective clinical trials, we investigated the status of the AVPC-m components in 28 patient tumor-derived xenografts (PDXs) developed at MDACC. We subjected single formalin-fixed, paraffin-embedded (FFPE) blocks from each PDX to immunohistochemistry (IHC), targeted next-generation genomic sequencing (NGS) and Clariom-S Affymetrix human microarray expression profiling. Standard validated IHC assays and a 10% labeling index cutoff resulted in high reproducibility across three separate laboratories and three independent readers for all tumor suppressors, as well as strong correlations with loss-of-function transcriptional scores (LOF-TS). Adding intensity assessment to labeling indices strengthened the association between IHC results and LOF-TS for TP53 and RB1, but not for PTEN. For TP53, genomic alterations determined by NGS had slightly higher agreement scores with LOF-TS than aberrant IHC, while for RB1 and PTEN, NGS and IHC determinations resulted in similar agreement scores with LOF-TS. Nonetheless, our results indicate that the AVPC-m components can be assessed reproducibly by IHC using various widely available standardized assays.

Increasing referral of at-risk women for genetic counseling and BRCA testing using a screening tool in a community breast imaging center.

BACKGROUND: Genetic evaluation and testing for hereditary breast and ovarian cancer (HBOC) remain suboptimal. The authors evaluated the feasibility of using a screening tool at a breast imaging center to increase HBOC assessment referrals. METHODS: A brief questionnaire based on the National Comprehensive Cancer Network HBOC genetic counseling referral guidelines was developed and added to the standard intake forms of patients undergoing mammography at a community breast imaging center from 2012 through 2015. Patients who met the criteria in the guidelines were referred for genetic counseling. RESULTS: A total of 34,851 patients were screened during the study period, and 1246 (4%) patients were found to be eligible for referral; 245 of these patients made a genetic counseling appointment, and 142 patients received genetic counseling. Forty patients (28%) had a personal history of breast cancer but were not previously tested. Following counseling, 105 patients were tested for BRCA1/2. Eight patients (8%) tested positive for a pathogenic mutation and nine (9%) had a variant of unknown significance. Although they tested negative, many patients met the criteria to add breast magnetic resonance imaging to their screening due to greater than 20% lifetime breast cancer risk based on their family cancer history. This study led to improved clinical risk management in 67% of the patients who underwent genetic counseling. CONCLUSIONS: This study shows that large-scale screening of patients for HBOC syndromes at time of breast imaging is practical and highly feasible. The screening tool identified women with actionable BRCA1/2 mutations and mutation-negative but high-risk women, leading to significant changes in their risk management; these women would otherwise have been missed. LAY SUMMARY: Hereditary breast and ovarian cancer (HBOC) caused by pathogenic mutations in breast cancer genes (BRCA1/BRCA2) increase an individual's lifetime risk of getting HBOC. Identifying these high-risk individuals and using proven preventive clinical risk management strategies can significantly reduce their lifetime risk of HBOC. Using an innovative family cancer history questionnaire, 34,000 women were screened at a community breast imaging center, and genetic counseling and testing were provided to eligible women from the screening. Several women at high risk for HBOC were identified and this led to positive clinical risk management changes. These women would have been missed if not for intervention.

Lessons Learned From Implementing a Novel Bayesian Adaptive Dose-Finding Design in Advanced Pancreatic Cancer.

PURPOSE: Novel Bayesian adaptive designs provide an effective way to improve clinical trial efficiency. These designs are superior to conventional methods, but implementing them can be challenging. The aim of this article was to describe what we learned while applying a novel Bayesian phase I-II design in a recent trial. METHODS: The primary goal of the trial was to optimize radiation therapy (RT) dose among three levels (low, standard, and high), given either with placebo (P) or an investigational agent (A), for treating locally advanced, radiation-naive pancreatic cancer, deemed appropriate for RT rather than surgery. Up to 48 patients were randomly assigned fairly between RT plus P and RT plus A, with RT dose-finding done within each arm using the late-onset efficacy-toxicity design on the basis of two coprimary end points, tumor response and dose-limiting toxicity, both evaluated at up to 90 days. The random assignment was blinded, but within each arm, unblinded RT doses were chosen adaptively using software developed within the institution. RESULTS: Implementing the design involved double-blind balance-restricted random assignment, real-time assessment of patient outcomes to evaluate the efficacy-toxicity trade-off for each RT dose in each arm to optimize each patient's RT dose adaptively, and transition from a single-center trial to a multicenter trial. We present lessons learned and illustrative documentation. CONCLUSION: Implementing novel Bayesian adaptive trial designs requires close collaborations between physicians, pharmacists, statisticians, data managers, and sponsors. The process is difficult but manageable and essential for efficient trial conduct. Close collaboration during trial conduct is a key component of any trial that includes real-time adaptive decision rules.

Combined CTLA-4 and PD-L1 blockade in patients with chemotherapy-naïve metastatic castration-resistant prostate cancer is associated with increased myeloid and neutrophil immune subsets in the bone microenvironment.

BACKGROUND: Immune checkpoint therapy (ICT) has low response rates in patients with metastatic castration-resistant prostate cancer (mCRPC), in part due to few T cells in the tumor microenvironment (TME). Anti-cytotoxic T lymphocyte-associated protein 4 (CTLA-4) promotes intratumoral T cell infiltration but induces upregulation of PD-1 and programmed death ligand-1 (PD-L1) within the prostate TME. Combined anti-CTLA-4 plus anti-PD-1 can partly overcome this adaptive resistance and was recently shown to augment responses in patients with mCRPC with measurable disease. Although bone is the most common site of metastasis in prostate cancer, patients with bone-predominant disease are frequently excluded from trials because they lack measurable disease, which limits assessment of disease progression and tissue sampling. We therefore designed this study to investigate combined ICT in mCRPC to bone. HYPOTHESIS: Combined anti-CTLA-4 (tremelimumab) plus anti-PD-L1 (durvalumab) is safe and well tolerated in patients with chemotherapy-naïve mCRPC to bone. PATIENTS AND METHODS: In this single-arm pilot study, men with chemotherapy-naïve mCRPC to bone received tremelimumab (75 mg intravenous) plus durvalumab (1500 mg intravenous) every 4 weeks (up to four doses), followed by durvalumab (1500 mg intravenous) maintenance every 4 weeks (up to nine doses). The primary endpoint was incidence of adverse events. Secondary endpoints included serum prostate-specific antigen (PSA), progression-free survival (PFS), radiographic PFS (rPFS), and maximal PSA decline. RESULTS: Twenty-six patients were treated between August 8, 2017 and March 28, 2019. Grade ≥3 treatment-related adverse events (TRAEs) occurred in 11 patients (42%), with no grade 4 or 5 events. TRAEs leading to discontinuation occurred in three patients (12%). PSA decline ≥50% occurred in three patients (12%). Six patients (24%) achieved stable disease for >6 months. At a median follow-up of 43.6 months, median rPFS was 3.7 months (95% CI: 1.9 to 5.7), and median overall survival was 28.1 months (95% CI: 14.5 to 37.3). Post-treatment evaluation of the bone microenvironment revealed transcriptional upregulation in myeloid and neutrophil immune subset signatures and increased expression of inhibitory immune checkpoints. CONCLUSIONS: Tremelimumab plus durvalumab was safe and well tolerated in patients with chemotherapy-naïve mCRPC to bone, with potential activity in a small number of patients as measured by rPFS. Combination of CTLA-4 and PD-L1 blockade with therapies targeting the myeloid compartment or other inhibitory immune receptors may be necessary to overcome mechanisms of resistance within prostate bone microenvironment. TRIAL REGISTRATION NUMBER: NCT03204812.

Venetoclax plus intensive chemotherapy with cladribine, idarubicin, and cytarabine in patients with newly diagnosed acute myeloid leukaemia or high-risk myelodysplastic syndrome: a cohort from a single-centre, single-arm, phase 2 trial.

BACKGROUND: Addition of the BCL2 inhibitor venetoclax to lower intensity therapy has been shown to improve overall survival in older (aged 75 years or older) and unfit patients with newly diagnosed acute myeloid leukaemia. The aim of this study was to investigate the activity of venetoclax combined with intensive chemotherapy in patients aged 65 years or younger with acute myeloid leukaemia. METHODS: This cohort study was done at the MD Anderson Cancer Center in the USA, as part of the single-centre, single arm, phase 2, CLIA trial. Here we report on the independent cohort investigating the safety and activity of venetoclax added to intensive chemotherapy (the CLIA regimen [cladribine, high-dose cytarabine, idarubicin]). Eligible patients were aged 18-65 years with a new diagnosis of acute myeloid leukaemia, mixed phenotype acute leukaemia, or high-risk myelodysplastic syndrome (≥10% blasts or International Prognostic Scoring System ≥2 [intermediate]), who received no previous potentially curative therapy for leukaemia. Patients received cladribine (5 mg/m2) and cytarabine (1·5 g/m2 for patients aged <60 years, 1 g/m2 for patients aged ≥60 years) intravenously on days 1-5 and idarubicin (10 mg/m2) intravenously on days 1-3. Consolidation was cladribine (5 mg/m2) and cytarabine (1 g/m2 for patients aged <60 years and 0·75 g/m2 for patients aged ≥60 years) on days 1-3 and idarubicin (8 mg/m2) on days 1-2. Venetoclax (400 mg) was given on days 2-8 with each course. Patients with a known FLT3-ITD or FLT3-TKD mutation received midostaurin or gilteritinib. The primary outcome was composite complete response (complete response plus complete response with incomplete blood count recovery). Secondary outcomes were overall response, duration of response, event-free survival, overall survival, and safety. This trial was registered with ClinicalTrials.gov, NCT02115295. FINDINGS: Between Feb 25, 2019, and March 23, 2021, 77 patients were assessed for eligibility, 50 of whom were enrolled. Median age was 48 years (IQR 37-56). 47 (94% [95% CI 83-98]) patients had composite complete response, with the same proportion also having an overall response; two (4% [1-14]) patients did not respond, and one (2% [0-11]) patient died during induction. 37 (82% [95% CI 68-92]) of 45 patients had undetectable measurable residual disease (MRD). At a median follow-up of 13·5 months (IQR 6·4-19·5), the median duration of response, event-free survival, and overall survival were not reached. At 12 months, the estimated duration of response was 74% (95% CI 60-92), event-free survival was 68% (54-85), and overall survival was 85% (75-97). The most common adverse events of grade 3 or worse were febrile neutropenia (42 [84%] patients), infection (six [12%]), and alanine aminotransferase elevations (six [12%]). There was one death during induction in a patient treated with CLIA-venetoclax plus a FLT3 inhibitor. Two patients died of infectious complications while in complete response in consolidation cycles, both of whom had FLT3-mutated acute myeloid leukaemia and were receiving combined therapy with a FLT3 inhibitor. No deaths were deemed to be treatment related. INTERPRETATION: Venetoclax added to CLIA was safe and active in patients with newly diagnosed acute myeloid leukaemia or high-risk myelodysplastic syndrome, producing high rates of durable MRD-negative remissions and encouraging event-free survival and overall survival. FUNDING: MD Anderson Cancer Center.

A heavy metal baseline score predicts outcome in acute myeloid leukemia.

Despite abundant epidemiological data linking metals to leukemia and other cancers, baseline values of toxic and essential metals in patients with leukemia and the clinical impact of these metals remain unknown. Thus, we sought to quantify metal values in untreated patients with acute myeloid leukemia (AML) and controls and determine the impact of metal values on AML patients' survival. Serum samples from patients with untreated AML and controls at Hospices Civils de Lyon were analyzed and compared for trace metals and copper isotopic abundance ratios with inductively coupled plasma mass spectrometry. Survival analysis was performed as a function of metal values, and a multi-metal score was developed for patients with AML. Serum samples were collected from 67 patients with untreated AML and 94 controls. Most patients had intermediate-risk cytogenetics (63.1%) without FLT3 internal tandem duplication mutations (75.6%) or NPM1 mutations (68.1%). Most metal values differed significantly between AML and control groups. Patients with lower magnesium and higher cadmium values had the worst survival rates, with only 36% surviving at 6 months (P = .001). The adverse prognostic effect of this combination was maintained on multivariate analysis. Based on this, we developed a novel metal score, which accounts for multiple relative abnormalities in the values of five toxic and five essential metals. Patients with a higher metal score had significantly worse survival, which was maintained on multivariate analysis (P = .03). This baseline metal scoring system was also prognostic when we applied it to a separate population of front-line AML patients.

Autoimmune antibodies correlate with immune checkpoint therapy-induced toxicities.

Immune checkpoint (IC) therapy provides substantial benefits to cancer patients but can also cause distinctive toxicities termed immune-related adverse events (irAEs). Biomarkers to predict toxicities will be necessary to improve management of patients receiving IC therapy. We relied on serological analysis of recombinant cDNA expression libraries to evaluate plasma samples from patients treated with IC therapy and identified autoantibodies, both in pretreatment and on-treatment samples prior to the development of irAEs, which correlate with the development of immune-related hypophysitis (anti-GNAL and anti-ITM2B autoantibodies) and pneumonitis (anti-CD74 autoantibody). We developed an enzyme-linked immunosorbent assay and tested additional patient samples to confirm our initial findings. Collectively, our data suggest that autoantibodies may correlate with irAEs related to IC therapy, and specific autoantibodies may be detected early for the management of irAEs.

Phase II Study of Carfilzomib in Patients With Refractory Renal Cell Carcinoma.

BACKGROUND: A von Hippel Lindau (VHL) mutation or functional inactivation occurs in the a large proportion of patients with clear-cell renal cell carcinoma (ccRCC), which results in the dysregulation of a number of key cellular functions. A high throughput screen and candidate compound assessment revealed that agents with proteasome inhibition properties were able to stabilize point-mutated VHL and restore some of its functions. PATIENTS AND METHODS: Nine patients with histologically confirmed metastatic ccRCC with disease progression during at least 1 previous systemic therapy were treated with carfilzomib at a dose of 20 mg/m2 over 30 minutes via intravenous (I.V.) infusion on days 1 and 2 and a dose of 56 mg/m2 over 30 minutes via I.V. infusion on days 8, 9, 15, and 16 of each 4-week cycle. RESULTS: The study was stopped after 9 patients were enrolled because of futility. Of the 9 patients treated in the study, all patients had disease progression within 4 months, with a median time of 1.8 months (95% confidence interval, 0.8-3.6 months). No patient showed a response according to Response Evaluation Criteria In Solid Tumors. Three patients showed a best response of stable disease. The most common side effects were musculoskeletal pain, elevated creatinine level, anemia, hyperkalemia, leukopenia, lymphopenia, and fatigue. CONCLUSION: Although the negative safety and efficacy results of this study do not favor the use of carfilzomib for the treatment of ccRCC, previous studies have shown selected patients achieved partial or complete response to this class of agent. Further preclinical investigations to evaluate the molecular characteristics of the patients who respond to proteasome inhibitors will better characterize the underlying mechanism of response, and might allow for the selection of an appropriate patient population in future studies.

Potential Influence on Clinical Trials of Long-Term Survivors of Stage IV Non-small cell Lung Cancer.

BACKGROUND: New, effective treatments have resulted in long-term survival for small subgroups of metastatic non-small cell lung cancer (NSCLC) patients. However, knowledge of long-term survivor frequency and characteristics prior to modern therapies is lacking. METHODS: Surveillance Epidemiology and End Results (SEER) patients with stage IV NSCLC diagnosed from 1991 to 2007 and followed through 2012 were dichotomized by survival time into the 10% who lived 21 months or longer (long-term survivors) vs the remaining 90% and compared with participants in a representative clinical trial of molecular profiling and targeted therapies (CUSTOM). RESULTS: Among the 44 387 SEER patients, the 10% identified as long-term survivors were distinguishable from the remaining 90% by younger age, female sex, Asian race, adenocarcinoma histology, tumor grade, tumor site, and surgery. From 1991-1994 to 2003-2007, median survival increased by 6 months from 30 to 36 months among long-term survivors but by only 1 month from 3 to 4 months among the remaining 90%. Among the 165 participants in the CUSTOM trial, 54% met our SEER criterion of long-term survival by living for 21 months or longer. CONCLUSIONS: Among SEER patients with stage IV NSCLC, long-term survivors had a median survival approximately 10 times that of the remaining 90%. Long-term survivors accounted for more than one-half of the participants in a representative clinical trial. Caution is required when extrapolating the outcomes of participants in clinical trials to patients in routine clinical practice.