Post-protocol therapies in first-line immunotherapy trials in non–small cell lung cancer (NSCLC)

125

Background: The advent of immunotherapy (IO) has led to significant improvement in outcomes for patients (pts) with advanced non-small cell lung cancer (adv NSCLC). The rate of crossovers and receipt of post-protocol IO in pivotal trials leading to FDA approvals of IO in NSCLC has not been systematically evaluated. Here, we evaluate crossover rates and post protocol therapies for pts with adv NSCLC across multiple first-line (1L) IO monotherapy and chemotherapy/IO (chemo/IO) combination trials. Methods: We utilized the publicly available data from pivotal clinical trials leading to approvals of IO or chemo/IO regimens in 1L treatment of adv NSCLC. We extracted data on outcomes, rate of crossover from control arm to IO, proportion of pts in control arm receiving IO and the start dates of these clinical trials. The primary outcomes were the rates of crossover and the proportion of patients in control arms who received post-control IO. Results: The study included 4 trials with IO monotherapy and 12 trials with chemo/IO combinations in 1L adv NSCLC. The primary endpoints for these trials were PFS (25%), OS (19%), and both PFS and OS (56%). The crossover rate from control arm to experimental arm (with IO) ranged from 0-74% in IO monotherapy trials and 0-49% in chemo/IO trials. Two IO monotherapy trials and five chemo/IO trials did not allow crossover; among them, 3 trials had a PFS/OS co-primary endpoint, while others had OS as primary endpoint. Ten of 16 trials provided explicit information on use of subsequent post-protocol therapies in their publications. Among the two IO monotherapy trials which did not allow crossover, post-protocol IO was administered in only 20-30% of patients. Among the six chemo/IO trials with information on post-protocol therapies, 30%-59% patients on the control arm subsequently received some form of IO on progression. Nine of 12 trials started accrual after 10/2015, when nivolumab was approved in the United States as second-line (2L) therapy for adv NSCLC regardless of tumor PD-L1 expression. Conclusions: Despite the highly significant OS benefit from 2L IO, which was the standard of care (SOC) in the United States, the rates of crossover and post-protocol IO administration was distressingly low in 1L IO monotherapy and chemo/IO trials for 1L adv NSCLC. This low rate of 2L treatment with IO may have been due to limited global availability prior to widespread regulatory approval during the conduct of these trials. There is an increased need for consistency in reporting of crossover treatment and post-protocol treatments to allow adequate assessment of the true 1L benefit with IO. Control arms in pivotal trials require scrutiny to ensure confirmation with SOC to provide access to optimal treatments for patients and prevent magnification of observed benefits in experimental arms. The difficulty lies in the global conduct of large randomized clinical trials with differing regulatory approvals.

Efficacy of immune checkpoint inhibitors in non-small cell lung cancer: A systematic review and meta-analysis

Background

Immune checkpoint inhibitors (ICIs) have demonstrated remarkable efficacy in non-small cell lung cancer (NSCLC). However, only a minority of NSCLC patients benefit from ICIs, and whether the magnitude of benefit is specific factor-dependent remains unclear. We performed a systematic review to improve our understanding of clinicopathologic and biomolecular features associated with improved survival upon treatment with ICIs for NSCLC.

Methods

We searched PubMed, Web of Science, Embase, and Scopus from database inception to August 31, 2021, for randomized controlled trials (RCTs) comparing overall survival (OS) in NSCLC treated with ICIs vs control therapies. We calculated the pooled OS hazard ratio (HR) and 95% CI in subgroups using a random-effects model, and assessed the heterogeneity between the paired estimates using an interaction test.

Results

A total of 23 RCTs involving 15,829 patients were included. We found that wild-type EGFR, high PD-L1 expression, and high bTMB were associated with a significant OS benefit from ICIs, but not mutant EGFR, low PD-L1 expression, and low bTMB. The differences of OS benefit between wild-type and mutant EGFR (HR=1.53, 95%CI 1.13-2.08), high and low PD-L1 (HR=1.35; 95%CI 1.14-1.61), high and low bTMB (HR=1.71; 95%CI 1.17-2.52) were statistically significant. OS benefit was found in all subgroups regardless of sex, age, ECOG PS, histology, smoking history, baseline brain metastasis, race, and region, and the interaction test demonstrated no significant difference of the OS benefit between these opposed subgroups (e.g. male vs female).

Conclusions

Wild-type EGFR, high PD-L1 expression, and high bTMB are associated with a greater magnitude of efficacy from ICIs vs control therapies in NSCLC. However, the administration of ICIs should not be restricted to other clinicopathological factors (sex, smoking history, race, etc.).

Phase 2 randomized trial of neoadjuvant or palliative chemotherapy with or without immunotherapy for peritoneal mesothelioma (Alliance A092001)

TPS8598

Background: Peritoneal mesothelioma is a rare and poorly studied disease with few treatment options. For patients who are not surgical candidates, treatment recommendations for systemic therapy have been extrapolated from clinical trials for pleural mesothelioma that commonly exclude patients with peritoneal mesothelioma. Recently, the combination of the PD-1 inhibitor nivolumab and the CTLA-4 inhibitor ipilimumab received FDA-approval for the frontline treatment of non-resectable pleural mesothelioma. Additionally, a prospective, non-randomized phase 2 trial demonstrated activity with combined PD-L1 (atezolizumab) and VEGF (bevacizumab) blockade in peritoneal mesothelioma. In parallel, encouraging activity with combined chemo-immunotherapy has been reported in pleural mesothelioma. Given the benefits observed with immunotherapy, and the potential to improve upon those with chemotherapy and VEGF inhibition, we seek to determine whether the addition of the PD-L1 inhibitor atezolizumab improves outcomes with chemotherapy and bevacizumab in patients with newly diagnosed peritoneal mesothelioma. Methods: A092001 is a prospective, randomized phase 2 clinical trial. All patients with newly diagnosed peritoneal mesothelioma will be randomized 1:1 using a dynamic allocation Pocock-Simon procedure to receive carboplatin, pemetrexed, and bevacizumab, with or without atezolizumab, every 21 days for four cycles. Patients who are eligible to proceed with surgery after four cycles of therapy will then do so. Patients who are not eligible to proceed with surgery may receive maintenance bevacizumab and atezolizumab, or second-line atezolizumab with bevacizumab until progression of disease or toxicity. The primary objective is to determine whether frontline treatment with carboplatin, pemetrexed, bevacizumab and atezolizumab results in a superior best response rate (RR) to carboplatin, pemetrexed and bevacizumab as determined by RECIST. With 31 eligible patients per arm (62 eligible total), this randomized design has 80% power to detect an improvement in the RR from 20% to 45%, with a 1-sided significance level of 0.10 where an interim futility analysis will be conducted after 32 patients are enrolled. As stratification factors we have included eligibility for cytoreductive surgery at diagnosis, and histologic subtype. Secondary endpoints include assessment of progression-free survival, overall survival, and adverse events. As integrated biomarkers, we will determine if soluble mesothelin-related peptides and megakaryocyte potentiating factor correlate with responses. This trial was recently approved by the National Cancer Institute Central IRB and is activating at sites across the country. Support: U10CA180821, U10CA180882. Clinical trial information: NCT05001880.

Pralsetinib in patients (pts) with advanced or metastatic RET-altered thyroid cancer (TC): Updated data from the ARROW trial

6080

Background: Alterations in RET are targetable oncogenic drivers in TC. Pralsetinib is a highly potent, selective RET inhibitor, with demonstrated efficacy in pts with RET-altered TC. In a previous analysis of the Phase I/II ARROW trial (NCT03037385; data cutoff: 22 May 2020), overall response rates [ORR; measurable-disease population] with pralsetinib at 400 mg once daily (QD) were 60% (33/55) and 71% (15/21) in pts with RET-mutant medullary TC ( RET-mutant MTC) who had received prior multikinase inhibitors cabozantinib and/or vandetanib (C/V), and those who were treatment naïve, respectively, and 89% (8/9) in pts with previously treated RET fusion-positive TC ( RET-fp TC). Here we report an updated analysis of these cohorts in the intention-to-treat (ITT) population. Methods: Adult pts with RET-altered locally advanced/metastatic TC who had enrolled in ARROW and initiated pralsetinib at 400 mg QD, were included. Phase II primary endpoints: ORR (by blinded independent central review, per RECIST v1.1) and safety. Efficacy endpoints for this analysis were assessed in the ITT population. Safety was assessed in all pts with RET-altered TC who initiated pralsetinib at 400 mg QD. Enrolment cutoff: 23 August 2020 for the ITT population; data cutoff: 12 April 2021. Results: The ITT population comprised 145 pts with RET-mutant MTC (with or without prior systemic therapy, including C/V) and 22 pts with RET-fp TC, 21 of whom had received prior systemic therapy (including multikinase inhibitor[s] and/or radioactive iodine). In pts with RET-mutant MTC who had received prior C/V (n = 67), ORR was 51% (34/67; 95% CI 38–63; 2 complete responses [CR]; 32 partial responses [PR]), median duration of response (DoR) was 25.8 months (95% CI 18.0–not reached [NR]) and median progression-free survival (PFS) was 24.9 months (95% CI 19.7–31.2). In treatment-naïve pts with RET-mutant MTC, ORR was 72% (48/67; 95% CI 59–82; 4 CR; 44 PR), and median DoR and median PFS were not reached. In pts with previously treated RET-fp TC, ORR was 86% (18/21; 95% CI 64–97; 3 CR; 15 PR), median DoR was 17.5 months (95% CI 16.0–NR) and median PFS was 19.4 months (95% CI 13.0–NR). Median overall survival (OS) was not reached in any of the cohorts. The safety population comprised 172 pts with RET-altered TC treated at 400 mg QD. The most common treatment-related adverse events (TRAEs) were increased aspartate aminotransferase (n = 67; 39%), anemia (n = 60; 35%), hypertension (n = 57; 33%) and decreased white blood cell count (n = 52; 30%). Serious TRAEs were reported in 27 pts (16%); the most frequent was pneumonitis (n = 5; 3%). Nine pts (5%) discontinued pralsetinib due to a TRAE and one patient ( < 1%) died due to a TRAE ( pneumocystis jirovecii pneumonia) following 44 days ( < 3 cycles) on pralsetinib. Conclusions: In this updated analysis including more pts, pralsetinib continues to be efficacious with a manageable safety profile in pts with RET-altered TC. Clinical trial information: NCT03037385.

Amivantamab in patients with NSCLC with MET exon 14 skipping mutation: Updated results from the CHRYSALIS study

9008

Background: Amivantamab, a fully human bispecific antibody targeting epidermal growth factor receptor (EGFR) and MET, is approved for the treatment of non-small cell lung cancer (NSCLC) with EGFR exon 20 insertion after prior platinum-based chemotherapy. Given its bispecific nature, amivantamab is being explored in patients (pts) with primary MET exon 14 skipping mutation (METex14) in the MET-2 cohort of the CHRYSALIS study. Methods: CHRYSALIS (NCT02609776) is an ongoing phase 1 dose escalation/dose expansion study of amivantamab in pts with advanced NSCLC. Pts with primary METex14 whose disease progressed on or who declined current standard of care therapy were treated with amivantamab 1050 mg (pts <80 kg) or 1400 mg (pts ≥80 kg) weekly in cycle 1 and biweekly thereafter. Response was assessed by investigators using RECIST v1.1. Results: As of 2 Dec 2021, 43 pts with METex14 had received amivantamab. Median age was 70 y (range, 43-88), 58% were women, median prior lines of therapy was 2 (range, 0-10) [eg, crizotinib (n=13), capmatinib (n=11), tepotinib (n=5), anti-MET antibody (n=1)], and 23% had history of brain metastases at baseline. In 36 pts with ≥1 postbaseline disease assessment, median duration of follow-up was 5.8 months (range, 0.3-15.8); 6 pts had no prior treatment, 11 had no prior MET inhibitor, and 19 had a prior MET inhibitor. Overall response rate was 33% (50% [3/6] in treatment-naïve pts, 46% [5/11] in pts with no prior MET inhibitor, and 21% [4/19] in pts with prior MET inhibitor therapy). Clinical benefit rate was >54% regardless of prior treatment (Table). Median duration of response (DOR) was not reached (range, 2.1-12.2 months); 67% (8/13) had DOR ≥6 months. Ten of the 12 responders remain on treatment (6.0-14.4 months) with ongoing responses; 2 discontinued after 2 and 12 months, respectively. Safety profile was consistent with previously reported experience of amivantamab (Sabari 2021 JTO 16(3):S108-109). Treatment-related adverse events leading to dose reduction or discontinuation occurred in 3 pts, each. Conclusions: Amivantamab demonstrates anti-tumor activity in primary METex14 NSCLC including after prior MET inhibitor treatment. Enrollment is ongoing and updated data will be shown. Clinical trial information: NCT02609776. [Table: see text]

MC1923 phase II clinical trial of durvalumab (MEDI4736) and topotecan or lurbinectedin in patients with relapsed extensive-stage small cell lung cancer previously treated with chemotherapy and immunotherapy

TPS8604

Background: Chemoimmunotherapy followed by durvalumab maintenance yields a median overall survival of 12.9 months in patients with extensive stage Small Cell Lung Cancer (ES SCLC), which is an improvement over chemotherapy alone. However, 90% of these patients will have progressive disease. While topotecan and lurbinectedin have established modest activity in the second line, it is unknown whether continuing immunotherapy in this setting confers additional benefit. In preclinical studies lurbinectedin, a DNA minor groove binder, used with immune checkpoint inhibitors has synergistic effects. Methods: This phase 2 trial is enrolling patients with ES SCLC who have progressed on platinum based chemoimmunotherapy, to three treatment groups. Group 1 includes patients with platinum sensitive SCLC who will receive durvalumab (1500 mg given as an intravenous [IV] infusion once every 3 weeks) and topotecan (1.25 mg/m2/day IV for 5 consecutive days every 3 weeks). In Groups 2A and 2B, patients with platinum sensitive and platinum resistant disease respectively, receive durvalumab and lurbinectedin (3.2 mg/m2 IV on Day 1 of every 21-day cycle). Patients with platinum sensitive disease are assigned to Groups 1 or 2A based on the preferences of the treating physician and the patient. Patients with treated/stable CNS metastases are eligible. The primary endpoint is the proportion of patients who are alive at 6 months (6OS) for Group 1 and the proportion of patients who are alive and progression-free at 6 months (6PFS) in Groups 2A and 2B. Secondary endpoints include safety, adverse event profile, response rate, PFS, and OS. The sample size is based on a 2-stage Simon Optimal Design. For Treatment Group 1, with 22 eligible patients there is 80% power to detect a true 6-month OS rate (6OS) of 75%, with 10% alpha under the null hypothesis that the true 6OS is at most 50%. For Treatment Group 2A, with 20 eligible patients this design has 80% power to detect a true 6-month PFS rate (6PFS) of 65%, with 10% alpha under the null hypothesis that the true 6PFS is at most 40%. For Treatment Group 2B, with 22 eligible patients this design has 80% power to detect a true 6-month PFS rate (6PFS) of 40%, with 10% alpha under the null hypothesis that the true 6PFS is at most 19%. To account for possible drop-outs, accrual targets will be 24, 22, and 24 patients to Groups 1, 2A, and 2B respectively. For the safety analyses, 6 patients will be enrolled at the starting dose level for each treatment group (1, 2) and then briefly closed to accrual to assess adverse events. If we observe 2+ DLTs in these 6 treated patients during Cycle 1 within a treatment group (1 vs. 2), we will declare the combination treatment too toxic and lower the starting dose of chemotherapy for the next 6 patients. The study was open for all 3 groups as of January 2022 and has accrued 2 patients. Clinical trial information: NCT04607954.

The use of artificial intelligence with uncertainty estimation to predict lung cancer relapse from histopathology

8549

Background: First-line treatment of early stage non-small cell lung cancer (NSCLC) is surgical resection, but with a 5-year survival of only 54%, rates of future relapse are high. Identifying patients at high risk of relapse can help guide adjuvant treatment decisions. Deep convolutional neural network (DCNN) AI models trained on tumor histology have shown incredible flexibility as potential biomarkers, both in lung cancer and more generally across many malignancies. While DCNN models can obtain extremely accurate results when used for routine purposes such as diagnosis, subtyping, and grading of malignancies, most models trained for prognostication or treatment response prediction do not reach performance sufficient for clinical application. Uncertainty quantification (UQ) – a family of techniques that give DCNN models the ability to report confidence alongside predictions – is an underexplored avenue in cancer AI that may help further improve performance and clinical application of models designed to provide clinicians with estimations of risk. Methods: To explore the potential use of UQ in clinically-oriented DCNN models, we trained models on a single-institution, retrospective digital tumor histology slide cohort from patients with Stage I-III NSCLC who underwent surgical resection to predict risk of future relapse. Estimation of uncertainty was performed using dropout as a Bayesian approximation, and uncertainty thresholds were calculated from training sets using a novel method to identify and remove low-confidence predictions. For comparison, a separate multivariate logistic regression was trained in cross-validation using known clinical risk factors. Results: We trained DCNN models on slides from 198 patients (40 relapsed, 158 without relapse). In this cohort, 130 patients had stage I disease (65.6%), 42 had stage II (21.2%), and 26 had stage III (13.2%). The average age was 69 years, 85% were current or previous smokers, and 38 received guideline-concordant adjuvant chemotherapy. Without UQ, a DCNN model predicted risk of future relapse with an average area under receiver operator curve (AUROC) of 0.74 across three-fold cross-validation. Using UQ estimation, 63% of slides were reported with high confidence. Relapse prediction was significantly improved in the high-confidence cohort, with an average AUROC of 0.83 in cross-validation. With a specificity of 70%, this corresponds to an average sensitivity of 86.8% across the three cross-folds (79.1%, 85.5%, and 95.7%). In comparison, a clinical-only multivariate regression model predicted relapse with a cross-validated AUROC of 0.67. Conclusions: This method of uncertainty quantification appears to be a powerful tool to predict lung cancer recurrence risk from digital histopathology while simultaneously providing clinicians with a measurement of algorithm trustworthiness.

Genomic predictors of benefit from checkpoint inhibition in neuroendocrine carcinoma

512

Background: The role of immune checkpoint inhibitors (ICIs) in the treatment of extrapulmonary neuroendocrine carcinoma (EP-NEC) has yet to be established. While objective responses have been observed, it is still unknown which patients are likely to derive benefit. We investigated the genomic profiles of patients who did and did not benefit from ICIs. Methods: Previously we reported the objective responses to ICI in a retrospective series of patients with EP-NEC. RECIST 1.1 criteria were used to categorize patients as achieving disease control (DC = CR, PR, or SD) vs progressive disease (PD). The EMR was reviewed to identify patients who had genomic panels performed, and results were extracted for analysis. Results: Of 31 patients eligible for RECIST assessment, 19 had genomic panels available (9 with DC: 4 SD, 5 PR vs 10 with PD). Of those with NEC histology specified, 9 were small cell, 1 combined large and small cell, 3 were large cell. All tumors were microsatellite-stable. All but one (with TMB = 25) of 16 tumors with TMB status available were < 10 m/MB. Of those with disease control, 67% had both TP53 and RB1 alterations, compared with only 10% in those with progressive disease; this was statistically significant ( p = 0.0198, Fisher exact). Of 7 tumors with TP53 + RB1 alterations, 4 were specified as small cell carcinoma. Half of those with PD showed alterations in β-catenin pathway genes CTNNB1 or APC, compared to only one of the DC group, but this did not reach significance ( p = 0.1409, Fisher exact). In an analysis of all Mayo patients (not just those treated with ICI) with NGS data available (Tempus and FoundationOne), concurrent TP53 + RB1 alteration was significantly more common in SCLC than in EP-NEC (Table). Conclusions: In this small series of patients with EP-NEC treated with ICIs, the SCLC-like genomic signature of concurrent TP53 + RB1 alterations was significantly more common in those with disease control than in those with progressive disease. An analysis of all patients with NGS data (not just on ICI) showed that the dual alteration was more common in SCLC, and SCLC also had more TMB-high tumors. This may explain why ICIs are more effective in SCLC than in EP-NEC. Further study is warranted to determine whether TP53 + RB1 mutations predict response to ICI in NEC.[Table: see text]

Chemoimmunotherapy for the treatment of extensive-stage small cell lung cancer (ES-SCLC) in patients with an Eastern Cooperative Group (ECOG) performance status (PS) of two or greater

8569

Background: Immune checkpoint inhibitor (atezolizumab or durvalumab) combined with platinum-etoposide is the standard first-line therapy for patients with extensive-stage small cell lung cancer (ES-SCLC). The phase III clinical trials that led to the approval of chemoimmunotherapy in ES-SCLC, excluded patients with an Eastern Cooperative Group (ECOG) Performance Status (PS) of Two or Greater. Therefore, data on efficacy of this combination in this subgroup of ES-SCLC patients whose performance status two or greater is limited. Methods: A retrospective analysis was performed of patients diagnosed with ES-SCLC who received chemoimmunotherapy (atezolizumab or durvalumab) within the Mayo Clinic Health System between January 2016 and January 2021. Cases were identified from clinical databases at Mayo Clinic. Data on demographics, ECOG-PS, date of diagnosis, date of progression, whole brain radiation, CNS involvement, liver involvement, stereotactic body radiation, chest consolidation, platinum sensitivity, lines of therapy and last follow up date were extracted. Overall Survival (OS) and progression free survival (PFS) for ECOG-PS 2-3 were compared to patients with an ECOG-PS 0-1. Results: A total of 84 patients were identified with a median age of 68.2 (48-88) years old. Of these, 54 patients were identified with an ECOG-PS 0-1 and 30 patients with an ECOG-PS 2-3. The median PFS for the ECOG PS 0-1 cohort was 5.2 months (95% CI 4.6-6.1) while the median PFS for the ECOG-PS 2-3 cohort was 6.0 months (95% CI 4.2-7.7; logrank p = 0.93). The median OS for the ECOG-PS 0-1 cohort was 10.8 months (95% CI 8.5-12.9) while the median OS for the ECOG-PS 2-3 cohort was 10.3 months (95% CI 6.0-14.1; logrank p = 0.39). Hazard ratios of ECOG-PS 0-1 versus 2-3 showed no tendency of increased PFS or OS for either group within cox proportional hazards models. Forty-three percent of ECOG-PS 0-1 achieved a partial response (PR) and 57% of patients who had ECOG-PS 2-3 also achieved a PR (Fisher’s exact p = 0.23). A complete response was found in 4% of ECOG-PS 0-1 compared to 3% in the ECOG-PS 2-3 cohort. For patients who responded to initial therapy, 46% of ECOG-PS 2-3 patients had a platinum sensitive relapse while only 33% of ECOG-PS 0-1 were still platinum sensitive at the time of relapse. Five ECOG-PS 2-3 patients were able to receive a second-line therapy. Conclusions: To our knowledge, this is the first study to evaluate chemoimmunotherapy in the subgroup of ES-SCLC patients with an ECOG-PS 2 or greater. This retrospective study demonstrated no significant difference in PFS, OS, and ability to achieve a least a PR in ECOG-PS 2-3 cohort when compared to ECOG-PS 0-1. Therefore, chemoimmunotherapy should not be reserved for only an ECOG-PS of 0-1 but should be considered for all treatment eligible patients.

Single institution toxicity of definitive chemoradiation and maintenance durvalumab in locally advanced non-small cell lung cancer

e20554

Background: The paradigm for locally advanced non-small cell lung cancer has been markedly altered to include maintenance durvalumab (D) post completion of definitive chemoradiation (CRT) following the publication of the Pacific trial in 2018. The toxicity of this treatment has not been well evaluated in the real-world setting. Methods: We identified 42 patients (pts) with Stage IIB-IIIC NSCLC treated at Mayo Clinic Rochester between 6/1/2018 and 10/1/2020 who received definitive CRT followed by maintenance D. Data were abstracted by retrospective chart review under an IRB approved protocol. Results: Median age was 66 yrs (range 47-90) and 62% were women. Primary lung cancer histology included 19 adenocarcinoma, 20 squamous cell, and 3 adenosquamous. The distribution of stages was: IIB (4/42), IIIA (15/42), IIIB (19/42), IIIC (4/42). Approximately half of patients had PDL1 expression > 25% (20/42). With a median follow up of 12.2 months (calculated from first cycle of D; range 4.2-30.5 months), 14 had completed one year of maintenance D, 16 were receiving ongoing D, and 10 stopped D early with 6/12 discontinuing due to disease progression (4/6 local progression, 2/6 distant progression). Other reasons for discontinuation (5/10) included grade 3 colitis, grade 2 hepatitis, aspergillus lung infection, and flare of autoimmune disorders. One quarter of patients experienced grade 2 radiation pneumonitis (RP; 10/42) with median time to development of RP 78 days from end of CRT and 45 days from start of D. RP was determined by multidisciplinary review of imaging and treatment fields. 17/42 patients developed immune related adverse events (see Table for details). There was minimal overlap between the patients who experienced pneumonitis and immune related toxicity; 2/17 had both pneumonitis and immune related toxicity (hepatitis, thyroiditis). Conclusions: In our early experience with the Pacific regimen, 29% of patients did not complete D due to either toxicity or progression during D administration. Pneumonitis was common (10/42 patients) although there were no grade 3 events. Nearly half of the patients developed an immune-related adverse event. Further analysis is needed to evaluate the real-world toxicity of this treatment as well as oncologic outcomes.[Table: see text]

Safety and efficacy of pralsetinib in patients with advanced RET fusion-positive non-small cell lung cancer: Update from the ARROW trial

9089

Background: RET fusions are targetable oncogenic drivers in 1–2% of non-small cell lung cancer (NSCLC). ARROW (NCT03037385) supported the US FDA approval of pralsetinib, a highly potent oral selective RET inhibitor for RET-altered NSCLC and thyroid cancer. Here, we present updated results for a larger population of patients with RET fusion–positive NSCLC enrolled in ARROW. Methods: ARROW is a phase 1/2 open-label study conducted at 84 sites in 13 countries. Phase 2 expansion cohorts included patients with RET fusion–positive NSCLC. Initially, all treatment-naïve patients were not candidates for platinum-based therapy, a requirement removed by protocol amendment in July 2019. Primary objectives are overall response rate (ORR; blinded independent central review [BICR] per RECIST v1.1), assessed for patients with baseline measurable disease, and safety. Results: Updated analyses were completed as of Nov 6, 2020 (data cut-off), for patients who initiated pralsetinib 400 mg QD by May 22, 2020 (enrollment cut-off). Efficacy results, including analyses for treatment-naïve patients enrolled after eligibility criteria were revised to allow candidates for platinum-based therapy, are shown in the Table. Conclusions: Pralsetinib showed rapid, potent, and durable clinical activity in patients with RET fusion-positive NSCLC (regardless of prior therapies), including poor prognosis patients not eligible for platinum-based therapy. Overall, pralsetinib was well-tolerated. These data highlight the need for RET testing early in the course of disease to identify candidates who may benefit from treatment with pralsetinib. Clinical trial information: NCT03037385. [Table: see text]

Clinical activity of the RET inhibitor pralsetinib (BLU-667) in patients with RET fusion–positive solid tumors

467

Background: Recent tumor-agnostic drug approvals have resulted in a paradigm shift in cancer treatment away from organ/histology specific indications to biomarker-guided tumor-agnostic approaches. Pralsetinib is a potent and selective RET inhibitor, which has recently been approved by the U.S. Food and Drug Administration (FDA) for the treatment of adults with metastatic RET fusion–positive non-small cell lung cancer (NSCLC) and is under New Drug Application review for RET mutant thyroid cancers by the FDA. RET fusions occur in up to approximately 7‒8% of patients with gastrointestinal malignancies, including pancreatic, liver, and colorectal cancers. There are currently no approved selective RET inhibitors for patients with RET fusion–positive solid tumors other than NSCLC and thyroid cancer. Here, we present data on the clinical activity of pralsetinib in patients with RET fusion–positive solid tumor types other than NSCLC enrolled in the Phase I/II ARROW study (NCT03037385). Methods: ARROW consists of a phase I dose escalation (30–600 mg once [QD] or twice daily) followed by a phase II expansion (400 mg QD) in patients with advanced RET-altered solid tumors. Primary objectives are overall response rate (ORR), per RECICT v1.1 and safety. Results: A total of 13 patients with RET fusion–positive thyroid cancer (12 papillary, 1 poorly differentiated; enrollment cutoff July 11, 2019) and 14 patients with RET fusion–positive solid tumors other than NSCLC and thyroid (3 pancreatic, 3 colon, 2 cholangiocarcinoma, 6 other; enrollment cutoff November 19, 2019) were enrolled in ARROW and received pralsetinib. At the February 13, 2020, data cutoff, the ORR (blinded central review) in response-evaluable patients with RET fusion–positive thyroid cancer was 91% (10/11; 95% CI: 59‒100) and disease control rate was 100% (95% CI: 72‒100). Treatment was ongoing in 7 of 11 patients. In RET fusion–positive solid tumors other than NSCLC and thyroid, ORR (investigator’s assessment) was 50% (6/12; 95% CI: 21‒79) and responses were observed in all patients with pancreatic cancer (3/3) and cholangiocarcinoma (2/2). Treatment was ongoing in 6 of 12 patients, including 2 of 3 patients with pancreatic cancer and 1 of 2 patients with cholangiocarcinoma. Responses were observed across multiple fusion genotypes. In the 27 patients with RET fusion–positive tumors other than NSCLC, most frequent treatment-related adverse events (TRAEs) were grade 1–2, and included anemia (33%), increased aspartate aminotransferase (33%), decreased white blood cell count (33%), hypertension (30%), increased alanine aminotransferase (26%), hyperphosphatemia (19%), and neutropenia (19%). No patients discontinued due to TRAEs. Conclusions: Pralsetinib demonstrated broad and durable antitumor activity across multiple advanced solid tumor types, regardless of RET fusion genotype, and was well tolerated. The study is ongoing. Clinical trial information: NCT03037385.

Utilization Trends and Factors Associated With ROS1 Testing Among Patients With Advanced Non-small-cell Lung Cancer in US Community Practices

BACKGROUND

Targeted therapy for patients with non-small-cell lung cancer (NSCLC) harboring ROS proto-oncogene 1 (ROS1) rearrangements was approved in 2016. However, little is known about real-world ROS1 testing practices in United States community practice. We aimed to characterize ROS1 testing rates and identify potential barriers to ROS1 testing.

PATIENTS AND METHODS

Flatiron Health's de-identified electronic health record-derived database was used to identify patients diagnosed with advanced NSCLC from July 2016 through December 2018 who received systemic treatment in a community practice setting. ROS1 and other biomarker testing was recorded. Regression analysis identified demographic and clinical characteristics associated with occurrence of ROS1 testing, longer time (≥ 25 days) from diagnosis to ROS1 result, and initiation of therapy prior to ROS1 result.

RESULTS

Among 11,409 patients, documented ROS1 testing rates increased during the study period in squamous (from 30% to 48%) and nonsquamous (63% to 78%) histologies. Patients who were older, male, black, or with squamous histology, higher Eastern Cooperative Oncology Group score, recurrent disease, or history of smoking were significantly less likely to be tested. Among patients not tested for ROS1, 63% were tested for other biomarkers. Use of next-generation sequencing, older age, Hispanic/Latino ethnicity, squamous histology, de novo disease, and smoking history predicted longer time to test result post-diagnosis. Patients with delayed results were 9.7 times more likely to receive treatment prior to ROS1 test result.

CONCLUSION

In real-world practice, some patient subgroups may be less likely to receive timely ROS1 testing and to be identified for potential targeted therapy.

Interim subgroup analysis for response by PD-L1 status of CLASSICAL-Lung, a phase Ib/II study of pepinemab (VX15/2503) in combination with avelumab in advanced NSCLC

3011

Background: Antibody blockade of semaphorin 4D (SEMA4D, CD100) promotes tumoral dendritic cell and CD8+ T cell infiltration and reduces function and recruitment of immunosuppressive myeloid cells. Importantly, these mechanisms to overcome immune exclusion and suppression have been shown to complement immune checkpoint therapies in preclinical models. Pepinemab is an IgG4 humanized monoclonal antibody targeting semaphorin 4D. The CLASSICAL-Lung clinical trial tests the combination of pepinemab with avelumab to couple T cell activation via checkpoint inhibition with beneficial modifications of the immune microenvironment via pepinemab. Methods: This phase 1b/2, single arm, first-in-human study is designed to evaluate the safety, tolerability and efficacy of pepinemab with avelumab in 62 patients (pts) with advanced (stage IIIB/IV) non-small cell lung cancer (NSCLC), including immunotherapy-naïve (ION) pts and pts whose tumors progressed following immunotherapy (IOF). Results: Among 21 evaluable ION pts, 5 experienced partial response (PR), 3 pts had clinical benefit ≥ 1 year, and the disease control rate (DCR) is 81%. Pts enrolled in this study were observed to have lower PD-L1 expression relative to prior single agent studies (likely due to approval of pembrolizumab for first line therapy). We, therefore, performed subgroup analysis for response by PD-L1 status. The objective tumor response (ORR) in the PD-L1 negative and low population ( < 80% TPS by Dako 73-10 assay) appears to be approximately 2-2.5 fold greater with combination therapy than with historical single agent immune checkpoint controls. Notably, 97% of pts who experienced PR or SD were reported to have tumors with negative or low PD-L1 expression. Among 29 evaluable IOF pts, the combination resulted in 59% DCR, including 2 PR and 7 patients with durable clinical benefit of ≥ 23 weeks. Biomarker analysis of pre- and on-treatment biopsies confirmed increased CD8+ T cell density correlating with response. Surprisingly, analysis of myeloid-derived suppressor cells (MDSCs) revealed a relative paucity of these cells in pretreatment NSCLC biopsies as compared to other cancer indications such as HNSCC. Conclusions: This trial is nearing completion with only 5 of 62 subjects remaining on study. Preliminary data suggest the combination is well tolerated and shows signs of increased antitumor activity, particularly in PD-L1 negative or low tumors. Updated clinical response data and immunophenotypic analyses will be presented. Clinical trial information: NCT03268057 .

Capmatinib in patients with METex14-mutated or high-level MET-amplified advanced non–small-cell lung cancer (NSCLC): results from cohort 6 of the phase 2 GEOMETRY mono-1 study

9520

Background: Capmatinib (INC280) has shown promising efficacy in patients (pts) with MET exon 14 ( METex14)–mutated NSCLC who were pretreated (cohort 4) or treatment (tx)-naïve (cohort 5b) in the ongoing, multicohort, phase 2 GEOMETRY mono-1 study. We report the results for pts enrolled in the expansion cohort 6 with either high-level MET amplification (gene copy number [GCN] ≥10) or METex14 mutation (any MET GCN) whose disease progressed on 1 prior line of systemic therapy. Methods: Adult pts (≥18 years), ECOG PS 0–1 who had ALK and EGFR wt, stage IIIB/IV NSCLC (any histology) received capmatinib tablets 400 mg twice daily (with or without food). Key efficacy endpoints were overall response rate (ORR) and duration of response (DOR) by blinded independent review committee (BIRC) per RECIST v1.1. Other secondary endpoints included investigator-assessed ORR, DOR, disease control rate (DCR), progression-free survival (PFS; BIRC and investigator assessment) and safety. Results: As of Jan 6, 2020, 34 NSCLC pts with METex14 mutation (n = 31) or high-level MET amplification (n = 3) were included in this analysis. Tx was ongoing for 38.2% of pts. In METex14-mutated NSCLC pts, per BIRC assessment: ORR was 48.4%, median DOR was 6.93 months (mo, not yet mature, 95% CI: 4.17–NE) and median PFS was 8.11 mo (not yet mature, 95% CI: 4.17–9.86). Investigator-assessed responses were similar to BIRC assessment (Table). Only 3 pts with high-level MET amplification were included in this cohort due to challenges in enrollment. All 3 pts had stable disease per BIRC assessment and were on treatment for 48, 85 and 97 days. Most common AEs (≥25%, all grades, N = 34) were peripheral edema (64.7%), nausea (35.3%), fatigue (29.4%), back pain (26.5%) and vomiting (26.5%). Data for pts with brain metastasis will be presented at the ASCO 2020 meeting. Conclusions: Capmatinib was confirmed to be efficacious in 2nd line, METex14-mutated NSCLC pts. This is the first cohort where capmatinib has been administered without fasting restriction and data confirm the favorable safety profile. Clinical trial information: NCT02414139 . [Table: see text]

Clinical activity of the RET inhibitor pralsetinib (BLU-667) in patients with RET fusion+ solid tumors

109

Background: RET gene fusions are targetable oncogenic drivers in multiple tumor types, including up to 20% of papillary thyroid cancers (PTC). Pralsetinib is an investigational, highly potent, selective inhibitor of oncogenic RET alterations. In the registration-enabling Phase 1/2 ARROW study (NCT03037385), pralsetinib demonstrated an overall response rate (ORR; response-evaluable patients [REP], central review) of 73% (19/26) in treatment-naïve patients and 61% (49/80; 2 pending confirmation) in platinum-exposed patients with RET fusion+ non-small cell lung cancer (NSCLC) and was well tolerated (data cut-off November 18, 2019). We provide an update on the clinical activity of pralsetinib in other RET fusion+ solid tumor types. Methods: ARROW consists of a phase 1 dose escalation (30–600 mg once [QD] or twice daily) followed by a phase 2 expansion (400 mg QD) in patients with advanced RET-altered solid tumors. Primary objectives were ORR and safety. Results: As of November 18, 2019, 29 patients with metastatic solid tumor types other than NSCLC (16 PTC, 1 undifferentiated thyroid, 3 pancreatic, 3 colon, 6 other) bearing a RET fusion have received pralsetinib. Efficacy data are presented for REP enrolled by July 11, 2019. In patients with thyroid cancer that is RET fusion+, ORR (investigator assessment) was 75% (9/12; all confirmed). Median (range) duration of response (DOR) was 14.5 (3.7+, 16.8) months (mo), with 67% of responding patients continuing treatment. Two patients with stable disease were continuing treatment at 11.5+ and 19.3+ mo. In other RET fusion+ cancers, ORR was 60% (3/5; all confirmed) with partial responses in 2/2 patients with pancreatic cancer (DOR 5.5, 7.4+ mo) and 1 patient with intrahepatic bile duct carcinoma (DOR 7.5 mo). Two patients with colon cancer had stable disease for 7.3 and 9.3 mo. Responses were observed across multiple fusion genotypes. In the entire safety population (all patients treated with 400 mg QD pralsetinib, regardless of diagnosis; n = 354), most treatment-related adverse events (TRAEs) were grade 1-2, and included increased aspartate aminotransferase (31%), anemia (22%), increased alanine aminotransferase (21%), constipation (21%) and hypertension (20%). Only 4% of patients in the safety population discontinued due to TRAEs. Conclusions: Pralsetinib demonstrated broad and durable antitumor activity across multiple advanced solid tumor types, regardless of RET fusion genotype, and was well tolerated. The study is ongoing and still enrolling patients in this cohort. Clinical trial information: NCT03037385.

A phase I/II study of rovalpituzumab tesirine in delta-like 3-expressing, advanced solid tumors

3552

Background: Delta-like 3 (DLL3) is highly and specifically expressed in solid tumors, such as neuroendocrine carcinomas (NECs), malignant melanoma (MM), and medullary thyroid carcinoma (MTC). Rovalpituzumab tesirine (Rova-T) is a DLL3-targeting antibody-drug conjugate. Methods: This Phase 1/2 study (NCT02709889) enrolled patients with relapsed/refractory DLL3+ (>1% by IHC) advanced solid tumors and ECOG performance status of 0-1. Rova-T was given IV at 0.2, 0.3, or 0.4 mg/kg on d 1 of each 6-wk cycle (q6wk) for dose escalation (3+3 design) in disease-specific cohorts in Phase I. The recommended Phase 2 dose (RP2D) was tested in Phase II. Safety and dose-limiting toxicities (DLTs) were primary endpoints; efficacy outcomes were secondary endpoints. Results: The study enrolled 200 patients; 101 had NECs (large cell NEC [n=13], neuroendocrine prostate cancer [n=21], high-grade gastroenteropancreatic NEC [n=36], other [n=31]) and 99 had other solid tumors (MM [n=20], MTC [n=13], glioblastoma [GBM; n=23], other [n=43]). The median age was 61 y (range, 28-84); 63% were male. The RP2D was 0.3 mg/kg q6wk for 2 cycles in all cohorts. There were 7 DLTs in 5 patients: 2 with 0.2 mg/kg (Grade [Gr] 3 photosensitivity reaction, Gr 3 dyspnea), 2 with 0.3 mg/kg (1 with Gr 2 effusion, Gr 3 tumor lysis syndrome, and Gr 3 rhabdomyolysis; 1 with Gr 4 kidney injury), and 1 with 0.4 mg/kg (Gr 4 thrombocytopenia). Despite only 1 DLT identified with 0.4 mg/kg, the totality of the safety data suggested that this dose is not well tolerated. Common adverse events (AEs) in patients given 0.3 mg/kg (n=145) are shown (Table). Serious AEs occurred in 77/145 patients (53%), most commonly (≥3%) malignant neoplasm progression (n=18; 12%), pleural effusion (n=7; 5%), pericardial effusion (n=6; 4%), and dyspnea (n=5; 3%). The objective response rate (ORR) was 11% (21/200): 14 had NEC, 2 had MM, 2 had MTC, 2 had small cell carcinoma (SCC) not of lung origin (all partial responses), and 1 had GBM (complete response). In patients with NECs given 0.3 mg/kg, ORR, clinical benefit rate, and progression-free survival trended in favor of those with high DLL3-expressing tumors (≥50% by IHC) which represented 51% of NECs. Conclusions: Rova-T was tolerable in patients with advanced solid tumors at 0.3 mg/kg q6wk for 2 cycles. Antitumor activity was observed in patients with NEC, MM, MTC, SCC, and GBM. Clinical trial information: NCT02709889 . [Table: see text]

Impact of delaying initiation of anaplastic lymphoma kinase inhibitor treatment on survival in patients with advanced non-small-cell lung cancer

INTRODUCTION

Several obstacles may delay receipt of targeted treatment in patients with anaplastic lymphoma kinase positive (ALK+) non-small-cell lung cancer (NSCLC). This study examined the factors associated with delayed initiation of ALK inhibitor (ALKi) treatment and its impact on overall survival (OS) as well as the impact of initiating chemotherapy before biomarker test results.

MATERIALS AND METHODS

Advanced NSCLC (aNSCLC) patients selected from the deidentified Flatiron Health electronic health record-derived database were stratified into early- and delayed-use cohorts based on initiation of ALKi treatment relative to time since receiving ALK+ biomarker test results; cohorts were further stratified by timing of chemotherapy initiation relative to availability of ALK+ test results. Prescription-time matching (PTM) was used to examine the effect of delayed ALKi treatment and chemotherapy on survival; Cox proportional hazards models adjusting for baseline characteristics before and after PTM were used to examine factors associated with delayed ALKi treatment and the effects of delayed ALKi treatment and chemotherapy on OS, respectively.

RESULTS

Comparison of OS between early- and delayed-use cohorts (N = 442 ALK + aNSCLC patients) demonstrated that a >3-week delay in the initiation of ALKi treatment was associated with a >2-fold higher risk of death (adjusted hazard ratio [HR] [95 % CI] 2.05 [1.13, 3.71]. The number of office visits, age factors, and use of chemotherapy were associated with an increased risk of being untreated >3 weeks after ALK+ test results. There were no significant differences in survival outcomes regardless of whether patients received chemotherapy before the ALK+ test result or ALKi treatment (adjusted HR [95 % CI] 1.02 [0.64, 1.63]). Completing the chemotherapy regimen after receiving ALK+ test results did not appear to improve survival (adjusted HR [95 % CI] 0.84 [0.38, 1.9]).

CONCLUSION

Initiating ALKi treatment for aNSCLC patients in a timely manner may have a positive impact on survival outcomes.

Human leukocyte antigen expression in paired primary lung lesions and brain metastases in non-small cell lung cancer

43

Background: Human leukocyte antigens (HLA) are crucial for cytotoxic T cell responses to cancer. Loss of HLA expression is a mechanism of tumor immune escape and may contribute to resistance to immunotherapy. In patients with non-small cell lung cancer (NSCLC) treated with immune checkpoint inhibitors we have observed discordant responses between brain metastases and extracranial disease and reported on differential PD-L1 expression and clonal T cell infiltration between paired primary lung lesions and brain metastases. In this project we sought to evaluate whether HLA expression was retained in metastatic NSCLC. Methods: Adult patients with paired primary NSCLC and brain metastases were identified from our institution’s tissue registry. HLA-A cell membrane expression on tumor cells was determined by immunohistochemistry with an anti-HLA-A antibody. Tumors with greater than 10% HLA expression were considered positive. Agreement statistics (κ) and Fisher’s exact test were used for analysis. Results: 51 patients with paired primary NSCLC and brain lesions were identified. The median HLA expression was 20% in the primary tumors (IQR 0-65%) and 10% in the brain metastases (IQR 5-40%). 27 primary tumors and 24 brain metastases were positive for HLA expression. There was disagreement in HLA positivity between paired lesions in 11 patients (22%, 95% CI 12-35%)(κ = 0.57, 95% CI 0.35-0.79)(p = 0.0001). There was no significant difference in the time between the primary tumor and brain metastasis resections in patients with HLA expression disagreement compared to those with HLA expression agreement. None of the patients received immune checkpoint inhibitors for treatment of these lesions. Conclusions: We found significant differences in HLA-A expression on tumor cells in nearly one quarter of paired primary lung cancers and brain metastases. Differences in HLA expression may help explain the discrepancies in response to immune checkpoint inhibitors at different sites of disease and warrants further study.

Interim results from a phase Ib/II study of pepinemab in combination with avelumab in advanced NSCLC patients following progression on prior systemic and/or anti-PDx therapies

75

Background: Despite progress of immune checkpoint therapies, many cases of non-small cell lung cancer (NSCLC) are refractory or acquire resistance to current therapies. Antibody blockade of semaphorin 4D (SEMA4D, CD100) can overcome resistance mechanisms of immune exclusion and myeloid suppression. Importantly, combinations of anti-SEMA4D with various immunotherapies enhanced T cell infiltration and activity, as well as durable tumor regression in preclinical models. Pepinemab (VX15/2503) is a first-in-class humanized monoclonal antibody targeting SEMA4D. Methods: The CLASSICAL-Lung clinical trial (NCT03268057) evaluates the combination of pepinemab with anti-PD-L1 antibody avelumab to couple beneficial modifications of the immune microenvironment via pepinemab with immune activation via checkpoint inhibition. This ongoing study evaluates the safety, tolerability and efficacy of the combination in patients with advanced (stage IIIB/IV) NSCLC, including immunotherapy-naïve (ION) patients and patients whose tumors progressed during or following immunotherapy (IOF). Results: The combination was well tolerated with no major safety signals identified. Among 29 evaluable IOF patients, two experienced confirmed partial response (PR) with 63% and 52% tumor reduction on study following acquired resistance to prior treatment with pembrolizumab, 15 additional patients experienced stable disease, and at least 5 patients with durable clinical benefit of ≥ 23 weeks. Among 21 evaluable ION patients, 5 experienced PR, clinical benefit ≥ 1 year was observed in 3 patients, and Disease Control Rate was 81%. Analysis of pre- and on-treatment biopsies demonstrated increased CD8+ T cell density correlating with response, reduction or elimination of tumor in 11/13 biopsies from subjects with PR or SD. Conclusions: Interim analysis suggests the combination of pepinemab plus avelumab is well tolerated and shows initial clinical signals of antitumor activity. Updated clinical response data (minimum of 6 mo. follow-up), as well as additional immunophenotyping of both inflammatory and suppressive myeloid cells will be presented. Clinical trial information: NCT03268057.

Chromosomal rearrangements and their neoantigenic potential in mesothelioma

Chromosomal rearrangements are a defining molecular feature of mesothelioma that are not readily detected by standard DNA sequencing approaches but could be detected by whole genome sequencing methods such as mate-pair sequencing. These chromosomal rearrangements result in novel, unique gene junctions that can be expressed and potentially result in the presentation of several neoantigens. These predicted neoantigens can be presented by tumors on major histocompatibility complex (MHC) proteins and are correlated with clonal expansion of tumor infiltrating T cells. T cells responsive to these neoantigens have been identified in the circulation of a patient. The predictive values of next generation sequencing-based tumor mutation burden measurements may be significantly enhanced by the addition of techniques such as mate-pair sequencing that can detect chromosomal rearrangements. Furthermore, rearrangement associated neo-antigens may also represent valuable targets for future anti-tumor vaccine strategies. Finally, chromosomal rearrangements are now recognized as a mutation signature in cancer and these events are likely to be important in the oncogenesis and immune recognition of not only in mesothelioma but multiple malignancies including non-small cell lung cancer.

Safety and patient-reported outcomes of atezolizumab, carboplatin, and etoposide in extensive-stage small-cell lung cancer (IMpower133): a randomized phase I/III trial

BACKGROUND

The addition of atezolizumab to carboplatin and etoposide (CP/ET) significantly improved progression-free and overall survival for patients with extensive-stage small-cell lung cancer (ES-SCLC) in the IMpower133 study (NCT02763579). We have evaluated adverse events (AEs) and patient-reported outcomes in IMpower133 to assess the benefit-risk profile of this regimen.

PATIENTS AND METHODS

Patients received four 21-day cycles of CP/ET plus intravenous atezolizumab 1200 mg or placebo (induction phase), followed by atezolizumab or placebo (maintenance phase) until progression or loss of benefit. AEs were assessed and patient-reported outcomes were evaluated every 3 weeks during treatment using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire - Core 30 (QLQ-C30) and QLQ-LC13.

RESULTS

Overall, 394 patients were assessable for safety in the induction phase and 318 in the maintenance phase. The frequency of AEs, grade 3-4 AEs, and serious AEs was similar between arms in both phases. Immune-related AEs were more frequent in the atezolizumab arm during both induction (28% versus 17%; leading to atezolizumab/placebo interruption 9% versus 5%, leading to withdrawal 4% versus 0%) and maintenance (26% versus 15%; leading to atezolizumab/placebo interruption, 3% versus 2%, leading to withdrawal 1% versus 1%), most commonly rash (induction 11% versus 9%, maintenance 14% versus 4%), and hypothyroidism (induction 4.0% versus 0%, maintenance 10% versus 1%). Changes in patient-reported treatment-related symptoms commonly associated with quality of life impairment were generally similar during induction and most of the maintenance phase. Patient-reported function and health-related quality of life (HRQoL) improved in both arms after initiating treatment, with more pronounced and persistent HRQoL improvements in the atezolizumab arm.

CONCLUSIONS

In patients with ES-SCLC, atezolizumab plus CP/ET has a comparable safety profile to placebo plus CP/ET, and the addition of atezolizumab did not adversely impact patient-reported HRQoL. These data demonstrate the positive benefit-risk profile of first-line atezolizumab plus CP/ET in ES-SCLC and further support this regimen as a new standard of care in this setting.

CLINICAL TRIALS NUMBER

NCT02763579.

Small cell lung cancer: Sociodemographic factors in patients’ decisions for treatment

144

Background: Small cell lung cancer (SCLC) is highly responsive to cytotoxic therapy and can be cured in early stages of disease. In this setting, disparities in patient refusal despite provider recommendations are unknown. Methods: All incident limited stage (LS)-SCLC cases from the National Cancer Database were identified from 2004 to 2014. Logistic regression was used to determine factors associated with treatment refusal. Results: 65,664 patients (pts) were identified with LS-SCLC: 44% male, median age 68 years. 3.4% of pts refused radiation and 3.8% refused chemotherapy. The proportion of chemotherapy refusal increased over the study period: 3% in 2004-2006 compared to 5.4% in 2013-2014 [odds ratio (OR) 1.76, 95% confidence interval (CI) 1.55-2.01]; this was not observed for radiation. In multivariate analysis, women were more likely to refuse radiation (OR 1.18, 95% CI 1.06-1.32) and chemotherapy (OR 1.30, 95% CI 1.19-1.43) than men. Women who accepted treatment had higher overall survival compared to those who refused radiation (19.8 vs 5.2 months) or chemotherapy (17.4 vs 3.9 months) (both p < 0.001). Hispanic, Black, and Asian pts were not more likely to refuse treatment than White pts. Older pts were more likely to refuse radiation (OR 1.09 per year, 95% CI 1.08-1.09) and chemotherapy (OR 1.10 per year, 95% CI 1.09-1.11). Charlson comorbidity index (CCI) of 2 was associated with more frequent treatment refusal compared to CCI of 0 (radiation OR 1.96, 95% CI 1.68-2.30; chemotherapy OR 1.54, 95% CI 1.34-1.76). Medicaid as primary insurance predicted a higher risk of refusal compared to private insurance for radiation (OR 2.36, 95% CI 1.81-3.07) and chemotherapy (OR 2.23, 95% CI 1.78-2.80). Treatment at an academic facility predicted a lower risk of radiation refusal (OR 0.71, 95% CI 0.59-0.84) but not chemotherapy refusal. Conclusions: Female sex, comorbidities, and Medicaid insurance were predictors of treatment refusal in LS-SCLC, suggesting that socioeconomic and sex disparities may affect treatment decisions in this life-threatening disease. Further research to identify reasons for refusal via patient and provider interviews can improve care of vulnerable populations with potentially curable cancer.

Association of patient characteristics with real-world ROS1 NSCLC testing patterns among community practices in the United States

e18321

Background: Despite the availability of targeted therapy for ROS1 NSCLC since 2016, there is limited information on real-world ROS1 testing practices to identify patients potentially eligible for targeted treatment among community practices. The objective of this study was to characterize ROS1 testing rates and identify potential barriers to ROS1 testing. Methods: The Flatiron Health EHR-derived database was used to identify patients diagnosed with advanced NSCLC between 7/1/2016 - 7/30/2018 and received systemic treatment in a community practice setting. Descriptive statistics were used to summarize the population, biomarker testing rates and timing of testing. Logistic and multinomial regressions including patient demographics and clinical characteristics were used to identify factors associated with the following outcomes: ROS1 testing, testing for biomarkers other than ROS1 (PDL1, ALK, EGFR) , longer times from advanced diagnosis (adv. dx) to ROS1 test results and initiation of therapy prior to ROS1 testing. Results: Of 9,275 eligible patients, ROS1 testing rates in squamous (SQ) and non-squamous histologies increased over the study period (30% to 52%, 62% to 75% respectively). Older age, males, poorer performance status, SQ histology, history of smoking and recurrent disease (RD) patients were significantly less likely to be tested. Among patients not tested for ROS1, 62% were tested for other biomarkers including > 50% of non-squamous patients tested for PDL1, EGFR or ALK and 51% of squamous patients tested for PDL1. The median time from adv. dx to test result was 24 days, with patient characteristics (i.e. Hispanic ethnicity, history of smoking) as well as test type predicting longer times to test results ( > 41 days vs. < 24 days after adv. dx). Patients who had a delay in test results were more likely to receive other therapy prior to availability of their ROS1 test results (25+ days vs. < 24 days OR [95% CI]: 9.18 [7.87, 10.70]). Conclusions: In real-world practice, patient characteristics were associated with ROS1 testing and testing delays which may result in some patient subgroups being less likely to be identified for potential targeted therapy.

Low nationwide utilization of adjuvant chemotherapy (AC) in elderly patients with localized non-small cell lung cancer (NSCLC)

6581

Background: While AC is recommended for all patients with stage IIA, IIB, and IIIA NSCLC, its use and benefit among the elderly population is unclear. Methods: We identified patients with stage IIA, IIB, or IIIA NSCLC using the National Cancer Database from 2006-2014. Patients were divided into age groups ≤65, 66-70, 71-75, 76-80, > 80 years. Trends in AC use, factors influencing AC administration, and outcomes associated with AC were studied. Results: Out of 27368 patients, 13464 received AC and 13904 did not. 11% had stage IIA disease, 50% had stage IIB disease and 39% had stage IIIA disease. AC use was lower with increasing age (49% age ≤65 vs. 3% age > 80 (P < 0.0001)). Temporal use of chemotherapy for each age group was unchanged from 2006-2014. In multivariate logistic regression analysis, factors predictive of lower AC use were older age, Medicare or Medicaid insurance, academic center, and higher Charlson Comorbidity Index (CCI). Stage IIIA (OR 1.4, 95% CI 1.3-1.6) and Stage IIB (OR 1.3, 95% CI 1.2-1.4) had a higher chance of receiving AC than stage IIA. In a Cox proportional hazard model, younger age, female sex, academic center, private insurance, higher income, lower CCI, West coast center and AC were associated with better outcomes. When stratified by age and stage, AC was still associated with better survival (Table). Conclusions: AC utilization in stages IIA, IIB and IIIA NSCLC remains low, despite its association with improved survival in the elderly. Future clinical trials may be needed focused on elderly patients to establish the best regimen to optimize outcomes. [Table: see text]

Pooled subgroup analysis of twelve randomized controlled trials of immunotherapy in non-small cell lung cancer

e20639

Background: Multiple randomized controlled trials (RCTs) have shown a robust benefit of immunotherapy with immune checkpoint inhibitors (ICI) in non-small cell lung cancer (NSCLC). We did a meta-analysis to examine the benefit of ICI in various subgroups. Methods: PubMed was searched up to Jan 15, 2019 for RCTs comparing overall survival (OS) between ICI and control (without ICI) arms. Pooled hazard ratio (HR) and 95% confidence interval (CI) was calculated for each subgroup. Interaction tests were done to compare relative benefit between opposed subgroups of interest (eg. men vs women; reported as Pheterogeneity). All analyses were performed with a random effects model in Comprehensive Meta Analysis (v2). Results: Twelve phase 2/3 RCTs involving 7244 patients were included. A significant OS benefit of ICI was found in both squamous and non-squamous histology. Current/former smokers, EGFR wild-type, and KRAS mutant patients had a significant OS benefit from ICI, but never smokers, EGFR mutant, and KRAS wild-type patients did not. An OS benefit of ICI was found in patients with or without baseline brain metastasis, PD-L1 < 1% or ≥1%, men or women, age < 65 or ≥65, and ECOG PS 0 or ≥1. No significant difference of relative benefit from ICI over control was found in patients with different PD-L1 expression, sex, age, or ECOG PS (Table). Conclusions: OS benefit of ICI in NSCLC was associated with a smoking history, wild-type EGFR or KRAS mutation. However, the OS benefit of ICI was seen regardless of histology, PD-L1 expression, sex, age, and ECOG PS. [Table: see text]

Exploring sex differences in small cell lung cancer: Is this a hormonal issue?

e20077

Background: Small cell lung cancer (SCLC) accounts for about 10% to 15% of lung cancers among women and men. Though heavily associated with smoking, its incidence in women is rapidly increasing despite a decline in cigarette exposure. Given the changing demographics of SCLC and hormonal factors associated with other forms of lung cancer, we studied differences between sexes in SCLC. Methods: Utilizing the National Cancer Database, we identified all incident SCLC cases from 2004 to 2014. Patients were classified as limited stage (LS) or extensive stage (ES). Women were stratified by menopausal status (≥55 years = postmenopausal). Kaplan-Meier method and Cox regression were used for overall survival (OS) and multivariable analysis. Results: 161,978 patients were identified. No significant sociodemographic differences were observed between sexes. The majority of patients were non-Hispanic whites (89.1%), followed by non-Hispanic blacks (7.5%). Men were more likely to be diagnosed with ES disease than women (63% vs. 56%). Both sexes initiated treatment within a similar time frame from diagnosis (chemotherapy, median: 18 days, IQR 8-32). Women had better median OS compared to men in both LS (15.2 vs. 12.7 months, HR: 0.85, 95% CI 0.83-0.86, p < 0.0001) and ES (6.4 vs. 5.7 months, HR: 0.88, 95% CI 0.87-0.90, p < 0.0001). No racial or ethnic disparities in OS were observed, overall and when examined within sex and disease stage groups. Differences between sexes in OS were also observed when comparing patients within the same racial/ethnic group (women having better OS). When divided by menopausal status, postmenopausal women with LS and ES had worse OS than premenopausal women (14.7 vs. 22 months, HR: 1.50, 95% CI 1.44-1.56; 6.1 vs. 9.8 months, HR: 1.41, 95% CI: 1.37-1.46, respectively). We also observed worse OS in older men when divided by age ( < 55 years and ≥55 years). In multivariable analysis, older age, postmenopausal status, and Medicaid as primary insurance were associated with worse OS for both LS and ES. Conclusions: In this large cohort, women with SCLC had better OS compared to men. Post-menopausal women had worse OS compared to pre-menopausal women. Since older men had a similar trend of worse survival compared to younger men, age might exert a more significant influence on survival than hormonal status in SCLC. Further studies with data on sexual hormone levels are necessary to better understand their role in women with SCLC.

Is a delay in ALK inhibitor initiation associated with poorer survival? A retrospective analysis based on real-world data

e18240

Background: The time between a patient’s positive biomarker test result and initiation of targeted therapy may vary due to a number of factors, including the use of chemotherapy prior to or after the biomarker test result. The objective of this study was two-fold: first, to investigate the impact of delayed ALK inhibitor (ALKi) therapy on overall survival (OS) and second, to examine the association between the use of chemotherapy prior to or after biomarker testing and OS. Methods: The Flatiron Health EHR-derived database was used to identify patients with ALK-positive (ALK+) advanced NSCLC diagnosed between 1/1/2011 - 9/30/2018. The median time from ALK+ test result to ALKi start was used to separate patients into early versus delayed treatment cohorts. To account for potential immortal time bias, times from ALK+ test result to ALKi start from the delayed cohort were sampled with replacement and used to create modified index dates among the early cohort. Cox proportional hazards models adjusting for baseline characteristics (i.e. ECOG) were used to assess the association between delayed ALKi start and OS and the use of chemotherapy with OS. Results: 422 patients with ALK+ aNSCLC were included in this analysis with a median time from test result to ALKi start of 3 weeks. 88 patients (20.9%) received chemotherapy prior to starting their ALKi. Delayed ALKi use was associated with a 2.3 fold increase in risk of mortality (HR [95% CI]: 2.30 [1.28, 4.15], p < 0.01). There was no difference in survival observed between those who had received chemotherapy prior to initiating their ALKi and those who did not receive chemotherapy (HR [95% CI]: 0.99 [0.62, 1.58]). Among those who initiated chemotherapy prior to their ALK+ test result, the continued use of chemotherapy prior to initiating an ALKi did not result in differences in OS compared to those who switched to an ALKi without continuing chemotherapy (HR [95% CI]: 1.03 [0.44, 2.41]). Conclusions: Delayed initiation of ALKi may result in poor outcomes in patients with ALK+ NSCLC. Receipt of chemotherapy prior to ALKi or the duration of chemotherapy did not impact survival. Future strategies to improve the time to therapy initiation may be useful in improving patient outcomes.

Overestimation of tumor mutational burden (TMB) using algorithms compared to germline subtraction

2621

Background: TMB is an emerging predictor of survival with immunotherapy. TMB is determined by taking the difference between somatic and germline datasets when tumor-normal pairs are available. In the case of commonly utilized tumor-only sequencing, additional steps are needed to estimate the somatic alterations. Computational tools have been developed that determine germline contribution based on sample copy state, purity estimates and occurrence of the variant in population databases. Given the potential bias of population datasets, we hypothesized that tumor-only filtering approaches may overestimate the actual TMB. Methods: We assessed the TMB from 50 tumors in 10 diseases including all missense, indels, and frameshift variants with an allelic fraction (AF) ≥5% and Coverage ≥100X within the tumor. Tumor-only TMB was evaluated against the gold standard of matched germline subtracted TMB at three levels. Level 1 removed all the tumor-only variants with AF in the non-TCGA ExAC database ≥1%. Level 2 removed all variants observed in population databases simulating a naive approach of removing germline variation. Level 3 used an internal tumor-only pipeline for calculating TMB. Results: There were significantly higher estimates of TMB with Level 1, Level 2 and Level 3 tumor-only filtering approaches than that determined by germline subtraction, resulting in significant bias. Whereas there was no correlation between TMB estimates and tumor-germline TMB for Level 1 filtering, there were improvements in correlations for Level 2 and Level 3. Conclusions: The tumor-only approaches that filter variants in population databases overestimate TMB compared to that determined by germline subtraction. Despite improved correlations with more stringent filtering approaches, these falsely elevated estimates may result in the inappropriate categorization of tumor specimens and negatively impact clinical trial results and patient outcomes. [Table: see text]

Retrospective review of 11C-choline detected thoracic lesions in prostate cancer

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.

Immunotherapy-related toxicities: More common than originally reported?

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]

Representation of minorities in oncology clinical trials: Review of the past 14 years

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]

Checkmate 743: A phase 3, randomized, open-label trial of nivolumab (nivo) plus ipilimumab (ipi) vs pemetrexed plus cisplatin or carboplatin as first-line therapy in unresectable pleural mesothelioma

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.

ATOMIC-Meso: A randomized phase 2/3 trial of ADI-PEG20 or placebo with pemetrexed and cisplatin in patients with argininosuccinate synthetase 1-deficient non-epithelioid mesothelioma

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.

Bim and soluble PD-L1 (sPD-L1) as predictive biomarkers of response to anti-PD-1 therapy in patients with melanoma and lung carcinoma

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.

Phase I/III trial of atezolizumab with carboplatin and etoposide in ES-SCLC in first-line setting (IMpower133)

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.

Chromoplectic TPM3-ALK rearrangement in a patient with inflammatory myofibroblastic tumor who responded to ceritinib after progression on crizotinib

Ceritinib resulted in a significant, durable response of a metastatic inflammatory myofibroblastic tumor (IMT) after failure of crizotinib. A chromoplectic TPM3–ALK rearrangement involving many known oncogenes was found in the residual IMT. Ceritinib may be useful for patients with IMT after failure of crizotinib, and chromoplexy may have a role in the oncogenesis or treatment resistance of IMTs.

Background

Inflammatory myofibroblastic tumors (IMTs) are rare sarcomas that can occur at any age. Surgical resection is the primary treatment for patients with localized disease; however, these tumors frequently recur. Less commonly, patients with IMTs develop or present with metastatic disease. There is no standard of care for these patients and traditional cytotoxic therapy is largely ineffective. Most IMTs are associated with oncogenic ALK, ROS1 or PDGFRβ fusions and may benefit from targeted therapy.

Patient and methods

We sought to understand the genomic abnormalities of a patient who presented for management of metastatic IMT after progression of disease on crizotinib and a significant and durable partial response to the more potent ALK inhibitor ceritinib.

Results

The residual IMT was resected based on the recommendations of a multidisciplinary tumor sarcoma tumor board and analyzed by whole-genome mate pair sequencing. Analysis of the residual, resected tumor identified a chromoplectic TPM3–ALK rearrangement that involved many other known oncogenes and was confirmed by rtPCR.

Conclusions

In our analysis of the treatment-resistant, residual IMT, we identified a complex pattern of genetic rearrangements consistent with chromoplexy. Although it is difficult to know for certain if these chromoplectic rearrangements preceded treatment, their presence suggests that chromoplexy has a role in the oncogenesis of IMTs. Furthermore, this patient's remarkable response suggests that ceritinib should be considered as an option after progression on crizotinib for patients with metastatic or unresectable IMT and ALK mutations.

Temporal and spatial discordance of programmed cell death-ligand 1 expression and lymphocyte tumor infiltration between paired primary lesions and brain metastases in lung cancer

The tumor microenvironments of paired primary lung cancers and brain metastases are significantly different, such that many of the metastases lose PD-L1 expression, lymphocyte infiltration or both with greater discrepancies over time. The spatial and temporal heterogeneity of PD-L1 expression may limit its use as a tissue-based predictive biomarker in lung cancer.

Background

The dynamics of PD-L1 expression may limit its use as a tissue-based predictive biomarker. We sought to expand our understanding of the dynamics of PD-L1 expression and tumor-infiltrating lymphocytes (TILs) in patients with lung cancer-related brain metastases.

Experimental design

Paired primary lung cancers and brain metastases were identified and assessed for PD-L1 and CD3 expression by immunohistochemistry. Lesions with 5% or greater PD-L1 expression were considered positive. Agreement statistics and the χ² or Fisher's exact test were used for analysis.

Results

We analyzed 146 paired lesions from 73 cases. There was disagreement of tumor cell PD-L1 expression in 10 cases (14%, κ = 0.71), and disagreement of TIL PD-L1 expression in 19 cases (26%, κ = 0.38). Most paired lesions with discordant tumor cell expression of PD-L1 were obtained 6 or more months apart. When specimens were categorized using a proposed tumor microenvironment categorization scheme based on PD-L1 expression and TILs, there were significant changes in the classifications because many of the brain metastases lacked either PD-L1 expression, tumor lymphocyte infiltration or both even when they were present in the primary lung cancer specimens (P = 0.009).

Conclusions

We identified that there are significant differences between the tumor microenvironment of paired primary lung cancers and brain metastases. When physicians decide to treat patients with lung cancer with a PD-1 or PD-L1 inhibitor, they must do so in the context of the spatial and temporal heterogeneity of the tumor microenvironment.

Implications of Programmed Cell Death 1 Ligand 1 Heterogeneity in the Selection of Patients With Non-Small Cell Lung Cancer to Receive Immunotherapy

The use of programmed cell death 1 ligand 1 (PD-L1) as a predictive biomarker to select patients to receive programmed cell death 1 (PD-1) or PD-L1 inhibitors in non-small cell lung cancer (NSCLC) is limited by the definitions of positivity, interassay agreement, and intra- and intertumoral heterogeneity of expression. Although PD-L1 expression enriches for responses, the lack of expression does not exclude clinical benefit.

Prospective evaluation of protein C and factor VIII in prediction of cancer-associated thrombosis

Venous thromboembolism (VTE) is a preventable disease, yet it is one of the leading causes of death among patients with cancer. Improving risk stratification mechanisms will allow us to personalize thrombo-prophylaxis strategies. We sought to evaluate Collagen and Thrombin Activated Platelets (COAT-platelets) as well as protein C and factor VIII as biomarkers predictive of cancer-associated thrombosis in a prospective cohort of patients with cancer. Protein C was selected as a candidate based on bioinformatics prediction. Blood samples were collected before chemotherapy. All specimen processing was blinded to clinical data. Surveillance and adjudication of the main outcome of VTE was performed for up to 1 year. We used Cox proportional hazard regression to measure the association of biomarkers and incident events using SAS 9.2 for all statistical analysis. Death was modeled as a competing event. Among 241 patients followed for an average of 10.4 months, 15% died and 13% developed a VTE. COAT-platelets were not predictive of VTE. Low levels of pre-chemotherapy protein C (<118%) (HR 2.5; 95% CI 1.1-5.5) and high baseline factor VIII (>261% I) (HR 3.0; 95% CI 1.1-8.0) were predictive of VTE after adjusting for age, Khorana prediction risk, metastatic disease and D dimer. In addition, low protein C was predictive of overall mortality independent of age, metastatic disease and functional status (HR 2.8; 95% CI 1.3-6.0). Addition of these biomarkers to cancer-VTE risk prediction models may add to risk stratification and patient selection to optimize thrombo-prophylaxis.

Severe hepatic dysfunction is associated with venous thromboembolic events in phase 1 clinical trials

INTRODUCTION

Venous thromboembolic events (VTEs) are a significant cause of death in patients with cancer. The incidence of VTE is not well characterized in early phase clinical trials of novel antineoplastic agents, or in hepatic dysfunction studies designed for patients with varying degrees of liver test abnormalities. We compared the incidences of VTE in phase 1 clinical trials (P1CTs) and hepatic dysfunction trials (HDCTs) sponsored by the Cancer Therapy Evaluation Program of the National Cancer Institute (NCI) of the United States.

MATERIALS & METHODS

We reviewed individual patient records of 1841 subjects for symptomatic VTE diagnosed while on study: 1328 subjects on 42 P1CTs, and 513 subjects on 9 HDCTs. The NCI's Organ Dysfunction Working Group definitions were used to categorize patients. The incidences of VTEs between patients were compared by the Chi square test. Confounders were evaluated with the Cochran-Mantel-Haenszel method.

RESULTS & CONCLUSIONS

There were 43 VTEs identified among all subjects (2.3%). There were significantly more VTE observed in the subjects on P1CTs (n=38, 2.9%) than in the subjects on HDCTs (n=5, 1.0%; RR 0.341, 95% 0.13-0.86, p=0.015). For patients on HDCTs, those with severe dysfunction had a high incidence of VTE (RR 10.5 (1.12-93.6), p=0.021) that remained significant in a multivariate model. VTEs were observed less frequently in patients who were enrolled in HDCT than those who were enrolled in P1CT; however, patients with severe hepatic dysfunction were more likely to experience VTE. Severe liver test abnormalities may not be protective against VTE in patients with malignancies receiving chemotherapy.