Citations

Abstract B-cell activation is increasingly linked to numerous fibrotic lung diseases, and it is well known that aggregates of lymphocytes form in the lung of many of these patients. Activation of B-cells by pattern recognition receptors (PRRs) drives the release of inflammatory cytokines, chemokines, and metalloproteases important in the pathophysiology of pulmonary fibrosis. However, the specific mechanisms of B-cell activation in patients with idiopathic pulmonary fibrosis (IPF) are poorly understood. Herein, we have demonstrated that B-cell activation by microbial antigens contributes to the inflammatory and profibrotic milieu seen in patients with IPF. B-cell stimulation by CpG and β-glucan via PRRs resulted in activation of mTOR-dependent and independent pathways. Moreover, we showed that the B-cell–secreted inflammatory milieu is specific to the inducing antigen and causes differential fibroblast migration and activation. B-cell responses to infectious agents and subsequent B-cell–mediated fibroblast activation are modifiable by antifibrotics, but each seems to exert a specific and different effect. These results suggest that, upon PRR activation by microbial antigens, B-cells can contribute to the inflammatory and fibrotic changes seen in patients with IPF, and antifibrotics are able to at least partially reverse these responses.

e21631 Background: The efficacy of osimertinib in previously EGFR-TKI treated NSCLC patients without T790M mutation remains unclear in real-world practice. We investigated whether osimertinib can provide survival benefit in EGFR-mutant patients without T790M mutation after 1st/2nd generation TKI treatment. Methods: Between January 1, 2009, and March 31, 2019, 417 patients had stage III-IV NSCLC harboring EGFR mutation and 154 out of 417 patients receiving osimertinib as≥2nd-line EGFR-TKI treatment were identified at Mayo Clinic. The time to treatment failure of osimertinib was analyzed by the Kaplan-Meier (KM) estimates. The risk of death post diagnosis was analyzed by Cox proportional hazard models. Results: Among 417 EGFR-mutant patients, higher risk of death was found in patients with age above 65 years, non-adenocarcinoma, no surgery treatment, no radiation treatment, non-exon 19 deletion/exon 21 L858R mutation, higher ECOG PS (2-4), PD-L1 expression of 50% or more, bone metastasis, live metastasis, and adrenal metastasis (all p < 0.05). Moreover, osimertinib as ≥2nd-line TKI treatment in patients with or without T790M revealed lower risk of death compared to 1st/2nd generation TKI treatment without subsequent osimertinib (HR = 0.33; 0.46, and p = 0.0002; 0.0232, respectively). However, among patients receiving osimertinib as ≥2nd-line TKI treatment, patients with T790M did not have superior survival than those without (p = 0.2803). Among 154 patients receiving osimertinib, a higher risk of treatment failure for osimertinib was found in male (HR = 1.72; p = 0.0327), patients with 1st-line TKI duration ≤12 months (HR = 2.16; p = 0.0019), BMI drop > 10% (HR = 1.85; p = 0.0207), PD-L1 levels of 50% or more (HR = 4.28; p = 0.0008), and 1st-line TKI with afatinib (HR = 2.19; p = 0.0136). Nonetheless, osimertinib as ≥2nd-line TKI in patients without 790M mutation did not have higher risk of treatment failure than those with T790M (p = 0.1236). Conclusions: This is the first study to demonstrate that osimertinib can provide similar survival benefit in previously EGFR-TKI treated NSCLC patients without T790M mutation as those with T790M in real-world practice. Additionally, EGFR-mutant patients with PD-L1 expression ≥50% had a higher risk of treatment failure for osimertinib and worse overall survival than those with PD-L1 expression < 50% and may potentially gain benefit from optimizing treatment strategies including immunotherapy.

TPS9079 Background: Pleurectomy/Decortication (P/D) with neoadjuvant or adjuvant chemotherapy has become a common lung-sparing surgical approach for MPM. Adjuvant hemithoracic IMPRINT was developed at Memorial Sloan Kettering Cancer Center and safe in a multi-institutional phase II study, with promising survival outcomes. The National Cancer Institute (NCI) sponsored this phase III randomized cooperative group trial to test the efficacy of this lung-sparing trimodality approach for resectable MPM. Methods: Patients with newly diagnosed MPM amenable to P/D are enrolled and undergo P/D followed by adjuvant platinum/pemetrexed (preferred) or neoadjuvant chemotherapy followed by P/D. Patients are stratified by histologic subtype, resection status (R0/1 vs. R2), and center patient volume (≤10 vs. > 10 P/Ds per year). Within 8 weeks after completion of the second modality patients are randomized 1:1 to undergo hemithoracic IMPRINT vs. no further therapy. All IMPRINT contours and treatment plans will be centrally reviewed. A contouring atlas and treatment planning constraints for target structures and organs at risk including acceptable and unacceptable variations and deviations were developed. Photon and proton therapy are permitted. The primary endpoint of the study is overall survival. Secondary endpoints include local failure-free, distant-metastases-free and progression-free survival, treatment-related toxicities (CTCAE v5.0) and change in quality-of-life (EORTC QLQ-C30 mean score changes at 9 months post randomization). The target accrual is 150 patients. This study was activated on January 29, 2020. Over 20 institutions have already committed to opening the study which is open to all National Clinical Trials Network (NCTN) sites. Treatment planning guidelines and helpful hints for photon and proton therapy will be presented. Conclusions: NRG LU-006 (clinicaltrials.gov: NCT04158141 ) is open to accrual. This is the first NRG Oncology randomized phase III trial on MPM and evaluates the use of IMPRINT following lung-sparing P/D and chemotherapy. This project was supported by grants U10CA180868 (NRG Oncology Operations), U10CA180822 (NRG Oncology SDMC), U24CA180803 (IROC) from the National Cancer Institute (NCI). Clinical trial information: NCT04158141.

9058 Background: Breast cancer gene 1 (BRCA1)-associated protein 1 (BAP1), a nuclear deubiquitinase, is commonly inactivated in malignant mesothelioma. Preclinical data showed that BAP1 inactivation sensitizes mesothelial cells to inhibition of enhancer of zeste-homolog 2 (EZH2), a methyltransferase implicated as an oncogenic driver in this tumor. This study evaluated the safety and efficacy of tazemetostat (TAZ), a potent and selective EZH2 inhibitor, in relapsed/refractory (R/R) malignant mesothelioma with BAP1-inactivation. Methods: EZH-203 (NCT02860286) was a 2-part, open-label, phase 2 study that assessed the pharmacokinetics (PK), safety, and efficacy of TAZ in pts with R/R malignant mesothelioma. In part 1, pts received TAZ 800 mg QD on day 1 (D1) and 800 mg BID, beginning day 2 of cycle 1 (C1). In part 2, pts received 800 mg of TAZ BID on D1 of C1. A two-stage Green-Dahlberg design was used for part 2. Primary endpoints were PK profiling of TAZ in all pts (part 1), and disease control rate (DCR) at week 12 in pts with BAP1-deficient R/R malignant mesothelioma (part 2). Secondary endpoints included safety, overall response rate (ORR), progression-free survival, overall survival, and duration of response (DOR). Results: The study enrolled 74 pts with R/R malignant mesothelioma, 70 pts (95%) were centrally confirmed to be BAP1-deficient. Median prior lines of therapy were 2 (range, 1-9). Observed clinical data in the presence of CYP3A4 inhibitors and inducers suggest a low DDI potential of TAZ. The 12 week DCR was 47% (n = 35). The ORR per RECIST version 1.1 was 3% [complete response: 0%; partial response (PR): 3% (n = 2)]. Of the 2 patients with PR, 1 had a DOR of 21 weeks and the other is ongoing (15.3 weeks at data cut off). 47 pts (64%) and 21 pts (28%) had stable disease (SD) and progressive disease, respectively. Overall, 91% pts discontinued, either due to disease progression (n = 65), death (n = 5), or treatment discontinuation (n = 1). Grade ≥3 treatment-emergent adverse events (TEAEs) occurred in ≤5% of patients, most commonly anemia (5%) and dyspnea (4%). No pts discontinued due to TEAEs. There were no treatment related deaths. Conclusions: Based on disease control rate and stable disease, TAZ showed antitumor activity in pts with BAP1-deficient R/R malignant mesothelioma. TAZ monotherapy was generally well-tolerated. The current data support further clinical evaluation of TAZ in these pts. Furthermore, this trial presents an optimal paradigm for drug development in molecularly-enriched cohorts in mesothelioma. Clinical trial information: NCT02860286.