Koczywas, Marianna

The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Small Cell Lung Cancer (SCLC) provide recommended management for patients with SCLC, including diagnosis, primary treatment, surveillance for relapse, and subsequent treatment. This selection for the journal focuses on metastatic (known as extensive-stage) SCLC, which is more common than limited-stage SCLC. Systemic therapy alone can palliate symptoms and prolong survival in most patients with extensive-stage disease. Smoking cessation counseling and intervention should be strongly promoted in patients with SCLC and other high-grade neuroendocrine carcinomas. The “Summary of the Guidelines Updates” section in the SCLC algorithm outlines the most recent revisions for the 2022 update, which are described in greater detail in this revised Discussion text.

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.

7029 Background: CBP501, a synthetic duodecapeptide, enhances the cytotoxicity of cisplatin in cell lines and xenografts, including NCI-H226 human mesothelioma. CBP501 increases cisplatin influx into tumor cells through an interaction with calmodulin, and inhibits cell cycle progression by abrogating DNA repair at the G2 checkpoint. Phase I clinical trials combining CBP501 with cisplatin alone or with pemetrexed showed acceptable safety profiles and suggested activity. The most common toxicity of CBP501 is infusion-related urticaria, which is easily managed with diphenhydramine. Methods: Chemotherapy-naive patients with unresectable MPM were stratified by histology (epithelioid vs other) and performance status (PS 0-1 vs 2) and randomized 2:1 to Arm A: pemetrexed/cisplatin plus CBP501 25 mg/m2 IV (42 pts planned), or Arm B: pemetrexed/cisplatin alone at standard doses (21 pts planned). Patients continued on treatment until progression or intolerance; no maintenance therapy was delivered. The primary endpoint is progression free survival (PFS) in Arm A; if > 23 of the 42 patients remain free of progression more than 4 months, the combination will be deemed worthy of further study. In addition to standard CT imaging to assess response and PFS, PET scans, pulmonary function tests, and mesothelin levels were performed. Results: Enrollment was completed in October 2011. 65 pts from 14 institutions were randomized, and 63 were treated. Patient characteristics in the two arms were similar and as follows: median age 65, 82% male, 71% epithelioid histology, 8% PS2. Grade 3/4 treatment-related toxicities were uncommon, no different than expected from standard chemotherapy, and comparable in the two arms. 70% of patients treated with CBP501 had infusion reactions, all grade 1-2. The best overall response rate in evaluable patients (modified RECIST, investigator assessed) was 12/37 (32%) (95% CI 18-50) in Arm A, and 3/22 (14%) (95% CI 3-35) in Arm B. The median number of chemotherapy cycles was 5.5 in Arm A, 5 in Arm B. Conclusions: Data on the primary endpoint of PFS in Arm A are maturing and will be presented at the meeting.