Stinchcombe, Thomas E.

Importance Outcomes for patients with unresectable stage III non–small cell lung cancer (NSCLC) treated with chemoradiation therapy (CRT) have improved with adjuvant immune checkpoint inhibitors, with a reported 5-year overall survival benefit of approximately 10% for adjuvant durvalumab vs placebo after completion of CRT without progression and with preserved performance status. Starting atezolizumab prior to CRT may allow more patients to benefit from immunotherapy. Objective To evaluate clinical outcomes of patients treated with atezolizumab before and after CRT for unresectable stage III NSCLC. Design, Setting, and Participants This single-cohort, phase II, nonrandomized controlled trial was conducted at 11 US sites. Patients with pathologically confirmed, unresectable stage III NSCLC who were treatment naive and had good performance status were enrolled between January 3, 2018, and July 24, 2019. Data were locked on March 21, 2023. Interventions Patients received four 21-day cycles of atezolizumab, 1200 mg intravenously, with therapy administered on day 1 of each cycle. Patients not experiencing tumor progression continued to CRT (60 Gy to involved fields) concurrent with weekly carboplatin area under the curve of 2 and paclitaxel, 50 mg/m 2 , followed by planned consolidation carboplatin area under the curve of 6 and paclitaxel, 200 mg/m 2 , for two 21-day cycles. Patients not experiencing progression continued atezolizumab, 1200 mg, every 21 days to complete 1 year of therapy. Main Outcomes and Measures The primary end point was the disease control rate at 12 weeks. Secondary end points were progression-free survival, overall survival, overall response rate, safety, and translational science end points. Results A total of 62 patients (median [range] age, 63.9 [38.1-86.5] years; 32 female [51.6%]) were enrolled and received at least 1 dose of atezolizumab. The disease control rate at 12 weeks was 74.2% (80% CI, 65.7%-81.4%). Median progression-free survival was 30.0 months (95% CI, 15.8 to not evaluable), and the median overall survival was not reached. The overall survival rate at 24 months was 73.7% (95% CI, 63.4%-85.7%), and the overall response rate was 66.2%. Seventeen patients (27.4%) experienced grade 3 or higher immune-related adverse events, including 1 with grade 5 pneumonitis and 1 with grade 4 Guillain-Barré syndrome. Thirty patients (48.4%) experienced grade 3 or higher treatment-related adverse events. Conclusions and Relevance These findings suggest that neoadjuvant atezolizumab merits further study based on safety and encouraging outcomes. Trial Registration ClinicalTrials.gov Identifier: NCT03102242

TPS8125 Background: Sarcomatoid mesothelioma is the most aggressive form of pleural mesothelioma and is associated with the worst prognosis of the histologic variants of this disease. In the Checkmate 743 clinical trial the patients with sarcomatoid mesothelioma who received ipilimumab and nivolumab had survival outcomes that were similar to those of patients with epithelioid mesothelioma. In comparison, the patients with sarcomatoid mesothelioma who received chemotherapy had the worst outcomes in this trial, highlighting the known limited efficacy of chemotherapy against this histologic variant. Checkmate 743 demonstrated that ipilimumab and nivolumab is a new standard of care for non-epithelioid mesothelioma. Surgery typically has not been offered to this group of patients given their historically poor outcomes. With the significant survival gains seen patients with sarcomatoid mesothelioma treated with immunotherapy, we hypothesized that surgery may extend the benefits seen with immunotherapy. Methods: Alliance for Clinical Trials in Oncology A082101 is a prospective, phase 2 nonrandomized clinical trial for patients with sarcomatoid mesothelioma. The co-primary objectives are to determine the percentage of patients with potentially resectable sarcomatoid mesothelioma able to proceed with surgery after neoadjuvant ipilimumab and nivolumab, and the progression-free survival (PFS) at 12 months (12-month PFS) after the initiation of ipilimumab and nivolumab. For sample size determination, we assumed that if the true rate of surgery is 75% or greater, it would indicate that neoadjuvant immunotherapy is feasible to be given prior to surgery. On the other hand, if the true rate of surgery is 50% or less it would indicate that neoadjuvant immunotherapy is not worthy of further investigation. Twenty-six (26) eligible patients will be needed to receive neoadjuvant immunotherapy. If 16 or fewer of the 26 eligible patients proceed to surgery, it will be concluded that the experimental therapy is not worthy of further investigation. Otherwise, it will be concluded that the experimental therapy is worthy of further investigation. Safety monitoring will be done through a 6-week run-in for the first 10 patients to assess for pre-operative and post-operative toxicities and complications. Sequential boundaries will be used to monitor severe toxicity and complication rates. Accrual will be halted if excessive numbers of severe toxicity and complications in pre-operative and post-operative phases are seen. The accrual and safety data will be summarized in reports for semiannual reviews by Alliance Data and Safety Monitoring Board. Tumor and blood-based biomarkers will be included as exploratory biomarkers. Support: U10CA180821, U10CA180882, U24 CA196171; https://acknowledgments.alliancefound.org . Clinical trial information: NCT05647265 .

TPS8123 Background: A minority of patients with unresectable stage III non-small cell lung cancer (NSCLC) may be cured by chemoradiotherapy (CRT). Adjuvant checkpoint inhibition through PD-L1 blockade after CRT improved survival compared to placebo in the PACIFIC trial (median progression-free survival (mPFS) 16.9 vs 5.6 months (mo), median overall survival (mOS) 47.5 vs 29.1 mo), but overall survival at 5 years remains below 50% (Spigel D, et al J Clin Oncol 2022, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9015199/ . Only patients completing CRT without progression and with good performance status were eligible for this approach. Neoadjuvant checkpoint inhibition would allow more patients the opportunity to benefit from immunotherapy and may attenuate tumor-related immunosuppression via depletion of regulatory T cells and clonal expansion of effector T cells, thereby improving tumor immunogenicity. Neoadjuvant atezolizumab had favorable outcomes compared to historic PACIFIC data in the phase II single arm trial, AFT-16 (mPFS 30 mo and mOS not reached). Whether combination immunotherapy therapy before CRT will improve outcomes in this setting is the question posed in the AFT-57 trial. Methods: This phase II randomized Alliance Foundation Trials study (AFT-57) will evaluate safety and efficacy of atezolizumab with or without the anti-TIGIT monoclonal antibody, tiragolumab, before and after definitive CRT with concurrent atezolizumab. The primary endpoint is PFS in the two experimental arms with a goal to select the most promising regimen for further study. AFT-57 will randomly assign 158 patients with stage III NSCLC (AJCC v8), Eastern Cooperative Oncology Group performance status 0-1, no active autoimmune disease and no underlying organ dysfunction to 2 cycles of neoadjuvant atezolizumab (1200 mg intravenously [IV] every 21 days) with or without tiragolumab (600 mg IV). Non-progressing patients will receive carboplatin and paclitaxel weekly with atezolizumab 1200 mg IV every 21 days concurrent with 60 Gray involved field thoracic radiation in 30 daily fractions (Monday - Friday) followed by atezolizumab with or without tiragolumab on the same schedule as the neoadjuvant doses, with a plan to complete one year of therapy. A pilot cohort of 20 patients for whom tiragolumab will be combined with atezolizumab during chemoradiotherapy is planned toward the end of accrual. Correlative science includes tissue and blood-based immune-related biomarkers at baseline and during therapy. This trial utilizes the Alliance Participant Engagement Portal, a patient-facing site designed to provide information and resources to Alliance clinical trial participants. The trial was activated on 12/7/23 with the first patient screened 1/19/24. Clinical trial information: NCT05798663 .

1105 Background: Approximately 2-5% of breast cancers harbor HER2 mutations, often occurring in hormone receptor-positive (HR+) disease. There are currently no approved treatment options for patients (pts) with HER2-mutated metastatic breast cancer (HER2-mut MBC). Tucatinib (TUC) is a tyrosine kinase inhibitor highly selective for HER2 and is approved for previously treated HER2+ MBC with or without brain metastases in combination with trastuzumab (Tras) and capecitabine. Here, we report the efficacy and safety results of TUC combined with Tras in pts with previously treated HER2-mut MBC. Methods: SGNTUC-019 (NCT04579380) is an open-label phase 2 basket study evaluating efficacy, safety, and tolerability of TUC and Tras in pts with metastatic HER2-altered solid tumors. Pts in the HER2-mut MBC cohort must have HER2 mutations determined locally by tissue- or blood-based next-generation sequencing, not be HER2+ per local testing, been previously treated with ≥1 systemic therapy in the locally advanced, unresectable, or metastatic setting, and if HR+, have received a CDK4/6 inhibitor. Pts were treated in 21-day cycles with TUC (300 mg orally twice a day) and Tras (8 mg/kg IV followed by 6 mg/kg every 3 wks). Pts with HR+ disease also received fulvestrant (F; 500 mg IM once every 4 wks starting from cycle 1 day 1, and cycle 1 day 15). Disease status was determined based on RECIST v1.1 with assessments performed every 6 wks for 24 wks and every 12 wks thereafter. The primary endpoint is cORR per investigator assessment. Secondary endpoints include OS, DCR, DOR, PFS, and safety. Results: As of Nov 1, 2023, 31 pts were enrolled in the HER2-mut MBC cohort. The median duration of follow-up for OS was 15.0 months. Twenty-seven (87%) pts had HR+ disease and 18 (58%) had lobular histology. The pts received a median of 4 prior lines of systemic therapy in any setting. cORR was 41.9% (90% CI, 26.9-58.2) with 13 responses including 2 complete responses. Median DOR was 12.6 months (90% CI, 4.7, not estimable), DCR was 80.6% (n=25; 90% CI, 65.3-91.2), median PFS was 9.5 months (90% CI, 5.4-13.8), and median OS was 20.1 months (90% CI, 15.9 to not estimable). The most common treatment-emergent adverse events (TEAEs) reported were diarrhea (64.5%) and nausea (35.5%). The most common grade ≥3 TEAEs reported were diarrhea (13%), alanine aminotransferase increase (10%), and hypertension (10%). Two (6.5%) pts discontinued TUC due to TEAEs, but these pts continued Tras. No deaths were due to TEAEs. Additional biomarker analyses will be included in the presentation. Conclusions: The investigational combination of TUC and Tras, plus F in pts with HR+ disease, was well tolerated and had clinical activity in pts with previously treated HER2-mut MBC. The results support further evaluation of the combination of TUC and Tras as a potential treatment option for this pt population. Clinical trial information: NCT04579380 .

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical trial updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported. Patients with early-stage non–small-cell lung cancer (NSCLC) who undergo curative surgical resection are at risk for developing second primary lung cancer (SPLC). Cancer and Leukemia Group B 140503 (Alliance) was a multicenter, international, randomized, phase III trial in patients with stage T1aN0 NSCLC (using the TNM staging system seventh edition) and demonstrated the noninferiority for disease-free survival between sublobar resection (SLR) and lobar resection (LR). After surgery, patients underwent computed tomography surveillance as defined by the protocol. The determination of a SPLC was done by the treating physician and recorded in the study database. We performed an analysis of the rate of SPLC (per patient per year) and the 5-year cumulative incidence in the study population and within the SLR and LR arms. Median follow-up was 7 years. The rate per patient per year in the study population, in the SLR arm, and in the LR arm was 3.4% (95% CI, 2.9 to 4.1), 3.8% (95% CI, 2.9 to 4.9), and 3.1% (95% CI, 2.4 to 4.1), respectively. The estimated 5-year cumulative incidence of SPLC in the study population, SLR arm, and LR arm was 15.9% (95% CI, 12.9 to 18.9), 17.2% (95% CI, 12.7 to 21.5), and 14.7% (95% CI, 10.6 to 18.7), respectively.

PURPOSE To evaluate the efficacy and safety of tucatinib and trastuzumab in patients with previously treated human epidermal growth factor receptor 2–positive (HER2+) metastatic biliary tract cancer (mBTC). METHODS SGNTUC-019 (ClinicalTrials.gov identifier: NCT04579380 ) is an open-label phase II basket study evaluating the efficacy and safety of tucatinib and trastuzumab in patients with HER2-altered solid tumors. In the biliary tract cancer cohort, patients had previously treated HER2 overexpressing or amplified (HER2+) tumors (identified with local testing) with no prior HER2-directed therapy. The primary end point was confirmed objective response rate (cORR) per investigator assessment. Patients were treated on a 21-day cycle with tucatinib (300 mg orally twice daily) and trastuzumab (8 mg/kg intravenously followed by 6 mg/kg every 3 weeks). RESULTS Thirty patients were enrolled. As of data cutoff (January 30, 2023), the median duration of follow-up was 10.8 months. The cORR was 46.7% (90% CI, 30.8 to 63.0), with a disease control rate of 76.7% (90% CI, 60.6 to 88.5). The median duration of response and progression-free survival were 6.0 months (90% CI, 5.5 to 6.9) and 5.5 months (90% CI, 3.9 to 8.1), respectively. At data cutoff, 15 patients (50.0%) had died, and the estimated 12-month overall survival rate was 53.6% (90% CI, 36.8 to 67.8). The two most common treatment-emergent adverse events (TEAEs) were pyrexia (43.3%) and diarrhea (40.0%). Grade ≥3 TEAEs were reported in 18 patients (60.0%), with the most common being cholangitis, decreased appetite, and nausea (all 10.0%), which were generally not treatment related. TEAEs led to treatment regimen discontinuation in one patient, and there were no deaths due to TEAEs. CONCLUSION Tucatinib combined with trastuzumab had clinically significant antitumor activity and was well tolerated in patients with previously treated HER2+ mBTC.

TPS8602 Background: Sarcomatoid mesothelioma is the most aggressive form of pleural mesothelioma and is associated with the worst prognosis of the histologic variants of this disease. In the Checkmate 743 clinical trial the patients with sarcomatoid mesothelioma who received ipilimumab and nivolumab had survival outcomes that were similar to those of patients with epithelioid mesothelioma. In comparison, the patients with sarcomatoid mesothelioma who received chemotherapy had the worst outcomes in this trial, highlighting the known limited efficacy of chemotherapy against this histologic variant. Checkmate 743 demonstrated that ipilimumab and nivolumab is a new standard of care for non-epithelioid mesothelioma. Surgery typically has not been offered to this group of patients given their historically poor outcomes. With the significant survival gains seen patients with sarcomatoid mesothelioma treated with immunotherapy, we hypothesized that surgery may extend the benefits seen with immunotherapy. Methods: Alliance for Clinical Trials in Oncology A082101 is a prospective, phase 2 nonrandomized clinical trial for patients with sarcomatoid mesothelioma. The co-primary objectives are to determine the percentage of patients with potentially resectable sarcomatoid mesothelioma able to proceed with surgery after neoadjuvant ipilimumab and nivolumab, and the progression-free survival (PFS) at 12 months (12-month PFS). For sample size determination, we assumed that if the true rate of surgery is 75% or greater, it would indicate that neoadjuvant immunotherapy is feasible to be given prior to surgery. On the other hand, if the true rate of surgery is 50% or less it would indicate that neoadjuvant immunotherapy is not worthy of further investigation. Twenty-six (26) eligible patients will be needed to receive neoadjuvant immunotherapy. If 16 or fewer of the 26 eligible patients proceed to surgery, it will be concluded that the experimental therapy is not worthy of further investigation. Otherwise, it will be concluded that the experimental therapy is worthy of further investigation. Safety monitoring will be done through a 6-week run-in for the first 10 patients to assess for pre-operative and post-operative toxicities and complications. Sequential boundaries will be used to monitor severe toxicity and complication rates. Accrual will be halted if excessive numbers of severe toxicity and complications in pre-operative and post-operative phases are seen. Tumor and blood-based biomarkers will be included as exploratory biomarkers. Clinical trial information: NCT05647265 .

4007 Background: Biliary tract cancer (BTC) is an aggressive malignancy with a poor prognosis, and current treatment options for advanced BTC are limited, with second-line therapy, FOLFOX and S-1 offering an objective response rate (ORR) of 5.0% and 7.5%, respectively. Up to 20% of BTCs overexpress human epidermal growth factor receptor 2 (HER2). Tucatinib (TUC) is a highly selective HER2-directed TKI approved for HER2-positive (HER2+) metastatic breast and colorectal cancer. Discussed here are the efficacy and safety results of TUC combined with Trastuzumab (Tras) in pts with previously treated HER2+ metastatic BTC. Methods: SGNTUC-019 (NCT04579380) is an open-label phase 2 basket study evaluating efficacy, safety, and tolerability of TUC and Tras in pts with HER2-altered solid tumors. Pts in the BTC cohort had been previously treated with and progressed after ≥1 line of systemic therapy for metastatic disease. Eligible pts had locally determined HER2+ (defined as HER2 overexpression determined by immunohistochemistry [IHC] 3+ or HER2 amplification determined by in situ hybridization assay or next-generation sequencing) metastatic BTC. Pts were treated on a 21-day cycle with TUC (300 mg orally twice a day) and Tras (8 mg/kg IV followed by 6 mg/kg every 3 wks). Disease status was determined based on RECIST v1.1 with assessments performed every 6 wks for 24 wks and every 12 wks thereafter. The primary endpoint is confirmed objective response rate (cORR) per investigator assessment. Secondary endpoints include overall survival (OS), disease control rate (DCR), duration of response (DOR), progression-free survival (PFS), and safety. Results: Thirty pts were enrolled in the BTC cohort as of data cutoff date of 30 Nov 2022. The median duration of follow-up was 8.3 months. cORR was 46.7% (90% CI, 30.8, 63.0), with 14 responses including 1 complete and 13 partial responses. Median DOR was 6.0 months (90% CI, 5.5, not estimable). DCR was 76.7% (n=23; 90% CI, 60.6, 88.5), and median PFS was 5.5 months (90% CI, 3.9, 8.1). At data cutoff, 13 (43.3%) patients had died, and the 12-months OS rate was 53.8% (90% CI, 35.2, 69.1%). Overall, the most common treatment-emergent adverse events (TEAEs) reported were pyrexia (43.3%) and diarrhea (40.0%). Grade ≥3 TEAEs were reported in 18 (60.0%) of 30 pts; however, only 6 (20.0%) and 2 (6.7%) of these pts had Grade ≥3 TEAEs related to TUC and Tras, respectively. Two (6.7%) pts discontinued TUC due to TEAEs, cholangitis and liver disorder. No deaths were due to TEAEs. Conclusions: The combination of TUC and Tras was well tolerated in pts with previously treated HER2+ metastatic BTC. The observed antitumor activity supports the combination of TUC and Tras as a future chemotherapy-free treatment option for this population with historically poor outcomes. Clinical trial information: NCT04579380 .