Nami Hirano

PURPOSE: This is a phase Ib trial of regorafenib plus nivolumab for gastric and colorectal cancer. PATIENTS AND METHODS: Enrolled patients received regorafenib plus nivolumab in a dose-finding part to estimate the maximum tolerated dose. Additional patients were enrolled in a dose-expansion part. Regorafenib of 80-160 mg was administered once daily for 21 days on/7 days off with nivolumab 3 mg/kg every 2 weeks. The primary end point was dose-limiting toxicity (DLT) during the first 4 weeks to estimate the recommended dose. RESULTS: Fifty patients (25 each with gastric and colorectal cancer) were enrolled. All patients had received ≥ 2 previous lines of chemotherapy, including anti-angiogenetic inhibitors in 96% of patients. Seven patients with gastric cancer had previously been treated with immune checkpoint inhibitors. One patient had microsatellite instability-high colorectal cancer, whereas the remaining patients had microsatellite stable or mismatch repair-proficient tumors. Three DLTs (grade 3 colonic perforation, maculopapular rash, and proteinuria) were observed with regorafenib 160 mg; none were observed with 80 or 120 mg. During the dose-expansion part, regorafenib dose was reduced from 120 to 80 mg because of frequent maculopapular rash. The common grade ≥ 3 treatment-related adverse events were rash (12%), proteinuria (12%), and palmar-plantar erythrodysesthesia (10%). Objective tumor response was observed in 20 patients (40%), including 11 with gastric cancer (44%) and 9 with colorectal cancer (36%). Median progression-free survival was 5.6 and 7.9 months in patients with gastric and colorectal cancer, respectively. CONCLUSION: The combination of regorafenib 80 mg plus nivolumab had a manageable safety profile and encouraging antitumor activity in patients with gastric and colorectal cancer, which warrants additional investigations in larger cohorts.

PURPOSE HERALD/EPOC1806 was conducted as a multicenter phase II trial assessing trastuzumab deruxtecan (T-DXd) therapy for patients with human epidermal growth factor receptor 2 ( HER2 )–amplified progressive stage solid tumors detected by cell-free DNA (cfDNA) testing. PATIENTS AND METHODS Patients exhibited advanced solid tumors with HER2 amplification that was identified via next-generation sequencing of cfDNA testing, without the requirement for immunohistochemical HER2 testing. The studied group was administered T-DXd at 5.4 mg/kg once every 3 weeks until onset of disease progression or intolerable toxicity. RESULTS Overall, 4,734 patients underwent cfDNA testing from December 2019 to January 2022, and 252 demonstrated HER2 amplification. Finally, the study included 62 patients with 16 cancer types with a median baseline plasma HER2 copy number (CN) of 8.55 (range, 2.4-73.9). Confirmed overall response rate (ORR) by investigator assessment was 56.5% (95% CI, 43.3 to 69.0), thus showing a value beyond the 5% threshold. Responses were evaluated for 13 cancer types, including KRAS -mutant colorectal (1/3), PIK3CA -mutant endometrial (5/6), and tissue HER2-negative gastric (1/2) cancers. Plasma HER2 CN above versus below the baseline median value did not differ for impact response; however, clearance of HER2 amplification in cfDNA on cycle 2 day 1 had higher response values compared with persistence. Median progression-free survival and response duration were 7.0 (95% CI, 4.9 to 9.7) and 8.8 (95% CI, 5.8 to 11.2) months, respectively, with the majority of complications being mild to moderate. Interstitial lung diseases were identified in 16 (26%) patients, including 14 patients with grade 1 disease, one patient with grade 2 disease, and one patient with grade 3 disease. CONCLUSION T-DXd treatment demonstrated high ORR with durable response in patients with advanced HER2 -amplified solid tumors determined with cfDNA testing.

3014 Background: HER2 ( ERBB2) gene amplification (amp) is a potential therapeutic target beyond breast and gastric cancers. HER2 amp can be detected in plasma cfDNA which may be an alternative to tissue biopsy. HERALD/EPOC1806 was a multicenter, investigator-initiated phase 2 trial of T-DXd for patients with HER2-amplified advanced solid tumors identified by cfDNA testing. Methods: We enrolled adults with advanced solid tumors harboring HER2 amp detected by next-generation sequencing of cfDNA (Guardant360) in the GOZILA study (UMIN000029315). We excluded breast or gastric cancer patients with HER2 overexpression (IHC 3+ or IHC 2+/ISH+). Patients received T-DXd 5.4 mg/kg every 3 weeks until disease progression or unacceptable toxicity. The primary endpoint was investigator-assessed objective response rate (ORR). Results: From December 2019 to January 2022, 4,734 patients were screened by cfDNA in the GOZILA study. Among 252 with HER2 amp, 62 with 16 cancer types were enrolled in HERALD. Median baseline plasma HER2 copy number (CN) was 8.55 (range, 2.4–73.9). All patients but 3 (all with salivary gland cancer) received prior anti-cancer therapy (median, 3 lines; range, 0–8). At a median follow-up of 8.9 months (data cut-off: July 17, 2022), the confirmed ORR was 56.5% (95% CI, 43.3–69.0%), statistically higher than the threshold value of 5%. Responses were observed for 13 cancer types, including KRAS-mutant colorectal (1/3), PIK3CA-mutant endometrial (5/6), and tissue HER2-negative gastric cancers (1/2). Plasma HER2 CN above vs. below the baseline median value did not impact response (ORR: 58.1% vs. 54.8%); however, the clearance vs. persistence of HER2 amp in cfDNA on Cycle 2 Day 1 corresponded to higher response (ORR: 88.0% vs. 22.7%). ORR by independent review was 58.1% (95% CI, 44.8–70.5%), and the disease control rate was 90.3% (95% CI, 80.1–96.4%). Median progression-free survival was 7.0 (95% CI, 4.9–9.7) months, and the median duration of response was 8.8 months (95% CI, 5.8–11.2). Most adverse events were mild to moderate. Interstitial lung diseases occurred in 16 patients (25.8%, G1/G2/G3; 14/1/1). Conclusions: T-DXd achieved a high ORR, durable response with a manageable safety profile in patients with advanced solid tumors and HER2 amp detected in cfDNA. Clinical trial information: JapicCTI-194707 .[Table: see text]

3530 Background: The anti–PD-1 antibody pembrolizumab provided an objective response rate of 28-57% in patients (pts) with Microsatellite Instability–High (MSI-H) metastatic colorectal cancer (mCRC) vs 0% in pts with Non-MSI-H. The WNT/β-catenin signaling has been reported to prevent anti-tumor immunity and promote resistance of anti-PD-1/PD-L1 antibodies. Furthermore, STAT3 has been known to be a key driver of the immune evasion. This study investigates efficacy and safety of the combination of BBI608, which blocks phosphorylated STAT3 and downregulates WNT/β-catenin signaling, with pembrolizumab in pts with mCRC. BBI608 480mg BID with pembrolizumab was determined as RP2D in the phase I part (Kawazoe A, et al. ASCO-GI 2018). Here, we present the preliminary results of the ongoing phase II part. Methods: Phase II part was composed of Cohort A (MSI-H) and Cohort B (Non-MSI-H). The main eligibility criteria was pts with mCRC not responded or intolerant to standard chemotherapies. Primary endpoint was Immune-related objective response rate (irORR) determined by irRECIST. Sample size for Cohort A with 10 pts was determined in an exploratory manner. In Cohort B, according to a null hypothesis and alternative hypothesis; irORR = 5% and 20%, estimating required sample size was 40 pts with a one-sided alpha of 5% and power of 90%. Results: From Feb 2017 to January 2018, 10 pts were enrolled in Cohort A, and 37 pts in Cohort B. As of October 2017, tumor response was evaluated in 3 pts of Cohort A and 25 pts of Cohort B, respectively. Two out of the 3 pts in Cohort A showed confirmed partial response. Among 12pts with right-sided colon in Cohort B, one patient showed confirmed partial response with remarkable decline of CEA level, and two pts showed stable disease lasting more than 16 weeks. Immunohistochemistry before treatment demonstrated the high expressions of PD-L1, CD8, and MHC-class I in the tumor samples from the patient with partial response. No severe or unexpected adverse events occurred up to the present. Conclusions: BBI608 with pembrolizumab showed preliminary efficacy signals with acceptable toxicity for MSI-H as well as Non-MSI-H mCRC pts with right-sided primary. Clinical trial information: NCT02851004.