A phase II study of atezolizumab and cobimetinib in PD-1/PD-L1 inhibitor resistant or refractory non-small cell lung cancer: ETCTN #10166

TPS9638

Background: Use of checkpoint inhibitors, alone or with chemotherapy, has emerged as the preferred standard treatment for patients with advanced, driver-negative non-small cell lung cancer (NSCLC). While outcomes are superior to chemotherapy alone, only a subset of patients achieve durable response and long term survival. One potential mechanism of primary resistance to checkpoint inhibitors is the lack of tumor-infiltrating lymphocytes. Inhibition of mitogen-activated protein kinase (MAPK) kinase (MEK) increases the number of CD8+ T-cell within a tumor and has shown synergy with anti-programmed death-ligand 1 (PD-L1) antibodies. The combination of the MEK inhibitor cobimetinib and the PD-L1 antibody atezolizumab has led to limited responses in colorectal cancer, a tumor typically non-responsive to checkpoint inhibition. This phase II trial explores the combination of cobimetinib and atezolizumab in patients with PD(L)1-refractory NSCLC. Methods: This phase II study is being conducted through the Experimental Therapeutics Clinical Trials Network (ETCTN #10166). Eligible patients have advanced NSCLC with primary resistance to anti-PD(L)1 therapy (defined as progression noted within 6 months of initiating therapy) and tumor amenable to serial core biopsy. Patients will receive atezolizumab 840mg intravenously every 2 weeks and cobimetinib 60mg orally for 21 days in 28-day cycles. Two cohorts will enroll in parallel, defined by presence or absence of a KRAS mutation. Each cohort will employ a Simon two-stage design to test a null rate of 5% vs. 25% (power = 0.90, □ = 0.10). If > 1 of 9 patients in stage 1 achieve a partial response, an additional 15 patients are enrolled and if > 3 patients achieve a durable response, the combination will be worthy of further investigation. The primary endpoint is durable (> 6 months) response rate. Secondary endpoints are overall response rate, progression free survival, overall survival, duration of response and adverse events. Biopsies performed at baseline and after 3 weeks of therapy will assess the change in the density of tumoral CD8+ T-cells. Whole exome sequencing and immune cell profiling will also be performed on serial samples. Enrollment was initially limited to KRAS-mutant NSCLC. Prespecified activity goal for the first stage of accrual has been met; second stage accrual began in September 2019. Enrollment to the KRAS wild-type cohort will commence. Clinical trial information: NCT03600701 .

Phase II randomized trial of first-line pembrolizumab and vorinostat in patients with metastatic NSCLC (mNSCLC)

9567

Background: Histone deacetylase inhibitors may enhance tumor immunogenicity through various mechanisms including induced expression of T cell chemokines. A previous phase I trial demonstrated the combination of pembrolizumab (P) with vorinostat (V) in mNSCLC was well tolerated with signals of activity in ICI-pretreated pts. We initiated a randomized trial in the first-line setting with the primary objective to determine if the combination had superior ORR compared to pembrolizumab monotherapy. Methods: Pts with treatment-naïve mNSCLC and PD-L1 expression ≥ 1% were eligible. Pts were randomized open-label 1:1 to receive P 200 mg IV q3 wk as monotherapy [Arm A] or P 200 mg IV q3 wk plus V 400 mg PO daily [Arm B]. The primary endpoint was overall response rate (ORR). Secondary endpoints included DOR, PFS and OS. Tumor biopsies were collected both pre- and on-treatment (day 15-21) for analysis of CD8+ TIL, scored using a 0-3 scale in tumor beds. Here we report results after a preplanned interim analysis for efficacy, with accrual ongoing to a planned total of 39 patients per arm. Results: Between 7/2017 – 1/2019, 49 pts were enrolled, with 47 pts evaluable for response (24 in Arm A and 23 in Arm B). Median age was 69 (range 47 - 87), 49% female, ECOG PS 0/1 in 11%/89%. PD-L1 TPS was ≥50% in 13/24 (54%) of pts in Arm A, and in 13/23 (57%) of pts in Arm B. The most common TRAEs in Arm A included diarrhea (13%), fatigue (8%), and pruritus (8%). 3 pts in Arm A experienced grade ≥ 3 irAEs (including 1 each of grade 3 hepatitis, pneumonitis, and rash). The most common TRAEs in Arm B included anorexia (43%), fatigue (43%), nausea (35%) and increased creatinine (35%). 1 pt in Arm B experienced grade ≥ 3 irAE (1 grade 3 pneumonitis). Pre-treatment CD8+ TIL were not significantly different between Arm A and Arm B (p = 0.85) with the majority of tumors in both arms having a low TIL score of 1 (65% Arm A and 73.7% Arm B). A significant increase from pre-treatment to on-treatment TIL scores was seen in both Arm A (p = 0.001) and Arm B (p = 0.002). The ORR in Arm B pts with low pre-treatment TIL (score = 1) pts was substantially higher (66.7%) than in Arm A (33.3%), suggesting the combination may be especially beneficial against low TIL tumors. Conclusions: The combination arm had a considerably higher ORR compared to pembrolizumab monotherapy, with a manageable toxicity profile. The combination of pembrolizumab plus vorinostat in mNSCLC warrants further investigation. Clinical trial information: NCT02638090 . [Table: see text]

Trastuzumab deruxtecan (T-DXd; DS-8201) in patients with HER2-mutated metastatic non-small cell lung cancer (NSCLC): Interim results of DESTINY-Lung01

9504

Background: T-DXd is an antibody-drug conjugate composed of an anti-HER2 antibody, cleavable tetrapeptide-based linker, and topoisomerase I inhibitor payload. In a phase I trial, patients (pts) with HER2-mutated NSCLC who received T-DXd had a confirmed objective response rate (ORR) of 72.7% (8/11) (Tsurutani et al, WCLC 2018). DESTINY-Lung01 (NCT03505710) is an ongoing, multicenter, phase II study of T-DXd in pts with non-squamous NSCLC overexpressing HER2 or containing a HER2-activating mutation. We report data for the cohort with HER2 mutations after a median follow-up of 8.0 mo (range, 1.4-14.2 mo). Methods: Pts were treated with T-DXd 6.4 mg/kg every 3 weeks. The primary endpoint was confirmed ORR (complete response [CR] + partial response [PR]) by ICR. Additional endpoints were disease control rate (DCR; CR + PR + stable disease), duration of response (DOR), progression-free survival (PFS), and safety. Results: At data cutoff (25 Nov 2019), 42 pts (64.3% female) had received T-DXd. Median age was 63.0 years (range, 34-83 years; < 65 y, 59.5%); 45.2% had central nervous system metastases; ECOG performance status was 0 in 23.8% of pts and 1 in 76.2%. HER2 mutations were predominantly in the kinase domain (90.5%). Most pts (90.5%) had prior platinum-based chemotherapy and 54.8% had anti–PD-1 or –PD-L1 treatment; median number of prior treatment lines was 2 (range, 1-6). Median treatment duration was 7.75 mo (range, 0.7-14.3 mo); 45.2% of pts remained on treatment. Confirmed ORR by ICR among the 42 pts was 61.9% (95% CI, 45.6%-76.4%); median DOR was not reached at data cutoff; 16 of 26 responders remained on treatment at data cutoff; DCR was 90.5% (95% CI, 77.4%-97.3%); estimated median PFS was 14.0 mo (95% CI, 6.4-14.0 mo). All pts (42/42) had treatment-emergent adverse events (TEAEs); 64.3% were grade ≥ 3 (52.4% drug-related), including decreased neutrophil count (26.2%) and anemia (16.7%). There were 5 cases (11.9%) of drug-related interstitial lung disease (ILD) as adjudicated by an independent committee (all grade 2, no grade ≥ 3) and 1 case of grade 1 ILD is pending adjudication. TEAEs led to dose interruption in 25 pts (59.5%), dose reduction in 16 pts (38.1%), and treatment discontinuation in 10 pts (23.8%). Conclusions: T-DXd demonstrated promising clinical activity with high ORR and durable responses in pts with HER2-mutated NSCLC. The safety profile was generally consistent with previously reported studies. Clinical trial information: NCT03505710 .

Phase I/Ib study of pembrolizumab and vorinostat in patients with metastatic NSCLC (mNSCLC): Updated results

9073

Background: Histone deacetylase inhibitors (HDACi) enhance tumor immunogenicity through several mechanisms and may augment response to immune checkpoint inhibitors (ICI). We report updated results from a phase I/Ib trial testing the combination of oral HDACi vorinostat (V) with PD-1 inhibitor pembrolizumab (P) in mNSCLC. Methods: In phase I, pts with ICI-naïve or ICI-pretreated mNSCLC were treated with P (200mg IV q3 wk) + V (200 or 400 mg PO daily). In phase Ib expansion, pts were required to have progressed on prior ICI treatment. Primary endpoints were safety/tolerability; secondary endpoints included RR, PFS, DOR, and OS. Tissue and blood specimens from pre- and on-treatment were collected for correlative analyses to determine tumor gene expression changes, T cell density and levels of myeloid-derived suppressor cells. Results: Between 3/2016 - 12/2018, Phase I: 13 pts were treated (4 at 200mg, and 9 at 400mg V dose); and Phase Ib: 20 pts were treated. Median age: 68 (range 38-82); Females: 11 (33%); ECOG 1: 31 (94%); and never/former/current smokers: 3/22/8 (9%/67%/24%). PD-L1 expression was < 1% in 8/33 (18%), ≥1-49% in 7/33 (21%), ≥ 50% in 9/33 (27%) and unknown in 11/30 (33%). No DLTs or treatment related deaths were observed. The RP2D was P 200mg and V 400mg. Most common any grade AEs was fatigue (11%) and nausea/vomiting (8%). 2 (6%) patients had treatment discontinued due to toxicity. 30 pts are evaluable for response, 6 ICI-naïve and 24 ICI-pretreated. 4 (13%) had PR (2 confirmed), 16 (53%) had SD, and 10 (33%) had PD for a disease control rate of 67%. In the ICI-pretreated Ib cohort, 3 pts (1 confirmed; 2 unconfirmed) had a PR and 10 had SD (8 confirmed). For ICI-pretreated pts, mPFS was 3.2 and mOS was 7.3 months, and 1-year PFS was 17% (4 pts). For ICI-naïve, mPFS was 7.6 months and mOS was 16 months. CD8 T cell presence in tumor stromal regions was associated with benefit to P + V treatment. Conclusions: P + V were well tolerated. The combination demonstrates preliminary anti-tumor activity despite progression on prior ICI treatment and stromal CD8 T cells may be associated with benefit from P + V treatment. A randomized phase II portion of this study, examining P combined with V vs. placebo in immunotherapy naïve pts, is ongoing. Clinical trial information: NCT02638090.