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MA 05 - Immuno-Oncology: Novel Biomarker Candidates (ID 658)
- Event: WCLC 2017
- Type: Mini Oral
- Track: Immunology and Immunotherapy
- Presentations: 1
MA 05.02 - STK11/LKB1 Loss of Function Genomic Alterations Predict Primary Resistance to PD-1/PD-L1 Axis Blockade in KRAS-Mutant NSCLC (ID 10367)
15:45 - 17:30 | Author(s): A. Plodkowski
The genomic landscape of primary resistance to PD-1 blockade in lung adenocarcinoma (LUAD) is largely unknown. We previously reported that co-mutations in STK11/LKB1 (KL) or TP53 (KP) define subgroups of KRAS-mutant LUAD with distinct therapeutic vulnerabilities and immune profiles. Here, we present updated data on the clinical efficacy of PD-1/PD-L1 inhibitors in co-mutation defined KRAS mutant and wild-type LUAD patients and examine the relationship between genetic alterations in individual genes, tumor cell PD-L1 expression and tumor mutational burden (TMB) using cohorts form the SU2C/ACS Lung Cancer Dream Team and Foundation Medicine (FM).
The cohorts included 924 LUAD with NGS (FM cohort) and 188 patients with KRAS non-squamous NSCLC (SU2C cohort) who received at least one cycle of PD-1/PD-L1 inhibitor therapy and had available molecular profiling. Tumor cell PD-L1 expression was tested using E1L3N IHC (SU2C) and the VENTANA PD-L1 (SP142) assay (FM). TMB was defined as previously described and was classified as high (TMB-H), intermediate (TMB-I) or low (TMB-L).
188 immunotherapy-treated (83.5% nivolumab, 11.7% pembrolizumab, 4.8% anti-PD1/PD-L1 plus anti-CTLA-4) pts with KRAS-mutant NSCLC were included in the efficacy analysis. The ORR differed significantly between the KL (8.8%), KP (35.9%) and K-only sub-groups (27.3%) (P=0.0011, Fisher’s exact test). KL LUAC exhibited significantly shorter PFS (mPFS 1.8m vs 2.7m, HR=0.53, 95% CI 0.34-0.84, P<0.001, log-rank test) and OS (mOS 6.8m vs 15.6m, HR 0.53, 95% CI 0.34 to 0.84, P=0.0072, log rank test) compared to KRAS-mutant NSCLC with wild-type STK11. Loss-of function (LOF) genetic alterations in STK11 were the only significantly enriched event in PD-L1 negative, TMB-I/H compared to PD-L1 high positive (TPS≥50%), TMB-I/H tumors in the overall FMI cohort (Bonferroni adjusted P=2.38x10[-4], Fisher’s exact test) and among KRAS-mutant tumors (adjusted P=0.05, Fisher’s exact test) . Notably, PD-1 blockade demonstrated activity among 10 PD-L1-negative KP tumors, with 3 PRs and 4SDs recorded. In syngeneic isogenic murine models PD-1 blockade significantly inhibited the growth of Kras mutant tumors with wild-type LKB1 (K), but not those with LKB1 loss (KL), providing evidence that LKB1 loss can play a causative role in promoting PD-1 inhibitor resistance.
Loss of function genomic alterations in STK11 represent a dominant driver of de novo resistance to PD-1/PD-L1 blockade in KRAS-mutant NSCLC. In addition to tumor PD-L1 status and tumor mutational burden precision immunotherapy approaches should take into consideration the STK11 status of individual tumors.
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P1.03 - Chemotherapy/Targeted Therapy (ID 689)
- Event: WCLC 2017
- Type: Poster Session with Presenters Present
- Track: Chemotherapy/Targeted Therapy
- Presentations: 1
- Coordinates: 10/16/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)
P1.03-028 - A Phase II Trial of Albumin-Bound Paclitaxel and Gemcitabine in Patients with Untreated Stage IV Squamous Cell Lung Cancers (ID 8556)
09:30 - 16:00 | Author(s): A. Plodkowski
Therapeutic options for squamous cell lung cancer (SQCLC) patients remain limited. Platinum-based chemotherapies, which have been the standard first-line treatments for nearly 20 years, are associated with ORR=30-40%, median PFS=4-5.7mo, and median OS=9-11.5mo. We previously reported the results of a phase 1/2 trial of albumin-bound paclitaxel (ABP) in 40 patients with untreated stage IV NSCLC, noting an ORR of 30%, median PFS of 5mo, and median OS of 11mo (Rizvi JCO 2008). These data suggest that platinum adds little when coupled to ABP. Conversely, compelling evidence of anti-tumor synergy between gemcitabine and ABP was recently demonstrated by Frese et al. who showed that ABP downregulates cytidine deaminase (which inactivates gemcitabine), leading to increased intratumoral [gemcitabine] (Cancer Disc 2012). Based on these data, we sought to assess the efficacy of ABP + gemcitabine in patients with SQCLC.
This is a phase II trial of ABP (100mg/m) + gemcitabine (1000mg/m) given on D1, D8, D15 of an every 4 week cycle (A1) in patients with untreated stage IV SQCLC. Patients received up to 6 cycles and were followed thereafter (A1). The primary endpoint is best objective response (RECIST 1.1). The study utilizes a Simon two-stage design with H0=25% (6/17 responses) and H1=45% (16/41 responses). After clearing the first stage, the study was amended to a 3 week cycle (D1, D8 treatment); to allow ABP + gemcitabine until progression; and to allow maintenance ABP to begin after C4 for tolerability (A2). PFS, TTP, and OS were calculated using the Kaplan-Meier method. Patients underwent NGS by MSK-IMPACT for genotype-phenotype correlation.
N=17 patients (14 evaluable) were treated on A1 and, to date, N=3 patients (2 evaluable) have been treated on A2. Median age=70, female=30%, median KPS=90%, smokers=90%, median pack years=32. Median cycles of therapy in A1=4. Grade ≥3 related AEs included: peripheral neuropathy (5%); diarrhea (5%); elevated ALT (5%); anemia (15%); and decreased neutrophils (25%). Three patients (15%) experienced a related SAE including G3 decreased WBC, G3 diarrhea, and G3 lung infection. There was 1 unrelated death as a result of complications from a G3 mechanical fall. ORR in A1=50% (7/14 PRs). ORR in A2=100% (2/2 PRs). ORR in A1+A2=56% (9/16 PRs). SD=6 (38%) and PD=1 (6%). Median PFS=5.8mo; TTP=6.9mo; OS=13.3mo.
ABP + gemcitabine has promising efficacy and is relatively well-tolerated, particularly when compared to platinum regimens. Accrual to the study is ongoing and updated data, including NGS correlates, will be presented.