McRee, Autumn J.

519 Background: KRAS, the most frequently mutated oncogene in cancer, is a key mediator of the RAS/MAPK signaling cascade that promotes cellular growth and proliferation. KRAS mutations occur in approximately 90% of pancreatic cancer, and approximately 2% of these are KRASG12C mutations. Adagrasib, an investigational agent, is a KRASG12C inhibitor that irreversibly and selectively binds KRASG12C, locking it in its inactive state; adagrasib has been optimized for favorable pharmacokinetic (PK) properties, including long half-life (̃24 h), extensive tissue distribution, dose-dependent PK, as well as CNS penetration. Methods: KRYSTAL-1 (NCT03785249) is a multicohort Phase 1/2 study evaluating adagrasib as monotherapy or in combinations in pts with advanced solid tumors harboring a KRASG12C mutation. Here we report preliminary data from pts enrolled in a Phase 2 cohort evaluating single-agent adagrasib administered orally at 600 mg BID in previously treated pts with unresectable or metastatic solid tumors (excluding NSCLC and CRC), including pancreatic and other GI cancers. Study endpoints include clinical activity, safety, and PK. Results: The data cutoff was 10 September 2021. A total of 42 pts were enrolled in this cohort (median age 63.5 years, range 21–89; 52% female; 71% white; 29%/71% ECOG PS 0/1; median 2 prior lines of therapy, range 1–7; median follow-up 6.3 months), of whom 30 pts had KRASG12C-mutant GI tumors (12 PDAC, 8 biliary tract, 5 appendiceal, 2 gastro-esophageal junction, 2 small bowel, and 1 esophageal). In a preliminary analysis, 27 pts with GI tumors were evaluable for clinical activity; partial responses (PRs) were seen in 41% (11/27, including 3 unconfirmed PRs); the disease control rate (DCR) was 100% (27/27). Of the 12 pts with PDAC (median 3 prior lines of therapy; median follow-up 8.1 months), 10 were evaluable for clinical activity; PRs were seen in 50% (5/10, including 1 unconfirmed PR); the DCR was 100% (10/10). Median progression-free survival (PFS) was 6.6 months (95% CI 1.0–9.7), and treatment was ongoing in 50% of pts with PDAC. Among the 17 evaluable pts with other GI tumors, 6 achieved PR (35%; 2 unconfirmed) with a DCR of 100% (17/17); 11 pts were still receiving treatment. In the overall cohort, treatment-related adverse events of any grade occurred in 91% (38/42), the most frequent being nausea (48%), diarrhea (43%), vomiting (43%), and fatigue (29%); grade 3/4 events occurred in 21% of pts, with no grade 5 events. Conclusions: Adagrasib monotherapy is well tolerated and demonstrates encouraging clinical activity in pretreated pts with PDAC and other GI tumors harboring a KRASG12C mutation. Further exploration of adagrasib is ongoing in this pt population (NCT03785249). Clinical trial information: NCT03785249.

116 Background: Constitutively activating KRAS or NRAS muts occur in ̃50% of CRC, increasing RAF-MEK-ERK signaling and causing overexpression of cyclin D1, which binds to cyclin dependent kinase 4/6 (CDK4/6) to drive cell cycle progression. Combination MEK and CDK4/6 inhibitors caused tumor regression in patient-derived xenografts of KRAS mut CRC. We hypothesized that binimetinib and palbociclib (B+P) would improve progression-free survival (PFS) compared to TAS-102 in refractory KRAS/NRAS mut mCRC. Methods: ACCRU-GI-1618 was a multicenter, randomized phase II clinical trial (NCT03981614). Key inclusion criteria were KRAS/NRAS mut mCRC, with prior fluoropyrimidine/ oxaliplatin/ irinotecan/ anti-VEGF therapy. There was a 6-patient safety run-in with binimetinib 30 mg po BID D1-28 and palbociclib 100 mg po daily D1-21. After, patients were randomized 1:1 to B+P vs TAS-102 (stratified by KRAS mut type and prior regorafenib use), with optional crossover at progression. The primary endpoint was PFS; 73 PFS events (from a sample size of 112) provided 90% power to detect improvement of PFS (hazard ratio = 0.5, i.e. median PFS of 2 vs. 4 months) with 1-sided α = 0.05. A prespecified interim analysis for futility was planned after 37 PFS events were observed, with completion of accrual if 1-sided stratified log-rank p-value < 0.551. Hazard ratios (HR) and 95% confidence intervals (CI) are estimated by stratified Cox proportional hazards models. Results: After the safety run-in, 93 patients at 6 sites were randomized; 82 (41 B+P, 41 TAS-102) comprise the primary analysis population (eligible, consented, and started treatment). In this population, median age was 52 years, 50% female, 68% left-sided, 79% with KRAS codon 12/13 mut, 12% with prior regorafenib. Enrollment was halted at interim analysis as the futility boundary was crossed (1-sided p = 0.67). At final analysis, 68 subjects had a PFS event (34 in each arm). Median PFS was 2.1 mo (95% CI 2.0-3.0) with B+P vs 2.1 mo (2.0-2.4) with TAS-102; HR 0.86 (0.52-1.44). 4-mo PFS rate was 22.2% (11.9-41.6) with B+P vs 10.6% (3.8-30.0) with TAS-102. With 37 OS events (14 in B+P arm), median OS was 7.7 mo (5.1-NE) with B+P vs 6.6 mo (4.8-8.9) with TAS-102; HR 0.77 (95% CI 0.39-1.51). TAS-102 had greater grade 3-4 hematologic AEs (46% vs 22%), and B+P had more grade 3-4 non-hematologic AEs (47% vs 32%). Grade 3-4 AEs more common with B+P were fatigue (8% vs 0%), oral mucositis (6% vs 0%), and nausea (4% vs 2%). Though 63% of patients on B+P had acneiform rash, only 2% was grade 3-4. Grade 1-2 diarrhea occurred in 35% of B+P and 24% of TAS-102 patients. No new safety signal was observed. Conclusions: B+P did not significantly improve median PFS or OS compared to TAS-102 in KRAS/NRAS mut mCRC. Subgroup analyses and translational studies are ongoing to determine which subgroups may be more likely to attain 4-mo PFS or identify mechanisms of resistance. Clinical trial information: NCT03981614.

Background Human telomerase reverse transcriptase (hTERT) is frequently classified as a ‘universal’ tumor associated antigen due to its expression in a vast number of cancers. We evaluated plasmid DNA-encoded hTERT as an immunotherapy across nine cancer types. Methods A phase 1 clinical trial was conducted in adult patients with no evidence of disease following definitive surgery and standard therapy, who were at high risk of relapse. Plasmid DNA encoding one of two hTERT variants (INO-1400 or INO-1401) with or without plasmid DNA encoding interleukin 12 (IL-12) (INO-9012) was delivered intramuscularly concurrent with the application of the CELLECTRA constant-current electroporation device 4 times across 12 weeks. Safety assessments and immune monitoring against native (germline, non-mutated, non-plasmid matched) hTERT antigen were performed. The largest cohort of patients enrolled had pancreatic cancer, allowing for additional targeted assessments for this tumor type. Results Of the 93 enrolled patients who received at least one dose, 88 had at least one adverse event; the majority were grade 1 or 2, related to injection site. At 18 months, 54.8% (51/93) patients were disease-free, with median disease-free survival (DFS) not reached by end of study. For patients with pancreatic cancer, the median DFS was 9 months, with 41.4% of these patients remaining disease-free at 18 months. hTERT immunotherapy induced a de novo cellular immune response or enhanced pre-existing cellular responses to native hTERT in 96% (88/92) of patients with various cancer types. Treatment with INO-1400/INO-1401±INO-9012 drove hTERT-specific IFN-γ production, generated hTERT-specific CD4+ and CD8+ T cells expressing the activation marker CD38, and induced hTERT-specific activated CD8 +CTLs as defined by cells expressing perforin and granzymes. The addition of plasmid IL-12 adjuvant elicited higher magnitudes of cellular responses including IFN-γ production, activated CD4+ and CD8+ T cells, and activated CD8+CTLs. In a subset analysis of pancreatic cancer patients, the presence of immunotherapy-induced activated CD8+ T cells expressing PD-1, granzymes and perforin correlated with survival. Conclusions Plasmid DNA-encoded hTERT/IL-12 DNA immunotherapy was well-tolerated, immune responses were noted across all tumor types, and a specific CD8+ phenotype increased by the immunotherapy was significantly correlated with survival in patients with pancreatic cancer.