Phase 1/2 trial of XPO1 inhibitor selinexor plus docetaxel in previously treated, advanced KRAS mutant non-small cell lung cancer

Abstract Purpose: Patients with KRAS mutant non-small cell lung cancer (NSCLC) have limited therapeutic options. Based on activity of nuclear export inhibition in preclinical models, we evaluated this strategy in previously treated advanced KRAS mutant NSCLC. Patients and Methods: The primary outcome of this multi-center phase 1/2 dose escalation trial of selinexor plus docetaxel was safety and tolerability. Selinexor was started one week before docetaxel to permit monotherapy pharmacodynamic assessment. Results: Among 40 enrolled patients, median age was 66 years, 55% were female, and 85% were white. Maximum tolerated dose was selinexor 60 mg orally weekly plus docetaxel 75 mg/m2 every three weeks. The most common adverse events were nausea (73%, 8% Gr ≥3), fatigue (70%, 5% Gr ≥3), neutropenia (65%, 60% Gr ≥3), and diarrhea (58%, 10% Gr ≥3). Of 32 efficacy evaluable patients, 7 (22%) had partial responses and 18 (56%) had stable disease. Outcomes were not associated with KRAS mutation type but were significantly better in cases with wild type TP53 (42%), including disease control and response rates (27% and 80%, vs. 9% and 27%, respectively; P=0.03) and progression-free survival (median 7.4 vs. 1.8 months; HR, 0.2; 95% CI, 0.07-0.67; P=0.003). Post-selinexor / pre-docetaxel, serum LDH levels increased an average 51 U/L in TP53 altered and decreased an average 48 U/L in TP53 wild type cases (P=0.06). Conclusions: Selinexor plus docetaxel was relatively well tolerated in patients with advanced KRAS mutant NSCLC. The regimen has promising efficacy in TP53 wild type cases, where selinexor monotherapy may also have activity.