Background: AP26113 is a novel orally-active tyrosine kinase inhibitor with preclinical activity against ALK and all 9 clinically-identified crizotinib-resistant mutants tested. Methods: The Phase (Ph) 2 portion of a Ph1/2 single arm, multicenter study in pts with advanced malignancies is underway. We report updated safety for all treated pts and efficacy data for ALK+ NSCLC pts previously treated with crizotinib. NCT01449461. Results: As of 16 Dec 2013, 114 pts were enrolled: 65 in Ph1 (30-300 mg) and 49 in Ph2 (180 mg). Baseline characteristics: 59% female, median age 57 yr; diagnoses: NSCLC n=106, other n=8. 66 pts remain on study; median follow-up for all pts is 3.6 mo (max= 21.4 mo, ongoing). The most common treatment-emergent AEs (≥20%) were nausea (38%), diarrhea (31%), fatigue (31%), cough (23%), and headache (20%), which were generally grade 1/2 in severity. Early onset of pulmonary symptoms (dyspnea with hypoxia and/or findings on imaging) observed in 6/45 (13%) pts at 180mg QD. These symptoms, requiring immediate medical attention, were not observed at 90mg QD (n=8) or in the lead-in dose cohort (n=19; initiated at 90mg QD, escalated to 180mg QD after 1 wk). Pts continue to be enrolled with this dose escalation scheme, and an additional cohort of 90mg QD without escalation will be added. Among 38 evaluable ALK+ NSCLC pts with prior crizotinib, 24 (63%) responded (23 partial response, 1 complete response). Duration of response was 1.6 - 14.7 mo (ongoing). 15 pts had confirmed responses; 5 await confirmation, 4 are unconfirmed. Among 42 evaluable pts with ALK+ NSCLC, median progression free survival is 47 wk. Independent radiological review conducted on 10 pts enrolled with untreated or progressing brain metastases showed 6/10 pts with response in brain, including 4 with undetectable brain metastases following AP26113; 2 pts had stable disease, 2 pts progressed; 8/10 remain on study (range 5-17 mo). Conclusions: AP26113 has promising anti-tumor activity in pts with crizotinib-resistant ALK+ NSCLC, including pts with brain metastases. A randomized Ph2 trial evaluating 90 mg QD vs. 90mg QD escalating to 180mg QD in crizotinib-resistant ALK+ NSCLC will begin shortly. Clinical trial information: NCT01449461.