Activity of Entrectinib in a Patient With the First Reported NTRK Fusion in Neuroendocrine Cancer.

Despite advances in genomic analysis, the molecular origin of neuroendocrine tumors (NETs) is complex and poorly explained by described oncogenes. The neurotrophic TRK family, including NTRK1, 2, and 3, encode the proteins TRKA, TRKB, TRKC, respectively, involved in normal nerve development. Because NETs develop from the diffuse neuroendocrine system, we sought to determine whether NTRK alterations occur in NETs and whether TRK-targeted therapy would be effective. A patient with metastatic well-differentiated NET, likely of the small intestine, was enrolled on the STARTRK2 trial (ClinicalTrials.gov identifier: NCT02568267) and tissue samples were analyzed using an RNA-Seq next-generation sequencing platform. An ETV6:NTRK3 fusion was identified and therapy was initiated with the investigational agent entrectinib, a potent oral tyrosine kinase inhibitor of TRKA, TRKB, and TRKC. Upon treatment with entrectinib, the patient experienced rapid clinical improvement; his tumor response was characterized by initial tumor growth and necrosis. This is the first report of an NTRK fusion in NETs. Our patient's response to entrectinib suggests that NTRK fusions can be important in the pathogenesis of NETs. Recent DNA-based genomic analyses of NETs may have missed NTRK fusions due its large gene rearrangement size and multiple fusion partners. The tumor's initial pseudoprogression may represent a unique response pattern for TRK-targeted therapies. An effort to characterize the prevalence of NTRK fusions in NETs using optimal sequencing technology is important.

Safety and Antitumor Activity of Apalutamide (ARN-509) in Metastatic Castration-Resistant Prostate Cancer with and without Prior Abiraterone Acetate and Prednisone.

Purpose: To evaluate the efficacy of apalutamide before or after treatment with abiraterone acetate and prednisone (AAP) in patients with progressive metastatic castration-resistant prostate cancer (mCRPC).Experimental Design: Two cohorts were studied: AAP-naïve and post-AAP patients who had received ≥6 months of AAP. Patients had progressive mCRPC per rising prostate-specific antigen (PSA) and/or imaging, without prior chemotherapy exposure. All received apalutamide 240 mg/day. Primary endpoint was ≥50% decline in 12-week PSA according to Prostate Cancer Working Group 2 criteria. Secondary endpoints included time to PSA progression and time on treatment.Results: Forty-six patients enrolled in the AAP-naïve (n = 25) and post-AAP (n = 21) cohorts. The 12-week PSA response rate was 88% (22/25) and 22% (4/18), median time to PSA progression was 18.2 months [95% confidence interval (CI), 8.3 months-not reached) and 3.7 months (95% CI, 2.8-5.6 months), and median time on treatment 21 months (range, 2.6-37.5) and 4.9 months (range, 1.3-23.2), for the AAP-naïve and post-AAP cohorts, respectively. Eighty percent (95% CI, 59-93) and 64% (95% CI, 43-82) of AAP-naïve and 43% (95% CI, 22-66) and 10% (95% CI, 1-30) of post-AAP patients remained on treatment for 6+ and 12+ months, respectively. Common treatment-emergent adverse events in both cohorts were grade 1 or 2 fatigue, diarrhea, nausea, and abdominal pain.Conclusions: Apalutamide was safe, well tolerated, and demonstrated clinical activity in mCRPC, with 80% of AAP-naïve and 43% of post-AAP patients, remaining on treatment for 6 months or longer. Clin Cancer Res; 23(14); 3544-51. ©2017 AACR.

A clinically relevant androgen receptor mutation confers resistance to second-generation antiandrogens enzalutamide and ARN-509.

UNLABELLED: Despite the impressive clinical activity of the second-generation antiandrogens enzalutamide and ARN-509 in patients with prostate cancer, acquired resistance invariably emerges. To identify the molecular mechanisms underlying acquired resistance, we developed and characterized cell lines resistant to ARN-509 and enzalutamide. In a subset of cell lines, ARN-509 and enzalutamide exhibit agonist activity due to a missense mutation (F876L) in the ligand-binding domain of the androgen receptor (AR). AR F876L is sufficient to confer resistance to ARN-509 and enzalutamide in in vitro and in vivo models of castration-resistant prostate cancer (CRPC). Importantly, the AR F876L mutant is detected in plasma DNA from ARN-509-treated patients with progressive CRPC. Thus, selective outgrowth of AR F876L is a clinically relevant mechanism of second-generation antiandrogen resistance that can potentially be targeted with next-generation antiandrogens. SIGNIFICANCE: A missense mutation in the ligand-binding domain of the androgen receptor F876L confers resistance to the second-generation antiandrogens enzalutamide and ARN-509 in preclinical models of AR function and prostate cancer and is detected in plasma DNA from ARN-509-treated patients with progressive disease. These results chart a new path for the discovery and development of next-generation antiandrogens that could be coupled with a blood-based companion diagnostic to guide treatment decisions.

Phase II study of sunitinib administered in a continuous once-daily dosing regimen in patients with cytokine-refractory metastatic renal cell carcinoma.

PURPOSE: Sunitinib has demonstrated antitumor activity in metastatic renal cell carcinoma (mRCC) when given at 50 mg/d on a 4-weeks-on 2-weeks-off regimen. Herein, we report results of an open-label, multicenter phase II mRCC study of sunitinib administered on a continuous once-daily dosing regimen. PATIENTS AND METHODS: Eligibility criteria included histologically proven mRCC with measurable disease, failure of one prior cytokine regimen, and good performance status. Patients were randomly assigned to a sunitinib starting dose of 37.5 mg/d in the morning (AM) or evening (PM). RECIST-defined objective response rate (ORR) was the primary end point. Secondary end points included progression-free survival (PFS), overall survival (OS), adverse events (AEs), and quality-of-life measures. RESULTS: One hundred seven patients were randomly assigned to AM (n = 54) or PM (n = 53) dosing and on study for a median 8.3 months. Eighty-three patients discontinued, 65 due to disease progression and 16 because of AEs; two patients withdrew consent. Dosing was reduced to 25 mg/d in 46 patients (43%) due to grade 3/4 AEs. The most common grade 3 treatment-related AEs were asthenia/fatigue (16%), diarrhea (11%), hypertension (11%), hand-foot syndrome (9%), and anorexia (8%). ORR was 20% with a 7.2-month median response duration. Median PFS and OS were 8.2 and 19.8 months, respectively, at median follow-up of 26.4 months. Efficacy, tolerability, and quality-of-life results were similar between patients dosed in the AM or PM. CONCLUSION: Sunitinib 37.5 mg, administered on a continuous once-daily dosing regimen, has a manageable safety profile as second-line mRCC therapy, providing flexible dosing, which can be explored in combination studies.