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Keywords:

  • lung cancer;
  • nonsmall cell lung cancer;
  • chemoprevention;
  • enzastaurin;
  • protein kinase C-β;
  • glycogen synthase kinase 3β;
  • Ki-67;
  • caspase 3;
  • apoptosis;
  • biomarkers.

Abstract

BACKGROUND:

Chemoprevention for lung cancer with nutraceutical or anti-inflammatory agents has had mixed clinical benefit. Novel targeted agents hold the promise of greater efficacy and selectivity. The authors of this report evaluated enzastaurin, a selective protein kinase C-β (PKC-β) inhibitor with antiproliferative and proapoptotic properties, in former smokers.

METHODS:

The primary objective of this study was to compare the average fraction of Ki-67–stained cells (the Ki-67 labeling index [LI]) in bronchial biopsy specimens that were collected before and after treatment. Participants were randomized (2:1) to receive either 6 months of daily oral enzastaurin (500 mg) or placebo. Stratification was based on morphology, history of lung cancer, and airway obstruction.

RESULTS:

In pretrial investigations, the rationale for PKC-β inhibition and pathway interrogation was established in premalignant lesions and early stage lung cancer. In an intent-to-treat analysis, of 40 randomized participants, there was no significant difference in the pretreatment/post-treatment change in the Ki-67 LI between the enzastaurin group and the placebo group (P = .53). Six participants discontinued enzastaurin, including 4 participants who had adverse events, including abdominal distension, deep vein thrombosis, hyponatremia, and rash, and 2 participants who decided to discontinue. One participant in the placebo group was discontinued on the study because of noncompliance. Two participants had ≥1 serious adverse event (bradycardia, deep vein thrombosis, and hypotension).

CONCLUSIONS:

To the authors' knowledge, this represents the first chemoprevention trial with a non-US Food and Drug Administration-approved, oral, small-molecule–targeted agent. Although the primary endpoint was not met, enzastaurin was tolerable for 6 months by 75% of participants, and there was a suggestion of response in a subset analysis that was restricted to those who had metaplastic or dysplastic lesions. Cancer 2013. © 2012 American Cancer Society.