Challenges and opportunities for the development of new antipsychotic drugs

In spite of the significant impact that the serendipitous discovery of drugs with antipsychotic properties had on the care of patients with psychotic disorders, there are significant challenges when aiming at therapeutic goals such as remission, recovery, improved health-related quality of life and functioning. The efficacy and effectiveness of existing antipsychotic drugs fail to address the full spectrum of symptoms and functional deficits that currently prevent patients with psychotic disorders from achieving fulfilling lives. The study of the pharmacological mechanism of action has increased our knowledge on molecular targets and brain circuits related to the antipsychotic properties of this drug class. However, our understanding of how these molecular targets and brain circuits relate to other aspects of disease pathophysiology like cognitive impairment and negative symptoms is incomplete although these are significant clinical unmet needs. Currently, there is still an important knowledge gap between psychopathology and pathophysiology in schizophrenia research. This may have contributed to some recent costly failures of large clinical development programs for drugs targeted at glutamatergic function and nicotinic receptors. The lack of success of these pharmacological approaches to achieve clinical validation raises important questions concerning the underlying hypothesis that guided the choice of molecular targets, and about the predictive validity of translational models that supported the rationale for testing these drugs in clinical studies. From a clinical perspective there is a need to more strongly consider the disease heterogeneity linked to the use of the current diagnostic classification of subjects and to the validity of the psychopathological constructs and assessments that are used to assess clinical outcomes. A paradigm shift in the development of drugs for schizophrenia is needed. This will require among other addressing: the shortcomings of a single diagnostic entity; the needs for in depth clinical phenotyping to leverage the findings of schizophrenia genetics and advance the understanding of the disease biology; the symptom domains that are the major sources of disability in order to improve functional outcomes beyond current treatment options. In spite of the progress achieved during the last century the task ahead is still daunting and will require the efforts of scientists and clinicians through inclusive public-private partnerships and consortia to create the scientific basis for new therapeutic approaches to schizophrenia.