"phase IIa study" is correct and usable in written English.
It is commonly used in medical and scientific writing to describe a specific type of clinical trial or research study. Example: The results of the phase IIa study showed promising efficacy for the new drug in treating patients with advanced cancer.
A selective ETA antagonist (clazosentan) was shown to decrease the frequency and severity of vasospasm in a preliminary phase IIa study [81].
Centrally acting noradrenaline reuptake inhibitor (NRI) is reportedly effective for patients with stress urinary incontinence (SUI) by increasing urethral closure in the clinical Phase IIa study with esreboxetine.
An impressive result with 82% ORR with a 55% CR rate was shown in the phase IIa study of 11 patients with refractory or relapsed CD20+ B-NHL (8 DLBCL, 1 FL, 1 MCL, and 1 primary cutaneous marginal zone lymphoma (PCMZL)) who were treated with the same protocol (Zhang et al., 2016a).
While the actual cause of the adverse events is unknown, speculation has centered on autoreactive cellular immune responses specific for the T-cell epitope in Aβ, or possibly the adjuvant, and/or the reformulation of the vaccine during the Phase IIa study [9], [10], [12], [13], [16].
In an international Phase IIa study of a three-injection DNA plasmid priming series followed by a single boost with VRC-HIVADV014-00-VP (HVTN study 204), T-cell responses to Env and Gag peptides were seen in approximately half of participants, twice as many as responded to Pol [35].
35 There are some limitations of this phase IIa study.
The aims of the observational, early phase IIa studies are usually several in number and often competing, and therefore the priorities should be clearly defined.
To further verify the potential metabolic benefits of GFT505, we conducted two phase IIa studies in patients with either combined dyslipidemia or prediabetes.
A pharmacokinetic-pharmacodynamic disease model which predicted in-vivo antiviral activity of maraviroc was used to assist dosage selection for clinical phase IIa studies (Rosario et al. 2005).
These two phase IIa studies provide the first clinical evidence that the use of the dual PPARα/δ agonist GFT505 improves multiple metabolic parameters in abdominally obese patients with either combined dyslipidemia or prediabetes.
This is followed by confirmation of the safety and pharmacodynamics/target engagement as well as, if feasible, initial evidence of clinical efficacy in phase IIA studies in relatively small groups of patients.
