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Significant Inputs and Assumptions Used in Binomial Lattice Model for Derivative Liability (Detail)

v3.6.0.2
Significant Inputs and Assumptions Used in Binomial Lattice Model for Derivative Liability (Detail) - $ / shares
6 Months Ended
Sep. 15, 2016
Jun. 23, 2015
May 31, 2015
Apr. 30, 2015
Feb. 06, 2015
Sep. 26, 2014
Nov. 30, 2016
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]              
Contractual conversion rate $ 0.78           $ 0.67
Adjusted conversion price       $ 0.675      
Contractual term to maturity (years) 5 years           4 years 9 months 15 days
Expected volatility 106.00%           103.00%
Risk-free rate 1.20%           1.81%
Derivative Liability              
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]              
Quoted market price on valuation date   $ 0.90 $ 0.99   $ 0.96 $ 0.79  
Contractual conversion rate   1.00 1.00   1.00 1.00  
Adjusted conversion price [1]   $ 0.6750 $ 0.6750   $ 1.0000 $ 0.9759  
Contractual term to maturity (years)   1 month 13 days     5 months 27 days 2 years  
Expected volatility   48.00%     124.00% 123.00%  
Contractual interest rate   1.20%     2.00% 5.00%  
Risk-free rate   0.001%     0.045% 0.59%  
Risk adjusted rate   2.80% 2.80%   2.78% 2.69%  
Probability of event of default   5.00% 5.00%   5.00% 5.00%  
Derivative Liability | Minimum              
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]              
Contractual term to maturity (years)     2 months 5 days        
Expected volatility     90.00%        
Contractual interest rate     1.50%        
Risk-free rate     0.041%        
Derivative Liability | Maximum              
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]              
Contractual term to maturity (years)     1 year 3 months 29 days        
Expected volatility     114.00%        
Contractual interest rate     5.00%        
Risk-free rate     0.48%        
[1] The adjusted conversion price input used in the Binomial Lattice Model considers both (i) the reduction of the conversion price to $0.675 on April 30, 2015, as result of a private placement offering in which Common Stock was sold for a weighted average price of $0.75 and (ii) potential adjustment to the stated conversion price due to a future dilutive issuance. This input was calculated using a probability-weighted approach which considered the likelihood of various scenarios occurring including (i) potential success or failure of various phases for PRO 140, (ii) the probability the Company will enter into a future financing and (iii) and the potential price of a future financing.