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Developing new, effective pharmaceutical compounds is a fundamentally 
difficult task.
Starting with challenges identifying promising treatment targets and potential 
compounds to ensuring the drug can be properly delivered within the body, the 
scientific work that needs to succeede is massive.
The regulatory and market conditions in which they exist add to this difficulty. 
For example, regulations are designed to reduce the number of drugs released 
to market with significan issues, such as in the case of VIOXX 
\cite{krumholz_whathavewe_2007} 
or the Perdue Pharma scandal 
\cite{officepublicaffairsjusticedepartment_2020}.
These regulations, such as clinical trial standards 
\todo{add citation to clinical trials here}, 
increase the costs of developing new drugs, adding to the business concerns 
already present, including competitors already in the market or close to 
entering and the overall demand to address a given condition.

%begin discussing failures
%I am thinking I'll discuss marketing and operational failures
%I somehow need to step away from the drug development framing and soften it to 
%... what? drug investigation?
From these general challenges we can begin to classify failures in drug 
development into a hierarchy of causes.
\cite{khmelnitskaya_competitionattritiondrug_2021}
described two general causes for a drug to exit the drug-development pipline,
strategic exits and scientific failure.
Similarly
\cite{hwang_failure_2016} 
ascribe failues of Phase III trials to issues with safety, 
efficacy, or other (buisness) concerns.


% The only one most ameniable to being targeted by policy 
% is those ``other concerns''.
Although decisions to continue drug development are driven 
by long term profit analyses,
pharmaceutical companies face short term operational challenges
which can impede the development process. 
Some operational reasons given for why a trial was stopped include: 
\begin{itemize}
    \item Organizational challenges (Principle Investigator left institution, 
        changes in research focus, staff shortages)
    \item Troubles with recruitment, (accural to slow/low, difficulty locating 
        qualified participants, etc).
    \item Changes in standards of care.
    \item Sponsor withdraws support or provides insufficient financial support,
        e.g Funding runs out.
    \item Beginning or end of a pandemic.
\end{itemize}
% As an example, while a drug may have few competitors and 
% strong evidence of safety, difficulties recruiting trial participants may 
% prevent the clinical trials process from being completed successfully.
Thus being able to isolate the effect of specific operational challenges from 
strategic decisions allows us to more accurately predict the intended or 
unintended effects of a given policy on clinical trials.

In this work, I focus on separating the effects of enrollment and 
competing drugs on clinical trial completion, specifically Phase III trials.
To do this, I create a dataset extracted from 
\url{ClinicalTrials.gov} 
that tracks individual clinical trials as they progress towards completion. 
I also introduce a novel causal model of individual clinical trial progression.
Unlike previous research which generally focuses on the drug development 
pipeline through multiple phases, I restrict my investigation to modelling 
individual clinical trials.
This restriction provides a way to separate the impact of different operational
changes, specifically enrollment troubles and changes in the market.

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