I would like a list of drug-variant interactions (i.e. a variant for which its mutational status affects the efficacy of a particular drug).

I noticed that [nightly-ClinicalEvidenceSummaries.tsv][1] currently contains 593 drug-variant interactions (as of March 22, 2016). Is this the full list of all drug-variant interactions currently contained in the CIViC database? 

If so, great! Otherwise, it seems like the alternative is to use the API to obtain variant/evidence information and then parse the resulting JSON. Thanks.

  [1]: https://civic.genome.wustl.edu/#/releases
That sound right. The nightly TSV file should be a complete representation of the total number of evidence statements in CIViC. However, the level of detail is reduced compared to what you could get from the API. Also, I see that there are some formatting issues still occurring with the TSV file. We are working to fix this. However, the API is definitely recommended. 

Check out this set of python tools (under active development) that pulls CIViC data via the API in various ways. 
https://github.com/griffithlab/civic-api-client