MiSTIC stands for Minimum Spanning Trees Inferred Clustering
Here is the full citation : Lemieux S., Sargeant T., Laperrière D., Ismail H., Boucher G., Rozendaal M., Lavallée V-P., Ashton-Beaucage D., Wilhelm B., Hébert J., Hilton DJ., Mader S., Sauvageau G.; MiSTIC, an integrated platform for the analysis of heterogeneity in large tumour transcriptome datasets, Nucleic Acids Research, Volume 45, Issue 13, 27 July 2017, Pages e122, https://doi.org/10.1093/nar/gkx338
Yes, the code is openly available. The "frozen" version of the code that is associated with the paper can be found on GitHub whereas the latest version can be found on gitlab.iric.ca.
Start on the Data page
You can watch the help video on youtube or below.
The video will give you an idea of how you can use MiSTIC