Back to the future – Is the drug repositioning concept applicable to vaccines?

Travel vaccines are strongly associated to reduced mortality in prostate cancer patients - a real effect or residual confounding?

Repurposing of existing drugs and vaccines for diseases that they were not originally intended for is a promising research field. Recently there has been evidence that oral cholera vaccine might be used in the treatment of inflammatory disease and some common cancers. Specifically, Ji et al showed that the administration of cholera vaccine after a prostate cancer diagnosis reduced prostate cancer specific mortality rates by almost 50%. In a cohort of men from Stockholm, Sweden, with more detailed cancer data and a higher coverage of exposure to vaccine, we replicated these findings using a marginal structural Cox model. We showed that administration of cholera vaccine after prostate cancer diagnosis is associated with a significant reduction in mortality (HR 0.46, 95% CI 0.31-0.69, p-value 0.0001) even after adjusting for all known confounders. However, the same effect (or even stronger) could be seen for several other traveling vaccines and malaria prophylaxis. Therefore, we conclude that this effect is most likely due to a healthy traveler bias and is an example of residual confounding.

Transcriptome-Guided Drug Repositioning

Drug repositioning can save considerable time and resources and significantly speed up the drug development process. The increasing availability of drug action and disease-associated transcriptome data makes it an attractive source for repositioning studies. Here, we have developed a transcriptome-guided approach for drug/biologics repositioning based on multi-layer self-organizing maps (ml-SOM). It allows for analyzing multiple transcriptome datasets by segmenting them into layers of drug action- and disease-associated transcriptome data. A comparison of expression changes in clusters of functionally related genes across the layers identifies "drug target" spots in disease layers and evaluates the repositioning possibility of a drug. The repositioning potential for two approved biologics drugs (infliximab and brodalumab) confirmed the drugs' action for approved diseases (ulcerative colitis and Crohn's disease for infliximab and psoriasis for brodalumab). We showed the potential efficacy of infliximab for the treatment of sarcoidosis, but not chronic obstructive pulmonary disease (COPD). Brodalumab failed to affect dysregulated functional gene clusters in Crohn's disease (CD) and systemic juvenile idiopathic arthritis (SJIA), clearly indicating that it may not be effective in the treatment of these diseases. In conclusion, ml-SOM offers a novel approach for transcriptome-guided drug repositioning that could be particularly useful for biologics drugs.

What patents tell us about drug repurposing for cancer: A landscape analysis

Intellectual property documents (patents and their published applications) are not only collections of legal exclusivity claims but also repositories of scientific and technical information, even though they are not peer reviewed. We have identified and analyzed international disclosures concerning drug repurposing for cancer that were published under the Patent Convention Treaty during the past five years, and show this burgeoning field from an angle that is not routinely captured in review papers of the field. We find that patenting activity for cancer-related new uses for known compounds has been quite constant recently and has targeted mainly small molecule active ingredients that are currently marketed as drugs. Universities contributed most applications, closely followed by corporations. The strong representation of non-academic research institutes from the public and private sector and foundations was surprising and indicates that drug repurposing for cancer has transcended the classical corporate-academia dichotomy. Many of the identified patent documents report findings that are not reflected in the peer review literature (e.g., sumatriptan for mycosis fungoides) or appear there only later (e.g., ibudilast for glioblastoma). Synergistic combinations of several repurposed compounds were also identified, as were two documents related to the repurposing of vaccines. Our findings underscore the necessity for drug repurposers as well as for oncologists to investigate patent documents in addition to the usual peer review literature search to obtain a comprehensive perspective of the state of the art.