Successful cancer therapies are often based on drug combinations to halt cancer growth and prevent resistance mechanisms. A good way to find novel, unexpected synergistic drug combinations is unbiased high throughput screening on cancer cell lines, such as the NTRC SynergyScreen™ platform. The effort involved in handling large numbers of possible combinations may constrain broad screening. NTRC therefore launches two additions to its SynergyScreen™ platform: diversity-based library screening and in silico prioritization.
In diversity-based screening, the drug of interest is screened in combination with a set of 43-exemplars that were selected from a library of 162 therapeutics [1]. The library represents the known variety of anti-cancer mechanisms under investigation and approved for clinical use (Figure 1). Only if synergistic hits are found for an exemplar, the other compounds from the exemplar’s cluster are screened in a second step. In an example for the PARP inhibitor niraparib, screening of 50% less compounds identified more than 70% of the validated synergistic hits from the broad screen.
In the in silico prioritization workflow, the Oncolines™ drug responses of the compound of interest are combined with known clinically validated synthetic lethal interactions [2], to generate a list of likely synergistic partners for the single agent. This list is then prioritized for actual combination screening. The in silico prioritization workflow was highly succesful in predicting synergistic pairs that are reported in the combination screening literature, and in NTRC internal screens.
The new technologies will be presented at the American Association of Cancer Research meeting in Atlanta, April 1st, abstract no. 2158.

Figure 1: Anti-cancer mechanisms and their exemplars (red dots).

Literature references
1. Uitdehaag et al. (2016) Mol Cancer Ther 15, 3097-3109.
2. Lee et al. (2018) Nature Communications, 9, 2546..