Figure 2.

The radiotherapy sensitizing effect of Immunotherapy is compared between different studies: therefore tumor growth delay(TGD) was calculated and used to define the Radiation Enhancement factor (REF) between radiotherapy combined with immunotherapy and radiotherapy alone. The X axis displays the various classes of immunotherapies used in the studies: (1) anti-PD-(l)-1, (2) CTLA4, (3) cytokines: r-IL-2, (4) Vaccination / Dendritic cells, (5) CPG / Toll-like receptor, and (6) others. The Y-axis represents the value of the REF, from 0 to 90. The blue-dashed line is a REF value of 1, meaning RT + immunotherapy has the same effect as RT solely. Every dot represents a single calculated REF of one preclinical study. Several dots are calculated per study. A horizontal line represents the mean REF per immunotherapy. A green dot represents the calculated REF’s based on survival curves or on response rates: these are based on the volume of the last day of follow-up because the tumor was progression free. Therefore these dots are a minimal representation of the REF because in reality it concerns a higher REF