Diffuse intrinsic pontine gliomas (DIPG) at recurrence: is there a window to test new therapies in some patients?

Children with diffuse intrinsic pontine glioma (DIPG) need new and more efficient treatments. They can be developed at relapse or at diagnosis, but therefore they must be combined with radiotherapy. Survival of children after recurrence and its predictors were studied to inform the possibility to design early phase clinical trials for DIPG at this stage. Among 142 DIPG patients treated between 1998 and 2014, 114 had biopsy-proven DIPG with histone H3 status available for 83. We defined as long survivors' patients who survived more than 3 months after relapse which corresponds to the minimal life expectancy requested for phase I/II trials. Factors influencing post-relapse survival were accordingly compared between short and long-term survivors after relapse. Fifty-seven percent of patients were considered long survivors and 70% of them had a Lansky Play Scale (LPS) above 50% at relapse. Patients who became steroids-independent after initial treatment for at least 2 months had better survival after relapse (3.7 versus 2.6 months, p = 0.001). LPS above 50% at relapse was correlated with better survival after relapse (3.8 versus 1.8 months, p < 0.001). Patients with H3.1 mutation survived longer after relapse (4.9 versus 2.7 months, p = 0.007). Patients who received a second radiotherapy at the time of relapse had an improved survival (7.5 versus 4 months, p = 0.001). In the two-way ANOVA analysis, steroid-independence and LPS predicted survival best and the type of histone H3 (H3.1 or H3.3) mutated did not improve prediction. Survival of many DIPG patients after relapse over 3 months would make possible to propose specific trials for this condition. Steroid-independence, H3 mutation status and LPS should be considered to predict eligibility.