Appendix e-1
Outcome analysis
Correlation of survival with steroid use
The majority of patients (n=23, 74%) received steroids at some time point while receiving anti- PD-1 therapy and 12 patients (39%) received dexamethasone ≥ 4 mg per day. There was no
significant difference in mPFS survival in patients who received steroids during anti-PD-1 therapy (mPFS=3.3 months, 95% CI 1.7, 4.8) compared to those that did not receive steroids (mPFS=1.5 months, 95% CI 0.1, 3; Log Rank [mPFS]=1.5, p=0.2). Similarly, there was no difference in mPFS depending on whether patients received dexamethasone ≥4 mg/day
(mPFS=3.5 months, 95% CI 3, 4) or <4 mg/day (mPFS=2.3 months, 95% CI 2.2, 2.3; Log Rank [mPFS]=0.2 p=0.6).
Correlation of survival with volumetric tumor assessment
We also evaluated the correlation of survival with tumor volume prior to initiation of anti-PD-1 blockade. Tumor volumetric data were available for 30/31 patients. Manual volumetric
segmentation of tumor on gadolinium-enhanced T1-weighted imaging was performed by a post- doctoral research fellow using 3D Slicer (www.slicer.org)1 and edited by a neuroradiologist to manually add pixels for tumor regions not included in the preliminary contour or remove pixels for non-tumor regions such as surgical scars that were included in the preliminary contour. The tumor volumes (in cubic centimeters, cm3) were calculated by multiplying the total pixel counts with pixel volume.
The median tumor volume prior to begin of nivolumab or pembrolizumab was 23.2 cm3 (range 2.1 – 142.3 cm3). There was no significant correlation between tumor volume and PFS (Pearson correlation coefficient -0.2, p=0.3) or survival from first PD-1 dose (Pearson correlation
coefficient -0.16, p=0.4).
Description of selected cases
Two patients (6%) were considered to have a hypermutator phenotype on repeat pathological tumor evaluation.
One of these patients had originally been diagnosed with an IDH-1 R132H mutant WHO II astrocytoma and was treated with resection, radiation and 12 monthly cycles of temozolomide.
He experienced pathologically confirmed tumor recurrence with transformation to a WHO IV glioblastoma ten years after initial diagnosis. Next generation sequencing analysis confirmed presence of the previously known mutations in IDH-1 R132H and TP53 A159V and identified 96 additional somatic mutations. Treatment with pembrolizumab was initiated and the patient progressed after 3.7 months. Subsequently the patient received CCNU and bevacizumab therapy.
The patient’s overall survival from time of glioblastoma diagnosis was 137 months and survival from first pembrolizumab dose was 12.7 months, respectively.
The other patient had originally been diagnosed with an IDH-1 R132C mutant WHO II astrocytoma and had received resection and 12 cycles of dose-dense temozolomide (50
mg/m2/d). The tumor recurred three years after the initial diagnosis and repeat biopsy revealed transformation to a WHO III anaplastic astrocytoma. Next generation sequencing analysis
confirmed presence of the previously known mutations in IDH-1 R132C and TP53 I195T and identified 15 additional somatic mutations. He subsequently received radiation with concurrent followed by six monthly cycles of temozolomide before clinical and radiographic disease progression. At that time, treatment with pembrolizumab was initiated but the patient had rapid clinical deterioration and progressed after a single dose of pembrolizumab (PFS=0.6 months).
Overall survival from time of diagnosis as an anaplastic astrocytoma was 53.3 months and survival from first PD-1 dose was 1.1 months.
A third patient appeared to have an unusual long-term response to treatment with nivolumab and received a total of 38 doses. This patient was initially diagnosed with a tectal WHO IV
glioblastoma (IDH-1/-2 not mutated, MGMT promoter unmethylated). Next generation sequencing analysis did not reveal any further mutations of known clinical significance. The patient was treated with radiation and concurrent temozolomide followed by six months of adjuvant temozolomide. Clinical and radiographic disease progression occurred 18 months after initial diagnosis and at that time, treatment with bevacizumab and nivolumab was initiated. The patient received 38 doses of pembrolizumab before tumor progression (PFS=19.6 months) and then died shortly afterwards (survival from first PD-1 dose=20.1 months). Given his tumor location, he did not have a second tissue evaluation and therefore the molecular phenotype at time of recurrence is not known.
Supplemental Reference
1. Fedorov A, Beichel R, Kalpathy-Cramer J, et al. 3D Slicer as an image computing platform for the Quantitative Imaging Network. Magn Reson Imaging. Nov 2012;30(9):1323-1341.
