Abstract 1469
Background
Pem, an immune checkpoint inhibitor, has been demonstrated to be active in various neoplasms with MMRd. No data exist about its efficacy in MMRd glioma patients.
Methods
MMRd HGG patients relapsed after receiving RT and CT were treated with Pem. MMR status was analyzed by immunohistochemistry, including the MLH1, MSH2, MSH6, and PMS2 markers. MMR deficiency was defined as presence of a weak (wMMRd) or absent (aMMRd) signal on immunohistochemistry for at least one MMR protein. Other inclusion criteria were: ECOG PS 0-2, histologically confirmed gliomas, dexamethasone ≤4 mg. Pem was administered at 200 mg every 3 weeks until disease progression or unacceptable toxicity. Tumor response was evaluated by brain MRI every 10 weeks according to the RANO criteria. OS and PFS were evaluated by Kaplan-Meier curves. CTCAE v4.0 was used for toxicity assessment.
Results
Among 167 glioma patients, we found 22 MMRd gliomas. 12 PTS were treated with Pem: 8 wMMRd and 4 aMMRd. According to Bethesda criteria, all PTS had microsatellite stability. Tumor histologies included 5 anaplastic astrocytoma, 1 anaplastic oligodendroglioma, 6 glioblastoma (GBM). MSH2 deficiency was found in 6 cases, MSH6 deficiency in 9 cases, PMS2 and MLH1 deficiency in 2 cases. Median number of prior lines of chemotherapy was 1 (range 1-5). Stable disease (SD) was reported in 4 PTS (33%); 8 PTS showed progressive disease (PD). PTS with anaplastic gliomas showed a statistically significant association with SD (p = 0.03, OR = 3); all GBM PTS reported PD; status of MMRd (weak/absent), IDH (mutated/wild-type), MSH2 and MLH6 (deficient/proficient) were not associated with SD. Median follow up was 14.7 ms. OS was 5.6 ms (95% CI 0.1-13.8), PFS 2.4 ms (95% CI 1.8-2.9). OS was 2.8 ms and 5.6 ms (p = 0.9), PFS was 1.8 ms and 3.1 ms (p = 0.5) in PTS with wMMRd and aMMRd. PTS reporting SD and PD had PFS of 7.4 ms (95% CI 4.6-10.2) and 1.8 ms (95% CI 0.2-3.4), p = 0.002; OS was “not reached” and 2.8 ms in PTS having SD vs PD (p = 0.04). Grade ≥3 adverse events were reported in 8% of PTS.
Conclusions
A subgroup of recurrent MMRd HGG patients might benefit from Pem, especially those with anaplastic gliomas. There was a trend for a longer PFS and OS in PTS with aMMRd. Analyses for identifying additional molecular predictive factors is ongoing.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
5037 - CXCR4, CCR2 and CCR5 expression in subsets of tumor cells with stem and/or EMT features
Presenter: Olga Savelieva
Session: Poster Display session 1
Resources:
Abstract
5729 - Expression of mutant p53 affects cancer cell sensitivity to topotecan
Presenter: Rimma Mingaleeva
Session: Poster Display session 1
Resources:
Abstract
5725 - Breast cancer organoids a new tool for the prediction of drugs penetration and patient’outcome
Presenter: Giuseppina Roscigno
Session: Poster Display session 1
Resources:
Abstract
5680 - Aptamer-mediated exosomes detection for early breast cancer identification.
Presenter: Cristina Quintavalle
Session: Poster Display session 1
Resources:
Abstract
2460 - MicroRNA-181c promotes tamoxifen resistance in breast cancer cells via upregulation Akt/mTOR axis
Presenter: Alexander Scherbakov
Session: Poster Display session 1
Resources:
Abstract
3751 - Spatio-temporal separation of tumor infiltrating CD8+ T-cells and HER2/neu+ tumor cells in tumor-immune milieu of infiltrating ductal carcinoma of the breast
Presenter: Sandhya Sreedharan
Session: Poster Display session 1
Resources:
Abstract
4664 - Large genomic rearrangements in BRCA1 and BRCA2 genes in the Portuguese population.
Presenter: Joao Pinto
Session: Poster Display session 1
Resources:
Abstract
4611 - Non-BRCA1/2 hereditary breast and ovarian cancer: findings from a multidisciplinary program
Presenter: Ana Monteiro
Session: Poster Display session 1
Resources:
Abstract
5340 - Quantitative imaging and characterization of collagen patterns in high grade serous ovarian carcinoma (HGSOC)
Presenter: Ruby Huang
Session: Poster Display session 1
Resources:
Abstract
4209 - Semiquantitative assessment of vimentin expression in prostate cancer (PC)
Presenter: Marina Puchinskaya
Session: Poster Display session 1
Resources:
Abstract