Prognosis of glioblastoma patients improves significantly over time interrogating historical controls

BACKGROUND

Glioblastoma (GBM) is the most common devastating primary brain cancer in adults. In our clinical practice, median overall survival (mOS) of GBM patients seems increasing over time.

METHODS

To address this observation, we have retrospectively analyzed the prognosis of 722 newly diagnosed GBM patients, aged below 70, in good clinical conditions (i.e. Karnofsky Performance Status -KPS- above 70%) and treated in our department according to the standard of care (SOC) between 2005 and 2018. Patients were divided into two groups according to the year of diagnosis (group 1: from 2005 to 2012; group 2: from 2013 to 2018).

RESULTS

Characteristics of patients and tumors of both groups were very similar regarding confounding factors (age, KPS, MGMT promoter methylation status and treatments). Follow-up time was fixed at 24 months to ensure comparable survival times between both groups. Group 1 patients had a mOS of 19 months ([17.3-21.3]) while mOS of group 2 patients was not reached. The recent period of diagnosis was significantly associated with a longer mOS in univariate analysis (HR=0.64, 95% CI [0.51 - 0.81]), p < 0.001). Multivariate Cox analysis showed that the period of diagnosis remained significantly prognostic after adjustment on confounding factors (adjusted Hazard Ratio (aHR) 0.49, 95% CI [0.36-0.67], p < 0.001).

CONCLUSION

This increase of mOS over time in newly diagnosed GBM patients could be explained by better management of potentially associated non-neurological diseases, optimization of validated SOC, better management of treatments side effects, supportive care and participation in clinical trials.

P10.17.B Androgen receptor signalling has independent prognostic value and is associated with resistance to temozolomide and tumour growth in glioblastoma

Background

The spectrum of sex differences in glioblastoma (GBM) is a rising topic. GBM is more frequent (sex ratio M:F=1.6) and seem to have worse prognosis in males (M) compared to females. Androgen receptor (AR) is expressed in GBM but its role in GBM biology and clinics is not yet fully understood.

Material and Methods

We have selected from our tumour tissue bank: (i) GBM samples with clinical, pathological and molecular annotations and (ii) GBM-patient derived cell lines -GBM-PDCL- with transcriptomic profiling and available tissue from parental tumours.AR expression was investigated using multiplex IHC Opal stained-FFPE sections. Sensitivity of PDCL to hormonotherapy (dihydrotestosterone or enzalutamide EZT) alone or combined with temozolomide (TMZ) was tested using WST1 viability assay. Response to drugs were correlated to AR expression (high: log2 [FPKM] &gt;2 or low: log2 [FPKM] &lt;2). PDCLs dihydrotestosterone secretion was examined by ELISA in both supernatants and cell lysates.

Results

In our cohort of 1188 IDH muted GBM patients, the median follow-up was 27.7 (25.8-31.3). The sex ratio M:F was 1.68 and the median age at diagnosis was 57 years [18-69]. Compared to males, females have better prognosis with a median overall survival of 26.1 months vs 20.8 months (p&lt;0.0001). In multivariate analysis, male gender was an independent prognostic factor with a HR of 1.43 CI95%(1.21-1.69) (p&lt;0.0001) adjusted on age, MGMT status and Karnofsky indice . Although interaction between age and sex was not significant (p = 0.854), HR of gender varied through age category 1.53 CI95%( 1.01-2.33 ), 1.51 CI95%( 0.888-2.55 ) and 1.38 CI95%( 0.857-2.21) for males &lt;45 years, between 46-55 years and &gt; 55 years respectively. In GBM tumours, AR staining was positive in 5- 30% tumour cells. After 72h exposure to 10nM dihydrotestosterone, ARhigh GBM-PDCLs exhibit AR nuclear translocation and c-myc expression upregulation, suggesting functional activation of the receptor. AR pharmacological blockade increased temozolomide sensitivity in ARhigh GBM-PDCLs regardless of the patient’s sex. Moreover, ARhigh PDCLs secreted DHT, suggesting autocrine and paracrine AR stimulation in tumour microenvironment.

Conclusion

Our study highlights the independent prognostic significance of sex in GBM patients, where males exhibit a worse prognosis. In GBM-PDCL, we show that androgen receptor is (i) functional in vitro and (ii) associated with resistance to temozolomide. Further studies are needed to investigate the role of AR in tumour tissue microenvironment.

P11.66.A Immune checkpoint inhibitors related peripheral nerve disorders: clinical and electrophysiological particularities

Background

The immune-checkpoint inhibitors (ICIs) announced a new era in cancer treatment allowing long-term survival in advanced cancers. However, immune related adverse events impose treatment limitations being one of the main challenges when dealing with ICI treated patients. Neurologic toxicities have unique presentations and can progress rapidly, requiring prompt recognition. Among them, ICI-related peripheral nerve disorders are highly heterogeneous, profoundly debilitating, and insufficiently explored.

Material and Methods

We reviewed the clinical and electrodiagnostic features of a retrospective cohort of patients hospitalized in our centre for ICI related neuropathies. We applied the EFNS 2021 electrodiagnostic criteria for neuropathies and we researched the outcome according to the treatment received.

Results

We included 16 patients: 4 men and 12 women, median age 61 years (31-72) treated by anti-PD1 monotherapy (10) or antiCTLA4-antiPD1 combination (6). Median delay from ICIs initiation to neuropathy symptoms was 58,5 days (4 cycles), it seemed lower in combination group (median 33,5 days vs 81,5 days in monotherapy patients p=0,02). Half of patients presented with concurrent non-neurological irAE. CSF was inflammatory in 56% of cases, pleocytosis was seen in 57% of these. Cranial nerve involvement was rare (3/16) the most frequent phenotype was demyelinating polyneuropathy fulfilling EFNS 2021 EMG criteria in 10 cases. The other 6 presented with non-length dependent sensory neuropathy, (3) dysautonomic neuropathy (1) or sensory motor neuropathy with incomplete EFNS 2021 EMG criteria (2). ICI treatment was stopped, and steroids were the first line of treatment for all patients. However, 12/16 patients received additional iv immunoglobulin. Supplementary immunomodulation (cyclophosphamide, tocilizumab) was required in 2 cases. 75% of patients improved within a median of 4.5 months, median decrease in mRS was 2 points. Noteworthy, the rechallenge by antiPD1 monotherapy was proposed in 4 patients with a single neuropathy relapse.

Conclusion

Our series expand the knowledge on the clinical and electrophysiological phenotype of ICI related neuropathies improving their recognition in clinical practice. Moreover, our findings argue for the benefit of adding iv immunoglobulin to steroids as a first line treatment for different phenotypes of ICI related neuropathies.

P11.52.A Peripheral neuropathies after BRAF and/or MEK inhibitors treatment: a pharmacovigilance study

Background

BRAF (BRAFi) and MEK inhibitors (MEKi) demonstrated significant efficacy in the treatment of BRAF-activated tumours, firstly melanoma. Nevertheless, they are not devoid of adverse events. Sparse reports in the literature suggest the potential occurrence of peripheral neuropathies (PN) under BRAFi/MEKi treatment, but their characteristics remain poorly defined. We aimed to characterize the clinical phenotypes of PN occurring under BRAFi/MEKi treatment using a national pharmacovigilance database.

Material and Methods

We queried the French pharmacovigilance database for all cases of PN toxicity attributed to at least one BRAFi or MEKi compound. Only cases with a least symptoms description and nerve conduction studies (NCS) conclusion were included.

Results

Sixteen cases of PN occurred in 15 patients were identified. All patients had underlying melanoma. Two main phenotypes were seen. Six patients (dabrafenib-trametinib, n=3; vemurafenib, n=2; vemurafenib-cobimetinib, n=1) presented a length-dependent axonal polyneuropathy: symptoms were mostly sensory at lower limbs; NCS disclosed an axonal neuropathy; management and outcome were variable. Nine patients (dabrafenib-trametinib, n=5, encorafenib-binimetinib, n=3, and vemurafenib-cobimetinib, n=1) developed a demyelinating polyradiculoneuropathy: symptoms affected the four limbs and included hypoesthesia, weakness, and ataxia; cranial nerves were involved in four; NCS showed predominantly demyelinating features; most patients received intravenous immunoglobulins (n=6) or glucocorticoids (n=5), but the outcome was variable; one patient was rechallenged with a different BRAFi/MEKi with a rapid relapse.

Conclusion

Patients under treatment with BRAFi/MEKi may develop treatment-induced PN. Two main phenotypes are seen: a symmetric, axonal, length-dependent polyneuropathy, and a demyelinating polyradiculoneuropathy.

DRES-08. CLINICAL SIGNIFICANCE OF HYPERMUTATION IN GLIOMAS

BACKGROUND

Hypermutation is an emerging biomarker for predicting response to immunotherapy in cancer patients, however its clinical value in gliomas is not established. We sought to assess the determinants of hypermutation in gliomas, and its value for predicting response to standard of care and immune checkpoint blockade (ICB).

METHODS

We performed comprehensive genomic characterization of 2,420 clinically annotated gliomas. We assessed the clinical and molecular characteristics associated with hypermutation and relationships between hypermutation and response to cancer treatments.

RESULTS

Hypermutation occurred predominantly as an adaptive resistance mechanism to temozolomide in gliomas and was most prevalent in recurrent gliomas with MGMTpromoter methylation (33.8%), IDH1/2mutation (41.0%) or 1p/19q co-deletion (59.5%). Hypermutation was almost always associated with molecular defects in DNA mismatch repair (MMR), and was associated with shorter survival after its appearance based on multivariate analysis (hazard ratio 1.91; 95% CI 1.24–2.94; P=0.004). The molecular mechanisms whereby gliomas undergo hypermutation during therapy with alkylating agents were dissected using patient-derived glioma models in vitro and in vivo. Outcomes of hypermutated gliomas treated with immune checkpoint blockade or with standard of care agents will be presented at the conference.

CONCLUSIONS

Using the largest set of hypermutated gliomas described to date, this study establishes that mutational burden and mutation signatures are clinically and biologically significant biomarkers that can be used to predict therapy response and guide treatment decisions in gliomas

P10.06 Stiff limb syndrome associated to anti NMDA-R antibodies

BACKGROUND

Stiff person spectrum disorder is a group of rare conditions clinically characterized by the core symptoms of fluctuating muscular stiffness with superimposed spasms and an exaggerated startle response (hyperkplexia). It includes multiple variants amongst which are focal forms like stiff limb syndrome. Up to date, it was described in association with a spectrum of antibodies interfering with gabaergic transmission, most frequently antibodies targeting GAD, glycine receptor, amphiphysin and more rare dipeptidylpeptidase like protein 6, gephyrin, GABAAR and Glycine transporter 2.

MATERIAL AND METHODS

We report the case of a stiff limb syndrome associated to anti-NMDAR antibodies. The patient, a French 44-year male, with no antecedents presents with a 2-month history of painful spasms in his both legs resulting in a difficulty of walking and multiple falls. The diagnosis was supported by a stiff limb syndrome clinical pattern, a clinical response to treatment with benzodiazepines and baclofen and by the absence of other neurological finding that could have suggested an alternative diagnosis.

RESULTS

Anti NMDA-R antibodies were identified in blood and CSF samples using both immunofluorescence and cell-based assay. Any other intracellular and surface antibodies were negatives, GAD-ab included. Oncological evaluation was negative. The patient didn’t present encephalopathy signs and neuropsychological evaluation was normal. The patient received immunotherapy with one cure of intravenous immunoglobulins after an only partial improvement with symptomatic treatment.

CONCLUSION

This is the first case report of an association between the anti NMDA-R and stiff limb syndrome. Further investigations are needed to provide a better understanding of the pathophysiology of stiff person spectrum disorders.

OS9.7 Telomere length, TERTp mutation and ALT status in adult diffuse gliomas

BACKGROUND

The current classification of adult diffuse gliomas integrates two alternative telomere maintenance mechanisms: reactivation of telomerase activity by TERT promoter (TERTp) mutations or ATRX mutations associated with alternative length telomere (ALT). We investigated here the relation between these two mechanisms, telomere length, and outcome in a large series of diffuse gliomas.

MATERIAL AND METHODS

We performed C-circle assay (CCA) to determine ALT status, determined telomere length in tumor (RTLt) and leukocyte (RTLl) in a cohort of 354 adult diffuse gliomas, and sequenced ATRX gene. We calculated an age-adjusted telomere score considering tumor and leukocyte (blood) telomere length and corrected by age. This score was used in univariate and multivariate survival analyses to evaluate the potential impact of telomere length on the prognosis of gliomas. We used the TCGA LGG-GBM dataset to validate our findings in an independent cohort.

RESULTS

RTLl and RTLt were associated with ATRX mutation and ALT phenotype, and negatively associated with age and TERTp mutations. ATRX mutations (found in 52% (64/123) of samples) were mostly transitions (C>T or T>C), and were associated with ALT phenotype. None of 1p/19q co-deleted oligodendrogliomas harbored an ALT phenotype. No patients with TERTp mutations had ALT phenotype except for a very small subgroup of patients (3/87, 3.4%) suggesting that multiple ways of telomere maintenance, may co-exist in a single tumor, probably expressed in different clones. Telomere age-adjusted score was independently associated with better outcome (HR= 0.73 [95% CI 0.56–0.97], p-value 0.03 adjusted for age, TERTp mutation, IDH mutation, 1p/19q co-deletion and WHO grade). These results were validated using the LGG-GBM TCGA dataset.

CONCLUSION

We unravel the relation between RTLl and RTLt, TERTp mutation and ALT phenotype and describe a novel telomere age-adjusted score independently associated with better prognosis in adult diffuse gliomas.

P14.126 radiation-induced optic neuropathy

BACKGROUND

Optic neuropathy is an inflammation of the optic nerve leading to a rapidly progressive visual loss. Most frequent etiologies are multiple sclerosis, vasculitides, and infections. In the context of tumorous pathology, optic neuropathy can occur due to meningeal infiltration, tumoral compression, or antitumor therapeutics (radiation therapy, some targeted cancer therapies, and checkpoint inhibitors). In the current study, we examine radiation-induced optic neuropathy (RION), which is the most frequent among optic neuropathies caused by antitumor therapeutics.

MATERIAL AND METHODS

We present the cases of 3 patients who experienced RION. For each patient, we collected data on age, type of tumor, date and modalities of radiation-therapy, starting date of visual loss, ophthalmologic description, MRI images, treatment, and clinical and radiological evolution.

RESULTS

The three patients were aged 57 to 68 years old at the time of NORI. They had irradiation between 2013 and 2018. Two patients had proton therapy and one had whole brain irradiation. The visual loss occurred between seven and twelve months after the end of radiation therapy. In all patients the symptoms were bilateral and the loss of vision was rapidly worsened until culminating in almost total blindness. The MRI abnormalities were consistent with retrobulbar optic neuritis. The visual loss remained severe despite the treatment administered. High dose steroids had no clinical effect. Bevacizumab enabled a discrete subjective visual improvement in one patient, but a worsening of visual loss in another. Hyperbaric oxygen therapy had no clinical effect but was undertaken three months after the starting date of visual loss which is probably too late for efficiency. Interestingly one patient was treated with an anti-IL6 antibody (tocilizumab). It was administered in order to avoid fibrosis formation, which is the ultimate condition of the inflammatory process. The rationale is that radiation-induced opening of the bood-brain-barrier and destruction of endothelial and glial cells lead to reparation process through microglia activation. In-vitro studies showed an increased secretion of IL-6 (and other pro-inflammatory cytokines) by the activated microglia. Our patient could not experience benefit from tocilizumab, but the treatment was administered four months after the starting date of visual loss and fibrosis was probably already formed.

CONCLUSION

These cases are consistent with existing literature. The risk is mostly due to the total dose and dose per fraction of the irradiation and the prognosis is very poor with no efficient treatment at the present time. Anti-IL6 antibody could be an interesting treatment if administered at an early stage, but a future prospective clinical trial would be needed to clinically validate this hypothesis.