Genetic susceptibility to cognitive decline following craniospinal irradiation for pediatric central nervous system tumors

BACKGROUND

Survivors of pediatric central nervous system (CNS) tumors treated with craniospinal irradiation (CSI) exhibit long-term cognitive difficulties. Goals of this study were to evaluate longitudinal effects of candidate and novel genetic variants on cognitive decline following CSI.

METHODS

Intelligence quotient (IQ), working memory (WM), and processing speed (PS) were longitudinally collected from patients treated with CSI (n = 241). Genotype-by-time interactions were evaluated using mixed-effects linear regression to identify common variants (minor allele frequency > 1%) associated with cognitive performance change. Novel variants associated with cognitive decline (P < 5 × 10-5) in individuals of European ancestry (n = 163) were considered replicated if they demonstrated consistent genotype-by-time interactions (P < .05) in individuals of non-European ancestries (n = 78) and achieved genome-wide statistical significance (P < 5 × 10-8) in a meta-analysis across ancestry groups.

RESULTS

Participants were mostly males (65%) diagnosed with embryonal tumors (98%) at a median age of 8.3 years. Overall, 1150 neurocognitive evaluations were obtained (median = 5, range: 2-10 per participant). One of the five loci previously associated with cognitive outcomes in pediatric CNS tumors survivors demonstrated significant time-dependent IQ declines (PPARA rs6008197, P = .004). Two variants associated with IQ in the general population were associated with declines in IQ after Bonferroni correction (rs9348721, P = 1.7 × 10-5; rs31771, P = 7.8 × 10-4). In genome-wide analyses, we identified novel loci associated with accelerated declines in IQ (rs116595313, meta-P = 9.4 × 10-9), WM (rs17774009, meta-P = 4.2 × 10-9), and PS (rs77467524, meta-P = 1.5 × 10-8; rs17630683, meta-P = 2.0 × 10-8; rs73249323, meta-P = 3.1 × 10-8).

CONCLUSIONS

Inherited genetic variants involved in baseline cognitive functioning and novel susceptibility loci jointly influence the degree of treatment-associated cognitive decline in pediatric CNS tumor survivors.

LGG-22. SJ901: Phase I/II evaluation of single agent mirdametinib (PD-0325901), a brain-penetrant MEK1/2 inhibitor, for the treatment of children, adolescents, and young adults with low-grade glioma (LGG)

BACKGROUND: MEK inhibitor trials in pediatric low-grade glioma (pLGG) have yielded promising results, but there remains room for improvement since objective responses are rarely complete and disease recurrence after completion of therapy is common. Mirdametinib (PD-0325901) is a highly selective MEK1/MEK2 inhibitor that, in preclinical studies, has been reported to have superior blood-brain-barrier penetration compared to other MEK inhibitors. As such, we recently launched the SJ901 clinical trial (NCT04923126) to determine the safety, recommended phase 2 dose, pharmacokinetics, and preliminary efficacy of mirdametinib in patients with pLGG when administered continuously. Here, we present preliminary phase 1 data. METHODS: SJ901 is a multi-arm phase I/II trial of mirdametinib in patients &gt;2 and &lt;25 years with LGG. Phase I requires participants to have no prior exposure to MEK inhibitors and recurrent/progressive disease with biopsy-proven evidence of MAPK pathway activation. Three escalating dose levels (2 mg/m2/dose BID, 2.5mg/m2/dose BID and 3mg/m2/dose BID) are planned using a rolling 6 design. RESULTS: Accrual began in June 2021. As of Jan 13, 2022, eleven patients enrolled: 5 on dose level 1 (DL1) and 6 on dose level 2 (DL2). Median age is 10 (3-21) years. Ten patients have somatic gene rearrangements (7 BRAF, 1 MYB, 1 RAF1, 1 FGFR1) and one has an NF1 germline mutation. Four have metastatic disease. No dose-limiting toxicities occurred for DL1 (whereas data are pending for DL2) and only grade 1/2 treatment-related adverse events have been observed. No MEK-related retinopathy or cardiopathy has been observed. Four of the six patients with at least one follow-up disease evaluation have a minor response (&gt;25%-&lt;50% decrease). Median time on therapy is 6.6 (2.2-7) months. No disease progressions have occurred. CONCLUSION: Thus far, mirdametinib is well-tolerated and clinically promising when dosed continuously in patients with recurrent/progressive pLGG. More information will be forthcoming.

INSP-07. Improving cognitive outcomes for children treated for cancer: moving beyond the cure

With improved survival rates, increasing numbers of childhood cancer survivors are living with long-term cognitive deficits that negatively impact their ability to attain important life milestones. Our collaborative research program has focused on characterizing cognitive outcomes associated with specific treatment modalities to inform modifications in front-line therapy. This line of investigation has demonstrated the negative cognitive impact of high radiation dose/large treatment volume, posterior fossa syndrome, treatment-related ototoxicity, and lower socioeconomic status (SES). Research-informed, treatment approaches under investigation include proton radiotherapy and hippocampal sparing irradiation, molecularly based risk-adapted therapy, surgical approaches with reduced risk of injury, and on-therapy otoprotectants, as well as identification of modifiable factors that are driving the protective effects of higher SES. Our research also strives to improve specification of cognitive deficits following treatment, at the behavioral and neural systems level, to identify targets for intervention. Study findings have revealed disease- and treatment- related alterations in neural systems supporting attention, working memory, and executive functions, as well as genetic factors that increase risk for cognitive late effects. We are now using sophisticated connectivity brain mapping with enhanced sensitivity to behaviorally-relevant changes in brain organization and sensitivity to intervention-based neuroplasticity to guide cognitive intervention development. A primary research focus moving forward is development of empirically validated interventions that prevent or mitigate cognitive late effects among childhood cancer survivors. Our studies have demonstrated the efficacy of stimulant medications, computerized cognitive training, and aerobic exercise for children treated for cancer, as well as the limitations to these approaches. Current investigations include use of neuroprotectant agents during radiotherapy, combining multiple interventions, interventions tailored to children undergoing treatment in infancy, and the use of virtual reality to increase intervention engagement. Our ultimate benchmark of success is ensuring children are not only cured of cancer but also experience a high quality of life.

Outcome and molecular analysis of young children with choroid plexus carcinoma treated with non-myeloablative therapy: results from the SJYC07 trial

Background

Choroid plexus carcinoma (CPC) is a rare and aggressive tumor of infancy without a clear treatment strategy. This study describes the outcomes of children with CPC treated on the multi-institutional phase 2 SJYC07 trial and reports on the significance of clinical and molecular characteristics.

Methods

Eligible children <3 years-old with CPC were postoperatively stratified to intermediate-risk (IR) stratum if disease was localized or high-risk (HR) stratum, if metastatic. All received high-dose methotrexate-containing induction chemotherapy. IR-stratum patients received focal irradiation as consolidation whereas HR-stratum patients received additional chemotherapy. Consolidation was followed by oral antiangiogenic maintenance regimen. Survival rates and potential prognostic factors were analyzed.

Results

Thirteen patients (median age: 1.41 years, range: 0.21-2.93) were enrolled; 5 IR, 8 HR. Gross-total resection or near-total resection was achieved in ten patients and subtotal resection in 3. Seven patients had TP53-mutant tumors, including 4 who were germline carriers. Five patients experienced progression and died of disease; 8 (including 5 HR) are alive without progression. The 5-year progression-free survival (PFS) and overall survival rates were 61.5 ± 13.5% and 68.4 ± 13.1%. Patients with TP53-wild-type tumors had a 5-year PFS of 100% as compared to 28.6 ± 17.1% for TP53-mutant tumors (P = .012). Extent of resection, metastatic status, and use of radiation therapy were not significantly associated with survival.

Conclusions

Non-myeloablative high-dose methotrexate-containing therapy with maximal surgical resection resulted in long-term PFS in more than half of patients with CPC. TP53-mutational status was the only significant prognostic variable and should form the basis of risk-stratification in future trials.

QOL-01. LONGITUDINAL COMPARISON OF NEUROCOGNITIVE TRAJECTORIES IN PEDIATRIC MEDULLOBLASTOMA PATIENTS TREATED WITH PROTON VERSUS PHOTON RADIOTHERAPY

PURPOSE

By reducing dose to normal brain tissue, proton radiotherapy (PRT) may lessen neurocognitive risk traditionally associated with photon radiotherapy (XRT). We examined change in neurocognitive scores over time in pediatric medulloblastoma patients treated with PRT versus XRT.

METHODS

Neurocognitive scores from 79 patients (37 PRT, 42 XRT) were examined. Patients were treated between 2007–2018 on the same treatment protocols that differed only by craniospinal modality (PRT versus XRT). Change in scores over time since diagnosis were compared between groups.

RESULTS

Groups were similar on most demographic/clinical variables: sex (67.1% male), age at diagnosis (mean 8.6 years), CSI dose (median 23.4 Gy), length of follow-up (mean 4.3 years), and parental education (mean 14.3 years). Boost dose (p<0.001) and margin (p=0.001) differed between groups. Adjusting for covariates, the PRT group exhibited superior outcomes in global IQ, perceptual reasoning, and working memory versus the XRT group (all p<0.05). The XRT group exhibited significant decline in global IQ, working memory, and processing speed (all p<0.05). The PRT group exhibited stable scores in all domains except processing speed (p=0.003). Posterior fossa syndrome imparted risk independent of modality.

CONCLUSION

This is the first study comparing neurocognitive trajectories between pediatric patients treated for medulloblastoma with PRT versus XRT on comparable, contemporary protocols. PRT was associated with more favorable neurocognitive outcomes in most domains compared to XRT, although processing speed emerged as vulnerable in both groups. This is the strongest evidence to date of an intellectual sparing advantage with PRT in the treatment of pediatric medulloblastoma.

NCMP-25. CLINICAL FEATURES, NEUROLOGIC RECOVERY, AND RISK PREDICTION OF POST-OPERATIVE POSTERIOR FOSSA SYNDROME: A PROSPECTIVE STUDY

INTRODUCTION

Posterior fossa syndrome (PFS) is a known consequence of medulloblastoma resection. Our aim was to clinically define PFS, its evolution over time, and ascertain risk factors for its development and poor recovery.

METHODS

Children with medulloblastoma treated at St Jude Children’s Research Hospital from 6/2013-7/2019 received standardized neurological examinations, before and periodically after radiation therapy. Most (98.3%) were enrolled on the ongoing multi-institutional protocol (SJMB12; NCT 01878617).

RESULTS

Sixty (34%) of 178 evaluated children had PFS. Forty (23%) had complete mutism (PFS1) and 20 (11%) had diminished speech (PFS2). All children with PFS had severe ataxia and 42.5% of PFS1 had movement disorders. By multivariable analysis, younger age (p=0.0005) and surgery in a low-volume surgery center (p=0.0146) increased PFS risk, while SHH tumors had reduced risk (p=0.0025). Speech and gait returned in PFS1/PFS2 children at a median of 2.3/0.7 and 2.1/1.5 months respectively, however, 12 (44.4%) of 27 PFS1 children with 12 months of follow-up were non-ambulatory at one-year. Movement disorder (p= 0.037) and high ataxia score (p&lt; 0.0001) were associated with delayed speech recovery. Older age (p= 0.0147) and high ataxia score (p&lt; 0.0001) were association with delayed gait return. Symptoms improved in all children but no child with PFS had normal neurologic examination at a median of 23 months after surgery.

CONCLUSION

Categorizing PFS in to types 1 and 2 has prognostic relevance. Almost half of the children with PFS1 remained non-ambulatory at 12-month follow-up. Surgical experience was a major modifiable contributor to the development of PFS.

SAT-457 Hypothalamic-Pituitary Disorders after Conformal Radiation Therapy for Childhood and Young Adult Low-Grade Glioma or Ependymoma

Purpose To describe the prevalence, risk factors, latency time and adverse health outcomes of hypothalamic-pituitary (HP) disorders among children and young adults who received focal conformal radiation therapy (RT) for brain tumors. Methods Cohort study of 355 patients, aged ≤ 25 years at diagnosis, treated with high-dose (54-59.4 Gy) RT using photons between 1996 and 2016 for low-grade glioma or ependymoma. Patients (median age, 6.4 years at RT exposure) received systematic endocrine follow-up for a median of 10.1 years (range 0.1-19.6). Associations between HP disorders and risk factors, as well as adverse health outcomes were determined using multivariable regression analysis. Results The prevalence was 37.2% (95% CI 32.1%-42.4%) for growth hormone (GH) deficiency (GHD), 17.7% (95% CI 13.2%-23.0%) for luteinizing hormone/follicle-stimulating hormone deficiency (LH/FSHD), 14.9% (95% CI 11.2%-19.2%) for thyroid-stimulating hormone deficiency (TSHD), 10.3% (95% CI 7.3%-14.1%) for adrenocorticotropic hormone deficiency (ACTHD), and 12.6% (95% CI 8.8%-17.2%) for central precocious puberty (CPP). Tumor involvement in the HP region and shorter follow-up time were significantly associated with GHD, LH/FSHD, TSHD and ACTHD. CPP primarily occurred in patients with HP tumor involvement. GHD, treated in 84 (63.6%) patients, was associated with a higher odds of short stature (OR 2.77; 95% CI 1.34-5.70) and low bone mineral density (BMD) (OR 3.47; 95% CI 1.16-10.40), while TSHD demonstrated an independent association with dyslipidemia (OR 5.54; 95% CI 1.66-18.52). TSHD (P = 0.02), ACTHD (P = 0.0002), LH/FSHD (P = 0.01) and CPP (P = 0.002) were associated with lower intelligence quotient scores; GHD (P = 0.02), ACTHD (P = 0.01), LH/FSHD (P = 0.01) and CPP (P = 0.04) with worse attention scores; GHD (P = 0.0003), ACTHD (P = 0.02) and LH/FSHD (P = 0.02) with lower memory scores. GH treatment was associated with a higher risk for secondary tumors (OR 2.22; 95% CI 1.05-4.67), but did not increase the risk for tumor recurrence or mortality. Conclusion HP disorders occur frequently during follow-up in patients exposed to high-dose RT and may have a significant impact on physical and neurocognitive well-being. Whether further optimization of endocrine management could allow better outcomes, requires additional investigation.

Effect of cerebellum radiation dosimetry on cognitive outcomes in children with infratentorial ependymoma

PURPOSE

Cognitive decline is a recognized effect of radiation therapy (RT) in children treated for brain tumors. The importance of the cerebellum and its contribution to cognition have been recognized; however, the effect of RT on cerebellum-linked neurocognitive deficits has yet to be explored.

METHODS AND MATERIALS

Seventy-six children (39 males) at a median 3.3 years of age (range, 1-17 years old) were irradiated for infratentorial ependymoma from 1997 to 2008. The total prescribed dose was 54 to 59.4 Gy administered to the postoperative tumor bed with 5- or 10-mm clinical target volume margin. Age-appropriate cognitive and academic testing was performed prior to the start of RT and was then repeated at 6 months and annually throughout 5 years. The anterior and posterior cerebellum and other normal brain volumes were contoured on postcontrast, T1-weighted postoperative magnetic resonance images registered to treatment planning computed tomography images. Mean doses were calculated and used with time after RT and other clinical covariates to model their effect on neurocognitive test scores.

RESULTS

Considering only the statistically significant rates in longitudinal changes for test scores and models that included mean dose, there was a correlation between mean infratentorial dose and intelligence quotient (IQ; -0.190 patients/Gy/year; P=.001), math (-0.164 patients/Gy/year; P=.010), reading (-0.137 patients/Gy/year; P=.011), and spelling scores (-0.147 patients/Gy/year; P=.012), where Gy was measured as the difference between the mean dose received by an individual patient and the mean dose received by the patient group. There was a correlation between mean anterior cerebellum dose and IQ scores (-0.116 patients/Gy/year; P=.042) and mean posterior cerebellum dose and IQ (-0.150 patients/Gy/year; P=.002), math (-0.120 patients/Gy/year; P=.023), reading (-0.111 patients/Gy/year; P=.012), and spelling (-0.117 patients/Gy/year; P=.015) scores.

CONCLUSIONS

Sparing portions of the cerebellum should be considered in RT planning for children with infratentorial ependymoma because of the potential impact of radiation dose on cognitive function.

Characterization, treatment, and outcome of intracranial neoplasms in the first 120 days of life

Little is known about brain tumors in early infancy. Investigators reviewed the records of 27 patients (12 boys and 15 girls) diagnosed within 120 days of birth. The median age was 66 days (range, 0-110 days) at diagnosis. All patients underwent surgery; 18 received adjuvant chemotherapy, and 3 received adjuvant chemotherapy and radiation therapy. The median follow-up was 2.1 years (range, 0.2-21.6 years). At last encounter, 15 patients were alive, and 11 had no evidence of disease. Ten patients died of progressive disease, and 2 died of treatment-related complications. All survivors experienced late effects, including endocrine, neurologic, and cognitive deficits. Of the 13 patients who completed neurocognitive assessments, 7 had an IQ score less than 70. Children in whom brain tumors arise during early infancy can be cured with conventional therapy; however, contemporary approaches can adversely affect long-term function, and families need to be aware of these effects when making therapeutic decisions.