Differences in Childhood Growth Parameters Between Patients With Somatic and Heritable Retinoblastoma

Purpose

Little is known regarding differences in childhood growth between somatic and heritable retinoblastoma (Rb) populations. We aimed to compare childhood growth parameters between somatic and heritable Rb cohorts at birth and at time of diagnosis with Rb.

Methods

A multinational, longitudinal cohort study was conducted with patients from 11 centers in 10 countries who presented with treatment naïve Rb from January to December 2019. Variables of interest included age, sex, and size characteristics at birth and at time of presentation, as well as germline mutation status. After Bonferroni correction, results were statistically significant if the P value was less than 0.005.

Results

We enrolled 696 patients, with 253 analyzed after exclusion criteria applied. Between somatic (n = 39) and heritable (n = 214) Rb cohorts, with males and females analyzed separately, there was no significant difference in birth weight percentile, weight percentile at time of diagnosis, length percentile at time of diagnosis, weight-for-length percentile at time of diagnosis, or change of weight percentile from birth to time of diagnosis. Patients with heritable Rb had a smaller mean weight percentile at birth and smaller mean weight and length percentiles at time of diagnosis with Rb, although this difference was not statistically significant. All cohorts experienced a slight negative change of weight percentile from birth to time of diagnosis. No cohort mean percentiles met criteria for failure to thrive, defined as less than the 5th percentile.

Conclusions

Children with Rb seem to have normal birth and childhood growth patterns. There is no definitive evidence that somatic or heritable Rb has a biological or environmental impact on childhood growth parameters.

Incident glaucoma and ocular hypertension after periocular and intravitreal steroid injections: a claims-based analysis

BACKGROUND/AIMS

This study aims to determine the incidence and risk of open-angle glaucoma or ocular hypertension (OHT) following ocular steroid injections using healthcare claims data.

METHODS

We retrospectively reviewed deidentified insurance claims data from the IBM MarketScan Database to identify 19 156 adult patients with no prior history of glaucoma who received ocular steroid injections between 2011 and 2020. Patient demographics and steroid treatment characteristics were collected. Postinjection glaucoma/OHT development was defined as a new diagnosis of glaucoma/OHT, initiation of glaucoma drops, and/or surgical or laser glaucoma treatment. Cox proportional hazards models were used to determine the risk of glaucoma/OHT development within 5 years after first steroid injection.

RESULTS

Overall, 3932 (20.5%) patients were diagnosed with new glaucoma/OHT, 3345 (17.5%) started glaucoma drops and 435 (2.27%) required a laser or surgical glaucoma procedure within 5 years of first steroid injection. Triamcinolone subconjunctival injections were associated with a lower risk of glaucoma/OHT development than retrobulbar or intravitreal steroid injections (p<0.001, HR 0.68, 95% CI 0.59 to 0.79), whereas the 0.59 mg fluocinolone acetonide intravitreal implant had the highest risk of glaucoma/OHT development (p=0.001, HR 2.01, 95% CI 1.34 to 3.02). The risk of glaucoma/OHT development was also higher for patients receiving multiple steroid injections (p<0.001), with the largest increase in risk occurring after three total steroid injections.

CONCLUSION

Patients receiving ocular steroid injections are at risk of developing glaucoma/OHT, even with no prior glaucoma/OHT diagnosis or treatment. Patients should be closely monitored for the development of glaucoma following ocular steroid injections, particularly in the setting of intravitreal and/or repeated steroid administration.

Risk factors associated with abandonment of care in retinoblastoma: analysis of 692 patients from 10 countries

BACKGROUND

Rates of care abandonment for retinoblastoma (RB) demonstrate significant geographical variation; however, other variables that place a patient at risk of abandoning care remain unclear. This study aims to identify the risk factors for care abandonment across a multinational set of patients.

METHODS

A prospective, observational study of 692 patients from 11 RB centres in 10 countries was conducted from 1 January 2019 to 31 December 2019. Multivariate logistic regression was used to identify risk factors associated with higher rates of care abandonment.

RESULTS

Logistic regression showed a higher risk of abandoning care based on country (high-risk countries include Bangladesh (OR=18.1), Pakistan (OR=45.5) and Peru (OR=9.23), p<0.001), female sex (OR=2.39, p=0.013) and advanced clinical stage (OR=4.22, p<0.001). Enucleation as primary treatment was not associated with a higher risk of care abandonment (OR=0.59, p=0.206).

CONCLUSION

Country, advanced disease and female sex were all associated with higher rates of abandonment. In this analysis, enucleation as the primary treatment was not associated with abandonment. Further research investigating cultural barriers can enable the building of targeted retention strategies unique to each country.

The role of maternal age & birth order on the development of unilateral and bilateral retinoblastoma: a multicentre study

BACKGROUND/OBJECTIVES

Retinoblastoma is a common childhood intraocular malignancy, the bilateral form of which most commonly results from a de novo germline pathogenic variant in the RB1 gene. Both advanced maternal age and decreasing birth order are known to increase the risk of de novo germline pathogenic variants, while the influence of national wealth is understudied. This cohort study aimed to retrospectively observe whether these factors influence the ratio of bilateral retinoblastoma cases compared to unilateral retinoblastoma, thereby inferring an influence on the development of de novo germline pathogenic variants in RB1.

SUBJECTS/METHODS

Data from 688 patients from 11 centres in 10 countries were analysed using a series of statistical methods.

RESULTS

No associations were found between advanced maternal age, birth order or GDP per capita and the ratio of bilateral to unilateral retinoblastoma cases (p values = 0.534, 0.201, 0.067, respectively), indicating that these factors do not contribute to the development of a de novo pathogenic variant.

CONCLUSIONS

Despite a lack of a definitive control group and genetic testing, this study demonstrates that advanced maternal age, birth order or GDP per capita do not influence the risk of developing a bilateral retinoblastoma.

Acute iris vascular tuft hemorrhage treated successfully with intravitreal bevacizumab and pressure patching in a patient with branch retinal vein occlusion

Purpose

To report the presentation and management of active iris vascular tuft (IVT) hemorrhage and spontaneous hyphema in an eye with previous branch retinal vein occlusion (BRVO).

Observations

A 74-year-old male with a history of BRVO in the left eye presented with spontaneous hyphema and blurred vision. Clinical examination confirmed the presence of an actively bleeding IVT at the pupillary margin in the left eye. Sustained hemostasis was achieved following intravitreal bevacizumab injection and pressure patching of the eye.

Conclusions and Importance

This is the first case report to demonstrate pressure patching as a non-invasive, effective method of achieving hemostasis in the acute setting of IVT hemorrhage. Intravitreal vascular endothelial growth factor antagonists such as bevacizumab may also be useful in decreasing the risk of IVT hemorrhage in eyes with chronic ischemia, although further investigation is warranted.

The Effects of Breastfeeding on Retinoblastoma Development: Results from an International Multicenter Retinoblastoma Survey

The protective effects of breastfeeding on various childhood malignancies have been established but an association has not yet been determined for retinoblastoma (RB). We aimed to further investigate the role of breastfeeding in the severity of nonhereditary RB development, assessing relationship to (1) age at diagnosis, (2) ocular prognosis, measured by International Intraocular RB Classification (IIRC) or Intraocular Classification of RB (ICRB) group and success of eye salvage, and (3) extraocular involvement. Analyses were performed on a global dataset subgroup of 344 RB patients whose legal guardian(s) consented to answer a neonatal questionnaire. Patients with undetermined or mixed feeding history, family history of RB, or sporadic bilateral RB were excluded. There was no statistically significant difference between breastfed and formula-fed groups in (1) age at diagnosis (p = 0.20), (2) ocular prognosis measures of IIRC/ICRB group (p = 0.62) and success of eye salvage (p = 0.16), or (3) extraocular involvement shown by International Retinoblastoma Staging System (IRSS) at presentation (p = 0.74), lymph node involvement (p = 0.20), and distant metastases (p = 0.37). This study suggests that breastfeeding neither impacts the sporadic development nor is associated with a decrease in the severity of nonhereditary RB as measured by age at diagnosis, stage of disease, ocular prognosis, and extraocular spread. A further exploration into the impact of diet on children who develop RB is warranted.

Comprehensive Somatic Copy Number Analysis Using Aqueous Humor Liquid Biopsy for Retinoblastoma

Simple Summary

Aqueous humor (AH) liquid biopsy is an enriched source of cell-free circulating tumor-derived DNA for retinoblastoma (RB). The use of this AH liquid biopsy allows for genomic analysis of eyes in the absence of tumor tissue. Development of this platform was critical because direct tumor biopsy is prohibited in RB due to risk of extraocular tumor spread. In this retrospective study, we provide comprehensive, whole-genome analysis of the somatic copy number alterations (SCNAs) in 68 eyes of 64 RB patients. We show that the prevalence of specific SCNAs differ between eyes that required immediate enucleation (surgical removal) and eyes that were attempted to be saved but subsequently failed treatment, requiring secondary enucleation. Increases in chromosomal instability, or higher number of broad genomic alterations, predict higher risk clinical and biomarker features in these eyes. Prospective analyses are needed to further determine the clinical relevance and application of these findings.

Abstract

Aqueous humor (AH) liquid biopsy has been established as a surrogate tumor biopsy for retinoblastoma (RB). Previous AH studies have focused on highly recurrent RB somatic copy number alterations (SCNAs) including gain of 1q, 2p, 6p, and loss of 13q and 16q. In this retrospective study, we provide a comprehensive, whole-genome analysis of RB SCNAs and evaluate associated clinical features for 68 eyes of 64 RB patients from whom AH was obtained between December 2014 and October 2020. Shallow whole-genome sequencing of AH cell-free DNA was performed to assess for SCNAs. The prevalence of specific non-highly recurrent SCNAs, such as 20q gain and 8p loss, differed between primarily and secondarily enucleated eyes. Increases in chromosomal instability predict more advanced seeding morphology (p = 0.015); later age of diagnosis (p < 0.0001); greater odds of an endophytic tumor growth pattern (without retinal detachment; p = 0.047); tumor heights >10 mm (p = 0.09); and containing 6p gain, a biomarker of poor ocular prognosis (p = 0.004). The AH liquid biopsy platform is a high-yield method of whole-genome RB SCNA analysis, and SCNAs are associated with numerous clinical findings in RB eyes. Prospective analyses are encouraged to further elucidate the clinical relevance of specific SCNAs in RB.

Abstract 2247: Genomic heterogeneity in the aqueous humor cell-free DNA in a patient with bilateral retinoblastoma

Purpose: Germline alterations in the RB1 tumor suppressor gene predispose patients to developing retinoblastoma (RB) in both eyes. However, tumors in bilateral RB may not respond identically to treatment. The additional genomic events that occur independently in each eye during tumorigenesis are not well characterized. The aqueous humor (AH) provides a novel source of cell-free tumor-derived DNA (ctDNA) for liquid biopsy, enabling the in vivo study of RB tumors. In this case report, we use our AH liquid biopsy to compare genomic profiles between the right and left eyes of a single patient with heritable RB while also showing that ctDNA longitudinal dynamics correspond to therapeutic response.

Methods: One patient with bilateral RB was included. Multiple samples of AH were obtained from each eye during routine intravitreal melphalan therapy and following enucleation of the left eye. Routine clinical blood testing was performed to determine germline RB1 status. CtDNA was isolated from the AH and sequenced on an Illumina platform to assess genome-wide somatic copy number alterations (SCNAs). The same sequencing libraries were used to identify somatic RB1 pathogenic variants using a custom hybridization and next generation sequencing panel targeting RB1. Tumor fraction (TFx) was estimated using ichorCNA software.

Results: Five AH samples from both eyes (3 from the right eye and 2 from the left eye) were included. Peripheral blood RB1 testing detected germline 13q and 16p deletions. Targeted RB1 mutational analysis of AH ctDNA identified a different somatic RB1 mutation in each eye. At initial AH sampling, three SCNAs were present in the right eye and these same SCNAs persisted in further samples. Two SCNAs were initially detected in the left eye and were consistently identified in later sampling. Despite the same germline RB1 mutation, the second somatic mutation was different in each eye and there were distinct, non-overlapping patterns of SCNAs in each eye. In addition, the right eye demonstrated a progressive decrease in TFx corresponding with therapeutic responsiveness and ocular salvage. The left eye had persistently larger TFx values and required enucleation due to tumor recurrence.

Conclusions: Our AH liquid biopsy detected distinct genomic events between eyes in a patient with bilateral RB and TFx changes corresponding with disease activity. Identifying inter-eye genomic heterogeneity without the need for enucleated tumor tissue may help direct active management of RB, with particular usefulness in bilateral cases.

Citation Format: Elyssa Y. Wong, Liya Xu, Lishuang Shen, Mary E. Kim, Ashley Polski, Rishvanth K. Prabakar, Rachana Shah, Rima Jubran, Jonathan W. Kim, Jaclyn A. Biegel, Xiaowu Gai, Peter Kuhn, James Hicks, Jesse L. Berry. Genomic heterogeneity in the aqueous humor cell-free DNA in a patient with bilateral retinoblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2247.

Abstract 638: Enhancing the molecular diagnosis, prognosis, and treatment monitoring of retinoblastoma using cell free DNA in aqueous humor

Purpose: All previous studies of retinoblastoma (RB) aqueous humor (AH) analysis for tumor-derived cell-free DNA (cfDNA) have focused on sampling AH from eyes undergoing therapy; results from AH liquid biopsy at the time of diagnosis have not yet been published. Herein, we detail the diagnostic and prognostic genomic biomarkers found in the AH cfDNA from 7 RB eyes at diagnosis, each with longitudinal evaluation of over 12 months in follow-up.

Methods: Subjects included 7 eyes of 6 RB patients who underwent AH sampling at diagnosis. CfDNA from each AH sample was isolated and sequenced to assess genome-wide somatic copy number alterations (SCNAs), followed by targeted resequencing and mutation detection using a custom hybridization panel for RB1 and MYCN. Results were compared to peripheral blood RB1 testing and matched tumor samples, when available. Tumor fraction (TFx) was calculated using ichorCNA.

Results: Five of 7 diagnostic AH samples contained highly recurrent RB SCNAs, 4 with large scale alterations and 1 with a focal RB1 gene deletion. Mutational analysis of AH cfDNA identified pathogenic somatic variants in 5 diagnostic AH samples with high variant allele frequency, while the remaining 2 diagnostic AH samples had either a high TFx from SCNAs or a focal MYCN amplification. Taken together, somatic tumoral genomic information was detected in all 7 diagnostic AH samples. The 2 eyes that required enucleation had poor prognostic biomarkers (chromosome 6p gain and MYCN amplification) present at the time of diagnosis. TFx from longitudinal AH sampling corresponded to treatment response over time in all cases for which sequential AH samples were available.

Conclusions: This study demonstrates that AH sampling at diagnosis is both feasible and safe. Molecular profiling of AH provides a plethora of diagnostic and prognostic information from only a single 0.1 mL AH sample.

1

Citation Format: Liya Xu, Mary E. Kim, Ashley Polski, Rishvanth K. Prabakar, Chen-Ching Peng, Patricia Chévez-Barrios, Jonathan W. Kim, Rachana Shah, Rima Jubran, Peter Kuhn, David Cobrinik, James Hicks, Jesse L. Berry. Enhancing the molecular diagnosis, prognosis, and treatment monitoring of retinoblastoma using cell free DNA in aqueous humor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 638.

Response criteria for intraocular retinoblastoma: RB-RECIST

Standardized guidelines for assessing tumor response to therapy are essential for designing and conducting clinical trials. The Response Evaluation Criteria In Solid Tumors (RECIST) provide radiological standards for assessment of solid tumors. However, no such guidelines exist for the evaluation of intraocular cancer, and ocular oncology clinical trials have largely relied on indirect measures of therapeutic response-such as progression-free survival-to evaluate the efficacy of treatment agents. Herein, we propose specific criteria for evaluating treatment response of retinoblastoma, the most common pediatric intraocular cancer, and emphasize a multimodal imaging approach for comprehensive assessment of retinoblastoma tumors in clinical trials.

Establishing the Clinical Utility of ctDNA Analysis for Diagnosis, Prognosis, and Treatment Monitoring of Retinoblastoma: The Aqueous Humor Liquid Biopsy

Simple Summary

Due to prohibition of direct tumor biopsy for patients with retinoblastoma, the prospect of a liquid biopsy for the identification of tumor derived biomarkers for this cancer is enticing. The aqueous humor (AH) is a rich source of eye-specific tumoral genomic information. This is the first prospective study wherein we demonstrate that molecular profiling of the AH at diagnosis and longitudinally throughout therapy has clinical utility for diagnosis, prognosis, and monitoring of treatment response. Tumoral genomic information was detected in 100% of diagnostic aqueous humor samples, including single nucleotide variants in the RB1 tumor suppressor gene and large-scale somatic chromosomal alterations. All eyes that failed therapy and required enucleation had poor prognostic biomarkers for ocular salvage present in the aqueous humor at time of diagnosis. This highlights the potential of the AH liquid biopsy for direct clinical applications to precision oncology to direct genome-specific, personalized treatment for retinoblastoma patients.

Abstract

Because direct tumor biopsy is prohibited for retinoblastoma (RB), eye-specific molecular biomarkers are not used in clinical practice for RB. Recently, we demonstrated that the aqueous humor (AH) is a rich liquid biopsy source of cell-free tumor DNA. Herein, we detail clinically-relevant molecular biomarkers from the first year of prospective validation data. Seven eyes from 6 RB patients who had AH sampled at diagnosis and throughout therapy with ≥12 months of follow-up were included. Cell-free DNA (cfDNA) from each sample was isolated and sequenced to assess genome-wide somatic copy number alterations (SCNAs), followed by targeted resequencing for pathogenic variants using a RB1 and MYCN custom hybridization panel. Tumoral genomic information was detected in 100% of diagnostic AH samples. Of the seven diagnostic AH samples, 5/7 were positive for RB SCNAs. Mutational analysis identified RB1 variants in 5/7 AH samples, including the 2 samples in which no SCNAs were detected. Two eyes failed therapy and required enucleation; both had poor prognostic biomarkers (chromosome 6p gain or MYCN amplification) present in the AH at the time of diagnosis. In the context of previously established pre-analytical, analytical, and clinical validity, this provides evidence for larger, prospective studies to further establish the clinical utility of the AH liquid biopsy and its applications to precision oncology for RB.

Cell-Free DNA Tumor Fraction in the Aqueous Humor Is Associated With Therapeutic Response in Retinoblastoma Patients

Purpose

The aqueous humor (AH) liquid biopsy enables in vivo evaluation of tumor-derived cell-free DNA (cfDNA) from retinoblastoma (RB) eyes. Herein, we test our hypothesis that longitudinal dynamics of AH cfDNA—including tumor fraction (TFx) and somatic copy number alteration (SCNA) amplitude—correspond to therapeutic response.

Methods

Eyes with ≥3 AH extractions during intravitreal chemotherapy (IVM) or at secondary enucleation between 2015 to 2019 were included. AH cfDNA was sequenced to assess RB SCNA amplitude; ichorCNA software was used to estimate TFx. Eyes without SCNAs or with TFx < 0.10 across all samples were excluded. Therapeutic responses for each eye were determined from clinical records. Statistical analyses included Mann-Whitney U and Pearson correlation tests.

Results

Twenty eyes of 20 patients underwent ≥3 AH extractions; 6 eyes lacked SCNAs or had TFx < 0.10 throughout sampling and were excluded. Clinical progression was associated with significantly higher SCNA amplitudes and TFx values than regression (P ≤ 0.04). Relative increases in TFx (ΔTFx 1.86 ± 2.22) were associated with disease progression, whereas relative decreases in TFx (ΔTFx 0.53 ± 0.36) were associated with disease regression (P < 0.00001). A ≥15% increase in TFx relative to baseline during treatment was associated with an over 90-fold increased likelihood of clinical progression (odds ratio = 90.67, 95% confidence interval = 8.30–990.16, P = 0.0002). TFx and SCNA amplitude were significantly positively correlated throughout sampling (P ≤ 0.002).

Conclusions

Longitudinal changes in AH-derived cfDNA TFx and SCNA amplitude are concordant with clinical responses of intraocular RB during active therapy.

Translational Relevance

Longitudinal evaluation of AH cfDNA may provide an objective, quantitative way to monitor therapeutic response and disease burden in RB patients.

Simultaneous identification of clinically relevant RB1 mutations and copy number alterations in aqueous humor of retinoblastoma eyes

BACKGROUND

Detection of germline RB1 mutations is critical for risk assessment of retinoblastoma (RB) patients. Assessment of somatic copy number alterations (SCNAs) is also critically important because of their prognostic significance. Herein we present a refined approach for the simultaneous identification of RB1 variants and SCNAs in the aqueous humor (AH) of RB eyes.

MATERIALS AND METHODS

Subjects included 7 eyes of 6 RB patients that underwent AH extraction, and 4 matched tumor samples. Cell-free DNA (cfDNA) was isolated and sequenced to assess genome-wide SCNAs. The same sequencing libraries then underwent targeted resequencing and mutation detection using a custom hybridization panel that targets RB1 and MYCN. Illumina paired-end 2x150bp sequencing was used to characterize single-nucleotide variants (SNVs) and loss of heterozygosity (LOH). Results were compared to peripheral blood RB1 testing. Tumor fraction (TFx) was calculated using ichorCNA.

RESULTS

Four of 7 AH samples contained clinically significant SCNAs. Of the 3 other samples, 1 showed focal MYCN amplification and 1 showed focal RB1 deletion. All 4 enucleated tumors contained SCNAs. Mutational analysis of tumor DNA identified all first hits (2 germline RB1 SNVs, 2 germline CNAs) and second hits (4 RB1 SNVs). RB1 variants in AH were concordant with those obtained from corresponding tumor tissue and blood. In AH samples without paired tumor, both RB1 hits were identified with high variant allele frequency, even in the absence of SCNAs.

CONCLUSIONS

AH liquid biopsy is a minimally invasive, in vivo alternative to tissue analysis for the simultaneous identification of RB1 variants and SCNAs in RB eyes.

Abstract 186: Gain of chromosome 6p is a molecular biomarker for prognostication of retinoblastoma ocular survival: The aqueous humor surrogate tumor biopsy

Purpose: Aqueous humor (AH) is a novel source of tumor-derived cell-free DNA (cfDNA) and can serve as a surrogate tumor biopsy, or liquid biopsy, for retinoblastoma (RB). We previously identified a somatic copy number alteration (SCNA) gain of chromosome 6p as associated with a 10-fold increased risk of enucleation. In this study, we provide a 2-year extended update to further explore 6p gain as a prognostic biomarker for ocular survival.

Methods: Patients diagnosed with RB from 12/2014 - 7/2019 from whom AH was sampled were included. AH was extracted via clear corneal paracentesis at diagnosis, during intravitreal injection of chemotherapy or enucleation. CfDNA was extracted; shallow whole genome sequencing was performed to assess for cfDNA tumor fractions and highly recurrent RB SCNAs (gain of 1q, 2p, 6p, loss of 13q, 16q). Patient demographics, treatment regimen and globe salvage were recorded.

Results: 50 eyes from 46 patients were included: 27 eyes were salvaged and 23 were enucleated. Most eyes (36/50,72%) were TNM stage cT2b. 116 samples of AH were analyzed. There were no cases of orbital relapse or metastatic spread. The median follow-up was 30 months (range 6-64 mos). After genomic evaluation, 33 / 50 eyes (66%) demonstrated one or more highly-recurrent RB SCNAs and 39/50 (78%) demonstrated any measurable SCNA. Gain of 6p was the most prevalent RB SCNA among all 50 eyes (50%), followed by 1q gain (38%), 16q loss (30%), 2p gain (including 3 focal MYCN gains; 18%), and 13q loss (16%). RB SCNAs were significantly more prevalent in enucleated eyes (21/23, 91.3%) than in salvaged eyes (12/27, 44.4%; Fisher's exact, P=0.0007). Of these, 6p gain was particularly more prevalent in enucleated eyes (17/23, 73.9%) than in salvaged eyes (8/27, 29.6%; Chi-squared, P=0.002) Of all the RB SCNAs, the presence of 6p gain in the cfDNA in the AH portended nearly 10 times greater odds of being enucleated (OR=9.87,95% CI=1.75-55.65, P=0.009). No single other SCNA had a statistically significant power to predict enucleation although there was a trend towards significance for 2p/focal MYCN gain (P=0.09) limited by the few number of eyes with this SCNA.

Conclusions: Although we previously identified chromosomal gain of 6p as a potential indicator of an aggressive phenotype in RB, that study included a smaller cohort of patients and limited follow-up. With extended follow-up and nearly double the number of eyes and AH samples, the data continue to demonstrate that AH is a high-yield surrogate tumor biopsy, and the presence of RB-specific SCNAs–specifically gain of 6p–has the potential to serve as a prognostic biomarker for RB.

Citation Format: Jesse L. Berry, Liya Xu, Ashley Polski, Rishvanth Prabakar, Mark Reid, Jonathan Kim, Peeter Kuhn, James Hicks. Gain of chromosome 6p is a molecular biomarker for prognostication of retinoblastoma ocular survival: The aqueous humor surrogate tumor biopsy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 186.

Abstract 185: Longitudinal aqueous humor sampling reflects treatment response in retinoblastoma patients

Purpose: The aqueous humor (AH) liquid biopsy for retinoblastoma (RB) facilitates in vivo sampling of tumor-derived cell-free DNA (cfDNA). We previously demonstrated that tumor-derived somatic copy number alterations (SCNAs) in AH predict poor ocular salvage. However, whether AH sampling can be used to monitor clinical response throughout therapy remains unknown. In this retrospective study, we hypothesize that SCNA amplitude (amp) and tumor fraction (TFx) of RB cfDNA in the AH correspond to treatment response over time.

Methods: Eyes that required intravitreal chemotherapy (IVM) for tumor seeding and had ≥3 sequential AH samples extracted during active IVM therapy and/or at secondary enucleation between 2015-2019 were included. Shallow whole-genome sequencing of AH cfDNA was performed to assess RB SCNA amp, and ichorCNA software estimated cfDNA TFx based on SCNAs present. Eyes without SCNAs in any sample were removed from final analysis. For each eye, clinical treatment response (regression vs progression) at each sample timepoint relative to the initial sample timepoint was determined from clinical records. Mann-Whitney U test was used for statistical analyses.

Results: Twenty eyes of 20 patients had ≥3 AH extractions during the study period; 6 eyes had no SCNAs and were excluded from final analysis. Disease progression at any timepoint was associated with significantly higher SCNA amp (1.65±0.34) and TFx (0.57±0.36) than disease regression (SCNA amp 1.22±0.34, P=0.0002; TFx 0.29±0.34, P=0.01). Relative increases in SCNA amp (Δamp 1.19±0.35) and TFx (ΔTFx 3.68±5.27) from start to end of longitudinal AH sampling were associated with overall disease progression, whereas relative decreases in SCNA amp (Δamp 0.78±0.08; P=0.005) and TFx (ΔTFx 0.55±0.52; P=0.006) were associated with overall disease regression.

Conclusions: We demonstrate that increases and decreases in AH-derived SCNA amp and TFx during therapy tend to correspond to clinical progression and regression of disease, respectively. Our findings suggest that longitudinal AH evaluation throughout active RB therapy may provide a novel quantitative method of monitoring RB treatment response.

Citation Format: Ashley Polski, Liya Xu, Rishvanth K. Prabakar, Jonathan W. Kim, Peter Kuhn, David Cobrinik, James Hicks, Jesse L. Berry. Longitudinal aqueous humor sampling reflects treatment response in retinoblastoma patients [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 185.

Abstract 452: Simultaneous identification of clinically relevant RB1 Mutations and somatic copy number alterations in the Aqueous Humor of retinoblastoma eyes

Purpose: Retinoblastoma (RB) tumorigenesis is associated with mutations in the RB1 tumour suppressor gene and somatic copy number alterations (SCNAs). Both alleles of the RB1 gene must be mutated for tumour development. The initial RB1 mutation may be germline or somatic. However, the somatic RB1 mutation was only detectable in enucleated RB eyes, when the tumour samples were available. The aqueous humor (AH) can serve as a surrogate to direct tumour biopsy and can be done in vivo. In this study, we demonstrate that both whole genome SCNAs and RB1 mutations can be simultaneously assayed in the AH liquid biopsy.

Methods: AH from 7 eyes of 6 RB patients and 4 matched tumor samples were included. AH was extracted via clear corneal paracentesis. Cell-free DNA (cfDNA) was isolated and constructed into whole genome libraries. Low pass whole genome sequencing was performed for copy number alteration analysis. The same libraries were further used for capture-based targeted NGS for mutation detection. Custom hybridization capture panel manufactured from Agilent includes the whole gene region of RB1 gene, MCYN gene, and all exons of BCOR and CREBBP genes (Agilent SureSelect Tier1). Captured libraries were sequenced on Illumina platform with paired-end 150 cycles mode. Bioinformatics analysis was performed for single-nucleotide variant (SNV) and loss of heterozygosity (LOH) detection using an in-house pipeline (information available on request). Comparison was also made to clinically available peripheral blood RB1 mutation screening (CHLA, CPM).

Results: Somatic whole genome SCNAs were detected in all 4 enucleated tumours. Among 7 evaluated AH samples, 5 contained SCNAs and the remaining 2 were flat without alterations under current analysis setting. Mutational analysis of tumour DNA from 4 enucleated eyes identified 6 RB1 SNVs. Mutation results from AH cfDNA were concordant with results obtained from corresponding tumour tissue and peripheral blood screening, when available. In the 3 AH samples without paired tumours, both RB1 hits were identified with high variant allele frequency (VAF), indicating high tumour fraction in AH of RB eyes.

Conclusions: Use of a customized hybridization capture approach facilitated identification of RB1 mutation(s), together with low pass whole genome analysis for SCNA profiling in the same AH liquid biopsy provides the opportunity to identify the genomic and genetic alterations simultaneously for one diseased eye. This refined approach provides the potential to further investigate the spectrum of RB1 mutations and SCNA subtypes in both enucleated and salvaged RB eyes. It is crucial to distinguish between these alternative mechanisms, for the wider implications for management of patient and family members.

Citation Format: Liya Xu, Lishuang Shen, Ashley Polski, Rishvanth K. Prabakar, Mark Reid, Peter Kuhn, David E. Cobrinik, James Hicks, Xiaowu Gai, Jesse Berry. Simultaneous identification of clinically relevant RB1 Mutations and somatic copy number alterations in the Aqueous Humor of retinoblastoma eyes [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 452.

Chromosome 6p Amplification in Aqueous Humor Cell-Free DNA Is a Prognostic Biomarker for Retinoblastoma Ocular Survival

Aqueous humor contains tumor-derived cell-free DNA (cfDNA) and can serve as a liquid biopsy for retinoblastoma. We previously associated somatic copy-number alteration (SCNA) 6p gain with a 10-fold increased risk of enucleation. Here we provide a 2-year update to further explore 6p gain as a prognostic biomarker for ocular survival. Patients diagnosed with retinoblastoma from December 2014 to July 2019 from whom aqueous humor was sampled were included. cfDNA was extracted and shallow whole-genome sequencing performed to identify highly recurrent retinoblastoma SCNAs (gain of 1q, 2p, 6p, loss of 13q, 16q). 116 aqueous humor samples from 50 eyes of 46 patients were included: 27 eyes were salvaged, 23 were enucleated. Highly recurrent retinoblastoma SCNAs were found in 66% eyes. 6p gain was the most prevalent SCNA (50% eyes). It was particularly more prevalent in enucleated eyes (73.9%) than in salvaged eyes (29.6%; P = 0.004). 6p gain in aqueous humor cfDNA portended nearly 10-fold increased odds of enucleation (OR = 9.87; 95% confidence interval = 1.75-55.65; P = 0.009). In the enucleated eyes, 6p gain was associated with aggressive histopathologic features, including necrosis, higher degrees of anaplasia, and focal invasion of ocular structures. With extended follow-up and nearly double the aqueous humor samples, we continue to demonstrate 6p gain as a potential prognostic biomarker for retinoblastoma. IMPLICATIONS: Aqueous humor is a high-yield source of tumor-derived DNA in retinoblastoma eyes. Detection of 6p gain in the aqueous humor allows for targeted, patient-centered therapies based on this molecular prognostic marker. Prospective, multicenter studies with aqueous humor sampled from all eyes at diagnosis are warranted to validate these findings.

Abstract A70: Aqueous humor is superior to blood as a liquid biopsy for retinoblastoma

Purpose: To evaluate whether blood demonstrates similar potential as aqueous humor (AH) to be used as a liquid biopsy for retinoblastoma (RB) and whether tumor-derived cell-free DNA (cfDNA) can be isolated as effectively from the blood as AH.

Methods: AH was extracted via clear corneal limbal paracentesis from RB eyes at diagnosis or during intravitreal injection of chemotherapy. Matched peripheral venous blood samples were drawn. Shallow whole-genome sequencing was performed to assess for cell-free tumor DNA fractions and highly recurrent somatic copy number alterations (SCNAs) in the blood and AH samples.

Results: Seven samples of AH taken at diagnosis and 13 samples at the time of intravitreal injection were compared to matched blood samples. The presence of any detectable SCNA in the AH was 11/20 and 0/20 in the blood (p=&lt;0.001). The median size distribution of cfDNA molecules in the AH was 157.5 bp versus 181.5 bp in the blood (p=&lt;0.001).

Conclusions: The AH appears to be superior to the blood as a source of cell-free tumor DNA for retinoblastoma, thus a better target for development as a liquid biopsy for this cancer.

Citation Format: Liya Xu, Jesse L Berry, Ashley Polski, Rima Jubran, Peter Kuhn, Jonathan W. Kim, James Hicks. Aqueous humor is superior to blood as a liquid biopsy for retinoblastoma [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr A70.

Variability in retinoblastoma genome stability is driven by age and not heritability

Retinoblastoma (RB) is a childhood intraocular cancer initiated by biallelic inactivation of the RB tumor suppressor gene (RB1^-/- ). RB can be hereditary (germline RB1 pathogenic allele is present) or non-hereditary. Somatic copy number alterations (SCNAs) contribute to subsequent tumorigenesis. Previous studies of only enucleated RB eyes have reported associations between heritability status and the prevalence of SCNAs. Herein, we use an aqueous humor (AH) liquid biopsy to investigate RB genomic profiles in the context of germline RB1 status, age, and International Intraocular Retinoblastoma Classification (IIRC) clinical grouping for both enucleated and salvaged eyes. Between 2014 and 2019, AH was sampled from a total of 54 eyes of 50 patients. Germline RB1 status was determined from clinical blood testing, and cell-free DNA from AH was analyzed for SCNAs. Of the 50 patients, 23 (46.0%; 27 eyes) had hereditary RB, and 27 (54.0%, 27 eyes) had non-hereditary RB. Median age at diagnosis was comparable between hereditary (13 ± 10 months) and non-hereditary (13 ± 8 months) eyes (P = 0.818). There was no significant difference in the prevalence or number of SCNAs based on (1) hereditary status (P > 0.56) or (2) IIRC grouping (P > 0.47). There was, however, a significant correlation between patient age at diagnosis, and (1) number of total SCNAs (r[52] = 0.672, P < 0.00001) and (2) number of highly-recurrent RB SCNAs (r[52] = 0.616, P < 0.00001). This evidence does not support the theory that specific molecular or genomic subtypes exist between hereditary and non-hereditary RB; rather, the prevalence of genomic alterations in RB eyes is strongly related to patient age at diagnosis.

Next-Generation Technologies and Strategies for the Management of Retinoblastoma

Retinoblastoma (RB) is an inherited retinal disorder (IRD) caused by the mutation in the RB1 gene or, rarely, by alterations in the MYCN gene. In recent years, new treatment advances have increased ocular and visual preservation in the developed world. The management of RB has improved significantly in recent decades, from the use of external beam radiation to recently, more localized treatments. Determining the underlying genetic cause of RB is critical for timely management decisions. The advent of next-generation sequencing technologies have assisted in understanding the molecular pathology of RB. Liquid biopsy of the aqueous humor has also had significant potential implications for tumor management. Currently, patients’ genotypic information, along with RB phenotypic presentation, are considered carefully when making treatment decisions aimed at globe preservation. Advances in molecular testing that improve our understanding of the molecular pathology of RB, together with multiple directed treatment options, are critical for developing precision medicine strategies to treat this disease.

The RB1 Story: Characterization and Cloning of the First Tumor Suppressor Gene

The RB1 gene is the first described human tumor suppressor gene and plays an integral role in the development of retinoblastoma, a pediatric malignancy of the eye. Since its discovery, the stepwise characterization and cloning of RB1 have laid the foundation for numerous advances in the understanding of tumor suppressor genes, retinoblastoma tumorigenesis, and inheritance. Knowledge of RB1 led to a paradigm shift in the field of cancer genetics, including widespread acceptance of the concept of tumor suppressor genes, and has provided crucial diagnostic and prognostic information through genetic testing for patients affected by retinoblastoma. This article reviews the long history of RB1 gene research, characterization, and cloning, and also discusses recent advances in retinoblastoma genetics that have grown out of this foundational work.

Extending far and wide: the role of biopsy and staging in the management of ocular surface squamous neoplasia

IMPORTANCE

Although the most recent American Joint Committee on cancer staging guidelines for ocular surface squamous neoplasia place a heightened emphasis on biopsy and histopathologic analysis, the interpretation and clinical relevance of these staging criteria are not always clear. We address limitations of using histopathologic analysis to predict clinical outcomes and suggest less-invasive assessments.

BACKGROUND

To investigate the impact of histopathologic depth of invasion on outcomes for tumours with the common presentation of multiple structure involvement.

DESIGN

Retrospective chart review at tertiary institution.

SAMPLES

Of 41 eyes with ocular surface squamous neoplasia between 2012 and 2017, 27 tumours involving multiple ocular structures clinically were included.

METHODS

Biopsied tumours were determined to be invasive beyond the basement membrane or non-invasive; non-biopsied tumours were clinically identified with unknown depth of invasion. Outcomes were compared using Fisher's exact or Student's t tests.

MAIN OUTCOME MEASURES

Proportion of tumours cured, recurred and/or persisting.

RESULTS

Twelve tumours (44%) received primary excisional biopsy, 10 (37%) received chemotherapy without biopsy and 5 (19%) received chemotherapy and biopsy. Clinical diagnosis was correct in all biopsied cases. While there were no significant differences in outcomes between invasive vs non-invasive tumours or treatments, there was a trend toward larger basal diameter in recurrent tumours regardless of treatment.

CONCLUSIONS AND RELEVANCE

When ocular surface squamous neoplasia tumours with similar clinical involvement were compared, histopathologic depth of invasion was not predictive of clinical outcomes. Future staging criteria may consider the potential of largest basal dimension for more accurate prognostication.