Secondary Prevention of Retinoblastoma Revisited

Deciphering metabolic heterogeneity in retinoblastoma unravels the role of monocarboxylate transporter 1 in tumor progression

BACKGROUND

Tumors exhibit metabolic heterogeneity, influencing cancer progression. However, understanding metabolic diversity in retinoblastoma (RB), the primary intraocular malignancy in children, remains limited.

METHODS

The metabolic landscape of RB was constructed based on single-cell transcriptomic sequencing from 11 RB and 5 retina samples. Various analyses were conducted, including assessing overall metabolic activity, metabolic heterogeneity, and the correlation between hypoxia and metabolic pathways. Additionally, the expression pattern of the monocarboxylate transporter (MCT) family in different cell clusters was examined. Validation assays of MCT1 expression and function in RB cell lines were performed. The therapeutic potential of targeting MCT1 was evaluated using an orthotopic xenograft model. A cohort of 47 RB patients was analyzed to evaluate the relationship between MCT1 expression and tumor invasion.

RESULTS

Distinct metabolic patterns in RB cells, notably increased glycolysis, were identified. This metabolic heterogeneity correlated closely with hypoxia. MCT1 emerged as the primary monocarboxylate transporter in RB cells. Disrupting MCT1 altered cell viability and energy metabolism. In vivo studies using the MCT1 inhibitor AZD3965 effectively suppressed RB tumor growth. Additionally, a correlation between MCT1 expression and optic nerve invasion in RB samples suggested prognostic implications.

CONCLUSIONS

This study enhances our understanding of RB metabolic characteristics at the single-cell level, highlighting the significance of MCT1 in RB pathogenesis. Targeting MCT1 holds promise as a therapeutic strategy for combating RB, with potential prognostic implications.

Ocular survival after intra-arterial chemotherapy for retinoblastoma improves with accrual of experience and programmatic evolution

BACKGROUND

Intra-arterial chemotherapy (IAC) for the treatment of intraocular retinoblastoma has gained recognition as a method to improve ocular salvage; however, there is a paucity of evidence supporting treatment factors prognosticating ocular survival.

METHODS

All patients with retinoblastoma treated with IAC at a single institution between December 2008 and December 2019 were evaluated. Patient demographics, tumor classification, prior treatments, procedural data, other non-IAC therapies, adverse reactions, procedural complications, ocular outcomes, and overall survival were assessed via retrospective chart review. Factors suggestive of increased ocular survival were identified via univariate and multivariate analyses. The impact of accrued treatment experience was evaluated by grouping eyes by the respective year, IAC treatment was initiated.

RESULTS

Forty-nine eyes of 43 patients were treated for retinoblastoma with IAC (256 total procedures). At least grade 3 neutropenia was observed following 19% of IAC procedures. The risk of neutropenia was not statistically different between single or multidrug IAC. Comparing those who received balloon-assisted intra-arterial chemotherapy (bIAC) in more than two-thirds of cycles to those who did not, the risk of arterial access site complications was not statistically different. Multivariate analysis revealed a significantly lower risk of enucleation associated with treatment era in years (hazard ratio [HR] = 0.52-1.00, p < .05) and laser therapies (HR = 0.02-0.60, p < .05).

CONCLUSIONS

Ocular survival rates in patients treated with IAC for retinoblastoma at our institution have increased over time. Accrued treatment experience and programmatic changes have likely contributed. Larger, prospective series may lead to a better understanding of factors that consistently contribute to better ocular salvage.

Recurrence and new tumor development after frontline intravenous chemotherapy for retinoblastoma: Risk factors and treatment results

PURPOSE

To evaluate the risk factors leading to recurrence and new tumor (NT) development in patients with retinoblastoma after intravenous chemotherapy (IVC) and to review the treatment outcomes.

MATERIALS AND METHODS

The records of 166 retinoblastoma cases (having 246 affected eyes) who underwent six-cycle IVC (vincristine, etoposide, and carboplatin) as primary treatment between October 1999 and August 2020 were reviewed retrospectively.

RESULTS

The mean ages at presentation were 9.0 (median: 8.0) and 9.2 (median: 8.5) months in cases with recurrence and NTs respectively. Recurrence was detected in 40 (16.3%) eyes, NTs in 29 (11.8%), and both recurrence/NTs in 24 (9.8%). The mean time elapsed till recurrence and NT was 10.7 months. Multivariable analysis showed that the factors predictive of recurrence were largest tumor base diameter (LTBD) >12 mm (p = 0.039) and presence of subretinal seeds at diagnosis (p = 0.043). Multivariable risk factors for the development of NTs were bilateral familial retinoblastoma (p = 0.001) and presence of subretinal seeds at diagnosis (p = 0.010). Mean follow-up was 80.1 (median: 72.5) months. By Kaplan-Meier analysis, the 1-, 3-, and 6-year recurrence and NT rates were 21.2%, 28.1%, and 28.7% and 14.9%, 22.6%, and 23.9% respectively. The most common treatment methods used for recurrent and/or NTs included cryotherapy, transpupillary thermotherapy, and intra-arterial chemotherapy. Enucleation was eventually required in 24/93 (25.8%) eyes. No patient developed metastasis.

DISCUSSION

Development of recurrence and/or NT after IVC was noted in 38% of all retinoblastoma eyes. Bilateral familial disease, LTBD >12 mm, and presence of subretinal seeds at baseline were risk factors for recurrence and NTs in this study.

Ocular Oncology-Primary and Metastatic Malignancies

Several neoplastic processes can involve the eye, either primarily or secondary to a systemic malignancy. The most common primary tumors of the eye include conjunctival and uveal melanoma, retinoblastoma, conjunctival and intraocular lymphoma, and ocular surface squamous neoplasia. Metastatic spread from systemic malignancies, especially of the breast and lung, also can involve the eye. A combination of ophthalmologic examination, ancillary testing, and cytologic/histopathologic evaluation leads to accurate diagnosis. Management consists of surgery, radiotherapy, chemotherapy, and immunotherapy delivered in various forms.

Neonatal Retinoblastoma

Retinoblastoma is the most common ocular malignancy of childhood. With an estimated 300 cases annually in the United States, retinoblastoma is nevertheless considered a rare tumor. Although retinoblastoma primarily affects younger children, diagnosis during the neonatal age range is less common. However, an understanding of patients at risk is critical for appropriate screening. Early detection and treatment by a multidisciplinary specialty team maximizes the chance for survival and ocular/vision salvage while minimizing treatment-related toxicity. Testing for alterations in the RB1 gene has become standard practice, and informs screening and genetic counseling recommendations for patients and their families.

Primary laser therapy as monotherapy for discrete retinoblastoma

BACKGROUND/AIM

Laser photocoagulation is less invasive than chemotherapy (systemic, intra-arterial or periocular) and brachytherapy. We studied the safety and efficacy of laser as primary monotherapy for discrete retinoblastoma with well-defined borders and attached retina.

METHODS

A single-institution retrospective non-comparative review (2004-2018) of discrete retinoblastoma tumours managed with primary laser (532 or 810 nm wavelength, 0.5-1 s duration and power titrated until desired tumour whitening). Efficacy was evaluated by tumour long-term stability avoiding non-laser therapies. Safety was evaluated by frequency of laser-related complications and uncontrollable tumour progression.

RESULTS

Eligible were 112 tumours in 55 eyes of 44 patients. Laser monotherapy (median 2 sessions) achieved initial remission in 95/112 (85%) tumour. Initial encircling only laser photocoagulation was associated with tumour progression (9/11, one tumour had vitreous seeding) compared with direct or combined photocoagulation techniques (0/94 and 0/7 tumours, respectively, p<0.001). Direct laser had no vitreous seeding, haemorrhage or injury to vital structures. Tumour recurrences developed in 52/112 (46%) tumour but repeat laser achieved long-term stability, except five tumour recurrences that required invasive therapy. Receiver operating characteristic analysis identified threshold largest basal diameter of 3 disc diameters (DD) for successful laser monotherapy, where 92/106 (87%) of tumours ≤3 DD and 0/6>3 DD achieved long-term stability with laser monotherapy (p<0.001). Overall, 35/55 (64%) eyes and 24/44 (55%) patients achieved long-term stability with laser monotherapy. No eye was enucleated for uncontrollable tumour progression.

CONCLUSIONS

Discrete retinoblastoma ≤3 DD can be effectively and safely managed with laser monotherapy, sparing a significant proportion of patients/eyes from more invasive therapies.