The use of intravitreal chemotherapy has revolutionized the treatment of advanced intraocular retinoblastoma, as intravitreal melphalan has enabled difficult-to-treat vitreous tumor seeds to be controlled, leading to many more eyes being saved. However, melphalan hydrochloride (MH) degrades rapidly in solution, increasing logistical complexity with respect to time between medication preparation and administration for intravitreal administration under anesthesia for retinoblastoma. A new propylene glycol-free melphalan (PGFM) formulation has greater stability and could therefore improve access and adoption of intravitreal chemotherapy, allowing more children to retain their eye(s). We compared the efficacy and toxicity of both formulations, using our rabbit xenograft model and clinical patient experience. Three weekly 12.5 μg intravitreal injections of MH or PGFM (right eye), and saline (left eye), were administered to immunosuppressed rabbits harboring human WERI-Rb1 vitreous seed xenografts. Residual live cells were quantified directly, and viability determined by TUNEL staining. Vitreous seeds were reduced 91% by PGFM (p = 0.009), and 88% by MH (p = 0.004; PGFM vs. MH: p = 0.68). All residual cells were TUNEL-positive (non-viable). In separate experiments to assess toxicity, three weekly 12.5 μg injections of MH, PGFM, or saline were administered to non-tumor-bearing rabbits. Serial electroretinography, optical coherence tomography (OCT) and OCT-angiography were performed. PGFM and MH both caused equivalent reductions in electroretinography amplitudes, and loss of retinal microvasculature on OCT-angiography. The pattern of retinal degeneration observed on histopathology suggested that segmental retinal toxicity associated with all melphalan formulations was due to a vitreous concentration gradient-effect. Efficacy and toxicity were assessed for PGFM given immediately (within 1 h of reconstitution) vs. 4 h after reconstitution. Immediate- and delayed-administration of PGFM showed equivalent efficacy and toxicity. In addition, we evaluated efficacy and toxicity in patients (205 eyes) with retinoblastoma vitreous seeds, who were treated with a total of 833 intravitreal injections of either MH or PGFM as standard of care. Of these, we analyzed 118 MH and 131 PGFM monotherapy injections in whom serial ERG measurements were available to model retinal toxicity. Both MH and PGFM caused reductions in electroretinography amplitudes, but with no statistical difference between formulations. Comparing those patient eyes treated exclusively with PGFM versus those treated exclusively with MH, efficacy for tumor control and globe salvage was equivalent (PGFM vs. MH: 96.2% vs. 93.8%, p = 0.56), but PGFM-treated eyes received fewer injections than MH-treated eyes (average 3.2 ± 1.9 vs. 6.4 ± 2.1 injections, p < 0.0001). Taken together, these rabbit experiments and our clinical experience in retinoblastoma patients demonstrate that MH and PGFM have equivalent efficacy and toxicity. PGFM was more stable, with no decreased efficacy or increased toxicity even 4 h after reconstitution. We therefore now use PGFM over traditional MH for our patients for intravitreal treatment of retinoblastoma.

玻璃体内化疗的使用彻底改变了晚期眼内视网膜母细胞瘤的治疗，因为玻璃体内注射马法兰可以控制难以治疗的玻璃体肿瘤种子，从而挽救更多的眼睛。然而，盐酸美法仑（MH）在溶液中快速降解，增加了视网膜母细胞瘤麻醉下玻璃体内给药的药物准备和给药之间的时间复杂性。一种新的不含丙二醇的美法仑 (PGFM) 配方具有更高的稳定性，因此可以改善玻璃体内化疗的可及性和采用率，使更多的儿童能够保留他们的眼睛。我们使用我们的兔异种移植模型和临床患者经验比较了两种制剂的功效和毒性。对携带人 WERI-Rb1 玻璃体种子异种移植物的免疫抑制兔子进行每周三次 12.5 μg 玻璃体内注射 MH 或 PGFM（右眼）和盐水（左眼）。直接对残留的活细胞进行定量，并通过 TUNEL 染色测定活力。 PGFM 使玻璃体种子减少 91%（p = 0.009），MH 使玻璃体种子减少 88%（p = 0.004；PGFM 与 MH：p = 0.68）。所有残留细胞均为 TUNEL 阳性（无活力）。在评估毒性的单独实验中，对非荷瘤兔每周注射 3 次 12.5 μg MH、PGFM 或盐水。进行了串行视网膜电图检查、光学相干断层扫描（OCT）和OCT血管造影。 PGFM 和 MH 均导致视网膜电图振幅的同等降低，以及 OCT 血管造影上视网膜微脉管系统的损失。 组织病理学观察到的视网膜变性模式表明，与所有美法仑制剂相关的节段性视网膜毒性是由于玻璃体浓度梯度效应所致。评估立即（重构后 1 小时内）给予 PGFM 与重构后 4 小时给予的 PGFM 的功效和毒性。立即和延迟施用 PGFM 显示出相同的功效和毒性。此外，我们还评估了患有视网膜母细胞瘤玻璃体种子的患者（205 只眼睛）的疗效和毒性，这些患者总共接受了 833 次玻璃体内注射 MH 或 PGFM 作为标准治疗。其中，我们分析了 118 例 MH 和 131 例 PGFM 单药注射，其中连续 ERG 测量可用于模拟视网膜毒性。 MH 和 PGFM 均导致视网膜电图振幅降低，但制剂之间没有统计学差异。比较仅使用 PGFM 治疗的患者眼睛与仅使用 MH 治疗的患者眼睛，肿瘤控制和眼球挽救的功效相当（PGFM 与 MH：96.2% vs. 93.8%，p = 0.56），但 PGFM 治疗的眼睛接受的注射次数较少与 MH 治疗的眼睛相比（平均 3.2 ± 1.9 次与 6.4 ± 2.1 次注射，p < 0.0001）。总而言之，这些兔子实验和我们在视网膜母细胞瘤患者中的临床经验表明 MH 和 PGFM 具有同等的功效和毒性。 PGFM 更稳定，即使在重构后 4 小时，功效也没有下降或毒性增加。因此，我们现在使用 PGFM 而非传统 MH 为患者进行视网膜母细胞瘤的玻璃体内治疗。