Highlighting A Handful of Posters from the 2026 ASPHO Conference

Poster 01 - Agreement Between Upfront Biopsy and Delayed Nephrectomy Histology: A Report from COG Study AREN03B2

Data from the Children’s Oncology Group (COG) AREN03B2 study (NCT00898365), presented at the 2026 ASPHO Conference, highlighted an overall histologic agreement rate of 84.8% (kappa coefficient = 0.54) between upfront renal biopsy (RB) and delayed nephrectomy (DN) specimens.¹ Notably, 12.4% of patients initially diagnosed with favorable histology Wilms tumor (FHWT) were found to have anaplastic histology at the time of DN.

Among the 508 patients with FHWT on initial biopsy, 9.1% were diagnosed with diffuse anaplasia and 3.3% with focal anaplasia at nephrectomy.

Upfront RB was accurate for non-FHWT diagnoses, with 51 of 52 patients showing concordant DN pathology. Patient age also served as a critical indicator; FHWT was found in only 40% of patients under 6 months and 51% of those over 10 years old.

The retrospective report utilized data from the COG AREN03B2 protocol, which opened in 2006 for patients under 30 years of age with renal tumors on imaging.

• Cohort Size: Of 6572 total enrollees, 5720patients had non-syndromic unilateral renal tumors.
• Procedures: While the majority (4754) underwent initial nephrectomy, 855patients had an upfront RB.

Poster 12 - Efficacy of ALK Inhibitors in Combination with Eflornithine (DFMO) in High-Risk Neuroblastoma (HRNB)

Results from the NMTRC006B expanded access trial (NCT03581240), presented at the 2026 ASPHO Conference, indicate that combining the polyamine synthesis inhibitor eflornithine (Iwilfin) with ALK inhibitors provides significant clinical benefit for patients with high-risk neuroblastoma (HRNB) harboring ALK aberrations.² Patients treated at the completion of standard upfront therapy achieved a 2-year event-free survival (EFS) of 88.9% and a 2-year overall survival (OS) of 100%.

In the relapsed subgroup (n=15), the combination yielded a 2-year EFS of 31.1% and a 2-year OS of 61.6%. Two refractory patients demonstrated 100% survival for both EFS and OS at the 2-year mark.

The average treatment duration was 498 days, and the most common grade 3 or higher adverse effects (AEs) were anemia and infections. Low-grade transient fever and elevated liver enzymes were also observed. Notably, no patients discontinued the study due to treatment-related toxicity.

The analysis evaluated 26 patients with HRNB harboring ALK mutations, amplifications, or overexpression. Patients received oral eflornithine at either a standard dose of 750 ± 250 mg/m² BID (n = 19) or a central nervous system-penetrating dose of 2500 mg/m² BID (n = 7). The ALK inhibitors utilized included lorlatinib (Lorbrena; n=23), crizotinib (Xalkori; n=2), and ceritinib (Zykadia; n=1).

At enrollment, 9 patients were post-standard upfront therapy, 15 had relapsed disease, and 2 were refractory. Eight patients entered the study with evaluable disease, while 18 were non-evaluable.

Poster 15 - Eltrombopag (EPAG) Safety in Pediatric Solid Tumors Receiving Intensive Chemotherapy

Eltrombopag(Promacta) was deemed safe for the treatment of pediatric patients with solid tumors who were receiving intensive chemotherapy in a single-center, open-label, prospective pilot trial shared at the 2026 ASPHO Conference.³

Of 9 patients who were enrolled in the trial, 7 received eltrombopag. No serious drug-related AEs were observed in any patients on the trial. The 2 patients who did not receive eltrombopagwere ineligible due to platelet counts above threshold on the planned start day. It was noted that 1 patient developed thrombocytosis.

Eligible patients for the study were between 1 and 18 years of age, and all were enrolled between 2021 and 2025.

Eltrombopagwas administered orally once daily after completion of each chemotherapy cycle and continued until 2 days prior to the next chemotherapy cycle or a rise in platelet counts. Study follow-up occurred until 30 days after the last study dose.

The primary end point of the trial was to assess the safety of eltromobag in pediatric patients receiving intensive chemotherapy for malignant solid tumors; secondary end points were to determine the efficacy of eltrombopagin pediatric patients undergoing intensive chemotherapy for malignant solid tumors.

The investigators noted that there were several limitations in the study, including the small number of patients, the lack of a control arm, and the study not being powered for efficacy.

Poster 344 - NXT007 prophylaxis in people with hemophilia A with/without inhibitors: a global Phase I/II study

A data reporting from the first 3 cohorts of a phase 1/2 global multiple-ascending-dose study (NCT05987449) of NXT007, a next-generation bispecific antibody, in patients with hemophilia A revealed that the agent was well tolerated.⁴

Across all cohorts, which included a total of 22 patients, 96 AEs were observed across 86.4% of patients. Of note, 9.1% had serious AEs, 13.6% had grade 3 or higher AEs, 27.3% had treatment-related AEs, and 22.7% had local injection-site reactions. One patient had elevated alanine aminotransferase or aspartate aminotransferase with elevated bilirubin or clinical jaundice.

One serious AE each was observed in cohort 2 and cohort 3.

Reporting showed that 86.3% of patients tested positive for anti-drug antibodies during the study, though they had no effect on NXT007 pharmacokinetics, efficacy, or safety. The mean thrombin generation peak heights at day 29 were comparable in cohorts 2 and 3 with the pre-study dose.

Treated bleeds were not required in 86.4% of patients, and, after the initiation of NXT007 treatment, annualized bleeding rates decreased. One specific patient in cohort 3 had 4 spontaneous joint bleeds in the maintenance period which were considered secondary to direct trauma to an aberrant arterial vessel between the artificial knee joint surfaces of a prosthetic knee joint.

Eligible patients in the trial had severe or moderate hemophilia A and were aged from 12 to 59 years. Overall, there were 2 patients in the trial below the age of 18 years.

Patients were split into 3 cohorts:

• Cohort 1: NXT007 was administered subcutaneously at 0.42 mg/kg once every 2 weeks for 2 cycles, then at 0.28 mg/kg once every 4 weeks.
• Cohort 2: NXT007 was administered subcutaneously at 1.05 mg/kg every 2 weeks for 2 cycles, then at 0.70 mg/kg every 3 weeks.
• Cohort 3: NXT007 was administered subcutaneously at 1.62 mg/kg every 2 weeks for 2 cycles, then 1.06 mg/kg every 4 weeks.

Poster 627 - Role of Social Determinants of Health on Survival in Youth with Acute Lymphoblastic Leukemia in a Southern California Cohort

Neighborhood-level social determinants of health (SDOH) impacted survival outcomes for adolescents with acute lymphoblastic leukemia (ALL), with those from higher-vulnerability neighborhoods experiencing worse outcomes.⁵ Specifically, the 5-year EFS was 57% for those in high Neighborhood Vulnerability Index (NVI) areas, compared with 90% for those in low NVI areas (P = .036).

The entire cohort maintained a 5-year overall survival (OS) of 92% (95% CI, 87%-95%) and an EFS of 86% (95% CI, 79%-90%), but when stratified by age, disparities were evident. In patients from 1 to 10 years, the 5-year EFS was 93% (95% CI, 83%-97%) for patients with an NVI of 0 to 0.64, compared with a 5-year EFS of 79% (95% CI, 52%-88%) in those with an NVI of 0.65 to 0.99. In those aged 11 to 14 years, those values were 94% (95% CI, 63%-99%) vs 100%, respectively; in those aged 15 to 18 years, they were 90% (95% CI, 47%-99%) vs 57% (95% CI, 17%-84%).

• Clinical Complications: Patients 15 to 18 years of age had higher rates of bacteremia (43% vs 17% in those younger than 9 years; P = .015) and intensive care unit (ICU) admissions (54% vs 31%; P = .020).
• Socioeconomic Correlations: High NVI (0.65–0.99) was strongly associated with Hispanic ethnicity (72% vs 44% in low NVI; P <.001), public insurance (89% vs 35%; P <.001), and preferred use of Spanish for medical communication (43% vs 13%; P <.001).

This retrospective study analyzed a cohort of 211 children and youth treated for ALL at Rady Children's Health between 2015 and 2023. The patient population included:

• Age Groups: 1–4 years (35%), 5–9 years (30%), 10–14 years (21%), and 15–18 years (13%).
• Demographics: 59% male and 55% Hispanic.
• Disease Characteristics: 87% B-cell lineage and 13% T-cell lineage.

The aim of the study was to evaluate OS and EFS, as well as clinical outcomes and their associations with parental SDoH, in a cohort of children with ALL.

Reference

1. Ortiz MV, Benedetti DJ, Renfro LA, et al. Agreement between upfront biopsy and delayed nephrectomy histology: a report from COG study AREN03B2. Presented at the 2026 ASPHO Annual Meeting; April 29-May 2, 2026; Minneapolis, MN. Poster 12.
2. Sholler GS, Lincoln J, Bergendahl G, et al. Efficacy of ALK inhibitors in combination with eflornithine (DFMO) in high-risk neuroblastoma (HRNB). Presented at the 2026 ASPHO Conference; April 29-May 2, 2026; Minneapolis, MN. Poster 14.
3. Aguirre AL, Gho D, Malogolowkin M, et al. Eltrombopag (EPAG) safety in pediatric solid tumors receiving intensive chemotherapy. Presented at the 2026 ASPHO Conference; April 29-May 2, 2026; Minneapolis, MN. Poster 15.
4. Mancuso ME, Matino D, Hart D, et al. NXT007 prophylaxis in people with hemophilia A with/without inhibitors: a global phase I/II study. Presented at the 2026 ASPHO Conference; April 29-May 2, 2026; Minneapolis, MN. Poster 344.
5. Durocher M, Lee D, Rios A, et al. Role of social determinants of health on survival in youth with acute lymphoblastic leukemia in a Southern California cohort. Presented at the 2026 ASPHO Conference; April 29-May 2, 2026; Minneapolis, MN. Poster 627.