Therapeutic strategies and clinical evolution of patients with infantile fibrosarcoma: a unique paediatric case series

BACKGROUND

Infantile fibrosarcoma is the most frequent soft tissue sarcoma in newborns or children under one year of age. This tumour often implies high local aggressiveness and surgical morbidity. The large majority of these patients carry the ETV6-NTRK3 oncogenic fusion. Hence, the TRK inhibitor larotrectinib emerged as an efficacious and safe alternative to chemotherapy for NTRK fusion-positive and metastatic or unresectable tumours. However, real-world evidence is still required for updating soft-tissue sarcoma practice guidelines.

OBJECTIVE

To report our experience with the use of larotrectinib in pediatric patients.

METHODS

Our case series shows the clinical evolution of 8 patients with infantile fibrosarcoma under different treatments. All patients enrolled in this study received informed consent for any treatment.

RESULTS

Three patients received larotrectinib in first line. No surgery was needed with larotrectinib, which led to the rapid and safe remission of tumours, even in unusual anatomical locations. No significant adverse effects were observed with larotrectinib.

CONCLUSION

Our case series supports that larotrectinib may be a therapeutic option for newborn and infant patients with infantile fibrosarcoma, especially in uncommon locations.

Treatment of infantile fibrosarcoma associated to an abdominal aortic aneurysm with larotrectinib: a case report

Infantile fibrosarcoma (IFS) is a rare pediatric tumor which often presents the ETV6-NTRK3 gene fusion. NTRK3 encodes the neurotrophin-3 growth factor receptor tyrosine kinase, a druggable therapeutic target. Selective tropomyosin receptor kinase (TRK) inhibitors, such as larotrectinib, have shown efficacy and safety in the treatment of IFS. We report a case of an abdominal IFS diagnosed in a newborn associated with an aortic aneurysm that was successfully treated with larotrectinib without relevant adverse effects.

Comparison of two chemotherapy regimens in Ewing sarcoma (ES): Overall and subgroup results of the Euro Ewing 2012 randomized trial (EE2012)

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Background: In 2010, different chemotherapy regimens were standard in Europe and the USA for newly diagnosed ES. In the absence of novel agents to investigate, comparison of these two strategies was considered worthwhile. Methods: Newly diagnosed localised or metastatic ES patients aged 5-50 were eligible. Patients were randomized to receive either the European regimen (Arm A) of VIDE (vincristine [V], ifosfamide [I], doxorubicin [D] and etoposide [E]) induction and VAI or VAC (V, actinomycin D and I or cyclophosphamide [C]) consolidation or the USA regimen (Arm B) of compressed VDC/IE induction and IE/VC consolidation. The primary outcome measure was event-free survival (EFS); secondary outcomes included overall survival (OS) and toxicity. The design was Bayesian with interpretation based on posterior probabilities (with non-informative priors) – i.e. probability that true hazard ratio (HR) < 1.0 given the data [Pr(HR<1.0|data)], with 95% credible intervals (CrI) reported. HRs were obtained from Cox models adjusted for baseline stratification parameters. Heterogeneity tests (HT) were used to investigate whether the treatment effect differed according to baseline parameters. Analysis was intention-to-treat. Results: Between December 2013 and May 2019, 640 patients were randomised (320 to each arm) from 10 European countries. Baseline stratification factors were: sex (58% male; 42% female); age (41% <14 years; 59% 14+ years); disease type (74% localised, 17% lung/pleural metastasis, 9% other metastasis); tumour volume (56% <200 ml, 44% >200 ml); country (37% UK, 31% France, 32% other). Median follow-up was 1.7 years. The HRs (95% CrI) were 0.70 (0.51, 0.95) for EFS and 0.64 (0.42, 0.96) for OS in favour of Arm B, with posterior probabilities of 98% for both that Arm B was better. Subgroup analyses showed no evidence that this benefit differed depending the baseline features, with no HT being close to significance (table). There were no major differences in acute toxicity: 68% of patients in Arm A experienced serious adverse events and 67% in Arm B. Conclusions: VDC/IE chemotherapy is superior to VIDE for both EFS and OS, with no excess toxicity. This benefit is consistent across all baseline stratification parameters. Clinical trial information: ISRCTN92192408 . [Table: see text]

A phase I/II study of eribulin mesilate (ERI) plus irinotecan (IRI) in children with refractory or recurrent solid tumors

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Background: ERI is an inhibitor of microtubule dynamics. IRI is used to treat pediatric sarcomas. In the pediatric preclinical testing program, ERI was well tolerated and had promising activity compared with vincristine (a common chemotherapeutic for pediatric cancers) for various solid tumors ( in vivo xenograft panels). Methods: Children with relapsed/refractory solid tumors (excluding active central nervous system tumors) were enrolled. Prior treatment with IRI was allowed. Dose escalation was conducted for 2 schedules with the primary objective (phase 1) of determining the maximum tolerated dose and the recommended phase 2 dose: (A) ERI 1.4 mg/m2 IV infusion (Days 1 + 8 of 21-day cycle) + IRI 20 or 40 mg/m2 IV infusion (Days 1–5 of 21-day cycle); (B) ERI 1.4 mg/m2 IV infusion (Days 1 + 8 of 21-day cycle) + IRI 100 or 125 mg/m2 IV infusion (Days 1 + 8 of 21-day cycle). Safety and pharmacokinetic parameters were assessed. Results: 13 patients (pts) were enrolled (median age: 9 years [range: 3–17]); 4 pts had rhabdomyosarcoma (RMS), 2 had non-RMS soft tissue sarcoma, 2 had Ewing sarcoma, 2 had hepatoblastoma, 2 had nephroblastoma, and 1 had neuroblastoma. Overall, 7 pts previously received IRI. No dose-limiting toxicities (DLTs) were reported for either schedule. At data cut-off (July 14, 2019), 4 pts (with Ewing sarcoma, neuroblastoma, RMS, or hepatoblastoma) continued treatment (A, n = 2; B, n = 2) and 9 pts discontinued treatment (primarily for radiographic progression, n = 7 [A, n = 4; B, n = 3]). All pts experienced ≥1 treatment-emergent adverse event (TEAE); the most common any grade TEAE was neutropenia (n = 10; A, n = 5; B, n = 5). 11 pts had grade ≥3 TEAEs (A, n = 6; B, n = 5); the most frequent grade ≥3 TEAE was neutropenia (n = 9; A, n = 5; B, n = 4). No pt withdrew ERI or IRI due to an AE; 3 pts had dose reductions for ERI (A, n = 1; B, n = 2) and 3 pts had dose interruption of ERI (A, n = 2; B, n = 1) due to AEs. No pt had dose reductions for IRI, and 3 pts had dose interruption of IRI (A, n = 2; B, n = 1) due to AEs. 3 deaths occurred; 2 deaths were the result of tumor progression (A, n = 1; B, n = 1), and the cause of 1 was unknown (B). 1 pt with neuroblastoma treated according to schedule A had a partial response. Systemic exposures of ERI, IRI, and SN-38 (IRI active metabolite) were similar between schedules and doses. Conclusions: No DLTs were observed. Toxicity was manageable. Administration of IRI treatment on Days 1–5 is widely used in pediatric cancers; enrollment for phase 2 is ongoing with treatment Schedule A (ERI 1.4 mg/m2 Days 1 + 8 of 21-day cycle; IRI 40 mg/m2 Days 1–5 of 21-day cycle). Clinical trial information: NCT03245450.