Naxitamab combined with granulocyte-macrophage colony-stimulating factor as consolidation for high-risk neuroblastoma patients in complete remission.

BACKGROUND: Naxitamab is a humanized anti-disialoganglioside (GD2) monoclonal antibody approved for treatment of bone/bone marrow refractory high-risk neuroblastoma (HR-NB). Compassionate use (CU) expanded access program at Hospital Sant Joan de Deu permitted treatment of patients in complete remission (CR). We here report the survival, toxicity, and relapse pattern of patients in first or second CR treated with naxitamab and sargramostim (GM-CSF). PROCEDURE: Seventy-three consecutive patients with HR-NB (stage M at age >18 months or MYCN-amplified stages L1/L2 at any age) were treated in first or second CR. Treatment comprised five cycles of subcutaneous (SC) GM-CSF for 5 days at 250 µg/m2 /day (days -4 to 0), followed by naxitamab + SC GM-CSF for 5 days at 500 µg/m2 /day (days 1-5). Naxitamab was infused over 30 minutes at 3 mg/kg/day, days 1, 3, and 5, outpatient. RESULTS: Fifty-five patients were in first CR and 18 in second CR. Seventeen patients had MYCN-amplified NB and 11 detectable minimal residual disease in the bone marrow. Fifty-eight (79.5%) patients completed therapy. Four (5%) experienced grade 4 toxicities and 10 (14%) early relapse. Three-year event-free survival (EFS) 58.4%, 95% CI = (43.5%, 78.4%) and overall survival (OS) 82.4%, 95% CI = (66.8%, 100%). First CR patients 3-year EFS 74.3%, 95% CI = (62.7%, 88.1%), and OS 91.6%, 95% CI = (82.4%, 100%). EFS is significantly different between first and second CR (p = .0029). The pattern of relapse is predominantly (75%) of an isolated organ, mainly bone (54%). Univariate Cox models show prior history of relapse as the only statistically significant predictor of EFS but not OS. CONCLUSIONS: Consolidation with naxitamab and GM-CSF resulted in excellent survival rates for HR-NB patients in CR.

Outcome of children with relapsed or refractory neuroblastoma: A meta-analysis of ITCC/SIOPEN European phase II clinical trials.

BACKGROUND: Few randomized trials have been conducted in children with relapsed/refractory neuroblastoma and data about outcomes including progression-free survival (PFS) in these patients are scarce. PROCEDURE: A meta-analysis of three phase II studies of children with relapsed/refractory neuroblastoma conducted in Europe (temozolomide, topotecan-vincristine-doxorubicin and topotecan-temozolomide) was performed. Individual patient data with extended follow-up were collected from the trial databases after publication to describe trial outcomes (response rate, clinical benefit ratio, duration of treatment, PFS, and overall survival [OS]). Characteristics of subjects with relapsed/refractory neuroblastoma were compared. RESULTS: Data from 71 children and adolescents with relapsed/refractory neuroblastoma were collected. Response definitions were not homogeneous in the three trials. Patients were on study for a median of 3.5 months (interquartile range [IQR] 1.9-6.2). Of those, 35.2% achieved a complete or partial response, 26.3% experienced a response after more than two cycles, and 23.9% received more than six cycles. Median PFS from study entry for all, refractory, and relapsed patients was 6.4 ± 1.0, 12.5 ± 6.8, and 5.7 ± 1.0 months, respectively (P = 0.006). Median OS from study entry for all, refractory, and relapsed patients was 16.1 ± 4.3, 27.9 ± 20.2, and 11.0 ± 1.6 months, respectively (P = 0.03). CONCLUSIONS: Baseline data for response rate, clinical benefit ratio, duration of treatment, PFS, and OS were provided. Two subpopulations (relapsed/refractory) were clearly distinct and should be included in the interpretation of all trials. These results should help informing the design of forthcoming studies in relapsed/refractory neuroblastoma.

Desensitizing the autonomic nervous system to mitigate anti-GD2 monoclonal antibody side effects.

Background: Anti-GD2 monoclonal antibodies (mAbs) have shown to improve the overall survival of patients with high-risk neuroblastoma (HR-NB). Serious adverse events (AEs), including pain, within hours of antibody infusion, have limited the development of these therapies. In this study, we provide evidence of Autonomic Nervous System (ANS) activation as the mechanism to explain the main side effects of anti-GD2 mAbs. Methods: Through confocal microscopy and computational super-resolution microscopy experiments we explored GD2 expression in postnatal nerves of infants. In patients we assessed the ANS using the Sympathetic Skin Response (SSR) test. To exploit tachyphylaxis, a novel infusion protocol (the Step-Up) was mathematically modelled and tested. Results: Through confocal microscopy, GD2 expression is clearly visible in the perineurium surrounding the nuclei of nerve cells. By computational super-resolution microscopy experiments we showed the selective expression of GD2 on the cell membranes of human Schwann cells in peripheral nerves (PNs) significantly lower than on NB. In patients, changes in the SSR were observed 4 minutes into the anti-GD2 mAb naxitamab infusion. SSR latency quickly shortened followed by gradual decrease in the amplitude before disappearance. SSR response did not recover for 24 hours consistent with tachyphylaxis and absence of side effects in the clinic. The Step-Up protocol dissociated on-target off-tumor side effects while maintaining serum drug exposure. Conclusion: We provide first evidence of the ANS as the principal non-tumor target of anti-GD2 mAbs in humans. We describe the development and modeling of the Step-Up protocol exploiting the tachyphylaxis phenomenon we demonstrate in patients using the SSR test.

Novel infusion strategy reduces severe adverse events caused by the anti-GD2 monoclonal antibody naxitamab.

Introduction: Anti-disialoganglioside 2 (anti-GD2) monoclonal antibodies (mAbs) are associated with Grade ≥3 (≥G3) adverse events (AEs) such as severe pain, hypotension, and bronchospasm. We developed a novel method of administering the GD2-binding mAb naxitamab, termed "Step-Up" infusion (STU), to reduce the risk of AEs of severe pain, hypotension, and bronchospasm. Methods: Forty-two patients with GD2-positive tumors received naxitamab under "compassionate use" protocols and administered via either the standard infusion regimen (SIR) or the STU regimen. The SIR comprises a 60-min infusion of 3 mg/kg/day on Day 1 of cycle 1 and a 30- to 60-min infusion on Day 3 and Day 5, as tolerated. The STU regimen uses a 2-h infusion on Day 1, initiated at a rate of 0.06 mg/kg/h during 15 min (0.015 mg/kg) and which increases gradually to a cumulative dose of 3 mg/kg; on Days 3 and 5, the 3-mg/kg dose is initiated at 0.24 mg/kg/h (0.06 mg/kg) and delivered in 90 min according to the same gradual-increase strategy. AEs were graded according to Common Terminology Criteria for Adverse Events version 4.0. Results: The frequency of infusions with an associated G3 AE was reduced from 8.1% (23/284 infusions) with SIR to 2.5% (5/202 infusions) with STU. The odds of an infusion being associated with a G3 AE reduced by 70.3% with STU vs. SIR (odds ratio: 0.297; p = 0.037). Mean serum naxitamab levels pre- and post-STU (11.46 µg/ml pre-infusion; 100.95 µg/ml post-infusion) were within the range reported for SIR. Discussion: The comparable pharmacokinetics of naxitamab during SIR and STU may indicate that switching to STU reduces G3 AEs without impact on efficacy.

Early Salvage Chemo-Immunotherapy with Irinotecan, Temozolomide and Naxitamab Plus GM-CSF (HITS) for Patients with Primary Refractory High-Risk Neuroblastoma Provide the Best Chance for Long-Term Outcomes.

Patients with high-risk neuroblastoma (HR-NB) who are unable to achieve a complete response (CR) to induction therapy have worse outcomes. We investigated the combination of humanized anti-GD2 mAb naxitamab (Hu3F8), irinotecan (I), temozolomide (T), and sargramostim (GM-CSF)-HITS-against primary resistant HR-NB. Eligibility criteria included having a measurable chemo-resistant disease at the end of induction (EOI) treatment. Patients were excluded if they had progressive disease (PD) during induction. Prior anti-GD2 mAb and/or I/T therapy was permitted. Each cycle, administered four weeks apart, comprised Irinotecan 50 mg/m2/day intravenously (IV) plus Temozolomide 150 mg/m2/day orally (days 1-5); naxitamab 2.25 mg/kg/day IV on days 2, 4, 8 and 10, (total 9 mg/kg or 270 mg/m2 per cycle), and GM-CSF 250 mg/m2/day subcutaneously was used (days 6-10). Toxicity was measured using CTCAE v4.0 and responses through the modified International Neuroblastoma Response Criteria (INRC). Thirty-four patients (median age at treatment initiation, 4.9 years) received 164 (median 4; 1-12) HITS cycles. Toxicities included myelosuppression and diarrhea, which was expected with I/T, and pain and hypertension, expected with naxitamab. Grade ≥3-related toxicities occurred in 29 (85%) of the 34 patients; treatment was outpatient. The best responses were CR = 29% (n = 10); PR = 3% (n = 1); SD = 53% (n = 18); PD = 5% (n = 5). For cohort 1 (early treatment), the best responses were CR = 47% (n = 8) and SD = 53% (n = 9). In cohort 2 (late treatment), the best responses were CR = 12% (n = 2); PR = 6% (n = 1); SD = 53% (n = 9); and PD = 29% (n = 5). Cohort 1 had a 3-year OS of 84.8% and EFS 54.4%, which are statistically significant improvements (EFS p = 0.0041 and OS p = 0.0037) compared to cohort 2. In conclusion, naxitamab-based chemo-immunotherapy is effective against primary chemo-resistant HR-NB, increasing long-term outcomes when administered early during the course of treatment.

Naxitamab Combined with Granulocyte-Macrophage Colony-Stimulating Factor as Consolidation for High-Risk Neuroblastoma Patients in First Complete Remission under Compassionate Use-Updated Outcome Report.

Naxitamab is an anti-GD2 antibody approved for the treatment of relapsed/refractory HR-NB. We report the survival, safety, and relapse pattern of a unique set of HR-NB patients consolidated with naxitamab after having achieved first CR. Eighty-two patients were treated with 5 cycles of GM-CSF for 5 days at 250 µg/m2/day (-4 to 0), followed by GM-CSF for 5 days at 500 µg/m2/day (1-5) and naxitamab at 3 mg/kg/day (1, 3, 5), on an outpatient basis. All patients but one were older than 18 months at diagnosis and had stage M; 21 (25.6%) pts had MYCN-amplified (A) NB; and 12 (14.6%) detectable MRD in the BM. Eleven (13.4%) pts had received high-dose chemotherapy and ASCT and 26 (31.7%) radiotherapy before immunotherapy. With a median follow-up of 37.4 months, 31 (37.8%) pts have relapsed. The pattern of relapse was predominantly (77.4%) an isolated organ. Five-year EFS and OS were 57.9% (71.4% for MYCN A) 95% CI = (47.2, 70.9%); and 78.6% (81% for MYCN A) 95% CI = (68.7%, 89.8%), respectively. EFS showed significant differences for patients having received ASCT (p = 0.037) and pre-immunotherapy MRD (p = 0.0011). Cox models showed only MRD as a predictor of EFS. In conclusion, consolidation with naxitamab resulted in reassuring survival rates for HR-NB patients after end-induction CR.