ALK-positive histiocytosis: a new clinicopathologic spectrum highlighting neurologic involvement and responses to ALK inhibition.

ALK-positive histiocytosis is a rare subtype of histiocytic neoplasm first described in 2008 in 3 infants with multisystemic disease involving the liver and hematopoietic system. This entity has subsequently been documented in case reports and series to occupy a wider clinicopathologic spectrum with recurrent KIF5B-ALK fusions. The full clinicopathologic and molecular spectra of ALK-positive histiocytosis remain, however, poorly characterized. Here, we describe the largest study of ALK-positive histiocytosis to date, with detailed clinicopathologic data of 39 cases, including 37 cases with confirmed ALK rearrangements. The clinical spectrum comprised distinct clinical phenotypic groups: infants with multisystemic disease with liver and hematopoietic involvement, as originally described (Group 1A: 6/39), other patients with multisystemic disease (Group 1B: 10/39), and patients with single-system disease (Group 2: 23/39). Nineteen patients of the entire cohort (49%) had neurologic involvement (7 and 12 from Groups 1B and 2, respectively). Histology included classic xanthogranuloma features in almost one-third of cases, whereas the majority displayed a more densely cellular, monomorphic appearance without lipidized histiocytes but sometimes more spindled or epithelioid morphology. Neoplastic histiocytes were positive for macrophage markers and often conferred strong expression of phosphorylated extracellular signal-regulated kinase, confirming MAPK pathway activation. KIF5B-ALK fusions were detected in 27 patients, whereas CLTC-ALK, TPM3-ALK, TFG-ALK, EML4-ALK, and DCTN1-ALK fusions were identified in single cases. Robust and durable responses were observed in 11/11 patients treated with ALK inhibition, 10 with neurologic involvement. This study presents the existing clinicopathologic and molecular landscape of ALK-positive histiocytosis and provides guidance for the clinical management of this emerging histiocytic entity.

Efficacy and safety of nivolumab combined with brentuximab vedotin after nivolumab monotherapy failure in patients with relapsed and refractory classic Hodgkin lymphoma.

OBJECTIVES: Therapy of patients with relapsed and refractory classic Hodgkin lymphoma (r/r cHL) after PD-1 inhibitors failure remains an unresolved issue. The aim of this study was to evaluate the efficacy and safety of the combination of nivolumab with brentuximab vedotin (Nivo + BV) after nivolumab monotherapy failure. METHODS: This study retrospectively analyzed 21 patients with r/r cHL who were treated with the combination of Nivo + BV after Nivo failure. The response was evaluated by PET-CT scan according to the LYRIC criteria. Adverse events (AEs) were assessed according to NCI CTCAE v.4.03. RESULTS: Median follow-up was 19 (9-47) months. The ORR was 57%. The median OS was not reached, 24 month OS was 80% (95% CI 50-93%). Median PFS was 12 months with 24 month PFS of 31% (95% CI 12-53%). Any grade AEs were observed in 12 patients (63%), 3-4 grade AEs in 2 patients (10%). Allogeneic hematopoietic stem cell transplantation (allo-HSCT) after Nivo + BV was performed in 8 (38%) patients. The median time between Nivo + BV and allo-HSCT was 8 (5-21) months. CONCLUSIONS: Combination of Nivo + BV in r/r cHL after nivolumab monotherapy failure is potentially an effective and safe approach.

Nivolumab discontinuation and retreatment in patients with relapsed or refractory Hodgkin lymphoma.

Immune checkpoint inhibitors (ICI) have demonstrated high therapeutic efficacy in relapsed or refractory classical Hodgkin lymphoma (r/r cHL). Nevertheless, despite the accumulated data, the question of the ICI therapy duration and efficacy of nivolumab retreatment remains unresolved. In this retrospective study, in a cohort of 23 adult patients with r/r cHL who discontinued nivolumab in complete response (CR), the possibility of durable remission achievement (2-year PFS was 55.1%) was demonstrated. Retreatment with nivolumab has demonstrated efficacy with high overall response rate (ORR) and CR (67% and 33.3% respectively). At the final analysis, all patients were alive with median PFS of 16.5 months. Grade 3-4 adverse events (AEs) were reported in 36% of patients, and there was no deterioration in terms of nivolumab retreatment-associated complications.

A Study of Safety and Efficacy of Nivolumab and Bendamustine (NB) in Patients With Relapsed/Refractory Hodgkin Lymphoma After Nivolumab Monotherapy Failure.

This single-center prospective clinical trial evaluated the combination of nivolumab plus bendamustine (NB) as a salvage regimen in classical Hodgkin lymphoma patients after failure of nivolumab monotherapy. A total of 30 patients received nivolumab (3 mg/kg) on D1,14 and bendamustine (90 mg/m2) on D1, 2 of a 28-day cycle for up to 3 cycles. The ORR was 87% with 57% CR, 30% PR. With median follow-up of 25 months, the estimated 2-year OS was 96,7% (95% CI, 90.2%-100%), PFS was 23,3% (95% CI, 8.2%-38.4%) median PFS was 10.2 months (95% CI, 7.7-14.2 months) with median DOR 6.6 months (95% CI 3.9-11.6 months). Ten patients (33.3%) experienced grade 3 to 4 AE during therapy. Infections were most common AEs of the combined therapy. NB was a highly efficient salvage regimen in relapsed/refractory cHL with a manageable toxicity profile and modest potential for achievement of long-term remission. Registered at www.clinicaltrials.gov (#NCT0334365).

A Phase 2 Study of Nivolumab Using a Fixed Dose of 40 mg (Nivo40) in Patients With Relapsed/Refractory Hodgkin Lymphoma.

The introduction of nivolumab has changed the landscape of relapsed/refractory classical Hodgkin lymphoma (r/r cHL) treatment. Despite its clinical importance, this therapy may remain inaccessible for a significant number of patients worldwide, especially in low-income countries, due to its high cost. The results of pharmacokinetic analysis and clinical observations suggest the potential efficacy of low dose nivolumab in r/r cHL patients. The aim of this trial was to assess the efficacy and safety of nivolumab at a fixed dose of 40 mg in patients with r/r cHL. The study included 30 patients with r/r cHL, treated with 40 mg nivolumab every 2 weeks. The median dose of nivolumab per kilogram bodyweight was 0.59 mg/kg (0.4-1 mg/kg). Median follow up was 19.2 months (range 12.7-25.4). The objective response rate was 70%, with 13 (43.3%) patients achieving a complete response. Median PFS was 18.4 months (95% CI, 11.3 to 18.5 months) with 18-month PFS of 53.6% (95% CI, 32%-71%). At the time of analysis, 96.7% of patients were alive with a median OS not reached. Severe (grade 3-5) adverse events were observed in 4 patients (13.3%). Nivolumab in a fixed dose of 40 mg was efficient in patients with r/r cHL, independent from dose per kg bodyweight. The results of this study are in good agreement with previously reported data and create a rationale for further studies aimed to define the optimal dosing regimen of nivolumab for the treatment of r/r cHL. Registered at www.clinicaltrials.gov (NCT03343665).