Phase I Trial of 'Re-Priming' Radiation Therapy for Relapsed/Refractory Non-Hodgkin Lymphoma Patients in Incomplete Response after Chimeric Antigen Receptor T-Cell (CAR-T) Therapy

PURPOSE/OBJECTIVE(S)

Inpatients with relapsed/refractory non-Hodgkin lymphoma (R/R NHL) treated with CD19-directed CAR-T, only ∼40% achieve complete response (CR) by day 30 PET/CT evaluation. Of those who do not, the large majority (∼70%) ultimately fail, providing an ideal target for early therapeutic intervention to 're-prime' CAR-T. Preclinical and early clinical studies suggest potential synergy and immune augmentation when combining RT with CAR-T. Here we report the phase I results of a prospective phase I/II clinical trial hypothesizing that early salvage focal RT to poor responding sites of disease after CAR-T in R/R NHL patients is safe (phase I) and will improve conversion to CR by day 90 post-CAR-T PET/CT from 29% (historical control) to 58% (phase II).

MATERIALS/METHODS

Weopened a single-arm open-label phase I/II prospective clinical trial at our institution for R/R NHL patients treated with CD19-directed CAR-T with incomplete response on day 30 post-CAR-T PET/CT scan (defined as Lugano > = 4). The phase I component used a 'Rolling 6' design with 6 patients enrolled concurrently at the "definitive" dose level (40-50 Gy EQD2 [i.e., 30 Gy in 5 fractions], with de-escalation to "palliative" dose level (20-32.5 Gy EQD2 [i.e., 20 Gy in 5 fractions]) if >2 dose-limiting toxicities (DLT) observed. Hypofractionated regimens (i.e., 5 fractions) directed only to residual FDG-avid disease were recommended to minimize lymphopenia and potentially result in a more favorable immune microenvironment. DLT rate was defined within 60 days of RT by CTCAE v5.0 grade 4+ hematologic, grade 3+ dermatitis/burn, pneumonitis, enteritis, or other toxicity attributable to RT, as well as new grade 3+ cytokine release syndrome (CRS) per ASTCT consensus guidelines or grade 3+ neurotoxicity per ASTCT ICANS consensus guidelines for adults.

RESULTS

BetweenApril 2021 and July 2022, 6 patients were enrolled. All 6 patients had diffuse large B-cell lymphoma (DLBCL), with 3/6 (50%) transformed from low-grade follicular lymphoma. 2/6 had primary refractory DLBL, while the other 4/6 had median 2.5 lines of treatment prior to CAR-T. No patient had prior RT to a site of residual FDG-avid disease on day 30 post-CAR-T PET/CT. 5/6 patients were treated to 30 Gy in 5 fractions, with the remainder patient treated to 36 Gy in 10 fractions. No grade 3+ DLTs related to RT were observed in the 60-day post-RT period. RT related toxicities included grad 1 alopecia, grade 1 radiation pneumonitis, grade 1 nausea & vomiting, and grade 2 skin infection.

CONCLUSION

Early salvage focal "definitive" dose RT to sites of incomplete response on day 30 post-CAR-T PET/CT for R/R/ NHL patients was safe with no de-escalation of dose needed. This dose will used in the subsequent phase II component of the trial.

Acute myeloid leukemia with RAM immunophenotype presenting with extensive mesenteric and retroperitoneal lymphadenopathy: A case report and review of the literature

Acute myeloid leukemia (AML) with RAM immunophenotype is a rare recently described AML subtype. It is defined by blasts with strong expression of CD56 and weak to absent expression of CD45, HLA-DR....., and CD38 and characterized by significantly worse outcome [1]. Little is known about the clinical presentation and this immunophenotype is not widely recognized in clinical practice. We describe a case of AML with RAM immunophenotype in a 5-year-old male patient with a unique presentation, including extensive mesenteric and retroperitoneal lymphadenopathy. Diagnostic studies included bilateral bone marrow and lymph node biopsies, flow cytometry, cytogenetics, fluorescence in-situ hybridization (FISH), and next generation sequencing. Bone marrow biopsy revealed >90% blasts, positive for CD34, CD117, and CD56 by flow cytometry and immunohistochemistry. Next generation sequencing revealed BCOR loss and CBFA2T3-GLIS2 fusion. Following induction chemotherapy, bone marrow biopsy showed residual disease and a stem cell transplant was performed. The patient relapsed three months after transplant and subsequently passed away eleven months after initial diagnosis. Limited literature is available describing this newly identified AML subset. The RAM immunophenotype has been identified as an independent prognostic factor for relapse rate and overall and disease-free survival [1]. Few case reports are available to characterize the genetic profile, typical presentation, and clinical course of patients with this unique immunophenotype.

Colony-stimulating factor 3 receptor gene (CSF3R) T618I mutated chronic myelomonocytic leukemia: A proliferative subtype with a distinct mutational profile

Introduction/Objective

Chronic myelomonocytic leukemia (CMML) is a myeloid neoplasm characterized by sustained monocytosis, ranging from cytopenia with a dysplastic subtype to leukocytosis with a proliferative subtype, with a typical mutational profile involving TET2, ASXL1, and SRSF2. Mutation in colony-stimulating factor 3 receptor gene (CSF3R) is commonly associated with chronic neutrophilic leukemia (CNL) but exceedingly rare in CMML, particularly CSF3R T618I (~10 cases described, ~30 cases of CSF3R non-T618I mutations). We report a case of CSF3R T618I mutated CMML and compare the clinicopathologic features to reported CMML cases with and without CSF3R T618I mutations.

Methods/Case Report

A 27-year-old woman presented for evaluation of leukocytosis, sustained monocytosis, and anemia. Peripheral blood (PB) revealed leukocytosis (white cell count 35x109/L), left-shifted and dysplastic neutrophils (myelocytes and metamyelocytes, 5%), absolute and relative monocytosis (7x109/L, 29%), anemia (Hgb 4.3 g/dL), and thrombocytopenia. Bone marrow aspirate and core biopsy demonstrated a hypercellular marrow with increased myeloblasts (~3%, immunophenotypically aberrant by flow cytometry), increased myelomonocytic cells, and multilineage dysplasia, including ring sideroblasts and hypolobated megakaryocytes. Cytogenetic and molecular studies revealed a normal karyotype and mutations in CSF3R T618I, ASXL1, SETBP1, BCORL1, KRAS, and PTPN11. Despite the presence of a CSF3R T618I mutation, CMML was diagnosed given marked monocytosis, left- shifted neutrophils in PB, multilineage dysplasia, and immunophenotypically aberrant myeloblasts.

Results (if a Case Study enter NA)

NA

Conclusion

Our case demonstrates clinicopathological features similar to those of reported CSF3R T618I mutated CMML, i.e., a proliferative subtype and less likely to have co-occurring mutations in TET2 or SRSF2, which is distinct from CSF3R non-T618I mutated CMML; the latter often has a dysplastic subtype and mutational profile of frequent TET2 and SRSF2 mutations, similar to CSF3R unmutated CMML. While additional cases with this unusual mutation need to be studied to arrive at a more definitive conclusion, the CSF3R T618I mutation seems to define a unique proliferative subtype CMML with a distinct mutational profile.