CD3 immunotoxin therapy of cutaneous T cell lymphoma

The recombinant CD3 immunotoxin, A-dmDT(390)-bisFv(UCHT1), composed of the catalytic and translocation domains of diphtheria toxin fused to two single chain Fv fragments of an anti-CD3epsilon monoclonal antibody was administered to five patients with cutaneous T cell lymphoma (CTCL) by eight 15 min intravenous infusions over four days. Side effects were fever, chills, nausea, hypoalbuminemia, transaminasemia and reactivation of EBV and CMV. Half-life of drug was 40 min. Anti-immunotoxin antibodies developed in all patients after two weeks. Two patients had partial remissions lasting 1 and 6+ months. The agent is undergoing further dose escalation and shows promising results in this disease.

The fusion toxin DT388IL3 composed of the catalytic and translocation domains of diphtheria toxin (DT388) linked to interleukin-3 (IL3) was administered to 6 cynomolgus monkeys which possessed cross-reactive IL3 receptors. Groups of 2 animals (1 male and 1 female) received up to 6 every other day slow intravenous infusions of 40, 60, or 100 microg/kg DT388IL3. Monkeys given 40 or 60 microg/kg showed mild or moderate transient malaise and anorexia, respectively, without evidence of organ damage by blood tests or histopathology. Animals treated at 100 microg/kg showed severe malaise and anorexia. The female monkey had moderate to severe vasculitis in multiple tissues. Necropsies were performed on the 40 microg/kg monkeys on day 14 and the 100 microg/kg monkeys on days 6 and 7. DT388IL3 plasma half-life was approximately 30 min with a peak concentration of 0.45 microg/ml or 10,000 pM (IC50 for AML blasts treated in vitro was 6 pM). Immune responses were minimal in 4 animals tested at 12 days and 2 animals tested at 30 days post treatment with anti-DT388IL3 levels < 1 microg/ml. Bone marrow aspirates were obtained on all animals at day 19 or at necropsy and revealed myeloid suppression in the females and myeloid hyperplasia in the males irrespective of dose groups. The maximal tolerated dose of 60 microg/kg for 6 doses is markedly higher than other recombinant diphtheria toxins and provides a dose level sufficient for anti-leukemic activity in vitro and in rodent models. Thus, we propose this agent is a promising drug for AML patients.

3056 Background: 17AAG (denoted KOS-953 in a novel Cremophor-based formulation) inhibits the activity of HSP90, resulting in degradation of client proteins. In vitro, 17AAG induces apoptosis of drug-sensitive and resistant MM cell lines, and tumor cells from patients with refractory MM (including bortezomib- or IMiD-resistant). In vivo, 17AAG extends the survival of mice after MM cells are injected and home to the marrow. Study objectives: define the MTD, toxicity and PK. Methods: Pts receive 17AAG (150 & 220 mg/m2) IV twice weekly for 2 out of 3 weeks. PK is performed for 17AAG and 17AG (active metabolite). Bone marrow aspirates (BMA), collected prior to drug and 4 hours following the 1st and 4th infusion, are examined for apopotosis, proliferation, pAKT, and change in HSP, IL-6 and IGF-R1 expression. PBLs are collected for assessment of change in HSP70/90. Results: 13 pts (3 F/10 M; median age 62 yrs; KPS 90; prior regimens 4, range 2–19) were enrolled in 2 dose levels. Dose limiting toxicity was observed at 220 mg/m2: a pt with liver infiltration of plasma cells had a Grade 3 elevated ALT; the pt was retreated at a lower dose but continued with grade 1–2 elevations. Other drug-related toxicity (Grade 1–2): bone pain (back, leg, rib), fatigue, diarrhea, anemia and rash. BMAs at 220 mg/m2 showed increased apoptosis (as determined by mitochondrial potential) and decreased pAKT comparing screening and Day 11 (p=0.057, both parameters). Signs of antitumor activity include: 1 pt with 93% reduction in kappa light chain; 1 pt with a minor response in IgA. Progression of disease typically occurred in extramedullary plasmacytomas, with stabilization or improvement of M-protein and KPS. Conclusions: Preliminary signs of activity in patients with advanced, heavily pre-treated MM have been seen; evaluation of 220 mg/m2 is continuing. Manageable toxicity without neuropathy is observed. PK for 17AAG in this formulation at these doses are similar compared to 17AAG in an egg-phospholipid formulation. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Kosan Biosciences Kosan Biosciences Kosan Biosciences

Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN) Is Highly BCL-2 Dependent and Sensitive to Venetoclax

Background: Symptomatic bone marrow metastasis causing myelophthisis is a rare manifestation of metastatic breast cancer, indicating a poor prognosis due to significant cytopenias. CDK4/6 inhibitors are first-line therapies for metastatic hormone-positive breast cancer but remain an unclear choice in breast cancer patients with significant cytopenias due to associated hematological adverse effects. We present a case of biopsy-proven hormone-positive breast cancer with bone marrow infiltration causing profound pancytopenia. CDK4/6 inhibitors were safely administered despite their cytopenic effects. Case Presentation: A 59-year-old female presented after an abnormal annual mammogram and biopsy showed calcifications stromal fibrosis, cyst formation, and usual ductal hyperplasia in the right upper outer quadrant. One month later, she presented to an outside hospital with gingival bleeding, epistaxis, progressive dyspnea on exertion, and generalized weakness. Labs showed severe anemia with a hemoglobin of 4.8 g/dL (baseline 12.1 g/dL), thrombocytopenia with platelets of 5 K/mm (baseline 215 K/mm), LDH of 879, reticulocyte count of 5%, and negative direct Coombs test. Peripheral smear showed no schistocytes, but showed nucleated RBCs, severely reduced platelets, and occasional giant platelets. The patient was treated for presumed ITP, and the presence of nucleated RBCs prompted bone marrow biopsy which confirmed metastatic invasive lobular carcinoma breast cancer (ER 90-95%, PR 90-95%, HER2 1+). She was discharged on letrozole 2.5 mg daily with close outpatient oncologic follow-up. One week later, she presented to our institution with persistent symptomatic anemia and thrombocytopenia. Inpatient systemic therapy was begun using dose-reduced Palbociclib (75mg) and letrozole with close CBC monitoring while also receiving packed red blood cells (goal &amp;gt;6.5) and platelet transfusions (goal &amp;gt;10). Repeat bone marrow biopsy showed extensive marrow fibrosis, but no significant hematopoietic elements. ADAMTS13 was 134%, ruling out TTP, and she was treated again for presumed ITP with dexamethasone and IVIG, Throughout the 4-week admission, her right breast mass decreased in size and she was discharged after completing 3 weeks of Palbociclib with biweekly outpatient transfusions. During follow-up, the patient’s hemoglobin and platelets slowly started to respond allowing her to become transfusion-independent and allowing dose escalation. Restaging scans 2 months after hospitalization showed an overall improvement of disease burden. The patient continued to do well for almost 18 months, however, later redeveloped visceral crisis and is responding to chemotherapy. Discussion: There is limited data on the management of breast cancer with bone marrow infiltration at presentation. A wide range of survival data in different case reports exists, ranging from 5 to 44 months. However, chemotherapy was used in these studies rather than CDK4/6 inhibitors. By far, cytopenias are the most concerning grade 3 and 4 side effect of Palbociclib. Data from the PALOMA-1 trial suggest that hematologic toxicities, specifically neutropenia, were different from those associated with cytotoxic chemotherapies and are more transient and reversible in nature. Studies have examined the in vitro mechanism of bone marrow suppression in Palbociclib versus cytotoxic chemotherapy, and its cytostatic effect on neutrophil precursors allows for hematological toxicities to be transient. With strong supportive care measures, patients in bone marrow visceral crisis can be safely treated with cytopenic CDK4/6 inhibitors. Citation Format: Nikita Dahake, Jordan Senchak, Jalil Nasibli, Jason Incorvati. Treatment with CDK4/6 Inhibitor in a Patient with Metastatic Breast Cancer Causing Myelophthisis [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-20-10.

Gemtuzumab Ozogamicin (MylotargR) as Primary Induction Therapy for Elderly Patients with Acute Myeloid Leukemia: A Phase II Trial.

Large-scale multiparameter screening has become increasingly feasible and straightforward to perform thanks to developments in technologies such as high-content microscopy and high-throughput flow cytometry. The automated toolkits for analyzing similarities and differences between large numbers of tested conditions have not kept pace with these technological developments. Thus, effective analysis of multiparameter screening datasets becomes a bottleneck and a limiting factor in unbiased interpretation of results. Here we introduce compaRe, a toolkit for large-scale multiparameter data analysis, which integrates quality control, data bias correction, and data visualization methods with a mass-aware gridding algorithm-based similarity analysis providing a much faster and more robust analyses than existing methods. Using mass and flow cytometry data from acute myeloid leukemia and myelodysplastic syndrome patients, we show that compaRe can reveal interpatient heterogeneity and recognizable phenotypic profiles. By applying compaRe to high-throughput flow cytometry drug response data in AML models, we robustly identified multiple types of both deep and subtle phenotypic response patterns, highlighting how this analysis could be used for therapeutic discoveries. In conclusion, compaRe is a toolkit that uniquely allows for automated, rapid, and precise comparisons of large-scale multiparameter datasets, including high-throughput screens.

Post Allogeneic Stem Cell Transplant Outcomes Following Response to Hypomethylating Agent Therapy in Myelodysplastic Syndromes Are Predicted By Persistent International Prognostic Scoring System-Molecular Risk

Promoter Elements of Genes Coding for Proteins and Modulation of Transcription by Estrogens and Progesterone

Splenectomy In Patients with MDS

In addition to predominant granulocytic proliferation, bone marrow morphology in Philadelphia chromosome positive (Ph1+) CML is characterized by atypical dwarf or microforms of megakaryocytes. However, following therapy with interferon-alpha 2b (IFN), these micromegakaryocytes occur less frequently. The purpose of this study was to elucidate whether the reappearance of normal megakaryocytes may be associated also with a reduction of the bcr/abl-positive cell clone. Fluorescence in-situ hybridization (FISH) technique in combination with immunomorphometry (CD61) was performed on trephine biopsies. A total of 311 CD61-positive megakaryocytes, including precursors and atypical microforms, were evaluated in pre-treatment specimens derived from 11 patients with Ph1+ CML. A specific fusion site marking the bcr/abl translocation was found in 87% of megakaryocytes which showed a size of 169 +/- 35 microns2. In untreated patients, atypical microforms (size 200 microns2) were observed in 66% of the total megakaryocytic population. Following IFN therapy 369 megakaryocytes could be analysed in sequential examinations and were found to display a significant decrease (63%) in positive fusion signals. In addition there was also a significant enhancement in average size (252 +/- 66 microns2) reflecting a reduction in the number of micromegakaryocytes (43%). These findings were particularly conspicuous in three patients with a major to complete cytogenetic remission. A normalization of megakaryocyte size following IFN therapy in CML is significantly associated with a loss of the bcr/abl translocation site and therefore indicates a (partial) recovery of normal haematopoiesis.

GD2, a disialoganglioside, is present on the surface of most neuroblastomas, as well as on some other cancers, such as melanoma and osteogenic sarcoma. The anti-GD2 antibody ch14.18 (dinutuximab) has an FDA-registered indication for use as maintenance therapy for high-risk neuroblastoma with cytokines and 13-cis-retinoic acid after myeloablative therapy. Recent studies using immunohistochemistry of tumor or tumor cells in marrow have shown that some neuroblastomas are negative for GD2. Dinutuximab and other anti-GD2 antibodies are increasingly used in combination with cytotoxic chemotherapy for treating relapsed neuroblastoma, so it is important to be able to identify patients with tumor cells with low GD2 expression, as such patients may experience toxicity but not benefit from the antibody therapy. As the most common clinical samples available for relapsed neuroblastoma are bone marrow aspirates, we developed a method to quantify dinutuximab binding density and the frequency of neuroblastoma cells positive for the antibody in bone marrow aspirates. Here, we describe a multi-color flow cytometry assay that employs non-GD2 antibodies to identify neuroblastoma cells in a mixed population (tumor, bone marrow, or blood) and an anti-GD2 antibody to quantify both the frequency and density of GD2 expression on neuroblastoma cells.

Phase II study of clinical efficacy of venetoclax in combination with azacitidine in patients with therapy related myelodysplastic syndrome (t-MDS)

Long-Term Experience with Large Granular Lymphocytic Leukemia Evolving after Solid Organ and Hematopoietic Stem Cell Transplantation

Therapy related myeloid neoplasm is directly related to previous cytotoxic chemotherapy or radiation therapy. We present a 47-year-old lady who developed therapy related myelodysplastic syndrome (MDS) 2.5 years after she received four cycles of chemotherapy and local radiation therapy for carcinoma breast. She presented with bicytopenia with trilineage dyspoiesis in the peripheral blood, bone marrow aspirate and biopsy. Fluorescent in-situ hybridization studies did not reveal any of the common abnormalities associated with MDS. A diagnosis of therapy related MDS was rendered. Different studies have shown that patients treated with alkylating agents and ionizing radiation present as MDS with a latent period of 3-10 years. Our patient developed MDS within 2.5 years of starting chemotherapy and radiotherapy and did not reveal any of the conventional cytogenetic abnormalities. It highlights the importance of simple tests like a complete blood count and peripheral blood smear examination in follow-up of the patients treated with chemotherapy.