North American Blastic Plasmacytoid Dendritic Cell Neoplasm Consortium: position on standards of care and areas of need.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy with historically poor outcomes and no worldwide consensus treatment approach. Unique among most hematologic malignancies for its frequent cutaneous involvement, BPDCN can also invade other extramedullary compartments, including the central nervous system. Generally affecting older adults, many patients are unfit to receive intensive chemotherapy, and although hematopoietic stem cell transplantation is preferred for younger, fit individuals, not all are eligible. One recent therapeutic breakthrough is that all BPDCNs express CD123 (IL3Rα) and that this accessible surface marker can be pharmacologically targeted. The first-in-class agent for BPDCN, tagraxofusp, which targets CD123, was approved in December 2018 in the United States for patients with BPDCN aged ≥2 years. Despite favorable response rates in the frontline setting, many patients still relapse in the setting of monotherapy, and outcomes in patients with relapsed/refractory BPDCN remain dismal. Therefore, novel approaches targeting both CD123 and other targets are actively being investigated. To begin to formally address the state of the field, we formed a new collaborative initiative, the North American BPDCN Consortium (NABC). This group of experts, which includes a multidisciplinary panel of hematologists/oncologists, hematopoietic stem cell transplant physicians, pathologists, dermatologists, and pediatric oncologists, was tasked with defining the current standard of care in the field and identifying the most important research questions and future directions in BPDCN. The position findings of the NABC's inaugural meetings are presented herein.

A Case of Recurrent Localized Pulmonary Nodular Light Chain Amyloidosis Treated with Daratumumab plus CyBorD.

INTRODUCTION: Nodular pulmonary amyloidosis (NPA) is a localized form of light chain (AL) amyloidosis often found incidentally and typically has an indolent and benign disease course treated with resection or local excision. We present a patient with recurrent localized AL amyloidosis who required further treatment. CASE PRESENTATION: A 63-year-old female with monoclonal gammopathy of undetermined significance (MGUS) was found to have pulmonary AL amyloid on wedge resection and later had recurrence. The patient did not have signs of clonal plasma cell proliferation or systemic AL amyloid. She was treated with daratumumab, cyclophosphamide, bortezomib, and dexamethasone. After initiation of treatment, the patient has had significant hematologic and radiographic response. CONCLUSION: The patient had NPA recurrence with organ dysfunction without systemic disease. Because the presentation of recurrent pulmonary AL amyloidosis is rare, there is no published evidence on treatment. However, the patient has had hematologic and radiographic improvement after initiating treatment with a systemic protocol.

Autophagy and Apoptosis: Current Challenges of Treatment and Drug Resistance in Multiple Myeloma.

Over the past two decades, the natural history of multiple myeloma (MM) has evolved dramatically, owing primarily to novel agents targeting MM in the bone marrow microenvironment (BMM) pathways. However, the mechanisms of resistance acquisition remain a mystery and are poorly understood. Autophagy and apoptosis are tightly controlled processes and play a critical role in the cell growth, development, and survival of MM. Genetic instability and abnormalities are two hallmarks of MM. During MM progression, plasma malignant cells become genetically unstable and activate various signaling pathways, resulting in the overexpression of abnormal proteins that disrupt autophagy and apoptosis biological processes. Thus, achieving a better understanding of the autophagy and apoptosis processes and the proteins that crosslinked both pathways, could provide new insights for the MM treatment and improve the development of novel therapeutic strategies to overcome resistance. This review presents a sufficient overview of the roles of autophagy and apoptosis and how they crosslink and control MM progression and drug resistance. Potential combination targeting of both pathways for improving outcomes in MM patients also has been addressed.

Bruton's Tyrosine Kinase Targeting in Multiple Myeloma.

Multiple myeloma (MM), a clonal plasma cell disorder, disrupts the bones' hematopoiesis and microenvironment homeostasis and ability to mediate an immune response against malignant clones. Despite prominent survival improvement with newer treatment modalities since the 2000s, MM is still considered a non-curable disease. Patients experience disease recurrence episodes with clonal evolution, and with each relapse disease comes back with a more aggressive phenotype. Bruton's Tyrosine Kinase (BTK) has been a major target for B cell clonal disorders and its role in clonal plasma cell disorders is under active investigation. BTK is a cytosolic kinase which plays a major role in the immune system and its related malignancies. The BTK pathway has been shown to provide survival for malignant clone and multiple myeloma stem cells (MMSCs). BTK also regulates the malignant clones' interaction with the bone marrow microenvironment. Hence, BTK inhibition is a promising therapeutic strategy for MM patients. In this review, the role of BTK and its signal transduction pathways are outlined in the context of MM.

The Effect of the Histone Deacetylase Inhibitor Suberoylanilide Hydroxamic Acid and Paclitaxel Treatment on Full-Thickness Wound Healing in Mice.

INTRODUCTION: Neoadjuvant chemotherapy prior to lumpectomy or mastectomy for breast cancer challenges wound healing. Suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, has been shown to work synergistically with paclitaxel in vitro and in preclinical studies. In addition, our laboratory has demonstrated that SAHA treatment decreases paclitaxel-associated stem cell toxicity, modulates inflammatory response, and promotes wound healing in injured fibroblast cells. Our goal was to determine if combined SAHA and paclitaxel treatment would improve wound healing in an in vivo full-thickness murine model, without altering antitumor effect. METHODS: Thirty-two nude athymic mice received intraperitoneal injections of paclitaxel (20 mg/kg), SAHA (25 mg/kg), paclitaxel + SAHA (20 mg/kg + 25 mg/kg), or no treatment for 2 weeks prior to surgery. Under general anesthesia, 8-mm full-thickness dorsal wounds were created in all animals, and a silicone splint was attached to minimize wound contraction. The wounds were measured twice a week with a surgical caliper until healing was complete. To evaluate the in vivo effect of drug treatment, 16 athymic nude mice with MDA-MB-231 xenografts received the treatments described previously, following which tumor volumes were compared between groups. RESULTS: Average wound healing time was prolonged in mice treated with paclitaxel (20 ± 1.9 days), and combination SAHA + paclitaxel therapy improved average wound healing time (17.0 ± 1.8 days). In the xenograft model, the antitumor effect of SAHA and paclitaxel (average tumor volume 43.9 ± 34.1 mm) was greater than paclitaxel alone (105.8 ± 73.8 mm). CONCLUSIONS: The addition of SAHA to taxane chemotherapy improves the therapeutic effect on triple-negative breast cancer while decreasing the detrimental effect of paclitaxel on wound healing. This may have substantial implications on improving outcomes in breast reconstruction following chemotherapy.

Enrichment of human prostate cancer cells with tumor initiating properties in mouse and zebrafish xenografts by differential adhesion.

BACKGROUND: Prostate tumor-initiating cells (TICs) have intrinsic resistance to current therapies. TICs are commonly isolated by cell sorting or dye exclusion, however, isolating TICs from limited primary prostate cancer (PCa) tissues is inherently inefficient. We adapted the collagen adherence feature to develop a combined immunophenotypic and time-of-adherence assay to identify human prostate TICs. METHODS: PCa cells from multiple cell lines and primary tissues were allowed to adhere to several matrix molecules, and fractions of adherent cells were examined for their TIC properties. RESULTS: Collagen I rapidly-adherent PCa cells have significantly higher clonogenic, migration, and invasion abilities, and initiated more tumor xenografts in mice when compared to slowly-adherent and no-adherent cells. To determine the relative frequency of TICs among PCa cell lines and primary PCa cells, we utilized zebrafish xenografts to define the tumor initiation potential of serial dilutions of rapidly-adherent α2ß1(hi) /CD44(hi) cells compared to non-adherent cells with α2ß1(low) /CD44(low) phenotype. Tumor initiation from rapidly-adherent α2ß1(hi) /CD44(hi) TICs harboring the TMPRSS2:ERG fusion generated xenografts comprising of PCa cells expressing Erg, AMACR, and PSA. Moreover, PCa-cell dissemination was consistently observed in the immune-permissive zebrafish microenvironment from as-few-as 3 rapidly-adherent α2ß1(hi) /CD44(hi) cells. In zebrafish xenografts, self-renewing prostate TICs comprise 0.02-0.9% of PC3 cells, 0.3-1.3% of DU145 cells, and 0.22-14.3% of primary prostate adenocarcinomas. CONCLUSION: Zebrafish PCa xenografts were used to determine that the frequency of prostate TICs varies among PCa cell lines and primary PCa tissues. These data support a paradigm of utilizing zebrafish xenografts to evaluate novel therapies targeting TICs in prostate cancer.

Isolated AL Amyloidosis of the Colon: A Rare Presentation.

Amyloidosis is a group of rare deposition diseases marked by the accumulation of abnormal fibrillar proteins in the extracellular space of various tissues. In both AL and AA amyloidosis, the most common variants, isolated involvement to any one organ is uncommon and involvement to the colon alone is especially rare. We present the case of a patient who was initially found to have AL amyloidosis on prior screening colonoscopy that was reconfirmed several years with repeat evaluation for chronic constipation. This disease process is often insidious and can be overlooked by providers given the lack of overwhelming symptoms.

Discovering Potential in Non-Cancer Medications: A Promising Breakthrough for Multiple Myeloma Patients.

MM is a common type of cancer that unfortunately leads to a significant number of deaths each year. The majority of the reported MM cases are detected in the advanced stages, posing significant challenges for treatment. Additionally, all MM patients eventually develop resistance or experience relapse; therefore, advances in treatment are needed. However, developing new anti-cancer drugs, especially for MM, requires significant financial investment and a lengthy development process. The study of drug repurposing involves exploring the potential of existing drugs for new therapeutic uses. This can significantly reduce both time and costs, which are typically a major concern for MM patients. The utilization of pre-existing non-cancer drugs for various myeloma treatments presents a highly efficient and cost-effective strategy, considering their prior preclinical and clinical development. The drugs have shown promising potential in targeting key pathways associated with MM progression and resistance. Thalidomide exemplifies the success that can be achieved through this strategy. This review delves into the current trends, the challenges faced by conventional therapies for MM, and the importance of repurposing drugs for MM. This review highlights a noncomprehensive list of conventional therapies that have potentially significant anti-myeloma properties and anti-neoplastic effects. Additionally, we offer valuable insights into the resources that can help streamline and accelerate drug repurposing efforts in the field of MM.

Correction to: Isolated AL Amyloidosis of the Colon: A Rare Presentation.

[This corrects the article DOI: 10.14309/crj.0000000000001277.].

KS18, a Mcl-1 inhibitor, improves the effectiveness of bortezomib and overcomes resistance in refractory multiple myeloma by triggering intrinsic apoptosis.

Despite a record number of clinical studies investigating various anti-myeloma treatments, the 5-year survival rate for multiple myeloma (MM) patients in the US is only 55%, and almost all patients relapse. Poor patient outcomes demonstrate that myeloma cells are "born to survive" which means they can adapt and evolve following treatment. Thus, new therapeutic approaches to combat survival mechanisms and target treatment resistance are required. Importantly, Mcl-1, anti-apoptotic protein, is required for the development of MM and treatment resistance. This study looks at the possibility of KS18, a selective Mcl-1 inhibitor, to treat MM and overcome resistance. Our investigation demonstrates that KS18 effectively induces cell death in MM by dual regulatory mechanisms targeting the Mcl-1 protein at both transcriptional and post-translational levels. Specifically, KS18 suppresses Mcl-1 activation via STAT-3 pathway and promotes Mcl-1 phosphorylation/ubiquitination/proteasome-dependent protein degradation (UPS). Significantly, KS18 triggered caspase-dependent apoptosis in MM patient samples and bortezomib-resistant cells, synergizing with venetoclax to boost apoptosis. KS18 promises to overcome bortezomib and venetoclax resistance and re-sensitize myeloma cells to chemotherapy. Furthermore, the study shows the tremendous impact of KS18 in inhibiting colony formation in bortezomib-resistant cells and demonstrates significant tumor shrinkage in KS18-treated NSG mice without notable toxicity signs after 4 weeks of therapy with a single acceptable dose each week, indicating its powerful anti-neoplastic and anti-resistance characteristics. This study strongly implies that KS18 may treat MM and provide new hope to patients who are experiencing recurrence or resistance.

Pathways to therapy resistance: The sheltering effect of the bone marrow microenvironment to multiple myeloma cells.

Multiple Myeloma (MM) is a malignant expansion of plasma cells in the bone marrow (BM), resulting in a disease characterized by symptoms of end organ damage from light chain secretion, crowding of the BM, and bone lesions. Although the past two decades have been characterized by numerous novel therapies emerging, the disease remains incurable due to intrinsic or acquired drug resistance. A major player in MM's drug resistance arises from its intimate relationship with the BM microenvironment (BMME). Through stress-inducing conditions, soluble messengers, and physical adhesion to BM elements, the BMME activates numerous pathways in the myeloma cell. This not only propagates myeloma progression through survival and growth signals, but also specific mechanisms to circumvent therapeutic actions. In this review, we provide an overview of the BMME, the role of individual components in MM survival, and various therapy-specific resistance mechanisms reported in the literature.

Past, Present, and a Glance into the Future of Multiple Myeloma Treatment.

Multiple myeloma (MM) is a challenging hematological cancer which typically grows in bone marrow. MM accounts for 10% of hematological malignancies and 1.8% of cancers. The recent treatment strategies have significantly improved progression-free survival for MM patients in the last decade; however, a relapse for most MM patients is inevitable. In this review we discuss current treatment, important pathways for proliferation, survival, immune suppression, and resistance that could be targeted for future treatments.

Multifocal Follicular Lymphoma Isolated to the Gastrointestinal Tract: A Rare Finding.

Follicular lymphoma (FL) is a common form of non-Hodgkin lymphoma. Although extranodal involvement of the gastrointestinal (GI) tract is common in lymphomas, primary GI-FL confined to the GI tract is relatively rare. The disease process is typically indolent in nature and usually incidentally found. Among this subset of patients, the duodenum and terminal ileum tend to be the most common site of origin. Here, we present a rare case of primary multifocal GI-FL that found incidentally during routine colonoscopy with subsequent esophagogastroduodenoscopy and video capsule endoscopy revealing duodenal, jejunal, and sigmoid colon involvement.

Double haploidentical hematopoietic stem cell transplantation results in successful engraftment of bone marrow from both donors without graft-versus-host or graft-versus-graft effects.

We established double-haploidentical (DH) hematopoietic stem cell transplantation (HSCT) murine models to explore competitive engraftment, graft-versus-graft effect and graft-versus-host disease (GVHD). T cell-depleted (TCD) bone marrow (BM) cells from B6SJF1 (donor 1 [D1]) and B6D2F1 (donor 2 [D2]) mice achieved >90% donor engraftment when transplanted into B6CBAF1 mice. B6CBAF1 recipients survived without evidence of GVHD when undergoing HSCT with TCD-BM from 2 haploidentical donors, D1 and D2. DH-HSCT recipients had significantly higher leukocyte and neutrophil counts than single-haploidentical HSCT recipients from either D1 or D2. DH recipients consistently showed successful mixed chimerism in both BM and spleen. Two other DH-HSCT models, B6D2F1 + C3D2F1→B6C3F1 and B6CBAF1 + B6SJLF1→B6D2F1, showed similar engraftment patterns. Low-dose T cell infusion from both D1 and D2 increased the degree of early engraftment of the respective donors in BM and spleen; however, this early engraftment pattern did not determine long-term engraftment dominance. In the long term, minimally engrafted D1 BM recovered and comprised >50% of all donor- derived B, T, and natural killer cells. We conclude that early BM engraftment is determined by donor T cell immunodominance, but long-term engraftment is related to the engraftment potential of stem cells after DH-HSCT.

CD30+ Lymphoproliferative Disorders as Potential Candidates for CD30-Targeted Therapies.

CONTEXT.­: In the early 1980s, a monoclonal antibody termed Ki-1 was developed against a cell line derived from a patient with Hodgkin lymphoma. This antibody detected a limited number of benign activated lymphocytes in lymphoid tissue, whereas in Hodgkin lymphoma it appeared to be nearly specific for Reed-Sternberg cells and their mononuclear variants. Subsequent studies showed that Ki-1 expression defined a new type of lymphoma that was later designated anaplastic large cell lymphoma with or without anaplastic large cell kinase expression/translocation. In the past 30 years, numerous new lymphoma entities have been defined, many of which are variably positive for CD30. Many virally transformed lymphoproliferative disorders are also frequently positive for CD30. OBJECTIVE.­: To illustrate the broad spectrum of CD30+ hematologic malignancies and to provide an update of CD30-targeted therapies. DATA SOURCES.­: Personal experiences and published works in PubMed. CONCLUSIONS.­: Because of its low expression in normal tissue, CD30 was studied as a therapeutic target for many years. However, the first functional humanized antibody against CD30 was developed only about 10 years ago. Brentuximab vedotin is a humanized anti-CD30 antibody linked to a cytotoxin, and was approved by the US Food and Drug Administration in 2012 for treating refractory Hodgkin lymphoma and anaplastic large cell lymphoma. Since then, the list of Food and Drug Administration-approved CD30-targeted hematologic malignancies has grown. Recently, the therapies using tumor antigen-specific chimeric antigen receptor T cells targeting CD30 have incited a great deal of enthusiasm and are studied in clinical trials.

Development of a novel Bruton's tyrosine kinase inhibitor that exerts anti-cancer activities potentiates response of chemotherapeutic agents in multiple myeloma stem cell-like cells.

Despite recent improvements in multiple myeloma (MM) treatment, MM remains an incurable disease and most patients experience a relapse. The major reason for myeloma recurrence is the persistent stem cell-like population. It has been demonstrated that overexpression of Bruton's tyrosine kinase (BTK) in MM stem cell-like cells is correlated with drug resistance and poor prognosis. We have developed a novel small BTK inhibitor, KS151, which is unique compared to other BTK inhibitors. Unlike ibrutinib, and the other BTK inhibitors such as acalabrutinib, orelabrutinib, and zanubrutinib that covalently bind to the C481 residue in the BTK kinase domain, KS151 can inhibit BTK activities without binding to C481. This feature of KS151 is important because C481 becomes mutated in many patients and causes drug resistance. We demonstrated that KS151 inhibits in vitro BTK kinase activities and is more potent than ibrutinib. Furthermore, by performing a semi-quantitative, sandwich-based array for 71-tyrosine kinase phosphorylation, we found that KS151 specifically inhibits BTK. Our western blotting data showed that KS151 inhibits BTK signaling pathways and is effective against bortezomib-resistant cells as well as MM stem cell-like cells. Moreover, KS151 potentiates the apoptotic response of bortezomib, lenalidomide, and panobinostat in both MM and stem cell-like cells. Interestingly, KS151 inhibits stemness markers and is efficient in inhibiting Nanog and Gli1 stemness markers even when MM cells were co-cultured with bone marrow stromal cells (BMSCs). Overall, our results show that we have developed a novel BTK inhibitor effective against the stem cell-like population, and potentiates the response of chemotherapeutic agents.

Rapidly proliferating CD44hi peripheral T cells undergo apoptosis and delay posttransplantation T-cell reconstitution after allogeneic bone marrow transplantation.

Delayed T-cell recovery is an important complication of allogeneic bone marrow transplantation (BMT). We demonstrate in murine models that donor BM-derived T cells display increased apoptosis in recipients of allogeneic BMT with or without GVHD. Although this apoptosis was associated with a loss of Bcl-2 and Bcl-X(L) expression, allogeneic recipients of donor BM deficient in Fas-, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)- or Bax-, or BM-overexpressing Bcl-2 or Akt showed no decrease in apoptosis of peripheral donor-derived T cells. CD44 expression was associated with an increased percentage of BM-derived apoptotic CD4(+) and CD8(+) T cells. Transplantation of RAG-2-eGFP-transgenic BM revealed that proliferating eGFP(lo)CD44(hi) donor BM-derived mature T cells were more likely to undergo to apoptosis than nondivided eGFP(hi)CD44(lo) recent thymic emigrants in the periphery. Finally, experiments using carboxyfluorescein succinimidyl ester-labeled T cells adoptively transferred into irradiated syngeneic hosts revealed that rapid spontaneous proliferation (as opposed to slow homeostatic proliferation) and acquisition of a CD44(hi) phenotype was associated with increased apoptosis in T cells. We conclude that apoptosis of newly generated donor-derived peripheral T cells after an allogeneic BMT contributes to delayed T-cell reconstitution and is associated with CD44 expression and rapid spontaneous proliferation by donor BM-derived T cells.

Retinoblastoma tumor suppressor gene expression determines the response to sequential flavopiridol and doxorubicin treatment in small-cell lung carcinoma.

PURPOSE: Small-cell lung cancers (SCLC) are defective in many regulatory mechanisms that control cell cycle progression, i.e., functional retinoblastoma protein (pRb). Flavopiridol inhibits proliferation and induces apoptosis in SCLC cell lines. We hypothesized that the sequence flavopiridol followed by doxorubicin would be synergistic in pRb-deficient SCLC cells. EXPERIMENTAL DESIGN: A H69 pRb-deficient SCLC cell line, H865, with functional pRb and H865 pRb small interfering RNA (siRNA) knockdown cells were used for in vitro and in vivo experiments. The in vivo efficiencies of various sequential combinations were tested using nude/nude athymic mice and human SCLC xenograft models. RESULTS: Flavopiridol then doxorubicin sequential treatment was synergistic in the pRB-negative H69 cell line. By knocking down pRb with specific siRNA, H865 clones with complete pRb knockdown became sensitive to flavopiridol and doxorubicin combinations. pRb-deficient SCLC cell lines were highly sensitive to flavopiridol-induced apoptosis. pRb-positive H865 cells arrested in G0-G1 with flavopiridol exposure, whereas doxorubicin and all flavopiridol/doxorubicin combinations caused a G2-M block. In contrast, pRb-negative SCLC cells did not arrest in G0-G1 with flavopiridol exposure. Flavopiridol treatment alone did not have an in vivo antitumor effect, but sequential flavopiridol followed by doxorubicin treatment provided tumor growth control and a survival advantage in Rb-negative xenograft models, compared with the other sequential treatments. CONCLUSIONS: Flavopiridol and doxorubicin sequential treatment induces potent in vitro and in vivo synergism in pRb-negative SCLC cells and should be clinically tested in tumors lacking functional pRB.

Long-term culture-initiating cells (LTC-IC) produced from CD34+ cord blood cells with limiting dilution method.

OBJECTIVE: Even though much progress has been made in defining primitive hematologic cell phenotypes by using flow cytometry and clonogenic methods, the direct method for study of marrow repopulating cells still remains to be elusive. Long Term Culture-Initiating Cells (LTC-IC) are known as the most primitive human hematopoietic cells detectable by in vitro functional assays. METHODS: In this study, LTC-IC with limiting dilution assay was used to evaluate repopulating potential of cord blood stem cells. RESULTS: CD34 selections from cord blood were completed succesfully with magnetic beads (73,64%±9,12). The average incidence of week 5 LTC-IC was 1: 1966 CD34+ cells (range 1261-2906). CONCLUSION: We found that number of LTC-IC obtained from CD34+ cord blood cells were relatively low in numbers when compared to previously reported bone marrow CD34+ cells. This may be due to the lack of some transcription and growth factors along with some cytokines and chemokines released by accessory cells which are necessary for proliferation of cord blood progenitor/stem cells and it presents an area of interest for further studies.

Promyelocytic Blast Crisis of Chronic Myeloid Leukemia in a Patient Undergoing Therapy with a Tyrosine Kinase Inhibitor.

A 58-year-old male with the chronic phase of chronic myeloid leukemia (CML), treated with a tyrosine kinase inhibitor (TKI), bosutinib, since the past two years, presented with bright red bleeding per rectum and disseminated intravascular coagulation. A bone marrow biopsy reverse transcription-polymerase chain reaction revealed a promyelocytic blast crisis, with leukemic cells displaying both BCR/ABL and PML/RARα chimeric genes. Cytogenetic studies revealed translocations of both t(15;17) and t(9;22). With the initiation of all-trans retinoic acid, arsenic trioxide and gemtuzumab, the patient achieved remission, with absent PML/RARα by fluorescence in situ hybridization analysis. This case highlights the importance of long-term monitoring of patients with CML, especially those on TKIs, for the development of secondary leukemias in the future.