Prolonged Lenalidomide Induction Does Not Significantly Impair Stem Cell Collection in Multiple Myeloma Patients Mobilized With Cyclophosphamide or Plerixafor: A Report From The Covid Era.

INTRODUCTION: Induction therapy for multiple myeloma is traditionally capped at 6 cycles of lenalidomide due to concerns that longer treatment compromises the ability to collect sufficient stem cells for autologous stem cell transplantation (ASCT). However, during the COVID-19 pandemic, many of our patients received prolonged lenalidomide induction due to concerns about proceeding to ASCT. We investigated whether prolonged induction with lenalidomide affects the efficacy of stem cell collection among patients mobilized with cyclophosphamide and/or plerixafor. PATIENTS AND METHODS: This single center, retrospective study included patients who were treated with lenalidomide induction regimens, received mobilization with cyclophosphamide or plerixafor, and underwent apheresis in preparation for ASCT. 94 patients were included, 40 of whom received prolonged induction with >6 cycles of lenalidomide containing regimen. RESULTS: Patients who received prolonged induction were more likely to require >1 day of apheresis (38% vs. 15%; OR 3.45; P = .0154), and there was a significant correlation between the duration of lenalidomide treatment and the apheresis time required to collect sufficient cells for transplant (R2 = 0.06423, P = .0148). However, there was no significant difference between patients who received prolonged induction and those who did not with respect to CD34+ stem cell yields at completion of apheresis (9.99 vs. 10.46 cells/Kg, P = .5513) or on the first day of collection (8.29 vs. 9.59 cells/Kg, P = .1788). CONCLUSION: Among patients treated with >6 cycles of lenalidomide, mobilization augmented with cyclophosphamide and/or plerixafor will likely facilitate sufficient stem cell harvest to permit ASCT.

Cancer stem cells, not bulk tumor cells, determine mechanisms of resistance to SMO inhibitors.

The emergence of treatment resistance significantly reduces the clinical utility of many effective targeted therapies. Although both genetic and epigenetic mechanisms of drug resistance have been reported, whether these mechanisms are stochastically selected in individual tumors or governed by a predictable underlying principle is unknown. Here, we report that the dependence of cancer stem cells (CSCs), not bulk tumor cells, on the targeted pathway determines the molecular mechanism of resistance in individual tumors. Using both spontaneous and transplantable mouse models of sonic hedgehog (SHH) medulloblastoma (MB) treated with an SHH/Smoothened inhibitor, sonidegib/LDE225, we show that genetic-based resistance occurs only in tumors that contain SHH-dependent CSCs (SD-CSCs). In contrast, SHH MBs containing SHH-dependent bulk tumor cells but SHH-independent CSCs (SI-CSCs) acquire resistance through epigenetic reprogramming. Mechanistically, elevated proteasome activity in SMOi-resistant SI-CSC MBs alters the tumor cell maturation trajectory through enhanced degradation of specific epigenetic regulators, including histone acetylation machinery components, resulting in global reductions in H3K9Ac, H3K14Ac, H3K56Ac, H4K5Ac, and H4K8Ac marks and gene expression changes. These results provide new insights into how selective pressure on distinct tumor cell populations contributes to different mechanisms of resistance to targeted therapies. This insight provides a new conceptual framework to understand responses and resistance to SMOis and other targeted therapies.

Hepatic AL Amyloidosis without Significant Light Chain Elevation in a Patient Treated with CyBorD Plus Daratumumab.

BACKGROUND Immunoglobulin light chain (AL) amyloidosis is a plasma cell disorder in which excess light chain deposits in tissues, resulting in organ dysfunction and damage. Typically, AL amyloidosis presents as a systemic disease affecting multiple organs, and most patients have elevated serum free light chains. However, the presentation of AL amyloidosis is highly variable. The purpose of this case report is to raise awareness of the atypical presentations of AL amyloidosis in order to facilitate more rapid diagnosis, which has the potential to prevent additional organ damage when appropriate therapy is provided. CASE REPORT We describe a case of AL amyloidosis with amyloid deposition confined to the liver and bone marrow and lack of significant serum light chain elevation. The patient initially presented with a spontaneous hepatic hematoma, and was ultimately found to have hepatic AL amyloidosis, with monoclonal plasma cells in the bone marrow and monoclonal protein on serum protein electrophoresis. Our patient responded to treatment with cyclophosphamide-bortezomib-dexamethasone, the anti-CD38 antibody daratumumab, and autologous stem cell transplant, resulting in hematological and organ response. CONCLUSIONS AL amyloidosis can present with end-organ damage confined to isolated organs, and it can present without the expected elevation in serum light chains. Such patients can benefit from appropriate treatment, including traditional chemotherapy, daratumumab, and stem cell transplant. As effective treatments for AL amyloidosis are now available, prompt diagnosis has the potential to limit end-organ damage and potentially improve patient outcomes.

Preclinical Metrics Correlate With Drug Activity in Phase II Trials of Targeted Therapies for Non-Small Cell Lung Cancer.

Novel oncology drugs often fail to progress from preclinical experiments to FDA approval. Therefore, determining which preclinical or clinical factors associate with drug activity could accelerate development of effective therapies. We investigated whether preclinical metrics and patient characteristics are associated with objective response rate (ORR) in phase II clinical trials of targeted therapies for non-small cell lung cancer (NSCLC). We developed a reproducible process to select a single phase II trial and supporting preclinical publication for a given drug-indication pair, which we defined as the pairing of a small molecule inhibitor (e.g., crizotinib) with the specific patient population for which it was designed to work (e.g., patients with an ALK aberration). We demonstrated that robust drug activity in mice, as measured by change in tumor size, is independently associated with improved ORR in phase II clinical trials. The number of mice utilized in experiments, the number of publications referencing the drug for NSCLC before the phase II clinical trial, and whether the drug was approved for a cancer other than NSCLC also significantly correlated with ORR. Among clinical characteristics, sex, race, histology, and smoking history were significantly associated with ORR. Further research into metrics that correlate with drug activity has the potential to optimize selection of novel therapies for clinical trials and enrich the drug development pipeline, particularly for patients with targetable genetic aberrations and rare cancers.

An 8-Year-Old Boy With Fever, Splenomegaly, and Pancytopenia.

An 8-year-old boy with no significant past medical history presented to his pediatrician with 5 days of fever, diffuse abdominal pain, and pallor. The pediatrician referred the patient to the emergency department (ED), out of concern for possible malignancy. Initial vital signs indicated fever, tachypnea, and tachycardia. Physical examination was significant for marked abdominal distension, hepatosplenomegaly, and abdominal tenderness in the right upper and lower quadrants. Initial laboratory studies were notable for pancytopenia as well as an elevated erythrocyte sedimentation rate and C-reactive protein. Computed tomography (CT) of the abdomen and pelvis showed massive splenomegaly. The only significant history of travel was immigration from Albania 10 months before admission. The patient was admitted to a tertiary care children's hospital and was evaluated by hematology-oncology, infectious disease, genetics, and rheumatology subspecialty teams. Our multidisciplinary panel of experts will discuss the evaluation of pancytopenia with apparent multiorgan involvement and the diagnosis and appropriate management of a rare disease.

Multifocal primary neuroblastoma tumor heterogeneity in siblings with co-occurring PHOX2B and NF1 genetic aberrations.

Neuroblastoma, the most common extracranial solid tumor of childhood, can present in multiple primary sites, but the extent of genetic heterogeneity among tumor foci, as well as the presence or absence of common oncogenic drivers, remains unknown. Although PHOX2B genetic aberrations can cause familial neuroblastoma, they demonstrate incomplete penetrance with respect to neuroblastoma pathogenesis, suggesting that additional undescribed oncogenic drivers are necessary for tumor development. We performed comprehensive molecular characterization of neuroblastoma tumors from two siblings affected by familial multifocal neuroblastoma, including whole exome sequencing and single-nucleotide polymorphism (SNP) arrays of tumor and matched blood samples. Data were processed and analyzed using established bioinformatics algorithms to evaluate for germline and somatic mutations and copy number variations (CNVs). We confirmed the presence of a PHOX2B deletion and NF1 mutation across all tumor samples and the germline genome. Matched tumor-blood whole exome sequencing also identified 365 genes that contained nonsilent coding mutations across all tumor samples, with no recurrent mutations across all tumors. SNP arrays also showed significant heterogeneity with respect to CNVs. The only common CNV across all tumors was 17q gain, with differing chromosomal coordinates across samples but a common region of overlap distal to 17q21.31, suggesting this adverse prognostic biomarker may offer insight about additional drivers for multifocal neuroblastoma in patients with germline PHOX2B or NF1 aberrations. Molecular characterization of all tumors from patients with multifocal primary neuroblastoma has potential to yield novel insights on neuroblastoma pathogenesis.

Systemic manifestations of extraskeletal myxoid chondrosarcoma associated with a novel t(2;22)(q34;q12) EWS translocation in a child and a review of the literature.

Extraskeletal myxoid chondrosarcoma (EMC), a soft-tissue sarcoma with unique clinicopathologic features and characteristic chromosomal translocations, is extremely rare in the pediatric population. We, herein, present the case of a 7-year-old boy with profound microcytic hypochromic anemia, poor weight gain and a mid-thoracic paraspinal mass that was identified as EMC. Systemic manifestations of localized, nonmetastatic EMC have never been described in the pediatric population, yet our patient's anemia and poor weight gain resolved after successful surgical resection of the tumor, suggesting that localized EMC can present with systemic manifestations. The tumor also contained a novel t(2;22)(q34;q12) translocation involving the EWSR1 gene, which is consistent with additional reports suggesting that a growing list of translocations can drive formation of, and potential new management strategies for, EMC.

Addressing intra-tumoral heterogeneity and therapy resistance.

In the last several years, our appreciation of intra-tumoral heterogeneity has greatly increased due to accumulating evidence for the co-existence of genetically and epigenetically divergent cancer cells residing in different microenvironments within a tumor. Herein, we review recent literature discussing intra-tumoral heterogeneity in the context of therapy resistance mechanisms at the genetic, epigenetic and microenvironmental levels. We illustrate the influence of tumor microenvironment on therapy resistance and epigenetic states of cancer cells by highlighting the role of cancer stem cells in therapy resistance. We also summarize different strategies that have been employed to address various resistance mechanisms at genetic, epigenetic, and microenvironmental levels in preclinical and clinical studies. We propose that future personalized cancer therapy design needs to incorporate dynamic and comprehensive analyses of tumor heterogeneity landscape and multi-dimensional mechanisms of therapy resistance.

Epigenetic states of cells of origin and tumor evolution drive tumor-initiating cell phenotype and tumor heterogeneity.

A central confounding factor in the development of targeted therapies is tumor cell heterogeneity, particularly in tumor-initiating cells (TIC), within clinically identical tumors. Here, we show how activation of the Sonic Hedgehog (SHH) pathway in neural stem and progenitor cells creates a foundation for tumor cell evolution to heterogeneous states that are histologically indistinguishable but molecularly distinct. In spontaneous medulloblastomas that arise in Patched (Ptch)(+/-) mice, we identified three distinct tumor subtypes. Through cell type-specific activation of the SHH pathway in vivo, we determined that different cells of origin evolved in unique ways to generate these subtypes. Moreover, TICs in each subtype had distinct molecular and cellular phenotypes. At the bulk tumor level, the three tumor subtypes could be distinguished by a 465-gene signature and by differential activation levels of the ERK and AKT pathways. Notably, TICs from different subtypes were differentially sensitive to SHH or AKT pathway inhibitors, highlighting new mechanisms of resistance to targeted therapies. In summary, our results show how evolutionary processes act on distinct cells of origin to contribute to tumoral heterogeneity, at both bulk tumor and TIC levels.

The wound healing, chronic fibrosis, and cancer progression triad.

For decades tumors have been recognized as "wounds that do not heal." Besides the commonalities that tumors and wounded tissues share, the process of wound healing also portrays similar characteristics with chronic fibrosis. In this review, we suggest a tight interrelationship, which is governed as a concurrence of cellular and microenvironmental reactivity among wound healing, chronic fibrosis, and cancer development/progression (i.e., the WHFC triad). It is clear that the same cell types, as well as soluble and matrix elements that drive wound healing (including regeneration) via distinct signaling pathways, also fuel chronic fibrosis and tumor progression. Hence, here we review the relationship between fibrosis and cancer through the lens of wound healing.