Abstract P15: Treatment (TX) of advanced melanoma during the Coronavirus Disease 2019 (COVID-19) pandemic in Kaiser Permanente Northern California (KPNC)

The COVID-19 pandemic brought with it TX changes for many patients (pts) with AMEL, as it did for other pts with cancer. The long-term impacts of mandated area lockdowns, social distancing, medical society guidelines, and patient preference will not be fully understood for some time. The first step to learning from the pandemic is to assess how AMEL care was rendered in 2020. We performed a retrospective analysis of systemic TX for AMEL in KPNC, an integrated community healthcare system with approximately 4 million pts and about 150 de novo diagnoses of AMEL annually. We performed a chart review of pts with AMEL who were treated with standard of care systemic therapy, either immune-checkpoint inhibitors (ICI) or BRAF/MEK inhibitors (BRAF/MEKi), from January 1 to March 15, 2020, as a control group, and between March 15 and May 20, during the first wave of the COVID-19 pandemic in California with follow-up through November 4, 2020. Between January 1 and March 15, 26 pts started palliative ICI of whom 11 started combination PD1 (PD1i) and CTLA4 inhibitors. Among 15 pts who started on single-agent PD1i, 14 pts received short-interval TX (SIT), while 1 started long-interval TX (LIT). All 21 pts who started perioperative PD1i pre-pandemic, started on SIT. Between March 15 and May 20, 21 pts started palliative ICI, of whom only 3 started combination TX. Among pts who started palliative single-agent PD1i 40% started on LIT in this initial phase of the pandemic. 27 pts started perioperative ICI during this time. We found 3 started with neoadjuvant therapy and 78% started on LIT. Among 78 pts who were already on palliative single-agent ICI at the start of the COVID-19 pandemic, 15% remained on SIT and 24% changed to LIT. Sixteen pts (21%) also interrupted palliative ICI between March 15 and April 15 after a median time on TX of 45 weeks and for 63% the cited reason for interruption on chart review was the COVID 19 pandemic. Three of these pts who stopped ICI changed to BRAF/MEKi, the remainder continue in active follow-up as of November 2020. Among 72 pts already receiving perioperative ICI in March 2020, 19% remained on SIT, 35% changed to LIT, and 11% were already on LIT. 39% of pts interrupted perioperative ICI after a median time of 20 weeks on TX and 46% of these cited COVID 19 as the reason for interruption. Three pts have since resumed peri-operative TX, but the others remain in active follow-up off therapy. Between 3/15 and 5/30/2020, we noted a 325% increase in pts started on BRAF/MEKi; 69% of pts received therapy for palliative intent. The start of the COVID-19 pandemic saw many different changes in AMEL TX in KPNC, with increased use of single-agent ICI, LIT, and oral therapy, in line with public health guidance, oncology societal guidelines and patient preference. It will be important to assess the long-term outcomes relating to these changes, including the impact of early discontinuation of ICI, to help guide future Melanoma care during and after the pandemic.

Citation Format: Juraj Kavecansky, Nina Shah, Angeles Price, Frank Hsieh, Alice Kengla, Belinda Ark, Jahan Tavakoli, Christine Kaiser, Mingqing Li, Sejal Jhatakia, Mala Reddy, Dazhi Cen, Philip Sardar, Stephen Wang, Ashok Pai, Andrea Harzstark, Tatjana Kolevska, Thach-Giao Truong. Treatment (TX) of advanced melanoma during the Coronavirus Disease 2019 (COVID-19) pandemic in Kaiser Permanente Northern California (KPNC) [abstract]. In: Proceedings of the AACR Virtual Meeting: COVID-19 and Cancer; 2021 Feb 3-5. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(6_Suppl):Abstract nr P15.

Atypical manifestations of coronavirus disease 2019 (COVID-19)-associated autoimmune thrombotic thrombocytopenic purpura

Patients with coronavirus disease 2019 (COVID-19) infection can have various abnormal hematologic parameters. This report illustrates a case with unusual presentation of COVID-19-associated thrombotic thrombocytopenic purpura, in which the patient did not develop any typical respiratory signs or symptoms.

[Severe acute pancreatitis with iatrogenic duodenal fistula: cause and minimal invasive treatment]

Objective: To investigate the causes and treatment of severe acute pancreatitis (SAP) with iatrogenic duodenal fistula. Methods: The clinical data of the SAP patients with duodenal fistula treated in the Severe Acute Pancreatitis Center of Sir Run Run Shaw Hospital from May 2015 to May 2018 was analyzed retrospectively. Results: A total of 11 patients were enrolled, among which 5 cases of duodenal fistula were caused by iatrogenic injury, including 2 cases of puncture injury, 2 cases of nutritional tube injury and 1 case of drainage tube injury. For patients with poor infection control after conservative treatment, laparoscopic assisted debridement through the right retroperitoneal approach was performed. Treatment of two patients failed for liver failure and the remaining patients were cured. Conclusions: Iatrogenic injury is one of the causes of duodenal fistula in patients with severe pancreatitis. Laparoscopic assisted debridement through the right retroperitoneal approach is an effective treatment for duodenal fistula.

Disulfiram Facilitates Intracellular Cu Uptake and Induces Apoptosis in Human Melanoma Cells

The alcohol-abuse deterrent disulfiram (DSF) is shown to have a highly selective toxicity against melanoma in culture, inducing a largely apoptotic response, with much lower toxicity against several other cell lines. Melanoma cell lines derived from different stages (radial, vertical, and metastatic phase) were all sensitive to DSF treatment in vitro; melanocytes were only slightly affected. A required role of extracellular Cu is demonstrated for DSF toxicity. Low concentrations of DSF alone decreased the number of viable cells, and the addition of CuCl(2) significantly enhanced the DSF-induced cell death to less than 10% of control. Significantly, the intracellular Cu concentration of melanoma cells increased rapidly upon DSF treatment. Both the intracellular Cu uptake and the toxicity induced by DSF were blocked by co-incubation with bathocuproine disulfonic acid (BCPD, 100 muM), a non-membrane-permeable Cu chelator. Chemical studies demonstrated a complicated, extracellular redox reaction between Cu(II) and DSF, which forms the complex Cu(deDTC)(2) in high yield, accompanied by oxidative decomposition of small amounts of disulfiram. The Cu complex has somewhat higher activity against melanoma and is suggested to be the active agent in DSF-induced toxicity. The redox conversion of DSF was unique to Cu(II) and not engendered by the other common biological metal ions Fe(II or III), Mn(III), and Zn(II). The implications of this work are significant both in the possible treatment of melanoma as well as in limiting the known side-effects of DSF, which we propose may be diminished by cotreatment to decrease adventitious Cu.

Comparative expression of NFkappaB proteins in melanocytes of normal skin vs. benign intradermal naevus and human metastatic melanoma biopsies

Nuclear factor kappa B (NFkappaB) is an essential regulator of gene transcription for hundreds of genes, including many critically involved in apoptosis. NFkappaB complexes containing cRel generally activate pro-apoptotic genes, while those with RelA activate anti-apoptotic genes. We have previously shown that NFkappaB binding by RelA is constitutively elevated in human metastatic melanoma cultures relative to normal melanocytes. Here we extended our investigation to immunohistochemical analysis of human tissue biopsies. We found that RelA expression is significantly elevated in melanocytes of human naevi and melanomas relative to normal skin, but expression of its inhibitor IkappaB-alpha is significantly lower in metastatic melanomas than in intradermal naevi. Antibodies specific for the nuclear localization signal of RelA also showed significantly increased staining in metastatic melanoma biopsies. Notably, in melanomas and in naevi, we also found that RelA is phosphorylated at serine 529, and this activated form accumulates in the nuclei of melanomas. This suggests that increased expression and phosphorylation of RelA occurs at the stage of the benign naevus, but IkappaB-alpha is able to sequester RelA in the cytoplasm and regulate RelA transcriptional transactivation. We also found that antibodies against cRel show a progressive increase in staining from naevi to melanoma. However, staining for IkappaB-epsilon, which primarily inhibits the nuclear localization of cRel was also progressively increased, and cRel expression was predominantly cytoplasmic in melanomas. These results confirm that the altered expression of RelA found in metastatic melanoma cells in tissue culture is relevant to human tumors and offer new insights into the deregulation of NFkappaB signaling.

Disulfiram induces apoptosis in human melanoma cells: a redox-related process

Melanoma is highly resistant to conventional chemotherapy. We have demonstrated that redox regulation in melanoma cells is aberrant, and redox-modulating agents can induce cell apoptosis. We have currently explored the effect of disulfiram (DSF), a member of the dithiocarbamate family, on apoptosis of melanoma cells in vitro. Human metastatic melanoma cells c81-46A, c81-61, and c83-2C were treated with DSF and apoptosis measured. DSF, at a dose of 25-50 ng/ml, consistently caused a 4-6-fold increase in apoptosis. The same dose of DSF did not significantly affect apoptosis in melanocytes. Coincubation of N-acetyl-cysteine reversed the DSF-induced apoptosis. Buthionine sulfoximine (BSO), an inhibitor of gamma-glutamyl-cysteine synthetase, as a single agent caused a approximately 2-fold increase in apoptosis when incubated with melanoma cells for 4 days. BSO slightly enhanced the level of apoptosis induced by DSF (4-10% higher than DSF alone). Intracellular glutathione was remarkably depleted with BSO treatment. DSF did not cause glutathione depletion; however, the ratio of reduced and oxidized glutathione was significantly decreased (14% of control), and N-acetyl-cysteine partially restored the ratio to 30% of control. There was a transient (2-fold) elevation of intracellular superoxide level after 24 h of DSF treatment (before the overt apoptosis). The intracellular H2O2 level progressively decreased with time. DSF decreased the mitochondrial membrane polarization in a time-dependent manner, and there was a significant inverse correlation between apoptosis and mitochondrial membrane polarization. We propose that DSF-induced apoptosis is redox related but involves a different mechanism from BSO-induced apoptosis in tumor cells. Our findings have provided new data for additional understanding of drug-induced apoptosis in melanoma cells and suggests an alternative therapeutic approach to melanoma.

Human T, B, natural killer, and dendritic cells arise from a common bone marrow progenitor cell subset

The early stages of lymphoid cell formation were studied by testing the differentiative potential of phenotypically defined subsets of CD34+ bone marrow cells. A subpopulation of CD34+ Lin- CD45RA+ cells expressing CD10 was isolated by flow cytometry. Such cells are CD38+, HLA-DR+, do not express significant levels of Thy-1 and c-kit, lack erythroid, myeloid, megakaryocytic potential, and give rise only to lymphoid T, B, natural killer (NK), and dendritic cells (DC) in kinetics and titration experiments. Limiting dilution analysis demonstrates the existence of multipotential B/NK/DC progenitor clones in the CD34hi Lin-CD10+ adult bone marrow cell population. Thus, nonprimitive progenitors for lymphoid cells and for DCs can be distinct from those of myeloid, megakaryocytic, and erythroid cells, implying that the DC lineage is developmentally more closely related to the lymphoid lineage than to the myeloid lineage. This study provides new insights into the organization and development of the human lympho-hematopoietic system.

Delineation of T-progenitor cell activity within the CD34+ compartment of adult bone marrow

T-cell production is largely dependent on the presence of a thymus gland where CD34+ precursors mature into T lymphocytes. Prethymic stages of T-cell development are less defined. Therefore, this study aims to delineate T-progenitor cell potential within the CD34+ Lineage--(Lin-) cell compartment of adult bone marrow (ABM). Fractionation of CD34+ Lin- ABM cells with CD45RA, Thy-1, CD38, and HLA-DR failed to absolutely segregate T-cell reconstituting ability, indicating broad distribution of T-progenitor cell potential. Titration experiments showed that low numbers of CD34+ Lin- CD45RA+ (RA+) cells had greater thymus repopulating ability than CD34+ Lin- CD45RA- cells (RA-). The great majority (> 95%) of RA+ cells expressed CD38, HLA-DR and 70% to 90% of RA+ cells lacked Thy-1 surface expression. RA+ cells contained colony-forming unit granulocyte-macrophage (CFU-GM) progenitor cells but were depleted of erythroid potential, did not provide hematopoietic reconstitution of human bone fragments implanted into SCID mice, and did not efficiently maintain CD34+ cells with secondary clonogenic potential in bone marrow cultures. Thus, RA+ cells are oligopotent (nonprimitive) CD34+ progenitors with T-cell reconstituting ability. In contrast, these same assays indicated that CD34+ Lin- CD45RA- cells (RA- cells) comprised hematopoietic stem cells (HSC) with primitive multilineage (T, B, myeloid, and erythroid) hematopoietic potential. It was confirmed that HSC-containing populations, such as CD34+ Lin- CD45RA- Thy-1+ cells had thymus repopulating ability. Culture of RA- cells on murine bone marrow stromal cells in the presence of interleukin (IL)-3, IL-6, and leukemia inhibitory factor (LIF) generated CD34+ CD45RA+ progeny engrafting in a secondary severe combined immunodeficiency (SCID)-hu thymus assay. Altogether, our results underscore the fact that T-cell reconstituting potential can be dissociated from HSC activity. Furthermore, we speculate that HSC might develop into the T lineage indirectly, via differentiation into an intermediate oligopotent CD34+ CD45RA+ stage. Finally, T-progenitor cells can be cultured in vitro.

Generation of T cells from cytokine-mobilized peripheral blood and adult bone marrow CD34+ cells

The present study compared the T-cell progenitor content of CD34+ lineage (Lin)- cells isolated from normal adult bone marrow (ABM) and mobilized peripheral blood (MPB). Both cell populations were found to differentiate into T cells when injected into human fetal thymi implanted into severe combined immunodeficient mice. Cytokine-MPB cells were less efficient than ABM cells in engrafting in the fetal human thymus, although both gave rise to thymocytes with identical phenotypes based on the analysis of CD1a, CD3, CD4, and CD8 expression. Thymocytes derived from adult CD34+ Lin- cells were capable of fully differentiating into mature CD3+ T cells expressing either the T-cell receptor (TCR) gamma delta or the TCR alpha beta (the later associated with CD4 or CD8), showing that the T-cell progenies of adult CD34+ cells were polyclonal and functional. Our data indicate that human MPB CD34+ cells are qualitatively identical to their BM counterparts, and demonstrate the existence of T-lymphoid progenitor cell activity in MPB.

Transcriptional regulation and chromatin structure of the human CD34 gene promoter region

The human CD34 surface antigen is selectively expressed on stem/progenitor cells within the hematopoietic system. Because CD34 expression is tightly linked to the immature status of hematopoietic cells, with expression being rapidly lost as hematopoietic cells mature and differentiate, an examination of its regulation may provide important insights into the molecular control of blood cell development. A comparison of the CD34 nuclear transcription rate in CD34+ and CD34- cells indicated that the CD34 gene is transcriptionally regulated in hematopoietic cell lines. In a previous report, we had identified two major clusters of CD34 transcription initiation sites by 5' RACE (rapid amplification of cDNA ends) analysis. In transient transfection experiments, we now demonstrate the ability of sequences encompassing each of these clusters to function as promoters of transcription in CD34+ cells. These promoters functioned at equivalent levels in CD34+ and CD34- cells, and the addition of 5' flanking sequences, extending as far as 3.7 kb upstream, to the core promoters did not differentially modify the level of expression in CD34+ versus the CD34- cell lines. An examination of DNase I hypersensitivity sites within an 18-kb segment of DNA, extending 9 kb either side of the proximal promoter, showed six sites that were primarily associated with CD34- expressing cells. Taken together, these data indicate that the CD34 promoter sequences alone do not confer tissue-or stage-specific expression. Appropriate transcriptional regulation of the CD34 gene must be controlled by chromatin structure, as identified by DNase I hypersensitivity, and/or by other tissue- and stage-specific elements present outside of the promoter region.

Effect of different human immunodeficiency virus type-1 (HIV-1) isolates on long-term bone marrow haemopoiesis

Haemopoietic cytopenias are a frequent occurrence in human immunodeficiency virus type-1 (HIV-1) induced disease. In order to examine the possible direct inhibition of marrow haemopoiesis by HIV-1, we have investigated the effect of HIV-1 infection on myelopoiesis in long-term bone marrow cultures. In vitro exposure of normal marrow cultures to three different lymphocytotropic HIV-1 isolates resulted in productive infection, as demonstrated by a progressive increase of gag p24 antigen. In these experiments, ICR-3 isolate, but not LAV' or NL4-3 isolates, accelerated the loss of non-adherent cells. A differential ability of these HIV-1 isolates to suppress myelopoiesis was confirmed in long-term cultures in which virus was added continuously. In these cultures, ICR-3, and to a lesser extent also NL4-3, but not LAV', induced a progressive decrease in the number of total non-adherent cells as well as non-adherent colony forming units-granulocyte/macrophage (CFU-GM). Furthermore, exposure of normal purified CD34+ cells to ICR-3 induced defects in their ability to form haemopoietic colonies; this inhibitory effect was significantly relieved by pretreatment of ICR-3 with an anti-gp120 antibody. Similar exposure of CD34+ cells to LAV' and NL4-3 induced no such defects. These data indicate that some HIV-1 isolates can impair bone marrow haemopoiesis in a dose-dependent fashion, acting, at least in part, at the level of haemopoietic stem/progenitor cells.

Cell cycle status of murine megakaryocyte and granulocyte-macrophage colony-forming cells in bone marrow and spleen

The cell cycle status of megakaryocyte colony-forming cells (Meg-CFC) and granulocyte-macrophage colony-forming cells (GM-CFC) from the spleen and bone marrow of C57BL mice was evaluated by determining the effects of hydroxyurea (OHU) or cytosine arabinoside (Ara-C), both in vivo and in vitro, upon colony-forming cells (CFC). The concentrations of cells in culture (2 x 10(6) to 4 x 10(6)/ml for spleen and 0.25 x 10(5) to 1.0 x 10(5)/ml for bone marrow) did not alter cell cycle status of either Meg-CFC or GM-CFC. Determination of cell cycle status following in vivo administration of OHU indicated that 25.2% of Meg-CFC and 28.1% of GM-CFC in the spleen, and 26.0% of Meg-CFC and 29.5% of GM-CFC in the bone marrow, were in cycle. In vitro incubation of CFC with OHU showed that in the spleen 25.1% of Meg-CFC and 24.2% of GM-CFC were engaged in DNA synthesis, whereas in bone marrow 28.5% of Meg-CFC and 29.2% of GM-CFC were synthesizing DNA. Incubation with Ara-C, in vitro, gave similar results, with 26.0% of Meg-CFC and 26.2% of GM-CFC in the spleen, and 27.1% of Meg-CFC and 31.4% of GM-CFC in the bone marrow, in cycle. In summary, significant differences were not observed between the cell cycle status of Meg-CFC and GM-CFC, whether derived from spleen or bone marrow. In vitro and in vivo measurements (with OHU) and in vitro measurements with two cytotoxic drugs (OHU versus Ara-C) also provided similar results. The data suggest that the regulation of DNA synthesis in both Meg-CFC and GM-CFC in the murine spleen and bone marrow is similar.