History of Acute Promyelocytic Leukemia: A Tale of Endless Revolution

Only few thousand people are diagnosed each year of Acute Promyelocytic Leukemia (APL) worldwide. However, for a number of reasons such rare disease is regarded as a paradigm in the entire field of medicine. Once considered the most malignant human leukemia as well as the one associated with the worst prognosis, APL has been transformed in the past few decades into the most frequently curable one. This extraordinary progress has been the result of an unprecedented coincidence of advances in both biological and clinical research

Vitamin C Against Cancer

The selective anticancer properties of vitamin C are known since at least four decades. However, only recently in vitro studies have shown that vitamin C, in high enough concentrations, can efficiently and selectively kill a number of different human tumor cell lines, and these data have been confirmed in experimental animal tumor models. The first human clinical trials revealed that high doses of vitamin C administered by intravenous injection are not only very well tolerated but also substantially improve the quality of life of patients with clinically advanced cancer. However, the clinical evidence of the effectiveness of vitamin C in fighting off cancer is still controversial. The present chapter outlines the importance of vitamin C for a number of physiological functions, within the human body, and shows that there is a solid rationale for its use in the routine treatment of cancer, either alone or in combination with conventional treatment

Retinoic acid-induced differentiation sensitizes myeloid progenitors cells to ER stress

The clonal expansion of hematopoietic myeloid precursors blocked at different stages of differentiation characterizes the acute myeloid leukemia (AML) phenotype. A subtype of AML, acute promyelocytic leukemia (APL), characterized by the chimeric protein PML-RARα is considered a paradigm of differentiation therapy. In this leukemia subtype the all-trans-retinoic acid (RA)-based treatments are able to induce PML-RARα degradation and leukemic blast terminal differentiation [1-2]. Granulocytic differentiation of APL cells driven by RA triggers a physiological Unfolded Protein Response (UPR), a series of pathways emanating from the ER in case of ER stress, which ensues when higher protein folding activity is required as during differentiation. We show here that, although mild, the ER stress induced by RA is sufficient to render human APL cell lines and primary blasts very sensitive to low doses of Tunicamycin (Tm), an ER stress inducing drug, at doses that are not toxic in the absence of RA. Importantly only human progenitors cells derived from APL patients resulted sensitive to the combined treatment with RA and Tm whereas those obtained from healthy donors were not affected. We also show that the UPR pathway downstream of PERK plays a major protective role against ER stress in differentiating cells and, by using a specific PERK inhibitor, we potentiated the toxic effect of the combination of RA and Tm. In conclusion, our findings identify the ER stress-related pathways as potential targets in the search for novel therapeutic strategies in AML

The cure from nature: the extraordinary anticancer properties of Ascorbate (Vitamin C)

The anticancer properties of Vitamin C (ascorbic acid o sodium ascorbate) are known since at least four decades, However, being a cheap and "natural" product, Vitamin C is not patentable and therefore has never been developed as an anticancer molecule. Recent in vitro investigations have confirmed the extraordinary antitumor properties of high doses of Vitamin C (sodium ascorbate), particularly when administered by the intravenous route, and phase I/II randomized, controlled clinical trials have been started to verify its anticancer properties in vivo. Unfortunately, the controlled clinical trials performed so far, do not confirm the extraordinary results obtained with Vitamin C (sodium ascorbate) in vitro. However, this may depend on a number of different factors, such as the pharmaceutical preparation (Sodium ascorbate may be more suitable than buffered ascorbic acid), the schedule of administration (slow infusion better than rapid infusion), tumor tissue oxygenation (Cancer tissue oxygenation is lower that oxygenation of tumor cell lines, in vitro), etc., which deserve further in depth investigation. Even with these limitations, Vitamin C (sodium ascorbate) in high doses, administered by intravenous route, beyond being extremely effective in vitro, against a number of human tumor cell lines, is safe, has minimal contraindications, improves the quality of life of patients, and is highly selective for cancer cells. The Authors discuss these important aspects and suggest possible solutions to improve the in vivo anticancer effects of Vitamin C (sodium ascorbate)

High Doses of Vitamin C and Leukemia: In Vitro Update

Vitamin C (ascorbic acid) is an essential nutrient with a number of beneficial effects on the human body. Although the majority of mammals can synthesize their own Vitamin C, humans and a few other species, do not produce it and depend on dietary sources for their Vitamin C supply. Among its many effects on cell function and metabolism, Vitamin C has shown, in vitro, a powerful anticancer effect against a number of human tumor cell lines, including myeloid leukemia. There are many different mechanistic explanations for the anticancer/anti-leukemic effects of Vitamin C and the aim of the present review is to illustrate these mechanisms, showing the results of some preliminary in vitro investigations, and outlining their potential clinical relevance

Sustained molecular remission after low dose gemtuzumab-ozogamicin in elderly patients with advanced acute promyelocytic leukemia.

We report here a preliminary experience with gemtuzumab ozogamicin (GO) used at low dosage (3 mg/m2) in 3 elderly patients with acute promyelocytic leukaemia (APL) who presented molecular relapse and were unfit for intensive chemotherapy

Promyelocytic Sarcoma of the Spine: A Case Report and Review of the Literature

Myeloid sarcoma (MS, previously named granulocytic sarcoma or chloroma) is a rare extramedullary tumour of immature myeloid cells. It can be present before, concurrently with, or after the diagnosis of acute myeloid leukemia. MS is extremely uncommon in acute promyelocytic leukemia (APL). In the case described here, MS was the sole site of APL relapse and the cause of spinal cord compression. The patient presented with neurologic symptoms due to a paravertebral mass of MS after 7 years of complete remission. He was treated with excision of the mass followed by local radiotherapy. Systemic treatment was also given with combined arsenic trioxide and all-trans retinoic acid and the patient was able to achieve a second prolonged clinical and molecular remission

Retinoic acid sensitizes acute myeloid leukemia cells to ER stress

Acute myeloid leukemia (AML) is caused by the blockade of hematopoietic myeloid precursors at different stages of differentiation. A subtype of AML, acute promyelocytic leukemia (APL), is a paradigm of differentiation therapy since retinoic acid (RA) is able to induce leukemic blast terminal differentiation leading to cure rates exceeding 80% when administered in combination with chemotherapy. Although APL patients refractory to RA or who relapsed are very effectively treated with arsenic trioxide (ATO) in combination with RA, the elevated costs limit its use in developing countries and in first line therapy so that RA plus chemotherapy currently remain the standard of care (1, 2). Most importantly non-APL acute myeloid leukemia do not respond to RA indicating the need for novel strategies to sensitize AML cells to RA. Here we show that RA-triggered differentiation of APL cells induces endoplasmic reticulum (ER) stress slightly activating the unfolded protein response (UPR). This is sufficient to render leukemic cell lines and human primary blasts very sensitive to doses of ER stress inducing drugs, like tunicamycin (Tm), that are not toxic for the same cells in the absence of RA or for most cell types. Furthermore we observed that low doses of Tm, even in the absence of RA, are sufficient to strongly increase ATO toxicity. Indeed both RA-sensitive and RA-resistant APL cell lines resulted sensitive to Tm-ATO combined treatment at low doses of ATO that are ineffective in the absence of ER stress. The use of inhibitors targeting specific UPR branches indicate that the Protein Kinase RNA-like Endoplasmic Reticulum kinase (PERK) pathway protects differentiating APL cells from ER stress rendering it an interesting therapeutic molecular target. Finally, we extended our observations in a non-APL model, assessing that RA sensitize the non-APL cell line HL60 to ER stress. Altogether our data indicate ER stress as a possible target for designing novel combination therapeutic strategies in AML. Contribution of AIRC (StG 4841) and FILAS-RU-2014-1020 to FF was greatly appreciated

Retinoic Acid-induced differentiation sensitizes myeloid progenitors cells to ER stress

The clonal expansion of hematopoietic myeloid precursors blocked at different stages of differentiation characterizes the acute myeloid leukemia (AML) phenotype. A subtype of AML, acute promyelocytic leukemia (APL), characterized by the chimeric protein PML-RARα is considered a paradigm of differentiation therapy. In this leukemia subtype the all-trans-retinoic acid (RA)-based treatments are able to induce PML-RARα degradation and leukemic blast terminal differentiation [1-2]. Granulocytic differentiation of APL cells driven by RA triggers a physiological Unfolded Protein Response (UPR), a series of pathways emanating from the ER in case of ER stress, which ensues when higher protein folding activity is required as during differentiation. We show here that, although mild, the ER stress induced by RA is sufficient to render human APL cell lines and primary blasts very sensitive to low doses of Tunicamycin (Tm), an ER stress inducing drug, at doses that are not toxic in the absence of RA. Importantly only human progenitors cells derived from APL patients resulted sensitive to the combined treatment with RA and Tm whereas those obtained from healthy donors were not affected. We also show that the UPR pathway downstream of PERK plays a major protective role against ER stress in differentiating cells and, by using a specific PERK inhibitor, we potentiated the toxic effect of the combination of RA and Tm. In conclusion, our findings identify the ER stress-related pathways as potential targets in the search for novel therapeutic strategies in AML

Deferral of assessment of pulmonary embolism

We evaluated a simplified algorithm for safely postponing diagnostic imaging for pulmonary embolism (PE). At the index visit, patients were identified as being at high or low risk of PE; the former received full dosage low molecular weight heparin while the latter were left untreated until performance of diagnostic imaging (max 72 hours). During this period, no thromboembolic events occurred in low-risk patients (0/211, 0.% [upper 95% CI 0.9%]); only one event occurred in those at high-risk (1/125, 0.8% [upper 95% CI, 1.2]). Our study demonstrates that diagnostic imaging for PE can be safely deferred for up to 3 days