Hydroxyurea: a reappraisal of its cutaneous side effects and their management

Skin Malignancies Due to Anti-Cancer Therapies

Skin cancers involve a significant concern in cancer therapy due to their association with various treatment modalities. This comprehensive review explores the increased risk of skin cancers linked to different anti-cancer treatments, including classic immunosuppressants such as methotrexate (MTX), chemotherapeutic agents such as fludarabine and hydroxyurea (HU), targeted therapies like ibrutinib and Janus Kinase inhibitors (JAKi), mitogen-activated protein kinase pathway (MAPKP) inhibitors, sonic hedgehog pathway (SHHP) inhibitors, and radiotherapy. MTX, a widely used immunosuppressant in different fields, is associated with basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (cSCC), and cutaneous melanoma (CM), particularly at higher dosages. Fludarabine, HU, and other chemotherapeutic agents increase the risk of non-melanoma skin cancers (NMSCs), including cSCC and BCC. Targeted therapies like ibrutinib and JAKi have been linked to an elevated incidence of NMSCs and CM. MAPKP inhibitors, particularly BRAF inhibitors like vemurafenib, are associated with the development of cSCCs and second primary melanomas (SPMs). SHHP inhibitors like vismodegib have been linked to the emergence of cSCCs following treatment for BCC. Additionally, radiotherapy carries carcinogenic risks, especially for BCCs, with increased risks, especially with younger age at the moment of exposure. Understanding these risks and implementing appropriate screening is crucial for effectively managing patients undergoing anti-cancer therapies.

Hydration of N-Hydroxyurea from Ab Initio Molecular Dynamics Simulations

N-Hydroxyurea (HU) is an important chemotherapeutic agent used as a first-line treatment in conditions such as sickle cell disease and β-thalassemia, among others. To date, its properties as a hydrated molecule in the blood plasma or cytoplasm are dramatically understudied, although they may be crucial to the binding of HU to the radical catalytic site of ribonucleotide reductase, its molecular target. The purpose of this work is the comprehensive exploration of HU hydration. The topic is studied using ab initio molecular dynamic (AIMD) simulations that apply a first principles representation of the electron density of the system. This allows for the calculation of infrared spectra, which may be decomposed spatially to better capture the spectral signatures of solute-solvent interactions. The studied molecule is found to be strongly hydrated and tightly bound to the first shell water molecules. The analysis of the distance-dependent spectra of HU shows that the E and Z conformers spectrally affect, on average, 3.4 and 2.5 of the closest H2O molecules, respectively, in spheres of radii of 3.7 Å and 3.5 Å, respectively. The distance-dependent spectra corresponding to these cutoff radii show increased absorbance in the red-shifted part of the water OH stretching vibration band, indicating local enhancement of the solvent's hydrogen bond network. The radially resolved IR spectra also demonstrate that HU effortlessly incorporates into the hydrogen bond network of water and has an enhancing effect on this network. Metadynamics simulations based on AIMD methodology provide a picture of the conformational equilibria of HU in solution. Contrary to previous investigations of an isolated HU molecule in the gas phase, the Z conformer of HU is found here to be more stable by 17.4 kJ·mol-1 than the E conformer, pointing at the crucial role that hydration plays in determining the conformational stability of solutes. The potential energy surface for the OH group rotation in HU indicates that there is no intramolecular hydrogen bond in Z-HU in water, in stark contrast to the isolated solute in the gas phase. Instead, the preferred orientation of the hydroxyl group is perpendicular to the molecular plane of the solute. In view of the known chaotropic effect of urea and its N-alkyl-substituted derivatives, N-hydroxyurea emerges as a unique urea derivative that exhibits a kosmotropic ordering of nearby water. This property may be of crucial importance for its binding to the catalytic site of ribonucleotide reductase with a concomitant displacement of a water molecule.

Clinical Insights and Dermatological Recommendations for Non-Melanoma Skin Cancers (NMSCs) in Long-Term Hydroxyurea (HU) Therapy

Hydroxyurea (HU), an anti-metabolite ribonucleotide reductase inhibitor, is commonly used to treat several myeloproliferative disorders, including polycythemia vera. However, patients receiving long-term treatment with HU may experience a variety of cutaneous side effects, with non-melanoma skin cancers (NMSCs) emerging as the most challenging and destructive. HU-induced carcinogenesis can be attributed to both the drug's mutagenic potential and impaired DNA repair following damage by external triggers such as ultraviolet light. We report a unique case of multiple aggressive NMSCs distributed within sun-exposed areas in an 81-year-old woman receiving chronic therapy with HU for 15 years. The case draws the clinician's attention to the increased incidence of NMSCs in this population and highlights the need for regular dermatologic monitoring. We also elaborate relevant insights and recommendations to assist healthcare providers in managing HU-related NMSCs development and progression.

Atrial fibrillation and peripheral arterial disease define MPN patients with very high risk of thrombosis

Myeloproliferative neoplasms (MPNs) are associated with a high risk of thrombotic and hemorrhagic complications, especially in elderly patients. Atrial fibrillation (AF) and peripheral arterial disease (PAD), also frequently discovered in aging patients, are associated with similar complications. We analysed the incidence and complication rates of AF and PAD in a large cohort of MPN patients. In total, 289/1113 patients (26 %) suffered at least one of these diseases as follows: 179 (16.1 %) with AF alone, 81 with PAD alone (7.3 %) and 29 (2.6 %) with both conditions. Postdiagnosis thrombotic events were observed in 31.3 % of AF patients (p = 0.002, OR = 1.80 [1.23;2.61]), 35.8 % of PAD patients (p = 0.002, OR = 2.21[1.31;3.67]) and 62.1 % of AF/PAD patients (p < 0.0001, OR = 6.47 [2.83;15.46]) compared to 20.1 % of no-AF/no-PAD patients. Postdiagnosis hemorrhagic events were also identified in 17.9 %, 16 %, 24.1 % and 10.1 % of AF, PAD, AF/PAD, and no-AF/no-PAD patients, respectively (p = 0.003). This significantly higher risk of thrombosis/bleeding was also observed in patients <60 years old. AF and PAD were significant risk factors for both thrombotic and hemorrhagic risks in multivariate analysis. We identified AF and PAD as criteria for high risk of thrombosis, hemorrhage, and death, emphasizing the interest in early detection and efficient treatment of these conditions.

Hiperpigmentação Mucocutânea Associada à Terapia de Hidroxiureia em Paciente com Trombocitemia Essencial: Relato de Caso

Introdução: A hiperpigmentação mucocutânea é uma condição dermatológica que pode estar relacionada a tratamentos quimioterápicos, a exemplo das terapias com uso de hidroxiureia (HU). A HU é um fármaco citostático de amplo uso nas doenças mieloproliferativas e compõe a principal linha de tratamento da trombocitemia essencial (TE). O presente estudo tem por objetivo relatar um caso raro de hiperpigmentação mucocutânea em um paciente com TE. Relato do caso: Paciente do sexo masculino, 68 anos de idade, 89 kg, com diagnóstico de TE, em uso de HU 2 g/dia. Com três meses de terapia, apresentou lesões hiperpigmentadas de coloração acastanhadas em pele das mãos e mucosa oral (língua). Em decisão partilhada com o médico-assistente, o paciente optou pela continuação do uso do medicamento. Após seis anos de acompanhamento, as lesões mantêm-se estáveis. Conclusão: A hiperpigmentação mucocutânea associada à terapia com HU é um evento benigno secundário ao uso do fármaco e não exige a interrupção de uso, porém, sua retirada, ou redução das doses, geralmente leva à diminuição ou ao desaparecimento das lesões.

Second Cancer Onset in Myeloproliferative Neoplasms: What, When, Why?

The risk of developing a solid cancer is a major issue arising in the disease course of a myeloproliferative neoplasm (MPN). Although the connection between the two diseases has been widely described, the backstage of this complex scenario has still to be explored. Several cellular and molecular mechanisms have been suggested to link the two tumors. Sometimes the MPN is considered to trigger a second cancer but at other times both diseases seem to depend on the same source. Increasing knowledge in recent years has revealed emerging pathways, supporting older, more consolidated theories, but there are still many unresolved issues. Our work aims to present the biological face of the complex clinical scenario in MPN patients developing a second cancer, focusing on the main cellular and molecular pathways linking the two diseases.

Non-melanoma Skin Cancers in Patients on Hydroxyurea for Philadelphia Chromosome-Negative Myeloproliferative Neoplasms: A Systematic Review

Hydroxyurea (HU) or hydroxycarbamide is a cytotoxic antimetabolite widely used to treat Philadelphia chromosome-negative Myeloproliferative Neoplasms (Ph-MPN) like Polycythemia Vera (PV), Essential Thrombocythemia (ET), and Primary Myelofibrosis (PMF). Patients with Ph-MPN are at an increased risk of Non-melanoma skin cancers (NMSC). The cause of this finding remains uncertain. In this systematic review, we would like to know if chronic use of HU in this population is responsible for the sudden onset of NMSC. The results obtained will help the patients and clinicians with early diagnosis of cutaneous lesions and in optimizing the current treatment options for MPN. We conducted a multi-database literature search, applied eligibility criteria and quality assessment tools to the studies extracted, with an intention to include only fair to high-quality articles. We analyzed six observational studies and four traditional reviews. Two out of 10 studies concluded that no relationship exists between the incidence of NMSC and HU. The remaining eight studies indicated the association. According to these studies, the possible risk factors include old age, excessive exposure to sunlight, higher doses, and prolonged HU therapy duration. Ultraviolet (UV) radiation and HU play a combined role in carcinogenesis. Periodic dermatologic screening is essential in these patients. Prompt biopsy and accurate diagnosis can prevent the progression of cancer and decrease the associated morbidity and mortality. True incidence and causation cannot be ascertained due to the scarcity of research on this topic. Multi-center prospective studies in large groups of Ph-MPN patients are recommended to determine the temporal relationship between NMSC and HU treatment.

A review of hydroxyurea-related cutaneous adverse events

Introduction: Hydroxyurea (HU) is an S-phase specific oral chemotherapeutic agent that inhibits ribonucleotide diphosphate reductase. It is the most common used cytoreductive drug in patients (pts) with BCR-ABL1 negative myeloproliferative neoplasms (MPN) and sickle cell disease (SCD). The World Health Organization lists HU as an "essential drug". Although most patients tolerate HU well, cutaneous adverse events (CAE) are frequent side effects and may limit its long-term use. This has become increasingly evident in recent years, especially in MPN patients, where CAE were previously underestimated and underdiagnosed.Areas covered: In this review, we present the available literature on HU-related CAE in MPN patients. In particular, data from a recently published and so far, only prospective non-interventional study investigating CAE in 172 MPN patients will be discussed in detail and compared with previously available data. Finally, we give an overview of the management of HU-related CAE in MPN patients and provide recommendations on the practical clinical approach.Expert opinion: In clinical practice, HU associated CAE are common and have important diagnostic and therapeutic consequences. Therefore, they should be considered in all MPN patients treated with HU in the future.