Imatinib, dasatinib and nilotinib: a review of adverse cutaneous reactions with emphasis on our clinical experience

Keratosis Pilaris-like Eruption during Treatment of Chronic Myeloid Leukemia with Tyrosine Kinase Inhibitors: Literature Review and Report of a Case Related to Imatinib

The advent of tyrosine kinase inhibitors (TKIs) blocking BCR-ABL activity has revolutionized the therapeutic management of patients with chronic myeloid leukemia (CML). Adverse cutaneous reactions (ACRs) are common nonhematologic adverse events associated with the use of BCR-ABL TKIs. A characteristic pattern of eruption resembling keratosis pilaris (KP) has been described in patients treated with these drugs, especially nilotinib and dasatinib. The pathogenesis of this ACR is still unknown. This type of reaction appears to be uncommon with imatinib. Here, we report the case of an elderly patient with an asymptomatic KP-like eruption, which appeared one month after starting treatment with imatinib for CML. The case presentation is accompanied by a review of similar reactions in patients with CML treated with BCR-ABL inhibitors, attempting to make an excursus on the molecular targets of such drugs and possible mechanisms underlying this ACR.

Dasatinib-Induced Transverse Melanonychia

Introduction

Transverse melanonychia, characterized by grey to black pigmented bands traversing the nail plate, can occur as a side-effect of certain medications. While no documented reports specifically associate dasatinib, a tyrosine kinase inhibitor used in the treatment of chronic myeloid leukaemia (CML) and acute lymphoblastic leukaemia, with nail changes, we present a case of transverse melanonychia possibly related to dasatinib therapy.

Case Report

A 54-year-old male with CML, receiving dasatinib for 1.5 years, presented with transverse pigmented lines involving all fingernails and toenails. Clinical examination revealed discrete bands of transverse melanonychia in the nails. Onychoscopy of all finger- and toenails revealed multiple longitudinal grey lines within transverse grey bands of homogeneous chromonychia. Based on clinical presentation, onychoscopic features, and temporal association with dasatinib therapy, a provisional diagnosis of dasatinib-induced transverse melanonychia was made.

Discussion

The exact mechanisms underlying melanonychia are not fully understood but may involve nail matrix or toxicity, stimulation of nail-matrix melanocytes, or drug deposition within the nail plate. This case highlights the possibility of dasatinib-induced transverse melanonychia and underscores the importance of monitoring and evaluating nail changes in patients undergoing dasatinib treatment.

Perspectives of data science in preclinical safety assessment

The data landscape in preclinical safety assessment is fundamentally changing because of not only emerging new data types, such as human systems biology, or real-world data (RWD) from clinical trials, but also technological advancements in data-processing software and analytical tools based on deep learning approaches. The recent developments of data science are illustrated with use cases for the three factors: predictive safety (new in silico tools), insight generation (new data for outstanding questions); and reverse translation (extrapolating from clinical experience to resolve preclinical questions). Further advances in this field can be expected if companies focus on overcoming identified challenges related to a lack of platforms and data silos and assuring appropriate training of data scientists within the preclinical safety teams.

Adverse reactions after treatment with dasatinib in chronic myeloid leukemia: Characteristics, potential mechanisms, and clinical management strategies

Dasatinib, a second-generation tyrosine kinase inhibitor, is recommended as first-line treatment for patients newly diagnosed with chronic myeloid leukemia (CML) and second-line treatment for those who are resistant or intolerant to therapy with imatinib. Dasatinib is superior to imatinib in terms of clinical response; however, the potential pulmonary toxicities associated with dasatinib, such as pulmonary arterial hypertension and pleural effusion, may limit its clinical use. Appropriate management of dasatinib-related severe events is important for improving the quality of life and prognosis of patients with CML. This review summarizes current knowledge regarding the characteristics, potential mechanisms, and clinical management of adverse reactions occurring after treatment of CML with dasatinib.

Discoidin domain receptor 1 may be involved in biological barrier homeostasis

WHAT IS KNOWN AND OBJECTIVE

Discoidin domain receptor 1 (DDR1) is a receptor tyrosine kinase involved in the pathological processes of several diseases, such as keloid formation, renal fibrosis, atherosclerosis, tumours, and inflammatory processes. The biological barrier is the first line of defence against pathogens, and its disruption is closely related to diseases. In this review, we attempt to elucidate the relationship between DDR1 and the biological barrier, explore the potential biological value of DDR1, and review the current research status and clinical potential of DDR1-selective inhibitors.

METHODS

We conducted an extensive literature search on PubMed to collect studies on the relevance of DDR1 to biological barriers and DDR1-selective inhibitors. With these studies, we explored the relationship between DDR1 and biological barriers and briefly reviewed representative DDR1-selective inhibitors that have been reported in recent years.

RESULTS AND DISCUSSION

First, the review of the potential mechanisms by which DDR1 regulates biological barriers, including the epithelial, vascular, glomerular filtration, blood-labyrinth, and blood-brain barriers. In the body, DDR1 dysfunction and aberrant expression may be involved in the homeostasis of the biological barrier. Secondly, the review of DDR1 inhibitors reported in recent years shows that DDR1-targeted inhibition is an attractive and promising pharmacological intervention.

WHAT IS NEW AND CONCLUSIONS

This review shows that DDR1 is involved in various physiological and pathological processes and in the regulation of biological barrier homeostasis. However, studies on DDR1 and biological barriers are still scarce, and further studies are needed to elucidate their specific mechanisms. The development of targeted inhibitors provides a new direction and idea to study the mechanism of DDR1.

Nilotinib-induced elephantine psoriasis in a chronic myeloid leukemia patient: A rare case report and literature review

Tyrosine kinase inhibitors are anticancer drugs that disrupt signal transduction pathways in protein kinases by different mechanisms. This group of pharmacologic agents has significantly improved the outcome of patients with chronic myeloid leukemia. However, their effect is not limited to cancer cells, and various complications, particularly cutaneous reactions, have been reported. We report a very rare case of a 35-year-old female with a history of chronic myeloid leukemia who presented with elephantine psoriasis after the treatment with nilotinib.

Conclusions: This case highlights a critical side effect of tyrosine kinase inhibitors. Awareness of this subject can be useful for better management of similar patients.

Discrimination of hand-foot skin reaction caused by tyrosine kinase inhibitors based on direct keratinocyte toxicity and vascular endothelial growth factor receptor-2 inhibition

Tyrosine kinase inhibitors (TKIs) are molecular-targeted anticancer drugs. Their benefits are limited by dermal toxicities, including hand-foot skin reaction (HFSR), which is commonly found in skin areas subjected to friction. The present study aimed to explain the incidence of HFSR in patients treated with TKIs by focusing on keratinocyte toxicity and inhibition of vascular endothelial growth factor receptor (VEGFR), which plays an essential role in angiogenesis. Mice with gene knockout for the immunosuppressive cytokine interleukin-10 exhibited HFSR-like phenotypes, such as cytotoxicity in keratinocytes and increased number and size of blood vessels after repeated doses of regorafenib, sorafenib, and pazopanib, all of which cause high incidence of HFSR, in combination with tape-stripping mimicking skin damage at the friction site. Comprehensive examination of the direct cytotoxic effects of 21 TKIs on primary cultured human keratinocytes revealed that 18 of them reduced the cell viability dose-dependently. Importantly, the ratio of the trough concentration in patients (C_trough) to the LC₅₀ values of cell viability reduction was higher than unity for four HFSR-inducing TKIs, suggesting that these TKIs cause keratinocyte toxicity at clinically relevant concentrations. In addition, eight HFSR-inducing TKIs caused inhibition of VEGFR-2 kinase activity, which was validated by their ratios of C_trough to the obtained IC_50,VEGFR-2 of more than unity. All 12 TKIs with no reported incidence of HFSR exhibited less than unity values for both C_trough/LC_{50,keratinocytes} and C_trough/IC_50,VEGFR-2. These results suggested that a combination of keratinocyte toxicity and VEGFR-2 inhibition may explain the incidence of HFSR upon TKI usage in humans.

Tyrosine kinase inhibitor nilotinib induced palmoplantar erythrodysesthesia: A rare case

Introduction

Nilotinib is a second generation Tyrosine Kinase inhibitor (TKI) used in the treatment of Chronic Myeloid Leukemia (CML). The development of tyrosine kinase inhibitors has transformed chronic phase chronic myeloid leukemia from a disease with a poor prognosis to a treatable chronic disease. Long-term treatment with tyrosine kinase inhibitors means that patients must be clinically managed and monitored for years. While under Nilotinib tretament, the development of palmoplantar erythrodyesthesia is a very rare condition compared to other oncological drugs.

Case report

A 66-year-old male patient, who was diagnosed with chronic phase CML in 2019 had been placed under imatinib treatment . He had major molecular response loss in 2021, and was started on second generation TKI nilotinib 2  ×  400mg/day, considering his comorbidities. We present a case of a 66-year-old patient with CML who developed palmoplantar erythrodysesthesia on the 21st day starting nilotinib treatment.

Conclusion

It is important to manage the side effects that develop in long-term treatments. Adverse events can have a negative impact on patient compliance and quality of life and lead to poor clinical outcomes Our case is the first to develop PPE after beginning nilotinib use. We present this phenomenon to raise awareness and ignite a review of management strategies.In this case, we wanted to emphasize the importance of managing side effects.

Cutaneous side effects in a cohort of patients with chronic myeloid leukemia treated with tyrosine kinase inhibitors: General description and further characterization, correlation with photoexposition and study of hypopigmentation as treatment's prognostic factor

Cutaneous adverse effects (AE) related to tyrosine-kinase inhibitor (TKI) drugs have been mainly described as case reports. We have characterized their appearance and correlation with patient's photoexposition habits and, further, with treatment response, in 61 patients with chronic myelogenous leukemia (CML) treated with TKI drugs. We have found hypopigmentation in 49.2% of the cases and a statistically significant association with interferon (IFN) intake. Eyelid edema's frequency was 45.4%. Mean photo-exposure was 1.95 h/day and only 8.3% of the patients used sunscreen daily. 44.3% of the patients reported a lighter skin color with the treatment and a statistically significant relationship with conjunctival hemorrhage was also found. Concordance between patients and dermatologist was moderate (kappa index 0.41). We found xerosis (21.3%), eczematous eruptions (21.3%), melasma (4.9%) and other isolated skin problems (ie, granulomatous panniculitis) in up to 16.4% of cases. Appearance of hypopigmented macules is associated to vascular conjunctival fragility and these patients need a slightly longer time to reach a complete molecular response, but without additional changes in survival or relapse frequency. We have stablished a specific dermatologic diagnosis in all the cases and we have not found the previously published as maculopapular rashes. Hypopigmentation, the more frequent AE, was not perceived as a relevant side effect. Photosensitivity, in our cases, was not reported, although imatinib-treated patients avoided sun-exposure. In addition, we identified some nonpreviously described dermatologic conditions in patients taking TKI drugs, like granulomatous panniculitis tufted folliculitis or oral spindle cell lipoma.

Pharmacology of tyrosine kinase inhibitors in chronic myeloid leukemia; a clinician's perspective

OBJECTIVE

In this review, we have summarized the pharmacokinetics, pharmacodynamics and adverse effects of imatinib, dasatinib, nilotinib, bosutinib, ponatinib and radotinib with focus on pharmacogenomic studies with clinical end points. We have discussed the key phase 3 trials of tyrosine kinase inhibitors (TKI) comparing with each other, treatment free remission (TFR) and selection of TKI. Upcoming concepts and related trials in the management of chronic myeloid leukemia (CML) along with future directions have been touched upon.

EVIDENCE ACQUISITION

PubMed, Embase, Google, Cochrane library and Medline were searched to identify relevant literature for the review. Clinicaltrial.gov was searched for upcoming data and trials.

RESULTS

There are lot of gap in pharmacokinetics and pharmacodynamics of TKI. Imatinib appears to be the safest TKI. Newer TKI's achieve better achievement of therapeutic milestones, deeper molecular response and less chances of progression of CML compared to imatinib. Newer TKI appears to be better choice for achieving TFR. When the objective is survival, imatinib is still the TKI of choice. Primary prophylaxis with antiplatelet drugs for TKI having cardiovascular and thromboembolic side effects should be considered.

CONCLUSION

Pharmacogenetic data of TKI is still immature to guide in therapeutic decision making in clinical practice. There is need for further research in pharmacology and pharmacogenomics of newer TKI's. Randomized controlled trials are required to decide the optimum TKI for TFR. Safe and effective TKI for targeting T315I mutation, CML accelerated phase and blast crisis are an active area of research.

Skin lesions in chronic myeloid leukemia patients during dasatinib treatment

Purpose

In our work we sought to define the prevalence rates of cutaneous events during dasatinib therapy in chronic myeloid leukemia (CML) patients and to investigate the clinical and pathological characteristics of these reactions.

Patients and methods

In our institution, 67 CML patients were treated with dasatinib. it was given as first line treatment in 26 (39%) and subsequent treatment in 41 (61%) CML patients. Flow cytometry analysis of peripheral blood and cutaneous biopsy was done on all CML patients with dermatological lesions appearing during dasatinib treatment.

Results

Among 67 CML patients, 4 (5.9%) showed skin lesions during dasatinib treatment. The cutaneous manifestations were not generalized but mainly located on the back, abdomen, thorax or leg regions. The patients did not show peripheral lymphocytosis at the time when skin lesions appeared. Overall, histological analysis showed that the skin lesions were characterized by a mild perivascular small CD8+ T lymphocytes infiltrate with minimal epidermotropism.

Conclusion

The unusual T cytotoxic cutaneous infiltrate demonstrated in our CML cases could be the expression of a dasatinib-promoted lymphocyte expansion. However, the heterogeneity of the dermatologic manifestations reported in our CML patients could also be related to unknown factors specific to each CML patient. Our work highlights the finding that skin lesions may be associated with dasatinib treatment and that they should not be confused with viral or bacterial infections but rather interpreted as the clinical expression of lymphocytosis promoted by this TKI.

Skin Infections

Cutaneous infections are common in immunocompromised patients. Neutropenia predisposes patients to fungal, bacterial and viral infections. Antibacterial antifungal and antiviral prophylaxis have caused a significant reduction in some of these infections.

There are two main types of cutaneous infections : primary cutaneous infections and cutaneous manifestations of a disseminated infection. In the latter, skin lesions may be the window to disseminated bloodstream infection and the first and only evidence of a disseminated life threatening infection.

The diagnosis may be at your fingertips; therefore a thorough skin exam is the clue. However, it’s also important to know the characteristic lesions associated with different infections. It will help expedite diagnosis so appropriate treatment is initiated promptly in neutropenic patients, which can be lifesaving.

In a retrospective study of 43 neutropenic febrile patients with cutaneous lesions, fungal infections were the most frequent, and nodular lesions on the lower extremities were the most prevalent (Naorungroj and Aiempanakit, J Am Acad Dermatol 74:AB166, 2016).

Skin biopsy for pathological study and culture remains the gold standard and should be obtained early to confirm the suspected diagnosis. In these immunocompromised patients the inflammatory response is altered by either the primary disease or its treatment. Therefore, routine pathogens may present in an atypical fashion, with diminished or absent induration, erythema, or pustulation in response to bacterial resulting cutaneous infection without typical cellulitis (Urabe, Clin Infect Dis 39:S53–S55, 2004). Skin lesions are evaluated not only by morphology, but also in the context of the clinical setting and biopsy result. The skin biopsy is inexpensive, relatively noninvasive and without contraindication, and may avoid the need for more invasive procedures such an open lung biopsy (Grossman, et al., Cutaneous manifestations of infection in the immunocompromised host. Springer Science+Business Media, LLC, New York, 2012).

In addition to antimicrobial therapy, surgery should not be postponed in the face of progressive skin and soft tissue infection in this population (Brzozowski and Ross, J Hand Surg Br 22:679–680, 1997).

Blistering and Skin Fragility Due to Imatinib Therapy: Loss of Laminin and Collagen IV as a Possible Cause of Cutaneous Basement Membrane Instability

Imatinib mesylate (Glivec; Novartis AG, Basel, Switzerland) is a tyrosine kinase inhibitor which is used in the treatment of oncologic diseases like chronic myeloid leukemia and gastrointestinal stroma tumor (GIST). Among cutaneous side effects, bullous reactions are rare. The authors describe the case of a 66-year-old woman developing blistering and skin fragility on her hands, foot, lower legs, and back after intake of imatinib for treatment of GIST. Biopsy showed vacuolar alteration at the dermoepidermal junction (DEJ) associated with a few lymphocytes and a subepidermal blister. The upper papillary dermis below the vacuolar alteration and below the blister showed hyalinization and loss of elastic microfibrils. Direct immunofluorescence was negative for deposits of immunoglobulins. Immunofluorescence on cryosections revealed loss of laminin and collagen IV in vacuoles at the DEJ. Electron microscopy showed dissolution of lamina lucida and lamina densa of the basement membrane below as well as next to the vacuoles and blister. In conclusion, the authors present the first patient with GIST with blistering and skin fragility due to imatinib therapy. As a pathophysiological explanation the authors propose loss of laminin and collagen IV at the DEJ leading to basement membrane instability and blistering. This case also suggests additional features reminiscent of lichen sclerosus induced by imatinib, a drug which is actually known for its antifibrotic effects.

European LeukemiaNet recommendations for the management and avoidance of adverse events of treatment in chronic myeloid leukaemia

Most reports on chronic myeloid leukaemia (CML) treatment with tyrosine kinase inhibitors (TKIs) focus on efficacy, particularly on molecular response and outcome. In contrast, adverse events (AEs) are often reported as infrequent, minor, tolerable and manageable, but they are increasingly important as therapy is potentially lifelong and multiple TKIs are available. For this reason, the European LeukemiaNet panel for CML management recommendations presents an exhaustive and critical summary of AEs emerging during CML treatment, to assist their understanding, management and prevention. There are five major conclusions. First, the main purpose of CML treatment is the antileukemic effect. Suboptimal management of AEs must not compromise this first objective. Second, most patients will have AEs, usually early, mostly mild to moderate, and which will resolve spontaneously or are easily controlled by simple means. Third, reduction or interruption of treatment must only be done if optimal management of the AE cannot be accomplished in other ways, and frequent monitoring is needed to detect resolution of the AE as early as possible. Fourth, attention must be given to comorbidities and drug interactions, and to new events unrelated to TKIs that are inevitable during such a prolonged treatment. Fifth, some TKI-related AEs have emerged which were not predicted or detected in earlier studies, maybe because of suboptimal attention to or absence from the preclinical data. Overall, imatinib has demonstrated a good long-term safety profile, though recent findings suggest underestimation of symptom severity by physicians. Second and third generation TKIs have shown higher response rates, but have been associated with unexpected problems, some of which could be irreversible. We hope these recommendations will help to minimise adverse events, and we believe that an optimal management of them will be rewarded by better TKI compliance and thus better CML outcomes, together with better quality of life.

A successful approach to overcome imatinib-induced skin toxicity in a GIST patient

Since the introduction of tyrosine kinase inhibitors in gastrointestinal stromal tumor patients, the median survival of patients has increased from less than 1 to more than 5 years. The chronic use of a tyrosine kinase inhibitor has an impact on quality of life because of its toxicity. Adequate supportive therapy is therefore important. We describe a female patient with a metastatic gastrointestinal stromal tumor. During treatment with the c-KIT inhibitor imatinib, she developed severe therapy-limiting skin toxicity. After several different supportive attempts, the combination of doxycycline and clemastine proved to be the solution, enabling successful chronic treatment with imatinib. Chronic use of doxycycline and clemastine is useful in the management of skin toxicity caused by c-KIT inhibitors, enabling the needed long-term use of these kind of anticancer drugs without hampering the quality of life.

Xanthelasma palpebrarum: a new side effect of nilotinib

Chronic myeloid leucaemia (CML) is a chronic myeloproliferative disorder characterised by a reciprocal translocation between the chromosomes 9 and 22 resulting in constitutionally active tyrosine kinase signalling. BCR-ABL tyrosine kinase inhibitors (TKIs) are highly effective molecules in the treatment of CML. Unfortunately, these novel therapeutic agents are accompanied by various side effects, and haematological, cutaneous and metabolic abnormalities are among the most prevalent. Nilotinib, a second-generation TKI, has been shown to cause both--cutaneous lesions and lipid profile abnormalities. We present two CML cases developing xanthelasma palpebrarum while receiving nilotinib. Case 1 also acquired a lipid abnormality following the start of nilotinib therapy, while case 2 meanwhile stayed normolipidemic. In addition to a low cholesterol diet, atorvastatin was prescribed to case 1. Currently, both cases are normolipidemic and continuing their nilotinib therapy. Xanthelasma palpebrarum secondary to nilotinib therapy is new to the literature.

C-kit mutations determine dasatinib mechanism of action in HMC-1 neoplastic mast cells: dasatinib differently regulates PKCδ translocation in HMC-1(560) and HMC-1(560,816) cell lines

PURPOSE

The second generation of tyrosine kinase inhibitors is a group of compounds that inhibit c-kit receptor activity and therefore widely used in the treatment of mastocytosis. In this research, the relationship between the mechanism of action of tyrosine kinase inhibitors and protein kinase C is investigated in HMC-1(560) or HMC-1(560,816) cell lines.

RESULTS

From all the tyrosine kinase inhibitors tested, nilotinib is the compound that has the highest cytotoxic effect against HMC-1(560) mast cell line, while midostaurin is the most potent in HMC-1(560,816). Moreover, an increase on histamine release is observed after protein kinase C activation either in HMC-1(560) or HMC-1(560,816) cells. Furthermore, dasatinib increases histamine release in both mast cell lines, which could be related with the secondary reactions previously described in dasatinib-treated patients. Dasatinib also induces Ca(2+)-dependent protein kinase C isoforms translocation from the cytosol to the membrane, whereas protein kinase Cδ is translocated from the cytosol to the nucleus in the HMC-1(560,816) cell line, but not in HMC-1(560) cells.

CONCLUSION

Results obtained demonstrate that dasatinib induces an important cytotoxic effect in both HMC-1 cell lines and differently regulates protein kinase Cδ in HMC-1(560) and HMC-1(560,816) cells. Finally, our results confirm that PKCδ is an essential target for dasatinib.

Management of adverse events associated with tyrosine kinase inhibitors in chronic myeloid leukemia

Tyrosine kinase inhibitors (TKIs) targeting the breakpoint cluster region-Abelson 1 (BCR-ABL1) oncoprotein represent an outstanding progress in chronic myeloid leukemia (CML), and long-term survival has become a reality. However, the majority of patients need to be treated during their entire life span; thus, outcome does not solely depend on treatment efficacy but also on how well therapy is tolerated. TKIs have an overall favorable safety profile in clinical practice. Although many patients may encounter adverse events, these usually occur early after treatment initiation, are mild to moderate in intensity and resolve spontaneously, or are easily controlled with adequate supportive care. Whenever treatment interruption is necessary, re-exposition to the same TKI or switch to an alternative TKI is successful in the majority of the cases. However, long-term safety issues have not been fully elucidated at present, especially for new-generation TKIs. Recent evidence has emerged that these new agents may sometimes impinge on vital organs such as the heart and lung in an irreversible fashion especially when comorbidities are present; thus, decision regarding of which TKI should be used must take into account disease-related, TKI-related, and patient-related variables. The purpose of this article is to provide an up-to-date review of common adverse events associated with TKIs and how these events may be optimally managed.

A newborn with teratogenic effect of imatinib mesylate: a very rare case report

OBJECTIVE

To report a case of teratogenic effect of imatinib mesylate (IM) in a newborn, whose mother was suffering from chronic myelogenous leukemia and was treated with IM for 4 years, including during her pregnancy.

CASE PRESENTATION AND INTERVENTION

The newborn was diagnosed with microtia of the right ear, preauricular tag on the left side, absence of right depressor angular oris muscle, and imperforate anus. Infantogram showed dextrocardia, hemivertebrae in the thoracic region and cervical spina bifida occulta. The newborn was operated on for the imperforate anus and was discharged in good condition.

CONCLUSION

This case revealed that IM is not safe for the fetus and leads to teratogenicity. Hence, we recommend that pregnant women should not be treated with IM.

Tyrosine kinase inhibitors as reversal agents for ABC transporter mediated drug resistance

Tyrosine kinases (TKs) play an important role in pathways that regulate cancer cell proliferation, apoptosis, angiogenesis and metastasis. Aberrant activity of TKs has been implicated in several types of cancers. In recent years, tyrosine kinase inhibitors (TKIs) have been developed to interfere with the activity of deregulated kinases. These TKIs are remarkably effective in the treatment of various human cancers including head and neck, gastric, prostate and breast cancer and several types of leukemia. However, these TKIs are transported out of the cell by ATP-binding cassette (ABC) transporters, resulting in development of a characteristic drug resistance phenotype in cancer patients. Interestingly, some of these TKIs also inhibit the ABC transporter mediated multi drug resistance (MDR) thereby; enhancing the efficacy of conventional chemotherapeutic drugs. This review discusses the clinically relevant TKIs and their interaction with ABC drug transporters in modulating MDR.

Imatinib mesylate-induced pseudoporphyria in two children

Imatinib mesylate was the first of several tyrosine kinase inhibitors approved for use in the treatment of a number of human cancers. Adverse cutaneous reactions to imatinib are common. Pseudoporphyria has been infrequently reported in adults undergoing imatinib therapy for chronic myeloid leukemia. We present two children with pseudoporphyria induced by imatinib therapy for hematologic malignancies. In view of the burgeoning use of imatinib in children, physicians should be aware that pseudoporphyria may develop as a consequence of imatinib therapy.

Multiple squamous cell carcinomas following introduction of nilotinib

BACKGROUND

Nilotinib is a second generation tyrosine kinase inhibitor, used in the treatment of chronic myelogenous leukaemia (CML).

METHODS

We assessed a 72-year-old woman who was treated with nilotinib for CML.

RESULTS

During the year following commencement of nilotinib, the patient developed eight squamous cell carcinomas (SCCs) on her legs.

CONCLUSIONS

Development of SCC is a previously unreported adverse reaction to nilotinib.

Vinculin phosphorylation differentially regulates mechanotransduction at cell-cell and cell-matrix adhesions

Vinculin phosphorylation on residue Y822 is necessary for cell stiffening in response to tension on cadherins but not integrins.

Cells experience mechanical forces throughout their lifetimes. Vinculin is critical for transmitting these forces, yet how it achieves its distinct functions at cell–cell and cell–matrix adhesions remains unanswered. Here, we show vinculin is phosphorylated at Y822 in cell–cell, but not cell–matrix, adhesions. Phosphorylation at Y822 was elevated when forces were applied to E-cadherin and was required for vinculin to integrate into the cadherin complex. The mutation Y822F ablated these activities and prevented cells from stiffening in response to forces on E-cadherin. In contrast, Y822 phosphorylation was not required for vinculin functions in cell–matrix adhesions, including integrin-induced cell stiffening. Finally, forces applied to E-cadherin activated Abelson (Abl) tyrosine kinase to phosphorylate vinculin; Abl inhibition mimicked the loss of vinculin phosphorylation. These data reveal an unexpected regulatory mechanism in which vinculin Y822 phosphorylation determines whether cadherins transmit force and provides a paradigm for how a shared component of adhesions can produce biologically distinct functions.

Drug-induced photoallergic and phototoxic reactions - an update

INTRODUCTION

Photoallergic and phototoxic medications continue to be an important concern for dermatologists. In the last 5 years, the list of phototoxic and photoallergic medications has expanded, as well as the testing tools used to screen for potential allergy. Currently available testing methods include the photoprick, photoscratch and illuminated intracutaneous tests. If the causative photosensitizer is not the test substance but a metabolite of the test substance, a systemic photoprovocation test can be utilized. Photodynamic therapy pro-photosensitizers have been shown to be sensitizers to visible light, while most other phototoxins respond to the UVA and/or UVB spectrum.

AREAS COVERED

This article reviews the findings of a PubMed search for the key words 'photosensitivity', 'photosensitive', 'phototoxicity', 'phototoxic', 'photoallergy' and 'photoallergic'. Articles published over the last 5 years were compared with those published earlier than this to find updated information on photo-reactions.

EXPERT OPINION

With the variety of new monoclonal antibodies, clinicians must remain up to date as to the drugs that can cause photo-reactions. There are new tests that can aid in assessing photo-reactions.