While the peptide and protein therapeutic market has developed significantly in the past decades, delivery has limited their use. Although oral delivery is preferred, most are currently delivered intravenously or subcutaneously due to degradation and limited absorption in the gastrointestinal tract. Therefore, absorption enhancers, enzyme inhibitors, carrier systems and stability enhancers are being studied to facilitate oral peptide delivery. Additionally, transdermal peptide delivery avoids the issues of the gastrointestinal tract, but also faces absorption limitations. Due to proteases, opsonization and agglutination, free peptides are not systemically stable without modifications. This review discusses oral and transdermal peptide drug delivery, focusing on barriers and solutions to absorption and stability issues. Methods to increase systemic stability and site-specific delivery are also discussed.

The oncoprotein Bcr-Abl drives aberrant downstream activity through trans-autophosphorylation of homo-oligomers in chronic myelogenous leukemia (CML).1,2 The formation of Bcr-Abl oligomers is achieved through the coiled-coil domain at the N-terminus of Bcr.3, 4 We have previously reported a modified version of this coiled-coil domain, CCmut2, which exhibits disruption of Bcr-Abl oligomeric complexes and results in decreased proliferation of CML cells and induction of apoptosis.5 A major contributing factor to these enhanced capabilities is the destabilization of the CCmut2 homo-dimers, increasing the availability to interact with and inhibit Bcr-Abl. Here, we included an additional mutation (K39E) that could in turn further destabilize the mutant homo-dimer. Incorporation of this modification into CCmut2 (C38A, S41R, L45D, E48R, Q60E) generated what we termed CCmut3, and resulted in further improvements in the binding properties with the wild-type coiled-coil domain representative of Bcr-Abl. A separate construct containing one revert mutation, CCmut4, did not demonstrate improved oligomeric properties and indicated the importance of the L45D mutation. CCmut3 demonstrated improved oligomerization via a two-hybrid assay as well as through colocalization studies, in addition to showing similar biologic activity as CCmut2. The improved binding between CCmut3 and the Bcr-Abl coiled-coil may be used to redirect Bcr-Abl to alternative subcellular locations with interesting therapeutic implications.

In doping control laboratories, autologous blood transfusions are currently detected using an indirect method that monitors changes in an athlete's hemoglobin concentration [Hb] and reticulocyte percent (Ret%) over time. The method is limited by the need for a phlebotomist to collect venous blood and the limited blood stability which requires temperature-controlled shipment and analysis within 72 hours. These limitations significantly reduce the number of samples collected from each athlete and thus the utility of the method. We have recently developed a method to measure immature reticulocytes (IRC) and red blood cells (RBC) in dried blood spots, which could replace the current venous blood method. In the DBS method, cell-specific proteins are digested with trypsin and measured by mass spectrometry. Two proteins, CD71 and Band3, are measured to count IRC and RBC, respectively. The method was tested in an autologous transfusion study consisting of 15 subjects who received blood and 11 subjects who received saline. After transfusion, the average CD71/Band3 ratio in the blood group was statistically different from the saline group at days 5, 6, 13, and 20. The average CD71/Band3 ratio decreased to a minimum of 61 ± 8% of baseline, while Ret% decreased to 75 ± 5% of baseline. Based on experimentally defined criteria, the CD71/Band3 ratio could detect 7 out of 10 blood transfusion subjects, while Ret% could detect 3 out of 10. Thus, the DBS method could improve detection of autologous transfusion and allow increased sample collection.

In 2012, ponatinib (Iclusig®), an orally available pan-BCR-ABL tyrosine kinase inhibitor (TKI) developed by ARIAD Pharmaceuticals, Inc., was approved by the US Food and Drug Administration for use in resistant or intolerant chronic myeloid leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL). Ponatinib is the only approved TKI capable of inhibiting BCR-ABL with the gatekeeper T315I kinase domain mutation, known to be the cause for 20% of resistant or relapsed CML cases. In 2013, ponatinib sales were temporarily suspended due to serious side effects seen in nearly 12% of the patient population. These side effects are thought to stem from the potent nature and pan-activity of this TKI. ARIAD Pharmaceuticals, Inc. has since been permitted to resume sales and marketing of ponatinib to a limited patient population with an expanded black box warning. In the following review, the use of ponatinib in CML and Ph+ALL will be discussed. Mechanisms of resistance in CML are discussed, which provide insight and background into the need for this third generation TKI, followed by the molecular design and pharmacology of ponatinib, which lead to its success as a therapeutic. Finally, the efficacy, safety, and tolerability of ponatinib will be highlighted, including summaries of the important clinical trials involving ponatinib as well as its current place in therapy.

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The oncoprotein Bcr-Abl, the causative agent of chronic myeloid leukemia (CML), requires homo-oligomerization via a coiled-coil domain to function.1–4 While tyrosine kinase inhibitors (TKIs) have shown great efficacy as treatment options for CML, their use may cause an acquisition of mutations in the tyrosine kinase domain which prevent TKI binding and lead to a loss in activity.5 Previously, we have shown that a rationally modified coiled-coil domain (CCmut3) can disrupt this oligomerization, inhibit proliferation, and induce apoptosis in CML cells.6 Here, we show that using the most recently approved TKI, ponatinib (Iclusig™), in combination with CCmut3 allows a dose reduction of ponatinib and increased therapeutic efficacy in vitro measured by reduction in kinase activity, induction of apoptosis via caspase-3/7 and 7AAD/Annexin V assays, and reduced transformative ability measured by a colony forming assay. The combination was effective not only in cells containing wild-type Bcr-Abl (K562, Ba/F3-p210) but also cells with Bcr-Abl containing the T315I mutation (Ba/F3-p210-T315I). In addition, we report for the first time the ability of CCmut3 alone to inhibit the T315I mutant form of Bcr-Abl. This novel combination may prove to be more potent than single agent therapies and should be further explored for clinical use.

The hematological module of the Athlete Biological Passport (ABP) is used for indirect detection of blood manipulations; however, the use of this method to detect doping, such as with microdoses of recombinant human erythropoietin (rhEPO), is problematic. For this reason, the sensitivity of ABP must be enhanced by implementing novel biomarkers. Here, we show that 5'-aminolevulinate synthase 2 (ALAS2) mRNAs are useful transcriptomic biomarkers to improve the indirect detection of rhEPO microdosing. Moreover, the sensitivity was sufficient to distinguish rhEPO administration from exposure to hypoxic conditions. Levels of mRNAs encoding carbonate anhydrase 1 (CA1) and solute carrier family 4 member 1 (SLC4A1) RNA, as well as the linear (L) and linear + circular (LC) forms of ALAS2 mRNA, were monitored for 16 days after rhEPO microdosing and during exposure to hypoxic conditions. ALAS2 mRNAs increased by 300% compared with the baseline values after rhEPO microdosing. Moreover, ALAS2 mRNAs were not significantly increased under hypoxic conditions. By contrast, CA1 mRNA was increased after both rhEPO microdosing and hypoxia, whereas SLC4A1 mRNA did not significantly increase under either condition. Furthermore, the analyses described here were performed using dried blood spots (DBSs), which provide advantages in terms of the sample collection, transport, and storage logistics. This study demonstrates that ALAS2 mRNA levels are sensitive and specific transcriptomic biomarkers for the detection of rhEPO microdosing using the hematological module of the ABP, and this method is compatible with the use of DBSs for anti-doping analyses.

Purpose The hydration status of an athlete at the time of a doping control sample collection is an important factor to consider when reviewing athlete biological passports (ABPs). Dehydration results in a reduction of the circulating plasma volume (PV), which may lead to artificially high values of some blood parameters. This study aimed to identify whether serum albumin could serve as a single marker of fluid shifts, which are not currently accounted for in the hematological passport. An additional marker could be used to assist experts when interpreting irregularities in the ABP. Methods Twelve subjects underwent multiple controlled exercise trials designed to induce varying levels of PV shifts. Pre‐exercise blood samples were collected to establish baseline values for individual passports. During exercise interventions, blood samples were collected before the start of exercise and at 10 minute, 1 hour, 2 hours, and 24 hours following exercise. Results Significant increases in hematological parameters – hemoglobin [Hb], hematocrit (HCT), albumin (ALB), and calculated OFF‐score – were identified at varying time points following fluid shift‐inducing exercise. Changes in ALB correlated strongly with changes in [Hb] (r = 0.753) and with estimated PV shifts (r = −0.764). In analyzing ABPs, the resulting increases in Hb did not trigger any atypical findings at 99% specificity. Perspective Monitoring changes in ALB longitudinally may assist experts when reviewing PV shifts in the biological passport.