Safety of pembrolizumab for resected stage III melanoma.

INTRODUCTION: Patients with resected stage III melanoma have a heterogeneous prognosis with an especially high risk of relapse for patients with stage IIIB, IIIC and IIID according to the 2018 classification in AJCC Cancer Staging Manual, 8th edition (AJCC-8). Ipilimumab was the first immune checkpoint inhibitor (ICI) to show prolonged overall survival (OS) but at the cost of high toxicity. Pembrolizumab and nivolumab are inhibitors of programmed cell death 1 (PD-1) and showed prolonged relapse-free survival (RFS) in patients with resected stage III melanoma at high risk of relapse compared to placebo and ipilimumab, respectively. AREAS COVERED: The aim of this article is to review the mechanisms of action, pharmacokinetics and safety data of pembrolizumab in resected stage III melanoma and to compare its safety profile to other immune checkpoint inhibitors for the same indication. EXPERT OPINION: Pembrolizumab as adjuvant therapy of resected stage III melanoma showed an acceptable safety profile, which is comparable to that in advanced melanoma. However, it caused one death. There is uncertainty about its benefits in AJCC-8 stage IIIA melanoma patients. Additionally, caution is required since OS and long-term safety data are not available yet.

Time slicing in 3D momentum imaging of the hydrogen molecular ion photo-fragmentation.

Photo-fragmentation of the hydrogen molecular ion was investigated with 800 nm, 50 fs laser pulses by employing a time slicing 3D imaging technique that enables the simultaneous measurement of all three momentum components which are linearly related with the pixel position and slicing time. This is done for each individual product particle arriving at the detector. This mode of detection allows us to directly measure the three-dimensional fragment momentum vector distribution without having to rely on mathematical reconstruction methods, which additionally require the investigated system to be cylindrically symmetric. We experimentally reconstruct the laser-induced photo-fragmentation of the hydrogen molecular ion. In previous experiments, neutral molecules were used as a target, but in this work, performed with molecular ions, the initial vibrational level populations are well-defined after electron bombardment, which facilitates the interpretation. We show that the employed time-slicing technique allows us to register the fragment momentum distribution that reflects the initial molecular states with greater detail, revealing features that were concealed in the full time-integrated distribution on the detector.

Regulation of mitogen-activated protein kinases in cardiac myocytes through the small G protein Rac1.

Small guanine nucleotide-binding proteins of the Ras and Rho (Rac, Cdc42, and Rho) families have been implicated in cardiac myocyte hypertrophy, and this may involve the extracellular signal-related kinase (ERK), c-Jun N-terminal kinase (JNK), and/or p38 mitogen-activated protein kinase (MAPK) cascades. In other systems, Rac and Cdc42 have been particularly implicated in the activation of JNKs and p38-MAPKs. We examined the activation of Rho family small G proteins and the regulation of MAPKs through Rac1 in cardiac myocytes. Endothelin 1 and phenylephrine (both hypertrophic agonists) induced rapid activation of endogenous Rac1, and endothelin 1 also promoted significant activation of RhoA. Toxin B (which inactivates Rho family proteins) attenuated the activation of JNKs by hyperosmotic shock or endothelin 1 but had no effect on p38-MAPK activation. Toxin B also inhibited the activation of the ERK cascade by these stimuli. In transfection experiments, dominant-negative N17Rac1 inhibited activation of ERK by endothelin 1, whereas activated V12Rac1 cooperated with c-Raf to activate ERK. Rac1 may stimulate the ERK cascade either by promoting the phosphorylation of c-Raf or by increasing MEK1 and/or -2 association with c-Raf to facilitate MEK1 and/or -2 activation. In cardiac myocytes, toxin B attenuated c-Raf(Ser-338) phosphorylation (50 to 70% inhibition), but this had no effect on c-Raf activity. However, toxin B decreased both the association of MEK1 and/or -2 with c-Raf and c-Raf-associated ERK-activating activity. V12Rac1 cooperated with c-Raf to increase expression of atrial natriuretic factor (ANF), whereas N17Rac1 inhibited endothelin 1-stimulated ANF expression, indicating that the synergy between Rac1 and c-Raf is potentially physiologically important. We conclude that activation of Rac1 by hypertrophic stimuli contributes to the hypertrophic response by modulating the ERK and/or possibly the JNK (but not the p38-MAPK) cascades.

Regulation of protein kinase B and 4E-BP1 by oxidative stress in cardiac myocytes.

Stimulation of phosphatidylinositol 3'-kinase (PI3K) and protein kinase B (PKB) is implicated in the regulation of protein synthesis in various cells. One mechanism involves PI3K/PKB-dependent phosphorylation of 4E-BP1, which dissociates from eIF4E, allowing initiation of translation from the 7-methylGTP cap of mRNAs. We examined the effects of insulin and H(2)O(2) on this pathway in neonatal cardiac myocytes. Cardiac myocyte protein synthesis was increased by insulin, but was inhibited by H(2)O(2). PI3K inhibitors attenuated basal levels of protein synthesis and inhibited the insulin-induced increase in protein synthesis. Insulin or H(2)O(2) increased the phosphorylation (activation) of PKB through PI3K, but, whereas insulin induced a sustained response, the response to H(2)O(2) was transient. 4E-BP1 was phosphorylated in unstimulated cells, and 4E-BP1 phosphorylation was increased by insulin. H(2)O(2) stimulated dephosphorylation of 4E-BP1 by increasing protein phosphatase (PP1/PP2A) activity. This increased the association of 4E-BP1 with eIF4E, consistent with H(2)O(2) inhibition of protein synthesis. The effects of H(2)O(2) were sufficient to override the stimulation of protein synthesis and 4E-BP1 phosphorylation induced by insulin. These results indicate that PI3K and PKB are important regulators of protein synthesis in cardiac myocytes, but other factors, including phosphatase activity, modulate the overall response.

Phase I trial of alpha-tocopherol effects on 13-cis-retinoic acid toxicity.

BACKGROUND: Retinoids are under intensive study for the treatment and prevention of cancer. Substantial dose-related toxicities of retinoids are a major obstacle to this work. In a recent retrospective analysis of combined 13-cis-retinoic acid (13cRA) and alpha-tocopherol (AT) in myelodysplasia, 13cRA toxicity was reduced significantly and 13cRA activity was enhanced. These results suggested the need for prospective testing of this new combination. This trial tested the hypotheses that At can reduce toxicity of high-dose 13cRA and does not interfere with 13cRA absorption/activity as reflected by reduced 13cRA serum levels. PATIENTS AND METHODS: This was a phase I trial design in which patients received fixed-dose 13cRA (100 mg/m2/d) plus escalating-dose AT (beginning at 800 IU/d, increased 400 IU/d each month until 2000 IU/d). We collected toxicity data every four weeks from self-report forms, clinical examinations and laboratory studies. AT effects on 13cRA toxicity were determined by comparing maximum toxicity at lowest AT dose with that at highest AT dose. We also measured serum levels of both agents every four weeks. RESULTS: Of the 45 patients registered, 36 had cancer (active or prior history), 9 had premalignant lesions. Thirty-nine patients could be evaluated for initial-course toxicity; 31 for final course toxicity. Median time on treatment (all patients) was four months (range, 1-9 months); a total of 223 month-long courses of treatment were given. Eighteen percent of patients (7/39) developed grade 3 or 4 toxicity in the initial course. The rates of increase and decrease in 13cRA toxicity associated with increasing AT doses were similar: 36% decreased (11/31), 32% increased (10/31) (P = 0.84). At did not reduce 13cRA serum levels. After initial increases of mean AT plasma levels (17.9 micrograms/ ml at baseline to 45.4 micrograms/ml after first four-week course), subsequent AT plasma increases (< 2-fold) did not keep pace with increased AT doses (2-3-fold). No major activity occurred in the 21 patients with active refractory cancer. The complete response rate in patients with premalignant head-and-neck or lung lesions was 77.8% (7/9), which included two patients previously refractory to 13cRA alone. CONCLUSION: Although escalating doses of AT did not reduce 13cRA toxicity, the rate of initial-course (including 800 IU/d of AT) high-grade toxicity was substantially lower than that typical of high-dose 13cRA-alone and similar to that typical of low-dose 13cRA-alone. Indeed, a trial of 13cRA-alone followed by 13cRA plus AT may have detected a significant toxicity difference. We did not design such a trial out of ethical concern for known side effects of high-dose 13cRA. The increase in AT serum levels was not proportional with increasing doses of AT, which may explain the lack of a dose-response effect of AT on 13cRA toxicity. Previous trials have established that 13cRA has an approximate 10% complete response rate in oral premalignancy. Our small trial's 77.8% complete response rate in premalignant lesions suggests that AT may enhance 13cRA clinical activity. Future trials of 13cRA plus AT are needed to define this combinations toxicity profile, clinical activity and pharmacokinetics.

Insulin-like growth factor II and nonsuppressible insulin-like activity levels in newborns.

We measured insulin-like growth factor II and nonsuppressible insulin-like activity levels in the sera of newborn infants with different birth weights and gestational ages to determine the significance of these peptides in fetal growth. Our results obtained by use of one-way analysis of variance showed that the insulin-like growth factor II and nonsuppressible insulin-like activity levels in premature, average-weight-for-gestational-age, large-for-gestational-age, and small-for-gestational-age newborns were significantly different (p less than 0.01). Although levels in the premature neonates were less than the other three groups and large-for-gestational-age neonates had a higher insulin-like growth factor II level than the other three groups, maternal insulin-like growth factor II levels in all groups were similar. These results suggest that insulin-like growth factor II may play a major role in fetal growth.