Pembrolizumab for advanced melanoma: experience from the Spanish Expanded Access Program

Background. The programmed death (PD-1) inhibitor pembrolizumab has been recently approved for the treatment of advanced melanoma. We evaluated the clinical activity of pembrolizumab in melanoma patients treated under the Spanish Expanded Access Program. Methods. Advanced melanoma patients who failed to previous treatment lines were treated with pembrolizumab 2 mg/kg every three weeks. Patients with brain metastases were not excluded if they were asymptomatic. Data were retrospectively collected from 21 centers in the Spanish Melanoma Group. Results. Sixty-seven advanced melanoma patients were analyzed. Most patients were stage M1c (73.1%), had high LDH levels (55.2%) and had ECOG PS 1 or higher (59.7%). For cutaneous melanoma patients, median overall survival was 14.0 months; the 18-month overall survival rate was 47.1%. Overall response rate was 27%, including three patients with complete responses (6.5%). Median response duration was not reached, with 83.3% of responses ongoing (3.5 m+ to 20.4 m+). From ten patients included with brain metastases, four (40%) had an objective response, two (20%) of them achieved a complete response. Significant prognostic factors for overall survival were LDH level, ECOG PS and objective response. There were no serious adverse events. Conclusion. Although this was a heavily pretreated cohort, pembrolizumab activity at the approved dose and schedule was confirmed in the clinical setting with long-term responders, also including patients with brain metastases (AU)

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Pembrolizumab for advanced melanoma: experience from the Spanish Expanded Access Program.

BACKGROUND: The programmed death (PD-1) inhibitor pembrolizumab has been recently approved for the treatment of advanced melanoma. We evaluated the clinical activity of pembrolizumab in melanoma patients treated under the Spanish Expanded Access Program. METHODS: Advanced melanoma patients who failed to previous treatment lines were treated with pembrolizumab 2 mg/kg every three weeks. Patients with brain metastases were not excluded if they were asymptomatic. Data were retrospectively collected from 21 centers in the Spanish Melanoma Group. RESULTS: Sixty-seven advanced melanoma patients were analyzed. Most patients were stage M1c (73.1%), had high LDH levels (55.2%) and had ECOG PS 1 or higher (59.7%). For cutaneous melanoma patients, median overall survival was 14.0 months; the 18-month overall survival rate was 47.1%. Overall response rate was 27%, including three patients with complete responses (6.5%). Median response duration was not reached, with 83.3% of responses ongoing (3.5 m+ to 20.4 m+). From ten patients included with brain metastases, four (40%) had an objective response, two (20%) of them achieved a complete response. Significant prognostic factors for overall survival were LDH level, ECOG PS and objective response. There were no serious adverse events. CONCLUSION: Although this was a heavily pretreated cohort, pembrolizumab activity at the approved dose and schedule was confirmed in the clinical setting with long-term responders, also including patients with brain metastases.

Potassium transmembrane fluxes in anoxic hepatocytes from goldfish (Carassius auratus L.).

Despite the fact that anoxic goldfish hepatocytes can maintain the transmembrane gradients of Na(+), H(+) and Ca(2+), cyanide (CN) intoxication leads to a rapid breakdown of K(+) homeostasis. In this study, [(86)Rb(+)] K(+) fluxes across the plasma membrane of goldfish hepatocytes were studied in order to identify the possible causes of this imbalance. Four minutes of cyanide incubation induced an acute and stable 61% decrease of K(+) influx (mostly driven by Na,K-ATPase activity), whereas K(+) efflux increased by 24.3%, this imbalance yielding a net K(+) efflux of 0.279+/-0.024 nmol 10(-6) cells(-1) min(-1). This uncoupling was not observed when glycolytic ATP production was inhibited with iodoacetic acid. Although the CN-induced decrease of K(+) influx was fully reversible upon washout of the inhibitor, it could not be prevented by any of the following treatments: (1) addition of 2% bovine serum albumin, which binds extracellular fatty acids known to activate specific K(+) channels; (2) addition of ascorbate, which acts as a radical scavenger; (3) inclusion of 5 mM glucose as an extracellular carbon source; and (4) removal of medium oxygen (obtained by nitrogen bubbling). Regarding the elevation of K(+) efflux in the presence of CN, neither ATP-dependent K(+) channels nor the KCl cotransporter appeared to be activated, whereas BaCl(2), an inhibitor of voltage-gated K(+) channels, decreased K(+) efflux of CN-intoxicated cells to control levels. In summary, these results indicate that, in goldfish hepatocytes, the CN-induced K(+) imbalance results from acute Na,K-ATPase inhibition together with the activation of voltage-dependent K(+) channels, the latter probably resulting from transient membrane depolarization.

Effects of extracellular nucleotides and their hydrolysis products on regulatory volume decrease of trout hepatocytes.

In trout hepatocytes, hypotonic swelling is followed by a compensatory shrinkage called regulatory volume decrease (RVD). It has been postulated that extracellular ATP and other nucleotides may interact with type 2 receptors (P(2)) to modulate this response. In addition, specific ectoenzymes hydrolyze ATP sequentially down to adenosine, which may bind to type 1 receptors (P(1)) and also influence RVD. Accordingly, in this study, we assessed the role of extracellular nucleoside 5'-tri- and diphosphates and of adenosine on RVD of trout hepatocytes. The extent of RVD after 40 min of maximum swelling was denoted as RVD(40), whereas the initial rate of RVD was called v(RVD). In the presence of hypotonic medium (60% of isotonic), hepatocytes swelled 1.6 times followed by v(RVD) of 1.7 min(-1) and RVD(40) of 60.2%. ATP, UTP, UDP, or ATPgammaS (P(2) agonists; 5 microM) increased v(RVD) 1.5-2 times, whereas no changes were observed in the values of RVD(40). Addition of 100 microM suramin or cibacron blue (P(2) antagonists) to the hypotonic medium produced no effect on v(RVD) but a 53-58% inhibition of RVD(40). Incubation of hepatocytes in the presence of either 5 microM [gamma-(32)P]ATP or [alpha-(32)P]ATP induced the extracellular release of [gamma-(32)P]P(i) (0.21 nmol.10(-6) cells(-1).min(-1)) and [alpha-(32)P]P(i) ( approximately 8 x 10(-3) nmol.10(-6) cells(-1).min(-1)), suggesting the presence of ectoenzymes capable of fully dephosphorylating ATP. Concerning the effect of P(1) activation on RVD, 5 microM adenosine, both in the presence and absence of 100 microM S-(4-nitrobenzil)-6-tioinosine (a blocker of adenosine uptake), decreased RVD(40) by 37-44%, whereas 8-phenyl theophylline, a P(1) antagonist, increased RVD(40) by 15%. Overall, results indicate that ATP, UTP, and UDP, acting via P(2), are important factors promoting RVD of trout hepatocytes, whereas adenosine binding to P(1) inhibits this process.

Volumetric and ionic responses of goldfish hepatocytes to anisotonic exposure and energetic limitation.

The relationship between cell volume and K(+) transmembrane fluxes of goldfish (Carassius auratus) hepatocytes exposed to anisotonic conditions or energetic limitation was studied and compared with the response of hepatocytes from trout (Oncorhynchus mykiss) and rat (Rattus rattus). Cell volume was studied by video- and fluorescence microscopy, while K(+) fluxes were assessed by measuring unidirectional (86)Rb(+) fluxes. In trout and rat hepatocytes, hyposmotic (180 mosmoll(-1)) exposure at pH 7.45 caused cell swelling followed by a regulatory volume decrease (RVD), a response reported to be mediated by net efflux of KCl and osmotically obliged water. By contrast, goldfish hepatocytes swelled but showed no RVD under these conditions. Although in goldfish hepatocytes a net ((86)Rb(+))K(+) efflux could be activated by N-ethylmaleimide, this flux was not, or only partially, activated by hyposmotic swelling (120-180 mosmoll(-1)). Blockage of glycolysis by iodoacetic acid (IAA) did not alter cell volume in goldfish hepatocytes, whereas in the presence of cyanide (CN(-)), an inhibitor of oxidative phosphorylation, or CN(-) plus IAA (CN(-)+IAA), cell volume decreased by 3-7%. Although in goldfish hepatocytes, energetic limitation had no effect on ((86)Rb(+))K(+) efflux, ((86)Rb(+))K(+) influx decreased by 57-66% in the presence of CN(-) and CN(-)+IAA but was not significantly altered by IAA alone. Intracellular K(+) loss after 20 min of exposure to CN(-) and CN(-)+IAA amounted to only 3% of the total intracellular K(+). Collectively, these observations suggest that goldfish hepatocytes, unlike hepatocytes of anoxia-intolerant species, avoid a decoupling of transmembrane K(+) fluxes in response to an osmotic challenge. This may underlie both the inability of swollen cells to undergo RVD but also the capability of anoxic cells to maintain intracellular K(+) concentrations that are almost unaltered, thereby prolonging cell survival.