Association between immune checkpoint inhibitors and vascular endothelial growth factor targeted therapy with cardiovascular events

Background

The use of immune checkpoint inhibitors (ICI) has been associated with a 3-fold higher risk for cardiovascular events as compared to cancer patients who did not receive ICI. Therapies targeting vascular endothelial growth factor (VEGF) have also been associated with a wide range of cardiovascular events. The combination use of ICIs and VEGF inhibitors is currently approved as a treatment for patients with renal-cell carcinoma, hepatocellular carcinoma, non-small cell lung cancer, and endometrial cancer. Data are lacking whether the combination of ICIs and VEGF-targeted therapy is associated with an additional increase in cardiovascular events.

Purpose

To evaluate whether the combination use of ICI and VEGF targeted therapies are associated with a higher risk of cardiovascular events as compared to ICI therapy alone, we performed a retrospective matched case-control study.

Methods

Cases received both ICI and VEGF-targeted therapy (n=157), and control patients (n=157) only received ICI therapy. The primary outcome was a composite of cardiovascular events (myocardial infarction, coronary revascularization, ischemic stroke, deep venous thrombosis, and pulmonary embolism). Patients were censored at time of first event or at last date of follow up. Cox proportional hazard regression analysis was performed to calculate hazard ratio (HR) with 95% confidence interval (CI), counting only the first cardiovascular event.

Results

Baseline characteristics for the cases and controls are shown in Table 1. Overall cases (combination ICI and VEGF inhibitor) and controls (ICI alone) were not different with respect to age, type of cancer, and a prior history of any cardiovascular event. Cases received more ICI cycles as compared to controls (median of 7 [4–17] cycles vs. 4 [2–10] cycles, P<0.001). Cases also had a longer follow-up time (334 [127–663] days vs. 201 [60–564] days, P=0.008) as compared to the control group. As compared to ICI alone, a similar risk for a composite cardiovascular event was observed in those who received both ICI and VEGF-targeted therapy (HR, 0.70 [95% CI, 0.39–1.25]; P=0.23, Table 1). In total, 21/157 patients had a composite cardiovascular event among the cases, who received the combination of ICI and VEGF inhibitor (9 DVT, one MI, 9 PE, two ischemic strokes) as compared to 25/157 among the controls, who received ICI alone (14 DVT, 3 MI, 7 PE, one ischemic stroke). The median time to event was not different between the two groups (126 [98–260] days vs. 145 [28–205] days, P=0.47).

Conclusion

We found that among 157 patients who received a combination of ICI and VEGF-targeted therapy and 157 matched control patients who only received ICI therapy, the risk for cardiovascular events was not different between the two groups.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding.

Seeded growth of hydroxyapatite in the presence of dissolved albumin

Hydroxyapatite (HAP) crystals were grown from a supersaturated solution by the addition of a suspension of seed crystals at a controlled pH value of 7.4 and a temperature of 37 degrees C. The degree of supersaturation was comparable to that in biological fluids and was such that all HAP precipitated would be expected to deposit on the seeds. Albumin was added to some of the solutions to give a concentration in the range 75-250 micrograms cm-3. Samples of solution were removed at known times after the addition of seed crystals and their calcium ion concentrations were determined by atomic absorption spectroscopy. The decrease in the dissolved calcium concentration was taken to be a measure of crystal growth. In the absence of seeds, no decrease in calcium concentration occurred. The initial rate of HAP growth decreased linearly with albumin concentration, i.e., albumin was found to inhibit crystal growth. Inhibition kinetics were consistent with a Langmuir model in which a single albumin molecule was capable of binding to more than one growth site on the crystal surface. Comparison with published results indicated that albumin was a less potent inhibitor of HAP growth than phosphoproteins but was a more potent inhibitor than magnesium or citrate ions.

Seeded growth of hydroxyapatite in the presence of dissolved albumin at constant composition

Hydroxyapatite (HAP) crystals were grown from a supersaturated solution by the addition of seed crystals at a temperature of 37 degrees C. Throughout the experiment, the pH and calcium ion concentration were monitored by electrodes in the solution, and maintained at constant values by the addition of ammonia solution (maintaining a pH value of 7.4 during HAP precipitation) and calcium nitrate solution. Triammonium orthophosphate solution was added at the same time as calcium nitrate, so that the ratio of calcium to phosphate ions in the solution was appropriate to the precipitation of HAP. The volume of calcium nitrate solution which needed to be added was used as a measure of HAP crystal growth. Albumin was added to some of the supersaturated solutions to give a concentration in the range 50-250 micrograms cm-3. HAP crystals grown at different albumin concentrations were examined by scanning electron microscopy. After an initial period of 30 min, the growth of HAP crystals increased linearly with time. This behavior was attributed to initial growth healing such dislocations as steps and kinks; growth at screw dislocations was considered to occur throughout the period of the experiment and to give rise to the linear growth phase. The linear growth rate decreased linearly with the albumin concentration. HAP crystals grown in the absence of albumin formed spherical aggregates; the size of these aggregates decreased with the albumin concentration.

Agonist versus antagonist binding to alpha-adrenergic receptors

The binding properties of two alpha-adrenergic radioligands, [3H]epinephrine (an agonist) and [3H]dihydroergocryptine (an antagonist), were compared in two model systems--membranes derived from human platelets and membranes from rat liver. The platelet contains exclusively alpha 2 and the liver mostly (approximately 80%) alpha 1 receptors. Agonists induce the formation of a guanine nucleotide-sensitive high-affinity state of alpha 2 but not alpha 1 receptors. [3H]Dihydroergocryptine labels all the alpha receptors, whereas [3H]epinephrine at low concentrations labels predominantly the high-affinity form of the alpha 2 receptor in both platelet and liver. However, in the liver, alpha-adrenergic effects such as glycogen phosphorylase activation are shown to be mediated via alpha 1 receptors. Thus, in liver membranes the endogenous "physiological" agonist may not label the physiologically relevant alpha 1 receptors in typical radioligand binding assays using low concentrations of [3H]epinephrine.