5511 - ASSERT: A Prospective, Observational Study Measuring Sodium Improvement and Outcomes in Patients Treated for Moderate to Severe Hyponatremia Secondary to Syndrome of Inappropriate Antidiuretic Hormone secretion (SIADH) in Italy (Lung Cancer Cohort)

Background

Hyponatremia (serum sodium concentration [Na+] <135 mmol/L), is the most common electrolyte disorder in lung cancer patients (incidence 20–44%) with SIADH a frequent cause, particularly in small cell lung cancer (SCLC).

Methods

ASSERT was a prospective, observational, non-interventional study conducted from October 2015 to June 2017 in cancer patients requiring treatment for hyponatremia secondary to SIADH at 18 Italian oncology centres. Management of hyponatremia primarily included water restriction, tolvaptan and hypertonic saline, in accordance with local standard of care/guideline recommendations. The primary endpoint was change in serum [Na+] from baseline visit to end of the first month of the observational period, or earlier discontinuation.

Results

The full analysis set (FAS) included 68 adult cancer patients (lung cancer, n = 48, SCLC, n = 33). Group 1 patients received ≥1 dose of tolvaptan during the observational period; Group 2 patients did not receive tolvaptan. Overall survival (FAS) was significantly higher in Group 1 vs Group 2 (median 123 vs 56 days; p = 0.001), as was mean survival (299.4 vs 74.9 days; p = 0.001). In a linear regression analysis of the relationship between sodium levels and tolvaptan dose intensity for the lung cancer and SCLC cohorts, dose intensity correlated significantly with clinical response after 6 months of treatment in both cohorts (p = 0.005 and p = 0.023, respectively). In the lung cancer cohort, a significantly higher percentage of patients achieved serum [Na+] ≥130 mmol/L in Group 1 vs Group 2 during 6 months of follow-up (Group 1, 87.5% vs Group 2, 62.5%; p = 0.033). These results were similar to those observed in the FAS.

Conclusions

Hyponatremia secondary to SIADH is a potentially modifiable risk factor, which might be implicated in the survival of lung cancer patients. Correction of hyponatremia may be preferentially achieved with pharmacological treatment, rather than the non-pharmacological approaches routinely used in clinical practice.

Clinical trial identification

NCT102573077.

Editorial acknowledgement

Sarah Stowell PhD, CMPP of Ashley Medical Communications, funded by Otsuka Pharmaceutical Europe Ltd.

Legal entity responsible for the study

Otsuka Pharmaceutical Italy Srl.

Funding

Otsuka Pharmaceutical Italy Srl.

Disclosure

R. Berardi: Honoraria (self), Advisory / Consultancy: Otsuka Pharmaceutical. C. Ferrara: Full / Part-time employment: Otsuka Pharmaceutical Italy. M.G. Giustra: Full / Part-time employment: Otsuka Pharmaceutical Italy. R. Evans: Full / Part-time employment: Otsuka Pharmaceutical Europe. All other authors have declared no conflicts of interest.