P6. Treatment outcomes among 74 HIV-1 infected patients treated with Stribild at Venhälsan.

Sam Sorial1, Göran Bratt1, Anders Blaxhult1, Catharina Maijgren Steffensson2, Lena Lindborg1

Affiliates: 1Venhälsan/Department of infectious diseases, Södersjukhuset, Stockholm, Sweden, 2Gilead Sciences Sweden, Solna, Sweden.

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Background
Stribild (STB) is the first integrase inhibitor-based single tablet regimen (STR) and consists of tenofovir, emtricitabine, elvitegravir and cobicistat.

Methods
This study includes 74 patients with a median age of 44 who were started on STB between June 2013 and December 2015 at Venhälsan. 27% were naive and 73% were treatment experienced. Among the naive patients, the median HIV-1 RNA viral load (VL) was 107234 copies/ml and the median nadir CD4s T-cell count was 398 cells/µl. In the experienced patients, the main reason for switching to STB was to simplify treatment. 4 patients had VL >500 cop/ml before switching, 8 had nadir CD4 <200 cells/µl and 3 had previously been diagnosed with AIDS. Previous anti-retroviral treatments (ARTs) included PIs in 50%, NNRTIs in 36% and INIs in 14% of the patients, whereas 93% of the ARTs included NRTI.

The data was collected retrospectively from the National Quality Register InfCareHIV and the patients´ files at Venhälsan according to local ethics committee advice. The effects of STB on the kidneys and serum lipids were assessed by: serum creatinine (SeCr), cystatin-C-calculated GFR (cysGFR), urine protein HC/creatinine ratio (uPCR), triglycerides, total cholesterol, LDL, HDL. Statistical significance was assessed by comparing the means before and after starting STB-treatment using paired T-tests.

Results
The median duration of STB in this cohort was 18 months (7-23 months). Among the naive patients, 3/20 (15%) discontinued STB due to virologic failure, renal and gastro-intestinal side effects, respectively, while 85% remained virologically suppressed. CD4 increased from 464 cells/µl before starting treatment to 746 cells/µl.

Among the 54 experienced patients, who switched ART, 44 (81.5%) remained virologically suppressed, whereas 10 discontinued STB (6 had side-effects/drug interactions, 3 virologic failures and 1 was upon patient request). The most common side-effect was GI upset and diarrhea. Other side-effects included anxiety, parasthesia, headache and drowsiness.
The differences in renal parameters were evaluated after 12 +/-5 months. Among the naive patients, cystGFR increased from 88 +/-3 to 90 +/- 1 ml/min/1.7 (p = 0.019) and SeCr increased from 77 to 89 +/-8 µmol/L (p = 0.003), while uPCR was unchanged. In the experienced patients, uPCR increased from 1.0 +/- 1.1 to 1.8 +/- 1.9 mg/mmol (p = 0.002) and there was a trend to increase in SeCr from 79 +/- 14 to 84 +/- 21 µmol/L (p = 0.066), while cysGFR was unchanged.
Evaluation of change in serum lipids after 7 +/-5 months no significant effects of STR on lipid parameters in naive patients. Among the experienced patients, there was a trend towards a decrease in total cholesterol from 4.9 +/- 1.8 to 4.4 +/- 1.7 mmol/L (p = 0.066).

Conclusion
This cohort consists mostly of 40-50 year old MSM who switched from NRTI + PI to STB for simplification. After an average of 18 months, 82% of the patients remained with viral suppression. The main reasons for discontinuing STB were GI side-effects or drug-drug interactions. The increase in SeCr seen in naive patients is a well-known cobicistat effect, whereas the increase in uPCR in the experienced patients could indicate a tenofovir-induced tubular toxicity. Moreover, STB may have a modest cholesterol-reducing effect in experienced patients. In conclusion, STB is well tolerated and is an effective alternative in both naive and experienced patients.