Tenofovir did not increase the incidence nephrotoxicity in limited numbers of HIV-positive patients using chemotherapy or HCV-coinfeced patients using ribavirin

9 September 2006. Related: Conference reports, Side effects, Cancer and HIV, World AIDS 16 Toronto 2006.

Simon Collins, HIV i-Base

Two posters from the Chelsea and Westminster used their database of over 5,000 patients to look prospectively at patients using tenofovir in their ARV combination, who were also using potentially nephroptoxic chemotherapy for haematological malignancies, or retrospectively at HCV coinfected patients using ribavirin for HCV treatment.

Tenofovir was included in the regimen for 50/142 patients (35%) treated with anthracycline-based combination chemotherapy and concomitant HAART. [1]

At the start of chemotherapy, 8 (6%) had CTC grade 1-4 renal toxicity (elevated serum creatinine (Cr) >110 umol/L), including one patient on chronic haemodialysis. These included 3 patients on TDF and 5 not on TDF (p=0.93). The median peak serum Cr for these patients was 152 umol/lL(range 137-234), and did not differ between TDF group and non TDF group (p=0.48) During the course of chemotherapy, a further 9 patients developed renal impairment; 2/50 on TDF and 7/92 not on TDF (p=0.38). The median peak serum Cr in this group was 274umol/L (range 166-581), this was lower in the TDF group (median 176 umol/L, range 166-187) than the non-TDF group (median 277 umol/L, range 207-581) (Mann Whitney U p=0.04).

In the second analysis, 350 HIV/HCV coinfected patients with at least two recorded creatinine values of >120 umol/L were identified, of which had been exposed to tenofovir and/or ribavirin, and and creatine clearance was compared by treatment use. [2]

The prevalence of abnormal creatinine was 32.1 per 1000 patients (95% CI: 10.4 to 73.2) and 19.2 per 1000 patients (95% CI: 4.0-55.1) in patient exposed to either tenofovir or ribavirin respectively, and 12.8 per 1000 patients (95% CI: 1.5-45.6) in patients using both drugs,

Although these analysis do not comment on channelling bias (for example, treatment choice may have been affected in patients with any pre-existing renal concerns), it is important that no signal of increased toxicity were reported.

References:

1. Jones R, Low E, Nelson M et al. Tenofovir does not increase the incidence of chemotherapy related nephrotoxicity. Poster abstract TUPE0047.
2. Jones R, Bower M, Mandalia S et al. Renal toxicity in HIV/Hepatitis C co-infected individuals exposed to tenofovir and/or ribavarin. Poaster abstract CDB0734.