There have been reports of a high rate of virological failure and of emergence of resistance at an early stage when lamivudine was combined with tenofovir disoproxil fumarate and abacavir as well as with tenofovir disoproxil fumarate and didanosine as a once daily regimen.
Epivir Summary of Product Characteristics, ViiV Healthcare UK Ltd, February 2019.

There were no clinically significant pharmacokinetic interactions when tenofovir disoproxil fumarate was coadministered with lamivudine.
Triple NRTI Therapy:
There have been reports of a high rate of virological failure and of emergence of resistance at early stage when tenofovir disoproxil fumarate was combined with lamivudine and abacavir as well as with lamivudine and didanosine as a once daily regimen.
Viread Summary of Product Characteristics, Gilead Sciences Ltd, September 2016.

Coadministration of tenofovir-DF (300 mg once daily) and lamivudine (150 mg twice daily for 7 days) was studied in 15 HIV-negative subjects. There was no change in tenofovir pharmacokinetic parameters. Lamivudine AUC and Cmin were unaltered, and there was a 24% decrease in Cmax.
Viread Prescribing Information, Gilead Sciences International Inc, February 2016.