Meaning of "D1 q3w" in a poster to a clinical trial

Question

From a poster to a clinical trial:

I can understand that q3w means "once every 3 weeks", but what is the meaning of D1? I think the first DI must be a typo and it stands for D1 too.

Answer 1

D1 means on day one of the three weekly cycles. DI is a typo.

https://oncologypro.esmo.org/meeting-resources/esmo-2016/Lurbinectedin-PM01183-administered-once-D1-every-3-weeks-q3w-in-combination-with-capecitabine-XEL-in-patients-pts-with-metastatic-breast-MBC-colorectal-CRC-or-pancreatic-PaC-cancer

Answer 2

DI stands for diachronic:

Diachronic: Over a period of time. The opposite of synchronic.

This would indicate that the medication is given in a drip, not as a bolus.

D1 seems to not have any standard meaning, the conclusion this answerer draws is that D1 is a probable transcription substitution for DI.