Pembrolizumab 21 days cycle queries - 1290382

Thu, 03/16/2017 - 03:45

Hi, my father had NSCLC with plureal effusion, he just started 1st cycle of pembrolizumab... Due to my working schedule I would like to check if it is possible to delay the 2nd cycle from 21 days to 23? Will the 2 days delay make different in his treatment? Or it has to follow the 21 days cycle? Thanks alot for your kind assist.

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Hi narret,

There's nothing particularly special about the typical 21 day cycle as opposed to 23 days, except that most cancer treatments are given Monday through Friday, and if you consistently use a 23 day interval, that would be a problem. But if it's just a one-time or occasional adjustment, your cancer center may be willing to work with you. It can't hurt to ask.

It would be more of a problem if you wanted to shorten the cycle, since the 21 day period tends to represent the time it takes for a patient's blood counts and general well-being to rebound after the previous treatment.

Good luck to your dad with pembrolizumab.

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Hi narret and welcome to Grace.

This isn't an answer that can be given with certainty. But what most oncologists would say is it probably won't make a difference. The truth is the 21 day cycle was chosen (certainly in part because it's a multiple of 7 and fits nicely into most schedules) and studied and those are the data we know and go by. 23 day intervals haven't been studied so no one can say for sure those results are the same. With that said it's not unusual to change infusion dates because of schedule or health issues without discernible changes in outcomes. If it's necessary to accompany him then 23 days is what it is.

With chemotherapy schedules can become quite loose, skipping a week for blood levels to even out, for holiday, or special trips. In my husband's case to let blood levels even out one of his treatment regimens was given every 3rd week instead of 2nd. We were both more than happy for that.

With the TKI tarceva many changes are made in dosing; depending on an individual's side effects dosing can go from 150mg down to 25.

Immunotherapies are so new we don't have case studies to point to to say we do it all the time but I imagine there will be. I'm guessing this isn't really an issue with the oncologist unless it's a scheduling issue. Yes?

I hope that helps to put your mind at ease.
All best,

Posts: 7

Dear JimC and catdander, thanks a lot for your input, its a one time adjustment i wish to make so 3rd cycle onward will surely go back to 21 days cycle. Thanks again for your precious comment, will proceed on 23 days for 2nd cycle. Thanks.