Sunday, January 28, 2018

Topic Discussion: Gemcitabine induced TMA- what to do?

Thrombotic microangiopathy (TMA) can come in many forms- HUS and TTP might being the two most extreme versions. Gemcitabine induced TMA is a drug induced TMA that can result from dose dependent use of the agent or an immune mediated phenomenon.

In immune-mediated TMA, the drug induces formation of antibodies that react with multiple cells, including platelets, neutrophils, and endothelial cells, but strong binding only occurs in the presence of the drug (or drug metabolite). Therefore, these antibodies are described as drug-dependent antibodies. Toxicity-mediated (ie, non-antibody-mediated) TMA may develop by multiple mechanisms. Many cases are dose related, occurring only after large cumulative exposure over a period of time or exposure to large single doses of a drug. Gemcitabine induced TMA is thought to be due to both the above mechanisms.

Recent review found that of 78 substances to have previously been reported to cause thrombotic microangiopathy (TMA), 22 had definite evidence supporting causal association. However, 9 (clopidogrel, cyclosporine, estrogen/progesterone, gemcitabine, interferon, mitomycin, quinine, tacrolimus, and ticlopidine) accounted for 76% of reports.

Initial management involves immediate discontinuation of suspected drug, or reduction of dose when discontinuation is not a medical option.

What about pheresis or anti complement therapy specifically for Gemcitabine induced TMA?

A twitter pole I did showed these results

Here is the summary from the Pheresis society guidelines

In all cases of Gemcitabine induced TMA, ADAMTS13 levels were typically normal. In literature review, among 26 patients not treated with pheresis, 56% recovered from TMA, whereas 30% of 18 patients who received TPE. So based on that data, doubt pheresis will help TMA associated with gemcitabine.

There have been reports of patients with toxicity-mediated DITMA attributed to gemcitabine, case reports have described patients with acute kidney injury attributed to gemcitabine who improved after treatment with anti-complement therapy. However, these case reports do not provide confidence that anti-complement therapy is appropriate. Often the patients have received multiple chemotherapeutic agents, and the selection of gemcitabine as the possible cause-effect cannot be confirmed.

Often a kidney biopsy to document TMA has not been done. Although these preliminary observations do not provide confidence that anticomplement therapy is appropriate, some experts do feel it might be reasonable to consider the use of eculizumab in persistent drug toxicity-mediated TMA that does not improve with supportive care and withdrawal of the offending agent and especially if there is risk for progressive CKD.

So in summary

1. Most important- stop the offending agent
2. Data on use of pheresis- poor and in some instances might be not recommended
3. Data on use of complement inhibitor- poor and unclear at this point- probably would avoid but there might be mixed opinion on this matter in the literature.

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