Dear Colleagues,

We would like to ask your opinion on two topics related to the pharmacological treatment of pregnant women with cancer.

Treating cancer during pregnancy presents a challenge for clinicians, as the risks and benefits of using chemotherapy or immunotherapy, along with co-medications (e.g. anti-emetics), must be carefully balanced. While the efficacy and toxicity of many medications have been established in non-pregnant women, there is a general lack of information regarding dosing regimens and the safety of these drugs in pregnancy.

Pregnancy induces physiological changes in the female body. For example, during pregnancy, there is a decrease in intestinal motility, an increase in gastric acidity, and an elevated glomerular filtration rate (GFR). These changes are likely to affect the pharmacokinetics (PK) of many drugs. The resulting alterations in PK could lead to supra- or subtherapeutic drug concentrations in the mother. Additionally, drug exposure might result in toxic concentrations in the fetus, as many drugs are actively or passively transported across the placenta. As a consequence, dosage adjustments may be necessary. Currently, pregnant women often receive the same doses as non-pregnant women. Understanding altered PK parameters and pharmacodynamics (efficacy and safety) during pregnancy allows evidence-based dosing regimens for this special population.

Physiologically based pharmacokinetic (PBPK) models may offer valuable guidance in this regard, as collecting PK data from prospective clinical trials is challenging, if not impossible, in this population.

A PBPK model is a mathematical framework that simulates drug concentrations in tissues over time, taking into account absorption, distribution across tissues and blood, metabolism, and excretion. It also considers the interactions between a patient’s physiological and biochemical characteristics and the physicochemical properties of the drug being studied.

Development and validation of a useful PBPK model requires significant effort. Therefore, we need to prioritize which drugs should be investigated based on current and future prescription 

Therefore, we like to ask you:

Question 1:
Which drugs have you used or advised to use during pregnancy? 

Question 2:
Which drugs require further research according to your opinion, as there is currently insufficient data to ensure safe treatment during pregnancy, despite their successful use in non-pregnant patients?

Answering these questions will take approximately 15-30 minutes depending on which types of cancer you treat or give advice on. We greatly appreciate your time and effort in completing this survey.

Fill in using Google Forms: Questionnaire concerning prescribing chemotherapy or immunotherapy to pregnant women (google.com)

With kind regards,
Dr. Christianne Lok, Gynecologic Oncologist
Dr. Paola Mian, Hospital Pharmacist/Clinical Pharmacologist
Drs. Wobbe Hospes, PhD Candidate