A multi-centre, double-blind, placebo-controlled, randomised trial of combination methotrexate and gefitinib versus methotrexate alone to treat tubal ectopic pregnancies (GEM3): trial protocol

Early (Days 1-4) post-treatment serum hCG level changes predict single-dose methotrexate treatment success in tubal ectopic pregnancy

STUDY QUESTION

What is the capacity of the change between Day 1 and Day 4 post-treatment serum human chorionic gonadotropin (hCG) levels for predicting single-dose methotrexate treatment success in tubal ectopic pregnancy?

SUMMARY ANSWER

Any fall in Days 1-4 serum hCG signified an 85% (95% CI 76.8-90.6) likelihood of treatment success for women with tubal ectopic pregnancy (initial hCG of ≥1000 and ≤5000 IU/l) managed with single-dose methotrexate.

WHAT IS KNOWN ALREADY

For those with tubal ectopic pregnancy managed by single-dose methotrexate, current guidelines advocate intervention if Days 4-7 hCG fails to fall by >15%. The trajectory of hCG over Days 1-4 has been proposed as an early indicator that predicts treatment success, allowing early reassurance for women. However, almost all prior studies of Days 1-4 hCG changes have been retrospective.

STUDY DESIGN, SIZE, DURATION

This was a prospective cohort study of women with tubal ectopic pregnancy (pre-treatment hCG of ≥1000 and ≤5000 IU/l) managed with single-dose methotrexate. The data were derived from a UK multicentre randomized controlled trial of methotrexate and gefitinib versus methotrexate and placebo for treatment of tubal ectopic pregnancy (GEM3). For this analysis, we include data from both treatment arms.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants were categorized according to single-dose methotrexate treatment success or failure. Treatment success for this analysis was defined as complete and uneventful resolution of tubal ectopic pregnancy to serum hCG <30 IU/l following single-dose methotrexate treatment without additional treatment. Patient characteristics of the treatment success and failure groups were compared. Changes in Days 1-4, 1-7, and 4-7 serum hCG were evaluated as predictors of treatment success through receiver operating characteristic curve analysis. Test performance characteristics were calculated for percentage change ranges and thresholds including optimal classification thresholds.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 322 women with tubal ectopic pregnancy were treated with single-dose methotrexate. The overall single-dose methotrexate treatment success rate was 59% (n = 189/322). For any fall in serum hCG on Days 1-4, likelihood ratios were >3, while for any fall of serum hCG >20% on Days 1-7, likelihood ratios reached 5. Any rise of serum hCG on Days 1-7 and 4-7 strongly reduced the chance of success. Any fall in Days 1-4 hCG predicted single-dose methotrexate treatment success with a sensitivity of 58% and specificity 84%, resulting in positive and negative predictive values of 85% and 57%, respectively. Any rise in Days 1-4 serum hCG <18% was identified as an optimal test threshold that predicted treatment success with 79% sensitivity and 74% specificity, resulting in 82% positive predictive value and 69% negative predictive value.

LIMITATIONS, REASONS FOR CAUTION

Our findings may be limited by intervention bias resulting from existing guidelines which influences evaluation of hCG changes reliant on Day 7 serum hCG levels.

WIDER IMPLICATIONS OF THE FINDINGS

Examining a large prospective cohort, we show the value of Days 1-4 serum hCG changes in predicting single-dose methotrexate treatment success in tubal ectopic pregnancy. We recommend that clinicians provide early reassurance to women who have a fall or only a modest (<18%) rise in Days 1-4 serum hCG levels, that their treatment will likely be effective.

STUDY FUNDING/COMPETING INTEREST(S)

This project was supported by funding from the Efficacy and Mechanism Evaluation programme, a Medical Research Council and National Institute for Health Research partnership (grant reference number 14/150/03). A.W.H. has received honoraria for consultancy for Ferring, Roche, Nordic Pharma and AbbVie. W.C.D. has received honoraria from Merck and Guerbet and research funding from Galvani Biosciences. L.H.R.W. has received research funding from Roche Diagnostics. B.W.M. is supported by a NHMRC Investigator grant (GNT1176437). B.W.M. also reports consultancy for ObsEva and Merck and travel support from Merck. The other authors declare no competing interests.

TRIAL REGISTRATION NUMBER

This study is a secondary analysis of the GEM3 trial (ISRCTN Registry ISRCTN67795930).

Have we overlooked the role of mifepristone for the medical management of tubal ectopic pregnancy?

Ectopic pregnancy is a risk of both spontaneous and assisted reproduction pregnancies. The majority of ectopic pregnancies abnormally implant within a fallopian tube (extrauterine pregnancies). In haemodynamically stable women, medical or expectant treatment can be offered. Currently accepted medical treatment is using a drug called methotrexate. However, methotrexate has potential adverse effects, and a significant proportion of women will still require emergency surgery (up to 30%) to remove the ectopic pregnancy. Mifepristone (RU-486) has anti-progesterone effects and has a role in managing intrauterine pregnancy loss and termination of pregnancy. On reviewing the literature and given progesterone's pivotal role in sustaining pregnancy, we propose that we may have overlooked the role of mifepristone in the medical management of tubal ectopic pregnancy in haemodynamically stable women.

Combination of gefitinib and methotrexate to treat tubal ectopic pregnancy (GEM3): a multicentre, randomised, double-blind, placebo-controlled trial

BACKGROUND

Tubal ectopic pregnancies can cause substantial morbidity or even death. Current treatment is with methotrexate or surgery. Methotrexate treatment fails in approximately 30% of women who subsequently require rescue surgery. Gefitinib, an epidermal growth factor receptor inhibitor, might improve the effects of methotrexate. We assessed the efficacy of oral gefitinib with methotrexate, versus methotrexate alone, to treat tubal ectopic pregnancy.

METHODS

We performed a multicentre, randomised, double-blind, placebo-controlled trial across 50 UK hospitals. Participants diagnosed with tubal ectopic pregnancy were administered a single dose of intramuscular methotrexate (50 mg/m2) and randomised (1:1 ratio) to 7 days of additional oral gefitinib (250 mg daily) or placebo. The primary outcome, analysed by intention to treat, was surgical intervention to resolve the ectopic pregnancy. Secondary outcomes included time to resolution of ectopic pregnancy and serious adverse events. This trial is registered at the ISRCTN registry, ISCRTN 67795930.

FINDINGS

Between Nov 2, 2016, and Oct 6, 2021, 328 participants were allocated to methotrexate and gefitinib (n=165) or methotrexate and placebo (n=163). Three participants in the placebo group withdrew. Surgical intervention occurred in 50 (30%) of 165 participants in the gefitinib group and in 47 (29%) of 160 participants in the placebo group (adjusted risk ratio 1·15, 95% CI 0·85 to 1·58; adjusted risk difference -0·01, 95% CI -0·10 to 0·09; p=0·37). Without surgical intervention, median time to resolution was 28·0 days in the gefitinib group and 28·0 days in the placebo group (subdistribution hazard ratio 1·03, 95% CI 0·75 to 1·40). Serious adverse events occurred in five (3%) of 165 participants in the gefitinib group and in six (4%) of 162 participants in the placebo group. Diarrhoea and rash were more common in the gefitinib group.

INTERPRETATION

In women with a tubal ectopic pregnancy, adding oral gefitinib to parenteral methotrexate does not offer clinical benefit over methotrexate and increases minor adverse reactions.

FUNDING

National Institute of Health Research.

Future Perspectives of Ectopic Pregnancy Treatment-Review of Possible Pharmacological Methods

Ectopic pregnancy, that is, a blastocyst occurring outside the endometrial cavity of the uterus, affects nearly 2% of pregnancies. The treatment of ectopic pregnancy is surgical or pharmacological. Since surgical management is associated with numerous serious side effects, conservative treatment is sought. The treatment of choice in the majority of cases is based on pharmacotherapy with methotrexate (MTX) in a single- or multi-dose regimen. Although the efficacy of methotrexate reaches between 70 and 90%, its use requires specific conditions regarding both the general condition of the patient and the characteristic features of the ectopic pregnancy. Moreover, MTX can cause severe adverse effects, including stomatitis, hepatotoxicity and myelosuppression. Therefore, clinicians and researchers are still looking for a less toxic, more effective treatment, which could prevent surgeries as a second-choice treatment. Some studies indicate that other substances might constitute a good alternative to methotrexate in the management of ectopic pregnancies. These substances include aromatase inhibitors, especially letrozole. Another promising substance in EP treatment is gefitinib, an inhibitor of EGFR tyrosine domain which, combined with MTX, seems to constitute a more effective alternative in the management of tubal ectopic pregnancies. Other substances for local administration include KCl and absolute ethanol. KCl injections used in combination with MTX may be used when foetal heart function is detected in cervical ectopic pregnancies, as well as in heterotopic pregnancy treatment. Absolute ethanol injections proved successful and safe in caesarean scar pregnancies management. Thus far, little is known about the use of those substances in the treatment of ectopic pregnancies, but already conducted studies seem to be promising.