Use of M-M-R II outside of the routinely recommended age range - a systematic literature review

M-M-R®_II (M-M-R II) is routinely used in many countries at 12–15 months with a second dose at 4 to 6 years of age. However, the vaccine may need to be administered at other ages due to delays in the immunization schedule or in certain situations such as outbreaks or international travel. A systematic literature review was conducted to evaluate efficacy, immunogenicity and safety of M-M-R II among 6- to 11-month-olds and persons ≥7 years of age. A search for randomized controlled trials (RCTs) was conducted in 2019 including Medline, Embase and Cochrane CENTRAL. Only one study reported seroconversion rates after one dose in infants at 9 months of age: 87.4% (measles), 92.3% (mumps), and 91.2% (rubella); no safety data were reported. Seven studies reported immunogenicity and safety data for M-M-R II at ≥7 years of age. Seroconversion rates ranged from 96%-100% (measles), 65%-100% (mumps), and 91%-100% (rubella). Rates of selected adverse events ranged from 5.2%-8.7% for fever (≥38°C or ≥38.1°C), 2%-33.3% for injection site reactions, and 0.4% for measles/rubella-like rash (one study). No efficacy studies were found. This literature review identified RCTs with evidence to support that M-M-R II is immunogenic and well tolerated in individuals ≥7 years of age.

Summary of the HESI consortium studies exploring circulating inhibin B as a potential biomarker of testis damage in the rat

The Developmental and Reproductive Toxicity Technical Committee of the Health and Environmental Sciences Institute hosted a working consortium of companies to evaluate a new commercially available analytic assay for Inhibin B in rat serum or plasma. After demonstrating that the kit was stable and robust, the group performed a series of independent pathogenesis studies (23 different compound/investigator combinations) designed to examine the correlation between the appearance of lesions in the testis and changes in circulating levels of Inhibin B. These studies were reported individually in the previous articles in this series (this issue), and are discussed in this paper. For roughly half of these exposures, lesions appeared well before Inhibin B changed. A few of the studies showed a good correlation between seminiferous tubule damage and reduced circulating Inhibin B levels, while for seven exposures, circulating Inhibin B was reduced with no detectable alteration in testis histology. Whether this indicates a prodromal response or a false-positive signal will require further investigation. These exceptions could plausibly suggest some value of circulating Inhibin B as a useful biomarker in some circumstances. However, for roughly half of these exposures, Inhibin B appeared to be a lagging biomarker, requiring significant damage to the seminiferous tubules before a consistent and credible reduction in circulating levels of Inhibin B was observed.

Inhibin B response to testicular toxicants hexachlorophene, ethane dimethane sulfonate, di-(n-butyl)-phthalate, nitrofurazone, DL-ethionine, 17-alpha ethinylestradiol, 2,5-hexanedione, or carbendazim following short-term dosing in male rats

BACKGROUND

Inhibin B is a heterodimer glycoprotein that downregulates follicle-stimulating hormone and is produced predominantly by Sertoli cells. The potential correlation between changes in plasma Inhibin B and Sertoli cell toxicity was evaluated in male rats administered testicular toxicants in eight studies. Inhibin B fluctuations over 24 hr were also measured.

METHODS

Adult rats were administered one of eight testicular toxicants for 1 to 29 days. The toxicants were DL-ethionine, dibutyl phthalate, nitrofurazone, 2,5-hexanedione, 17-alpha ethinylestradiol, ethane dimethane sulfonate, hexachlorophene, and carbendazim. In a separate study plasma was collected throughout a 24-hr period via an automatic blood sampler.

RESULTS

Histomorphologic testicular findings included seminiferous tubule degeneration, round and elongate spermatid degeneration/necrosis, seminiferous tubule vacuolation, aspermatogenesis, and interstitial cell degeneration. There was a varying response of plasma Inhibin B levels to seminiferous tubule toxicity, with three studies showing high correlation, three studies with a response only at a certain time or dose, and two studies with no Inhibin B changes. In a receiver operating characteristics exclusion model analysis, where treated samples without histopathology were excluded, Inhibin B showed a sensitivity of 70% at 90% specificity in studies targeting seminiferous tubule toxicity.

CONCLUSION

Decreases in Inhibin B correlated with Sertoli cell toxicity in the majority of studies evaluated, demonstrating the value of Inhibin B as a potential biomarker of testicular toxicity. There was no correlation between decreases in Inhibin B and interstitial cell degeneration. In addition, a pattern of Inhibin B secretion could not be identified over 24 hr.