First monkeypox patient treated with SIGA’s smallpox antiviral via expanded access

USA – The CDC has announced that one monkeypox patient in the US so far has been treated with SIGA Technologies’ tecovirimat, known commercially as TPOXX, which is an antiviral agent from the strategic national stockpile with anti-orthopoxvirus activity.

The antiviral is only currently licensed to treat smallpox, so the FDA and company made it available to CDC under an expanded access IND.

CDC also said it released smallpox vaccines — Emergent’s ACAM2000 and Bavarian Nordic’s Jynneos — to those at high-risk of exposure to monkeypox, either through contact with someone who has it, or certain intermediate risk exposures, such as being within ≤6 feet of an unmasked patient for ≥3 hours without wearing, at a minimum, a surgical mask.

But the CDC also warned that the post-exposure prophylaxis of the vaccine is not recommended for those at low or uncertain risk of monkeypox such as health care providers entering a patient’s room without eye protection.”

News of the first use of treatment and vaccines comes as the CDC says the outbreak of monkeypox, a zoonotic disease from a so-far unknown animal reservoir, is now in 9 states.

As of May 31, the CDC had identified 17 cases in the US, with 16 cases diagnosed in persons who identify as gay, bisexual, or men who have sex with men.


Fourteen of the 17 patients also reported international travel involving 11 different countries during the 21 days preceding symptom onset.

Currently, all patients are clinically well and being monitored by health authorities to determine the end of isolation (i.e., after all lesion scabs have fallen off, and new, healed skin has formed),” the agency said.

But CDC’s contact investigation is ongoing, as among the 13 patients who have identified contacts, there are 56 high-, 117 intermediate-, and 235 low- or uncertain-risk contacts.

“Contacts are recommended to be monitored for signs and symptoms consistent with monkeypox (e.g., fever, chills, lymphadenopathy, and rash) for 21 days following last exposure,” the CDC said in a report.

While the virus is endemic in several central and West African countries, the CDC said there are two clades of monkeypox virus, West African and Congo Basin, the latter causing more severe illness.

Since monkeypox reemerged in Nigeria in 2017, isolated cases have occurred outside Africa but they have been either people recently traveling to Nigeria or contacts of persons with travel-associated cases.

The UK, which is seeing its own surge of monkeypox cases too, is planning to commission a Phase 2 study to investigate the efficacy of tecoviramat for the management of monkeypox in a non-hospitalized population.

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