When Cat­a­lyst Phar­ma­ceu­ti­cals’ drug for Lam­bert-Eaton myas­thenic syn­drome (LEMS) — a rare, au­toim­mune dis­or­der that af­fects the con­nec­tion be­tween nerves and mus­cles — was ap­proved last year, car­ry­ing a $375,000 an­nu­al price tag, some pa­tients were not ex­act­ly thrilled. Hun­dreds of pa­tients had been able to ac­cess a sim­i­lar drug from com­pound­ing phar­ma­cies for a frac­tion of the cost, or from a small, fam­i­ly-run New Jer­sey-based com­pa­ny called Ja­cobus Phar­ma­ceu­ti­cals for free, as part of an FDA-rat­i­fied com­pas­sion­ate use pro­gram.

Once the Cat­a­lyst treat­ment, Fir­dapse, won ap­proval for adult LEMS pa­tients, it al­so won mar­ket ex­clu­siv­i­ty span­ning sev­en years — ef­fec­tive­ly pre­clud­ing Ja­cobus and com­pound­ing phar­ma­cies from sell­ing their ver­sions.

On Mon­day, how­ev­er, the FDA may have dis­rupt­ed that sta­tus quo by ap­prov­ing the Ja­cobus ver­sion for pa­tients aged 6 to 17, based on da­ta from a 32 adult pa­tient-study. The agency said it had used adult LEMS da­ta to de­duce a safe dos­ing reg­i­men for pe­di­atric pa­tients. As far as the FDA is con­cerned, doc­tors can pre­scribe drugs for un­ap­proved use, when they judge that it is med­ical­ly ap­pro­pri­ate for their pa­tient.

Shares of Coral Gables, Flori­da-based Cat­a­lyst $CPRX cratered af­ter-mar­ket on Mon­day. On Tues­day, the stock was down 36.5% at $3.88 be­fore the bell.

“The ap­proval of Ja­cobus’ Ruzur­gi for the treat­ment of pe­di­atric pa­tients with LEMS comes as a sur­prise, as in­vestors had all but writ­ten off this ver­sion of 3,4-DAP fol­low­ing Fir­dapse’s ap­proval (for adults, who com­prise near­ly all of the LEMS pop­u­la­tion) un­der the pre­sump­tion that oth­er forms would be blocked by or­phan ex­clu­siv­i­ty. With CPRX shares -43% af­ter Mon­day’s close, the mar­ket ap­pears to be fac­tor­ing sig­nif­i­cant im­pact to Fir­dapse’s com­mer­cial prospects from off-la­bel use of a (pre­sum­ably cheap­er) agent,” Op­pen­heimer an­a­lysts wrote in a note on Tues­day.

End­points News has con­tact­ed Ja­cobus for com­ment. De­pend­ing on how Ja­cobus prices its drug, Ruzur­gi — in­sur­ers could be per­suad­ed to fa­vor it over Cat­a­lyst’s prod­uct, de­spite the fact that it is of­fi­cial­ly ap­proved for on­ly pe­di­atric use.

Ac­cord­ing to a re­port by STAT, while Ja­cobus has not so far made a de­ci­sion on pric­ing, the own­er has sug­gest­ed that the com­pa­ny had spent $60 mil­lion on R&D and man­u­fac­tur­ing, and that post-ap­proval oblig­a­tions will like­ly cost the com­pa­ny an­oth­er $10 mil­lion to $20 mil­lion.

The Ruzur­gi for­mu­la­tion re­quires re­frig­er­a­tion — while the Fir­dapse for­mu­la­tion is sta­ble at room tem­per­a­ture, which gives Cat­a­lyst a slight ad­van­tage over Ja­cobus, Sun­Trust Robin­son Humphrey an­a­lyst Ed­ward Nash wrote in a note on Tues­day. “How­ev­er, the com­mer­cial po­ten­tial for Fir­dapse now would be de­pen­dent on rel­a­tive pric­ing as well as re­im­burse­ment cov­er­age”

In LEMS pa­tients, the body’s own im­mune sys­tem launch­es an at­tack on the neu­ro­mus­cu­lar junc­tion — which con­nects nerves and mus­cles. The con­di­tion can as­so­ci­at­ed with oth­er au­toim­mune dis­eases, but tends to oc­curs in pa­tients with can­cer. It’s preva­lence in pe­di­atric pa­tients is not known, but glob­al­ly it is es­ti­mat­ed to af­fect three per mil­lion in­di­vid­u­als, ac­cord­ing to the FDA.

Fir­dapse land­ed on the US mar­ket this Jan­u­ary, and in its fourth-quar­ter earn­ings call, Cat­a­lyst said the launch was off to a strong start, with man­age­ment not­ing min­i­mal push­back from pay­ers, and in­di­cat­ing that cov­ered pa­tients pay less than $10 per month out of pock­et.

Patrick McE­nany

But the com­pa­ny’s list price had al­ready trig­gered a tem­pest of crit­i­cism in pa­tient cir­cles and in Wash­ing­ton. Ver­mont Sen­a­tor Bernie Sanders — ahead of his an­nounce­ment to make a sec­ond at­tempt at the pres­i­den­cy — spot­light­ed Cat­a­lyst for “fleec­ing” tax­pay­ers and the “im­moral ex­ploita­tion of pa­tients,” un­der­scor­ing the is­sue as yet an­oth­er in­stance of a drug com­pa­ny’s “cor­po­rate greed.”

The FDA’s de­ci­sion on Ruzur­gi was like­ly in­flu­enced by pres­sure from Sanders, Sun­Trust’s Nash not­ed.

Cat­a­lyst chief Patrick McE­nany re­butted Sander’s as­ser­tions by say­ing the biotech had spent “mil­lions” test­ing the drug; that the com­pa­ny’s pric­ing pol­i­cy is in line with ul­tra-or­phan dis­eases of sim­i­lar sever­i­ty — and the firm is do­ing its ut­most to lim­it pa­tients’ out of pock­et cost; as well as down­played Ja­cobus’ free sup­ply, say­ing it was ben­e­fit­ting not more than a few hun­dred US pa­tients.

The com­pa­ny de­clined to com­ment on the Ja­cobus ap­proval.

Gilead is surging again off data that suggest its antiviral remdesivir might improve survival.

The new data come from an analysis Gilead conducted comparing the death rate and recovery time of patients in one of its remdesivir trials to a group of 800 patients “with similar baseline characteristics and disease severity” who received only standard-of-care around the same time. The result, they said, suggested that patients who received remdesivir had a 62% better chance at surviving than those who did not.

Many in the pharma world are hoping — better yet, expecting — JAK inhibitors to provide one of the next big boons for the industry. Few have invested as heavily in this area as Pfizer, which boasts a portfolio including Xeljanz and at least five mid-to-late stage candidates in the pipeline.

But a top Wall Street analyst is pumping the brakes on just how much good fortune is in store for the Big Pharma.