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.

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