There’s no more icon­ic shape in bi­ol­o­gy than the twist­ing strands of DNA. Yet that same dou­ble he­lix that makes the mol­e­cule in­stant­ly rec­og­niz­able may al­so be the very thing hold­ing back cheap­er, safer, and more ef­fec­tive forms of gene ther­a­py, ac­cord­ing to new re­search.

But for­eign DNA used as a treat­ment can al­so trig­ger the in­nate im­mune sys­tem’s alarm bells, an in­sur­mount­able hur­dle for sci­en­tists try­ing to de­vel­op gene ther­a­pies that don’t re­ly on en­gi­neered virus­es, which have their own cost, safe­ty and ef­fi­ca­cy is­sues.

A new study pub­lished Wednes­day in Na­ture adds weight to an emerg­ing idea that sim­ply us­ing a sin­gle-strand­ed form of DNA can help it slide past im­mune sen­sors when pack­aged in lipid nanopar­ti­cles — the most pop­u­lar non-vi­ral de­liv­ery ves­sel.

A hand­ful of biotech star­tups have re­cent­ly tak­en an in­creas­ing­ly pop­u­lar route of fi­nanc­ing: ex­tend­ing ex­ist­ing rounds rather than tak­ing on a whole new fundrais­ing cam­paign.

If "mon­ey is like oxy­gen for biotechs," in the words of Alveus CEO Raj Kan­nan, fund­ing-round top-ups are a faster, eas­i­er way to catch a quick breath.

Kan­nan's Alveus is one of at least four biotechs that have bol­stered their ex­ist­ing rounds so far this year. The obe­si­ty biotech is joined by blood-fo­cused Atavis­tik Bio, Xo­lair hunter Poplar Ther­a­peu­tics and move­ment dis­or­der biotech Vi­ma Ther­a­peu­tics. Those four ex­ten­sions have cor­ralled $162 mil­lion col­lec­tive­ly, or $552 mil­lion when fac­tor­ing in the ini­tial clos­es of those rounds.

Com­pound­ed forms of the mol­e­cule be­hind Eli Lil­ly’s meta­bol­ic block­busters Moun­jaro and Zep­bound that have vi­t­a­min B12 added to them may be un­safe, Lil­ly said Thurs­day.

Lil­ly and its fel­low GLP-1-based drug­mak­er No­vo Nordisk have both tak­en a stance against com­pound­ing phar­ma­cies, which make copy­cats of their drugs that some­times in­clude oth­er mol­e­cules such as vi­t­a­min B12 to dif­fer­en­ti­ate them from the brand­ed ver­sions. Lil­ly has sued com­pounders in the past, as has No­vo.

Lil­ly re­leased a warn­ing let­ter say­ing that tests had re­vealed “sig­nif­i­cant lev­els of an im­pu­ri­ty that re­sults from a chem­i­cal re­ac­tion be­tween tirzepatide and B12.” It sug­gest­ed that this im­pu­ri­ty could pose risks, in­clud­ing tox­i­c­i­ty and im­mune re­ac­tions, and added that pa­tients tak­ing these prod­ucts should seek al­ter­na­tive treat­ments.