8,438,790 Shares of Common Stock2,200,000 Shares of Common Stock Issuable Upon Exercise of Pre-Funded Warrants5,319,392 Shares of Common Stock Issuable Upon Exercise of Milestone Warrants This prospectus relates to the resale by the selling stockholders named herein, including their transferees, assigns, pledgees ordonees, or their respective successors, of an aggregate of up to the following held by the selling stockholders: (i) 8,438,790 shares (the“Shares”) of our common stock, par value $0.0001 per share (which we refer to as our common stock), (ii) 2,200,000 shares (the“PFW Shares”) of our common stock issuable upon exercise of pre-funded warrants (the “Pre-Funded Warrants”) and (iii) 5,319,392shares (the “Milestone Warrant Shares”) of our common stock issuable upon the exercise of revenue milestone warrants (the“Milestone Warrants”). The Shares, Pre-Funded Warrants and Milestone Warrants were issued by us in a private placement whichclosed on March 20, 2026 (the “March 2026 Private Placement”). The selling stockholders listed herein were the investors in theMarch 2026 Private Placement. For information about the selling stockholders, see “Selling Stockholders.” We are not selling any securities under this prospectus and will not receive any of the proceeds from the sale of commonstock by the selling stockholder, although we may receive funds in the future upon the exercise of the Milestone Warrants held by theselling stockholders, if and when exercised for cash. The selling stockholders may sell Shares, PFW Shares and Milestone WarrantShares (collectively, the “Selling Stockholder Shares”) from time to time in the principal markets on which the common stock isquoted at the prevailing market price, at prices related to prevailing market prices or in negotiated transactions. The sellingstockholders may sell the Selling Stockholder Shares to or through underwriters, broker-dealers or agents, who may receivecompensation in the form of discounts, concessions or commissions from the selling stockholders, the purchasers of the SellingStockholder Shares, or both. We are registering the offer and sale of the Selling Stockholder Shares pursuant to certain registrationrights granted to the selling stockholders. The timing and amount of any sale of Selling Stockholder Shares is within the sole discretionof the selling stockholders. We do not know when or in what amount of Selling Stockholder Shares the selling stockholders may offerfor sale. We have paid the expenses of registering the Selling Stockholder Shares, including legal and accounting fees. All selling andother expenses incurred by the selling stockholders will be borne by the selling stockholders. See “Plan of Distribution” for additionalinformation. Our common stock is listed on The Nasdaq Capital Market under the symbol “RNXT.” On April 24, 2026, the last reportedsale price of our common stock on The Nasdaq Capital Market was $0.8566 per share. The purchase of the common stock offered through this prospectus is speculative and involves a high degree of risk.Youshould carefully consider the risk factors beginning on page 4 of this prospectus before purchasing any of the securities offeredby this prospectus. We may amend or supplement this prospectus from time to time by filing amendments or supplements as required.You should read the entire prospectus and any amendments or supplements carefully before you make your investmentdecision. Neither the Securities and Exchange Commission (“SEC”) nor any state securities commission has approved ordisapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contraryis a criminal offense. The date of this prospectus is April 27, 2026. TABLE OF CONTENTS PageAbout This ProspectusiiCautionary Note Regarding Forward-Looking StatementsiiiProspectus Summary1The Offering3Risk Factors4Use of Proceeds5Selling Stockholders6Plan of Distribution9Legal Matters11Experts11Where You Can Find More Information11Incorporation of Certain Information by Reference11 ABOUT THIS PROSPECTUS The information contained or incorporated by reference in this prospectus is not complete and may be changed. You shouldrely only on the information provided in or incorporated by reference in this prospectus, in any prospectus supplement or in a relatedfree writing prospectus, or documents to which we otherwise refer you. We have not authorized anyone else to provide you withdifferent information. We have not authorized any dealer, agent or other person to give any information or to make any representation other thanthose contained or incorporated by reference in this prospectus and any accompanying prospectus supplement or any related freewriting prospectus. You must not rely upon any information or representation not contained or incorporated by reference in thisprospectus or an accompanying prospectus supplement or any related free writing prospectus. This prospectus and any acc