Bragar Eagel & Squire, P.C., a nationally recognized stockholder rights law firm, announces that a class action lawsuit has been filed against Y-mAbs Therapeutics, Inc. (“Y-mAbs” or the “Company”) (NASDAQ: YMAB) in the United States District Court for the Southern District of New York on behalf of all persons and entities who purchased or otherwise acquired Y-mAbs securities between October 6, 2020 and October 28, 2022, both dates inclusive (the “Class Period”). Investors have until March 20, 2023 to apply to the Court to be appointed as lead plaintiff in the lawsuit.

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According to Y-mAbs’s Form 10-K for fiscal 2021 (at 4), filed with the SEC on March 1, 2022, Y-mAbs is “a biopharmaceutical company focused on the development and commercialization of novel, antibody-based therapeutic products for the treatment of cancer.”

According to Y-mAbs’s public statements, “Omburtamab, our lead product candidate, is a murine monoclonal antibody that targets B7-H3, an immune checkpoint molecule that is widely expressed in tumor cells of several cancer types. 131 I-omburtamab, which is omburtamab radiolabeled with Iodine-131, is currently being studied in several clinical trials including pivotal stage development Study 101 and Study 03-133 for the treatment of pediatric patients who have CNS/LM from NB.” 2021 Form 10-K at 7.1

Study 03-133 included pediatric patients with neuroblastoma (NB) that relapsed in the central nervous system (CNS) or leptomeninges (CNS/LM).

Leptomeningeal metastases occurs when cancer cells have spread to thin layers of tissue that cover the brain and spinal cord.

According to Y-mAbs’s 2021 Form 10-K (at 27), there are approximately 700 children diagnosed with neuroblastoma (NB) in the United States each year. Of those, approximately 50-60% are high-risk, and of those at high-risk who relapse, Y-mAbs believes approximately 20% will suffer from leptomeningeal (central nervous system) metastases from neuroblastoma.

One treatment cycle of omburtamab takes 4 weeks and includes a treatment dose during week one followed by a 3-week observation period including a repeated MRI, CSF cytology, and safety monitoring.

Y-mAbs sought FDA approval of omburtamab through a Biologics License Application first in 2020 and again in 2022, based on a comparison between Study 03-133 performed at Memorial Sloan Kettering Cancer Center (“MSKCC”) and an external cohort comprising data from the Central German Childhood Cancer Registry, or CGCCR, database.

The efficacy population in Study 03-133 consisted of a subset of 94 patients ages 0.9 to 13 years. The first patient was enrolled in 2004, and the last patient enrolled in 2018.

Study 03-133 was a single-arm study without a control group.

The primary endpoint was overall survival (OS) at 3 years.

Tumor responses were not systematically analyzed in this study.

After CNS/LM relapse and prior to receiving omburtamab, all patients received at least one type of CNS-directed therapy (surgery, chemotherapy, and/or radiotherapy) and the majority of patients (76%) received all three treatment modalities.

The 3-year OS rate after CNS/LM relapse in the efficacy population of 94 patients was 54%.

The external control group (CGCCR), against which Study 03-133 was compared, included clinical data from patients with Stage 4 neuroblastoma included in the German national neuroblastoma clinical trials NB90, NB97 and NB2004 from 1990 to 2015.

Y-mAbs identified 79 patients in the source population who received at least one type of post-CNS relapse treatment (radiotherapy, chemotherapy, or surgery).

According to the 2021 Form 10-K “Data from 85 patients sourced from The Central German Childhood Cancer Registry, or CGCCR, showed a median OS of 4.7 months.” 2021 Form 10-K at 28.

Y-mAbs has represented in Form 10-K filings with the SEC that “An analysis of 107 patients with pediatric CNS/LM from NB who were treated with 131 I-Omburtamab in Study 03-133 demonstrated a median overall survival, or OS, of 50.8 months, as compared to historical median OS of approximately six to nine months.” 2021 Form 10-K at 7.

Study 101 is an ongoing international multi-center single-arm trial, to investigate the safety and efficacy of omburtamab in pediatric patients with neuroblastoma with relapse in the CNS including parenchymal or LM metastases.

The primary endpoint of the trial is 3-year OS rate, with a key secondary endpoint of overall tumor response rate (ORR).

Y-mAbs sought to utilize “interim efficacy, safety and pharmacokinetic data from Study 101 [to] support the BLA resubmission.” 2021 Form 10-K at 81.

As of October 2022, Study 101 was fully enrolled, but survival data remained immature.

21 CFR 314.126 contains the elements required to be satisfied in order to receive FDA approval for omburtamab. A drug or biologic product must demonstrate substantial evidence of effectiveness through adequate and well-controlled studies. To establish effectiveness, it is essential to distinguish the effect of the drug “from influences, such as spontaneous change in course of disease, placebo effect, or biased observation” (21 CFR 314.126(a)).

The FDA declined marketing approval of omburtamab in a Refusal to File (RTF) letter dated October 2, 2020, informing Y-mAbs that additional data, including evidence of durable response were necessary to provide the level of evidence needed to support an approval.

Y-mAbs disclosed the existence of the RTF letter in a press release dated October 5, 2020 and in an investor conference call the morning of October 6, 2020, but misrepresented the FDA’s willingness to approve omburtamab for marketing based on the existing clinical trials.

In fact, throughout the Class Period, beginning on October 6, 2020, Y-mAbs misrepresented to investors that, pursuant to a series of meetings and other communications between Y-mAbs and the FDA, that progress was being made that would align with the FDA’s requirement to demonstrate substantial evidence of effectiveness, sufficient for approval of omburtamab, through adequate and well-controlled studies.

Specifically, the FDA had repeatedly advised the Defendants that the FDA was unlikely to grant approval for the marketing of omburtamab based on a comparison between Study 03-133 and CGCCR because of substantial differences in the patient populations, and the absence of tumor response data, and that Study 101 was neither sufficiently advanced nor indicative of efficacy to justify approval.

The statements alleged to be false and misleading were not forward-looking statements because they misrepresented existing facts based on communications with the FDA with respect to the approval.

The true facts were first disclosed to investors shortly after the opening of trading on October 26, 2022 when the FDA published its Briefing Document for an October 28, 2022 Advisory Committee (“AdCom”) Meeting, and again, on October 28, 2022 when the AdCom vote 16-0 against recommending approval of omburtamab.

The disclosure of the true facts caused Y-mAbs common shares to plummet $11.56 a share from the closing price on October 25, 2022 of $15.17 a share to close on October 31, 2022 at $3.61 a share.

If you purchased or otherwise acquired Y-mAbs shares and suffered a loss, are a long-term stockholder, have information, would like to learn more about these claims, or have any questions concerning this announcement or your rights or interests with respect to these matters, please contact Brandon Walker or Melissa Fortunato by email at investigations@bespc.com, telephone at (212) 355-4648, or by filling out this contact form. There is no cost or obligation to you.

About Bragar Eagel & Squire, P.C.:

Bragar Eagel & Squire, P.C. is a nationally recognized law firm with offices in New York, California, and South Carolina. The firm represents individual and institutional investors in commercial, securities, derivative, and other complex litigation in state and federal courts across the country. For more information about the firm, please visit www.bespc.com. Attorney advertising. Prior results do not guarantee similar outcomes.

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