On May 18, 2026 Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) reported a strategic research collaboration with Parabilis Medicines to discover and develop multiple therapeutic candidates based on Parabilis’ Helicon peptide platform, with a particular focus on Antibody-Helicon Conjugates (AHCs), a novel class of therapeutics designed to target challenging and historically "undruggable" targets.

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Helicons are stabilized, cell-penetrant alpha-helical peptides designed to engage intracellular protein targets, including flat surfaces not well suited to traditional small molecule binding. The collaboration is designed to explore the use of Helicons both as stand-alone therapies and as part of AHCs.

"This collaboration reflects Regeneron’s approach of advancing cutting-edge and diversified science to produce a robust portfolio of innovative medicines for patients in need," said George D. Yancopoulos, M.D., Ph.D., Board co-Chair, President and Chief Scientific Officer of Regeneron. "In addition to the potential of Helicons to address previously undruggable targets, the collaboration’s intent to couple Helicons to our VelocImmune derived-antibodies so as to precisely deliver them to cells of interest represents an exciting new approach with the potential to create an entirely new therapeutic class that can span multiple therapeutic areas."

Antibody–drug conjugates traditionally use antibodies to selectively deliver drug payloads into target cells to drive cell death from within. The AHCs envisioned by this collaboration are underpinned by the same delivery principle: pairing antibody-targeted cell access with Helicon payloads designed to selectively modulate specific intracellular proteins, including some long considered undruggable.

Under the terms of the agreement, Parabilis is to receive $125 million from Regeneron in the form of a $50 million upfront payment and a commitment to invest $75 million in Parabilis’ next equity financing, subject to certain conditions. Parabilis is also eligible to receive milestone payments for development, regulatory and commercial milestones, as well as tiered royalties up to the low double-digits on future net sales of any approved medicines resulting from the collaboration. With five initial targets, the agreement provides the potential for up to approximately $2.2 billion in total milestone payments to Parabilis. Under the terms of the agreement, additional targets may be pursued upon additional option payments from Regeneron.

The agreement provides for the parties to collaborate to discover new Helicons and AHCs, which Regeneron will then be responsible for advancing through development, manufacturing and worldwide commercialization.

(Press release, Regeneron, MAY 18, 2026, View Source [SID1234665829])

On May 18, 2026 Protara Therapeutics, Inc. (Nasdaq: TARA), a clinical-stage biotechnology company committed to advancing transformative therapies for the treatment of cancer and rare diseases, reported that it will host a virtual webinar for the investment community at 4:30 pm ET on Tuesday, May 19, 2026. The agenda will include an overview of Lymphatic Malformations (LMs), key opinion leader (KOL) perspectives on the burden of disease and current treatment landscape, the market opportunity and regulatory path for TARA-002 and a review of clinical data supporting the use of TARA-002 in LMs.

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The live event and accompanying slides can be accessed visiting the Events and Presentations section of the Company’s website View Source A replay of the webcast will be archived for a limited time following the event.

About TARA-002

TARA-002 is an investigational cell therapy in development for the treatment of NMIBC and of LMs, for which it has been granted Rare Pediatric Disease, Orphan Drug, Breakthrough Therapy and Fast Track designations by the FDA. TARA-002 is a first-in-class TLR2/NOD2 agonist and novel immunopotentiator derived from inactivated Streptococcus pyogenes with a mechanism of action that includes the activation of innate and adaptive immune pathways. When TARA-002 is administered, it is hypothesized that innate and adaptive immune cells within the cyst or tumor are activated and produce a pro-inflammatory response with the release of cytokines such as tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, IL-6, IL-10 and IL-12. TARA-002 also directly kills tumor cells and triggers a host immune response by inducing immunogenic cell death, which further enhances the antitumor immune response.

TARA-002 was developed from the same master cell bank of genetically distinct group A Streptococcus pyogenes as OK-432, a broad immunopotentiator marketed as Picibanil in Japan by Chugai Pharmaceutical Co., Ltd.

About Lymphatic Malformations

Lymphatic Malformations (LMs) are rare, congenital malformations of lymphatic vessels resulting in the failure of these structures to connect or drain into the venous system. Protara’s focus is on macrocystic and mixed cystic LMs, for which there are no currently approved therapies. They are most frequently present in the head and neck region and are diagnosed in early childhood during the period of active lymphatic growth, with more than 50% detected at birth and 90% diagnosed before the age of three years. The most common morbidities and serious manifestations of the disease include compression of the upper aerodigestive tract, including airway obstruction requiring intubation and possible tracheostomy dependence; intralesional bleeding; impingement on critical structures, including nerves, vessels and lymphatics; recurrent infection; and cosmetic and other functional disabilities. TARA-002 has been granted Rare Pediatric Disease, Orphan Drug, Breakthrough Therapy and Fast Track designations by the FDA for the treatment of LMs.

(Press release, Protara Therapeutics, MAY 18, 2026, View Source [SID1234665828])

On May 18, 2026 Microbiotica, a clinical-stage biopharma company developing a pipeline of oral precision microbiome medicines called live biotherapeutic products (LBPs), reported that all primary and secondary objectives were met in its advanced melanoma (MELODY-1) Phase 1b trial.

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MELODY-1 was an international Phase 1b study to evaluate the safety and tolerability of MB097 given in combination with KEYTRUDA (pembrolizumab), MSD’s anti-PD-1 therapy, in patients with advanced melanoma who demonstrated primary resistance to anti-PD-1 therapy. The trial recruited 41 patients at clinical centres in the UK, France, Italy, and Spain.

MB097 could be administered safely in combination with KEYTRUDA with no serious adverse events (SAEs) related to MB097
The nine bacterial strains contained in MB097 demonstrated robust engraftment after dosing, with enhanced engraftment following vancomycin preconditioning
Encouraging signals of efficacy were seen in this difficult to treat, primary-refractory advanced melanoma patient population, suggesting that microbiome modulation with MB097 may overcome resistance to anti-PD-1 therapy.
Detailed results of the study will be presented at a scientific conference during 2026.

Commenting on the study results, Dr Pippa Corrie from Cambridge University Hospitals NHS Foundation Trust, the National Co-ordinating Investigator for the MELODY-1 study said, "There is increasing evidence that the microbiome plays a crucial role in patients’ response to immune checkpoint inhibitors. Clinical benefit has been reported with Faecal Microbiota Transplantations (FMT), while MB097 capsules taken orally each day affords an easy and reproducible way of modifying the microbiome. The MELODY-1 study results show that MB097 is well tolerated, with encouraging early signs of efficacy in a very difficult to treat metastatic melanoma patient population with primary resistance to anti-PD-1 based immunotherapy, in whom there is a significant unmet need."

In this first-in-human, randomised open-label clinical trial, all patients received MB097 and pembrolizumab for up to six months. Half of the participants also received vancomycin before starting the co-therapy to determine whether it helps the bacterial strains in MB097 engraft in the gut more efficiently. Participants benefiting from the treatment at the end of the initial six-month period have entered an extension study and can continue to receive pembrolizumab for up to an additional 18 months. The results of this extension phase will be reported in due course.

MB097 is a once daily, orally administered LBP consisting of a defined consortium of nine strains of commensal bacteria designed to enhance the efficacy of immune checkpoint inhibitors (ICIs). The MELODY-1 study is designed to investigate the safety, tolerability, and initial signals of efficacy of MB097 in advanced (metastatic) melanoma, in combination with KEYTRUDA (pembrolizumab), MSD’s (Merck & Co., Inc., Rahway, NJ, USA) anti-PD-1 therapy, in patients with cutaneous melanoma who have failed to respond to immunotherapies (study identifiers NCT06540391; MSD KEYNOTE-E75; 023-507377-17). MSD has supplied KEYTRUDA to Microbiotica.

Dr Robert Tansley, Microbiotica’s Chief Medical Officer, said, "We are encouraged by these positive data on safety and engraftment. With early signs of efficacy, we look forward to further analysis from the trial respondents. The results provide the foundation to proceed to larger controlled studies in a broader melanoma patient population and we are excited by the potential to deliver a new option to maximise patients’ potential to respond to anti-PD-1 therapy."

Tim Sharpington, Microbiotica’s CEO added, "This is our second clinical trial to report positive results, following the success of our Phase 1b study of MB310 in ulcerative colitis earlier this year. This is further validation of our clinic-first discovery platform and precision microbiome medicine development."

(Press release, Microbiotica, MAY 18, 2026, View Source [SID1234665827])

On May 18, 2026 Merck (NYSE: MRK), known as MSD outside of the United States and Canada, reported the pivotal Phase 3 TroFuse-005 trial evaluating sacituzumab tirumotecan (sac-TMT), an investigational TROP2-directed antibody-drug conjugate (ADC) being developed in collaboration with Kelun-Biotech, met its primary endpoints of overall survival (OS) and progression-free survival (PFS) in certain patients with advanced or recurrent endometrial cancer. TroFuse-005 is the first global Phase 3 trial to demonstrate statistically significant improvement in both OS and PFS compared to chemotherapy for these patients and the first and only ADC to do so for patients with endometrial cancer in this setting.

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At a pre-specified interim analysis, sac-TMT demonstrated a statistically significant and clinically meaningful improvement in OS and PFS compared to treatment of physician’s choice (TPC, consisting of doxorubicin or paclitaxel) for patients with endometrial cancer who have previously received platinum-based chemotherapy and anti-PD-1/L1 immunotherapy either together or separately. The study also reached its key secondary endpoint of objective response rate. These data will be presented at an upcoming medical meeting and discussed with regulatory authorities worldwide.

The safety profile was consistent with what has been observed in previously reported studies of sac-TMT; no new safety signals were observed.

"These results show sac-TMT may be able to address a critical unmet need for certain patients with advanced endometrial cancer, one of the only cancers increasing in both incidence and mortality worldwide," said Dr. Domenica Lorusso, the study’s global lead investigator, lead investigator for ENGOT and professor of Obstetrics and Gynecology at Humanitas University and Humanitas San Pio X, Milan. "Despite recent advances, patients whose disease progresses following treatment with platinum and immunotherapy are urgently in need of new options, and these findings show for the first time that a TROP2 ADC may be an effective option in this setting."

"The scale and ambition of our expansive TroFuse program reflects our deep commitment to advancing one of the industry’s leading ADC pipelines to make a difference for more people facing cancer and builds on our legacy of leadership in gynecologic cancer research," said Dr. Dean Y. Li, president, Merck Research Laboratories. "These findings reinforce our belief that sac-TMT, with its proprietary bifunctional linker designed with the intent to maximize payload delivery to tumors while minimizing impact on healthy cells in the body, has the potential to become a cornerstone in the treatment of certain patients with advanced endometrial cancer. We thank the patients and investigators for participating in our studies as well as our collaborators at Kelun-Biotech for helping us advance this important treatment."

TroFuse-005 also marks the first positive Phase 3 results from Merck’s TroFuse clinical development program for sac-TMT. The program currently consists of 17 ongoing global Phase 3 trials across multiple tumor types, the broadest range of disease and treatment settings compared to any TROP2-directed ADC to date, including 10 Phase 3 trials in women’s cancers. The program is evaluating sac-TMT across a diverse range of tumor types, including endometrial, bladder, breast, cervical, gastric, non-small cell lung and ovarian cancers, and it spans early-to-late-stage disease as both monotherapy and in combination with immunotherapies. This includes the ongoing TroFuse-033 trial in first line mismatch repair proficient endometrial cancer.

About TroFuse-005

TroFuse-005 is a randomized, active-controlled, open-label, multicenter, global Phase 3 trial (ClinicalTrials.gov, NCT06132958) evaluating sac-TMT versus TPC in patients with endometrial carcinoma and carcinosarcoma who have received prior platinum-based chemotherapy and anti-PD-1/anti-PD-L1 immunotherapy either together or separately. The trial enrolled 776 patients who were randomized to receive either sac-TMT or TPC, consisting of doxorubicin or paclitaxel. Sac-TMT (4 mg/kg) was administered on Day 1 of each two-week treatment cycle. Doxorubicin (60 mg/m²) was administered on Day 1 of each three-week treatment cycle and paclitaxel (80 mg/m²) was administered on Days 1, 8 and 15 of each four-week treatment cycle.

The study has dual primary endpoints: PFS by blinded independent central review (BICR), defined as the time from randomization to the first documented disease progression or death from any cause, and OS, defined as the time from randomization to death from any cause. A key secondary endpoint is objective response rate, and other secondary endpoints include duration of response, incidence of adverse events, treatment discontinuation due to adverse events and change from baseline in global health status/quality-of-life scores.

About sacituzumab tirumotecan (sac-TMT)

Sac-TMT is an investigational TROP2-directed ADC with a belotecan-derived topoisomerase I inhibitor payload and a bifunctional linker designed with the potential to maximize payload delivery to tumor cells and minimize payload loss while circulating in the body. Sac-TMT is the only TROP2 ADC designed with a focus on both ends of the linker.

TROP2 is overexpressed on tumor cells compared to healthy cells in many common cancers, and through the TroFuse clinical development program, Merck is evaluating sac-TMT in 17 ongoing global Phase 3 trials across multiple tumor types, the broadest range of disease and treatment settings compared to any TROP2-directed ADC to date. The TroFuse development program spans early‑to-late‑stage disease in more than nine disease areas and includes more than 15,000 patients worldwide. Numerous Phase 3 trials are exploring sac-TMT as monotherapy and in combination with immunotherapies, aiming to improve survival and quality of life for patients with advanced and earlier-stage cancers.

About endometrial cancer

Endometrial cancer (also referred to as endometrial carcinoma) begins in the inner lining of the uterus, which is known as the endometrium, and is the most common type of cancer in the uterus. More than 90% of uterine body cancers occur in the endometrium. In the U.S., it is estimated there will be approximately 68,270 patients diagnosed with endometrial cancer and approximately 14,450 patient deaths from the disease in 2026. Globally, endometrial cancer is the sixth most common cancer in women and the 15th most common cancer overall. Following primary treatment, patients face a risk of their cancer returning, often as distant metastasis, which is associated with poorer outcomes.

(Press release, Merck & Co, MAY 18, 2026, View Source [SID1234665826])

On May 18, 2026 Ligand reported that as previously disclosed, on April 27, 2026, Ligand Pharmaceuticals Incorporated, a Delaware corporation ("Ligand"), entered into an Agreement and Plan of Merger (the "Merger Agreement"), by and among Ligand, XOMA Royalty Corporation, a Nevada corporation ("XOMA Royalty"), and Flex Merger Sub, Inc., a Nevada corporation and wholly-owned subsidiary of Ligand ("Merger Sub"), pursuant to which, and upon the terms and subject to the conditions thereof, including, without limitation, effecting the Holding Company Reorganization (as defined below), Merger Sub will merge with and into a newly formed Nevada corporation, XOMA Royalty Holdings Corporation ("HoldCo"), (the "Merger"), with HoldCo surviving the Merger as a wholly owned subsidiary of Ligand. HoldCo is a wholly-owned subsidiary of XOMA Royalty and was formed for the sole purpose of effecting a holding company reorganization (the "Holding Company Reorganization") pursuant to Nevada Revised Statutes, as amended ("NRS"), 92A (or such other applicable provisions of the NRS).

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On May 16, 2026, XOMA Royalty, Ligand and the Merger Sub entered into Amendment No. 1 to the Agreement and Plan of Merger ("Amendment No. 1") which, among other things, adds HoldCo as a party to the Merger Agreement.

The foregoing description of Amendment No. 1 does not purport to be complete and is qualified in its entirety by reference to Amendment No. 1, a copy of which is attached hereto as Exhibit 2.1 and is incorporated herein by reference.

(Filing, Ligand, MAY 18, 2026, View Source [SID1234665825])