On March 25, Merck & Co. (MSD) announced a significant strategic move, acquiring Terns Pharmaceuticals for an estimated $6.7 billion through a subsidiary. This acquisition is widely interpreted as a calculated and forward-looking maneuver by MSD to bolster its oncology pipeline, specifically targeting the next generation of haematological assets. The deal comes at a critical juncture for MSD, as the company prepares for the eventual patent exclusivity expiration of its blockbuster immunotherapy, Keytruda. By integrating Terns Pharmaceuticals, MSD aims to diversify its oncology portfolio and deepen its expertise and market presence in the complex field of haematological malignancies.
Strategic Rationale: Addressing Keytruda’s Patent Cliff and Diversifying Oncology
The acquisition of Terns Pharmaceuticals is directly linked to MSD’s long-term strategic planning, particularly concerning the looming patent expiration of Keytruda. Keytruda has been a cornerstone of MSD’s revenue, but the pharmaceutical industry operates under a cyclical model where the loss of exclusivity for a major drug necessitates proactive pipeline development. MSD’s investment in Terns indicates a clear intent to preemptively fill the potential revenue gap and solidify its position in the competitive oncology landscape. The focus on haematological malignancies suggests a strategic choice to invest in areas with significant unmet needs and a strong potential for therapeutic advancement.
TERN-701: A Promising Lead Candidate in Chronic Myelocytic Leukaemia
The centerpiece of the Terns Pharmaceuticals acquisition is TERN-701, an oral allosteric BCR-ABL tyrosine kinase inhibitor (TKI). This novel compound has recently advanced into Phase I/II clinical trials, specifically the CARDINAL study, designed to evaluate its efficacy and safety in patients diagnosed with BCR-ABL1-positive chronic myelocytic leukaemia (CML) who have undergone at least one prior TKI treatment.
The development of TERN-701 has been marked by encouraging early-stage data. Interim results presented at the American Society of Hematology (ASH) 2025 meeting demonstrated substantial therapeutic promise, leading to the drug securing FDA Fast Track Designation in December 2025. This designation signifies that the FDA has recognized TERN-701’s potential to address serious conditions and accelerate the review process, reflecting a shared confidence in its therapeutic value. MSD’s ambitious plans for TERN-701 include the initiation of Phase III trials in both first-line and second-line settings, underscoring a commitment to exploring its full therapeutic spectrum. According to analysis by GlobalData, TERN-701 currently holds a likelihood of approval (LoA) of 20%, a figure that, while indicative of early-stage development, points to significant potential for success.
Clinical Data and Competitive Landscape: TERN-701 vs. Scemblix
The introduction of TERN-701 into the CML treatment landscape sets the stage for a direct competition with Novartis’s established drug, Scemblix (asciminib). Scemblix is already approved and widely used across all lines of therapy for CML, having built a strong reputation based on its efficacy and safety profile. However, emerging data for TERN-701 suggests it could significantly disrupt this established market.
The Phase III ASCEMBL trial, which evaluated Scemblix in 157 patients, reported major molecular response (MMR) rates of 25.5% and deep molecular response (DMR) rates of 10.8% at 24 weeks. In contrast, interim data from the CARDINAL trial, based on a smaller cohort of 32 patients treated with TERN-701, has shown significantly higher MMR rates of 75% and DMR rates of 36%. These figures suggest that TERN-701 has the potential to redefine the benchmarks for response in CML treatment.
It is important to note nuances in these trial comparisons. Both trials involved patients with a history of prior TKI treatment. However, the proportion of patients with elevated baseline BCR-ABL1 levels (>10%) was lower in the TERN-701 cohort (47%) compared to the Scemblix cohort (62%). While this difference might partially contribute to TERN-701’s observed efficacy advantage, it does not fully account for the magnitude of the difference, further highlighting TERN-701’s potential disruptive power.
Long-Term Efficacy and Patient Experience: Addressing Key Differentiators
Further evidence of TERN-701’s disruptive potential emerges from longer-term response data and patient switching findings. At 96 weeks, Scemblix’s MMR rate in the ASCEMBL trial had reached 37.6%. Notably, a significant observation from the Terns data was that six out of ten patients who had previously been treated with Scemblix achieved MMR within 24 weeks of switching to TERN-701. This finding strongly supports Terns’ stated intention to capture a substantial portion of the market currently held by Novartis.
Beyond efficacy, TERN-701 appears to offer a more favourable safety and convenience profile. The incidence of Grade 3 or higher adverse events (AEs) with TERN-701 was reported at 32%, compared to 50% for Scemblix. Furthermore, the rate of AEs leading to treatment discontinuation was considerably lower for TERN-701 (2%) versus Scemblix (5.8%). A significant practical advantage for TERN-701 is its administration, which is unaffected by food intake. This contrasts with Scemblix, which requires a fasting period of three hours before dosing, presenting a considerable inconvenience for patients and potentially impacting adherence. This improved patient experience could be a key factor in its market adoption.
Navigating Regulatory Hurdles and Future Outlook
Despite the compelling early-stage data, TERN-701 faces several critical hurdles before it can successfully challenge established competitors. A key area for further investigation is the current lack of comprehensive data on complete cytogenetic response. Additionally, the durability and robustness of TERN-701’s safety profile need to be rigorously confirmed in larger, later-phase clinical trials. Regulatory agencies are expected to scrutinize these aspects closely as the therapy progresses through pivotal studies and toward potential market approval.
MSD’s strategic acquisition of Terns Pharmaceuticals is thus a testament to its forward-thinking approach in fortifying its oncology franchise. If TERN-701 can consistently demonstrate its early clinical promise in these upcoming trials, it has a realistic prospect of surpassing Scemblix in the CML market. GlobalData forecasts Scemblix to achieve approximately $1.1 billion in sales across the eight major markets (US, France, Germany, Italy, Spain, UK, Japan, and Canada) by 2030, representing roughly one-third of the CML market. Successful development and commercialization of TERN-701 could allow MSD to not only reinforce its leadership in targeted cancer therapies but also to gain a significant competitive edge in a rapidly evolving market, particularly in the post-Keytruda era.
Broader Implications for MSD’s Oncology Strategy
The acquisition of Terns Pharmaceuticals is more than just the addition of a promising drug candidate; it represents a broader strategic shift for MSD. By investing in TERN-701, MSD is demonstrating its commitment to developing targeted therapies that address specific genetic mutations and pathways implicated in cancer. This approach aligns with the growing trend in precision medicine, where treatments are tailored to the individual characteristics of a patient’s tumor.
Furthermore, the $6.7 billion price tag underscores the perceived value and potential of Terns’ pipeline. It signals MSD’s willingness to make substantial investments to secure assets that can drive future growth. This move also signals to the broader biopharmaceutical industry MSD’s intent to remain a dominant force in oncology, even as it navigates the complexities of patent expirations and the increasing pace of scientific innovation. The successful integration of Terns and the eventual launch of TERN-701 will be closely watched as a key indicator of MSD’s ability to adapt and thrive in the dynamic oncology market.
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