Inclacumab

iStock/ YuLi4ka In the wake of Pfizer’s voluntary market withdrawal of the popular sickle cell disease therapy, BioSpace looks at five investigational drugs currently making their way through the pipeline. A recent fumble has left the sickle cell disease community reeling . Last month, Pfizer abruptly pulled Oxbryta from all global markets after new data showed a higher risk of deaths and complications in treated patients. “[Oxbryta] was one of four medications which we would describe as disease-modifying,” Clifford Takemoto, director of clinical hematology at St. Jude Children’s Research Hospital, told BioSpace . Since the approval of Bristol Myers Squibb’s hydroxyurea for sickle cell disease (SCD) in 1998, only three disease-modifying medications have entered the market, he said. Oxbryta, which won FDA accelerated approval in November 2019, was one of these. Another, Novartis’ Adakveo, has also been called into question after failing to reduce vaso-occlusive crises (VOC) in people with SCD in a Phase III trial last year. EU regulators formally revoked Adakveo’s approval in August 2023, but it remains available in the U.S. “We were optimistic that things were changing,” Takemoto said. “People had hoped that these medications would make a difference.” SCD affects more than 100,000 people in the U.S. and 8 million worldwide. With so few treatment options, it remains a seriously underserved population . Takemoto said the Oxbryta withdrawal has left some patients a “bit angry” and distrustful of new medications, and the question for the community remains: “What’s next?” For Takemoto, the ultimate hope for SCD treatment lies in next-gen transplantation and gene therapy. With the approval of bluebird bio’s Lyfgenia and Vertex and CRISPR Therapeutics’ Casgevy, the potential for gene therapies in SCD is there, even if the rollout is slow and for most, not very accessible, he said. St. Jude is developing its own gene therapy, which the research hospital hopes to move into clinical trials sometime next year. Takemoto also pointed to work being done in bone marrow transplantation intended to reduce toxicity and improve success rates. St. Jude is working on a process that will utilize a “half match,” where a parent’s bone marrow can be used instead of a sibling. These treatments could be transformative, Takemoto said. Here, BioSpace looks at five investigational therapies making their way through the SCD pipeline. Pfizer’s Inclacumab and Osivelotor Oxbryta is not the only SCD asset Pfizer brought onboard with its 2022 acquisition of Global Blood Therapeutics . Two other investigational therapies, inclacumab and osivelotor, were also part of the deal. Inclacumab, a P-selectin inhibitor, is currently being assessed in a Phase III trial to determine its safety and efficacy in reducing VOC. The drug works by binding to P-selectin, a cell adhesion molecule found on platelets. According to Pfizer, this prevents platelets from aggregating, which in turn, is expected to help maintain normal blood flow. Like Oxbryta, osivelotor is a sickle hemoglobin polymerization inhibitor, but with a next-generation design. The asset is currently being studied in a Phase II/III study slated for completion in 2028. While Pfizer has not stated whether the recent findings related to Oxbryta will impact the development of osivelotor, Leerink Partners noted that a Phase II study raised safety concerns, with treatment-emergent adverse events seen in 8 out of 35 patients. Agios Pharmaceuticals’ Mitapivat Agios Pharmaceuticals is developing mitapivat, a pyruvate kinase (PK) activator that is already approved for the treatment of hemolytic anemia in adults with PK deficiency, for SCD. Red blood cells require the PK enzyme for energy, Takemoto explained. In December 2023, the company presented positive data from the Phase II portion of its pivotal RISE UP study. The annualized rate of sickle cell pain crises for patients in the higher dose treatment arm was 0.51 compared to 1.71 for participants in the placebo arm. Takemoto said the oral medication seems to benefit red blood cell health in general and noted that the data look favorable for patients with SCD and other hemolytic anemias. But not everyone is as convinced. Leerink Partners analysts wrote last month of concerns that similar physiological effects could be seen with both Oxbryta and mitapivat. A Phase III readout is expected next year, and the company is targeting a label expansion in 2026. Novo Nordisk’s Etavopivat In 2022, Novo Nordisk paid $1.1 billion to acquire Forma Therapeutics, gaining a lead SCD asset, etavopivat, in the deal. Like mitapivat, etavopivat is also a PK activator, but Novo’s candidate comes with a potential advantage —once daily dosing, versus mitapivat’s twice daily regimen. Etavopivat is currently being studied in a Phase III trial slated for completion in 2026. Phase I data presented by Forma at the American Society of Hematology’s annual meeting in 2021 showed a “sustained increase in hemoglobin and improvement in biomarkers of hemolysis and red blood cell health.” The results, from 15 patients dosed for up to 12 weeks, also showed a trend toward decreasing VOC compared to the 12 months prior to their entering the trial. Takemoto said the candidate “looks very promising” so far but acknowledged that “there are things we don’t know about it. We may learn new side effects as it’s used.” St. Jude will serve as a site for the Phase III trial. Fulcrum Therapeutics’ Pociredir Fulcrum Therapeutics ’ pociredir, a polycomb repressive complex 2 (PRC2) inhibitor, is designed to induce expression of fetal hemoglobin to compensate for the mutated hemoglobin that occurs in SCD. The development path for pociredir has not been without bumps. In February 2023, the FDA slapped Fulcrum with a clinical hold based on previously submitted preclinical data and non-clinical and clinical evidence of hematological malignancies observed with other PRC2 inhibitors. The hold was released six months later. The small molecule, which is currently being studied in a Phase Ib trial, has been well-tolerated in people with SCD with no treatment-related adverse events reported after up to three months exposure, according to a press release announcing the lifted clinical hold.

Pfizer has announced an important decision to voluntarily withdraw all approved OXBRYTA® (voxelotor) lots for the treatment of sickle cell anemia (SCD) and to suspend clinical trials of voxelotor worldwide and its expanded access program. This move follows a review of recent clinical data showing that the overall benefit-risk ratio of OXBRYTA in the treatment of sickle-cell anemia no longer supports its continued use in the market. Specifically, the drug does not effectively manage complications and reduce the risk of death, and may increase the risk of serious adverse events such as vascular occlusive crises. Looking back, Pfizer paid as much as $5.4 billion to acquire this product, which has been successfully launched, and has high hopes for it. However, the rapid delisting of OXBRYTA has undoubtedly dealt a heavy blow to Pfizer's presence in this area, clouding the prospects for its sickle cell anemia treatment. Pfizer's investment in sickle cell anemia is based on the broad market demand for the disease. Although the incidence is low in developed countries, around 4.5 million people worldwide are affected by the disease, and more than 45 million carry the sickle cell gene. This large patient population provides Pfizer with significant market potential. As a result, Pfizer started laying out several years ago and acquired Global Blood Therapeutics (GBT) in 2022 for $5.4 billion, with OXBRYTA as one of its core products. However, although OXBRYTA inhibits sickle hemoglobin polymerization by enhancing hemoglobin's affinity for oxygen, thereby alleviating hemolytic anemia, its market performance has not met expectations. It is important to note that Pfizer's setback in sickle cell anemia is not an isolated event. The company also recently ended two late-stage clinical trials of another drug candidate, inclacumab, due to patient recruitment difficulties. This series of events shows that Pfizer's exploration of the sickle cell anemia market has not been easy. Still, Pfizer said it does not expect OXBRYTA's delisting decision to have a material impact on its financial outlook for 2024. This statement reflects Pfizer's steadiness and rationality in responding to market changes. From a larger perspective, Pfizer's failure in sickle cell anemia is also an inevitable result of increased competition in the industry. In recent years, with the rapid development of gene therapy and FDA approval of multiple gene therapies for sickle cell anemia, such as Vertex and CRISPR Therapeutics' Casgevy and Bluebird Bio's Lyfgenia, traditional medicines have faced unprecedented challenges. These gene therapies, which directly correct gene defects to achieve the goal of disease treatment or even a one-time cure, bring new hope to patients with blood diseases. Although gene therapy shows great potential in the field of medicine, its high cost remains a major challenge that cannot be ignored. For example, Vertex and CRISPR's Casgevy are priced at $2.2 million, while Bluebird Bio's Lyfgenia is priced at $3.1 million, sparking widespread social concern and deep concerns about its accessibility. In fact, most gene therapies cost more than $1 million, with some treatments costing as much as $3.5 million. Earlier this year, after an in-depth review by the Institute for Clinical and Economic Review (ICER), it was noted that a reasonable balance of cost-effectiveness could be achieved if Vertex and bluebird therapies were priced in the range of $1.35 million to $2.05 million. However, we should also face up to the whole new era created by cell gene therapy in the field of blood disease treatment, and its contribution and value cannot be ignored. Pfizer's recent failure in sickle-cell anemia once again highlights the complexity and uncertainty of the pharmaceutical industry. While Pfizer has long considered sickle-cell anemia products a strategic priority, its experimental drug rivipansel failed to perform as expected in the pivotal Phase III clinical study RESET, ultimately forcing the company to make a strategic change. In order to compensate for this deficiency, Pfizer chose to further improve its product line through mergers and acquisitions. Thanks to strong sales of COVID-19 vaccines, Pfizer now has ample financial firepower to fund its M&A strategy. However, "money for medicine" is not a long-term solution. As the dividend of COVID-19 gradually fades and the focus of the industry continues to shift, Pfizer has to face the reality of lower revenue expectations. Since the beginning of 2023, Pfizer shares have fallen by nearly half, from nearly $57 to $28.93. In response, Pfizer has launched a "cost reduction program" and plans to achieve $4 billion in savings by the end of 2024, $500 million less than previously expected. Company executives said the cost cuts will focus on research and development, but also involve optimizing sales and administrative functions. Entering the "post-COVID-19 era," Pfizer is experiencing unprecedented challenges and volatility. The decision to completely abandon the sickle cell anemia product line is not only a positive response to the current difficult situation, but also an important step in Pfizer's pursuit of greater certainty. However, in the face of the great pressure of competition from large manufacturers and the constantly changing industry environment, Pfizer's transformation road still has a long way to go. Whether it can find new growth points and achieve sustainable development in the future is still a problem worthy of attention.