Randi Hernandez was science editor at Pharmaceutical Technology from September 2014 to May 2017.

Randi Hernandez

	Scientists at the National Institute of Allergy and Infectious Diseases (NIAID), a branch of the National Institutes of Health (NIH), have concluded that an antigen other than the one that is typically used for the creation of flu vaccines may be a more effective target for the prevention of infection. Although most current seasonal vaccines attempt to induce the creation of antibodies against the flu cell-surface protein hemagglutinin, researchers from NIH found that neuraminidase (NA) may actually be a better flu cell-surface protein to target. NA is an enzyme that allows the flu virus to exit host cells so it can further replicate in the body. Measuring antibodies to NA may be a better indicator of protection against influenza infection, the researchers hypothesized.

, NIH researchers wrote that recent poor performance of seasonal flu vaccines prompted them to investigate other “immunological correlates of protection” besides the hemagglutinin antigen. Sixty-five healthy volunteers were intranasally inoculated with a wild-type 2009 A (H1N1) pandemic influenza A challenge virus at the NIH Clinical Center. Researchers measured hemagglutinin inhibition (HAI) titer and found that although a higher HAI conferred some protection against the flu (i.e., symptoms were not as severe), neuraminidase inhibition (NAI) titer was a better predictor of overall flu reduction.

	The range for titers of HAI defined as "protective" was originally established in 1972 by Hobson et al. via a live influenza virus challenge, according to the 

 piece. In that study, an HAI of 18 to 36 was found to be associated with 50% protection from infection. Since then, say the researchers, newer epidemiological studies of vaccine performance measuring HAI have shown that this range is associated with less protection than originally thought-and a titer of HAI within the protective range "would not necessarily include the prevention of a clinical influenza-like illness, even if it does predict some reduction in the duration of illness and viral shedding, and thus spread of disease." During the past 10 years, vaccines have had an overall mean effectiveness rate of 40%, they wrote.

	Ultimately, the researchers concluded that NAI titer is a stronger correlate of disease severity than is HAI titer alone, and individuals with high titers of NAI experienced less severe/fewer symptoms and a shorter duration of viral shedding. “This challenge study confirms the importance of NAI titer as a correlate and for the first time establishes that it can be an independent predictor of reduction of all aspects of influenza disease,” the study authors wrote. “This suggests that NAI titer may play a more significant role than previously thought and that neuraminidase immunity should be considered when studying susceptibility after vaccination and as a critical target in future influenza vaccine platforms.” The researchers admitted that HAI and NAI titers, measured together, may even be a better predictor of disease than either titer measured alone.

	Evolving viral phenotypes have also contributed to diminishing effectiveness of seasonal flu vaccines. In fact, in late 2015, 

the Committee on Energy and Commerce concluded

 that the 2014–2015 vaccine did not defend against the dominant H3 A strain of influenza because the virus mutated after vaccine production was already well underway. The antigenic drift meant the 2014–2015 vaccine’s mean overall effectiveness rate was just 19% (

)-the lowest effectiveness rate that has been recorded during the past 10 years.

Articles

Traditional methods of measuring the effectiveness of vaccines against the flu are called into question by new findings from the NIH.

NIH Study Identifies Better Parameter to Predict Flu Vaccine Effectiveness

	Seattle Genetics presented new data on antibody-drug conjugates (ADCs) at the 107

 Annual Meeting of the American Association for Cancer Research (AACR), highlighting preclinical information on novel ADCs and presenting further evidence about the efficacy of auristatin-based ADCs when coupled with checkpoint inhibitors.

	The company presented data on a Phase I preclinical molecule under investigation for the treatment of breast cancer (SGN-LIV1A) and preclinical data on a novel ADC for multiple myeloma (SGN-CD352A). SGN-CD352A is an anti-CD352 engineered cysteine monoclonal antibody (EC-mAb) that targets the antigen CD352 typically found on the surface of B cells in multiple myeloma. Two molecules of cytotoxic agent pyrrolobenzodiazepine (PBD) dimer are attached to the EC-mAb. According to 

, SGN-CD352A demonstrated potent cytotoxic activity in human myeloma and lymphoma cell lines, even in cells that had lower expression levels of CD352-and it caused minimal damage to resting B lymphocytes, unlike many multiple myeloma treatments that kill healthy B cells in addition to cancerous B cells. "In summary, CD352 is a newly validated multiple myeloma tumor antigen and the novel PBD dimer ADC SGN-CD352A shows potent antitumor activity against cell line models of [multiple myeloma] at clinically relevant doses," the authors wrote.

	According to Seattle Genetics scientists, SGN-LIV1A has already demonstrated antitumor activity alone for the treatment of breast cancer. SGN-LIV1A is an anti-LIV-1 antibody connected to a microtubule disruption agent, monomethyl auristatin E. Researchers showed that when combined with standard chemotherapeutic agents, there were "additive and synergistic effects."

	Optimal PEGylation of the auristatin linker in an ADC was also explored by scientists from Seattle Genetics. Researchers tested PEG units of varying lengths in an effort to optimize drug-to-antibody ratio and enhance 

 activity. They found an optimal PEG length for their product-and ADCs prepared with this linker have demonstrated an increase in therapeutic index compared with other monomethylauristatin E-based ADCs, they said.

	Other studies presented at AACR by Seattle Genetics showed that existing FDA-approved ADC Adcetris (brentuximab vedotin)-which is directed at CD30-causes cell death through apoptosis by the disruption of the creation of tubulin. The investigators were able to measure the degree of stress induction and mimotic arrest that Adcetris caused to tumor cells, allowing them to better understand the mechanism of action through which the drug works. They concluded, “Via induction of ER stress, tumor cells killed by auristatin-based ADCs may initiate an antitumor immune response," and may provide "a rationale for exploring therapeutic strategies that combine ADCs with other immune stimulatory regimens."

	Source: American Association of Cancer Research, 

Linker technology and drug combinations play an important role in the efficacy of ADCs.

Seattle Genetics Presents New Antibody-Drug Conjugate Data at AACR

 on April 16, 2016, that its cell manufacturing facilities at the National Cancer Institute (NCI) are undergoing a voluntary internal review by the National Institutes of Health (NIH). Jacob Plieth of EP Vantage 

 on April 17 that as a result of the announcement, at least eight chimeric antigen receptor T (CAR-T) cell or T-cell receptor studies have been suspended at NCI. Although not all of the collaborative projects between Kite and NCI will be affected, all of the projects in which NCI has Cooperative Research and Development Agreements (CRADAs) with Kite will be halted-with the exception of their collaborative project on CD19.

	While the process improvements at the facilities involving sterile materials occur, the trials cannot enroll new patients, although Kite noted it will continue to administer treatment to current enrollees. Kite wrote in a prepared statement, “The review of NCI’s manufacturing facilities is not related to KTE-C19 or Kite’s manufacturing capabilities.” The company said despite the pausing of the trials related to the MAGE antigen, it “remains on track to file an [investigational new drug application] with the FDA by the end of the year” for its product candidate targeting MAGE-A3 for the treatment of solid tumors.

	The T-cell receptor candidates targeting MAGE-A3 are unlike many of the CAR-T therapies that have recently been in the news. “The majority of studies on T cell-based cancer immunotherapy focus on CD8 T cells due to their capability to kill tumor cells directly. However, evidence from preclinical and clinical studies indicates that another type of T cell, CD4 T cell, can also induce tumor regression,” wrote senior author of a study on MAGE-A3, Steven A. Rosenberg, MD, PhD, chief of the Surgery Branch at NCI, in 

 during the American Association for Cancer Research (AACR) meeting. Rosenberg said that this is the first clinical trial testing an immunotherapy that uses gene-engineered CD4 helper T cells against metastatic cancer.

The National Institute of Health will conduct an internal review of the National Cancer Institute’s cell manufacturing facilities, which will affect multiple Kite projects.

Kite Pharma Pauses Selected Clinical Trials

	In a landmark discovery, scientists from Cornell have determined that a drug called Lexiscan (regadenoson injection) is capable of activating adenosine receptors expressed on blood-brain barrier (BBB) cells. Senior author of the study, Margaret Bynoe, associate professor in the department of microbiology and immunology in Cornell’s College of Veterinary Medicine, and Do-Geun Kim, postdoctoral associate, 

 in mouse models that it is possible to deliver chemotherapy drugs and other larger molecules into the brain following a course of the drug Lexiscan. The team also demonstrated that Lexiscan worked in a similar manner on the channels of human primary endothelial cells.

	Typically, molecules of more than 450 daltons are prevented from crossing the BBB to protect the “complex brain physiology and strict ionic environment” of the brain, the researchers wrote in 

. "We can open the BBB for a brief window of time, long enough to deliver therapies to the brain, but not too long so as to harm the brain. We hope in the future, this will be used to treat many types of neurological disorders," said Bynoe in a 

. The researchers said that the discovery could have specific implications for the treatment of Alzheimer’s disease and chemotherapy-resistant cancers that cause brain tumors such as gliomas.

	Lexiscan is A2A adenosine receptor (AR) agonist that temporarily decreases expression of transporter P-glycoprotein (P-gp). P-gp is normally highly expressed on brain endothelial cells and is responsible for blocking the entry of most drugs delivered to the brain. The P-gpo protein is also expressed by many different types of cancers, making them resistant to chemotherapy. The researchers concluded, "A2A AR activation on BBB endothelial cells offers a therapeutic window that can be fine-tuned for drug delivery to the brain and has potential as a [central nervous system] drug-delivery technology."

	Lexiscan was approved by FDA in 2008 as a heart-imaging agent and is manufactured by Astellas. It works by increasing blood flow through the arteries of the heart during a cardiac nuclear stress test and is used specifically for patients who are unable to exercise adequately for the stress test. It is administered prior to a radiopharmaceutical and facilitates the myocardial uptake of the imaging radionuclide.

	Source: Cornell University, ScienceDaily, 

Cornell researchers reveal that an existing FDA-approved drug can facilitate the delivery of other large molecules across the blood-brain barrier.

Researchers Discover a Method to Penetrate the Blood-Brain Barrier

 the first monoclonal antibody (mAb)-based biosimilar on April 5, 2016. Celltrion and Pfizer's Inflectra (infliximab) was given the green light for all indications, except for Remicade’s indication for pediatric ulcerative colitis, which is still covered by orphan drug exclusivity until September 23, 2018. Inflectra is approved to treat a range of inflammatory conditions, including rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, Crohn’s disease, ulcerative colitis, and plaque psoriasis.

recent draft guidance on biosimilar labeling

, the common name of the product is infliximab-dyyb and contains a suffix that does not identify the manufacturer directly or have any specific meaning. This is unlike the naming of the first-ever biosimilar, Sandoz' Zarxio, the biosimilar to Neupogen (filgrastim), which was named before the FDA draft guidance on biosimilar labeling was officially released and has a suffix that identifies the manufacturer (filgrastim-sndz). As it stands, the clinical trial information listed on the 

 is almost exactly the same as the information on the Remicade label, even though the two products are not interchangeable-meaning the Inflectra label contains immunogenicity data pulled from the Remicade label.

	Infliximab, commercialized by Hospira (now owned by Pfizer) under the trade name Inflectra, was approved in 2013 in parts of Europe and in 2015 in West Europe. Celltrion gained approval for infliximab under the name Remsima in 2012 in Korea.

	Although Inflectra has been proven to be highly similar to Janssen Biotech's reference product, Jay Siegel, MD, chief biotechnology officer and head, scientific strategy and policy at Johnson & Johnson, adamantly stressed that infliximab-dyyb is not identical to Remicade. He wrote in a prepared emailed release, “It is important to note that the FDA has not approved Celltrion’s infliximab-dyyb as being interchangeable with Remicade. For FDA to determine a biosimilar is interchangeable with its reference product, a manufacturer must demonstrate that the biosimilar is expected to produce the same clinical result as the reference product in any given patient. In addition, the manufacturer must demonstrate the risk of alternating or switching between the reference product and biosimilar is no greater than the risk of using the reference product.”

	Siegel also warned that J&J's subsidiary Janssen plans to protect its patents for Remicade, which he says remain enforceable until September 2018. He added, "A commercial launch of Celltrion’s infliximab-dyyb in advance of this date would be an infringement of our patents, and we intend to defend our intellectual property rights."

Inflectra is the second biosimilar to hit the market in the United States.

FDA Approves First mAb Biosimilar

	Jack Lew, Obama’s secretary of the treasury, 

 on April 4, 2016, that the US Department of the Treasury and the Internal Revenue Service (IRS) is issuing temporary and proposed regulations to limit the “benefits of and limit the number of corporate tax inversions.” The government bodies also plan to address earnings stripping in these inversions, so it will examine past inversion deals that have already been completed. Some of these may include deals that occurred “within three years prior to the signing date of the latest acquisition,” according to a 

	Lew said that although the Treasury has already tried to take action (in September 2014 and November 2015) to make tax inversions more difficult and less beneficial for companies, many have still found loopholes and have managed to proceed with these types of deals. In a press release, Lew wrote, “I urge Congress to move forward with anti-inversion legislation this year. Ultimately, the best way to address inversions is to reform our business tax system, which is why Treasury is releasing an updated framework on business tax reform…While that work goes on, Congress should not wait to act as inversions continue to erode our tax base.” He said that as a result of these deals, the tax burden is unfairly transferred to American businesses and families, while companies that inverted reap the benefits of having locations in the United States.

	The Treasury will focus on companies that have engaged in a number of acquisitions in series, and it plans to limit a foreign company’s benefits in an inversion. According to the aforementioned Treasury fact sheet, inversion-related tax savings “incentivize foreign-parented firms to load up their US subsidiaries with related-party debt.” In addition, if a transaction does not finance new investment in the US, it will be examined. The measures will make it easier for the IRS to audit for the purposes of conducting a debt-equity tax analysis.

	Many past deals in pharma may be scrutinized as a result of this regulatory measure, as many mergers have allowed pharma to benefit from moving its tax domicile to areas where the corporate tax is much lower than in the US. In the short term, the proposed regulations could all but halt the recently proposed Pfizer/Allergan merger. Says 

, “the Treasury is proposing that, for the purposes of the Pfizer-Allergan deal, none of the shares that resulted from mergers that have occurred in the past three years count.” In other words, the measures could omit the 2015 merger of Actavis and Allergan, Actavis’ 2014 purchase of Forest Laboratories, and a prior Warner Chilcott deal in the calculation of Allergan’s size. An 

 concluded that stripping these deals from calculations could mean that Allergan could then be considered too small a company to serve as Pfizer’s inversion partner, or could limit the economic rewards of the merger. According to the 

, the termination fee is $400 million if the deal is canceled by either party as a result of changes to federal tax laws that restrict or eliminate the benefits of corporate tax inversion.

The meaning of “temporary” and “proposed” regulations


	Because the regulations are not yet law, Terry Haines, the policy analyst at Evercore ISI, wrote in a note to investors that if pharma decides to challenge the new rules, a lengthy litigation may ensue. “What Treasury is trying to do is avoid court scrutiny while discouraging inversions at the same time: if a rule is only ‘proposed’ by a regulator, courts reject lawsuits because the government has not taken a final action that definitely harms someone. This situation, where Treasury is trying to ‘propose’ but yet get specific results against specific transactions, is one where affected companies could try to get federal courts to stay applicability of the proposed regulations.”

	*UPDATE: On April 6, 2016, Pfizer and Allergan formally called off their $160-billion merger due to the new inversion rules. Please see the article 

Pfizer and Allergan Terminate Merger Agreement

Jack Lew, Obama’s secretary of the treasury, announced on April 4, 2016, that the US Department of the Treasury and the Internal Revenue Service (IRS) is issuing temporary and proposed regulations to limit the “benefits of and limit the number of corporate tax inversions.” The government bodies also plan to address earnings stripping in these inversions, so it will examine past inversion deals that have already been completed.