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APHB: Reports Positive Interim Results for Expanded Access Program

By David Bautz, PhD


Positive Interim Results for Single-Patient Expanded Access Program

On January 3, 2018, AmpliPhi Biosciences Corp. (NYSE:APHB) announced positive interim results from the company’s single-patient expanded access program. A total of seven patients with serious or life-threatening infections, which were not responding to antibiotic therapy, were treated with AB-SA01 (n=4) or AB-PA01 (n=3). Six out of the seven patients (86%) achieved “treatment success”, which was defined as complete resolution or significant improvement of baseline signs and symptoms. 

AmpliPhi is developing bacteriophage therapeutics for the treatment of bacterial infections. Bacteriophages are viruses that infect, replicate in, and kill bacterial cells while not harming eukaryotic cells. This exclusivity is vital to their use in combating infectious diseases, and their unique mechanism of action compared to traditional antibiotics means they can be used in place of or in conjunction with those therapies. AB-SA01 is being developed for the treatment of Staphylococcus aureus infections, including methicillin-resistant S. aureus (MRSA) infections. It contains three phage constituents that target greater than 96.7% of S. aureus isolates from a global diversity panel. AB-PA01 is being developed for the treatment of Pseudomonas aeruginosa infections. It contains four phage constituents that target approximately 80% of P. aeruginosa strains, including multi-drug resistant isolates.

The company’s strategy is to use single patient expanded access protocols (Emergency IND in the U.S. and Special Access Scheme in Australia) to derive real-world data using AB-SA01 and AB-PA01 in patients suffering from severe, multidrug-resistant (MDR) infections. The following schematic shows the treatment schedule for the expanded access protocol. In order for a patient to qualify, they would need to have a serious or life-threatening infection that was not responding to antibiotics and that was also susceptible to either AB-SA01 or AB-PA01. Testing to confirm susceptibility to AB-SA01 or AB-PA01 can be performed in approximately 48 hours. 

The characteristics of the seven patients treated thus far under the expanded access protocol are in the following slide. The APACHE II (Acute Physiology And Chronic Health Evaluation II) score is designed to measure the severity of disease of patients admitted to the intensive care unit (Knaus et al., 1985). The score (0-71) is calculated from the patient’s age and 12 physiological measurements, with a higher score signifying more severe disease and a higher risk of death. 

Importantly, both AB-SA01 and AB-PA01 were safe and well-tolerated with no treatment-related serious adverse events (SAE). A total of 90 intravenous (IV) doses of AB-SA01 and a total of 402 IV and 92 inhaled doses of AB-PA01 were administered. 

The following slide shows the clinical outcomes for the seven patients. Six of the seven were classified as “treatment success”, meaning that they had a complete resolution or significant improvement of baseline signs and symptoms while one patient failed treatment. The patient who failed presented with septic shock and an APACHE II score of 47 at baseline (which equates to a predicted mortality risk of 97%). The patient was not responding to antibiotic treatment, and following three days of bacteriophage therapy they died during surgery on day 3. The treating physician deemed the death as unrelated to bacteriophage treatment.

The following slide shows that while there was one death during the first 28 days following treatment, there were no deaths reported in the Day 28-90 period, with some follow-ups still ongoing. We believe this is indicative of the bacteriophage treatment helping to eliminate the infection, and not just delay a negative outcome. The average APACHE II predicted mortality for the seven patients was 46% (with three patients predicted mortality >85%), thus having a mortality rate of only 14% in this group is very encouraging.


Based on the data shown above, AmpliPhi’s strategic focus appears to be off to a successful start. While the number of patients treated thus far is small, it is very encouraging that six out of seven patients achieved treatment success. Based on these results we have adjusted our model by increasing the probability of approval to 60% for AB-SA01 and AB-PA01 in treating resistant hospital acquired infections. Our current valuation is $5.00 per share. However, we believe there is likely to be significant upside to our model once we learn more about what indications the company will be targeting later in 2018 for Phase 2 studies, at which time we may also get a better sense of timelines for approval.  


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