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The research was presented online as part of the 2020 AAN Science Highlights.
SMA results from a mutation in SMN1, which encodes the SMN protein necessary for motor function. Deficiency of this protein causes motor neurons to die, resulting in severe muscle weakness. At 2 years of age, untreated patients with SMA type 1 generally die or require permanent ventilation.
The Food and Drug Administration approved onasemnogene abeparvovec-xioi under the brand name Zolgensma in May 2019. The gene-replacement therapy, which is administered once intravenously, delivers a fully functional copy of human SMN1 into the target motor neuron cells. It is indicated as treatment for SMA in infants younger than 2 years of age.
Preliminary STR1VE data
Preliminary data from the phase 3 STR1VE study were scheduled to be presented at the meeting. The open-label, single-arm, single-dose study enrolled symptomatic patients with SMA type 1 (SMA1) at multiple US sites. Enrollment was completed in May 2019.
The study included 10 male patients and 12 female patients. Participants’ mean age at dosing was 3.7 months. Of 19 patients who could have reached age 13.6 months at data cutoff, 17 (89.5%) were surviving without permanent ventilation, compared with a 25% survival rate among untreated patients. One of the 19 patients died, and the event was judged to be unrelated to treatment. Another of the 19 reached a respiratory endpoint or withdrew consent.
The population’s mean baseline Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP INTEND) score was 32. This score increased by 6.9, 11.7, and 14.3 points at months 1, 3, and 5, respectively. Half of the 22 infants sat independently for 30 or more seconds, and this milestone was achieved at a mean of 8.2 months after treatment. Five of six (83%) patients age 18 months or older sat independently for 30 or more seconds, which was one of the study’s primary endpoints. As of March 8, 2019, treatment-emergent adverse events of special interest were transient and not associated with any sequelae.
The STR1VE study was sponsored by AveXis, the maker of onasemnogene abeparvovec-xioi. Several of the investigators are employees of AveXis, and others received funding from the company.
Long-term follow-up in START
Long-term follow-up data for participants in the phase 1/2a START study also were scheduled to be presented. Patients who completed START were eligible to participate, and the trial’s primary aim was to evaluate the long-term safety of onasemnogene abeparvovec-xioi. Patients are intended to have five annual visits, followed by 10 annual phone calls, and the investigators request local physicians or neurologists to transfer patient records. Safety assessments include medical history and record review, physical examination, clinical laboratory evaluation, and pulmonary assessments. Efficacy assessments include evaluation of the maintenance of developmental milestones.
As of May 31, 2019, 13 patients in two cohorts had been enrolled and had had a baseline visit. For patients in Cohort 2, the mean age and time since dosing were 4.2 years and 3.9 years, respectively. All patients in Cohort 2 were alive and did not require permanent ventilation. Participants did not lose any developmental milestones that they had achieved at the end of START. Two patients were able to walk, and two could stand with assistance during long-term follow-up. This result suggests the durability of the treatment’s effect. No new treatment-related serious adverse events or adverse events of special interest had occurred as of March 8, 2019.
“We know from accumulating experience that treating infants by gene therapy is safe,” said Jerry R. Mendell, MD, the principal investigator and an attending neurologist at Nationwide Children’s Hospital in Columbus, Ohio. “Of the 15 patients we had in our first trial, only four adverse events related to the gene delivery were encountered, and only two of these were considered serious adverse events [i.e., liver enzymes that were 10 times greater than normal laboratory levels]. These laboratory tests occurred without accompanying clinical symptoms or signs. All were suppressed by corticosteroids and related to the liver inflammation. This pattern of safety has been seen in our very large gene therapy experience. No long-term surprises were encountered.”
The START study was sponsored by AveXis. Several of the investigators are employees of AveXis, and others received funding from the company.
Update on the SPR1NT study
Interim safety and efficacy data from the ongoing SPR1NT study, which includes presymptomatic patients, also were scheduled to be presented. The trial “was built on the basic premise that spinal motor neuron degeneration associated with SMN protein deficiency begins in utero, continues to progress rapidly during the first months of life, and is irreversible,” said Kevin Strauss, MD, medical director of the Clinic for Special Children in Strasburg, Pennsylvania. “SPR1NT leveraged the advantages conferred by carrier testing and newborn screening programs for SMA, which allowed the first 22 children enrolled to have a confirmed molecular diagnosis between 1 and 26 days of postnatal life, before the onset of dysphagia, respiratory compromise, or overt weakness.”
In this multicenter, open-label, phase 3 trial, presymptomatic patients age 6 weeks or younger who are expected to develop SMA receive onasemnogene abeparvovec-xioi once and are evaluated during 18 or 24 months. The primary outcomes are sitting for 30 or more seconds for infants with two copies of SMN2 and standing unassisted for infants with three copies of SMN2.
As of December 31, 2019, 29 infants had been treated in the efficacy group at a mean age of 20.6 days among infants with two copies of SMN2 and 28.7 days among infants with three copies of SMN2. All patients are alive, and no patient in SPR1NT required ventilation support at last visit. Among 14 patients with two copies of SMN2, all achieved CHOP INTEND scores of 50 or greater, which exceeds the maximal score observed in untreated patients. Eight have achieved sitting, seven of whom achieved it within the World Health Organization sitting age range of 3.8-9.2 months. The other six patients have not yet passed the WHO developmental window. Among 15 patients with three copies of SMN2, four stood independently and three walked independently, all within the WHO developmental windows of 6.9-16.9 months and 8.2-17.6 months, respectively. The other patients have not yet passed the WHO developmental window. No patient in either cohort required a feeding tube, and most remained within the normal weight range. Treatment-emergent adverse events of special interest were reported in 16 patients. The study is ongoing, and patients continue to meet primary endpoints.
“Comparing functional and motor indices between these two groups [i.e., patients with two copies of SMN2 and those with three copies] should contribute to our understanding of how motor neuron loss during fetal development may impact long-term neurological outcomes over the arc of life and could even form a basis for considering antenatal gene therapy for severe forms of SMA,” said Dr. Strauss.
SPR1NT was funded by AveXis. Several of the investigators are employees of AveXis, and others received funding from the company.
Combination therapy may be a possibility
A benefit of onasemnogene abeparvovec-xioi is that the adeno-associated virus that delivers it does not integrate itself into the genome, said Darryl C. De Vivo, MD, Sidney Carter professor of neurology and professor of pediatrics at Columbia University in New York. “The bad news is that every time the cell divides, the gene therapy goes to one of the two daughter cells, but not to both. ... That means the effectiveness, in theory, would be reduced by 50% with each cell division, possibly affecting the durability of treatment.” The fact that brain and spinal cord neurons are presumed to be fully populated around the time of birth partly mitigates this concern, he added. “There isn’t too much additional cell division going on in neurons after birth at a time when the gene therapy would be administered.”
Furthermore, the cellular distribution of the gene therapy within the nervous system, which is unclear, might affect the therapy’s effect. “These are largely unanswered questions,” said Dr. De Vivo. “The answers to these questions only will come with continued observation of patients who have been treated.”
Considering that nusinersen, the antisense oligonucleotide also approved for SMA, targets SMN2, and the gene therapy replaces SMN1, “there may be some wisdom in thinking about combination therapy,” said Dr. De Vivo. “There’s no doubt that these therapeutic agents are effective,” and continued follow-up will clarify their comparative efficacy, he concluded.
SOURCES: Day JW, et al. AAN 2020. Abstract S27.001. Mendell JR, et al. AAN 2020. Abstract S27.002. Strauss KA, et al. AAN 2020. Abstract S27.003.
The research was presented online as part of the 2020 AAN Science Highlights.
SMA results from a mutation in SMN1, which encodes the SMN protein necessary for motor function. Deficiency of this protein causes motor neurons to die, resulting in severe muscle weakness. At 2 years of age, untreated patients with SMA type 1 generally die or require permanent ventilation.
The Food and Drug Administration approved onasemnogene abeparvovec-xioi under the brand name Zolgensma in May 2019. The gene-replacement therapy, which is administered once intravenously, delivers a fully functional copy of human SMN1 into the target motor neuron cells. It is indicated as treatment for SMA in infants younger than 2 years of age.
Preliminary STR1VE data
Preliminary data from the phase 3 STR1VE study were scheduled to be presented at the meeting. The open-label, single-arm, single-dose study enrolled symptomatic patients with SMA type 1 (SMA1) at multiple US sites. Enrollment was completed in May 2019.
The study included 10 male patients and 12 female patients. Participants’ mean age at dosing was 3.7 months. Of 19 patients who could have reached age 13.6 months at data cutoff, 17 (89.5%) were surviving without permanent ventilation, compared with a 25% survival rate among untreated patients. One of the 19 patients died, and the event was judged to be unrelated to treatment. Another of the 19 reached a respiratory endpoint or withdrew consent.
The population’s mean baseline Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP INTEND) score was 32. This score increased by 6.9, 11.7, and 14.3 points at months 1, 3, and 5, respectively. Half of the 22 infants sat independently for 30 or more seconds, and this milestone was achieved at a mean of 8.2 months after treatment. Five of six (83%) patients age 18 months or older sat independently for 30 or more seconds, which was one of the study’s primary endpoints. As of March 8, 2019, treatment-emergent adverse events of special interest were transient and not associated with any sequelae.
The STR1VE study was sponsored by AveXis, the maker of onasemnogene abeparvovec-xioi. Several of the investigators are employees of AveXis, and others received funding from the company.
Long-term follow-up in START
Long-term follow-up data for participants in the phase 1/2a START study also were scheduled to be presented. Patients who completed START were eligible to participate, and the trial’s primary aim was to evaluate the long-term safety of onasemnogene abeparvovec-xioi. Patients are intended to have five annual visits, followed by 10 annual phone calls, and the investigators request local physicians or neurologists to transfer patient records. Safety assessments include medical history and record review, physical examination, clinical laboratory evaluation, and pulmonary assessments. Efficacy assessments include evaluation of the maintenance of developmental milestones.
As of May 31, 2019, 13 patients in two cohorts had been enrolled and had had a baseline visit. For patients in Cohort 2, the mean age and time since dosing were 4.2 years and 3.9 years, respectively. All patients in Cohort 2 were alive and did not require permanent ventilation. Participants did not lose any developmental milestones that they had achieved at the end of START. Two patients were able to walk, and two could stand with assistance during long-term follow-up. This result suggests the durability of the treatment’s effect. No new treatment-related serious adverse events or adverse events of special interest had occurred as of March 8, 2019.
“We know from accumulating experience that treating infants by gene therapy is safe,” said Jerry R. Mendell, MD, the principal investigator and an attending neurologist at Nationwide Children’s Hospital in Columbus, Ohio. “Of the 15 patients we had in our first trial, only four adverse events related to the gene delivery were encountered, and only two of these were considered serious adverse events [i.e., liver enzymes that were 10 times greater than normal laboratory levels]. These laboratory tests occurred without accompanying clinical symptoms or signs. All were suppressed by corticosteroids and related to the liver inflammation. This pattern of safety has been seen in our very large gene therapy experience. No long-term surprises were encountered.”
The START study was sponsored by AveXis. Several of the investigators are employees of AveXis, and others received funding from the company.
Update on the SPR1NT study
Interim safety and efficacy data from the ongoing SPR1NT study, which includes presymptomatic patients, also were scheduled to be presented. The trial “was built on the basic premise that spinal motor neuron degeneration associated with SMN protein deficiency begins in utero, continues to progress rapidly during the first months of life, and is irreversible,” said Kevin Strauss, MD, medical director of the Clinic for Special Children in Strasburg, Pennsylvania. “SPR1NT leveraged the advantages conferred by carrier testing and newborn screening programs for SMA, which allowed the first 22 children enrolled to have a confirmed molecular diagnosis between 1 and 26 days of postnatal life, before the onset of dysphagia, respiratory compromise, or overt weakness.”
In this multicenter, open-label, phase 3 trial, presymptomatic patients age 6 weeks or younger who are expected to develop SMA receive onasemnogene abeparvovec-xioi once and are evaluated during 18 or 24 months. The primary outcomes are sitting for 30 or more seconds for infants with two copies of SMN2 and standing unassisted for infants with three copies of SMN2.
As of December 31, 2019, 29 infants had been treated in the efficacy group at a mean age of 20.6 days among infants with two copies of SMN2 and 28.7 days among infants with three copies of SMN2. All patients are alive, and no patient in SPR1NT required ventilation support at last visit. Among 14 patients with two copies of SMN2, all achieved CHOP INTEND scores of 50 or greater, which exceeds the maximal score observed in untreated patients. Eight have achieved sitting, seven of whom achieved it within the World Health Organization sitting age range of 3.8-9.2 months. The other six patients have not yet passed the WHO developmental window. Among 15 patients with three copies of SMN2, four stood independently and three walked independently, all within the WHO developmental windows of 6.9-16.9 months and 8.2-17.6 months, respectively. The other patients have not yet passed the WHO developmental window. No patient in either cohort required a feeding tube, and most remained within the normal weight range. Treatment-emergent adverse events of special interest were reported in 16 patients. The study is ongoing, and patients continue to meet primary endpoints.
“Comparing functional and motor indices between these two groups [i.e., patients with two copies of SMN2 and those with three copies] should contribute to our understanding of how motor neuron loss during fetal development may impact long-term neurological outcomes over the arc of life and could even form a basis for considering antenatal gene therapy for severe forms of SMA,” said Dr. Strauss.
SPR1NT was funded by AveXis. Several of the investigators are employees of AveXis, and others received funding from the company.
Combination therapy may be a possibility
A benefit of onasemnogene abeparvovec-xioi is that the adeno-associated virus that delivers it does not integrate itself into the genome, said Darryl C. De Vivo, MD, Sidney Carter professor of neurology and professor of pediatrics at Columbia University in New York. “The bad news is that every time the cell divides, the gene therapy goes to one of the two daughter cells, but not to both. ... That means the effectiveness, in theory, would be reduced by 50% with each cell division, possibly affecting the durability of treatment.” The fact that brain and spinal cord neurons are presumed to be fully populated around the time of birth partly mitigates this concern, he added. “There isn’t too much additional cell division going on in neurons after birth at a time when the gene therapy would be administered.”
Furthermore, the cellular distribution of the gene therapy within the nervous system, which is unclear, might affect the therapy’s effect. “These are largely unanswered questions,” said Dr. De Vivo. “The answers to these questions only will come with continued observation of patients who have been treated.”
Considering that nusinersen, the antisense oligonucleotide also approved for SMA, targets SMN2, and the gene therapy replaces SMN1, “there may be some wisdom in thinking about combination therapy,” said Dr. De Vivo. “There’s no doubt that these therapeutic agents are effective,” and continued follow-up will clarify their comparative efficacy, he concluded.
SOURCES: Day JW, et al. AAN 2020. Abstract S27.001. Mendell JR, et al. AAN 2020. Abstract S27.002. Strauss KA, et al. AAN 2020. Abstract S27.003.
The research was presented online as part of the 2020 AAN Science Highlights.
SMA results from a mutation in SMN1, which encodes the SMN protein necessary for motor function. Deficiency of this protein causes motor neurons to die, resulting in severe muscle weakness. At 2 years of age, untreated patients with SMA type 1 generally die or require permanent ventilation.
The Food and Drug Administration approved onasemnogene abeparvovec-xioi under the brand name Zolgensma in May 2019. The gene-replacement therapy, which is administered once intravenously, delivers a fully functional copy of human SMN1 into the target motor neuron cells. It is indicated as treatment for SMA in infants younger than 2 years of age.
Preliminary STR1VE data
Preliminary data from the phase 3 STR1VE study were scheduled to be presented at the meeting. The open-label, single-arm, single-dose study enrolled symptomatic patients with SMA type 1 (SMA1) at multiple US sites. Enrollment was completed in May 2019.
The study included 10 male patients and 12 female patients. Participants’ mean age at dosing was 3.7 months. Of 19 patients who could have reached age 13.6 months at data cutoff, 17 (89.5%) were surviving without permanent ventilation, compared with a 25% survival rate among untreated patients. One of the 19 patients died, and the event was judged to be unrelated to treatment. Another of the 19 reached a respiratory endpoint or withdrew consent.
The population’s mean baseline Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP INTEND) score was 32. This score increased by 6.9, 11.7, and 14.3 points at months 1, 3, and 5, respectively. Half of the 22 infants sat independently for 30 or more seconds, and this milestone was achieved at a mean of 8.2 months after treatment. Five of six (83%) patients age 18 months or older sat independently for 30 or more seconds, which was one of the study’s primary endpoints. As of March 8, 2019, treatment-emergent adverse events of special interest were transient and not associated with any sequelae.
The STR1VE study was sponsored by AveXis, the maker of onasemnogene abeparvovec-xioi. Several of the investigators are employees of AveXis, and others received funding from the company.
Long-term follow-up in START
Long-term follow-up data for participants in the phase 1/2a START study also were scheduled to be presented. Patients who completed START were eligible to participate, and the trial’s primary aim was to evaluate the long-term safety of onasemnogene abeparvovec-xioi. Patients are intended to have five annual visits, followed by 10 annual phone calls, and the investigators request local physicians or neurologists to transfer patient records. Safety assessments include medical history and record review, physical examination, clinical laboratory evaluation, and pulmonary assessments. Efficacy assessments include evaluation of the maintenance of developmental milestones.
As of May 31, 2019, 13 patients in two cohorts had been enrolled and had had a baseline visit. For patients in Cohort 2, the mean age and time since dosing were 4.2 years and 3.9 years, respectively. All patients in Cohort 2 were alive and did not require permanent ventilation. Participants did not lose any developmental milestones that they had achieved at the end of START. Two patients were able to walk, and two could stand with assistance during long-term follow-up. This result suggests the durability of the treatment’s effect. No new treatment-related serious adverse events or adverse events of special interest had occurred as of March 8, 2019.
“We know from accumulating experience that treating infants by gene therapy is safe,” said Jerry R. Mendell, MD, the principal investigator and an attending neurologist at Nationwide Children’s Hospital in Columbus, Ohio. “Of the 15 patients we had in our first trial, only four adverse events related to the gene delivery were encountered, and only two of these were considered serious adverse events [i.e., liver enzymes that were 10 times greater than normal laboratory levels]. These laboratory tests occurred without accompanying clinical symptoms or signs. All were suppressed by corticosteroids and related to the liver inflammation. This pattern of safety has been seen in our very large gene therapy experience. No long-term surprises were encountered.”
The START study was sponsored by AveXis. Several of the investigators are employees of AveXis, and others received funding from the company.
Update on the SPR1NT study
Interim safety and efficacy data from the ongoing SPR1NT study, which includes presymptomatic patients, also were scheduled to be presented. The trial “was built on the basic premise that spinal motor neuron degeneration associated with SMN protein deficiency begins in utero, continues to progress rapidly during the first months of life, and is irreversible,” said Kevin Strauss, MD, medical director of the Clinic for Special Children in Strasburg, Pennsylvania. “SPR1NT leveraged the advantages conferred by carrier testing and newborn screening programs for SMA, which allowed the first 22 children enrolled to have a confirmed molecular diagnosis between 1 and 26 days of postnatal life, before the onset of dysphagia, respiratory compromise, or overt weakness.”
In this multicenter, open-label, phase 3 trial, presymptomatic patients age 6 weeks or younger who are expected to develop SMA receive onasemnogene abeparvovec-xioi once and are evaluated during 18 or 24 months. The primary outcomes are sitting for 30 or more seconds for infants with two copies of SMN2 and standing unassisted for infants with three copies of SMN2.
As of December 31, 2019, 29 infants had been treated in the efficacy group at a mean age of 20.6 days among infants with two copies of SMN2 and 28.7 days among infants with three copies of SMN2. All patients are alive, and no patient in SPR1NT required ventilation support at last visit. Among 14 patients with two copies of SMN2, all achieved CHOP INTEND scores of 50 or greater, which exceeds the maximal score observed in untreated patients. Eight have achieved sitting, seven of whom achieved it within the World Health Organization sitting age range of 3.8-9.2 months. The other six patients have not yet passed the WHO developmental window. Among 15 patients with three copies of SMN2, four stood independently and three walked independently, all within the WHO developmental windows of 6.9-16.9 months and 8.2-17.6 months, respectively. The other patients have not yet passed the WHO developmental window. No patient in either cohort required a feeding tube, and most remained within the normal weight range. Treatment-emergent adverse events of special interest were reported in 16 patients. The study is ongoing, and patients continue to meet primary endpoints.
“Comparing functional and motor indices between these two groups [i.e., patients with two copies of SMN2 and those with three copies] should contribute to our understanding of how motor neuron loss during fetal development may impact long-term neurological outcomes over the arc of life and could even form a basis for considering antenatal gene therapy for severe forms of SMA,” said Dr. Strauss.
SPR1NT was funded by AveXis. Several of the investigators are employees of AveXis, and others received funding from the company.
Combination therapy may be a possibility
A benefit of onasemnogene abeparvovec-xioi is that the adeno-associated virus that delivers it does not integrate itself into the genome, said Darryl C. De Vivo, MD, Sidney Carter professor of neurology and professor of pediatrics at Columbia University in New York. “The bad news is that every time the cell divides, the gene therapy goes to one of the two daughter cells, but not to both. ... That means the effectiveness, in theory, would be reduced by 50% with each cell division, possibly affecting the durability of treatment.” The fact that brain and spinal cord neurons are presumed to be fully populated around the time of birth partly mitigates this concern, he added. “There isn’t too much additional cell division going on in neurons after birth at a time when the gene therapy would be administered.”
Furthermore, the cellular distribution of the gene therapy within the nervous system, which is unclear, might affect the therapy’s effect. “These are largely unanswered questions,” said Dr. De Vivo. “The answers to these questions only will come with continued observation of patients who have been treated.”
Considering that nusinersen, the antisense oligonucleotide also approved for SMA, targets SMN2, and the gene therapy replaces SMN1, “there may be some wisdom in thinking about combination therapy,” said Dr. De Vivo. “There’s no doubt that these therapeutic agents are effective,” and continued follow-up will clarify their comparative efficacy, he concluded.
SOURCES: Day JW, et al. AAN 2020. Abstract S27.001. Mendell JR, et al. AAN 2020. Abstract S27.002. Strauss KA, et al. AAN 2020. Abstract S27.003.
FROM AAN 2020
