TOP: Recombinant Human Parathyroid Hormone (ALX1-11) on Fracture Incidence in Women With Postmenopausal Osteoporosis

Parathyroid hormone (PTH), a polypeptide consisting of 84 amino acids that is synthesized and secreted by the parathyroid glands, is a principal regulator of calcium homeostasis through concerted action on kidney, intestine and bone. Parathyroid hormone exerts its action on bone to release calcium into the extracellular fluid as a process of bone remodeling and also to maintain the serum calcium concentration, but the exact mechanisms are not fully understood. In some circumstances, PTH may exert an anabolic action on bone and can stimulate osteoblast proliferation and mature osteoblast function. The net effect of exogenous PTH administration on bone turnover depends on the pattern of delivery. A continuous long-term infusion gives a net decrease in trabecular bone volume, whereas daily single injections result in a net increase.

NPS Allelix Corp. is developing ALX1-11, recombinant human parathyroid hormone (1-84), for the treatment of osteoporosis. ALX1-11 is identical to the endogenous intact 84 amino acid human hormone and will be self-administered on a daily basis by subcutaneous (sc) injection.

Currently, there is no approved therapy for osteoporosis capable of stimulating the formation of new bone of normal composition and structure. Most therapies in development are anti-catabolic and only prevent further bone loss (e.g., estrogen replacement, bisphosphonates, and calcitonins). ALX1-11 has the potential to stimulate new bone formation in osteoporotic patients, thereby increasing bone mass and preventing fractures. Patients with moderately or severely reduced bone density and a fracture would be expected to benefit from treatment, thereby improving functional status and alleviating symptoms.

Inclusion criteria

• Women who are postmenopausal with at least one year since the last menstruation.
• Women who are 45-54 years of age with the following bone mineral density (BMD) and/or vertebral fracture:

• BMD 3.0 standard deviations (SDs) or more below peak bone mass of young females at the lumbar spine, femoral neck, or total hip; or
• BMD 2.5 SDs or more below peak bone mass of young females at the lumbar spine, femoral neck or total hip with the presence of a vertebral fracture verified by the central imaging organization before the patient is enrolled into the study.
• Women 55 or more years of age with the following BMD and/or vertebral fracture:

• BMD 2.5 SDs or more below peak bone mass of young females at the lumbar spine, femoral neck or total hip; or
• BMD 2.0 SDs or more below peak bone mass of young females at the lumbar spine, femoral neck or total hip with the presence of a vertebral fracture verified by the central imaging organization before the patient is enrolled into the study.
• The following types of vertebral fractures should not be considered for patient enrollment into this trial:

• Pathological fractures due to malignant disease or infection
• Fractures due to excessive trauma sufficient to cause a fracture in young individuals with normal bone mass
• Women with the ability to self-administer a daily injection or have a designee who will give the injections
• Women who are capable of understanding and giving written, voluntary informed consent before the clinical trial screening visit

Exclusion criteria

A. Vertebral Deformity:

• Patient has 5 or more vertebral (thoracic and lumbar) deformities
• Patient has 2 or more lumbar vertebral deformities (L1 to L4)
• Severe lumbar scoliosis (>15 degrees) which precludes a reliable evaluation of the dual x-ray absorptiometry (DXA)

B. DXA Imaging:

• Inability to have a DXA scan performed.

C. History or Concurrent Illness:

• Disorders of immunity
• Endocrine system
• Gastrointestinal system
• Kidney and collecting system
• Liver, biliary tract and pancreatic systems
• Musculoskeletal system
• Neoplasia
• Nervous system
• Vascular, respiratory and cardiac system
• Significant diseases or disorders are determined by history, physical exam or laboratory screens and judged by the Principal Investigator to be significant.

D. Concurrent Medication:

Any patient who does not require medication washout (discontinuation) as specified below may start study drug dosing after 2 weeks of stabilization treatment with calcium and vitamin D3 supplements. All exceptions will be documented in the case report form (CRF).

• Patients cannot be enrolled into this clinical trial if they have received any of the following therapies at any time:

• Any PTH or PTH analogs [e.g., rhPTH(1-84), PTH(1-34), PTHrP and analogs]
• Fluoride
• Strontium
• Patients must have been off the following agents for the specified times before entering the screening phase of this clinical trial:

• Any investigational drug (30 days)
• Anabolic steroids or androgens (6 consecutive months)
• Active vitamin D3 metabolites and analogs(90 days)
• Systemic corticosteroids, more than 5 mg/day prednisone or a systemic corticosteroid formulation equivalent to 5 mg/day prednisone (12 consecutive months).
• A patient who has been enrolled in the study and needs to receive an acute bolus of steroids (oral or injectable) for a self-limited illness may continue treatment in the study if the following requirements are met:

• Exposure to steroids is limited to no more than 30 consecutive days
• The maximal dose of steroid (prednisone equivalent) is limited to no more than 225 mg (7.5 mg each day for 30 days)
• The illness is acute in nature and is not expected to recur during the remaining treatment period of the study
• Daily inhaled corticosteroids unless dose is below 1200 mg/day of beclomethasone.
• Bisphosphonates, including investigational bisphosphonates.
• Intravenous (IV) pamidronate. Patient must be receiving pamidronate specifically to treat osteoporosis. Patient can have received only ONE IV dose of pamidronate in the 12 months immediately preceding the screening visit.
• Cyclical etidronate. Exposure to cyclical etidronate must be less than or equal to 6 months on a standard dose (e.g. 400 mg/day). Patient should not have exposure to cyclical etidronate for 9 months prior to the screening visit.
• Phenytoin for seizure control. If the patient has received phenytoin within five years of the screening visit, the patient is excluded from this study. The patient may continue in the screening process if 15 years have passed since the last dose of phenytoin at the time of the screening visit. If the phenytoin use was between 5-15 years before the screening visit and the patient received phenytoin for less than 2 months.
• Patients may be enrolled if they have been stabilized on the following therapy for the specified amount of time:

• Thyroid hormone (<0.1 mg/day thyroxine) therapy for at least 6 months. * Stable dosage of thiazide for at least 3 consecutive months.
• All patients must stop the following therapies at least 4 weeks prior to the screening visit and remain off these therapies for the remainder of the clinical trial. Screening laboratories must be performed after the washout is complete. However, imaging studies (BMD, X-rays) may be performed prior to starting the calcitonin, estrogen, and selective estrogen receptor modulation (SERM) washout.

• Calcitonin
• Estrogen replacement therapy by oral, transdermal or intramuscular administration
• SERM drugs, e.g., tamoxifen, raloxifene, Evista
• Vaginal application of estrogen-containing creams unless the dose is conjugated estrogen or estradiol* Cytostatics, e.g., azathioprine, recombinant human tumor necrosis fusion (Fc) protein, monoclonal antibody against tumor necrosis factor (e.g., remicade [infliximab])
• The drug class tetracyclines
• Medication known to affect the metabolism of bone (the Principal Investigator should discuss this with the Project Medical Officer before the patient is excluded from enrollment)

E. Miscellaneous Concurrent Medications:

• Methotrexate
• Intra-articular injections - Patients with chronic, active joint disease should be excluded from this Phase III study. Patients may receive a maximum of one intra-articular injection (ONE JOINT ONLY) every 6 months while participating in this Phase III study. The dose of corticosteroid injected should not exceed the anti-inflammatory equivalent dose of prednisone 40 mg suspension. The dose and volume should be adjusted downward as appropriate to the size of the joint.
• Provera is an acceptable concomitant medication when used according to the label instructions.

F. Laboratory Values and Physical Examination Findings:

• Serum calcium greater than 10.7 mg/dL (2.66 mmol/L). At screening, if the serum calcium is abnormal, the patient may have the additional evaluation described below ONCE:

• Discontinue all oral calcium and vitamin D3 supplements.
• Repeat a fasting serum calcium level two weeks later.
• If the fasting serum calcium level is still abnormal, the patient is discontinued from the study.
• If the repeat fasting serum calcium is normal, the patient should have supplemental calcium and vitamin D3 restarted at the time of study drug dosing, without going through a two-week stabilization period.
• Serum creatinine > 1.5 mg/dL (132.6 mmol/L)
• Urinary calcium to creatinine ratio is greater than or equal to 1. At screening, if a patient's urinary calcium to creatinine ratio is abnormal, the patient may have the additional evaluation described below ONCE:

• Discontinue all oral calcium and vitamin D3 supplements.
• Repeat a fasting urine calcium to creatinine ratio two weeks later.
• If the fasting urinary calcium to creatinine ratio is still abnormal, the patient is discontinued from the study.
• If the repeat fasting urinary calcium to creatinine ratio is normal, the patient should have supplemental calcium and vitamin D3 restarted at the time of study drug dosing, without going through a two-week stabilization period.
• Total serum alkaline phosphatase >130 U/L except as noted - Argentina (311 U/L); Brazil (278 U/L); Mexico (159 U/L).
• Any other clinically significant abnormal value as judged by the investigator
• Body weight below 40 kg

G. Substance Abuse:

• Alcohol and/or drug abuse

H. Psychiatric Disease:

• Current or history of psychiatric disease that would interfere with the ability to comply with the clinical trial protocol

I. Compliance:

• Suspected or confirmed poor compliance in completing clinical trial evaluations and/or clinical trial required questionnaires