2.1. Recommended Dosage

The recommended dosage of RYTELO is 7.1 mg/kg administered as an intravenous infusion over 2 hours every 4 weeks. Discontinue RYTELO if a patient does not experience a decrease in red blood cell (RBC) transfusion burden after 24 weeks of treatment (administration of 6 doses) or if unacceptable toxicity occurs at any time [see Dosage and Administration (2.3)].

2.2. Recommended Premedications

Administer the following pre-treatment medications at least 30 minutes prior to dosing to prevent or reduce potential infusion-related reactions:

• diphenhydramine (or equivalent) 25 mg to 50 mg, intravenously or orally
• hydrocortisone (or equivalent) 100 mg to 200 mg, intravenously or orally

Monitor patients for adverse reactions for at least one hour after the infusion has been completed [see Warnings and Precautions (5.3) and Adverse Reactions (6.1)].

2.3. Dosage Modifications for Adverse Reactions

Recommended dose reductions for Grade 3 and Grade 4 adverse reactions are found in Table 1.

The management of Grade 3 and Grade 4 adverse reactions may require temporary dose delay, dose reduction, or treatment discontinuation and are presented in Table 2 and Table 3. RYTELO treatment should be permanently discontinued if the patient cannot tolerate the lowest dose level of 4.4 mg/kg.

2.4. Preparation and Administration

RYTELO is provided as a lyophilized powder in a single-dose vial for intravenous infusion only and must be reconstituted and diluted prior to administration.

Use aseptic technique to prepare RYTELO.

RYTELO does not contain a preservative.

5.1. Thrombocytopenia

RYTELO can cause thrombocytopenia based on laboratory values. In the clinical trial, new or worsening Grade 3 or 4 decreased platelets occurred in 65% of patients with MDS treated with RYTELO [see Adverse Reactions (6.1)].

Median time to onset of first occurrence of Grade 3 or 4 decreased platelets was 6 weeks (range: 2 to 88 weeks) and median time to recovery from each occurrence of Grade 3 or 4 decreased platelets to Grade 2 or lower, or last value available, was 1.3 weeks (range: 0.1 to 13 weeks). Grade 3 or 4 decreased platelets occurred throughout treatment with RYTELO, with 48% of patients experiencing Grade 3 or Grade 4 thrombocytopenia during cycles 1-3, 31% during cycles 4-6, 33% during cycles 7-12, and 24% during cycles 13 and beyond. Grade 3 or 4 bleeding was seen in 2.5% of patients, including gastrointestinal bleeding (1.7%) and hematuria (0.8%).

Monitor patients with thrombocytopenia for bleeding.

Monitor complete blood cell counts prior to initiation of RYTELO, weekly for the first two cycles, prior to each cycle thereafter, and as clinically indicated. Administer platelet transfusions as appropriate. Delay the next cycle and resume at the same or reduced dose, or discontinue as recommended [see Dosage and Administration (2.3)].

5.2. Neutropenia

RYTELO can cause neutropenia based on laboratory values. In the clinical trial, new or worsening Grade 3 or 4 decreased neutrophils occurred in 72% of patients with MDS treated with RYTELO [see Adverse Reactions (6.1)].

Median time to onset of first occurrence of Grade 3 or 4 decreased neutrophils was 4.6 weeks (range: 1 to 81 weeks) and median time to recovery from each occurrence of Grade 3 or 4 decreased neutrophils to Grade 2 or lower, or last value available, was 1.9 weeks (range: 0 to 16 weeks). Grade 3 or 4 decreased neutrophils occurred throughout treatment with RYTELO, with 65% of patients experiencing Grade 3 or Grade 4 neutropenia during cycles 1-3, 35% during cycles 4-6, 32% during cycles 7-12, and 39% during cycles 13 and beyond. Febrile neutropenia occurred in 0.8% and sepsis in 4.2%.

Monitor patients with Grade 3 or 4 neutropenia for infections, including sepsis.

Monitor complete blood cell counts prior to initiation of RYTELO, weekly for the first two cycles, prior to each cycle thereafter, and as clinically indicated. Administer growth factors and anti-infective therapies for treatment or prophylaxis as appropriate. Delay the next cycle and resume at the same or reduced dose, or discontinue as recommended [see Dosage and Administration (2.3)].

5.3. Infusion-Related Reactions

RYTELO can cause infusion-related reactions. In the clinical trial, infusion-related reactions occurred in 8% of patients with MDS treated with RYTELO; Grade 3 or 4 infusion-related reactions occurred in 1.7%, including hypertensive crisis (0.8%). The most common infusion-related reaction was headache (4.2%). Infusion-related reactions usually occur during or shortly after the end of the infusion.

Premedicate patients at least 30 minutes prior to infusion with diphenhydramine and hydrocortisone as recommended and monitor patients for at least one hour following the infusion as recommended [see Dosage and Administration (2.2)]. Manage symptoms of infusion-related reactions with supportive care and infusion interruptions, decrease infusion rate, or permanently discontinue as recommended [see Dosage and Administration (2.3)].

5.4. Embryo-Fetal Toxicity

Based on findings in animals, RYTELO can cause embryo-fetal harm when administered to a pregnant woman. In animal reproduction studies, administration of imetelstat to pregnant mice during the period of organogenesis resulted in embryo-fetal mortality at maternal exposures (AUC) 2.5-times the human exposure at the recommended clinical dose. Advise pregnant women of the potential risk to a fetus. Advise females of reproductive potential to use effective contraception during treatment with RYTELO and for 1 week after the last dose [see Use in Specific Populations (8.1, 8.3)].

6.1. Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

8.1. Pregnancy

8.2. Lactation

8.3. Females and Males of Reproductive Potential

Based on findings from animal studies, RYTELO can cause embryo-fetal harm when administered to a pregnant woman [see Use in Specific Populations (8.1)].

8.4. Pediatric Use

Safety and effectiveness of RYTELO in pediatric patients have not been established.

8.5. Geriatric Use

Of the 118 patients with low- to intermediate-1 risk myelodysplastic syndromes (MDS) in the clinical trial who received RYTELO, 91 (77.1%) patients were 65 years of age and older and 35 (29.7%) patients 75 years of age and older. No differences in safety or efficacy were observed between older (≥ 65 years) and younger patients.

12.1. Mechanism of Action

Imetelstat is an oligonucleotide human telomerase inhibitor that binds to the template region of the RNA component of human telomerase (hTR), inhibits telomerase enzymatic activity and prevents telomere binding.

Increased telomerase activity and human telomerase reverse transcriptase (hTERT) RNA expression have been reported in MDS and malignant stem and progenitor cells. Nonclinical studies showed imetelstat treatment led to reduction of telomere length, reduction of malignant stem and progenitor cell proliferation, and induction of apoptotic cell death.

12.2. Pharmacodynamics

12.3. Pharmacokinetics

Imetelstat plasma geometric mean (coefficient of variation [CV] %) maximum concentration (Cmax) is 18.3 µM (27.3%) and the area under the concentration-time curve from time 0 to 28 days (AUC0-28) was 114.2 h*µM (43.2%). Imetelstat does not accumulate between treatment cycles.

12.6. Immunogenicity

The observed incidence of anti-drug antibodies (ADA) is highly dependent on the sensitivity and specificity of the assay. Differences in assay methods preclude meaningful comparisons of the incidence of anti-drug antibodies in the studies described below with the incidence of anti-drug antibodies in other studies, including those of RYTELO.

Seventeen percent (28/166) of evaluable patients with low- or intermediate-1 risk MDS tested positive for imetelstat anti-drug antibodies, with a median onset of 38 weeks following the study drug dosage of RYTELO for a median duration of treatment of 35 weeks in Phase 2 and Phase 3 of the IMerge study. There was no clinically significant effect of ADA on the PK, safety, or efficacy of RYTELO among the study participants who developed anti-drug antibodies.

13.1. Carcinogenesis, Mutagenesis, Impairment of Fertility

Carcinogenicity studies have not been conducted with imetelstat.

In vitro, imetelstat was not mutagenic in the bacterial mutagenicity assay (Ames test) or clastogenic in the chromosomal aberrations assay using cultured human peripheral blood lymphocytes. Imetelstat was not genotoxic in an in vivo mouse micronucleus assay at intravenous dose levels up to approximately 104 mg/kg.

Fertility studies have not been conducted with imetelstat. Female monkeys given 14.1 mg/kg once weekly for 9 months exhibited uterine endometrial atrophy in a general toxicology study. This effect was observed at a mean exposure (based on AUC) that is approximately 14.4-times the human exposure at the recommended clinical dose. This finding was not present in animals following a 14-week recovery period.

14.1. Myelodysplastic Syndromes (MDS)

The efficacy of RYTELO was evaluated in a randomized, double-blind, placebo-controlled, multicenter trial (IMerge; NCT02598661) in 178 patients enrolled with International Prognostic Scoring System (IPSS) low- or intermediate-1 risk MDS who were transfusion-dependent (requiring ≥ 4 red blood cell (RBC) units over an 8-week period during the 16 weeks prior to randomization). Eligible patients were required to have failed to respond or have lost response or be ineligible for erythropoiesis-stimulating agents (ESAs); and had an absolute neutrophil count of 1.5 × 109/L or greater and platelets 75 × 109/L or greater. Patients were ineligible if they had del(5q) cytogenetic abnormality or had received prior treatment with lenalidomide or hypomethylating agents.

Participants were randomized in a 2:1 ratio to receive an intravenous infusion of RYTELO (n=118) 7.1 mg/kg or placebo (n=60) in 28-day treatment cycles until disease progression, unacceptable toxicity, or withdrawal from the study. Randomization was stratified by prior RBC transfusion burden and by IPSS risk group. All patients received supportive care, which included RBC transfusions.

Of the 178 patients enrolled, the median age was 72 years (range: 39 to 87 years), with 62% male, and 80% White, 6% Asian, 1.7% Black, 12% other or not reported. The key baseline disease characteristics of the efficacy population are shown in Table 7.

Efficacy was established after a median follow up time of 19.5 months (range: 1.4 to 36.2) in the imetelstat group and 17.5 months (range: 0.7 to 34.3) in the placebo group based upon the proportion of patients who achieved ≥ 8-week and ≥ 24-week RBC-TI, defined as the absence of RBC transfusion(s) during any consecutive 8 weeks (56 days) period, and during any consecutive 24 weeks (168 days) period, respectively, from randomization until the start of subsequent anti-cancer therapy (if any). The efficacy results are summarized in Table 8.

How Supplied

RYTELO (imetelstat) for injection is a preservative free, white to off-white or slightly yellow, lyophilized powder available as:

Storage

Store vials refrigerated at 2°C to 8°C (36°F to 46°F) in original carton.

Do not freeze.

Thrombocytopenia

Advise patients of the risk of thrombocytopenia with RYTELO, and that their blood counts will be monitored routinely while on treatment and dose of RYTELO delayed or reduced as needed. Instruct patients to notify a healthcare provider immediately if they show signs or symptoms of thrombocytopenia such as unusual bleeding or bruising [see Warnings and Precautions (5.1)].

Neutropenia

Advise patients of the risk of neutropenia with RYTELO and that their blood counts will be monitored routinely while on treatment and the dose of RYTELO may be delayed or reduced as needed. Instruct patients to notify a healthcare provider immediately if they show signs or symptoms of neutropenia, such as fever or infection [see Warnings and Precautions (5.2)].

Infusion-Related Reactions

Inform patients that infusion-related reactions can occur during treatment with RYTELO and premedications will be given prior to each infusion. Patients will be monitored by their healthcare provider for at least an hour after the infusion [see Dosage and Administration (2.2) and Warnings and Precautions (5.3)].

Advise patients that their healthcare provider may decide to give RYTELO more slowly or stop the infusion if an infusion-related reaction occurs [see Adverse Reactions (6.1)]

Embryo-Fetal Toxicity

Advise pregnant women and females of reproductive potential of the potential risk to a fetus. Advise females of reproductive potential to inform their healthcare provider if they are pregnant or become pregnant [see Warnings and Precautions (5.4) and Use in Specific Populations (8.1)]. Advise females of reproductive potential to use effective contraception during treatment with RYTELO and for 1 week after the last dose [see Use in Specific Populations (8.3)].

Lactation

Advise women not to breastfeed during treatment with RYTELO and for 1 week after the last dose [see Use in Specific Populations (8.2)].