Pharmacokinetic models for first-in-human dose selection of immune-activating products in oncology.

Pharmacokinetic (PK) models are increasingly submitted to the FDA to support first-in-human (FIH) dose selection of immune-oncology products. To examine whether a simple PK modeling (SPM) using clearance for scaling was acceptable for dose estimation, FIH(SPM) doses were computed and compared to doses that were safely administered to patients. We concluded that the SPM approach is acceptable in FIH dose estimation, but the variables should be carefully selected for CD3 constructs. For CD3 constructs, use of 60 kg BWh, a clearance exponent of 0.75, and a targeted plasma concentration based on relevant and/or sensitive activity assays was an acceptable approach for FIH dose selection; use of 0.85 as the scaling factor is questionable at this time as it resulted in a FIH dose that was too close to the AHD for one product (7%). Immune activating mAbs were not sensitive to changes in the clearance exponent (0.75-0.85) or body weight (60-70 kg). For PD-1/PD-L1 mAbs, using products' in vitro EC50 in the model resulted in suboptimal FIH doses and clinical data of closely related products informed FIH dose selection. PK models submitted by sponsors were diverse in methods, assumptions, and variables, and the resulting FIH doses were not always optimal.

Measuring ovarian toxicity in clinical trials: an American Society of Clinical Oncology research statement.

Anticancer agents can impair ovarian function, resulting in premature menopause and associated long-term health effects. Ovarian toxicity is not usually adequately assessed in trials of anticancer agents, leaving an important information gap for patients facing therapy choices. This American Society of Clinical Oncology (ASCO) statement provides information about the incorporation of ovarian toxicity measures in trial design. ASCO recommends: (1) measurement of ovarian toxicity in relevant clinical trials of anticancer agents that enrol post-pubertal, pre-menopausal patients; (2) collection of ovarian function measures at baseline and at 12-24 months after anticancer agent cessation, as a minimum, and later in line with the trial schedule; and (3) assessment of both clinical measures and biomarkers of ovarian function. ASCO recognises that routine measurement of ovarian toxicity and function in cancer clinical trials will add additional complexity and burden to trial resources but asserts that this issue is of such importance to patients that it cannot continue to be overlooked.

Trends in the approval of cancer therapies by the FDA in the twenty-first century.

The cancer treatment landscape has changed dramatically since the turn of the century, resulting in substantial improvements in outcomes for patients. This Review summarizes trends in the approval of oncology therapeutic products by the United States Food and Drug Administration (FDA) from January 2000 to October 2022, based on a categorization of these products by their mechanism of action and primary target. Notably, the rate of oncology indication approvals has increased in this time, driven by approvals for targeted therapies, as has the rate of introduction of new therapeutic approaches. Kinase inhibitors are the dominant product class by number of approved products and indications, yet immune checkpoint inhibitors have the second most approvals despite not entering the market until 2011. Other trends include a slight increase in the share of approvals for biomarker-defined populations and the emergence of tumour-site-agnostic approvals. Finally, we consider the implications of the trends for the future of oncology therapeutic product development, including the impact of novel therapeutic approaches and technologies.

An FDA analysis of clinical hold deficiencies affecting investigational new drug applications for oncology products.

A systematic analysis of new commercial investigational new drug applications (IND) submitted to the FDA's Office of Hematology and Oncology Products (OHOP) in the Center for Drug Evaluation and Research was conducted to quantify the most common reasons INDs for oncology indications go on clinical hold. In OHOP, less than 10% of INDs went on hold or were withdrawn within the 30-day safety review period. Of INDs that were placed on hold, deficiencies were mainly clinical, followed by concerns related to pharmaceutical quality and nonclinical development. INDs were also characterized based on phase of development, product type, sponsors' regulatory experience, and occurrence of a pre-IND meeting. INDs that were placed on hold were mostly for first-in-human trials or submitted by sponsors with limited regulatory experience. INDs that went on hold or were safe-to-proceed had pre-IND meetings with comparable rates but sponsors with substantial experience appeared to benefit more from pre-IND meetings compared to those with limited experience. The time interval between the pre-IND meeting and the IND submission was longer for INDs that went on hold. To obtain useful FDA feedback on product development, it is essential to provide focused questions and supporting information in pre-IND meeting packages.

An FDA oncology analysis of toxicities associated with PBD-containing antibody-drug conjugates.

With a new generation of antibody-drug conjugates (ADCs) that contain a drug-to-antibody ratio (DAR) of 2, the question remains whether advances in technology have resulted in more stable and tumor-specific ADCs. These ADCs are anticipated to cause minimal systemic exposures of payloads, with toxicities being evident mainly at tumor sites. We examined 15 ADCs with PBD-dimer payloads and a DAR of 2 and concluded that dose limiting toxicities in animals and in humans are generally related to the payload. Both the payloads and the ADCs had pro-inflammatory responses causing severe toxicities that were at times of low incidence, making it difficult to assess a cause-effect relationship. Due to their low incidence, single-patient cohorts may not detect these events and such design may not be suitable in first-in-human (FIH) trials. The commonly proposed approach by the sponsors for FIH dose selection was 1/6th highest non-severely toxic dose (HNSTD) in monkeys. This approach resulted in an acceptable balance of safety and efficient dose escalation in phase 1 trials, when using data from repeat-dose toxicology studies and body surface area for scaling. No sponsor used the data generated in rodents or proposed novel approaches for FIH dose selection.

An FDA oncology analysis of CD3 bispecific constructs and first-in-human dose selection.

We retrospectively examined the nonclinical studies conducted with 17 CD3 bispecific constructs in support of first-in-human (FIH) trials in oncology. We also collected information on the design of dose-finding clinical trials. Sponsors have used different MABEL approaches for FIH dose selection. To better assess acceptable approaches, FIH doses were computed from nonclinical studies and compared to the maximum tolerated doses (MTDs) in patients, to the highest human doses (HHDs) when an MTD was not identified, or to the recommended human dose (RHD) for blinatumomab. We concluded that approaches based on receptor occupancy, highest non-severely toxic dose, or no-observed adverse effect level are not acceptable for selecting the FIH dose as they resulted in doses close to or above the MTDs, HHDs, or the RHD. A FIH dose corresponding to 10%-30% pharmacologic activity (PA) was an acceptable approach. A FIH dose corresponding to 50% PA was acceptable for all except one construct, potentially due to its biological or structural properties. The most common toxicities in animals and patients were those related to cytokine release. Doses were better tolerated when intra-animal or intra-patient dose escalation was used. Exposing naïve patients to an MTD achieved with intra-patient dose escalation design may be unsafe.

An FDA oncology analysis of immune activating products and first-in-human dose selection.

As sub-therapeutic doses are not medically justifiable in patients with cancer, we retrospectively analyzed data on immune activating products, to assess approaches used in first-in-human (FIH) dose selection, the utility of animal toxicology studies in dose selection, and the length of time to complete FIH trials. The information collected included pharmacology and toxicology data, FIH dose and rationale, and dose-finding trial design. We used the principles of the Hill equation to estimate the FIH doses for antibodies and compared them to the doses administered to patients with acceptable toxicities. For approximately half the antibodies (44%) examined, the FIH doses were at least a hundred-fold lower than the doses safely administered to patients, indicating optimization of FIH dose selection and/or optimization of dose-finding trial design is needed to minimize patient exposure to sub-therapeutic doses. However, selection of the FIH dose for antibodies based on animal toxicology studies using 1/6th the HNSTD or 1/10th the NOAEL resulted in human doses that were unsafe for several antibodies examined. We also concluded that antibodies with Fc-modifications for increased effector function may be less tolerated, resulting in toxicities at lower doses than those without such modifications. There was insufficient information to evaluate CD3 bispecific products.

FDA Approval: Ibrutinib for Patients with Previously Treated Mantle Cell Lymphoma and Previously Treated Chronic Lymphocytic Leukemia.

On November 13, 2013, the FDA granted accelerated approval to ibrutinib (IMBRUVICA capsules; Pharmacyclics, Inc.) for the treatment of patients with mantle cell lymphoma (MCL) who have received at least one prior therapy. On February 12, 2014, the FDA granted accelerated approval for the treatment of patients with chronic lymphocytic leukemia (CLL) who have received at least one prior therapy. Ibrutinib is a first-in-class Bruton's tyrosine kinase (BTK) inhibitor that received all four expedited programs of the FDA: Fast-Track designation, Breakthrough Therapy designation, Priority Review, and Accelerated Approval. Both approvals were based on overall response rate (ORR) and duration of response (DOR) in single-arm clinical trials in patients with prior treatment. In MCL (N = 111), the complete and partial response rates were 17.1% and 48.6%, respectively, for an ORR of 65.8% [95% confidence interval (CI), 56.2%-74.5%]. The median DOR was 17.5 months (95% CI, 15.8-not reached). In CLL (N = 48), the ORR was 58.3% (95% CI, 43.2%-72.4%), and the DOR ranged from 5.6 to 24.2 months. The most common adverse reactions (≥ 30% in either trial) were thrombocytopenia, diarrhea, neutropenia, bruising, upper respiratory tract infection, anemia, fatigue, musculoskeletal pain, peripheral edema, and nausea.

FDA Approval: Belinostat for the Treatment of Patients with Relapsed or Refractory Peripheral T-cell Lymphoma.

On July 3, 2014, the FDA granted accelerated approval for belinostat (Beleodaq; Spectrum Pharmaceuticals, Inc.), a histone deacetylase inhibitor, for the treatment of patients with relapsed or refractory peripheral T-cell lymphoma (PTCL). A single-arm, open-label, multicenter, international trial in the indicated patient population was submitted in support of the application. Belinostat was administered intravenously at a dose of 1000 mg/m(2) over 30 minutes once daily on days 1 to 5 of a 21-day cycle. The primary efficacy endpoint was overall response rate (ORR) based on central radiology readings by an independent review committee. The ORR was 25.8% [95% confidence interval (CI), 18.3-34.6] in 120 patients that had confirmed diagnoses of PTCL by the Central Pathology Review Group. The complete and partial response rates were 10.8% (95% CI, 5.9-17.8) and 15.0% (95% CI, 9.1-22.7), respectively. The median duration of response, the key secondary efficacy endpoint, was 8.4 months (95% CI, 4.5-29.4). The most common adverse reactions (>25%) were nausea, fatigue, pyrexia, anemia, and vomiting. Grade 3/4 toxicities (≥5.0%) included anemia, thrombocytopenia, dyspnea, neutropenia, fatigue, and pneumonia. Belinostat is the third drug to receive accelerated approval for the treatment of relapsed or refractory PTCL.

An FDA oncology analysis of antibody-drug conjugates.

Antibody-drug conjugates (ADCs) are complex molecules composed of monoclonal antibodies conjugated to potent cytotoxic agents through chemical linkers. Because of this complexity, sponsors have used different approaches for the design of nonclinical studies to support the safety evaluation of ADCs and first-in-human (FIH) dose selection. We analyzed this data with the goal of describing the relationship between nonclinical study results and Phase 1 study outcomes. We summarized the following data from investigational new drug applications (INDs) for ADCs: plasma stability, animal study designs and toxicities, and algorithms used for FIH dose selection. Our review found that selecting a FIH dose that is 1/6th the highest non-severely toxic dose (HNSTD) in cynomolgus monkeys or 1/10th the STD10 in rodents scaled according to body surface area (BSA) generally resulted in the acceptable balance of safety and efficient dose-escalation in a Phase 1 trial. Other approaches may also be acceptable, e.g. 1/10th the HNSTD in monkeys using BSA or 1/10th the NOAEL in monkeys or rodents using body weight for scaling. While the animal data for the vc-MMAE platform yielded variable range of HNSTDs in cynomolgus monkeys, MTDs were in a narrow range in patients, suggesting that for ADCs sharing the same small molecule drug, linker and drug:antibody ratio, prior clinical data can inform the design of a Phase 1 clinical trial.

FDA approval: idelalisib monotherapy for the treatment of patients with follicular lymphoma and small lymphocytic lymphoma.

On July 23, 2014, the FDA granted accelerated approval to idelalisib (Zydelig tablets; Gilead Sciences, Inc.) for the treatment of patients with relapsed follicular B-cell non-Hodgkin lymphoma or relapsed small lymphocytic lymphoma (SLL) who have received at least two prior systemic therapies. In a multicenter, single-arm trial, 123 patients with relapsed indolent non-Hodgkin lymphomas received idelalisib, 150 mg orally twice daily. In patients with follicular lymphoma, the overall response rate (ORR) was 54%, and the median duration of response (DOR) was not evaluable; median follow-up was 8.1 months. In patients with SLL, the ORR was 58% and the median DOR was 11.9 months. One-half of patients experienced a serious adverse reaction of pneumonia, pyrexia, sepsis, febrile neutropenia, diarrhea, or pneumonitis. Other common adverse reactions were abdominal pain, nausea, fatigue, cough, dyspnea, and rash. Common treatment-emergent laboratory abnormalities were elevations in alanine aminotransferase, aspartate aminotransferase, gamma-glutamyltransferase, absolute lymphocytes, and triglycerides. Continued approval may be contingent upon verification of clinical benefit in confirmatory trials.

FDA approval: siltuximab for the treatment of patients with multicentric Castleman disease.

On April 22, 2014, the FDA granted full approval to siltuximab (SYLVANT for injection; Janssen Biotech, Inc.), a chimeric human-mouse monoclonal antibody to IL6, for the treatment of patients with multicentric Castleman disease (MCD) who are human immunodeficiency virus (HIV) negative and human herpesvirus-8 (HHV-8) negative. The approval was primarily based on the results of a randomized, double-blind trial in which 79 symptomatic patients with MCD were allocated (2:1) to siltuximab plus best supportive care (BSC) or to placebo plus BSC. The primary efficacy endpoint was the proportion of patients in each arm achieving a durable tumor and symptomatic response that persisted for a minimum of 18 weeks without treatment failure. Tumor response was based on independent review of CT scans using the revised Response Criteria for Malignant Lymphoma, and symptomatic response was defined as complete resolution or stabilization of 34 MCD-related signs and symptoms as reported by the investigator. Thirty-four percent of patients in the siltuximab arm and no patients in the placebo arm met the primary endpoint (P = 0.0012). The most common adverse reactions (>10% compared with placebo) during treatment with siltuximab were pruritus, increased weight, rash, hyperuricemia, and upper respiratory tract infection.

U.S. Food and drug administration approval: obinutuzumab in combination with chlorambucil for the treatment of previously untreated chronic lymphocytic leukemia.

On November 1, 2013, the U.S. Food and Drug Administration (FDA) approved obinutuzumab (GAZYVA; Genentech, Inc.), a CD20-directed cytolytic antibody, for use in combination with chlorambucil for the treatment of patients with previously untreated chronic lymphocytic leukemia (CLL). In stage 1 of the trial supporting approval, patients with previously untreated CD20-positive CLL were randomly allocated (2:2:1) to obinutuzumab + chlorambucil (GClb, n = 238), rituximab + chlorambucil (RClb, n = 233), or chlorambucil alone (Clb, n = 118). The primary endpoint was progression-free survival (PFS), and secondary endpoints included overall response rate (ORR). Only the comparison of GClb to Clb was relevant to this approval and is described herein. A clinically meaningful and statistically significant improvement in PFS with medians of 23.0 and 11.1 months was observed in the GClb and Clb arms, respectively (HR, 0.16; 95% CI, 0.11-0.24; P < 0.0001, log-rank test). The ORRs were 75.9% and 32.1% in the GClb and Clb arms, respectively, and the complete response rates were 27.8% and 0.9% in the GClb and Clb arms, respectively. The most common adverse reactions (≥10%) reported in the GClb arm were infusion reactions, neutropenia, thrombocytopenia, anemia, pyrexia, cough, and musculoskeletal disorders. Obinutuzumab was the first Breakthrough Therapy-designated drug to receive FDA approval.

U.S. Food and Drug Administration approval summary: omacetaxine mepesuccinate as treatment for chronic myeloid leukemia.

On October 26, 2012, the U.S. Food and Drug Administration (FDA) granted accelerated approval to omacetaxine mepesuccinate (Synribo; Teva Pharmaceuticals USA, Inc., North Wales, PA, http://www.tevausa.com) for the treatment of adult patients with chronic phase (CP) or accelerated phase (AP) chronic myeloid leukemia (CML) with resistance and/or intolerance to two or more tyrosine kinase inhibitors (TKIs). The approval was based on the FDA review of data from 111 patients with CML in CP or in AP who had received two or more prior TKIs, including imatinib. Major cytogenetic response was achieved in 18% of patients with CP, with a median response duration of 12.5 months. Major hematologic response was achieved in 14% of patients with AP, with a median response duration of 4.7 months. The FDA safety evaluation was based on submitted data from 163 patients with CP or AP CML who had received at least one dose of omacetaxine mepesuccinate. The safety evaluation was limited by the single-arm design of the clinical trials as conducted in a small number of previously treated patients. The most common (≥20%) adverse reactions of any grade in enrolled patients included thrombocytopenia, anemia, neutropenia, diarrhea, nausea, fatigue, asthenia, injection site reaction, pyrexia, and infection. The FDA concluded that omacetaxine mepesuccinate has shown activity and a favorable benefit-to-risk profile for the studied population of adult patients with CML (CP or AP) with resistance and/or intolerance to two or more TKIs. Further evidence of response durability to verify clinical benefit is pending.

U.S. Food and Drug Administration approval summary: brentuximab vedotin for the treatment of relapsed Hodgkin lymphoma or relapsed systemic anaplastic large-cell lymphoma.

The U.S. Food and Drug Administration (FDA) describes the accelerated approval of brentuximab vedotin for patients with relapsed Hodgkin lymphoma and relapsed systemic anaplastic large-cell lymphoma (sALCL). FDA analyzed the results of two single-arm trials, enrolling 102 patients with Hodgkin lymphoma and 58 patients with sALCL. Both trials had primary endpoints of objective response rate (ORR) and key secondary endpoints of response duration and complete response (CR) rate. For patients with Hodgkin lymphoma, ORR was 73% (95% CI, 65-83%); median response duration was 6.7 months, and CR was 32% (95% CI, 23-42%). For patients with sALCL, ORR was 86% (95% CI, 77-95%), median response duration was 12.6 months, and CR was 57% (95% CI, 44-70%). The most common adverse reactions were neutropenia, peripheral sensory neuropathy, fatigue, nausea, anemia, upper respiratory infection, diarrhea, pyrexia, rash, thrombocytopenia, cough, and vomiting. FDA granted accelerated approval of brentuximab vedotin for the treatment of patients with Hodgkin lymphoma after failure of autologous stem cell transplantation (ASCT) or after failure of at least two prior multiagent chemotherapy regimens in patients who are not ASCT candidates, and for the treatment of patients with sALCL after failure of at least one prior multiagent chemotherapy regimen.

U.S. Food and Drug Administration approval: ruxolitinib for the treatment of patients with intermediate and high-risk myelofibrosis.

On November 16, 2011, the U.S. Food and Drug Administration (FDA) granted full approval to ruxolitinib, (Jakafi; Incyte Corp.), an inhibitor of the Janus kinases 1 and 2, for the treatment of patients with intermediate- or high-risk myelofibrosis, including primary myelofibrosis, postpolycythemia vera myelofibrosis, and postessential thrombocythemia myelofibrosis. This approval was based on the results of 2 large randomized phase III trials that enrolled patients with intermediate-2 or high-risk myelofibrosis and compared ruxolitinib with placebo (study 1) or best available therapy (study 2). The primary efficacy endpoint was the proportion of patients who experienced a reduction in spleen volume of ≥ 35% at 24 weeks (study 1) or 48 weeks (study 2). The key secondary endpoint in study 1 was the proportion of patients who experienced a ≥ 50% improvement from baseline in myelofibrosis total symptom score at 24 weeks. The results of these studies showed that a greater proportion of patients treated with ruxolitinib experienced a ≥ 35% reduction in spleen volume as compared with those treated with placebo (42% vs. 1%, P < 0.0001) or best available therapy (29% vs. 0%, P < 0.0001). A greater proportion of patients in study 1 experienced a ≥ 50% reduction in the myelofibrosis total symptom score during treatment with ruxolitinib than with placebo (46% vs. 5%, P < 0.0001). Ruxolitinib treatment was associated with an increased incidence of grades III and IV anemia, thrombocytopenia, and neutropenia. This is the first drug approved for myelofibrosis.

FDA review summary: Mozobil in combination with granulocyte colony-stimulating factor to mobilize hematopoietic stem cells to the peripheral blood for collection and subsequent autologous transplantation.

PURPOSE: On December 15, 2008, the US Food and Drug Administration approved plerixafor (Mozobil; Genzyme Corp.), a new small-molecule inhibitor of the CXCR4 chemokine receptor, for use in combination with granulocyte colony-stimulating factor (G-CSF) to mobilize hematopoietic stem cells (HSC) to the peripheral blood for collection and subsequent autologous transplantation in patients with non-Hodgkin's lymphoma (NHL) and multiple myeloma (MM). This summary reviews the database supporting this approval. EXPERIMENTAL DESIGN: The safety and efficacy of plerixafor were demonstrated by 2 multicenter, randomized, placebo-controlled studies in patients with NHL and MM who were eligible for autologous HSC transplantation. The primary efficacy end points were the collection of > or = 5 x 10(6) CD34+ cells/kg from the peripheral blood in 4 or fewer apheresis sessions in patients with NHL or > or = 6 x 10(6) CD34+ cells/kg from the peripheral blood in 2 or fewer apheresis sessions in patients with MM. RESULTS: The 2 randomized studies combined enrolled 600 patients (298 with NHL and 302 with MM). Fifty-nine percent of patients with NHL who were mobilized with G-CSF and plerixafor had peripheral blood HSC collections of > or = 5 x 10(6) CD34+ cells/kg in 4 or fewer apheresis sessions, compared with 20% of patients with NHL who were mobilized with G-CSF and placebo (p < 0.001). Seventy-two percent of patients with MM who were mobilized with Mozobil and G-CSF had peripheral blood HSC collections of > or = 6 x 10(6) CD34+ cells/kg in 2 or fewer apheresis sessions, compared with 34% of patients with MM who were mobilized with placebo and G-CSF (p < 0.001). Common adverse reactions included diarrhea, nausea, vomiting, flatulence, injection site reactions, fatigue, arthralgia, headache, dizziness, and insomnia. CONCLUSIONS: This report describes the Food and Drug Administration review supporting the approval of plerixafor.

Sprycel for chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia resistant to or intolerant of imatinib mesylate.

PURPOSE: On June 28, 2006, the U.S. Food and Drug Administration approved dasatinib (Sprycel; Bristol-Myers Squibb), a new small-molecule inhibitor of multiple tyrosine kinases, for the treatment of adults with chronic phase, accelerated phase, or myeloid or lymphoid blast phase chronic myeloid leukemia (CML) or Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+) ALL) with resistance or intolerance to prior therapy including imatinib. This summary reviews the database supporting this approval. EXPERIMENTAL DESIGN: Four single-arm multicenter studies supported the efficacy and safety of dasatinib. The primary efficacy end point in chronic phase CML was major cytogenetic response. The primary end point in accelerated phase, myeloid phase, and lymphoid blast phase CML, and Ph(+) ALL was major hematologic response. RESULTS: The four studies combined enrolled 445 patients. In patients with chronic phase CML, the major cytogenetic response rate was 45% with a complete cytogenetic response rate of 33%. Major hematologic response rates in patients with accelerated phase CML, myeloid CML, lymphoid blast CML, and Ph(+) ALL were 59%, 32%, 31%, and 42%, respectively. Median response durations in chronic phase, accelerated phase, and myeloid phase CML had not been reached. The median durations of major hematologic response were 3.7 months in lymphoid blast CML and 4.8 months in Ph(+) ALL. Common toxicities with dasatinib included myelosuppression, bleeding, and fluid retention. CONCLUSIONS: This report describes the Food and Drug Administration review supporting the approval of dasatinib for CML and Ph(+) ALL based on the rates and durability of cytogenetic and hematologic responses.