Abstract CT198: Subcutaneous delivery of amivantamab in patients with advanced solid malignancies: Initial safety and pharmacokinetic results from the PALOMA study

Background: Amivantamab, an epidermal growth factor receptor (EGFR)-MET bispecific antibody, is approved for patients with advanced EGFR exon 20 insertion non-small cell lung cancer after progression on platinum-based chemotherapy. First-dose intravenous (IV) delivery leads to infusion-related reactions (IRR) among 66% of patients, resulting in dose interruptions and slower infusion restart rates (infusion duration ranges 2-4 hours) and necessitates splitting of the dose over 2 days (Park Ann Oncol 32[suppl_5]:S981). Subcutaneous (SC) administration of amivantamab, which could simplify and accelerate administration, is being investigated in an ongoing phase 1 study (PALOMA; NCT04606381). Preliminary safety (including IRR) and pharmacokinetics (PK) of SC formulations of amivantamab ± recombinant human hyaluronidase (rHuPH20) for enhanced absorption were evaluated.

Methods: PALOMA is an ongoing phase 1 dose escalation study of amivantamab SC in patients with advanced solid tumors who may derive benefit from EGFR or MET-directed therapy. Eligible patients must have progressed after standard-of-care therapy for metastatic disease, be ineligible for, or have declined current standard therapies. The study objectives were to evaluate the feasibility of administration, safety, and PK of a low concentration formulation, 50 mg/mL of amivantamab ± rHuPH20 (Part 1) and a high concentration formulation, 160 mg/mL of amivantamab ± rHuPH20 (Part 2). Patients in Part 1 and Part 2 received the currently approved dosage of amivantamab, 1050 mg (1400 mg for bodyweight ≥80 kg) SC (weekly for the first 4 weeks and every other week thereafter). This study also evaluated administering the full dose of amivantamab on the first day.

Results: The full safety, PK, bioavailability, and receptor occupancy data of patients enrolled in Part 1 (n=16) and Part 2 (n=17) will be presented. Compared to IV administration, initial SC experience demonstrates the co-formulation of high concentration amivantamab with rHuPH20 shortened the needed infusion time to less than 5 minutes, with initial bioavailability of approximately 65% of IV administration. Saturation of soluble free EGFR and MET was achieved after the first SC dose. The incidence of IRRs was 18.2%, with all events of grade 1-2 severity. The full amivantamab SC dose was safely given at first administration to 14 patients, potentially obviating the need for split dosing.

Conclusions: Initial SC amivantamab ± rHuPH20 was well tolerated with improvements in time and ease of administration and associated with a meaningful reduction in IRRs, eliminating the need for split dosing compared with IV administration. Higher SC dose levels and alternative dosing schedules are being explored.

Citation Format: Matthew G. Krebs, Melissa L. Johnson, Byoung Chul Cho, Se-Hoon Lee, Rachel Kudgus-Lokken, Donna Zemlickis, Anna Mitselos, Eileen Berkay, Joshua M. Bauml, Roland E. Knoblauch, Peter Hellemans, Anna Minchom. Subcutaneous delivery of amivantamab in patients with advanced solid malignancies: Initial safety and pharmacokinetic results from the PALOMA study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT198.

Subcutaneous delivery of amivantamab in patients with advanced solid malignancies: PALOMA, an open-label, multicenter, dose escalation phase 1b study

TPS3150

Background: Amivantamab, an epidermal growth factor receptor (EGFR)-MET bispecific antibody with immune cell-directing activity, targets activating/resistance EGFR mutations and MET mutations/amplifications. Amivantamab has demonstrated antitumor activity in patients (pts) with EGFR-mutant NSCLC and also in pts with EGFR tyrosine kinase inhibitor-resistant disease. The recommended phase 2 dose (RP2D) is 1050 mg (1400 mg, ≥80 kg) administered as intravenous (IV) infusions weekly (QW) for the first 28-day cycle and every other week (Q2W) thereafter. A subcutaneous (SC) formulation of amivantamab has the potential to reduce pt and physician burden by reducing administration time. The safety and pharmacokinetics (PK) of amivantamab administered SC ± recombinant human hyaluronidase (rHuPH20) will be evaluated. Methods: PALOMA is an ongoing phase 1b dose escalation study of amivantamab SC in pts with advanced solid tumors that may derive benefit from EGFR or MET-directed therapy (NCT04606381). Pts must have progressed on standard of care therapy for metastatic disease, be ineligible for, or have refused current standard therapies. The primary endpoints are trough concentration at the end of QW dosing and safety of SC administration. The objective of part 1 is to evaluate the feasibility, safety, and PK of SC administration of a low concentration (50 mg/mL) formulation of amivantamab alone (Ami-LC) or admixed with rHuPH20 (Ami-LC-MD). Approximately 8 pts will be enrolled to receive either 1050/1400 mg amivantamab SC using Ami-LC-MD (Cohort 1a) or Ami-LC (Cohort 1b) QW in cycle 1 and Q2W thereafter. The objective of part 2 is to evaluate the safety and PK of SC administration of a high concentration (160 mg/mL) formulation of amivantamab alone (Ami-HC) or with rHuPH20 (Ami-HC-CF) and to determine a dose, schedule, and formulation for SC administration that achieves similar exposure as observed at the RP2D of amivantamab IV, with acceptable safety. Pts enrolled in part 2 will initially receive 1050/1400 mg amivantamab SC using Ami-HC-CF in Cohort 2a or Ami-HC in Cohort 2b. ≤10 pts may be enrolled in either cohort. Additional cohorts of ≤10 pts may be enrolled to support dose, schedule, and formulation selection as guided by safety and PK observations in earlier cohorts. To mitigate infusion related reactions (IRR), medication with steroid, paracetamol, and antihistamine will be given pre-infusion and as clinically indicated post-infusion. Safety assessments include monitoring adverse events, laboratory abnormalities, vital signs, IRR, and injection site reactions. Blood samples will be collected to assess PK, pharmacodynamics, and immunogenicity. A Study Evaluation Team composed of investigators and sponsor representatives will review safety and PK data to make decisions about dose escalation and cohort expansion throughout the conduct of the study. Clinical trial information: NCT04606381.

Corticosteriod tapering in patients (Pts) with relapsed or refractory multiple myeloma (RRMM) receiving subcutaneous daratumumab (DARA SC): Part 3 of the open-label, multicenter, phase Ib PAVO Study

8537

Background: Intravenous DARA (DARA IV) is approved for the treatment of MM. In Part 2 of PAVO, DARA SC, a concentrated, pre-mixed SC co-formulation of DARA and recombinant human hyaluronidase PH20 (rHuPH20), was well tolerated, with a low infusion-related reaction (IRR) rate, and showed consistent serum concentrations and similar efficacy to DARA IV in RRMM pts. In PAVO Part 3, we evaluated the safety of pre- and post-dose corticosteroid tapering during DARA SC administration. Methods: RRMM pts with ≥2 prior lines of treatment, including a proteasome inhibitor (PI) and immunomodulatory drug (IMiD), received DARA SC (DARA 1,800 mg + rHuPH20 30,000 U in 15 mL) by manual SC injection per approved IV monotherapy dosing schedule. Pts received a 3-week (wk) tapering schedule (corticosteroid-free by Cycle [C] 1 Day [D] 22), with methylprednisolone (MP) given PO/IV pre-dose (C1D1, 100 mg; C1D8, 60 mg; C1D15, 30 mg) and PO post-dose (C1D1, 20 mg for 2 days; C1D8, 20 mg for 1 day; C1D15, 20 mg for 1 day), or a 2-wk tapering schedule (corticosteroid-free by C1D15), with MP given PO/IV pre-dose (C1D1, 100 mg; C1D8, 60 mg) and PO post-dose (C1D1, 20 mg for 2 days; C1D8, 20 mg for 1 day). Results: Pts (3-wk group, n = 15; 2-wk group, n = 15) received a median of 2 (range: 2-7) prior lines of therapy, with 37% refractory to a PI and an IMiD. The 3-wk and 2-wk groups received a median (range) of 14 (2-19+) and 8 (2-16+) DARA SC doses without corticosteroids, respectively. No IRRs were reported in the 3-wk group. 3 pts (20%) in the 2-wk group experienced IRRs on C1D1 (grade 3 hypertension, grade 2 chills, grade 1 pyrexia, grade 1 oropharyngeal pain, and grade 1 tachycardia). IRRs occurred within 2 h of the first DARA SC administration; no IRRs were reported at later administrations. Most common (≥25%) treatment emergent adverse events (TEAEs) were upper respiratory tract infection (40%) and fatigue and nausea (27% each). Most common (≥5%) grade 3/4 TEAEs were anaemia, lymphopenia, neutropenia, and hypertension (7% each). At median follow-up of 6.8 mo (3-wk group) and 2.4 mo (2-wk group), the overall response rates were 40% (95% CI, 16-68%) and 27% (95% CI, 8-55%) and ≥very good partial response rates were 13% (95% CI, 2-40%) and 7% (95% CI, 0-32%), respectively. Conclusions: Rapid corticosteroid tapering over 2 wks is safe in RRMM pts receiving DARA SC. These data help guide future DARA SC combinations (ie, T-cell redirectors, CAR-T, or checkpoint inhibitors), where limiting concurrent corticosteroids may be preferred. Clinical trial information: NCT02519452 .

Non-Hodgkin's lymphoma and pregnancy

Non-Hodgkin's lymphoma (NHL) is infrequently diagnosed during pregnancy. Most NHL's complicating pregnancy are aggressive and disseminated. This presentation together with the possible teratogenecity of diagnostic methods dictate a limited staging workup during pregnancy. Although prognosis had been reported to be poor, there is recent evidence to suggest that when properly treated, pregnancy does not affect the course of lymphoma. The risk to the fetus can also be reduced by an appropriate therapeutic approach.

Cisplatin protein binding in pregnancy and the neonatal period

The most effective combination regimes for ovarian cancer contain cisplatin, but there is little knowledge about cisplatin use during pregnancy. The high protein binding of cisplatin means that small changes in protein binding result in large changes in the fraction of free drug. It is the free form of cisplatin that crosses the placenta and may contribute to fetal toxicity. The purpose of the present study was to compare protein binding of cisplatin in pregnant women, non-pregnant women, and newborn infants. We found that babies and pregnant women had significantly lower concentrations of both protein and albumin compared to non-pregnant women. Analysis of variance found overall significant differences in protein binding among the three groups over time (P < .05). Babies had statistically less cisplatin protein binding than non-pregnant women at 80 minutes and all time points thereafter (P < .05). In contrast, pregnant women had statistically less cisplatin protein binding than non-pregnant women at 3.3 and 8 hours (P < .05). Of interest, at 75.2 hours, the percentage of free cisplatin was 15% in babies as compared with 9% in non-pregnant women and 10% in pregnant women. This means that the fetus is exposed to 50% higher platinum levels at equal total concentration. Cisplatin protein binding significantly correlated with albumin concentrations at 3.3, 8, and 24 hours (P < .01). Our analysis reveals that pregnancy and fetal changes in cisplatin protein binding are caused in large part by lower albumin levels. The resulting higher levels of free drug in the mother and fetus may increase the risk of toxicity in both.

Teratogenicity and carcinogenicity in a twin exposed in utero to cyclophosphamide

A 29-year-old pregnant woman diagnosed with acute lymphocytic leukemia maintained remission with daily cyclophosphamide and intermittent prednisone treatment. She delivered a male twin with multiple congenital abnormalities who was diagnosed with papillary thyroid cancer at 11 years of age and stage III neuroblastoma at 14 years of age. The female twin was unaffected and has exhibited normal development to date. First trimester exposure to cyclophosphamide has been associated with major malformations. Metabolites of cyclophosphamide have been demonstrated to be teratogens and carcinogens in animals. Differences in placental or fetal hepatic cytochrome P-450 may account for the variability in response between the twins. In addition, disparity between the twins may be the result of differences in metabolite inactivating enzymes present either in fetal liver or placenta. The risk of second malignancies caused by alkylating agents such as cyclophosphamide has been well documented in adults and children but to the best of our knowledge this is the first description of transplacental second cancer.

Maternal and fetal outcome after breast cancer in pregnancy

We compared 118 women with breast cancer (119 pregnancies) with 269 nonpregnant control subjects matched on important prognostic factors. The distribution of breast cancer stages among the 118 pregnant women was compared with that among 5115 cases of breast cancer in women of reproductive age. Fetal outcome was compared with that of a control group matched for maternal age. Women having breast cancer in pregnancy were 2.5 times more likely to have metastatic disease (95% confidence interval 1.1 to 5.3) and had a significantly lower chance of having stage I disease (p = 0.015). Survival of pregnant women did not differ from that of the controls. Birth weights of babies born to women with breast cancer were significantly lower than those of control babies after gestational age was adjusted for (3010 +/- 787 vs 3451 +/- 515 gm, p = 0.016). The two stillbirths in 85 pregnancies that continued to term (2.4%) was not statistically different from the 1.1% rate for Ontario. We analyzed all 223 births occurring in women who had any form of cancer in the same hospital during the same 30 years. There were 10 stillbirths among these 223 cases (4.4%), significantly more than expected in Ontario (p less than 0.0005; relative risk of 4.23 with 95% confidence interval 2.0 to 7.8). Our data suggest that pregnant women are at a higher risk of presenting with advanced disease because pregnancy impedes early cancer detection.

Fetal outcome after in utero exposure to cancer chemotherapy

BACKGROUND

Cancer is the second leading cause of death of women during the reproductive years, and its occurrence in pregnancy is between 0.07% and 0.1%.

METHODS

To analyze the effect of cancer on pregnancy, we compared 21 pregnancies occurring during 30 years in women who received chemotherapy for their cancer with a control group matched for maternal age and composed of women not exposed to known teratogens or reproductive risks during pregnancy.

RESULTS

Of 13 women exposed to chemotherapy during the first trimester, two of five whose pregnancies continued to term had major malformations in their infants, four had spontaneous abortions, and four had therapeutic abortions. Of four women with second-trimester exposure to chemotherapy, two had normal live births, one had a stillbirth, and one had a therapeutic abortion. All four pregnancies exposed to chemotherapy during the third trimester resulted in healthy live births. Infants exposed to chemotherapy had statistically significantly lower birth weights than their matched controls (2227 +/- 558 g vs 3519 +/- 272 g, P less than .001), due to both significantly lower gestational age and substantial intrauterine growth retardation (P less than .01). The trend for higher rate of stillbirth (1/11) agrees well with 10 stillbirths among all women with cancer in pregnancy without and with chemotherapy who gave birth (n = 223), when compared with the population of Ontario (P less than .0005).

CONCLUSIONS

This study confirms the increased likelihood of spontaneous abortions and major birth defects when chemotherapy is used during embryogenesis, whereas such a risk is not apparent beyond the first trimester. Because of the higher risk of stillbirth and intrauterine growth retardation, women with cancer should be monitored closely by a high-risk obstetric unit to define the optimal time of delivery.

Maternal and foetal outcome following Hodgkin's disease in pregnancy

The peak incidence of Hodgkin's disease occurs during the reproductive age, and its association with pregnancy is at a rate of between 1:1,000-1:6,000. We studied the effects of Hodgkin's Disease on the course and survival of 48 women who had Hodgkin's Disease and who were pregnant, and compared their outcome with non-pregnant matched women who were of similar stage of disease, age at diagnosis, and calenderic year of treatment. Twenty-year survival of pregnant women with Hodgkin's Disease was not different from that of their matched controls. Pregnant women with Hodgkin's Disease had similar distribution of stages to the controls.

Maternal and fetal outcome after invasive cervical cancer in pregnancy

Invasive carcinoma of the cervix is the most common gynecologic malignancy to occur during the reproductive years. To analyze the effects of pregnancy on the course and survival of invasive cervical cancer, we compared 40 women with invasive cervical cancer to 89 nonpregnant controls matched for age, calendric year of diagnosis, stage, and tumor type. Additionally, we compared the distribution of invasive cervical cancer stages among the 40 pregnant women with that among the 1,963 cases of invasive cervical cancer treated during the same 30 years in women less than 45 years of age registered in the same hospital. To evaluate pregnancy outcome, we compared babies born to women with invasive cervical cancer to babies born of women matched for maternal age and not exposed to known teratogens or reproductive risks during pregnancy. Thirty-year survival of pregnant women with invasive cervical cancer was identical to that of their matched controls. Women having invasive cervical cancer were 3.1 times more likely to be diagnosed with stage I disease (95% confidence interval, 1.6 to 6.2). Additionally, they had a significantly lower chance of being diagnosed with stages III and IV (P = .02). Babies born to women with invasive cervical cancer were similar in gestational age and rates of prematurity but had a lower birth weight than the matched controls. There were two stillbirths among the 24 pregnancies that continued to term (8%), not statistically different from the 1.1% rate for Ontario. Our data suggest that pregnancy per se does not adversely affect the survival of women with invasive cervical cancer. However, this study provides evidence that pregnant women are more likely to present with early disease because of regular, pregnancy-related obstetric exams. Moreover, there is an increased risk for stillbirth, which should lead to follow-up of these patients by a high-risk perinatal unit.