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Puma Biotechnology Stock Declines More Than 9% in a Month: Here's Why
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Key Takeaways
Puma Biotechnology shares fell 9.6% in a month on a weaker-than-expected 2026 revenue outlook.
PBYI expects 2026 total revenues of $214-$221M, with Nerlynx sales expected to be $194-$198M.
Initial phase II data on alisertib for lung cancer and breast cancer are expected in Q2 2026.
Shares of Puma Biotechnology (PBYI - Free Report) have tanked 9.6% in the past month, reflecting the growing investor concern regarding the company’s soft 2026 revenue outlook.
The company’s sole marketed product, Nerlynx (neratinib), is approved for treating early-stage HER2-positive breast cancer in patients previously treated with Roche’s (RHHBY - Free Report) Herceptin-based adjuvant therapy. Nerlynx is also approved in combination with Xeloda (capecitabine) for treating advanced or metastatic HER2-positive breast cancer patients who have received two or more prior anti-HER2-based regimens in the metastatic setting.
Nerlynx sales currently comprise the majority of PBYI’s top line. Sales of the drug increased 4.6% year over year to $204.1 million in 2025. Despite the increasing sales for Nerlynx, Puma Biotechnology issued a weaker-than-expected 2026 financial outlook last month.
This can be attributed to the primary reason for the stock’s decline in the past month.
PBYI’s 2026 Outlook Muted & Pipeline Updates
Puma Biotechnology’s top line currently comprises net product sales of Nerlynx and royalty revenues.
For full-year 2026, the company expects total revenues in the range of $214-$221 million, while net product revenues from Nerlynx sales are projected to be between $194 million and $198 million.
The guidance reflects a more cautious growth path for Nerlynx, suggesting a more conservative pace of near-term demand for the product.
Year to date, shares of Puma Biotechnology have gained 3.2% compared with the industry’s growth of 3.7%.
Image Source: Zacks Investment Research
PBYI is developing its pipeline candidate, alisertib, an aurora kinase A inhibitor, in separate mid-stage studies for treating hormone receptor-positive breast cancer as well as small-cell lung cancer.
The company is conducting ALISCA-Lung1, a phase II study (PUMA-ALI-4201) evaluating alisertib as a monotherapy for the treatment of patients with extensive-stage SCLC. Interim data from this study are expected in the second quarter of 2026.
Puma Biotechnology is also conducting a phase II ALISCA-Breast1 study on alisertib in combination with endocrine treatment for treating patients with chemotherapy-naïve HER2-negative, hormone receptor-positive metastatic breast cancer. Initial data from the study is also expected in the second quarter of 2026.
Per management, the successful development of the candidate is likely to enhance the company’s position in the anti-cancer drug market.
PBYI’s Sole Reliance on Nerlynx Amid Competition
Puma Biotechnology has no approved product in its portfolio other than Nerlynx. As a result, the company remains heavily dependent on Nerlynx for revenues and overall growth, which is a concern.
While the breast cancer market holds immense commercial potential, Nerlynx faces intense competition in the targeted space. Approved treatments include Roche's Herceptin and Novartis' Tykerb. A few other companies are also developing treatments targeting this disease.
The bearish 2026 outlook, coupled with stiff competition in the target market, remains a headwind for PBYI. Also, failure in ongoing studies on alisertib and pipeline/regulatory setbacks will hurt the stock further in future quarters.
Over the past 60 days, estimates for Phathom Pharmaceuticals’ 2026 earnings per share have increased from 23 cents to 28 cents, while the same for 2027 have increased from $2.22 to $2.25. PHAT’s shares have plunged 34.6% in the year-to-date period.
Phathom Pharmaceuticals’ earnings beat estimates in two of the trailing four quarters, while missing the same on the remaining two occasions, with the average surprise being 14.06%.
Over the past 60 days, estimates for ANI Pharmaceuticals’ 2026 earnings per share have increased from $8.28 to $8.99, while the same for 2027 have increased from $9.25 to $10.10. ANIP’s shares have fallen 5.9% in the year-to-date period.
ANI Pharmaceuticals’ earnings beat estimates in each of the trailing four quarters, with the average surprise being 22.21%.
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Puma Biotechnology Stock Declines More Than 9% in a Month: Here's Why
Key Takeaways
Shares of Puma Biotechnology (PBYI - Free Report) have tanked 9.6% in the past month, reflecting the growing investor concern regarding the company’s soft 2026 revenue outlook.
The company’s sole marketed product, Nerlynx (neratinib), is approved for treating early-stage HER2-positive breast cancer in patients previously treated with Roche’s (RHHBY - Free Report) Herceptin-based adjuvant therapy. Nerlynx is also approved in combination with Xeloda (capecitabine) for treating advanced or metastatic HER2-positive breast cancer patients who have received two or more prior anti-HER2-based regimens in the metastatic setting.
Nerlynx sales currently comprise the majority of PBYI’s top line. Sales of the drug increased 4.6% year over year to $204.1 million in 2025. Despite the increasing sales for Nerlynx, Puma Biotechnology issued a weaker-than-expected 2026 financial outlook last month.
This can be attributed to the primary reason for the stock’s decline in the past month.
PBYI’s 2026 Outlook Muted & Pipeline Updates
Puma Biotechnology’s top line currently comprises net product sales of Nerlynx and royalty revenues.
For full-year 2026, the company expects total revenues in the range of $214-$221 million, while net product revenues from Nerlynx sales are projected to be between $194 million and $198 million.
The guidance reflects a more cautious growth path for Nerlynx, suggesting a more conservative pace of near-term demand for the product.
Year to date, shares of Puma Biotechnology have gained 3.2% compared with the industry’s growth of 3.7%.
Image Source: Zacks Investment Research
PBYI is developing its pipeline candidate, alisertib, an aurora kinase A inhibitor, in separate mid-stage studies for treating hormone receptor-positive breast cancer as well as small-cell lung cancer.
The company is conducting ALISCA-Lung1, a phase II study (PUMA-ALI-4201) evaluating alisertib as a monotherapy for the treatment of patients with extensive-stage SCLC. Interim data from this study are expected in the second quarter of 2026.
Puma Biotechnology is also conducting a phase II ALISCA-Breast1 study on alisertib in combination with endocrine treatment for treating patients with chemotherapy-naïve HER2-negative, hormone receptor-positive metastatic breast cancer. Initial data from the study is also expected in the second quarter of 2026.
Per management, the successful development of the candidate is likely to enhance the company’s position in the anti-cancer drug market.
PBYI’s Sole Reliance on Nerlynx Amid Competition
Puma Biotechnology has no approved product in its portfolio other than Nerlynx. As a result, the company remains heavily dependent on Nerlynx for revenues and overall growth, which is a concern.
While the breast cancer market holds immense commercial potential, Nerlynx faces intense competition in the targeted space. Approved treatments include Roche's Herceptin and Novartis' Tykerb. A few other companies are also developing treatments targeting this disease.
The bearish 2026 outlook, coupled with stiff competition in the target market, remains a headwind for PBYI. Also, failure in ongoing studies on alisertib and pipeline/regulatory setbacks will hurt the stock further in future quarters.
Puma Biotechnology, Inc. Price
Puma Biotechnology, Inc. price | Puma Biotechnology, Inc. Quote
PBYI's Zacks Rank & Stocks to Consider
Puma Biotechnology currently carries a Zacks Rank #4 (Sell).
Some better-ranked stocks in the biotech sector are Phathom Pharmaceuticals (PHAT - Free Report) and ANI Pharmaceuticals (ANIP - Free Report) , each carrying a Zacks Rank #2 (Buy) at present. You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.
Over the past 60 days, estimates for Phathom Pharmaceuticals’ 2026 earnings per share have increased from 23 cents to 28 cents, while the same for 2027 have increased from $2.22 to $2.25. PHAT’s shares have plunged 34.6% in the year-to-date period.
Phathom Pharmaceuticals’ earnings beat estimates in two of the trailing four quarters, while missing the same on the remaining two occasions, with the average surprise being 14.06%.
Over the past 60 days, estimates for ANI Pharmaceuticals’ 2026 earnings per share have increased from $8.28 to $8.99, while the same for 2027 have increased from $9.25 to $10.10. ANIP’s shares have fallen 5.9% in the year-to-date period.
ANI Pharmaceuticals’ earnings beat estimates in each of the trailing four quarters, with the average surprise being 22.21%.